Preparation of citric acid-modified β-cyclodextrin/poly (acrylic acid-co- acrylamide) composite hydrogel for enhanced methylene blue adsorption

Preparation of citric acid-modified β-cyclodextrin/poly (acrylic acid-co- acrylamide) composite hydrogel for enhanced methylene blue adsorption | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Preparation of citric acid-modified β-cyclodextrin/poly (acrylic acid-co- acrylamide) composite hydrogel for enhanced methylene blue adsorption Ayiguzaili Abudiwayiti, Amatjan Sawut, Rena Simayi, Long Cheng This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8874053/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 7 You are reading this latest preprint version Abstract Water pollution poses a severe threat to human health and ecological systems, thereby demanding high-performance adsorbents for wastewater treatment. Herein, a novel composite hydrogel (CA-β-CD/P(AA-co-AM)) was synthesized via radical polymerization using citric acid-modified β-CD (CA-β-CD). Citric acid modification introduced functional sites, tuned cavity structure, and linked β-CD units into oligomer, overcoming native β-CD’s limitations to serve as an ideal hydrogel component. The incorporation of CA-β-CD into P(AA-co-AM) formed a porous network, enabled synergistic interactions, enhanced stability, and integrated CA-β-CD’s adsorption superiority with the polymer’s robust matrix. The structure and properties of the composite hydrogel were characterized by FT-IR, 1 H NMR, SEM, TGA, GPC, and XPS. It showed outstanding methylene blue (MB) adsorption via host–guest inclusion, hydrogen bonding, and electrostatic interactions, with a maximum capacity of 3743.23 mg/g. Adsorption followed pseudo-second-order kinetics and Langmuir isotherm, with rate controlled by intra-particle and liquid film diffusion. Importantly, the composite hydrogel maintained excellent reusability — after 10 consecutive adsorption–desorption cycles, the MB removal rate (R) remained above 92%. This work provides a promising strategy for cyclodextrin-derived adsorbents in dye wastewater treatment. β-cyclodextrin hydrogel Dye adsorption Methylene blue Wastewater treatment Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 1. Introduction Water scarcity and pollution have evolved into pressing global challenges, and synthetic dye contamination—primarily originating from textile, printing, and dyeing industries—poses particularly severe threats to aquatic ecosystems and human health [ 1 ]. Studies indicate that approximately 5–10% of these industrially produced dyes are discharged into aquatic systems through untreated or partially treated wastewater[ 2 ], exacerbating concerns about long-term environmental degradation and ecological imbalance. Common organic dyes in industrial effluents include methylene blue (MB), methyl orange (MO), methyl green (MG), basic fuchsine (BF), and Congo red (CR). Among this group, MB stands out as a typical cationic thiazine dye, finding extensive application across industrial manufacturing, chemical synthesis, and medical/surgical fields—such as textile coloring, reagent preparation, and tissue staining [ 3 , 4 ]. Despite its utility, MB exhibits high toxicity even at trace levels: concentrations as low as 0.1–10 mg/L can disrupt algal photosynthesis (a key link in aquatic food chains), induce DNA damage in aquatic organisms, and cause adverse effects in humans—including skin irritation, eye damage, and potential neurological disorders [ 5 ]. These risks underscore the urgency of developing efficient, eco-friendly technologies for MB removal from aqueous systems to safeguard environmental sustainability. Existing dye treatment technologies vary in efficacy and limitations. Chemical oxidation degrades MB but requires harsh conditions (e.g., strong acidity) and generates toxic byproducts [ 6 ], while membrane filtration suffers from frequent fouling and high operational costs that restrict large-scale use [ 7 ]. Biological degradation, though eco-friendly, is highly sensitive to temperature and pH fluctuations, often requiring 24–72 hours to achieve moderate removal rates [ 8 ]. Electrodialysis, while effective for dye separation, is hampered by high energy consumption and sensitivity to feedwater salinity—factors that increase operational costs and limit its applicability in low-salinity dye wastewater treatment [ 9 ]. Adsorption stands out among these methods for its simplicity, low energy consumption, and adaptability to diverse water matrices [ 10 ], yet traditional adsorbents like activated carbon (high cost), clay minerals (low capacity, < 100 mg/g), and biomass materials (poor structural stability) fail to meet the demands of high-efficiency dye treatment [ 11 , 12 ]. This gap has driven research toward advanced adsorbents with tailored structures and multifunctional properties. Hydrogels—three-dimensional cross-linked polymer networks capable of absorbing large volumes of water while retaining shape—have emerged as promising candidates for dye adsorption. [ 13 ] Their porous architecture ensures rapid dye molecule diffusion, and their surface chemistry can be adjusted to introduce active binding sites [ 14 ]. Natural polymer hydrogels (e.g., chitosan, alginate, cellulose) offer biocompatibility but suffer from weak mechanical strength and limited adsorption capacity [ 15 – 17 ]. Synthetic hydrogels like poly(acrylic acid-co-acrylamide) (P(AA-co-AM)) exhibit better stability but rely primarily on electrostatic attraction and hydrogen bonding for dye binding, resulting in low selectivity and capacity [ 18 ]. To address these shortcomings, researchers have integrated macrocyclic compounds into hydrogel matrices [ 19 ], with β-cyclodextrin (β-CD) drawing particular interest [ 20 ]. As a cyclic oligosaccharide composed of seven glucose units, β-CD features a hydrophobic internal cavity that forms stable inclusion complexes with MB via hydrophobic interactions, enhancing adsorption selectivity [ 21 ]. However, native β-CD has critical limitations: poor water solubility leads to agglomeration in hydrogels, a single adsorption mechanism (only host-guest inclusion) restricts capacity [ 22 ], and the absence of cross-linking sites makes it difficult to form stable bonds with polymer networks [ 23 ]. Traditional β-CD modifiers (e.g., epichlorohydrin, maleic anhydride) are toxic and require complex synthesis processes, creating a need for green, low-cost modification strategies [ 24 ]. To address these challenges, we first synthesized CA-β-CD oligomer using CA as a modifier; this CA-β-CD was subsequently incorporated into the P(AA-co-AM) network to form the CA-β-CD/P(AA-co-AM) composite hydrogel. We hypothesized that: (1) CA-based modification of β-CD would introduce additional carboxyl groups, optimize its cavity structure, promote β-CD oligomerization, and thereby overcome the inherent solubility and functional limitations of native β-CD; (2) integrating host–guest active CA-β-CD with a robust P(AA-co-AM) matrix would create a synergistic hydrogel system that significantly enhances both the adsorption capacity and selectivity toward methylene blue (MB). To verify these hypotheses, the structures and properties of CA-β-CD and the composite hydrogel were thoroughly characterized. The adsorption performance of the composite hydrogel was systematically evaluated and compared with that of unmodified P(AA-co-AM) hydrogels under same conditions. This study provides a green and efficient strategy for constructing high-performance β-cyclodextrin-based adsorbents and highlights the potential of natural polysaccharide composites in treating organic dye-contaminated wastewater. 2. Materials and methods 2.1 Experimental materials and apparatus Acrylic acid (AA, > 99%) was purchased procured Shandong Keyuan Bio-chemical Co., Ltd.; Acrylamide (AM, 99%) and 2-hydroxy-4'-(2-hydroxyethoxy)-2-methyl-propiophenone (PI) were purchased from Shanghai McLean Biochemical Technology Co., Ltd.; Citric acid (CA, 99%), N,N'-Methylenebisacrylamide (MBA, 99.5%), and anhydrous ethanol were acquired from Tianjin Zhiyuan Chemical Reagent Co., Ltd.; β-cyclodextrin (β-CD, ≥ 98%) was purchased from Shanghai Qingxi Chemical Technology Co., Ltd.; Methylene blue (MB, ≥ 98.5%), sodium hypophosphite (99%), and methyl orange (MO) were purchased from Tianjin Yongsheng Fine Chemical Co., Ltd.; Methyl green (MG) was purchased from Sinno Group Chemical Reagent Co., Ltd.; Congo Red (CR) was purchased from Tianjin Damiao Chemical Reagent Factory; Phenolphthalein was procured from Tianjin Shengmiao Fine Chemical Co., Ltd.; While sodium hydroxide (NaOH) was obtained from Tianjin Xinbote Chemical Co., Ltd.; The UV-Vis spectrophotometer was acquired from Shanghai Jinghua Technology Instrument Co., Ltd. 2.2 Preparation of CA-β-CD CA-β-CD was synthesized using the hydrothermal method, modified based on the reported procedure [ 25 ]. Dissolve 2.52 g of NaH 2 PO 4 and 23.05 g of CA in 20 mL of ultrapure water with stirring. Add 11.35 g of β-CD to the solution and stir until dissolved. The mixture should then be transferred to a reaction vessel and placed in a vacuum drying oven. Heat at 100°C for 1 hour, then increase the temperature to 120°C. leave to react for 6 hours. After the reaction, cool to room temperature. Slowly add the mixture dropwise to anhydrous ethanol to precipitate a white solid. Vacuum filtration, wash multiple times, and dry under vacuum at 60°C for 24 hours to obtain CA-β-CD. The preparation process is shown in Fig. 1 a: 2.3 Preparation of CA-β-CD/P(AA-co-AM) composite hydrogels First, weigh 2 g of CA-β-CD and dissolve it in 40 mL of distilled water with stirring. Dissolve 2.6 g of AM in 10 mL of distilled water. Once dissolved, slowly add this solution to the CA-β-CD solution while stirring to form a transparent Solution A. Neutralize 2.5 mL of AA solution using 5 M NaOH solution. Prepare AA solutions with different neutralization degrees, mix them thoroughly, and cool to room temperature. Subsequently, sequentially add 0.12 g of MBA and 0.08 g of PI mixed solution. After ultrasonic treatment for 10 min, obtain a uniform solution B. Calculate the neutralization degree according to Eq. 1 [ 26 ]. In the equation, a represents the neutralization degree of AA (%); b denotes the volume of NaOH (L); m AA indicates the weight of AA (g). Measure 5, 10, 15, 20 and 25 mL of Solution A separately, mix each with Solution B, and sonicate for 5 minutes. Transfer the mixture to a specific mold (quartz glass plate, 10×10×2 cm), irradiate under UV light for 5 min to initiate polymerization, forming a gel. Wash the gel, dry at 70°C for 24 hours, grind, and sieve through a 40–60 mesh screen. Store in sealed sample bags for future use. The composite hydrogel synthesis is schematically illustrated in Fig. 1 b: 2.4 Determination of β-CD and carboxyl content in CA-β-CD The number of active carboxyl groups in CA-β-CD was determined by titration using 0.01 M HCl solution [ 27 ]. Active β-CD was quantified via phenolphthalein titration [ 28 ]. see the supporting information for details. 2.5 Characterization of CA-β-CD and CA-β-CD/P(AA-co-AM) Fourier transform infrared (FT-IR) spectra of the samples were obtained using a VERTEX 70 RAMI (Bruker). X-ray photoelectron spectroscopy (XPS) data were acquired using an ESCALAB 250 Xi (Thermo Fisher Scientific). The microstructure of the samples was examined using a scanning electron microscopy (SEM, JSM-7001F, Japan). Thermal stability was evaluated using thermogravimetric-differential thermal analysis (TGA) (Hitachi STA7300, Japan). The hydrogen nuclear magnetic resonance ( 1 H NMR) spectra of β-CD and CA-β-CD were acquired on a Bruker AVANCE NEO 600. 2.6 Swelling performance testing Weigh 0.1 g of the composite hydrogel and place it in 100 mL of distilled water for swelling performance testing. At predetermined time intervals, remove the swollen composite hydrogel, blot residual surface moisture with filter paper, and weigh it. Calculate the swelling degree (SD) according to Eq. 2 : $$\:\text{SD=}\frac{\left({\text{w}}_{\text{t}}\text{-}{\text{w}}_{\text{0}}\right)}{{\text{w}}_{\text{0}}}$$ 2 In the equation, W t denotes the mass of the swollen hydrogel at time t (g); W 0 denotes the initial mass of the composite hydrogel (g). 2.7 Adsorption performance testing This study investigates the adsorption performance of composite hydrogels toward MB. Precisely weigh 10 mg of composite hydrogel and add it to 25 mL of MB solution. Shake the mixture at 130 rpm in a shaker at room temperature for 240 minutes to achieve adsorption equilibrium. To ensure adsorption saturation, the supernatant was removed and diluted to 25 mL. The MB concentration was measured using a UV-visible spectrophotometer. Additionally, the effects of adsorbent dosage, initial dye concentration, pH, temperature, and various ions on adsorption performance were investigated. All experiments were conducted in triplicate, and the results represent the average values. The adsorption capacity Q e , total adsorption Q t , and removal efficiency R (%) of the composite hydrogel were calculated according to Eqs. 3 , 4 , and 5 , respectively [ 26 ]. $$\:{\text{Q}}_{\text{e}}\text{=}\frac{\left({\text{C}}_{\text{0}}\text{-Ce}\right)\text{×V}}{\text{m}}$$ 3 $$\:{\text{Q}}_{\text{t}}\text{=}\frac{\left({\text{C}}_{\text{0}}\text{-}{\text{C}}_{\text{e}}\right)\text{×V}}{\text{m}}$$ 4 $$\:\text{R=}\frac{{\text{C}}_{\text{0}}\text{-}{C}_{e}}{{\text{C}}_{\text{0}}}\text{×100%}$$ 5 In the equation, Q e and Q t represent adsorption capacity (mg/g); R denotes removal efficiency (%); The initial concentration of MB is denoted by C 0 (mg/L), whilst C e and C t represent the MB concentrations at adsorption equilibrium (mg/L); The volume of MB used is denoted by V (L), and m is the mass of the composite hydrogel (g). 2.7.1 MB standard curve A series of MB solutions with concentrations ranging from 3 to 8 mg/L were prepared. Absorbance was measured at the maximum absorption wavelength of 664 nm, and a standard curve for MB was plotted (Fig. S4a). The experimental results demonstrated a good linear relationship between absorbance and MB concentration, with the linear regression equation being y = 8.9721x − 0.2577 (R 2 = 0.9997). 2.7.2 Selective adsorption of different dyes In practical wastewater treatment, dyes typically exist as mixtures. To accurately investigate the selectivity of composite hydrogels, this study designed adsorption experiments using a binary anionic/cationic dye system. Representative cationic dyes MB and MG, along with anionic dyes CR and MO, were first selected for adsorption testing. Subsequently, mixed dye solutions (CR/MB, MO/MB, CR/MG, MO/MG) were prepared for adsorption testing. 2.8 Adsorption kinetics and isotherm studies In adsorption kinetics experiments, composite hydrogels were added to MB solutions. After varying durations, adsorption was halted, MB concentrations were measured, and kinetic curves were plotted. Composite hydrogels were added to MB solutions of different concentrations for 12 hours of adsorption to ensure adsorption saturation before plotting adsorption isotherms. 2.9 Cycle performance testing The potential cyclic performance of the composite hydrogel was evaluated through 10 adsorption-desorption cycles. In each cycle, the composite hydrogel was first placed in a methylene blue solution for adsorption saturation, then filtered out and desorbed in a mixed oxalic acid-anhydrous ethanol eluent. Residual eluent was rinsed off with distilled water before conducting the cyclic test. 3. Results and discussion 3.1 Mechanism of composite hydrogel preparation Under acidic conditions at a high temperature, the carboxyl group in CA undergoes protonation to form a highly electrophilic intermediate (CA-COOH + H⁺ ⇌ CA-C⁺(OH) 2 ). the oxygen atom on β-CD-OH acts as a nucleophile, attacking the carbonyl carbon of the protonated carboxyl group. This reaction results in the elimination of one water molecule and the formation of an ester bond (β-CD-OH + CA-C⁺(OH) 2 → β-CD-O-C(= O)-CA + H 2 O + H⁺) [ 29 ], yielding the cross-linked polymer CA-β-CD (Fig. 2 a). Under UV irradiation, the C-C bond between the aliphatic carbon and the carbonyl group in the photo-initiator (PI) breaks to generate P· and I· radicals [ 30 ], which reacts with the C = C bonds in the AA/AM monomers to initiate chain growth and generate polymer radicals (C-C-C-C · , C-C-C-C-C-C-C · …). These radicals then react with MBA to form a three-dimensionally crosslinked P(AA-co-AM) polymer [ 31 ]. This network combines with CA-β-CD polymers to form CA-β-CD/P(AA-co-AM) composite hydrogels (Fig. 2 b). 3.2 Structural characterization and analysis The FTIR spectra of β-CD, CA, CA-β-CD, and CA-β-CD/P(AA-co-AM) are shown in Fig. 3 (A).The β-CD exhibits a -OH stretching vibration peak at 3385 cm − 1 and an asymmetric methylene (CH 2 ) stretching vibration peak at 2932 cm − 1 [ 27 ] − [ 32 ]. Absorption peaks at 1654 and 1407 cm − 1 correspond to -OH bending vibrations, while peaks at 941, 1029, and 1157 cm − 1 represent α-1,4-glycosidic backbone vibrations, C = O, and C-OH stretching vibrations of β-CD [ 33 ],[ 34 ]. CA-β-CD exhibits an -OH stretching vibration peak at 3425 cm − 1 and the ester group (carboxyl) stretching peak at 1743 cm − 1 , indicating esterification between β-CD's -OH and CA's carboxyl group [ 11 , 12 ]. Meanwhile, characteristic vibration peaks at 2932, 1163, and 1029 cm − 1 corresponding to C-H, C-O-C, and C-O bonds of the β-CD sugar ring structure remain intact, indicating that the β-CD backbone retains its integrity during crosslinking [ 25 ] , [ 34 ]. This provides preliminary evidence for the successful modification of β-CD. CA-β-CD/P(AA-co-AM) exhibits -OH and N-H stretching vibration peaks at 3547 cm − 1 , while the peaks at 1682 and 1562 cm − 1 correspond to C = O stretching in AA and amide group (C-N) stretching in AM [ 35 ]. These results confirm the successful preparation of CA-β-CD/P(AA-co-AM). The 1 H NMR spectra of β-CD and CA-β-CD are presented in Fig. 3 B. In the case of β-CD (Fig. 3 B a), the signals for Ha and Hb appear at δ 5.68 ppm, the peak for Hc appears at 4.41 ppm, the characteristic peak for H 1 appears at δ 4.84 ppm, and the characteristic peaks for H 2 –H 6 appear in the range of δ 3.32–δ 3.64 ppm [ 36 ]. All chemical shifts are referenced to the D 2 O solvent peak (δ 4.79 ppm). In CA-β-CD (Fig. 3 B b), the H 1 signal from the β-CD pyranose glucose unit appears at δ 5.06 ppm, while signals for H 2 –H 6 appear in the range δ 3.63–3.98 ppm. The ester protons (B) appeared at δ 4.63–4.66 ppm [ 37 ]. The methylene protons (A) in the CA crosslinker peaked at δ 2.82–2.98 ppm, while two single peaks at δ 6.60 and δ 7.47 ppm (labeled C and D, respectively) corresponded to cis- and trans-aconitic acid ester structures [ 38 ]. This result is consistent with the characteristics of the FTIR spectrum, which confirms the successful modification. To ascertain the thermal stability of the composite hydrogel, thermogravimetric analysis (TGA) was performed on β-CD, CA-β-CD, and CA-β-CD/P(AA-co-AM) (see Fig. 3 C). The thermal decomposition of β-CD occurred at temperatures below 100°C, resulting in a weight loss of around 12%, This was primarily due to water evaporation from the surface or cavities of the β-CD. Between 100–360°C, significant weight loss of approximately 65.17% occurred, corresponding to the thermal decomposition of β-CD's macrocyclic structure [ 39 ]. At 360–500°C, the final residue rate reached 13.28%. CA-β-CD exhibited approximately 13.49% weight loss below 200°C, attributed to water evaporation from the polymer surface [ 40 ]. Between 250–360°C, weight loss reached about 48%, indicating decomposition of the polymer backbone structure. After 500°C, the residual rate was approximately 28.52%, demonstrating that crosslinking effectively enhanced thermal stability. CA-β-CD/P(AA-co-AM) exhibits a 10% weight loss below 200°C, attributed to water evaporation from the composite hydrogel. Between 200–436°C, the weight loss reaches approximately 16.64%, resulting from the decomposition of organic acids, β-CD macrocycles [ 41 ], decomposition of carboxyl and amide groups [ 35 ], and main-chain breakage [ 42 ], resulting in a final residue rate of 52.85%. CA-β-CD/P(AA-co-AM) exhibits excellent thermal stability. To investigate the effect of chemical modification on the microstructure of the material, morphological analysis of β-CD and CA-β-CD was performed using SEM (Fig. S3). In comparison to the conventional plate-like structure of β-CD, CA-β-CD exhibited an agglomerate structure with a rough surface and a multitude of pores, further confirming the successful modification of β-CD. Figure 4 illustrates the SEM, MAPPING and EDS results of the composite hydrogel before and after MB adsorption. Pre-adsorption (Fig. 4 A a-c) samples exhibited a porous structure with interconnected macropores and surface micropores/wrinkles. The high porosity and rough surface provided abundant adsorption sites for MB. Post-adsorption (Fig. 4 B d-f), the morphology underwent significant changes: pores were filled, channels became denser, and pore sizes decreased, indicating successful adsorption of MB into the gel pores and onto its surface. This phenomenon is attributed to the competitive adsorption of MB and water molecules on the gel surface, which weakens the repulsive forces between polymer chains through electrostatic interactions, leading to pore size contraction during swelling. Further analysis via MAPPING and EDS before and after adsorption (Fig. 4 C-D) reveals a significant increase in S content with uniform distribution post-adsorption, confirming that MB has uniformly coated the hydrogel surface. The total acid group (TA) content in CA-β-CD was determined to be 4 mmol/g by titration reflecting the combined amount of carboxyl and ester groups. the β-CD cavity content (TC) was determined to be 0.366 mmol/g, phenolphthalein titration, with a degree of substitution (DS) of 1.56. Based on the β-CD calibration curve (Fig. S1 , y = 0.64576–0.03339x, R 2 = 0.9984), it was found that phenolphthalein was able to embed into the hydrophobic cavity of β-CD under alkaline conditions, resulting in decreased absorbance. This indicates that CA-β-CD successfully retained the cavity structure of β-CD [ 27 ]. Therefore, the abundant total acidic groups in CA-β-CD and the β-CD cavity structure synergistically provide numerous adsorption sites for various dye molecules [ 33 ]. The gel permeation chromatography (GPC) results shown in Fig. S2 indicate that the CA-β-CD weight-average molecular weight (Mw) is 8.935 kDa and the polydispersity index (PDI) is 1.79. This polymer formation aligns with the step-growth polymerization mechanism and demonstrates characteristics of a soluble macromolecular crosslinking agent. These results are consistent with FTIR and titration data, collectively confirming the successful synthesis of the CA-β-CD polymer. 3.3 Adsorption experiment of CA-β-CD/P(AA-co-AM) 3.3.1 Single-factor experiment The study examines how reaction parameters affect the adsorption performance of CA-β-CD/P(AA-co-AM). These parameters include the molar ratio of CA and β-CD, reaction time, AA neutralization degree, MBA dosage and CA-β-CD loading amount. The results are shown in Fig. S4. The optimal preparation conditions, as determined by single-factor optimization, were as follows: CA: β-CD molar ratio of 1:12, reaction time of 6 hours, neutralization degree of 85%, MBA dosage of 0.12 g, and CA-β-CD loading of 0.2 g. The hydrogel obtained under these combined conditions exhibited the best adsorption performance. Detailed analysis in the supporting information. 3.4 Performance testing of CA-β-CD/P(AA-co-AM) 3.4.1 Swelling performance testing Figure 5 A indicates that CA-β-CD/P(AA-co-AM) exhibits the highest adsorption capacity for MB, with a Qe value of 2353.08 mg/g, surpassing both the P(AA-co-AM) hydrogel (2080.75 mg/g) and β-CD (13.34 mg/g). In swelling performance tests (Fig. 5 B), CA-β-CD/P(AA-co-AM) rapidly swelled in both media. Its adsorption capacity (Q eq ) in distilled water was 198.05 g/g, primarily due to ionization of hydrophilic groups releasing Na⁺ and -COO⁻ ions. This fully expanded the three-dimensional network structure. The osmotic pressure difference between the interior and exterior of the gel facilitated rapid water absorption. By contrast, in a 0.9% NaCl solution, Q eq was 52.08 g/g. Within the NaCl solution, Na⁺ ions shielded the electrostatic repulsion between -COO⁻ groups, limiting the expansion of the hydrogel network. This reduced osmotic pressure difference consequently restricted swelling capacity. 3.4.2 Effect of adsorption time on MB adsorption performance The composite hydrogel demonstrated an increase in adsorption capacity for MB over time, as illustrated in Fig. 5 C. with increase in adsorption time, the Q e exhibited a gradual rise, reaching adsorption equilibrium at 4 h with a Q e of 2353.08 mg/g. The extension of the adsorption time to 12 h resulted in a marginal increase in Q e , further confirming the attainment of adsorption equilibrium. 3.4.3 Effect of initial MB concentration The present study investigates the potential application of CA-β-CD/P(AA-co-AM) in wastewater containing different concentrations of dye. Figure 5 D shows how the initial MB concentration (100–3000 mg/L) affects its adsorption performance. As the MB concentration increased from 100 mg/L to 3000 mg/L, the Q e of the composite hydrogel rose from 243.56 mg/g to 5061.21 mg/g. The collision frequency between the dye and the adsorbent surface increased with rising concentration, thereby promoting the adsorption process. However, When the MB concentration was increased further, the growth of Q e gradually slowed down. This was attributed to the fixed dosage of the adsorbent and the limited number of active adsorption sites on its surface, which were approaching saturation [ 43 ]. 3.4.4 Effect of different ion strengths on MB adsorption performance Multiple ions present in actual wastewater affect the adsorption performance. The influence of metal cations at different valence states (Na + , Ca 2+ , Fe 3+ ) on the adsorption performance of CA-β-CD/P(AA-co-AM) was investigated (Fig. 5 E). As ion concentration increased, the Q e of MB gradually decreased, with Na⁺ exhibiting the least impact and Fe 3+ having the greatest effect. Reasons for Q e decrease: Metal ions compete with MB for adsorption sites while forming complexes with -COO⁻ groups in the composite hydrogel network [ 44 ], increasing crosslink density and weakening electrostatic repulsion between molecular chains. This restricts the expansion of the three-dimensional network. Furthermore, the addition of ions reduces osmotic pressure within the hydrogel, hindering MB adsorption. Higher ion valence intensifies competition, leading to decreased MB adsorption capacity with increasing metal ion valence [ 45 ]. 3.4.5 Effect of composite hydrogel dosage on MB adsorption performance The amount of adsorbent is a key parameter affecting the adsorption performance of composite hydrogels (Fig. 5 F). Increasing the adsorbent dosage from 5 to 25 mg caused a decrease in the Q e from 3040.47 to 979.52 mg/g and an increase in R value from 60.81% to 97.95%. As the dosage of adsorbent increases, so dose the number of active sites utilized in the system, but these remains unsaturated. This leads to reduced utilization efficiency and consequently lower adsorption capacity [ 46 , 47 ]. At an adsorbent dosage of 10 mg, Q e reached 2353.08 mg/g and R achieved 93.40%. Taking into account both adsorption performance and cost-effectiveness, subsequent experiments selected 10 mg as the optimal dosage for the composite hydrogel. 3.4.6 Effect of different pH levels on MB adsorption performance To investigate the effect of pH on the performance of MB adsorption, 10 mg of composite hydrogel was added to the MB solution and the Q e and R values were measured at different pH levels, The results are shown in Fig. 5 G. The Qe of MB adsorption by the composite hydrogel increased with rising pH. Under acidic conditions (pH < 5), both the adsorption capacity and efficiency were low. This was primarily due to abundant H⁺ ions in the solution competing for adsorption sites with MB, while the carboxyl groups in the composite hydrogel underwent protonation, converting to -COOH. This conversion weakened the electrostatic adsorption interaction with MB molecules [ 11 , 12 ]. As pH increases, adsorption performance improves. Decreased H⁺ concentration enhances the negative charge density on the adsorbent surface, converting -COOH groups in the composite hydrogel to -COO⁻ [ 48 ], thereby strengthening electrostatic adsorption capacity toward MB [ 49 ]. 3.4.7 Effect of temperature on MB adsorption performance Temperature is one of the key factors that influence adsorption performance. To investigate the adsorption efficiency of composite hydrogels toward MB at different temperatures, a systematic study was conducted within the range of 25 to 75°C (Fig. 5 H). As the temperature increased from 25 to 75°C, the Q e of MB adsorption by the composite hydrogel decreased from 2353.08 to 1932.92 mg/g, and the R decreased from 93.40% to 77.31%. This suggests that elevated temperatures are detrimental to effective MB adsorption. The adsorption process is a thermally active reaction [ 50 ]. Increased temperature may induce contraction of the composite hydrogel network structure, thereby reducing the probability of contact between MB molecules. Concurrently, it impedes the adsorption reaction, resulting in reductions in Q e and R. 3.4.8 Adsorption thermodynamics During the adsorption process, changes in thermodynamic parameters are crucial factors for studying the adsorption performance of composite hydrogels. Thermodynamic parameters such as Gibbs free energy change (ΔG), enthalpy change (ΔH), and entropy change (ΔS) were calculated using Eqs. 6 , 7 , and 8 , systematically analyzing the energy variation patterns of composite hydrogels during adsorption. $$\:\text{Ln}\left(\frac{\text{Qe}}{{\text{C}}_{\text{e}}}\right)\text{=}\frac{\text{ΔS}}{\text{R}}\text{-}\frac{\text{ΔH}}{\text{RT}}$$ 6 $$\:\text{ΔG=ΔH-TΔS}$$ 7 $$\:\text{Δ}\text{G=-RT}\text{ln}\left(\frac{\text{Qe}}{\text{Ce}}\right)$$ 8 In the equation, R is the ideal gas constant (8.314 J/mol K); T is the temperature in kelvins (K); C e is the equilibrium concentration of MB (mg/L). By plotting the curve of ln (Q e /C e ) versus 1/T (Fig. 5 I), a good linear relationship is observed. The thermodynamic parameters of the adsorption process are listed in Table S1 . All ΔG values are negative (-8.8365 to -6.2017 kJ/mol), indicating that the adsorption process is spontaneous [ 51 ]. The negative ΔH value of (-23.9866 kJ/mol) indicates that the adsorption of MB by the composite hydrogel is an exothermic process, reflecting its favorable thermodynamic adsorption properties. Furthermore, the negative ΔS value (-51.7721 J/mol K) reflects a reduction in degrees of freedom at the solid/liquid interface during adsorption, indicating enhanced molecular order [ 52 ]. 3.5 Experiments on the selectivity of CA-β-CD/P(AA-co-AM) toward different dyes 3.5.1 Testing the cycling performance of composite hydrogels To investigate the reusability of the composite hydrogel, 10 consecutive adsorption-desorption cycles were conducted (Fig. 6 A). As the number of cycles increased, the R value decreased from 98.20% to 92.33%, yet the hydrogel retained a certain adsorption capacity, demonstrating promising potential for cyclic application in contaminated water systems. The decline in R primarily resulted from strong electrostatic or hydrogen bonding interactions forming between some MB molecules and the hydrogel, firmly occupying active sites and making complete desorption difficult during the desorption process. This led to a gradual reduction in effective adsorption sites [ 45 ]. The comparative Q e values of the composite hydrogel for four dyes are shown in Fig. 6 D, revealing distinct adsorption capacities for different dyes. MB exhibited the highest Qe (2353.08 mg/g), followed by MG (1442.22 mg/g) and MO (731.06 mg/g), while CR showed the lowest Qe of only 166.81 mg/g. To further investigate adsorption selectivity, experiments were conducted with mixed dye systems (Fig. 6 B, C, E, F). In the MO/MB mixture, MB exhibits characteristic absorption peaks at 664 nm and 612 nm, corresponding to its monomer and dimer forms, respectively. These dimers self-assemble via face-to-face interactions mediated by π–π stacking and hydrogen bonding [ 53 ]. As the adsorption time extended from 1 h to 6 h, the intensity of the MB absorption peak decreased, while the peak intensity of MO at 465 nm showed minimal change. The peak intensity of CR at 500 nm remained essentially constant over time, whereas the characteristic absorption peak intensity of MG at 633 nm exhibited a marked decrease over time. The composite hydrogel exhibits high selective adsorption toward cationic dyes. This selectivity arises from the effective interactions between the cationic dyes and functional groups within the composite hydrogel. These include the abundant carboxyl groups in AA and CA-β-CD, the amino groups on the AM segments, and the hydroxyl groups in the cyclodextrin. These interactions occur via electrostatic forces, hydrogen bonding, and host-guest interactions, thereby enabling selective adsorption of the cationic dyes. 3.6 Adsorption isotherms of CA-β-CD/P(AA-co-AM) To thoroughly investigate the adsorption process of composite hydrogels, experimental data were systematically analyzed using three adsorption isotherm models: Langmuir, Freundlich, and Temkin. The Langmuir adsorption isotherm is expressed as Eq. 9 [ 54 ]: $$\:{\text{Q}}_{\text{e}}\text{=}\frac{{\text{K}}_{\text{L\:}}{\text{Q}}_{\text{m}}\text{}{\text{C}}_{\text{e}}}{\text{1+}{\text{K}}_{\text{L\:}}\text{}{\text{C}}_{\text{e}}}$$ 9 In the equation, Q e representative of the equilibrium adsorption capacity (mg/g); C e denotes the dye concentration at adsorption equilibrium (mg/L); Qₘ indicates the maximum adsorption capacity (mg/g) and K L is the Langmuir adsorption constant (L/mg). Based on the linear fitting results presented in Fig. 7 A and Table S2, the composite hydrogel exhibits a Q m of 3743.23 mg/g for MB and a K L value of 0.02381 L/mg. The separation factor (R L ) is a dimensionless parameter used to assess the ease of adsorption processes on Langmuir isotherms, defined by Eq. 10 : $$\:{\text{R}}_{\text{L}}\text{=}\frac{\text{1}}{\text{1+}{\text{C}}_{\text{0}}{\text{k}}_{\text{L}}}$$ 10 The value of R L is closely related to the adsorption process. When R L > 1, adsorption is unfavorable. When R L = 1, adsorption is linear. When 0 < R L < 1, adsorption is easily initiated and a higher R L value within this range promotes the reaction; R L = 0 signifies an irreversible adsorption reaction. The calculated R L values in this study range from 0.01381 to 0.2958, falling within the (0 < R L < 1) interval. This indicates that the adsorption process proceeds in a favorable direction. The Freundlich adsorption isotherm is expressed as Eq. 11 [ 54 ]: $$\:\text{Ln}{\text{Q}}_{\text{e}}\text{=}\frac{\text{1}}{\text{n}}\text{ln}{\text{C}}_{\text{e}}\text{+}\text{ln}{\text{k}}_{\text{f}}$$ 11 In the equation, K f represents the Freundlich adsorption constant (L/mg); 1/n characterizes the heterogeneity factor of the adsorbent surface. A higher K f value indicates superior adsorption performance of the composite hydrogel, while a value closer to 0 reflects stronger surface heterogeneity. Conversely, a value closer to 1 suggests the adsorption process is chemisorption. Based on the fitting results in Fig. 7 B and Table S2, this study calculated 1/n = 0.45799, indicating a heterogeneous adsorption process, with K f = 217.78 L/mg. The Temkin adsorption isotherm is expressed as Eq. 12 [ 54 ]: $$\:{\text{Q}}_{\text{e}}\text{=}\frac{\text{RT}}{{\text{b}}_{\text{T}}}\text{ln}{\text{C}}_{\text{e}}\text{+}\frac{\text{RT}}{{\text{b}}_{\text{T}}}\text{ln}{\text{A}}_{\text{T}}$$ 12 In the equation, R is the ideal gas constant 8.314 J/ (mol K); T is the reaction temperature (K); b T is the Temkin constant (J/mol); A T is the Temkin isothermal constant (L/g). Based on the linear fitting results from Fig. 7 C and Table S2, b T = 3.511 J/mol and A T = 0.352 L/g were calculated. Of the Langmuir, Freundlich, and Temkin adsorption isotherm models, the Langmuir model (R 2 = 0.9989) provided the best fit, significantly outperforming the Freundlich model (R 2 = 0.9105) and the Temkin model (R 2 = 0.8864). This suggests that the adsorption process is more closely aligned with the Langmuir model, which represents single-layer chemisorption with uniformly distributed adsorption sites [ 55 ]. 3.7 Adsorption Kinetics of CA-β-CD/P(AA-co-AM) Adsorption kinetic parameters are considered to be pivotal in the evaluation of the adsorption performance of composite hydrogels. The adsorption process is analyzed using the following kinetic models: the pseudo-first-order (PFO), pseudo-second-order (PSO), and intra-particle diffusion models. The PFO kinetic model is expressed as Eq. 13 : $$\:\text{Ln}\left({\text{Q}}_{\text{e}}\text{-}{\text{Q}}_{\text{t}}\right)\text{=}\text{ln}{\text{Q}}_{\text{e}}\text{-}{\text{K}}_{\text{1}}\text{t}$$ 13 The PSO kinetic model is shown in Eq. 14 : $$\:\frac{\text{T}}{\text{Qt}}\text{=}\frac{\text{t}}{{\text{Q}}_{\text{e}}}\text{+}\frac{\text{1}}{{\text{K}}_{\text{2}}{\text{Q}}_{\text{e}}^{\text{2}}}$$ 14 The intra-particle diffusion model is shown in Eq. 15 : $$\:{\text{Q}}_{\text{t}}\text{=}{\text{k}}_{\text{i}}{\text{t}}^{\raisebox{1ex}{$\text{1}$}\!\left/\:\!\raisebox{-1ex}{$\text{2}$}\right.}\text{+}{\text{C}}_{\text{I}}$$ 15 In the equation, Q t represents the adsorption amount at time t (mg/g); t denotes the adsorption time (min); k 1 is the pseudo-first-order adsorption rate constant (min − 1 ); k 2 is the pseudo-second-order adsorption rate constant g/ (mg min); k i is the intraparticle diffusion rate constant mg/ (g min 0.5 ); C is the intraparticle diffusion model constant. Figure 7 (E-F) displays the fitting curves for the PFO and PSO kinetic models, with corresponding data detailed in Table S3. The correlation coefficient (R 2 ) for the PFO kinetic model is significantly lower than that for the PSO model, with the latter's R 2 approaching 1. The Q e values calculated from the PFO kinetic model differ significantly from the experimentally obtained Q exp values, indicating that the adsorption process better conforms to the PSO kinetic model. The adsorption mechanism is classified as chemical adsorption [ 56 ]. The fitting results and corresponding parameters for the intra-particle diffusion model are detailed in (Fig. 7 D, Table S4). All fitted lines did not pass through the origin and exhibited non-zero intercepts, indicating that a single independent mechanism does not dominate the MB adsorption process but rather results from the combined effects of surface adsorption and intra-particle diffusion [ 57 ]. The distinct intercepts observed on the vertical axis of the fitted curves further confirm that liquid film diffusion resistance significantly influences the adsorption rate [ 56 ]. 3.8 Adsorption mechanism of CA-β-CD/P(AA-co-AM) To investigate the adsorption mechanism of CA-β-CD/P(AA-co-AM) toward MB, FTIR and XPS characterization was performed on samples before and after adsorption. As shown in FTIR Fig. 8 B, characteristic MB peaks appeared at 1600, 1394, 1489, 1139, 884, and 661 cm − 1 , corresponding to the skeletal vibration of aromatic rings, the stretching vibration of -CH 3 , the bending vibration of -C = N, C-N, and aromatic C-H out-of-plane, and the vibration of C-S-C bonds [ 58 , 59 ], indicating successful MB adsorption onto the hydrogel surface [ 60 ]. Multiple characteristic peaks shifted, with the -OH and N-H stretching vibration peak moving from 3475 to 3448 cm − 1 , suggesting hydrogen bond formation between MB and the hydrogel [ 61 ]. The C = O stretching vibration peak shifted from 1685 to 1768 cm − 1 , with altered peak shape and intensity, indicating changes in the chemical environment around the carbonyl group. The C–H stretching vibration peak shifted from 2947 to 2922 cm − 1 , potentially forming C–H⋯O = C or C–H⋯N hydrogen bonds [ 62 ]. Additionally, electrostatic interactions exist between -COO- and -N(CH 3 ) 2 in MB [ 63 ]. The full XPS spectrum (Fig. 8 C) reveals the presence of C, O, Na, S, and N elements in the composite hydrogel. Following adsorption, the intensity of the Na 1s peak decreased while that of the S 2p peak increased, indicating ion exchange [ 62 ]. In the C 1s spectrum (Fig. 8 D,G), pre-adsorption peaks at 283.52, 284.80, 286.70, and 287.80 eV correspond to C-C, C = C/C-C/C-H, C = O/C-O-C, and C = O functional groups [ 7 ]. After adsorption, binding energy shifts occur, with C-O and C-S peaks appearing at 286.19 and 287.13 eV. In the N 1s spectrum (Fig. 8 E,H), pre-adsorption peaks at 398.43, 401.40, and 402.34 eV correspond to -NH 3 + , -C = N⁻, C-N, -NH 2 + , -NH⁻, and -C = N⁻ in PAM [ 64 ]. After adsorption, peaks appear at 398.71 and 401.33 eV, corresponding to -N(CH 3 ) 2 and O = C-N in MB [ 65 ]. The shift in binding energy further indicates hydrogen bonding interactions. The four peaks at 530.08, 531.2, 532.63, and 534.70 eV in the O 1s spectrum (Fig. 8 F,I) correspond sequentially to the O-C = O, -C = O, C-O, and -C = O bonds in CA-β-CD and PAA [ 66 , 67 ]. After adsorption, the binding energy shifts but no new peaks appear. The adsorption mechanism of the composite hydrogel (Fig. 8 A), The adsorption mechanism primarily involves: (1) electrostatic interactions between MB and -COO⁻ groups in PAA and CA-β-CD; (2) host-guest inclusion complex formation as MB enters the β-CD cavity; (3) hydrogen bonding between MB and numerous hydroxyl groups in PAA, PAM, and CA-β-CD. These synergistic interactions collectively enhance the adsorption performance of the composite hydrogel. To evaluate the adsorption performance of the composite hydrogel toward MB, it was compared with previously reported adsorbents in the literature. The results indicate that CA-β-CD/P(AA-co-AM) exhibits superior MB adsorption capacity compared to most adsorbents listed in Table S5. 4. Conclusion This study successfully prepared a CA-β-CD/P(AA-co-AM) composite hydrogel with a porous network structure and abundant active groups by crosslinking CA with β-CD and copolymerizing it with AA and AM. The chemical structure, composition, and stability of the composite hydrogel were characterized using FTIR, 1 H NMR, TGA, XPS, and SEM, confirming the successful preparation of both CA-β-CD and CA-β-CD/P(AA-co-AM). To investigate the adsorption performance of CA-β-CD/P(AA-co-AM) towards MB, the study revealed that the adsorption process is influenced by solution pH, adsorbent dosage, initial MB concentration, adsorption time, and varying salt ion concentrations. Adsorption isotherm results demonstrated that the composite hydrogel exhibits excellent adsorption capacity for MB, with a maximum adsorption capacity reaching 3743.23 mg/g. Kinetics and isotherm model fitting analysis revealed that the adsorption process of the composite hydrogel conformed to the pseudo-second-order kinetic model (R 2 > 0.999) and the Langmuir isotherm model (R 2 > 0.99), indicating that the adsorption process was dominated by chemisorption in a monolayer. Further FTIR and XPS characterization confirmed that the adsorption mechanism between the composite hydrogel and MB primarily involves: 1) electrostatic interactions between carboxyl groups in CA-β-CD and hydrogel chains with MB; 2) host-guest inclusion interactions between the hydrophobic cavities of β-CD and MB; 3) hydrogen bonding between the abundant hydroxyl and amino groups in β-CD, PAA, and PAM segments and MB, which plays a crucial role throughout the adsorption process. The thermodynamic parameters (ΔG < 0, ΔH < 0, ΔS < 0) indicate that the adsorption process of MB by the composite hydrogel is a spontaneous exothermic reaction, accompanied by a decrease in system entropy. Cyclic adsorption performance testing revealed that after 10 cycles, the R value for MB adsorption by the composite hydrogel remained around 92.33%, demonstrating promising application potential in dye wastewater treatment. Declarations Declaration of competing interest The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. Author Contribution **Ayiguzaili Abudiwayiti:** Investigation, Data curation, Writing-original draft. **Amatjan Sawu** t: Conceptualization, Supervision, Writing-review & editing, Funding acquisition, Project administration. **Rena Simayi** : Conceptualization, Writing-review & editing. **Long Cheng** : Investigation. Acknowledgement This study is financially supported by This study was financially supported by Natural Science Foundation of Xinjiang Uygur Autonomous Region (No. 2022D01C22). We sincerely appreciate the support. Data Availability Data will be made available on request. References Franciski MA, Peres EC, Godinho M et al (2018) Development of CO2 activated biochar from solid wastes of a beer industry and its application for methylene blue adsorption. Waste Manag 78:630–638. https://doi.org/10.1016/j.wasman.2018.06.040 Tushar KS, Sharmeen A, Ang HM et al (2010) Equilibrium, Kinetics and Mechanism of Removal of Methylene Blue from Aqueous Solution by Adsorption onto Pine Cone Biomass of Pinus radiata. Water Air Soil Pollut 218:499–515. https://doi.org/10.1007/s11270-010-0663-y He T, Hua J, Chen R, Yu L (2021) Adsorption characteristics of methylene blue by a dye-degrading and extracellular polymeric substance -producing strain. J Environ Manage 288:112446. https://doi.org/10.1016/j.jenvman.2021.112446 Li Y, Wang Y, Liu L, Tian L (2023) Non-radical-dominated catalytic degradation of methylene blue by magnetic CoMoO 4 /CoFe 2 O 4 composite peroxymonosulfate activators. J Environ Manage 325:116587. https://doi.org/10.1016/j.jenvman.2022.116587 Repon MR, Dev B, Rahman MA et al (2024) Textile dyeing using natural mordants and dyes: a review. Environ Chem Lett 22:1473–1520. https://doi.org/10.1007/s10311-024-01716-4 Guesmi Y, Agougui H, Lafi R et al (2018) Synthesis of hydroxyapatite-sodium alginate via a co-precipitation technique for efficient adsorption of Methylene Blue dye. J Mol Liq 249:912–920. https://doi.org/10.1016/j.molliq.2017.11.113 Chen H, Zhang YJ, He PY et al (2020) Coupling of self-supporting geopolymer membrane with intercepted Cr (III) for dye wastewater treatment by hybrid photocatalysis and membrane separation. Appl Surf Sci 515:146024. https://doi.org/10.1016/j.apsusc.2020.146024 Mishra S, Cheng L, Maiti A (2021) The utilization of agro-biomass/byproducts for effective bio-removal of dyes from dyeing wastewater: A comprehensive review. J Environ Chem Eng 9:104901. https://doi.org/10.1016/j.jece.2020.104901 Shiming X, Qiang L, Dongxu J et al (2020) Experimental investigation on dye wastewater treatment with reverse electrodialysis reactor powered by salinity gradient energy. Desalination 495:114541. https://doi.org/10.1016/j.desal.2020.114541 Patra BR, Nanda S, Dalai AK, Meda V (2021) Taguchi-based process optimization for activation of agro-food waste biochar and performance test for dye adsorption. Chemosphere 285:131531. https://doi.org/10.1016/j.chemosphere.2021.131531 Chen H, Zhou Y, Wang J et al (2020) Polydopamine modified cyclodextrin polymer as efficient adsorbent for removing cationic dyes and Cu 2+ . J Hazard Mater 389:121897. https://doi.org/10.1016/j.jhazmat.2019.121897 Safarzadeh H, Peighambardoust SJ, Mousavi SH et al (2022) Adsorption ability evaluation of the poly (methacrylic acid-co-acrylamide)/cloisite 30B nanocomposite hydrogel as a new adsorbent for cationic dye removal. Environ Res 212:113349. https://doi.org/10.1016/j.envres.2022.113349 Ben Moshe S, Furman A (2022) Real-time monitoring of organic contaminant adsorption in activated carbon filters using spectral induced polarization. Water Res 212:118103. https://doi.org/10.1016/j.watres.2022.118103 Yuan Y, Zhang Q, Lin S, Li J (2025) Water: The soul of hydrogels. Prog Mater Sci 148:101378. https://doi.org/10.1016/j.pmatsci.2024.101378 Oviedo LR, Oviedo VR, Nora LDD et al (2023) Adsorption of organic dyes onto nano-zeolites: A machine learning study. Sep Purif Technol 315:123712. https://doi.org/10.1016/j.seppur.2023.123712 Radoor S, Karayil J, Jayakumar A et al (2024) Recent advances in cellulose- and alginate-based hydrogels for water and wastewater treatment: A review. Carbohydr Polym 323:121339. https://doi.org/10.1016/j.carbpol.2023.121339 Zou X, Liu H, Hu Z et al (2025) Rational design of antifreeze and flexible chitosan-based hydrogels for integration device of supercapacitors electrodes and wearable strain sensors. Carbohydr Polym 354:123342. https://doi.org/10.1016/j.carbpol.2025.123342 Shalla AH, Bhat MA, Yaseen Z (2018) Hydrogels for removal of recalcitrant organic dyes: A conceptual overview. J Environ Chem Eng 6:5938–5949. https://doi.org/10.1016/j.jece.2018.08.063 Guo Y, Guo R, Shi X et al (2022) Synthesis of cellulose-based superabsorbent hydrogel with high salt tolerance for soil conditioning. Int J Biol Macromol 209:1169–1178. https://doi.org/10.1016/j.ijbiomac.2022.04.039 Liu Q, Zhou Y, Lu J, Zhou Y (2020) Novel cyclodextrin-based adsorbents for removing pollutants from wastewater: A critical review. Chemosphere 241:125043. https://doi.org/10.1016/j.chemosphere.2019.125043 Morin-Crini N, Crini G (2013) Environmental applications of water-insoluble β-cyclodextrin–epichlorohydrin polymers. Prog Polym Sci 38:344–368. https://doi.org/10.1016/j.progpolymsci.2012.06.005 Alsbaiee A, Smith BJ, Xiao L et al (2016) Rapid removal of organic micropollutants from water by a porous β-cyclodextrin polymer. Nature 529:190–194. https://doi.org/10.1038/nature16185 Nkinahamira F, Alsbaiee A, Zeng Q et al (2020) Selective and fast recovery of rare earth elements from industrial wastewater by porous β-cyclodextrin and magnetic β-cyclodextrin polymers. Water Res 181:115857. https://doi.org/10.1016/j.watres.2020.115857 Xiao Z, Xu Z, Zhou L et al (2025) Application of cyclodextrin-based microcapsules in food flavors and fragrances. Carbohydr Polym 367:123963. https://doi.org/10.1016/j.carbpol.2025.123963 Zhao J, Zou Z, Ren R et al (2018) Chitosan adsorbent reinforced with citric acid modified β-cyclodextrin for highly efficient removal of dyes from reactive dyeing effluents. Eur Polymer J 108:212–218. https://doi.org/10.1016/j.eurpolymj.2018.08.044 Zheng M, Lian F, Zhu Y et al (2019) pH-responsive poly (xanthan gum-g-acrylamide-g-acrylic acid) hydrogel: Preparation, characterization, and application. Carbohydr Polym 210:38–46. https://doi.org/10.1016/j.carbpol.2019.01.052 Zhao D, Zhao L, Zhu C et al (2009) Synthesis and properties of water-insoluble β-cyclodextrin polymer crosslinked by citric acid with PEG-400 as modifier. Carbohydr Polym 78:125–130. https://doi.org/10.1016/j.carbpol.2009.04.022 Hafiz Rozaini MN, Saad B, Lim JW et al (2022) Competitive removal mechanism to simultaneously incarcerate bisphenol A, triclosan and 4-tert-octylphenol within beta-cyclodextrin crosslinked citric acid used for encapsulation in polypropylene membrane protected-micro-solid-phase extraction. Chemosphere 309:136626. https://doi.org/10.1016/j.chemosphere.2022.136626 Hafiz Rozaini MN, Saad B, Lim JW et al (2022) Development of β-cyclodextrin crosslinked citric acid encapsulated in polypropylene membrane protected-µ-solid-phase extraction device for enhancing the separation and preconcentration of endocrine disruptor compounds. Chemosphere 303:135075. https://doi.org/10.1016/j.chemosphere.2022.135075 Mondal S, Baghel K, Cho S et al (2025) Efficient removal of amine-modified polystyrene nano-plastics utilizing poly(N-isopropylacrylamide)-sodium carboxymethyl cellulose hydrogel beads: Parametric optimization and mechanistic insights. Sep Purif Technol 363:132035. https://doi.org/10.1016/j.seppur.2025.132035 Wang W, Wang J, Zhao Y et al (2020) High-performance two-dimensional montmorillonite supported-poly (acrylamide-co-acrylic acid) hydrogel for dye removal. Environ Pollut 257:113574. https://doi.org/10.1016/j.envpol.2019.113574 Liang Y, Hou D, Ni Z et al (2022) Preparation, characterization of naringenin, β-cyclodextrin and carbon quantum dot antioxidant nanocomposites. Food Chem 375:131646. https://doi.org/10.1016/j.foodchem.2021.131646 Huang W, Hu Y, Li Y et al (2018) Citric acid-crosslinked β-cyclodextrin for simultaneous removal of bisphenol A, methylene blue and copper: The roles of cavity and surface functional groups. J Taiwan Inst Chem Eng 82:189–197. https://doi.org/10.1016/j.jtice.2017.11.021 Zhao F, Repo E, Yin D et al (2015) EDTA-Cross-Linked β-Cyclodextrin: An Environmentally Friendly Bifunctional Adsorbent for Simultaneous Adsorption of Metals and Cationic Dyes. Environ Sci Technol 49:10570–10580. https://doi.org/10.1021/acs.est.5b02227 Zhao B, Jiang H, Lin Z et al (2019) Preparation of acrylamide/acrylic acid cellulose hydrogels for the adsorption of heavy metal ions. Carbohydr Polym 224:115022. https://doi.org/10.1016/j.carbpol.2019.115022 Wang Y, Yang N, Wang D et al (2018) Poly (MAH-β-cyclodextrin-co-NIPAAm) hydrogels with drug hosting and thermo/pH-sensitive for controlled drug release. Polym Degrad Stab 147:123–131. https://doi.org/10.1016/j.polymdegradstab.2017.11.023 Soe HMSH, Junthip J, Chamni S et al (2023) A promising synthetic citric crosslinked β-cyclodextrin derivative for antifungal drugs: Solubilization, cytotoxicity, and antifungal activity. Int J Pharm 645:123394. https://doi.org/10.1016/j.ijpharm.2023.123394 García-Fernández MJ, Tabary N, Martel B et al (2013) Poly-(cyclo)dextrins as ethoxzolamide carriers in ophthalmic solutions and in contact lenses. Carbohydr Polym 98:1343–1352. https://doi.org/10.1016/j.carbpol.2013.08.003 Malik NS, Ahmad M, Minhas MU (2017) Cross-linked β-cyclodextrin and carboxymethyl cellulose hydrogels for controlled drug delivery of acyclovir. PLoS ONE 12:e0172727. .https://doi.org/10.1371/journal.pone.0172727 Li W, Liu H, Li L, Liu K, Liu J, Tang T, Jiang W (2019) Green Synthesis of Citric Acid-Crosslinked β-Cyclodextrin for Highly Efficient Removal of Uranium (VI) from Aqueous Solution. J Radioanal Nucl Chem 322:2033–2042. https://doi.org/10.1007/s10967-019-06901-2 Altayan MM, Tzoupanos N, Barjenbruch M (2023) Polymer based on beta-cyclodextrin for the removal of bisphenol A, methylene blue and lead (II): Preparation, characterization, and investigation of adsorption capacity. J Mol Liq 390:122822. https://doi.org/10.1016/j.molliq.2023.122822 Wang X, Wang Y, Hou H et al (2017) Ultrasonic Method to Synthesize Glucan-g-poly (acrylic acid)/Sodium Lignosulfonate Hydrogels and Studies of Their Adsorption of Cu 2+ from Aqueous Solution. ACS Sustainable Chem Eng 5:6438–6446. https://doi.org/10.1021/acssuschemeng.7b00332 Eltaweil AS, Elgarhy GS, El-Subruiti GM, Omer AM (2020) Carboxymethyl cellulose/carboxylated graphene oxide composite microbeads for efficient adsorption of cationic methylene blue dye. Int J Biol Macromol 154:307–318. https://doi.org/10.1016/j.ijbiomac.2020.03.122 Zhang M, Hou S, Li Y et al (2022) Swelling characterization of ionic responsive superabsorbent resin containing carboxylate sodium groups. Reactive Funct Polym 170:105144. https://doi.org/10.1016/j.reactfunctpolym.2021.105144 Wan X, Rong Z, Zhu K, Wu Y (2022) Chitosan-based dual network composite hydrogel for efficient adsorption of methylene blue dye. Int J Biol Macromol 222:725–735. https://doi.org/10.1016/j.ijbiomac.2022.09.213 Hosseini H, Zirakjou A, McClements DJ et al (2022) Removal of methylene blue from wastewater using ternary nanocomposite aerogel systems: Carboxymethyl cellulose grafted by polyacrylic acid and decorated with graphene oxide. J Hazard Mater 421:126752. https://doi.org/10.1016/j.jhazmat.2021.126752 Zhang Y, Wei H, Hua B et al (2024) Preparation and application of the thermo-/pH–/ ion-sensitive semi-IPN hydrogel based on chitosan. Int J Biol Macromol 258:128968. https://doi.org/10.1016/j.ijbiomac.2023.128968 Adel M, Ahmed MA, Mohamed AA (2021) Synthesis and characterization of magnetically separable and recyclable crumbled MgFe 2 O 4 /reduced graphene oxide nanoparticles for removal of methylene blue dye from aqueous solutions. J Phys Chem Solids 149:109760. https://doi.org/10.1016/j.jpcs.2020.109760 Tran TH, Le AH, Pham TH et al (2020) Adsorption isotherms and kinetic modeling of methylene blue dye onto a carbonaceous hydrochar adsorbent derived from coffee husk waste. Sci Total Environ 725:138325. https://doi.org/10.1016/j.scitotenv.2020.138325 Zhang P, O’Connor D, Wang Y et al (2020) A green biochar/iron oxide composite for methylene blue removal. J Hazard Mater 384:121286. https://doi.org/10.1016/j.jhazmat.2019.121286 Mohamed AK, Mahmoud ME (2020) Nanoscale Pisum sativum pods biochar encapsulated starch hydrogel: A novel nano-sorbent for efficient chromium (VI) ions and naproxen drug removal. Bioresour Technol 308:123263. https://doi.org/10.1016/j.biortech.2020.123263 Ai T, Jiang X, Liu Q et al (2019) Daptomycin adsorption on magnetic ultra-fine wood-based biochars from water: Kinetics, isotherms, and mechanism studies. Bioresour Technol 273:8–15. https://doi.org/10.1016/j.biortech.2018.10.039 Singha NR, Mahapatra M, Karmakar M et al (2017) Synthesis of guar gum-g-(acrylic acid-co-acrylamide-co-3-acrylamido propanoic acid) IPN via in situ attachment of acrylamido propanoic acid for analyzing superadsorption mechanism of Pb (II)/Cd (II)/Cu (II)/MB/MV. Polym Chem 8:6750–6777. https://doi.org/10.1039/C7PY01564J Wan X, Rong Z, Zhu K, Wu Y (2022) Chitosan-based dual network composite hydrogel for efficient adsorption of methylene blue dye. Int J Biol Macromol 222:725–735. https://doi.org/10.1016/j.ijbiomac.2022.09.213 Hussain S, Salman M, Youngblood JP et al (2024) Enhanced adsorption of Congo red dye by CS/PEG/ZnO composite hydrogel: Synthesis, characterization, and performance evaluation. J Mol Liq 411:125704. https://doi.org/10.1016/j.molliq.2024.125704 Sari Yilmaz M (2022) Graphene oxide/hollow mesoporous silica composite for selective adsorption of methylene blue. Microporous Mesoporous Mater 330:111570. https://doi.org/10.1016/j.micromeso.2021.111570 Zhang Y, Wang P, Hussain Z et al (2022) Modification and characterization of hydrogel beads and its used as environmentally friendly adsorbent for the removal of reactive dyes. J Clean Prod 342:130789. https://doi.org/10.1016/j.jclepro.2022.130789 Ovchinnikov OV, Evtukhova AV, Kondratenko TS et al (2016) Manifestation of intermolecular interactions in FTIR spectra of methylene blue molecules. Vib Spectrosc 86:181–189. https://doi.org/10.1016/j.vibspec.2016.06.016 Pang J, Fu F, Ding Z et al (2017) Adsorption behaviors of methylene blue from aqueous solution on mesoporous birnessite. J Taiwan Inst Chem Eng 77:168–176. https://doi.org/10.1016/j.jtice.2017.04.041 Shen Y, Ni W-X, Li B (2021) Porous Organic Polymer Synthesized by Green Diazo-Coupling Reaction for Adsorptive Removal of Methylene Blue. ACS Omega 6:3202–3208. https://doi.org/10.1021/acsomega.0c05634 Li K, Yan J, Zhou Y et al (2021) β-cyclodextrin and magnetic graphene oxide modified porous composite hydrogel as a superabsorbent for adsorption cationic dyes: Adsorption performance, adsorption mechanism and hydrogel column process investigates. J Mol Liq 335:116291. https://doi.org/10.1016/j.molliq.2021.116291 Wang W, Wang J, Zhao Y et al (2020) High-performance two-dimensional montmorillonite supported-poly (acrylamide-co-acrylic acid) hydrogel for dye removal. Environ Pollut 257:113574. https://doi.org/10.1016/j.envpol.2019.113574 Mallard I, Landy D, Fourmentin S (2020) Evaluation of polyethylene glycol crosslinked β-CD polymers for the removal of methylene blue. Appl Sci 10:4679. https://doi.org/10.3390/app10134679 Jurado-López B, Vieira RS, Rabelo RB et al (2017) Formation of complexes between functionalized chitosan membranes and copper: A study by angle resolved XPS. Mater Chem Phys 185:152–161. https://doi.org/10.1016/j.matchemphys.2016.10.018 Chen P, Cao Z, Wen X et al (2017) A novel mesoporous silicate material (MS) preparation from dolomite and enhancing methylene blue removal by electronic induction. J Taiwan Inst Chem Eng 80:128–136. https://doi.org/10.1016/j.jtice.2017.08.044 Wu H, Kong J, Yao X et al (2015) Polydopamine-assisted attachment of β-cyclodextrin on porous electrospun fibers for water purification under highly basic condition. Chem Eng J 270:101–109. https://doi.org/10.1016/j.cej.2015.02.019 Zhu J, Luo Y, Wang J et al (2022) Highly efficient uranium extraction by aminated lignin-based thermo-responsive hydrogels. J Mol Liq 368:120744. https://doi.org/10.1016/j.molliq.2022.120744 Additional Declarations No competing interests reported. Supplementary Files SupportingInformationAYG2.12.docx GraphicalAbstract213.jpg Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 28 Apr, 2026 Reviews received at journal 12 Apr, 2026 Reviewers agreed at journal 31 Mar, 2026 Reviewers invited by journal 24 Mar, 2026 Editor assigned by journal 19 Feb, 2026 Submission checks completed at journal 19 Feb, 2026 First submitted to journal 13 Feb, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8874053","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":611239688,"identity":"5972fff8-0974-46e5-858a-108756ffaf9b","order_by":0,"name":"Ayiguzaili Abudiwayiti","email":"","orcid":"","institution":"State Key Laboratory of Chemistry and Utilization of Carbon Based Energy Resources; College of Chemistry, Xinjiang University","correspondingAuthor":false,"prefix":"","firstName":"Ayiguzaili","middleName":"","lastName":"Abudiwayiti","suffix":""},{"id":611239689,"identity":"ab3b5c8d-d84a-4b3c-8099-7e708d74f24f","order_by":1,"name":"Amatjan Sawut","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA+0lEQVRIiWNgGAWjYLACCRjjAwMbiDIgpIGxAaqFsXEG0VpgjGYeCAO/Fv5ph58/sKi5Y88/I8f8sW0bX2IDe/M2CYaaOzi1SNxOM2yQOPYsccaNHMPmnDNsiQ08x8okGI49w23N7QSgFrbDCQy3QVoqgFokcswkGBsO49Qhfzv9Y4PEv8P28iAtFgZALfJv8GsxAKpskGw7zLgBpIUBbAsPfi2Gt3MKZ0j2HU7ceP9Z4cyeM2zGbTxpxRYJx3BrkbudvuGzxLfD9nJnDm/48LPtmGw/++GNNz7U4NYCAswSCPYxSGQm4NUAjMIPCHYNAbWjYBSMglEwEgEAPRVYlFwqaOUAAAAASUVORK5CYII=","orcid":"","institution":"State Key Laboratory of Chemistry and Utilization of Carbon Based Energy Resources; College of Chemistry, Xinjiang University","correspondingAuthor":true,"prefix":"","firstName":"Amatjan","middleName":"","lastName":"Sawut","suffix":""},{"id":611239691,"identity":"d62336ef-f140-4184-acf5-89052167d6e4","order_by":2,"name":"Rena Simayi","email":"","orcid":"","institution":"College of Chemical Engineering and Technology, Xinjiang University","correspondingAuthor":false,"prefix":"","firstName":"Rena","middleName":"","lastName":"Simayi","suffix":""},{"id":611239692,"identity":"b1a4e2a2-54e1-48a0-9fa4-cd537c0227e9","order_by":3,"name":"Long Cheng","email":"","orcid":"","institution":"College of Chemical Engineering and Technology, Xinjiang University","correspondingAuthor":false,"prefix":"","firstName":"Long","middleName":"","lastName":"Cheng","suffix":""}],"badges":[],"createdAt":"2026-02-13 16:39:25","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8874053/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8874053/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":105447387,"identity":"f56158d0-ba79-4ca4-a7d1-906545656d77","added_by":"auto","created_at":"2026-03-26 07:27:42","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":430767,"visible":true,"origin":"","legend":"\u003cp\u003eSchematic flow diagrams of the preparation of (a) CA-β-CD and (b) CA-β-CD/P(AA-co-AM)\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-8874053/v1/a99099ab36e51b635624416b.png"},{"id":105447362,"identity":"5dc8cebb-fe22-4797-a602-24b04a59bc3a","added_by":"auto","created_at":"2026-03-26 07:27:27","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":370813,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Mechanism of CA-β-CD preparation and (b) CA-β-CD/P(AA-co-AM) preparation\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-8874053/v1/5ce6b9b7fcac3597d7ddbb20.png"},{"id":105447345,"identity":"5fc82656-68a4-411f-aad9-7a9329ee74ca","added_by":"auto","created_at":"2026-03-26 07:27:14","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":587259,"visible":true,"origin":"","legend":"\u003cp\u003e(A) FTIR spectra of β-CD, CA, CA-β-CD, and CA-β-CD/P(AA-co-AM); (B) \u003csup\u003e1\u003c/sup\u003eH NMR spectra of β-CD and CA-β-CD; (C) TGA curves of β-CD, CA-β-CD, and CA-β-CD/P(AA-co-AM)\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-8874053/v1/871b643f711a775ffa6b6395.png"},{"id":105447358,"identity":"afead167-966e-4868-8f15-5787e92f152e","added_by":"auto","created_at":"2026-03-26 07:27:26","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":990260,"visible":true,"origin":"","legend":"\u003cp\u003eSEM images of CA-β-CD/P(AA-co-AM): (A) before adsorption, (B) after adsorption; (C) MAPPING and EDS before adsorption; (D) MAPPING and EDS after adsorption\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-8874053/v1/170b0f3089ba2e87a88324b9.png"},{"id":105447361,"identity":"f473fcfe-4249-44a6-8619-344e5dbc524d","added_by":"auto","created_at":"2026-03-26 07:27:27","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":655181,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of CA-β-CD/P(AA-co-AM) on MB adsorption performance: (A) Comparison of adsorption capacities among different adsorbents; (B) Swelling performance test; (C) Adsorption time; (D) Different initial concentrations; (E) Different ionic strengths; (F) Dose of CA-β-CD/P(AA-co-AM); (G) pH; (H) Temperature; (I) Thermodynamic fitting curve; (Experimental conditions: composite hydrogel mass m = 10 mg, MB dye solution volume V = 25 mL, initial concentration c = 1000 mg/L, adsorption time t = 4 h, agitation speed 130 rpm)\u003c/p\u003e","description":"","filename":"floatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-8874053/v1/e5c630a270e200d34cb151ce.png"},{"id":105447342,"identity":"34c023a0-6352-4e9e-8e25-51321ae45fab","added_by":"auto","created_at":"2026-03-26 07:27:14","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":531749,"visible":true,"origin":"","legend":"\u003cp\u003e(A) Reusability performance of the composite hydrogel; (D) Adsorption capacity of the composite hydrogel for different dyes; Binary dye adsorption experiments: (B) MO/MB; (C) CR/MB; (E) MO/MG; (F) CR/MG\u003c/p\u003e","description":"","filename":"floatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-8874053/v1/b080a33d0d61637666a2315c.png"},{"id":105447389,"identity":"66df77d7-3d69-4518-967f-5bcb7826a98c","added_by":"auto","created_at":"2026-03-26 07:27:42","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":379988,"visible":true,"origin":"","legend":"\u003cp\u003e(A) Langmuir Isotherm Models; (B) Freundlich Isotherm Models; (C) Temkin Isotherm Models; (D) Intra-particle Diffusion Model; (E) PFO Kinetic Model; (F) PSO Kinetic Model\u003c/p\u003e","description":"","filename":"floatimage7.png","url":"https://assets-eu.researchsquare.com/files/rs-8874053/v1/cbad80c158f0244dc19f544a.png"},{"id":105447409,"identity":"58023b20-4968-47d8-bae3-ea11a16eff08","added_by":"auto","created_at":"2026-03-26 07:27:46","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":564889,"visible":true,"origin":"","legend":"\u003cp\u003eAdsorption Mechanism and Characterization of Composite Hydrogel: (A) Schematic diagram of adsorption mechanism; (B) FTIR spectra before and after adsorption; (C) Full XPS spectra before and after adsorption; (D–F) Pre-adsorption spectra: (D) C 1s, (E) N 1s, (F) O 1s; (G–I) Post-adsorption spectra: (G) C 1s, (H) N 1s, (I) O 1s\u003c/p\u003e","description":"","filename":"floatimage8.png","url":"https://assets-eu.researchsquare.com/files/rs-8874053/v1/789bfc20fde94e72d6ebe7f6.png"},{"id":105447539,"identity":"34859612-e3a6-4513-92fb-951ee417f139","added_by":"auto","created_at":"2026-03-26 07:28:17","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":5791745,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8874053/v1/3bf0b667-96e8-4bc5-9ecb-43d364059818.pdf"},{"id":105447357,"identity":"d61bfd82-b453-402e-9f00-27985d494208","added_by":"auto","created_at":"2026-03-26 07:27:26","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":1430858,"visible":true,"origin":"","legend":"","description":"","filename":"SupportingInformationAYG2.12.docx","url":"https://assets-eu.researchsquare.com/files/rs-8874053/v1/b31b61bf17383b432bd4a1ea.docx"},{"id":105447405,"identity":"c02513c4-a8b4-4e04-a0f2-42809231cff2","added_by":"auto","created_at":"2026-03-26 07:27:43","extension":"jpg","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":997548,"visible":true,"origin":"","legend":"","description":"","filename":"GraphicalAbstract213.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8874053/v1/c23b7db96ab2968270e17d22.jpg"}],"financialInterests":"No competing interests reported.","formattedTitle":"Preparation of citric acid-modified β-cyclodextrin/poly (acrylic acid-co- acrylamide) composite hydrogel for enhanced methylene blue adsorption","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eWater scarcity and pollution have evolved into pressing global challenges, and synthetic dye contamination\u0026mdash;primarily originating from textile, printing, and dyeing industries\u0026mdash;poses particularly severe threats to aquatic ecosystems and human health [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Studies indicate that approximately 5\u0026ndash;10% of these industrially produced dyes are discharged into aquatic systems through untreated or partially treated wastewater[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e], exacerbating concerns about long-term environmental degradation and ecological imbalance. Common organic dyes in industrial effluents include methylene blue (MB), methyl orange (MO), methyl green (MG), basic fuchsine (BF), and Congo red (CR). Among this group, MB stands out as a typical cationic thiazine dye, finding extensive application across industrial manufacturing, chemical synthesis, and medical/surgical fields\u0026mdash;such as textile coloring, reagent preparation, and tissue staining [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Despite its utility, MB exhibits high toxicity even at trace levels: concentrations as low as 0.1\u0026ndash;10 mg/L can disrupt algal photosynthesis (a key link in aquatic food chains), induce DNA damage in aquatic organisms, and cause adverse effects in humans\u0026mdash;including skin irritation, eye damage, and potential neurological disorders [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. These risks underscore the urgency of developing efficient, eco-friendly technologies for MB removal from aqueous systems to safeguard environmental sustainability.\u003c/p\u003e \u003cp\u003eExisting dye treatment technologies vary in efficacy and limitations. Chemical oxidation degrades MB but requires harsh conditions (e.g., strong acidity) and generates toxic byproducts [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e], while membrane filtration suffers from frequent fouling and high operational costs that restrict large-scale use [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Biological degradation, though eco-friendly, is highly sensitive to temperature and pH fluctuations, often requiring 24\u0026ndash;72 hours to achieve moderate removal rates [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Electrodialysis, while effective for dye separation, is hampered by high energy consumption and sensitivity to feedwater salinity\u0026mdash;factors that increase operational costs and limit its applicability in low-salinity dye wastewater treatment [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Adsorption stands out among these methods for its simplicity, low energy consumption, and adaptability to diverse water matrices [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e], yet traditional adsorbents like activated carbon (high cost), clay minerals (low capacity, \u0026lt;\u0026thinsp;100 mg/g), and biomass materials (poor structural stability) fail to meet the demands of high-efficiency dye treatment [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. This gap has driven research toward advanced adsorbents with tailored structures and multifunctional properties.\u003c/p\u003e \u003cp\u003eHydrogels\u0026mdash;three-dimensional cross-linked polymer networks capable of absorbing large volumes of water while retaining shape\u0026mdash;have emerged as promising candidates for dye adsorption. [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e] Their porous architecture ensures rapid dye molecule diffusion, and their surface chemistry can be adjusted to introduce active binding sites [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. Natural polymer hydrogels (e.g., chitosan, alginate, cellulose) offer biocompatibility but suffer from weak mechanical strength and limited adsorption capacity [\u003cspan additionalcitationids=\"CR16\" citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. Synthetic hydrogels like poly(acrylic acid-co-acrylamide) (P(AA-co-AM)) exhibit better stability but rely primarily on electrostatic attraction and hydrogen bonding for dye binding, resulting in low selectivity and capacity [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. To address these shortcomings, researchers have integrated macrocyclic compounds into hydrogel matrices [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e], with β-cyclodextrin (β-CD) drawing particular interest [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. As a cyclic oligosaccharide composed of seven glucose units, β-CD features a hydrophobic internal cavity that forms stable inclusion complexes with MB via hydrophobic interactions, enhancing adsorption selectivity [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. However, native β-CD has critical limitations: poor water solubility leads to agglomeration in hydrogels, a single adsorption mechanism (only host-guest inclusion) restricts capacity [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e], and the absence of cross-linking sites makes it difficult to form stable bonds with polymer networks [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. Traditional β-CD modifiers (e.g., epichlorohydrin, maleic anhydride) are toxic and require complex synthesis processes, creating a need for green, low-cost modification strategies [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eTo address these challenges, we first synthesized CA-β-CD oligomer using CA as a modifier; this CA-β-CD was subsequently incorporated into the P(AA-co-AM) network to form the CA-β-CD/P(AA-co-AM) composite hydrogel. We hypothesized that: (1) CA-based modification of β-CD would introduce additional carboxyl groups, optimize its cavity structure, promote β-CD oligomerization, and thereby overcome the inherent solubility and functional limitations of native β-CD; (2) integrating host\u0026ndash;guest active CA-β-CD with a robust P(AA-co-AM) matrix would create a synergistic hydrogel system that significantly enhances both the adsorption capacity and selectivity toward methylene blue (MB). To verify these hypotheses, the structures and properties of CA-β-CD and the composite hydrogel were thoroughly characterized. The adsorption performance of the composite hydrogel was systematically evaluated and compared with that of unmodified P(AA-co-AM) hydrogels under same conditions. This study provides a green and efficient strategy for constructing high-performance β-cyclodextrin-based adsorbents and highlights the potential of natural polysaccharide composites in treating organic dye-contaminated wastewater.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e"},{"header":"2. Materials and methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Experimental materials and apparatus\u003c/h2\u003e \u003cp\u003eAcrylic acid (AA, \u0026gt;\u0026thinsp;99%) was purchased procured Shandong Keyuan Bio-chemical Co., Ltd.; Acrylamide (AM, 99%) and 2-hydroxy-4'-(2-hydroxyethoxy)-2-methyl-propiophenone (PI) were purchased from Shanghai McLean Biochemical Technology Co., Ltd.; Citric acid (CA, 99%), N,N'-Methylenebisacrylamide (MBA, 99.5%), and anhydrous ethanol were acquired from Tianjin Zhiyuan Chemical Reagent Co., Ltd.; β-cyclodextrin (β-CD, \u0026ge;\u0026thinsp;98%) was purchased from Shanghai Qingxi Chemical Technology Co., Ltd.; Methylene blue (MB, \u0026ge;\u0026thinsp;98.5%), sodium hypophosphite (99%), and methyl orange (MO) were purchased from Tianjin Yongsheng Fine Chemical Co., Ltd.; Methyl green (MG) was purchased from Sinno Group Chemical Reagent Co., Ltd.; Congo Red (CR) was purchased from Tianjin Damiao Chemical Reagent Factory; Phenolphthalein was procured from Tianjin Shengmiao Fine Chemical Co., Ltd.; While sodium hydroxide (NaOH) was obtained from Tianjin Xinbote Chemical Co., Ltd.; The UV-Vis spectrophotometer was acquired from Shanghai Jinghua Technology Instrument Co., Ltd.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Preparation of CA-β-CD\u003c/h2\u003e \u003cp\u003eCA-β-CD was synthesized using the hydrothermal method, modified based on the reported procedure [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. Dissolve 2.52 g of NaH\u003csub\u003e2\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e and 23.05 g of CA in 20 mL of ultrapure water with stirring. Add 11.35 g of β-CD to the solution and stir until dissolved. The mixture should then be transferred to a reaction vessel and placed in a vacuum drying oven. Heat at 100\u0026deg;C for 1 hour, then increase the temperature to 120\u0026deg;C. leave to react for 6 hours. After the reaction, cool to room temperature. Slowly add the mixture dropwise to anhydrous ethanol to precipitate a white solid. Vacuum filtration, wash multiple times, and dry under vacuum at 60\u0026deg;C for 24 hours to obtain CA-β-CD. The preparation process is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea:\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3 Preparation of CA-β-CD/P(AA-co-AM) composite hydrogels\u003c/h2\u003e \u003cp\u003eFirst, weigh 2 g of CA-β-CD and dissolve it in 40 mL of distilled water with stirring. Dissolve 2.6 g of AM in 10 mL of distilled water. Once dissolved, slowly add this solution to the CA-β-CD solution while stirring to form a transparent Solution A. Neutralize 2.5 mL of AA solution using 5 M NaOH solution. Prepare AA solutions with different neutralization degrees, mix them thoroughly, and cool to room temperature. Subsequently, sequentially add 0.12 g of MBA and 0.08 g of PI mixed solution. After ultrasonic treatment for 10 min, obtain a uniform solution B. Calculate the neutralization degree according to Eq.\u0026nbsp;\u003cspan refid=\"Equ1\" class=\"InternalRef\"\u003e1\u003c/span\u003e [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e\u003cimg src=\"data:image/png;base64,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\" width=\"664\" height=\"67\"\u003e\u003c/p\u003e\u003cp\u003eIn the equation, a represents the neutralization degree of AA (%); b denotes the volume of NaOH (L); m\u003csub\u003eAA\u003c/sub\u003e indicates the weight of AA (g).\u003c/p\u003e \u003cp\u003eMeasure 5, 10, 15, 20 and 25 mL of Solution A separately, mix each with Solution B, and sonicate for 5 minutes. Transfer the mixture to a specific mold (quartz glass plate, 10\u0026times;10\u0026times;2 cm), irradiate under UV light for 5 min to initiate polymerization, forming a gel. Wash the gel, dry at 70\u0026deg;C for 24 hours, grind, and sieve through a 40\u0026ndash;60 mesh screen. Store in sealed sample bags for future use. The composite hydrogel synthesis is schematically illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb:\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e2.4 Determination of β-CD and carboxyl content in CA-β-CD\u003c/h2\u003e \u003cp\u003eThe number of active carboxyl groups in CA-β-CD was determined by titration using 0.01 M HCl solution [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. Active β-CD was quantified via phenolphthalein titration [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. see the supporting information for details.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e2.5 Characterization of CA-β-CD and CA-β-CD/P(AA-co-AM)\u003c/h2\u003e \u003cp\u003eFourier transform infrared (FT-IR) spectra of the samples were obtained using a VERTEX 70 RAMI (Bruker). X-ray photoelectron spectroscopy (XPS) data were acquired using an ESCALAB 250 Xi (Thermo Fisher Scientific). The microstructure of the samples was examined using a scanning electron microscopy (SEM, JSM-7001F, Japan). Thermal stability was evaluated using thermogravimetric-differential thermal analysis (TGA) (Hitachi STA7300, Japan). The hydrogen nuclear magnetic resonance (\u003csup\u003e1\u003c/sup\u003eH NMR) spectra of β-CD and CA-β-CD were acquired on a Bruker AVANCE NEO 600.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003e2.6 Swelling performance testing\u003c/h2\u003e \u003cp\u003eWeigh 0.1 g of the composite hydrogel and place it in 100 mL of distilled water for swelling performance testing. At predetermined time intervals, remove the swollen composite hydrogel, blot residual surface moisture with filter paper, and weigh it. Calculate the swelling degree (SD) according to Eq.\u0026nbsp;\u003cspan refid=\"Equ2\" class=\"InternalRef\"\u003e2\u003c/span\u003e:\u003cdiv id=\"Equ2\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ2\" name=\"EquationSource\"\u003e\n$$\\:\\text{SD=}\\frac{\\left({\\text{w}}_{\\text{t}}\\text{-}{\\text{w}}_{\\text{0}}\\right)}{{\\text{w}}_{\\text{0}}}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e2\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eIn the equation, W\u003csub\u003et\u003c/sub\u003e denotes the mass of the swollen hydrogel at time t (g); W\u003csub\u003e0\u003c/sub\u003e denotes the initial mass of the composite hydrogel (g).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003e2.7 Adsorption performance testing\u003c/h2\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eThis study investigates the adsorption performance of composite hydrogels toward MB. Precisely weigh 10 mg of composite hydrogel and add it to 25 mL of MB solution. Shake the mixture at 130 rpm in a shaker at room temperature for 240 minutes to achieve adsorption equilibrium. To ensure adsorption saturation, the supernatant was removed and diluted to 25 mL. The MB concentration was measured using a UV-visible spectrophotometer. Additionally, the effects of adsorbent dosage, initial dye concentration, pH, temperature, and various ions on adsorption performance were investigated. All experiments were conducted in triplicate, and the results represent the average values. The adsorption capacity Q\u003csub\u003ee\u003c/sub\u003e, total adsorption Q\u003csub\u003et\u003c/sub\u003e, and removal efficiency R (%) of the composite hydrogel were calculated according to Eqs.\u0026nbsp;\u003cspan refid=\"Equ3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, \u003cspan refid=\"Equ4\" class=\"InternalRef\"\u003e4\u003c/span\u003e, and \u003cspan refid=\"Equ5\" class=\"InternalRef\"\u003e5\u003c/span\u003e, respectively [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e].\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Equ3\" class=\"Equation\"\u003e \u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ3\" name=\"EquationSource\"\u003e\n$$\\:{\\text{Q}}_{\\text{e}}\\text{=}\\frac{\\left({\\text{C}}_{\\text{0}}\\text{-Ce}\\right)\\text{\u0026times;V}}{\\text{m}}$$\u003c/div\u003e \u003cdiv class=\"EquationNumber\"\u003e3\u003c/div\u003e\u003c/div\u003e \u003cdiv id=\"Equ4\" class=\"Equation\"\u003e \u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ4\" name=\"EquationSource\"\u003e\n$$\\:{\\text{Q}}_{\\text{t}}\\text{=}\\frac{\\left({\\text{C}}_{\\text{0}}\\text{-}{\\text{C}}_{\\text{e}}\\right)\\text{\u0026times;V}}{\\text{m}}$$\u003c/div\u003e \u003cdiv class=\"EquationNumber\"\u003e4\u003c/div\u003e\u003c/div\u003e \u003cdiv id=\"Equ5\" class=\"Equation\"\u003e \u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ5\" name=\"EquationSource\"\u003e\n$$\\:\\text{R=}\\frac{{\\text{C}}_{\\text{0}}\\text{-}{C}_{e}}{{\\text{C}}_{\\text{0}}}\\text{\u0026times;100%}$$\u003c/div\u003e \u003cdiv class=\"EquationNumber\"\u003e5\u003c/div\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eIn the equation, Q\u003csub\u003ee\u003c/sub\u003e and Q\u003csub\u003et\u003c/sub\u003e represent adsorption capacity (mg/g); R denotes removal efficiency (%); The initial concentration of MB is denoted by C\u003csub\u003e0\u003c/sub\u003e (mg/L), whilst C\u003csub\u003ee\u003c/sub\u003e and C\u003csub\u003et\u003c/sub\u003e represent the MB concentrations at adsorption equilibrium (mg/L); The volume of MB used is denoted by V (L), and m is the mass of the composite hydrogel (g).\u003c/p\u003e \u003cdiv id=\"Sec10\" class=\"Section3\"\u003e \u003ch2\u003e2.7.1 MB standard curve\u003c/h2\u003e \u003cp\u003eA series of MB solutions with concentrations ranging from 3 to 8 mg/L were prepared. Absorbance was measured at the maximum absorption wavelength of 664 nm, and a standard curve for MB was plotted (Fig. S4a). The experimental results demonstrated a good linear relationship between absorbance and MB concentration, with the linear regression equation being y\u0026thinsp;=\u0026thinsp;8.9721x\u0026thinsp;\u0026minus;\u0026thinsp;0.2577 (R\u003csup\u003e2\u003c/sup\u003e= 0.9997).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section3\"\u003e \u003ch2\u003e2.7.2 Selective adsorption of different dyes\u003c/h2\u003e \u003cp\u003eIn practical wastewater treatment, dyes typically exist as mixtures. To accurately investigate the selectivity of composite hydrogels, this study designed adsorption experiments using a binary anionic/cationic dye system. Representative cationic dyes MB and MG, along with anionic dyes CR and MO, were first selected for adsorption testing. Subsequently, mixed dye solutions (CR/MB, MO/MB, CR/MG, MO/MG) were prepared for adsorption testing.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003e2.8 Adsorption kinetics and isotherm studies\u003c/h2\u003e \u003cp\u003eIn adsorption kinetics experiments, composite hydrogels were added to MB solutions. After varying durations, adsorption was halted, MB concentrations were measured, and kinetic curves were plotted. Composite hydrogels were added to MB solutions of different concentrations for 12 hours of adsorption to ensure adsorption saturation before plotting adsorption isotherms.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003e2.9 Cycle performance testing\u003c/h2\u003e \u003cp\u003eThe potential cyclic performance of the composite hydrogel was evaluated through 10 adsorption-desorption cycles. In each cycle, the composite hydrogel was first placed in a methylene blue solution for adsorption saturation, then filtered out and desorbed in a mixed oxalic acid-anhydrous ethanol eluent. Residual eluent was rinsed off with distilled water before conducting the cyclic test.\u003c/p\u003e \u003c/div\u003e"},{"header":"3. Results and discussion","content":"\u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003e3.1 Mechanism of composite hydrogel preparation\u003c/h2\u003e \u003cp\u003eUnder acidic conditions at a high temperature, the carboxyl group in CA undergoes protonation to form a highly electrophilic intermediate (CA-COOH\u0026thinsp;+\u0026thinsp;H⁺ ⇌ CA-C⁺(OH)\u003csub\u003e2\u003c/sub\u003e). the oxygen atom on β-CD-OH acts as a nucleophile, attacking the carbonyl carbon of the protonated carboxyl group. This reaction results in the elimination of one water molecule and the formation of an ester bond (β-CD-OH\u0026thinsp;+\u0026thinsp;CA-C⁺(OH)\u003csub\u003e2\u003c/sub\u003e \u0026rarr; β-CD-O-C(=\u0026thinsp;O)-CA\u0026thinsp;+\u0026thinsp;H\u003csub\u003e2\u003c/sub\u003eO\u0026thinsp;+\u0026thinsp;H⁺) [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e], yielding the cross-linked polymer CA-β-CD (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea). Under UV irradiation, the C-C bond between the aliphatic carbon and the carbonyl group in the photo-initiator (PI) breaks to generate P\u0026middot; and I\u0026middot; radicals [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e], which reacts with the C\u0026thinsp;=\u0026thinsp;C bonds in the AA/AM monomers to initiate chain growth and generate polymer radicals (C-C-C-C\u003cb\u003e\u0026middot;\u003c/b\u003e, C-C-C-C-C-C-C\u003cb\u003e\u0026middot;\u003c/b\u003e\u0026hellip;). These radicals then react with MBA to form a three-dimensionally crosslinked P(AA-co-AM) polymer [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. This network combines with CA-β-CD polymers to form CA-β-CD/P(AA-co-AM) composite hydrogels (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eb).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec16\" class=\"Section2\"\u003e \u003ch2\u003e3.2 Structural characterization and analysis\u003c/h2\u003e \u003cp\u003eThe FTIR spectra of β-CD, CA, CA-β-CD, and CA-β-CD/P(AA-co-AM) are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e(A).The β-CD exhibits a -OH stretching vibration peak at 3385 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and an asymmetric methylene (CH\u003csub\u003e2\u003c/sub\u003e) stretching vibration peak at 2932 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]\u003csup\u003e\u0026minus;\u003c/sup\u003e[\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]. Absorption peaks at 1654 and 1407 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e correspond to -OH bending vibrations, while peaks at 941, 1029, and 1157 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e represent α-1,4-glycosidic backbone vibrations, C\u0026thinsp;=\u0026thinsp;O, and C-OH stretching vibrations of β-CD [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e],[\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]. CA-β-CD exhibits an -OH stretching vibration peak at 3425 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and the ester group (carboxyl) stretching peak at 1743 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, indicating esterification between β-CD's -OH and CA's carboxyl group [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Meanwhile, characteristic vibration peaks at 2932, 1163, and 1029 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e corresponding to C-H, C-O-C, and C-O bonds of the β-CD sugar ring structure remain intact, indicating that the β-CD backbone retains its integrity during crosslinking [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]\u003csup\u003e,\u003c/sup\u003e[\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]. This provides preliminary evidence for the successful modification of β-CD. CA-β-CD/P(AA-co-AM) exhibits -OH and N-H stretching vibration peaks at 3547 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, while the peaks at 1682 and 1562 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e correspond to C\u0026thinsp;=\u0026thinsp;O stretching in AA and amide group (C-N) stretching in AM [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e]. These results confirm the successful preparation of CA-β-CD/P(AA-co-AM).\u003c/p\u003e \u003cp\u003eThe \u003csup\u003e1\u003c/sup\u003eH NMR spectra of β-CD and CA-β-CD are presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eB. In the case of β-CD (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eB a), the signals for Ha and Hb appear at δ 5.68 ppm, the peak for Hc appears at 4.41 ppm, the characteristic peak for H\u003csub\u003e1\u003c/sub\u003e appears at δ 4.84 ppm, and the characteristic peaks for H\u003csub\u003e2\u003c/sub\u003e\u0026ndash;H\u003csub\u003e6\u003c/sub\u003e appear in the range of δ 3.32\u0026ndash;δ 3.64 ppm [\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e]. All chemical shifts are referenced to the D\u003csub\u003e2\u003c/sub\u003eO solvent peak (δ 4.79 ppm). In CA-β-CD (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eB b), the H\u003csub\u003e1\u003c/sub\u003e signal from the β-CD pyranose glucose unit appears at δ 5.06 ppm, while signals for H\u003csub\u003e2\u003c/sub\u003e\u0026ndash;H\u003csub\u003e6\u003c/sub\u003e appear in the range δ 3.63\u0026ndash;3.98 ppm. The ester protons (B) appeared at δ 4.63\u0026ndash;4.66 ppm [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e]. The methylene protons (A) in the CA crosslinker peaked at δ 2.82\u0026ndash;2.98 ppm, while two single peaks at δ 6.60 and δ 7.47 ppm (labeled C and D, respectively) corresponded to cis- and trans-aconitic acid ester structures [\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e]. This result is consistent with the characteristics of the FTIR spectrum, which confirms the successful modification.\u003c/p\u003e \u003cp\u003eTo ascertain the thermal stability of the composite hydrogel, thermogravimetric analysis (TGA) was performed on β-CD, CA-β-CD, and CA-β-CD/P(AA-co-AM) (see Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eC). The thermal decomposition of β-CD occurred at temperatures below 100\u0026deg;C, resulting in a weight loss of around 12%, This was primarily due to water evaporation from the surface or cavities of the β-CD. Between 100\u0026ndash;360\u0026deg;C, significant weight loss of approximately 65.17% occurred, corresponding to the thermal decomposition of β-CD's macrocyclic structure [\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e]. At 360\u0026ndash;500\u0026deg;C, the final residue rate reached 13.28%. CA-β-CD exhibited approximately 13.49% weight loss below 200\u0026deg;C, attributed to water evaporation from the polymer surface [\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e]. Between 250\u0026ndash;360\u0026deg;C, weight loss reached about 48%, indicating decomposition of the polymer backbone structure. After 500\u0026deg;C, the residual rate was approximately 28.52%, demonstrating that crosslinking effectively enhanced thermal stability. CA-β-CD/P(AA-co-AM) exhibits a 10% weight loss below 200\u0026deg;C, attributed to water evaporation from the composite hydrogel. Between 200\u0026ndash;436\u0026deg;C, the weight loss reaches approximately 16.64%, resulting from the decomposition of organic acids, β-CD macrocycles [\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e], decomposition of carboxyl and amide groups [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e], and main-chain breakage [\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e], resulting in a final residue rate of 52.85%. CA-β-CD/P(AA-co-AM) exhibits excellent thermal stability.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eTo investigate the effect of chemical modification on the microstructure of the material, morphological analysis of β-CD and CA-β-CD was performed using SEM (Fig. S3). In comparison to the conventional plate-like structure of β-CD, CA-β-CD exhibited an agglomerate structure with a rough surface and a multitude of pores, further confirming the successful modification of β-CD. Figure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e illustrates the SEM, MAPPING and EDS results of the composite hydrogel before and after MB adsorption. Pre-adsorption (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eA a-c) samples exhibited a porous structure with interconnected macropores and surface micropores/wrinkles. The high porosity and rough surface provided abundant adsorption sites for MB. Post-adsorption (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eB d-f), the morphology underwent significant changes: pores were filled, channels became denser, and pore sizes decreased, indicating successful adsorption of MB into the gel pores and onto its surface. This phenomenon is attributed to the competitive adsorption of MB and water molecules on the gel surface, which weakens the repulsive forces between polymer chains through electrostatic interactions, leading to pore size contraction during swelling. Further analysis via MAPPING and EDS before and after adsorption (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eC-D) reveals a significant increase in S content with uniform distribution post-adsorption, confirming that MB has uniformly coated the hydrogel surface.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe total acid group (TA) content in CA-β-CD was determined to be 4 mmol/g by titration reflecting the combined amount of carboxyl and ester groups. the β-CD cavity content (TC) was determined to be 0.366 mmol/g, phenolphthalein titration, with a degree of substitution (DS) of 1.56. Based on the β-CD calibration curve (Fig. \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e, y\u0026thinsp;=\u0026thinsp;0.64576\u0026ndash;0.03339x, R\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.9984), it was found that phenolphthalein was able to embed into the hydrophobic cavity of β-CD under alkaline conditions, resulting in decreased absorbance. This indicates that CA-β-CD successfully retained the cavity structure of β-CD [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. Therefore, the abundant total acidic groups in CA-β-CD and the β-CD cavity structure synergistically provide numerous adsorption sites for various dye molecules [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. The gel permeation chromatography (GPC) results shown in Fig. S2 indicate that the CA-β-CD weight-average molecular weight (Mw) is 8.935 kDa and the polydispersity index (PDI) is 1.79. This polymer formation aligns with the step-growth polymerization mechanism and demonstrates characteristics of a soluble macromolecular crosslinking agent. These results are consistent with FTIR and titration data, collectively confirming the successful synthesis of the CA-β-CD polymer.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec17\" class=\"Section2\"\u003e \u003ch2\u003e3.3 Adsorption experiment of CA-β-CD/P(AA-co-AM)\u003c/h2\u003e \u003cdiv id=\"Sec18\" class=\"Section3\"\u003e \u003ch2\u003e3.3.1 Single-factor experiment\u003c/h2\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eThe study examines how reaction parameters affect the adsorption performance of CA-β-CD/P(AA-co-AM). These parameters include the molar ratio of CA and β-CD, reaction time, AA neutralization degree, MBA dosage and CA-β-CD loading amount. The results are shown in Fig. S4. The optimal preparation conditions, as determined by single-factor optimization, were as follows: CA: β-CD molar ratio of 1:12, reaction time of 6 hours, neutralization degree of 85%, MBA dosage of 0.12 g, and CA-β-CD loading of 0.2 g. The hydrogel obtained under these combined conditions exhibited the best adsorption performance. Detailed analysis in the supporting information.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec19\" class=\"Section2\"\u003e \u003ch2\u003e3.4 Performance testing of CA-β-CD/P(AA-co-AM)\u003c/h2\u003e \u003cdiv id=\"Sec20\" class=\"Section3\"\u003e \u003ch2\u003e3.4.1 Swelling performance testing\u003c/h2\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eA indicates that CA-β-CD/P(AA-co-AM) exhibits the highest adsorption capacity for MB, with a Qe value of 2353.08 mg/g, surpassing both the P(AA-co-AM) hydrogel (2080.75 mg/g) and β-CD (13.34 mg/g). In swelling performance tests (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eB), CA-β-CD/P(AA-co-AM) rapidly swelled in both media. Its adsorption capacity (Q\u003csub\u003eeq\u003c/sub\u003e) in distilled water was 198.05 g/g, primarily due to ionization of hydrophilic groups releasing Na⁺ and -COO⁻ ions. This fully expanded the three-dimensional network structure. The osmotic pressure difference between the interior and exterior of the gel facilitated rapid water absorption. By contrast, in a 0.9% NaCl solution, Q\u003csub\u003eeq\u003c/sub\u003e was 52.08 g/g. Within the NaCl solution, Na⁺ ions shielded the electrostatic repulsion between -COO⁻ groups, limiting the expansion of the hydrogel network. This reduced osmotic pressure difference consequently restricted swelling capacity.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec21\" class=\"Section3\"\u003e \u003ch2\u003e3.4.2 Effect of adsorption time on MB adsorption performance\u003c/h2\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eThe composite hydrogel demonstrated an increase in adsorption capacity for MB over time, as illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eC. with increase in adsorption time, the Q\u003csub\u003ee\u003c/sub\u003e exhibited a gradual rise, reaching adsorption equilibrium at 4 h with a Q\u003csub\u003ee\u003c/sub\u003e of 2353.08 mg/g. The extension of the adsorption time to 12 h resulted in a marginal increase in Q\u003csub\u003ee\u003c/sub\u003e, further confirming the attainment of adsorption equilibrium.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec22\" class=\"Section3\"\u003e \u003ch2\u003e3.4.3 Effect of initial MB concentration\u003c/h2\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eThe present study investigates the potential application of CA-β-CD/P(AA-co-AM) in wastewater containing different concentrations of dye. Figure\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eD shows how the initial MB concentration (100\u0026ndash;3000 mg/L) affects its adsorption performance. As the MB concentration increased from 100 mg/L to 3000 mg/L, the Q\u003csub\u003ee\u003c/sub\u003e of the composite hydrogel rose from 243.56 mg/g to 5061.21 mg/g. The collision frequency between the dye and the adsorbent surface increased with rising concentration, thereby promoting the adsorption process. However, When the MB concentration was increased further, the growth of Q\u003csub\u003ee\u003c/sub\u003e gradually slowed down. This was attributed to the fixed dosage of the adsorbent and the limited number of active adsorption sites on its surface, which were approaching saturation [\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e].\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec23\" class=\"Section3\"\u003e \u003ch2\u003e3.4.4 Effect of different ion strengths on MB adsorption performance\u003c/h2\u003e \u003cp\u003eMultiple ions present in actual wastewater affect the adsorption performance. The influence of metal cations at different valence states (Na\u003csup\u003e+\u003c/sup\u003e, Ca\u003csup\u003e2+\u003c/sup\u003e, Fe\u003csup\u003e3+\u003c/sup\u003e) on the adsorption performance of CA-β-CD/P(AA-co-AM) was investigated (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eE). As ion concentration increased, the Q\u003csub\u003ee\u003c/sub\u003e of MB gradually decreased, with Na⁺ exhibiting the least impact and Fe\u003csup\u003e3+\u003c/sup\u003e having the greatest effect. Reasons for Q\u003csub\u003ee\u003c/sub\u003e decrease: Metal ions compete with MB for adsorption sites while forming complexes with -COO⁻ groups in the composite hydrogel network [\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e], increasing crosslink density and weakening electrostatic repulsion between molecular chains. This restricts the expansion of the three-dimensional network. Furthermore, the addition of ions reduces osmotic pressure within the hydrogel, hindering MB adsorption. Higher ion valence intensifies competition, leading to decreased MB adsorption capacity with increasing metal ion valence [\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e].\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec24\" class=\"Section3\"\u003e \u003ch2\u003e3.4.5 Effect of composite hydrogel dosage on MB adsorption performance\u003c/h2\u003e \u003cp\u003eThe amount of adsorbent is a key parameter affecting the adsorption performance of composite hydrogels (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eF). Increasing the adsorbent dosage from 5 to 25 mg caused a decrease in the Q\u003csub\u003ee\u003c/sub\u003e from 3040.47 to 979.52 mg/g and an increase in R value from 60.81% to 97.95%. As the dosage of adsorbent increases, so dose the number of active sites utilized in the system, but these remains unsaturated. This leads to reduced utilization efficiency and consequently lower adsorption capacity [\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e, \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e]. At an adsorbent dosage of 10 mg, Q\u003csub\u003ee\u003c/sub\u003e reached 2353.08 mg/g and R achieved 93.40%. Taking into account both adsorption performance and cost-effectiveness, subsequent experiments selected 10 mg as the optimal dosage for the composite hydrogel.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec25\" class=\"Section3\"\u003e \u003ch2\u003e3.4.6 Effect of different pH levels on MB adsorption performance\u003c/h2\u003e \u003cp\u003eTo investigate the effect of pH on the performance of MB adsorption, 10 mg of composite hydrogel was added to the MB solution and the Q\u003csub\u003ee\u003c/sub\u003e and R values were measured at different pH levels, The results are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eG. The Qe of MB adsorption by the composite hydrogel increased with rising pH. Under acidic conditions (pH\u0026thinsp;\u0026lt;\u0026thinsp;5), both the adsorption capacity and efficiency were low. This was primarily due to abundant H⁺ ions in the solution competing for adsorption sites with MB, while the carboxyl groups in the composite hydrogel underwent protonation, converting to -COOH. This conversion weakened the electrostatic adsorption interaction with MB molecules [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. As pH increases, adsorption performance improves. Decreased H⁺ concentration enhances the negative charge density on the adsorbent surface, converting -COOH groups in the composite hydrogel to -COO⁻ [\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e], thereby strengthening electrostatic adsorption capacity toward MB [\u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e].\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec26\" class=\"Section3\"\u003e \u003ch2\u003e3.4.7 Effect of temperature on MB adsorption performance\u003c/h2\u003e \u003cp\u003eTemperature is one of the key factors that influence adsorption performance. To investigate the adsorption efficiency of composite hydrogels toward MB at different temperatures, a systematic study was conducted within the range of 25 to 75\u0026deg;C (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eH). As the temperature increased from 25 to 75\u0026deg;C, the Q\u003csub\u003ee\u003c/sub\u003e of MB adsorption by the composite hydrogel decreased from 2353.08 to 1932.92 mg/g, and the R decreased from 93.40% to 77.31%. This suggests that elevated temperatures are detrimental to effective MB adsorption. The adsorption process is a thermally active reaction [\u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e]. Increased temperature may induce contraction of the composite hydrogel network structure, thereby reducing the probability of contact between MB molecules. Concurrently, it impedes the adsorption reaction, resulting in reductions in Q\u003csub\u003ee\u003c/sub\u003e and R.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec27\" class=\"Section3\"\u003e \u003ch2\u003e3.4.8 Adsorption thermodynamics\u003c/h2\u003e \u003cp\u003eDuring the adsorption process, changes in thermodynamic parameters are crucial factors for studying the adsorption performance of composite hydrogels. Thermodynamic parameters such as Gibbs free energy change (ΔG), enthalpy change (ΔH), and entropy change (ΔS) were calculated using Eqs.\u0026nbsp;\u003cspan refid=\"Equ6\" class=\"InternalRef\"\u003e6\u003c/span\u003e, \u003cspan refid=\"Equ7\" class=\"InternalRef\"\u003e7\u003c/span\u003e, and \u003cspan refid=\"Equ8\" class=\"InternalRef\"\u003e8\u003c/span\u003e, systematically analyzing the energy variation patterns of composite hydrogels during adsorption.\u003cdiv id=\"Equ6\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ6\" name=\"EquationSource\"\u003e\n$$\\:\\text{Ln}\\left(\\frac{\\text{Qe}}{{\\text{C}}_{\\text{e}}}\\right)\\text{=}\\frac{\\text{\u0026Delta;S}}{\\text{R}}\\text{-}\\frac{\\text{\u0026Delta;H}}{\\text{RT}}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e6\u003c/div\u003e\u003c/div\u003e\u003cdiv id=\"Equ7\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ7\" name=\"EquationSource\"\u003e\n$$\\:\\text{\u0026Delta;G=\u0026Delta;H-T\u0026Delta;S}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e7\u003c/div\u003e\u003c/div\u003e\u003cdiv id=\"Equ8\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ8\" name=\"EquationSource\"\u003e\n$$\\:\\text{\u0026Delta;}\\text{G=-RT}\\text{ln}\\left(\\frac{\\text{Qe}}{\\text{Ce}}\\right)$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e8\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eIn the equation, R is the ideal gas constant (8.314 J/mol K); T is the temperature in kelvins (K); C\u003csub\u003ee\u003c/sub\u003e is the equilibrium concentration of MB (mg/L). By plotting the curve of ln (Q\u003csub\u003ee\u003c/sub\u003e/C\u003csub\u003ee\u003c/sub\u003e) versus 1/T (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eI), a good linear relationship is observed.\u003c/p\u003e \u003cp\u003eThe thermodynamic parameters of the adsorption process are listed in Table \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e. All ΔG values are negative (-8.8365 to -6.2017 kJ/mol), indicating that the adsorption process is spontaneous [\u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e51\u003c/span\u003e]. The negative ΔH value of (-23.9866 kJ/mol) indicates that the adsorption of MB by the composite hydrogel is an exothermic process, reflecting its favorable thermodynamic adsorption properties. Furthermore, the negative ΔS value (-51.7721 J/mol K) reflects a reduction in degrees of freedom at the solid/liquid interface during adsorption, indicating enhanced molecular order [\u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e52\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec28\" class=\"Section2\"\u003e \u003ch2\u003e3.5 Experiments on the selectivity of CA-β-CD/P(AA-co-AM) toward different dyes\u003c/h2\u003e \u003cdiv id=\"Sec29\" class=\"Section3\"\u003e \u003ch2\u003e3.5.1 Testing the cycling performance of composite hydrogels\u003c/h2\u003e \u003cp\u003eTo investigate the reusability of the composite hydrogel, 10 consecutive adsorption-desorption cycles were conducted (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003eA). As the number of cycles increased, the R value decreased from 98.20% to 92.33%, yet the hydrogel retained a certain adsorption capacity, demonstrating promising potential for cyclic application in contaminated water systems. The decline in R primarily resulted from strong electrostatic or hydrogen bonding interactions forming between some MB molecules and the hydrogel, firmly occupying active sites and making complete desorption difficult during the desorption process. This led to a gradual reduction in effective adsorption sites [\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe comparative Q\u003csub\u003ee\u003c/sub\u003e values of the composite hydrogel for four dyes are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003eD, revealing distinct adsorption capacities for different dyes. MB exhibited the highest Qe (2353.08 mg/g), followed by MG (1442.22 mg/g) and MO (731.06 mg/g), while CR showed the lowest Qe of only 166.81 mg/g. To further investigate adsorption selectivity, experiments were conducted with mixed dye systems (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003eB, C, E, F). In the MO/MB mixture, MB exhibits characteristic absorption peaks at 664 nm and 612 nm, corresponding to its monomer and dimer forms, respectively. These dimers self-assemble via face-to-face interactions mediated by π\u0026ndash;π stacking and hydrogen bonding [\u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAs the adsorption time extended from 1 h to 6 h, the intensity of the MB absorption peak decreased, while the peak intensity of MO at 465 nm showed minimal change. The peak intensity of CR at 500 nm remained essentially constant over time, whereas the characteristic absorption peak intensity of MG at 633 nm exhibited a marked decrease over time. The composite hydrogel exhibits high selective adsorption toward cationic dyes. This selectivity arises from the effective interactions between the cationic dyes and functional groups within the composite hydrogel. These include the abundant carboxyl groups in AA and CA-β-CD, the amino groups on the AM segments, and the hydroxyl groups in the cyclodextrin. These interactions occur via electrostatic forces, hydrogen bonding, and host-guest interactions, thereby enabling selective adsorption of the cationic dyes.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec30\" class=\"Section2\"\u003e \u003ch2\u003e3.6 Adsorption isotherms of CA-β-CD/P(AA-co-AM)\u003c/h2\u003e \u003cp\u003eTo thoroughly investigate the adsorption process of composite hydrogels, experimental data were systematically analyzed using three adsorption isotherm models: Langmuir, Freundlich, and Temkin.\u003c/p\u003e \u003cp\u003eThe Langmuir adsorption isotherm is expressed as Eq.\u0026nbsp;\u003cspan refid=\"Equ9\" class=\"InternalRef\"\u003e9\u003c/span\u003e [\u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e54\u003c/span\u003e]:\u003cdiv id=\"Equ9\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ9\" name=\"EquationSource\"\u003e\n$$\\:{\\text{Q}}_{\\text{e}}\\text{=}\\frac{{\\text{K}}_{\\text{L\\:}}{\\text{Q}}_{\\text{m}}\\text{}{\\text{C}}_{\\text{e}}}{\\text{1+}{\\text{K}}_{\\text{L\\:}}\\text{}{\\text{C}}_{\\text{e}}}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e9\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eIn the equation, Q\u003csub\u003ee\u003c/sub\u003e representative of the equilibrium adsorption capacity (mg/g); C\u003csub\u003ee\u003c/sub\u003e denotes the dye concentration at adsorption equilibrium (mg/L); Qₘ indicates the maximum adsorption capacity (mg/g) and K\u003csub\u003eL\u003c/sub\u003e is the Langmuir adsorption constant (L/mg). Based on the linear fitting results presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003eA and Table S2, the composite hydrogel exhibits a Q\u003csub\u003em\u003c/sub\u003e of 3743.23 mg/g for MB and a K\u003csub\u003eL\u003c/sub\u003e value of 0.02381 L/mg.\u003c/p\u003e \u003cp\u003eThe separation factor (R\u003csub\u003eL\u003c/sub\u003e) is a dimensionless parameter used to assess the ease of adsorption processes on Langmuir isotherms, defined by Eq.\u0026nbsp;\u003cspan refid=\"Equ10\" class=\"InternalRef\"\u003e10\u003c/span\u003e:\u003cdiv id=\"Equ10\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ10\" name=\"EquationSource\"\u003e\n$$\\:{\\text{R}}_{\\text{L}}\\text{=}\\frac{\\text{1}}{\\text{1+}{\\text{C}}_{\\text{0}}{\\text{k}}_{\\text{L}}}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e10\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eThe value of R\u003csub\u003eL\u003c/sub\u003e is closely related to the adsorption process. When R\u003csub\u003eL\u003c/sub\u003e \u0026gt; 1, adsorption is unfavorable. When R\u003csub\u003eL\u003c/sub\u003e = 1, adsorption is linear. When 0\u0026thinsp;\u0026lt;\u0026thinsp;R\u003csub\u003eL\u003c/sub\u003e \u0026lt; 1, adsorption is easily initiated and a higher R\u003csub\u003eL\u003c/sub\u003e value within this range promotes the reaction; R\u003csub\u003eL\u003c/sub\u003e = 0 signifies an irreversible adsorption reaction. The calculated R\u003csub\u003eL\u003c/sub\u003e values in this study range from 0.01381 to 0.2958, falling within the (0\u0026thinsp;\u0026lt;\u0026thinsp;R\u003csub\u003eL\u003c/sub\u003e \u0026lt; 1) interval. This indicates that the adsorption process proceeds in a favorable direction.\u003c/p\u003e \u003cp\u003eThe Freundlich adsorption isotherm is expressed as Eq.\u0026nbsp;\u003cspan refid=\"Equ11\" class=\"InternalRef\"\u003e11\u003c/span\u003e [\u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e54\u003c/span\u003e]:\u003cdiv id=\"Equ11\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ11\" name=\"EquationSource\"\u003e\n$$\\:\\text{Ln}{\\text{Q}}_{\\text{e}}\\text{=}\\frac{\\text{1}}{\\text{n}}\\text{ln}{\\text{C}}_{\\text{e}}\\text{+}\\text{ln}{\\text{k}}_{\\text{f}}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e11\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eIn the equation, K\u003csub\u003ef\u003c/sub\u003e represents the Freundlich adsorption constant (L/mg); 1/n characterizes the heterogeneity factor of the adsorbent surface. A higher K\u003csub\u003ef\u003c/sub\u003e value indicates superior adsorption performance of the composite hydrogel, while a value closer to 0 reflects stronger surface heterogeneity. Conversely, a value closer to 1 suggests the adsorption process is chemisorption. Based on the fitting results in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003eB and Table S2, this study calculated 1/n\u0026thinsp;=\u0026thinsp;0.45799, indicating a heterogeneous adsorption process, with K\u003csub\u003ef\u003c/sub\u003e = 217.78 L/mg.\u003c/p\u003e \u003cp\u003eThe Temkin adsorption isotherm is expressed as Eq.\u0026nbsp;\u003cspan refid=\"Equ12\" class=\"InternalRef\"\u003e12\u003c/span\u003e [\u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e54\u003c/span\u003e]:\u003cdiv id=\"Equ12\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ12\" name=\"EquationSource\"\u003e\n$$\\:{\\text{Q}}_{\\text{e}}\\text{=}\\frac{\\text{RT}}{{\\text{b}}_{\\text{T}}}\\text{ln}{\\text{C}}_{\\text{e}}\\text{+}\\frac{\\text{RT}}{{\\text{b}}_{\\text{T}}}\\text{ln}{\\text{A}}_{\\text{T}}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e12\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eIn the equation, R is the ideal gas constant 8.314 J/ (mol K); T is the reaction temperature (K); b\u003csub\u003eT\u003c/sub\u003e is the Temkin constant (J/mol); A\u003csub\u003eT\u003c/sub\u003e is the Temkin isothermal constant (L/g). Based on the linear fitting results from Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003eC and Table S2, b\u003csub\u003eT\u003c/sub\u003e = 3.511 J/mol and A\u003csub\u003eT\u003c/sub\u003e = 0.352 L/g were calculated.\u003c/p\u003e \u003cp\u003eOf the Langmuir, Freundlich, and Temkin adsorption isotherm models, the Langmuir model (R\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.9989) provided the best fit, significantly outperforming the Freundlich model (R\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.9105) and the Temkin model (R\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.8864). This suggests that the adsorption process is more closely aligned with the Langmuir model, which represents single-layer chemisorption with uniformly distributed adsorption sites [\u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e55\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec31\" class=\"Section2\"\u003e \u003ch2\u003e3.7 Adsorption Kinetics of CA-β-CD/P(AA-co-AM)\u003c/h2\u003e \u003cp\u003eAdsorption kinetic parameters are considered to be pivotal in the evaluation of the adsorption performance of composite hydrogels. The adsorption process is analyzed using the following kinetic models: the pseudo-first-order (PFO), pseudo-second-order (PSO), and intra-particle diffusion models.\u003c/p\u003e \u003cp\u003eThe PFO kinetic model is expressed as Eq.\u0026nbsp;\u003cspan refid=\"Equ13\" class=\"InternalRef\"\u003e13\u003c/span\u003e:\u003cdiv id=\"Equ13\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ13\" name=\"EquationSource\"\u003e\n$$\\:\\text{Ln}\\left({\\text{Q}}_{\\text{e}}\\text{-}{\\text{Q}}_{\\text{t}}\\right)\\text{=}\\text{ln}{\\text{Q}}_{\\text{e}}\\text{-}{\\text{K}}_{\\text{1}}\\text{t}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e13\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eThe PSO kinetic model is shown in Eq.\u0026nbsp;\u003cspan refid=\"Equ14\" class=\"InternalRef\"\u003e14\u003c/span\u003e:\u003cdiv id=\"Equ14\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ14\" name=\"EquationSource\"\u003e\n$$\\:\\frac{\\text{T}}{\\text{Qt}}\\text{=}\\frac{\\text{t}}{{\\text{Q}}_{\\text{e}}}\\text{+}\\frac{\\text{1}}{{\\text{K}}_{\\text{2}}{\\text{Q}}_{\\text{e}}^{\\text{2}}}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e14\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eThe intra-particle diffusion model is shown in Eq.\u0026nbsp;\u003cspan refid=\"Equ15\" class=\"InternalRef\"\u003e15\u003c/span\u003e:\u003cdiv id=\"Equ15\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ15\" name=\"EquationSource\"\u003e\n$$\\:{\\text{Q}}_{\\text{t}}\\text{=}{\\text{k}}_{\\text{i}}{\\text{t}}^{\\raisebox{1ex}{$\\text{1}$}\\!\\left/\\:\\!\\raisebox{-1ex}{$\\text{2}$}\\right.}\\text{+}{\\text{C}}_{\\text{I}}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e15\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eIn the equation, Q\u003csub\u003et\u003c/sub\u003e represents the adsorption amount at time t (mg/g); t denotes the adsorption time (min); k\u003csub\u003e1\u003c/sub\u003e is the pseudo-first-order adsorption rate constant (min\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e); k\u003csub\u003e2\u003c/sub\u003e is the pseudo-second-order adsorption rate constant g/ (mg min); k\u003csub\u003ei\u003c/sub\u003e is the intraparticle diffusion rate constant mg/ (g min\u003csup\u003e0.5\u003c/sup\u003e); C is the intraparticle diffusion model constant.\u003c/p\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e(E-F) displays the fitting curves for the PFO and PSO kinetic models, with corresponding data detailed in Table S3. The correlation coefficient (R\u003csup\u003e2\u003c/sup\u003e) for the PFO kinetic model is significantly lower than that for the PSO model, with the latter's R\u003csup\u003e2\u003c/sup\u003e approaching 1. The Q\u003csub\u003ee\u003c/sub\u003e values calculated from the PFO kinetic model differ significantly from the experimentally obtained Q\u003csub\u003eexp\u003c/sub\u003e values, indicating that the adsorption process better conforms to the PSO kinetic model. The adsorption mechanism is classified as chemical adsorption [\u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e56\u003c/span\u003e]. The fitting results and corresponding parameters for the intra-particle diffusion model are detailed in (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003eD, Table S4). All fitted lines did not pass through the origin and exhibited non-zero intercepts, indicating that a single independent mechanism does not dominate the MB adsorption process but rather results from the combined effects of surface adsorption and intra-particle diffusion [\u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e57\u003c/span\u003e]. The distinct intercepts observed on the vertical axis of the fitted curves further confirm that liquid film diffusion resistance significantly influences the adsorption rate [\u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e56\u003c/span\u003e].\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec32\" class=\"Section2\"\u003e \u003ch2\u003e3.8 Adsorption mechanism of CA-β-CD/P(AA-co-AM)\u003c/h2\u003e \u003cp\u003eTo investigate the adsorption mechanism of CA-β-CD/P(AA-co-AM) toward MB, FTIR and XPS characterization was performed on samples before and after adsorption. As shown in FTIR Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003eB, characteristic MB peaks appeared at 1600, 1394, 1489, 1139, 884, and 661 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, corresponding to the skeletal vibration of aromatic rings, the stretching vibration of -CH\u003csub\u003e3\u003c/sub\u003e, the bending vibration of -C\u0026thinsp;=\u0026thinsp;N, C-N, and aromatic C-H out-of-plane, and the vibration of C-S-C bonds [\u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e58\u003c/span\u003e, \u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e59\u003c/span\u003e], indicating successful MB adsorption onto the hydrogel surface [\u003cspan citationid=\"CR60\" class=\"CitationRef\"\u003e60\u003c/span\u003e]. Multiple characteristic peaks shifted, with the -OH and N-H stretching vibration peak moving from 3475 to 3448 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, suggesting hydrogen bond formation between MB and the hydrogel [\u003cspan citationid=\"CR61\" class=\"CitationRef\"\u003e61\u003c/span\u003e]. The C\u0026thinsp;=\u0026thinsp;O stretching vibration peak shifted from 1685 to 1768 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, with altered peak shape and intensity, indicating changes in the chemical environment around the carbonyl group. The C\u0026ndash;H stretching vibration peak shifted from 2947 to 2922 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, potentially forming C\u0026ndash;H⋯O\u0026thinsp;=\u0026thinsp;C or C\u0026ndash;H⋯N hydrogen bonds [\u003cspan citationid=\"CR62\" class=\"CitationRef\"\u003e62\u003c/span\u003e]. Additionally, electrostatic interactions exist between -COO- and -N(CH\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e in MB [\u003cspan citationid=\"CR63\" class=\"CitationRef\"\u003e63\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe full XPS spectrum (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003eC) reveals the presence of C, O, Na, S, and N elements in the composite hydrogel. Following adsorption, the intensity of the Na 1s peak decreased while that of the S 2p peak increased, indicating ion exchange [\u003cspan citationid=\"CR62\" class=\"CitationRef\"\u003e62\u003c/span\u003e]. In the C 1s spectrum (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003eD,G), pre-adsorption peaks at 283.52, 284.80, 286.70, and 287.80 eV correspond to C-C, C\u0026thinsp;=\u0026thinsp;C/C-C/C-H, C\u0026thinsp;=\u0026thinsp;O/C-O-C, and C\u0026thinsp;=\u0026thinsp;O functional groups [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. After adsorption, binding energy shifts occur, with C-O and C-S peaks appearing at 286.19 and 287.13 eV. In the N 1s spectrum (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003eE,H), pre-adsorption peaks at 398.43, 401.40, and 402.34 eV correspond to -NH\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e\u003cb\u003e+\u003c/b\u003e\u003c/sup\u003e, -C\u0026thinsp;=\u0026thinsp;N⁻, C-N, -NH\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e+\u003c/sup\u003e, -NH⁻, and -C\u0026thinsp;=\u0026thinsp;N⁻ in PAM [\u003cspan citationid=\"CR64\" class=\"CitationRef\"\u003e64\u003c/span\u003e]. After adsorption, peaks appear at 398.71 and 401.33 eV, corresponding to -N(CH\u003csub\u003e3\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e and O\u0026thinsp;=\u0026thinsp;C-N in MB [\u003cspan citationid=\"CR65\" class=\"CitationRef\"\u003e65\u003c/span\u003e]. The shift in binding energy further indicates hydrogen bonding interactions. The four peaks at 530.08, 531.2, 532.63, and 534.70 eV in the O 1s spectrum (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003eF,I) correspond sequentially to the O-C\u0026thinsp;=\u0026thinsp;O, -C\u0026thinsp;=\u0026thinsp;O, C-O, and -C\u0026thinsp;=\u0026thinsp;O bonds in CA-β-CD and PAA [\u003cspan citationid=\"CR66\" class=\"CitationRef\"\u003e66\u003c/span\u003e, \u003cspan citationid=\"CR67\" class=\"CitationRef\"\u003e67\u003c/span\u003e]. After adsorption, the binding energy shifts but no new peaks appear. The adsorption mechanism of the composite hydrogel (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003eA), The adsorption mechanism primarily involves: (1) electrostatic interactions between MB and -COO⁻ groups in PAA and CA-β-CD; (2) host-guest inclusion complex formation as MB enters the β-CD cavity; (3) hydrogen bonding between MB and numerous hydroxyl groups in PAA, PAM, and CA-β-CD. These synergistic interactions collectively enhance the adsorption performance of the composite hydrogel.\u003c/p\u003e \u003cp\u003eTo evaluate the adsorption performance of the composite hydrogel toward MB, it was compared with previously reported adsorbents in the literature. The results indicate that CA-β-CD/P(AA-co-AM) exhibits superior MB adsorption capacity compared to most adsorbents listed in Table S5.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"4. Conclusion","content":"\u003cp\u003eThis study successfully prepared a CA-β-CD/P(AA-co-AM) composite hydrogel with a porous network structure and abundant active groups by crosslinking CA with β-CD and copolymerizing it with AA and AM. The chemical structure, composition, and stability of the composite hydrogel were characterized using FTIR, \u003csup\u003e1\u003c/sup\u003eH NMR, TGA, XPS, and SEM, confirming the successful preparation of both CA-β-CD and CA-β-CD/P(AA-co-AM).\u003c/p\u003e \u003cp\u003eTo investigate the adsorption performance of CA-β-CD/P(AA-co-AM) towards MB, the study revealed that the adsorption process is influenced by solution pH, adsorbent dosage, initial MB concentration, adsorption time, and varying salt ion concentrations. Adsorption isotherm results demonstrated that the composite hydrogel exhibits excellent adsorption capacity for MB, with a maximum adsorption capacity reaching 3743.23 mg/g. Kinetics and isotherm model fitting analysis revealed that the adsorption process of the composite hydrogel conformed to the pseudo-second-order kinetic model (R\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.999) and the Langmuir isotherm model (R\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.99), indicating that the adsorption process was dominated by chemisorption in a monolayer. Further FTIR and XPS characterization confirmed that the adsorption mechanism between the composite hydrogel and MB primarily involves: 1) electrostatic interactions between carboxyl groups in CA-β-CD and hydrogel chains with MB; 2) host-guest inclusion interactions between the hydrophobic cavities of β-CD and MB; 3) hydrogen bonding between the abundant hydroxyl and amino groups in β-CD, PAA, and PAM segments and MB, which plays a crucial role throughout the adsorption process.\u003c/p\u003e \u003cp\u003eThe thermodynamic parameters (ΔG\u0026thinsp;\u0026lt;\u0026thinsp;0, ΔH\u0026thinsp;\u0026lt;\u0026thinsp;0, ΔS\u0026thinsp;\u0026lt;\u0026thinsp;0) indicate that the adsorption process of MB by the composite hydrogel is a spontaneous exothermic reaction, accompanied by a decrease in system entropy. Cyclic adsorption performance testing revealed that after 10 cycles, the R value for MB adsorption by the composite hydrogel remained around 92.33%, demonstrating promising application potential in dye wastewater treatment.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003ch2\u003eDeclaration of competing interest\u003c/h2\u003e \u003cp\u003eThe authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003e**Ayiguzaili Abudiwayiti:** Investigation, Data curation, Writing-original draft. **Amatjan Sawu** t: Conceptualization, Supervision, Writing-review \u0026amp;amp; editing, Funding acquisition, Project administration. **Rena Simayi** : Conceptualization, Writing-review \u0026amp;amp; editing. **Long Cheng** : Investigation.\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e \u003cp\u003eThis study is financially supported by This study was financially supported by Natural Science Foundation of Xinjiang Uygur Autonomous Region (No. 2022D01C22). We sincerely appreciate the support.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eData will be made available on request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eFranciski MA, Peres EC, Godinho M et al (2018) Development of CO2 activated biochar from solid wastes of a beer industry and its application for methylene blue adsorption. Waste Manag 78:630\u0026ndash;638. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.wasman.2018.06.040\u003c/span\u003e\u003cspan address=\"10.1016/j.wasman.2018.06.040\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTushar KS, Sharmeen A, Ang HM et al (2010) Equilibrium, Kinetics and Mechanism of Removal of Methylene Blue from Aqueous Solution by Adsorption onto Pine Cone Biomass of Pinus radiata. Water Air Soil Pollut 218:499\u0026ndash;515. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s11270-010-0663-y\u003c/span\u003e\u003cspan address=\"10.1007/s11270-010-0663-y\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHe T, Hua J, Chen R, Yu L (2021) Adsorption characteristics of methylene blue by a dye-degrading and extracellular polymeric substance -producing strain. J Environ Manage 288:112446. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jenvman.2021.112446\u003c/span\u003e\u003cspan address=\"10.1016/j.jenvman.2021.112446\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLi Y, Wang Y, Liu L, Tian L (2023) Non-radical-dominated catalytic degradation of methylene blue by magnetic CoMoO\u003csub\u003e4\u003c/sub\u003e/CoFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e composite peroxymonosulfate activators. J Environ Manage 325:116587. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jenvman.2022.116587\u003c/span\u003e\u003cspan address=\"10.1016/j.jenvman.2022.116587\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRepon MR, Dev B, Rahman MA et al (2024) Textile dyeing using natural mordants and dyes: a review. Environ Chem Lett 22:1473\u0026ndash;1520. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s10311-024-01716-4\u003c/span\u003e\u003cspan address=\"10.1007/s10311-024-01716-4\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGuesmi Y, Agougui H, Lafi R et al (2018) Synthesis of hydroxyapatite-sodium alginate via a co-precipitation technique for efficient adsorption of Methylene Blue dye. J Mol Liq 249:912\u0026ndash;920. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.molliq.2017.11.113\u003c/span\u003e\u003cspan address=\"10.1016/j.molliq.2017.11.113\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChen H, Zhang YJ, He PY et al (2020) Coupling of self-supporting geopolymer membrane with intercepted Cr (III) for dye wastewater treatment by hybrid photocatalysis and membrane separation. Appl Surf Sci 515:146024. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.apsusc.2020.146024\u003c/span\u003e\u003cspan address=\"10.1016/j.apsusc.2020.146024\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMishra S, Cheng L, Maiti A (2021) The utilization of agro-biomass/byproducts for effective bio-removal of dyes from dyeing wastewater: A comprehensive review. J Environ Chem Eng 9:104901. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jece.2020.104901\u003c/span\u003e\u003cspan address=\"10.1016/j.jece.2020.104901\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eShiming X, Qiang L, Dongxu J et al (2020) Experimental investigation on dye wastewater treatment with reverse electrodialysis reactor powered by salinity gradient energy. Desalination 495:114541. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.desal.2020.114541\u003c/span\u003e\u003cspan address=\"10.1016/j.desal.2020.114541\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePatra BR, Nanda S, Dalai AK, Meda V (2021) Taguchi-based process optimization for activation of agro-food waste biochar and performance test for dye adsorption. Chemosphere 285:131531. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.chemosphere.2021.131531\u003c/span\u003e\u003cspan address=\"10.1016/j.chemosphere.2021.131531\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChen H, Zhou Y, Wang J et al (2020) Polydopamine modified cyclodextrin polymer as efficient adsorbent for removing cationic dyes and Cu\u003csup\u003e2+\u003c/sup\u003e. J Hazard Mater 389:121897. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jhazmat.2019.121897\u003c/span\u003e\u003cspan address=\"10.1016/j.jhazmat.2019.121897\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSafarzadeh H, Peighambardoust SJ, Mousavi SH et al (2022) Adsorption ability evaluation of the poly (methacrylic acid-co-acrylamide)/cloisite 30B nanocomposite hydrogel as a new adsorbent for cationic dye removal. Environ Res 212:113349. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.envres.2022.113349\u003c/span\u003e\u003cspan address=\"10.1016/j.envres.2022.113349\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBen Moshe S, Furman A (2022) Real-time monitoring of organic contaminant adsorption in activated carbon filters using spectral induced polarization. Water Res 212:118103. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.watres.2022.118103\u003c/span\u003e\u003cspan address=\"10.1016/j.watres.2022.118103\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYuan Y, Zhang Q, Lin S, Li J (2025) Water: The soul of hydrogels. Prog Mater Sci 148:101378. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.pmatsci.2024.101378\u003c/span\u003e\u003cspan address=\"10.1016/j.pmatsci.2024.101378\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eOviedo LR, Oviedo VR, Nora LDD et al (2023) Adsorption of organic dyes onto nano-zeolites: A machine learning study. Sep Purif Technol 315:123712. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.seppur.2023.123712\u003c/span\u003e\u003cspan address=\"10.1016/j.seppur.2023.123712\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRadoor S, Karayil J, Jayakumar A et al (2024) Recent advances in cellulose- and alginate-based hydrogels for water and wastewater treatment: A review. Carbohydr Polym 323:121339. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.carbpol.2023.121339\u003c/span\u003e\u003cspan address=\"10.1016/j.carbpol.2023.121339\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZou X, Liu H, Hu Z et al (2025) Rational design of antifreeze and flexible chitosan-based hydrogels for integration device of supercapacitors electrodes and wearable strain sensors. Carbohydr Polym 354:123342. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.carbpol.2025.123342\u003c/span\u003e\u003cspan address=\"10.1016/j.carbpol.2025.123342\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eShalla AH, Bhat MA, Yaseen Z (2018) Hydrogels for removal of recalcitrant organic dyes: A conceptual overview. J Environ Chem Eng 6:5938\u0026ndash;5949. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jece.2018.08.063\u003c/span\u003e\u003cspan address=\"10.1016/j.jece.2018.08.063\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGuo Y, Guo R, Shi X et al (2022) Synthesis of cellulose-based superabsorbent hydrogel with high salt tolerance for soil conditioning. Int J Biol Macromol 209:1169\u0026ndash;1178. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.ijbiomac.2022.04.039\u003c/span\u003e\u003cspan address=\"10.1016/j.ijbiomac.2022.04.039\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLiu Q, Zhou Y, Lu J, Zhou Y (2020) Novel cyclodextrin-based adsorbents for removing pollutants from wastewater: A critical review. Chemosphere 241:125043. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.chemosphere.2019.125043\u003c/span\u003e\u003cspan address=\"10.1016/j.chemosphere.2019.125043\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMorin-Crini N, Crini G (2013) Environmental applications of water-insoluble β-cyclodextrin\u0026ndash;epichlorohydrin polymers. Prog Polym Sci 38:344\u0026ndash;368. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.progpolymsci.2012.06.005\u003c/span\u003e\u003cspan address=\"10.1016/j.progpolymsci.2012.06.005\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAlsbaiee A, Smith BJ, Xiao L et al (2016) Rapid removal of organic micropollutants from water by a porous β-cyclodextrin polymer. Nature 529:190\u0026ndash;194. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1038/nature16185\u003c/span\u003e\u003cspan address=\"10.1038/nature16185\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNkinahamira F, Alsbaiee A, Zeng Q et al (2020) Selective and fast recovery of rare earth elements from industrial wastewater by porous β-cyclodextrin and magnetic β-cyclodextrin polymers. Water Res 181:115857. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.watres.2020.115857\u003c/span\u003e\u003cspan address=\"10.1016/j.watres.2020.115857\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eXiao Z, Xu Z, Zhou L et al (2025) Application of cyclodextrin-based microcapsules in food flavors and fragrances. Carbohydr Polym 367:123963. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.carbpol.2025.123963\u003c/span\u003e\u003cspan address=\"10.1016/j.carbpol.2025.123963\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhao J, Zou Z, Ren R et al (2018) Chitosan adsorbent reinforced with citric acid modified β-cyclodextrin for highly efficient removal of dyes from reactive dyeing effluents. Eur Polymer J 108:212\u0026ndash;218. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.eurpolymj.2018.08.044\u003c/span\u003e\u003cspan address=\"10.1016/j.eurpolymj.2018.08.044\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZheng M, Lian F, Zhu Y et al (2019) pH-responsive poly (xanthan gum-g-acrylamide-g-acrylic acid) hydrogel: Preparation, characterization, and application. Carbohydr Polym 210:38\u0026ndash;46. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.carbpol.2019.01.052\u003c/span\u003e\u003cspan address=\"10.1016/j.carbpol.2019.01.052\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhao D, Zhao L, Zhu C et al (2009) Synthesis and properties of water-insoluble β-cyclodextrin polymer crosslinked by citric acid with PEG-400 as modifier. Carbohydr Polym 78:125\u0026ndash;130. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.carbpol.2009.04.022\u003c/span\u003e\u003cspan address=\"10.1016/j.carbpol.2009.04.022\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHafiz Rozaini MN, Saad B, Lim JW et al (2022) Competitive removal mechanism to simultaneously incarcerate bisphenol A, triclosan and 4-tert-octylphenol within beta-cyclodextrin crosslinked citric acid used for encapsulation in polypropylene membrane protected-micro-solid-phase extraction. Chemosphere 309:136626. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.chemosphere.2022.136626\u003c/span\u003e\u003cspan address=\"10.1016/j.chemosphere.2022.136626\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHafiz Rozaini MN, Saad B, Lim JW et al (2022) Development of β-cyclodextrin crosslinked citric acid encapsulated in polypropylene membrane protected-\u0026micro;-solid-phase extraction device for enhancing the separation and preconcentration of endocrine disruptor compounds. Chemosphere 303:135075. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.chemosphere.2022.135075\u003c/span\u003e\u003cspan address=\"10.1016/j.chemosphere.2022.135075\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMondal S, Baghel K, Cho S et al (2025) Efficient removal of amine-modified polystyrene nano-plastics utilizing poly(N-isopropylacrylamide)-sodium carboxymethyl cellulose hydrogel beads: Parametric optimization and mechanistic insights. Sep Purif Technol 363:132035. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.seppur.2025.132035\u003c/span\u003e\u003cspan address=\"10.1016/j.seppur.2025.132035\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang W, Wang J, Zhao Y et al (2020) High-performance two-dimensional montmorillonite supported-poly (acrylamide-co-acrylic acid) hydrogel for dye removal. Environ Pollut 257:113574. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.envpol.2019.113574\u003c/span\u003e\u003cspan address=\"10.1016/j.envpol.2019.113574\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLiang Y, Hou D, Ni Z et al (2022) Preparation, characterization of naringenin, β-cyclodextrin and carbon quantum dot antioxidant nanocomposites. Food Chem 375:131646. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.foodchem.2021.131646\u003c/span\u003e\u003cspan address=\"10.1016/j.foodchem.2021.131646\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHuang W, Hu Y, Li Y et al (2018) Citric acid-crosslinked β-cyclodextrin for simultaneous removal of bisphenol A, methylene blue and copper: The roles of cavity and surface functional groups. J Taiwan Inst Chem Eng 82:189\u0026ndash;197. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jtice.2017.11.021\u003c/span\u003e\u003cspan address=\"10.1016/j.jtice.2017.11.021\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhao F, Repo E, Yin D et al (2015) EDTA-Cross-Linked β-Cyclodextrin: An Environmentally Friendly Bifunctional Adsorbent for Simultaneous Adsorption of Metals and Cationic Dyes. Environ Sci Technol 49:10570\u0026ndash;10580. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1021/acs.est.5b02227\u003c/span\u003e\u003cspan address=\"10.1021/acs.est.5b02227\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhao B, Jiang H, Lin Z et al (2019) Preparation of acrylamide/acrylic acid cellulose hydrogels for the adsorption of heavy metal ions. Carbohydr Polym 224:115022. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.carbpol.2019.115022\u003c/span\u003e\u003cspan address=\"10.1016/j.carbpol.2019.115022\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang Y, Yang N, Wang D et al (2018) Poly (MAH-β-cyclodextrin-co-NIPAAm) hydrogels with drug hosting and thermo/pH-sensitive for controlled drug release. Polym Degrad Stab 147:123\u0026ndash;131. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.polymdegradstab.2017.11.023\u003c/span\u003e\u003cspan address=\"10.1016/j.polymdegradstab.2017.11.023\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSoe HMSH, Junthip J, Chamni S et al (2023) A promising synthetic citric crosslinked β-cyclodextrin derivative for antifungal drugs: Solubilization, cytotoxicity, and antifungal activity. Int J Pharm 645:123394. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.ijpharm.2023.123394\u003c/span\u003e\u003cspan address=\"10.1016/j.ijpharm.2023.123394\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGarc\u0026iacute;a-Fern\u0026aacute;ndez MJ, Tabary N, Martel B et al (2013) Poly-(cyclo)dextrins as ethoxzolamide carriers in ophthalmic solutions and in contact lenses. Carbohydr Polym 98:1343\u0026ndash;1352. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.carbpol.2013.08.003\u003c/span\u003e\u003cspan address=\"10.1016/j.carbpol.2013.08.003\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMalik NS, Ahmad M, Minhas MU (2017) Cross-linked β-cyclodextrin and carboxymethyl cellulose hydrogels for controlled drug delivery of acyclovir. PLoS ONE 12:e0172727. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e.https://doi.org/10.1371/journal.pone.0172727\u003c/span\u003e\u003cspan address=\".10.1371/journal.pone.0172727\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLi W, Liu H, Li L, Liu K, Liu J, Tang T, Jiang W (2019) Green Synthesis of Citric Acid-Crosslinked β-Cyclodextrin for Highly Efficient Removal of Uranium (VI) from Aqueous Solution. J Radioanal Nucl Chem 322:2033\u0026ndash;2042. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s10967-019-06901-2\u003c/span\u003e\u003cspan address=\"10.1007/s10967-019-06901-2\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAltayan MM, Tzoupanos N, Barjenbruch M (2023) Polymer based on beta-cyclodextrin for the removal of bisphenol A, methylene blue and lead (II): Preparation, characterization, and investigation of adsorption capacity. J Mol Liq 390:122822. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.molliq.2023.122822\u003c/span\u003e\u003cspan address=\"10.1016/j.molliq.2023.122822\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang X, Wang Y, Hou H et al (2017) Ultrasonic Method to Synthesize Glucan-g-poly (acrylic acid)/Sodium Lignosulfonate Hydrogels and Studies of Their Adsorption of Cu\u003csup\u003e2+\u003c/sup\u003e from Aqueous Solution. ACS Sustainable Chem Eng 5:6438\u0026ndash;6446. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1021/acssuschemeng.7b00332\u003c/span\u003e\u003cspan address=\"10.1021/acssuschemeng.7b00332\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eEltaweil AS, Elgarhy GS, El-Subruiti GM, Omer AM (2020) Carboxymethyl cellulose/carboxylated graphene oxide composite microbeads for efficient adsorption of cationic methylene blue dye. Int J Biol Macromol 154:307\u0026ndash;318. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.ijbiomac.2020.03.122\u003c/span\u003e\u003cspan address=\"10.1016/j.ijbiomac.2020.03.122\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhang M, Hou S, Li Y et al (2022) Swelling characterization of ionic responsive superabsorbent resin containing carboxylate sodium groups. Reactive Funct Polym 170:105144. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.reactfunctpolym.2021.105144\u003c/span\u003e\u003cspan address=\"10.1016/j.reactfunctpolym.2021.105144\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWan X, Rong Z, Zhu K, Wu Y (2022) Chitosan-based dual network composite hydrogel for efficient adsorption of methylene blue dye. Int J Biol Macromol 222:725\u0026ndash;735. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.ijbiomac.2022.09.213\u003c/span\u003e\u003cspan address=\"10.1016/j.ijbiomac.2022.09.213\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHosseini H, Zirakjou A, McClements DJ et al (2022) Removal of methylene blue from wastewater using ternary nanocomposite aerogel systems: Carboxymethyl cellulose grafted by polyacrylic acid and decorated with graphene oxide. J Hazard Mater 421:126752. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jhazmat.2021.126752\u003c/span\u003e\u003cspan address=\"10.1016/j.jhazmat.2021.126752\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhang Y, Wei H, Hua B et al (2024) Preparation and application of the thermo-/pH\u0026ndash;/ ion-sensitive semi-IPN hydrogel based on chitosan. Int J Biol Macromol 258:128968. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.ijbiomac.2023.128968\u003c/span\u003e\u003cspan address=\"10.1016/j.ijbiomac.2023.128968\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAdel M, Ahmed MA, Mohamed AA (2021) Synthesis and characterization of magnetically separable and recyclable crumbled MgFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e/reduced graphene oxide nanoparticles for removal of methylene blue dye from aqueous solutions. J Phys Chem Solids 149:109760. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jpcs.2020.109760\u003c/span\u003e\u003cspan address=\"10.1016/j.jpcs.2020.109760\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTran TH, Le AH, Pham TH et al (2020) Adsorption isotherms and kinetic modeling of methylene blue dye onto a carbonaceous hydrochar adsorbent derived from coffee husk waste. Sci Total Environ 725:138325. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.scitotenv.2020.138325\u003c/span\u003e\u003cspan address=\"10.1016/j.scitotenv.2020.138325\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhang P, O\u0026rsquo;Connor D, Wang Y et al (2020) A green biochar/iron oxide composite for methylene blue removal. J Hazard Mater 384:121286. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jhazmat.2019.121286\u003c/span\u003e\u003cspan address=\"10.1016/j.jhazmat.2019.121286\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMohamed AK, Mahmoud ME (2020) Nanoscale Pisum sativum pods biochar encapsulated starch hydrogel: A novel nano-sorbent for efficient chromium (VI) ions and naproxen drug removal. Bioresour Technol 308:123263. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.biortech.2020.123263\u003c/span\u003e\u003cspan address=\"10.1016/j.biortech.2020.123263\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAi T, Jiang X, Liu Q et al (2019) Daptomycin adsorption on magnetic ultra-fine wood-based biochars from water: Kinetics, isotherms, and mechanism studies. Bioresour Technol 273:8\u0026ndash;15. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.biortech.2018.10.039\u003c/span\u003e\u003cspan address=\"10.1016/j.biortech.2018.10.039\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSingha NR, Mahapatra M, Karmakar M et al (2017) Synthesis of guar gum-g-(acrylic acid-co-acrylamide-co-3-acrylamido propanoic acid) IPN via in situ attachment of acrylamido propanoic acid for analyzing superadsorption mechanism of Pb (II)/Cd (II)/Cu (II)/MB/MV. Polym Chem 8:6750\u0026ndash;6777. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1039/C7PY01564J\u003c/span\u003e\u003cspan address=\"10.1039/C7PY01564J\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWan X, Rong Z, Zhu K, Wu Y (2022) Chitosan-based dual network composite hydrogel for efficient adsorption of methylene blue dye. Int J Biol Macromol 222:725\u0026ndash;735. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.ijbiomac.2022.09.213\u003c/span\u003e\u003cspan address=\"10.1016/j.ijbiomac.2022.09.213\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHussain S, Salman M, Youngblood JP et al (2024) Enhanced adsorption of Congo red dye by CS/PEG/ZnO composite hydrogel: Synthesis, characterization, and performance evaluation. J Mol Liq 411:125704. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.molliq.2024.125704\u003c/span\u003e\u003cspan address=\"10.1016/j.molliq.2024.125704\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSari Yilmaz M (2022) Graphene oxide/hollow mesoporous silica composite for selective adsorption of methylene blue. Microporous Mesoporous Mater 330:111570. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.micromeso.2021.111570\u003c/span\u003e\u003cspan address=\"10.1016/j.micromeso.2021.111570\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhang Y, Wang P, Hussain Z et al (2022) Modification and characterization of hydrogel beads and its used as environmentally friendly adsorbent for the removal of reactive dyes. J Clean Prod 342:130789. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jclepro.2022.130789\u003c/span\u003e\u003cspan address=\"10.1016/j.jclepro.2022.130789\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eOvchinnikov OV, Evtukhova AV, Kondratenko TS et al (2016) Manifestation of intermolecular interactions in FTIR spectra of methylene blue molecules. Vib Spectrosc 86:181\u0026ndash;189. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.vibspec.2016.06.016\u003c/span\u003e\u003cspan address=\"10.1016/j.vibspec.2016.06.016\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePang J, Fu F, Ding Z et al (2017) Adsorption behaviors of methylene blue from aqueous solution on mesoporous birnessite. J Taiwan Inst Chem Eng 77:168\u0026ndash;176. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jtice.2017.04.041\u003c/span\u003e\u003cspan address=\"10.1016/j.jtice.2017.04.041\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eShen Y, Ni W-X, Li B (2021) Porous Organic Polymer Synthesized by Green Diazo-Coupling Reaction for Adsorptive Removal of Methylene Blue. ACS Omega 6:3202\u0026ndash;3208. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1021/acsomega.0c05634\u003c/span\u003e\u003cspan address=\"10.1021/acsomega.0c05634\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLi K, Yan J, Zhou Y et al (2021) β-cyclodextrin and magnetic graphene oxide modified porous composite hydrogel as a superabsorbent for adsorption cationic dyes: Adsorption performance, adsorption mechanism and hydrogel column process investigates. J Mol Liq 335:116291. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.molliq.2021.116291\u003c/span\u003e\u003cspan address=\"10.1016/j.molliq.2021.116291\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang W, Wang J, Zhao Y et al (2020) High-performance two-dimensional montmorillonite supported-poly (acrylamide-co-acrylic acid) hydrogel for dye removal. Environ Pollut 257:113574. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.envpol.2019.113574\u003c/span\u003e\u003cspan address=\"10.1016/j.envpol.2019.113574\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMallard I, Landy D, Fourmentin S (2020) Evaluation of polyethylene glycol crosslinked β-CD polymers for the removal of methylene blue. Appl Sci 10:4679. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3390/app10134679\u003c/span\u003e\u003cspan address=\"10.3390/app10134679\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJurado-L\u0026oacute;pez B, Vieira RS, Rabelo RB et al (2017) Formation of complexes between functionalized chitosan membranes and copper: A study by angle resolved XPS. Mater Chem Phys 185:152\u0026ndash;161. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.matchemphys.2016.10.018\u003c/span\u003e\u003cspan address=\"10.1016/j.matchemphys.2016.10.018\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChen P, Cao Z, Wen X et al (2017) A novel mesoporous silicate material (MS) preparation from dolomite and enhancing methylene blue removal by electronic induction. J Taiwan Inst Chem Eng 80:128\u0026ndash;136. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jtice.2017.08.044\u003c/span\u003e\u003cspan address=\"10.1016/j.jtice.2017.08.044\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWu H, Kong J, Yao X et al (2015) Polydopamine-assisted attachment of β-cyclodextrin on porous electrospun fibers for water purification under highly basic condition. Chem Eng J 270:101\u0026ndash;109. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.cej.2015.02.019\u003c/span\u003e\u003cspan address=\"10.1016/j.cej.2015.02.019\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhu J, Luo Y, Wang J et al (2022) Highly efficient uranium extraction by aminated lignin-based thermo-responsive hydrogels. J Mol Liq 368:120744. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.molliq.2022.120744\u003c/span\u003e\u003cspan address=\"10.1016/j.molliq.2022.120744\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"colloid-and-polymer-science","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":" Learn more about [Colloid and Polymer Science](https://www.springer.com/journal/396) ","snPcode":"396","submissionUrl":"https://mc.manuscriptcentral.com/cps","title":"Colloid and Polymer Science","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"β-cyclodextrin, hydrogel, Dye adsorption, Methylene blue, Wastewater treatment","lastPublishedDoi":"10.21203/rs.3.rs-8874053/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8874053/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eWater pollution poses a severe threat to human health and ecological systems, thereby demanding high-performance adsorbents for wastewater treatment. Herein, a novel composite hydrogel (CA-β-CD/P(AA-co-AM)) was synthesized via radical polymerization using citric acid-modified β-CD (CA-β-CD). Citric acid modification introduced functional sites, tuned cavity structure, and linked β-CD units into oligomer, overcoming native β-CD\u0026rsquo;s limitations to serve as an ideal hydrogel component. The incorporation of CA-β-CD into P(AA-co-AM) formed a porous network, enabled synergistic interactions, enhanced stability, and integrated CA-β-CD\u0026rsquo;s adsorption superiority with the polymer\u0026rsquo;s robust matrix. The structure and properties of the composite hydrogel were characterized by FT-IR, \u003csup\u003e1\u003c/sup\u003eH NMR, SEM, TGA, GPC, and XPS. It showed outstanding methylene blue (MB) adsorption via host\u0026ndash;guest inclusion, hydrogen bonding, and electrostatic interactions, with a maximum capacity of 3743.23 mg/g. Adsorption followed pseudo-second-order kinetics and Langmuir isotherm, with rate controlled by intra-particle and liquid film diffusion. Importantly, the composite hydrogel maintained excellent reusability \u0026mdash; after 10 consecutive adsorption\u0026ndash;desorption cycles, the MB removal rate (R) remained above 92%. This work provides a promising strategy for cyclodextrin-derived adsorbents in dye wastewater treatment.\u003c/p\u003e","manuscriptTitle":"Preparation of citric acid-modified β-cyclodextrin/poly (acrylic acid-co- acrylamide) composite hydrogel for enhanced methylene blue adsorption","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-03-26 07:24:35","doi":"10.21203/rs.3.rs-8874053/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-04-28T07:23:17+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-13T02:41:05+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"15292273500320641927933192800027501583","date":"2026-03-31T13:36:24+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-03-24T09:12:10+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-02-19T13:56:04+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-02-19T13:50:59+00:00","index":"","fulltext":""},{"type":"submitted","content":"Colloid and Polymer Science","date":"2026-02-13T16:22:44+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"colloid-and-polymer-science","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"","sideBox":" Learn more about [Colloid and Polymer Science](https://www.springer.com/journal/396) ","snPcode":"396","submissionUrl":"https://mc.manuscriptcentral.com/cps","title":"Colloid and Polymer Science","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"5abf2d66-38ad-407c-bb2b-5339ee00a2fc","owner":[],"postedDate":"March 26th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-05-12T16:53:12+00:00","versionOfRecord":[],"versionCreatedAt":"2026-03-26 07:24:35","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8874053","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8874053","identity":"rs-8874053","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}