Adsorption of amoxicillin by chitosan and alginate biopolymers composite beads.

Adsorption of amoxicillin by chitosan and alginate biopolymers composite beads. | 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 Adsorption of amoxicillin by chitosan and alginate biopolymers composite beads. Claudio Pereira Pinheiro, Beatriz Kaori Tokura, Natália Soares Germano, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4331760/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 28 Oct, 2024 Read the published version in Environmental Science and Pollution Research → Version 1 posted 6 You are reading this latest preprint version Abstract Amoxicillin is one of the most used antibiotics worldwide, and due to incomplete metabolism in the human body or inadequate disposal, it has been detected in the receiving water bodies. One of the major concerns is the promotion of antibiotic resistance, as well as its toxicity to aquatic organisms such as fish, invertebrates, and algae, and its ability to disrupt the natural microbial communities in water bodies. Moreover, water and wastewater treatment plants struggle to effectively treat water contaminated with amoxicillin. Consequently, new processes need to be explored to complement traditional water and wastewater treatments. Adsorption, being a relatively economical and simple technique, appears promising for this purpose. Numerous adsorbents are found in the literature to adsorb drugs, however, the fabrication of all these adsorbents involves various complex steps and substances when compared to the chitosan and alginate beads. Therefore, the objective of this study was to assess the adsorption of amoxicillin on chitosan and alginate beads. The optimal pH was found to be 4 for both beads. The kinetics study indicates that external diffusion governs adsorption for alginate, while internal diffusion governs adsorption for chitosan. Thermodynamic parameters demonstrated that adsorption is a spontaneous and endothermic process. wastewater renewable Thermodynamic kinetics external diffusion internal diffusion Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 1. Introduction Antibiotics such as amoxicillin are substances capable of eliminating or inhibiting the multiplication of bacteria (Donnelly et al. 2024 ). Amoxicillin belongs to the penicillin class, being one of the most prescribed medications in the United States, with over 25 million prescriptions in 2022 alone (Cohen et al. 2023 ). Amoxicillin continues with an exponential increase in prescriptions worldwide (Georgin et al. 2020). However, the substance is excreted in the urine within the first hours without structure alteration. The estimated percentage of the administered amoxicillin dose excreted in the urine without undergoing structural alterations ranges between 60–80% (Ding et al. 2023 ). Consequently, amoxicillin is one of the most commonly found antibiotics in wastewater (Al-Saidi et al. 2023 ). Some studies have reported the presence of amoxicillin in concentrations ranging from ng L − 1 to mg L − 1 in domestic wastewater in several world regions (Andreozzi et al. 2004 ; Watkinson et al. 2007 ; Zuccato et al. 2010 ; Patel et al. 2019 ). The occurrence of amoxicillin in wastewater poses a potential risk due to its direct biological action on microorganisms, leading to the development of resistant bacteria that can be transmitted from animals to humans, as amoxicillin has trophic magnification capability (Gupta et al. 2023 ). A significant issue with amoxicillin is that it may pass through wastewater treatment plants intact and might not be detected by conventional methods due to its low concentration. Therefore, it is necessary to study techniques that complement traditional water and wastewater treatments. Adsorption, involving the transfer of a substance from a fluid phase (adsorbate) to a solid phase (adsorbent), proves to be a promising technique. The advantages of adsorption include its relatively low cost, high efficiency, operational ease, possible regeneration of the adsorbent, and versatility in eliminating various pharmaceuticals, regardless of their specific chemical properties (Moro et al. 2017 ). It is widely accepted that standard liquid/solid adsorption involves film diffusion, intraparticle diffusion, and mass action. In the case of physical adsorption, mass action is a rapid process and may be inconsequential for kinetic studies. Consequently, the kinetic aspect of adsorption is typically governed by either liquid film diffusion or intraparticle diffusion, with one of these processes serving as the rate-limiting step. Adsorption is adjustable to different operational conditions, such as pH, temperature, and drug concentration. The pH of the medium influences the charge of the adsorbent and adsorbate, providing a straightforward way to control the adsorptive properties. Thus, it is possible to conduct adsorption and desorption through pH or ionic strength variations (Pinheiro et al. 2021 ). Furthermore, while a variety of adsorbents can be utilized, biopolymers emerge as particularly noteworthy when environmental considerations are taken into account. In this context, natural polymers, such as chitosan and alginate, have been explored as potential green adsorbents for wastewater treatment for adsorption of different contaminants, such as dyes (Sadiq et al. 2021 ; Rocher et al. 2008 ) and metal ions (Gerente et al. 2007 ; Gao et al. 2020 ). Chitosan is obtained from chitin through a deacetylation reaction process in alkaline medium, resulting in a molecular structure closely resembling that of chitin (Benettayeb et al. 2023 ) However, chitosan has a higher number of free amino groups in its polymeric chain, allowing its use as a biomaterial in microparticle, gel, and membrane shapes. Typically, chitosan has a positive surface charge at pH values below 6 (Vedula and Yadav, 2023 ). Alginate, on the other hand, is a polysaccharide extracted from brown seaweeds, specifically Phaeophyta . One of its characteristics is its selective binding ability with multivalent cations, especially calcium ions, which is a prerequisite for its gel-forming capacity (Berg and Seiffert, 2023 ). Normally, the pK a of alginate is in the range of 3.3 to 3.7 for the carboxylic groups present in its structure. Therefore, alginate should exhibit a positive charge at pH below 3 and a negative charge above it, due to the carboxyl groups present in its structure. Amoxicillin displays amphoteric properties due to its various functional groups: carboxylic ( pK a1 = 2.7), amino ( pK a2 = 7.5), and phenolic hydroxyl ( pK a3 = 9.6) (De Marco et al., 2017 ).). So, the isoelectric point ( pI ) of amoxicillin can vary depending on specific conditions. However, typically, the pI of amoxicillin falls within the pH range of its two pK a values, which are around 2.7 and 7.5. Typically, amoxicillin exhibits a cationic characteristic at pH values below 2.7 (Adriano et al., 2005 ). Several adsorbents have been utilized for drug adsorption; however, many are challenging to synthesize. Hence, the use of chitosan and alginate beads emerges as promising alternatives, given their relatively simple synthesis process. Therefore, it is necessary to study the interaction between chitosan and alginate beads adsorbents with amoxicillin at different pH levels, and subsequently, the influence of temperature, as the kinetic aspect of adsorption is governed by either liquid film diffusion or intraparticle diffusion. 2. Material and methods 2.1 Material Chitosan ≥ 75% deacetylated from shrimp shells and alginic acid sodium salt from brown algae were acquired from Sigma-Aldrich (USA). Amoxicillin was purchased commercially; each capsule contains 574 mg of tri-hydrated amoxicillin. Other chemicals were of analytical grade. 2.2 Chitosan and alginate solution preparation Chitosan was dissolved in a 1% acetic acid solution (v v − 1 ) at a ratio of 1 g per 50 mL, while alginate was dissolved in ultrapure water at a ratio of 1 g per 50 mL. Both solutions were maintained under constant agitation and at a consistent temperature. 2.3 Preparation of the beads The Fig. 1 presents the general flowchart of the study. The beads were formed using dripping techniques, with a burette positioned 4 cm away from the appropriate coagulating solution. For chitosan, a 1 mol/L NaOH solution was employed, and for alginate, a 20% CaCl 2 solution was utilized as coagulation solution. Subsequently, the beads were allowed to rest for 48 hours before undergoing a washing process until a neutral pH was achieved. Finally, they were filtered (Pinheiro et al. 2021 ). The mean diameter was measured using a micrometer. 2.4 Scanning electron microscopy ( SEM ) Morphological characterization was conducted using scanning electron microscopy (SEM). The SEM JSM-6610LV (JEOL, Japan) was employed, operating at an acceleration voltage of 10 kV and a current of 50 mA. Prior to SEM analysis, the samples underwent gold coating. 2.5 Thermogravimetry ( TGA ) and differential scanning calorimetry ( DSC ) TGA analyses were conducted using the DTG-60H analyzer, while differential scanning calorimetry (DSC) analyses were performed with the DSC-60 analyzer, both from Shimadzu (Japan). For TGA, the temperature range employed was 25 to 600°C, with a heating rate of 10°C min⁻¹ and a nitrogen flow rate of 50 mL min⁻¹. DSC experiments involved heating from room temperature to 150 ºC, followed by cooling to 10 ºC through a cooling ramp, and subsequent heating to 250 ºC, at a heating rate of 10°C min⁻¹ under a nitrogen atmosphere. 2.6 Adsorption The concentration of the amoxicillin solution was determined through a standard curve using a spectrophotometer at a wavelength of 279 nm. A Revolver-type tube rotator (Thermo Scientific, USA) was used to provide end-over-end agitation. The determination of the optimum pH was conducted employing 1 g of adsorbent and a concentration of 300 mg L − 1 of amoxicillin, while maintaining constant temperature and agitation rate. The pH of each solution was adjusted using different proportions of disodium phosphate and citric acid (Mcllvaine buffer). After identifying the optimal pH, the kinetics study was conducted under the same conditions. Adsorption isotherms were performed at three different temperatures (5°C, 20°C, and 35°C), varying the concentration of amoxicillin from 50 to 300 mg L − 1 , under the same conditions mentioned earlier. The adsorption capacity was calculated by Eq. 1 . $${q}_{e}=\frac{\left({C}_{0}-{C}_{e}\right)}{m}V$$ 1 where q e is adsorbed amount (mg g − 1 ), C 0 and C e are the initial and equilibrium amoxicillin concentrations in the liquid phase (mg L − 1 ), respectively; m is the adsorbent mass (g) and V is the volume of the solution (L), 2.7 Kinetics and adsorption isotherm models In the kinetics study, the adsorption process is consistently influenced by either liquid film diffusion or intraparticle diffusion, where one of these mechanisms serves as the rate-limiting step. Consequently, two models were applied to the data: an external diffusion model (Boyd's external diffusion, Eq. 4) and an internal diffusion model (Weber and Morris, Eq. 5 ). q t = q ∞ (1- e − Rt ) (4) $${q}_{t}={k}_{\text{W}\&\text{M}}{t}^{1/2}$$ 5 where q ∞ is the equilibrium adsorption capacity at infinite time (mg g − 1 ), t is the adsorption time (h), R is the rate coefficient (h − 1 ) and \({k}_{\text{W}\&\text{M}}\) is the intraparticle diffusion coefficient (mg g − 1 h − 1/2 ) In the study of adsorption isotherms, Langmuir (Eq. 6 ) and Freundlich (Eq. 7 ) parameters were fitted to the experimental data. $${q}_{e}=\frac{{q}_{m}{{K}_{d}C}_{e}}{1+{{K}_{d}C}_{e}}$$ 6 $${q}_{e}={K}_{f}{C}_{e}^{1/n}$$ 7 q m is the maximum adsorption capacity in the monolayer (mg g − 1 ) and k d is the Langmuir constant (L mg − 1 ), K f (mol L − 1 ) is the Freundlich constant, and n is the heterogeneity factor. 2.8 Thermodynamic parameters As per Pinheiro et al. ( 2019 ), the change in Gibbs free energy (kJ mol − 1 ) was computed utilizing Eq. 2 , and the enthalpy and entropy parameters were ascertained through the Van't Hoff graph, as outlined in Eq. 3 . $$\varDelta {G}^{^\circ }=-RTln\left({\rho }_{{H}_{2}O}{K}_{\text{d}}\right)$$ 2 $$ln{K}_{D}=\frac{-\varDelta H}{RT}+\frac{\varDelta S}{R}$$ 3 where \(\varDelta {G}^{^\circ }\) is the variation in Gibbs free energy (kJ mol − 1 ), R is the universal gas constant (0.008314 kJ mol − 1 K − 1 ), T is the absolute temperature (K), and \({\rho }_{{H}_{2}O}\) is the specific weight of water (mg L − 1 ), Δ H is the enthalpy (kJ mol − 1 ) and Δ S is the entropy (kJ mol − 1 K − 1 ) and K d represents the thermodynamic equilibrium constant of the Langmuir model (L mg − 1 ). 2.9 Statistical treatment Nonlinear regression analysis was employed to fit the models to the experimental data, as described by Vieira et al. ( 2019 ). The calculations were carried out using the Origin® software from Microcal, based in the United States, and employing the iterative Levenberg-Marquardt method. To assess the quality of the fit, the coefficient of determination ( R ²) and the Pearson chi-square test (χ²) were used (Eq. 8 ), following the methodology of El-Khaiary and Malash ( 2011 ). The generation of corresponding graphs were performed in the same software. All experiments were conducted in triplicate. $${\chi }^{2}=\sum \frac{{\left({q}_{exp}-{q}_{cal}\right)}^{2}}{{q}_{exp}^{2}}$$ 8 where \({q}_{exp}\) is the experimental adsorption capacity (mg L − 1 ) and \({q}_{cal}\) is the calculated adsorption capacity (mg L − 1 ) 3. Results and discussion 3.1 Characterization of the microparticles Examining the scanning electron microscopy images (Fig. 2 a and 2 b), one can discern that both beads display a spherical shape. Nevertheless, the surface of chitosan exhibits higher roughness and porosity compared to alginate. This feature is likely to have played an important role in enabling chitosan to attain a higher adsorbed amount than alginate across all adsorption experiments. The mean diameter measured for the wet beads was 1.89 ± 0.02 mm for chitosan and 1.98 ± 0.02 mm for alginate. After drying in a forced-air oven at 25°C for 24 hours, the diameters were 1.11 ± 0.02 mm for alginate (loss of 43.94 ± 0,08%) and 0.98 ± 0.02 mm for chitosan (loss of 48.15 ± 0,07%). Therefore, chitosan experienced a greater water loss than alginate. This difference is likely attributed to the presence of amino groups in chitosan, along with its evidently higher porosity (Fig. 2 ). Adriano et al. ( 2005 ) produced chitosan beads crosslinked with 5% glutaraldehyde, featuring an average diameter of 2.12 mm (wet basis). Therefore, not only do the beads of pure chitosan have their active sites unobstructed by crosslinking, but their volume is also smaller. The TGA assesses the mass variation of the sample with respect to temperature. Figure 3 a shows the thermogram of alginate beads, which shows that the evaporation of water molecules occurs within the temperature range of 25°C to 200°C. This investigation reveals a substantial mass reduction initiating at 200°C and extending to 320°C, encompassing the dehydration of saccharide rings and the rupture of C–O–C bonds. The ultimate decomposition temperatures are observed at 500°C and 600°C, signaling a virtual cessation of mass loss (Adzmi et al. 2012 ; Estrada-Villegas et al. 2020 ). Figure 3 b illustrates the thermogram of chitosan beads, in which the initial weight loss phase is evident within the temperature range of 25°C to 120°C, attributed to moisture loss (approximately 10%). Chitosan experiences non-oxidative thermal degradation under nitrogen flow, observed in the temperature span of 245°C to 600°C. This indicates the deacetylation of chitosan, involving vaporization and elimination of volatile products. The degradation process of chitosan starts with amino groups forming unsaturated structures (Dey et al. 2016 ). The DSC thermogram of alginate beads (Fig. 4 a) reveals two distinct endothermic peaks at 100°C and 200°C. The first is likely attributed to water evaporation, while the second indicates a melting point. The introduction of amoxicillin into the alginate beads significantly reduces the intensity of these peaks. For the peak at 100°C, amoxicillin occupies the space previously filled by water (Patel et al., 2006 ; Venkateswarlu, 2017 ). Additionally, amoxicillin demonstrates an affinity for binding with water molecules. The second peak (200°C) is associated with the interaction between alginate and amoxicillin, as both possess various functional groups (Bankole et al., 2022 ). This observation implies the molecular dispersion of drugs within the beads. The primary distinction in Fig. 4 a is the peak observed around 140°C in the DSC thermogram of alginate and amoxicillin; however, this peak is not present in the thermogram of alginate alone. The endothermic peak around 140°C indicates a thermal transition in amoxicillin, potentially associated with its phase changes (Newton et al., 2014 ). This peak is also evident in Fig. 4 b (DSC thermogram of chitosan beads containing amoxicillin), contrasting with its absence in the chitosan-only thermogram. The DSC thermogram (Fig. 4 b) of chitosan beads suggests that the initial peak corresponds to the evaporation of free water. However, chitosan exhibits a strong affinity for water, resulting in a large peak that follow the temperature increase. The presence of amoxicillin leads to the merging of the peak associated with water loss with the peak of thermal transition in amoxicillin, potentially connected to its phase changes, as observed in the thermogram of Fig. 4 a (Maswadeh, 2017 ). This occurs due to amoxicillin's strong affinity for water (Narkar et al. 2010 ). 3.2 Effect of pH In Table 1 , it can be observed that the optimal pH for the adsorption of amoxicillin onto beads of chitosan and alginate was pH 4. As per Adriano et al. ( 2005 ), amoxicillin exhibits an isoelectric point of 5.7. This distinctive feature is ascribed to the functional groups inherent in amoxicillin, namely, carboxyl (with a pK a1 of 2.68), amine (with a pK a2 of 7.49), and phenolic hydroxyl (with a pK a3 of 9.63). At the pH equal to pK a3 , the phenolic hydroxyl group undergoes deprotonation, resulting in amoxicillin carrying a double negative charge. When the pH falls within the range of pK a2 and pK a3 values, deprotonation of the amine group takes place. At a pH value between pK a1 and pK a2 , amoxicillin remains uncharged due to the deprotonation of the carboxylic group. Lastly, amoxicillin demonstrates a cationic characteristic at pH values lower than 2.68 (Barbooti and Zahraw, 2020 ). Table 1 Effect of pH variation on the amoxicillin adsorption capacity. Alginate Chitosan pH mg g − 1 mg g − 1 3 58.4 \(\pm\) 0.2 55.4 \(\pm\) 0.3 4 74.2 \(\pm\) 0.3 80.4 \(\pm\) 0.2 5 55.4 \(\pm\) 0.2 62.4 \(\pm\) 0.2 6 30.6 \(\pm\) 0.1 42.3 \(\pm\) 0.1 7 - 33.2 \(\pm\) 0.2 8 - 20.4 \(\pm\) 0.3 Mean \(\pm\) standard deviation (n = 3) Concerning chitosan, the positive surface charge of chitosan tends to increase with a decrease in pH, below pH 6 (Camara et al. 2020). This phenomenon arises from the protonation of the amino group. In contrast, the surface charge of amoxicillin tends to remain neutral between pH 2.7 and 7.5. Therefore, at pH below 4, there is an increase in the repulsion between amoxicillin and chitosan, because amoxicillin contains an amino group that tends to be protonated with a decrease in pH. With an increase in pH, deprotonation of chitosan occurs, resulting in a diminished attraction between chitosan and amoxicillin. Alginate exhibits a negative charge with an increase in pH above 3, due to the presence of the carboxylic group. The presence of the carboxylic group in alginate and the amino group in amoxicillin are likely responsible for the interaction and, consequently, adsorption, with a maximum interaction at pH 4. Adsorption above pH 6 was not feasible because alginate beads dissolved in water (Gao et al. 2020 ). In the literature, amoxicillin adsorption has been investigated using various adsorbents, and the maximum adsorption capacity observed by fitting the Langmuir model varies widely: it ranges from 2.28 mg g⁻¹ for Organobentonite (Xing Zha et al. 2013 ) to 909 mg g⁻¹ for magnetic Bionanocomposite (Mosavi et al. 2023 ). Other reported values include 7.3 mg g⁻¹ using methylene blue (Barbooti and Zahraw, 2020 ), 135 mg g⁻¹ at 30°C for activated carbon prepared from durian shell (Yazidi et al. 2020 ), 345.4 mg g⁻¹ for activated carbon from Arundodonax biomass (Chayid and Ahmed, 2015 ), 357 mg g⁻¹ at pH 9 for tecomachip wood waste into microwave-irradiated adsorbent (Khan et al. 2023 ), and 526 mg g⁻¹ for Graphene/copper oxide nanocomposites (Moradi et al. 2022 ). However, the fabrication of all these adsorbents involves numerous intricate steps and a variety of chemical reagents, making the process considerably more complex when compared to the relatively simpler production of chitosan and alginate beads. Additionally, these more complex fabrication methods may have potential ecological impacts, such as increased chemical waste generation and energy consumption. 3.3 Effect of contact time Figure 5 shows the adsorption kinetics of amoxicillin in alginate and chitosan beads, as well as the fitting of data to the Boyd and Weber and Morris models. Chitosan took 200 minutes to reach an adsorption capacity of 78.6 mg g⁻¹, while alginate took 250 minutes to reach 71.3 mg g⁻¹. When adsorption is physical, the influence of mass action may be neglected. As will be demonstrated, the enthalpy obtained in this study is characteristic of physical adsorption. Therefore, adsorption is governed by either liquid film diffusion or intraparticle diffusion. Both mechanisms are often present simultaneously in many heterogeneous systems, and the overall rate of mass transfer is usually determined by the slowest step, which may vary depending on the specific conditions of the system. Experimental techniques, such as fitting experimental data to mathematical models like the Weber-Morris equation, can help elucidate the relative contributions of liquid film diffusion and intraparticle diffusion to the overall mass transfer process. Liquid film diffusion refers to the process of mass transfer that occurs as a solute in a fluid phase moves from the bulk of the fluid to the surface of a solid particle, where adsorption or reaction takes place. Intraparticle diffusion, on the other hand, occurs within the solid particles themselves. After reaching the surface of the solid, the solute must then diffuse into the pores or internal structure of the solid particle. According to Table 2 , the best-fitted model for chitosan was Boyd's external diffusion, indicating that the rate-limiting step is the external diffusion model. However, for alginate, a better fit was obtained with the Weber and Morris model, thus indicating that the rate-limiting step is the internal diffusion model. Intraparticle diffusion can be influenced by pore size, and as observed in Fig. 2 , the surface of chitosan exhibits higher roughness and porosity compared to alginate, which may facilitate the internal mass transfer in chitosan beads. This difference in beads morphology may explain the results regarding the rate-limiting step for adsorption observed in chitosan and alginate beads. Table 2 Parameters for the study of amoxicillin kinetics. Chitosan Alginate Chitosan Alginate Boyd's external diffusion Weber and Morris \({\chi }^{2}\) 74 \(\pm\) 1.2 82 \(\pm\) 1.1 142 \(\pm\) 1.8 0.961 \(\pm\) 0.001 R 2 0.973 \(\pm\) 0.001 0.961 \(\pm\) 0.001 0.991 \(\pm\) 0.001 0.933 \(\pm\) 0.001 \({k}_{\text{W}\&\text{M}}\) - - 4.13 + 0.11 5.51 + 0.057 q ∞ 82.72 \(\pm\) 3.12 136.75 \(\pm\) 8.2 - - R 0.0125 \(\pm\) 0.0014 0.00251 \(\pm\) 0.0012 - - Mean \(\pm\) standard deviation (n = 3) 3.4 Effect of temperature Observing Fig. 6 , it is evident that the increase in temperature resulted in an enhancement of the adsorption capacity. This is because amoxicillin may experience solvent solvation effects, and thus, at higher temperatures, amoxicillin has more energy to overcome solvation. Analyzing the results presented in Table 3 , it is noticeable that the best-fitted model for chitosan beads was the Freundlich model. Furthermore, the Freundlich constant n was greater than 1 in all cases, indicating that the surface of chitosan is non-homogeneous, contrary to what the Langmuir model suggests (Perwitasari et al. 2021 ). This suggests that one adsorption site might interfere with adsorption at another site. Regarding alginate beads, generally, the Freundlich model also provided a better fit. The behavior of n for alginate beads was similar to that observed for chitosan beads. That is, the adsorption of one molecule favors the adsorption of another molecule, indicating positive cooperativity. Table 3 Equilibrium isotherm parameters for amoxicillin adsorption. Chitosan Alginate Langmuir T q m K d R 2 q m K d R 2 278 98.4 \(\pm\) 0.8 0.0348 \(\pm\) 0.0002 0.857 \(\pm\) 0.001 60.8 \(\pm\) 1.2 0.0191 \(\pm\) 0.0002 0.859 \(\pm\) 0.001 293 102.2 \(\pm 0.9\) 0.057 \(\pm\) 0.0002 0.981 \(\pm\) 0.001 104.3 \(\pm\) 0.8 0.0209 \(\pm\) 0.0002 0.981 \(\pm\) 0.001 308 94.4 \(\pm 0.7\) 0.083 \(\pm\) 0.0002 0.984 \(\pm\) 0.001 99.0 \(\pm\) 0.7 0.0344 \(\pm\) 0.0002 0.994 \(\pm\) 0.001 Freundlich 278 2.7 \(\pm 0.4\) 1.7 \(\pm\) 0.1 0.992 \(\pm\) 0.001 0.7 \(\pm\) 0.4 1.6 \(\pm\) 0.2 0.996 \(\pm\) 0.001 293 15.1 \(\pm 0.5\) 2.9 \(\pm 0.2\) 0.991 \(\pm\) 0.001 10.8 \(\pm\) 0.4 2.5 \(\pm\) 0.2 0.991 \(\pm\) 0.001 308 11.3 \(\pm 0.7\) 2.7 \(\pm\) 0.1 0.996 \(\pm\) 0.001 7.1 \(\pm\) 0.5 2.2 \(\pm\) 0.2 0.990 \(\pm\) 0.001 Mean \(\pm\) standard deviation (n = 3) Adriano et al. ( 2005 ) investigated the adsorption of amoxicillin on chitosan beads crosslinked with 5% glutaraldehyde at pH 6.5. They achieved a maximum adsorption capacity of only 8.71 mg g − 1 , according to the Langmuir model. This diminished capacity is likely attributable to the glutaraldehyde, which reduces the number of active sites on the chitosan available for adsorption. Furthermore, in this study, a significantly higher maximum adsorption capacity of 102 mg g − 1 was observed, according to the Langmuir model. This disparity underscores how glutaraldehyde not only hampers drug adsorption but also complicates the synthesis of chitosan beads by introducing additional steps. Mirizadeh et al. ( 2024 ) investigated the removal of amoxicillin by magnetic chitosan/microalgae biocomposites, achieving optimal results between pH 5 and 6, obtaining a maximum adsorption capacity of 125.6 mg g − 1 . Yeo et al. ( 2023 ) investigated the adsorption of amoxicillin using a bentonite-chitosan composite and observed a maximum capacity of 66 mg g − 1 at 50°C. Danalioğlu et al. ( 2017 ) adsorbed amoxicillin using magnetic activated carbon/chitosan and achieved an adsorption capacity of 98 mg g − 1 for 15 mg of adsorbent; however, the pH of the medium was not controlled. Our adsorption capacity was similar to those reported in the literature; however, it is noteworthy that the adsorption sites on chitosan beads are more accessible compared to the mentioned adsorbents in the literature. This is because the beads did not undergo any crosslinking process, nor did the amino groups form chemical bonds with other compounds. Abed and Faisal ( 2023 ) explored the adsorption of amoxicillin using a calcium/iron-layered double hydroxides-sodium alginate nanoadsorbent at pH 7, achieving a maximum capacity of 6.7 mg g − 1 according to the Langmuir model. Kaur and Maity ( 2020 ) successfully removed amoxicillin using a graphene oxide/calcium alginate biocomposite, achieving a maximum adsorption capacity of 50 mg g − 1 at pH 6. In their study, Karimi and Namazi ( 2022 ) effectively adsorbed amoxicillin utilizing alginate/glycodendrimer beads, achieving a maximum adsorption capacity of 48.8 mg g − 1 at pH 7. Alhattab et al. ( 2023 ), using alginate/bentonite-impregnated TiO 2 beads for amoxicillin adsorption, achieved an adsorption capacity of 85 mg g − 1 at pH 6. The adsorption capacity achieved in this study for the alginate beads was 74.2 ± 0.3 mg g − 1 at pH 4, higher than several previously cited adsorption capacities. Additionally, the manufacture of these aforementioned adsorbents involves numerous intricate steps and the use of various chemical reagents, significantly complicating the process compared to the relatively straightforward production of alginate beads. Furthermore, these more complex fabrication methods could potentially result in ecological ramifications, such as increased generation of chemical waste and energy consumption. 3.5 Thermodynamic parameters Table 4 reveals that the change in Gibbs free energy (Δ G ) was consistently negative for both beads at all temperatures, indicating a spontaneous process. The rise in temperature further enhanced adsorption, leading to a more negative Δ G . The notably more negative values for chitosan beads may be linked to their higher adsorption capacity. Table 4 Thermodynamic parameters of amoxicillin adsorption by chitosan and alginate beads. T \(\varDelta G\) (kJ mol − 1 ) \(\varDelta H\) (kJ mol − 1 ) \(\varDelta S\) (kJ mol − 1 K − 1 ) Chitosan Alginate Chitosan Alginate Chitosan Alginate 5°C -1.5 \(\pm 0.2\) -0.10 \(\pm\) 0.01 20°C -2.8 \(\pm\) 0.2 -0.30 \(\pm\) 0.01 20.6 \(\pm 0.8\) 13.8 \(\pm\) 0.4 0.080 \(\pm\) 0.001 0.049 \(\pm\) 0.001 35°C -3.9 \(\pm\) 0.1 -1.60 \(\pm\) 0.01 Mean \(\pm\) standard deviation (n = 3) The positive Δ S value indicates an augmentation in system disorder at the solid-liquid interface following adsorption. At the same time, the positive Δ H value is ascribed to the solvation of amoxicillin molecules by the solvent. As a result, the energy needed to overcome solvation exceeded the energy released during the bond formation between the adsorbent and the adsorbate. Similar results are found in the literature regarding the adsorption of amoxicillin by Mirizadeh et al. ( 2024 ) (magnetic chitosan/microalgae biocomposites) and Yeo et al. ( 2023 ) (bentonite-chitosan composite). Both studies reported that the adsorption process was spontaneous and endothermic. Enthalpy values around 20 kJ mol⁻¹ and 40 kJ mol⁻¹ are indicative of physical adsorption. Typically, this holds true for weak Van der Waals forces. However, it is possible that hydrogen bonding occurs between the beads and amoxicillin, given the presence of nitrogen, oxygen, and hydrogen atoms. 4. Conclusion In this study, chitosan and alginate beads, observed through scanning electron microscopy, exhibit spherical shapes, with chitosan displaying higher roughness and porosity. Chitosan's superior adsorption capacity is attributed to its surface characteristics. At pH 4, optimal conditions for amoxicillin adsorption on chitosan and alginate beads are achieved. The literature reports diverse adsorption capacities for various adsorbents, but chitosan and alginate beads developed in our study stand out for their ease of preparation and efficiency. In the kinetics study, chitosan achieves an adsorption capacity of 78.6 mg g⁻¹ in 200 minutes, while alginate reaches 71.3 mg g⁻¹ in 250 minutes. Thermodynamic parameters indicate physical adsorption, with external diffusion for chitosan and internal diffusion for alginate as the rate-limiting steps, probably related to the different surface morphology of the beads. Temperature increase enhances adsorption capacity due to amoxicillin's solvation effects. The Freundlich model fits both chitosan and alginate beads, indicating non-homogeneous surfaces with positive cooperativity. Comparing our results with those in the literature, the beads used in this study require fewer steps to be synthesized and a smaller quantity of chemicals. Additionally, alginate beads demonstrated a superior adsorption capacity compared to what was reported in the literature. Declarations Ethical Approval Not applicable Consent to Participate Not applicable Consent to Publish Not applicable Competing interests The authors have no competing interests as defined by Springer, or other interests that might be perceived to influence the results and/or discussion reported in this paper. Funding Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq/Brazil); Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP/Brazil; Grant 2022/05336-6); Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES/Brazil: Finance Code 001 and PNPD program). Authors' contributions Beatriz K. Tokura (methodology, formal analysis resources); Natália S. Germano (methodology, formal analysis resources); Cláudio P. Pinheiro (conceptualization, methodology, formal analysis resources, writing and original draft, visualization); Igor T. L. Bresolin (conceptualization, funding, review and editing, supervision), and Mariana A. de Moraes (conceptualization, funding, review and editing, supervision). Availability of data and materials Data will be provided upon request of corresponding author. References Abed M, Faisal AAH (2023) Green Synthesis of Calcium/Iron-Layered Double Hydroxides-Sodium Alginate Nanoadsorbent as Reactive Barrier for Antibiotic Amoxicillin Removal from Groundwater. Adsorpt. Sci. Technol., 2023, 1475278. https://doi.org/10.1155/2023/1475278 Adriano WS et al (2005) Adsorption of amoxicillin on chitosan beads: Kinetics, equilibrium and validation of finite bath models. Biochem Eng J 27(2):132–137. https://doi.org/10.1016/j.bej.2005.08.010 Adzmi F et al (2012) Preparation, characterisation and viability of encapsulated Trichoderma harzianum UPM40 in alginate-montmorillonite clay. J Microencapsul 29(3):205–210. https://doi.org/10.3109/02652048.2012.659286 Al-Saidi S et al (2023) Amoxicillin removal from medical wastewater using an eco-friendly aqueous two-phase extraction system. Sep Sci Technol 58(1):61–74. https://doi.org/10.1080/01496395.2022.2102998 Alhattab ZD et al (2023) Highly adsorption of alginate/bentonite impregnated TiO2 beads for wastewater treatment: Optimization, kinetics, and regeneration studies. Casp J Environ Sci 21(3):657–664. https://doi.org/10.22124/CJES.2023.6943 Andreozzi R et al (2004) Antibiotics in the environment: Occurrence in Italian STPs, fate, and preliminary assessment on algal toxicity of amoxicillin. Environ Sci Technol 38(24):6832–6838. https://doi.org/10.1021/es049509a Bankole OM et al (2022) Amoxicillin Encapsulation on Alginate/Magnetite Composite and Its Antimicrobial Properties Against Gram-Negative and Positive Microbes. Biosci Nanosci 12(4):1136–1149. https://doi.org/10.1007/s12668-022-01038-1 Barbooti MM, Zahraw SH (2020) Removal of amoxicillin from water by adsorption on water treatment residues. Bagh Sci J 17(3):1071. http://dx.doi.org/10.21123/bsj.2020.17.3(Suppl.).1071 Benettayeb A et al (2023) Chitosan Nanoparticles as Potential Nano-Sorbent for Removal of Toxic Environmental Pollutants. Nanomater 13(3):447. https://doi.org/10.3390/nano13030447 Berg J, Seiffert S (2023) Composite hydrogels based on calcium alginate and polyethyleneimine for wastewater treatment. J Polym Sci 61(18):2203–2222. https://doi.org/10.1002/pol.20230215 Câmara AS et al (2020) Chitosan-coated sand and its application in a fixed-bed column to remove dyes in simple, binary, and real systems. Environ Sci Pollut Res 27:37938–37945. https://doi.org/10.1007/s11356-020-09924-5 Chayid MA, Ahmed MJ (2015) Amoxicillin adsorption on microwave prepared activated carbon from Arundo donax Linn: Isotherms, kinetics, and thermodynamics studies. J Environ Chem Eng 3(3):1592–1601. https://doi.org/10.1016/j.jece.2015.05.021 Cohen R et al (2023) The shortage of amoxicillin: an escalating public health crisis in pediatrics faced by several western countries. J Pediatr 257. https://doi.org/10.1016/j.jpeds.2023.01.001 Danalioğlu ST et al (2017) Efficient removal of antibiotics by a novel magnetic adsorbent: Magnetic activated carbon/chitosan (MACC) nanocomposite. J Mol Liq 240:589–596. https://doi.org/10.1016/j.molliq.2017.05.131 De Marco BA et al (2017) Characteristics, properties and analytical methods of amoxicillin: a review with green approach. Crit Rev Anal Chem 47(3):267–277. https://doi.org/10.1080/10408347.2017.1281097 Dey SC et al (2016) Preparation, characterization and performance evaluation of chitosan as an adsorbent for remazol red. IJLRET 2(2):52–62 Ding S et al (2023) Pharmacokinetic Interaction of Anaprazole, Amoxicillin and Clarithromycin after Single-Dose Simultaneous Administration and the Effect of Adding Bismuth on Their Pharmacokinetics in Healthy Male Chinese Subjects. Eur J Drug Metab Pharmacokinet 48(2):121–132. https://doi.org/10.1007/s13318-022-00810-8 Donnelly JP et al (2024) Impact of reducing time-to-antibiotics on sepsis mortality, antibiotic use, and adverse events. Ann Am Thorac Soc 21(1):94–101. https://doi.org/10.1513/AnnalsATS.202306-505OC El-Khaiary MI, Malash GF (2011) Common data analysis errors in batch adsorption studies. Hydrometall 105(3–4):314–320. https://doi.org/10.1016/j.hydromet.2010.11.005 Estrada-Villegas GM et al (2020) PVGA/Alginate-AgNPs hydrogel as absorbent biomaterial and its soil biodegradation behavior. Polym Bull 77(8):4147–4166. https://doi.org/10.1007/s00289-019-02966-x Gao X et al (2020) Adsorption of heavy metal ions by sodium alginate based adsorbent-a review and new perspectives. Int J Biol Macromol 164:4423–4434. https://doi.org/10.1016/j.ijbiomac.2020.09.046 Georgin J et al (2023) Main advances and future prospects in the remediation of the antibiotic amoxicillin with a focus on adsorption technology: A critical review. J Water Process Eng 56:104407. https://doi.org/10.1016/j.jwpe.2023.104407 Gerente C et al (2007) Application of chitosan for the removal of metals from wastewaters by adsorption—mechanisms and models review. Crit Rev Environ Sci Technol 37(1):41–127. https://doi.org/10.1080/10643380600729089 Gupta A et al (2023) A review on antibiotics pervasiveness in the environment and their removal from wastewater. Sep Sci Technol 58(2):326–344. https://doi.org/10.1080/01496395.2022.2110120 Karimi S, Namazi H (2022) Magnetic alginate/glycodendrimer beads for efficient removal of tetracycline and amoxicillin from aqueous solutions. Int J Biol Macromol 205:128–140. https://doi.org/10.1016/j.ijbiomac.2022.02.066 Kaur A, Maity C (2020) Amoxicillin removal from an aqueous solution by adsorption using graphene oxide/calcium alginate biocomposite. J Phys Conf Ser 1531(1):012109. https://doi.org/10.1088/1742-6596/1531/1/012109 Khan MNN et al (2023) Alteration of tecoma chip wood waste into microwave-irradiated activated carbon for amoxicillin removal: Optimization and batch studies. Arab J Chem 16(10):105110. https://doi.org/10.1016/j.arabjc.2023.105110 Maswadeh H (2017) Incompatibility of paracetamol with pediatric suspensions containing amoxicillin, azithromycin and cefuroxime axetil. Pharm Pharm 8(11):355–368. https://doi.org/10.4236/pp.2017.811026 Mirizadeh S et al (2024) Efficient removal of tetracycline, ciprofloxacin, and amoxicillin by novel magnetic chitosan/microalgae biocomposites. Sep Purif Technol 329:125115. https://doi.org/10.1016/j.seppur.2023.125115 Moradi O et al (2022) Removal of pharmaceuticals (diclofenac and amoxicillin) by maltodextrin/reduced graphene and maltodextrin/reduced graphene/copper oxide nanocomposites. Chemosphere 299:134435. https://doi.org/10.1016/j.chemosphere.2022.134435 Moro TR et al (2017) Adsorption of pharmaceuticals in water through lignocellulosic fibers synergism. Chemosphere 171:57–65. https://doi.org/10.1016/j.chemosphere.2016.12.040 Mosavi SS et al (2023) Removal of amoxicillin antibiotic from polluted water by a magnetic bionanocomposite based on carboxymethyl tragacanth gum-grafted-polyaniline. Water 15(1):202. https://doi.org/10.3390/w15010202 Narkar M et al (2010) Stomach-specific controlled release gellan beads of acid-soluble drug prepared by ionotropic gelation method. AAPS PharmSciTech 11:267–277. https://doi.org/10.1208/s12249-010-9384-1 Newton AMJ et al (2014) Effect of carbopol 940 on drug release profile and floating characteristics of floating drug delivery system of amoxicillin trihydrate using HPMC different grades. J Appl Biopharm Pharmacokinet 2:29–39. http://dx.doi.org/10.14205/2309-4435.2014.02.01.4 Patel M et al (2019) Pharmaceuticals of emerging concern in aquatic systems: chemistry, occurrence, effects, and removal methods. Chem Rev 119(6):3510–3673. https://doi.org/10.1021/acs.chemrev.8b00299 Patel YL et al (2006) The effect of drug concentration and curing time on processing and properties of calcium alginate beads containing metronidazole by response surface methodology. AAPS PharmSciTech 7:E24–E30. https://doi.org/10.1208/pt070486 Perwitasari DS et al (2021) Langmuir and Freundlich isotherm approximation on adsorption mechanism of chrome waste by using tofu dregs. NSTP 106–112. http://dx.doi.org/10.11594/nstp.2021.1417 Pinheiro CP et al (2021) Anthocyanins concentration by adsorption onto chitosan and alginate beads: Isotherms, kinetics and thermodynamics parameters. IJBM 166:934–939. https://doi.org/10.1016/j.ijbiomac.2020.10.250 Pinheiro CP et al (2019) Chitosan-coated different particles in spouted bed and their use in dye continuous adsorption system. ESPR 26:28510–28523. https://doi.org/10.1007/s11356-019-04905-9 Rocher V et al (2008) Removal of organic dyes by magnetic alginate beads. Water Res 42(4–5):1290–1298. https://doi.org/10.1016/j.watres.2007.09.024 Sadiq AC et al (2021) A decade development in the application of chitosan-based materials for dye adsorption: A short review. Int J Biol Macromol 191:1151–1163. https://doi.org/10.1016/j.ijbiomac.2021.09.179 Vedula SS, Yadav GD (2023) Synthesis and application of environment friendly membranes of chitosan and chitosan-PTA for removal of copper (II) from wastewater. Indian Chem Eng 65(1):51–77. https://doi.org/10.1080/00194506.2022.2093636 Venkateswarlu K (2017) Evaluation of glibenclamide microspheres for sustained release. J Pharm Pharmacogn Res 5(2):78–87 Vieira MLG et al (2019) Chitosan and cyanoguanidine-crosslinked chitosan coated glass beads and its application in fixed bed adsorption. Chem Eng Commun 206(11):1474–1486. https://doi.org/10.1080/00986445.2019.1581618 Watkinson AJ, Murby EJ, Costanzo SD (2007) Removal of antibiotics in conventional and advanced wastewater treatment: implications for environmental discharge and wastewater recycling. Water Res 41(18):4164–4176. https://doi.org/10.1016/j.watres.2007.04.005 Xing Zha S et al (2013) The removal of amoxicillin from wastewater using organobentonite. J Environ Manage 129:569–576. https://doi.org/10.1016/j.jenvman.2013.08.032 Yazidi A et al (2020) Adsorption of amoxicillin and tetracycline on activated carbon prepared from durian shell in single and binary systems: Experimental study and modeling analysis. Chem Eng J 379:122320. https://doi.org/10.1016/j.cej.2019.122320 Yeo JYJ et al (2023) Experimental and modelling study of adsorption isotherms of amoxicillin, ampicillin and doripenem on bentonite-chitosan composite. S Afr J Chem Eng 43(1):38–45. https://doi.org/10.1016/j.sajce.2022.09.013 Zuccato E et al (2010) Source, occurrence and fate of antibiotics in the Italian aquatic environment. J Hazard Mater 179(1–3):1042–1048. https://doi.org/10.1016/j.jhazmat.2010.03.110 Cite Share Download PDF Status: Published Journal Publication published 28 Oct, 2024 Read the published version in Environmental Science and Pollution Research → Version 1 posted Editorial decision: Major Revision 18 Jun, 2024 Reviewers agreed at journal 20 May, 2024 Reviewers invited by journal 20 May, 2024 Editor invited by journal 20 May, 2024 Editor assigned by journal 03 May, 2024 First submitted to journal 01 May, 2024 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-4331760","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":304742034,"identity":"89486b33-95a2-4e9c-9a36-3022fcd9ee5f","order_by":0,"name":"Claudio Pereira Pinheiro","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA6klEQVRIiWNgGAWjYDACZgY2BgYDBgY29uYDQIYcSIyNOC38PMcSgAxjIrTAFEjOyAFqZCBCizk777EHHwruyRncyPkmXVBgICc/u4HtcQUeLZbNfOmGMwyKjQ3OvN0mPcPAwNjgzgF2wzN4tBgc5jGT5jFISNxwPHcbkPEncYNEAptkAyEtf0BaDuQ8A2oxqJ8/gxgtDEAtMzty2EBaEhhuENBi2cxjJtljkGAMDGRja6AWww13DrYb4tNizn/GTOLHnwQ5YFQ+vM3zx0BefnbzsYd4HYYpJMGITwN2LXg1jIJRMApGwQgEAASORV2OSG+eAAAAAElFTkSuQmCC","orcid":"https://orcid.org/0009-0006-8344-7124","institution":"UNIFESP: Universidade Federal de Sao Paulo","correspondingAuthor":true,"submittingAuthor":false,"prefix":"","firstName":"Claudio","middleName":"Pereira","lastName":"Pinheiro","suffix":""},{"id":304742035,"identity":"02044d79-b196-4a21-aaaa-9556672ec7e4","order_by":1,"name":"Beatriz Kaori Tokura","email":"","orcid":"","institution":"Universidade Federal de São Paulo: Universidade Federal de Sao Paulo","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Beatriz","middleName":"Kaori","lastName":"Tokura","suffix":""},{"id":304742036,"identity":"9eae9c56-1acc-4434-80c0-ac075758a950","order_by":2,"name":"Natália Soares Germano","email":"","orcid":"","institution":"Universidade Federal de São Paulo: Universidade Federal de Sao Paulo","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Natália","middleName":"Soares","lastName":"Germano","suffix":""},{"id":304742037,"identity":"451af049-08cb-41e5-ab84-8eb29ae3f8dd","order_by":3,"name":"Mariana Agostini de Moraes","email":"","orcid":"","institution":"UNICAMP: Universidade Estadual de Campinas","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Mariana","middleName":"Agostini","lastName":"de Moraes","suffix":""},{"id":304742038,"identity":"cf39b648-3201-48f9-a99d-fb481fb62e10","order_by":4,"name":"Igor Tadeu Lazzarotto Bresolin","email":"","orcid":"https://orcid.org/0000-0001-9868-7362","institution":"Universidade Federal de São Paulo: Universidade Federal de Sao Paulo","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Igor","middleName":"Tadeu Lazzarotto","lastName":"Bresolin","suffix":""}],"badges":[],"createdAt":"2024-04-26 22:48:43","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4331760/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4331760/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s11356-024-35293-4","type":"published","date":"2024-10-28T16:21:51+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":57483525,"identity":"bab79272-0ca6-4691-b92b-1e722ae82a67","added_by":"auto","created_at":"2024-05-31 09:37:00","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":151165,"visible":true,"origin":"","legend":"\u003cp\u003eFlowchart of the study\u003c/p\u003e","description":"","filename":"image1.png","url":"https://assets-eu.researchsquare.com/files/rs-4331760/v1/85df45eff23e92de0d8d2239.png"},{"id":57483522,"identity":"c988c70b-598c-419b-9f5e-b0bf7672e013","added_by":"auto","created_at":"2024-05-31 09:36:59","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":1171073,"visible":true,"origin":"","legend":"\u003cp\u003eSEM of the (a) alginate and (b) chitosan beads, at magnifications of 65×, 1000×, and 2500×\u003c/p\u003e","description":"","filename":"image2.png","url":"https://assets-eu.researchsquare.com/files/rs-4331760/v1/80934bab8c1c3547a3b4627a.png"},{"id":57483521,"identity":"83041aec-8224-493b-9e63-07e48939237b","added_by":"auto","created_at":"2024-05-31 09:36:59","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":41049,"visible":true,"origin":"","legend":"\u003cp\u003eTGA thermogram of the (a) alginate and (b) chitosan beads\u003c/p\u003e","description":"","filename":"image3.png","url":"https://assets-eu.researchsquare.com/files/rs-4331760/v1/c144f2dacdcfcf9f790d2bd0.png"},{"id":57483523,"identity":"864f6627-66f8-4aa6-9588-44d7c1903e16","added_by":"auto","created_at":"2024-05-31 09:37:00","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":29476,"visible":true,"origin":"","legend":"\u003cp\u003eDSC thermograms of the (a) alginate and (b) chitosan beads\u003c/p\u003e","description":"","filename":"image4.png","url":"https://assets-eu.researchsquare.com/files/rs-4331760/v1/8ca3030a91443afb49dc50a6.png"},{"id":57483526,"identity":"a391c25b-0813-422a-b76e-c5007265c0d9","added_by":"auto","created_at":"2024-05-31 09:37:00","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":37622,"visible":true,"origin":"","legend":"\u003cp\u003eStudy of amoxicillin adsorption kinetics by alginate and chitosan beads\u003c/p\u003e","description":"","filename":"image5.png","url":"https://assets-eu.researchsquare.com/files/rs-4331760/v1/c071ccb3d4a9541c707944c1.png"},{"id":57483909,"identity":"1c12edc6-eded-4dd9-9802-69ae4610ec89","added_by":"auto","created_at":"2024-05-31 09:45:00","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":96109,"visible":true,"origin":"","legend":"\u003cp\u003eAdsorption isotherms of amoxicillin onto a) alginate and b) chitosan beads\u003c/p\u003e","description":"","filename":"image6.png","url":"https://assets-eu.researchsquare.com/files/rs-4331760/v1/9d3b282454f5a17f3bc20a0b.png"},{"id":68207416,"identity":"0150844a-4384-4cb8-b7d7-374971a45778","added_by":"auto","created_at":"2024-11-04 16:37:15","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2273614,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4331760/v1/603fb643-9843-4419-8f47-0fca208b37b0.pdf"}],"financialInterests":"","formattedTitle":"Adsorption of amoxicillin by chitosan and alginate biopolymers composite beads.","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eAntibiotics such as amoxicillin are substances capable of eliminating or inhibiting the multiplication of bacteria (Donnelly et al. \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). Amoxicillin belongs to the penicillin class, being one of the most prescribed medications in the United States, with over 25\u0026nbsp;million prescriptions in 2022 alone (Cohen et al. \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Amoxicillin continues with an exponential increase in prescriptions worldwide (Georgin et al. 2020). However, the substance is excreted in the urine within the first hours without structure alteration. The estimated percentage of the administered amoxicillin dose excreted in the urine without undergoing structural alterations ranges between 60\u0026ndash;80% (Ding et al. \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Consequently, amoxicillin is one of the most commonly found antibiotics in wastewater (Al-Saidi et al. \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Some studies have reported the presence of amoxicillin in concentrations ranging from ng L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e to mg L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e in domestic wastewater in several world regions (Andreozzi et al. \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2004\u003c/span\u003e; Watkinson et al. \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e2007\u003c/span\u003e; Zuccato et al. \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e2010\u003c/span\u003e; Patel et al. \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2019\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe occurrence of amoxicillin in wastewater poses a potential risk due to its direct biological action on microorganisms, leading to the development of resistant bacteria that can be transmitted from animals to humans, as amoxicillin has trophic magnification capability (Gupta et al. \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). A significant issue with amoxicillin is that it may pass through wastewater treatment plants intact and might not be detected by conventional methods due to its low concentration. Therefore, it is necessary to study techniques that complement traditional water and wastewater treatments.\u003c/p\u003e \u003cp\u003eAdsorption, involving the transfer of a substance from a fluid phase (adsorbate) to a solid phase (adsorbent), proves to be a promising technique. The advantages of adsorption include its relatively low cost, high efficiency, operational ease, possible regeneration of the adsorbent, and versatility in eliminating various pharmaceuticals, regardless of their specific chemical properties (Moro et al. \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2017\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIt is widely accepted that standard liquid/solid adsorption involves film diffusion, intraparticle diffusion, and mass action. In the case of physical adsorption, mass action is a rapid process and may be inconsequential for kinetic studies. Consequently, the kinetic aspect of adsorption is typically governed by either liquid film diffusion or intraparticle diffusion, with one of these processes serving as the rate-limiting step.\u003c/p\u003e \u003cp\u003eAdsorption is adjustable to different operational conditions, such as pH, temperature, and drug concentration. The pH of the medium influences the charge of the adsorbent and adsorbate, providing a straightforward way to control the adsorptive properties. Thus, it is possible to conduct adsorption and desorption through pH or ionic strength variations (Pinheiro et al. \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Furthermore, while a variety of adsorbents can be utilized, biopolymers emerge as particularly noteworthy when environmental considerations are taken into account. In this context, natural polymers, such as chitosan and alginate, have been explored as potential green adsorbents for wastewater treatment for adsorption of different contaminants, such as dyes (Sadiq et al. \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Rocher et al. \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e2008\u003c/span\u003e) and metal ions (Gerente et al. \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2007\u003c/span\u003e; Gao et al. \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2020\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eChitosan is obtained from chitin through a deacetylation reaction process in alkaline medium, resulting in a molecular structure closely resembling that of chitin (Benettayeb et al. \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2023\u003c/span\u003e) However, chitosan has a higher number of free amino groups in its polymeric chain, allowing its use as a biomaterial in microparticle, gel, and membrane shapes. Typically, chitosan has a positive surface charge at pH values below 6 (Vedula and Yadav, \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Alginate, on the other hand, is a polysaccharide extracted from brown seaweeds, specifically \u003cem\u003ePhaeophyta\u003c/em\u003e. One of its characteristics is its selective binding ability with multivalent cations, especially calcium ions, which is a prerequisite for its gel-forming capacity (Berg and Seiffert, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Normally, the \u003cem\u003epK\u003c/em\u003e\u003csub\u003e\u003cem\u003ea\u003c/em\u003e\u003c/sub\u003e of alginate is in the range of 3.3 to 3.7 for the carboxylic groups present in its structure. Therefore, alginate should exhibit a positive charge at pH below 3 and a negative charge above it, due to the carboxyl groups present in its structure. Amoxicillin displays amphoteric properties due to its various functional groups: carboxylic (\u003cem\u003epK\u003c/em\u003e\u003csub\u003ea1\u003c/sub\u003e = 2.7), amino (\u003cem\u003epK\u003c/em\u003e\u003csub\u003ea2\u003c/sub\u003e = 7.5), and phenolic hydroxyl (\u003cem\u003epK\u003c/em\u003e\u003csub\u003ea3\u003c/sub\u003e = 9.6) (De Marco et al., \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2017\u003c/span\u003e).). So, the isoelectric point (\u003cem\u003epI\u003c/em\u003e) of amoxicillin can vary depending on specific conditions. However, typically, the \u003cem\u003epI\u003c/em\u003e of amoxicillin falls within the pH range of its two \u003cem\u003epK\u003c/em\u003e\u003csub\u003ea\u003c/sub\u003e values, which are around 2.7 and 7.5. Typically, amoxicillin exhibits a cationic characteristic at pH values below 2.7 (Adriano et al., \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2005\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eSeveral adsorbents have been utilized for drug adsorption; however, many are challenging to synthesize. Hence, the use of chitosan and alginate beads emerges as promising alternatives, given their relatively simple synthesis process. Therefore, it is necessary to study the interaction between chitosan and alginate beads adsorbents with amoxicillin at different pH levels, and subsequently, the influence of temperature, as the kinetic aspect of adsorption is governed by either liquid film diffusion or intraparticle diffusion.\u003c/p\u003e"},{"header":"2. Material and methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Material\u003c/h2\u003e \u003cp\u003eChitosan\u0026thinsp;\u0026ge;\u0026thinsp;75% deacetylated from shrimp shells and alginic acid sodium salt from brown algae were acquired from Sigma-Aldrich (USA). Amoxicillin was purchased commercially; each capsule contains 574 mg of tri-hydrated amoxicillin. Other chemicals were of analytical grade.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Chitosan and alginate solution preparation\u003c/h2\u003e \u003cp\u003eChitosan was dissolved in a 1% acetic acid solution (v v\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) at a ratio of 1 g per 50 mL, while alginate was dissolved in ultrapure water at a ratio of 1 g per 50 mL. Both solutions were maintained under constant agitation and at a consistent temperature.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3 Preparation of the beads\u003c/h2\u003e \u003cp\u003eThe Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e presents the general flowchart of the study.\u003c/p\u003e \u003cp\u003eThe beads were formed using dripping techniques, with a burette positioned 4 cm away from the appropriate coagulating solution. For chitosan, a 1 mol/L NaOH solution was employed, and for alginate, a 20% CaCl\u003csub\u003e2\u003c/sub\u003e solution was utilized as coagulation solution. Subsequently, the beads were allowed to rest for 48 hours before undergoing a washing process until a neutral pH was achieved. Finally, they were filtered (Pinheiro et al. \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). The mean diameter was measured using a micrometer.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e\u003cem\u003e2.4 Scanning electron microscopy\u003c/em\u003e (\u003cem\u003eSEM\u003c/em\u003e)\u003c/h2\u003e \u003cp\u003eMorphological characterization was conducted using scanning electron microscopy (SEM). The SEM JSM-6610LV (JEOL, Japan) was employed, operating at an acceleration voltage of 10 kV and a current of 50 mA. Prior to SEM analysis, the samples underwent gold coating.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e\u003cem\u003e2.5 Thermogravimetry\u003c/em\u003e (\u003cem\u003eTGA\u003c/em\u003e) \u003cem\u003eand differential scanning calorimetry\u003c/em\u003e (\u003cem\u003eDSC\u003c/em\u003e)\u003c/h2\u003e \u003cp\u003eTGA analyses were conducted using the DTG-60H analyzer, while differential scanning calorimetry (DSC) analyses were performed with the DSC-60 analyzer, both from Shimadzu (Japan). For TGA, the temperature range employed was 25 to 600\u0026deg;C, with a heating rate of 10\u0026deg;C min⁻\u0026sup1; and a nitrogen flow rate of 50 mL min⁻\u0026sup1;. DSC experiments involved heating from room temperature to 150 \u0026ordm;C, followed by cooling to 10 \u0026ordm;C through a cooling ramp, and subsequent heating to 250 \u0026ordm;C, at a heating rate of 10\u0026deg;C min⁻\u0026sup1; under a nitrogen atmosphere.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003e2.6 Adsorption\u003c/h2\u003e \u003cp\u003eThe concentration of the amoxicillin solution was determined through a standard curve using a spectrophotometer at a wavelength of 279 nm. A Revolver-type tube rotator (Thermo Scientific, USA) was used to provide end-over-end agitation.\u003c/p\u003e \u003cp\u003eThe determination of the optimum pH was conducted employing 1 g of adsorbent and a concentration of 300 mg L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e of amoxicillin, while maintaining constant temperature and agitation rate. The pH of each solution was adjusted using different proportions of disodium phosphate and citric acid (Mcllvaine buffer). After identifying the optimal pH, the kinetics study was conducted under the same conditions.\u003c/p\u003e \u003cp\u003eAdsorption isotherms were performed at three different temperatures (5\u0026deg;C, 20\u0026deg;C, and 35\u0026deg;C), varying the concentration of amoxicillin from 50 to 300 mg L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, under the same conditions mentioned earlier. The adsorption capacity was calculated by Eq.\u0026nbsp;\u003cspan refid=\"Equ1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003cdiv id=\"Equ1\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ1\" name=\"EquationSource\"\u003e\n$${q}_{e}=\\frac{\\left({C}_{0}-{C}_{e}\\right)}{m}V$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e1\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003ewhere \u003cem\u003eq\u003c/em\u003e\u003csub\u003e\u003cem\u003ee\u003c/em\u003e\u003c/sub\u003e is adsorbed amount (mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), \u003cem\u003eC\u003c/em\u003e\u003csub\u003e\u003cem\u003e0\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003eC\u003c/em\u003e\u003csub\u003e\u003cem\u003ee\u003c/em\u003e\u003c/sub\u003e are the initial and equilibrium amoxicillin concentrations in the liquid phase (mg L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), respectively; \u003cem\u003em\u003c/em\u003e is the adsorbent mass (g) and \u003cem\u003eV\u003c/em\u003e is the volume of the solution (L),\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003e2.7 Kinetics and adsorption isotherm models\u003c/h2\u003e \u003cp\u003eIn the kinetics study, the adsorption process is consistently influenced by either liquid film diffusion or intraparticle diffusion, where one of these mechanisms serves as the rate-limiting step. Consequently, two models were applied to the data: an external diffusion model (Boyd's external diffusion, Eq.\u0026nbsp;4) and an internal diffusion model (Weber and Morris, Eq.\u0026nbsp;\u003cspan refid=\"Equ2\" class=\"InternalRef\"\u003e5\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cem\u003eq\u003c/em\u003e \u003csub\u003e \u003cem\u003et\u003c/em\u003e \u003c/sub\u003e \u003cem\u003e= q\u003c/em\u003e\u003csub\u003e\u0026infin;\u003c/sub\u003e(1-\u003cem\u003ee\u003c/em\u003e\u003csup\u003e\u003cem\u003e\u0026minus;\u0026thinsp;Rt\u003c/em\u003e\u003c/sup\u003e) (4)\u003cdiv id=\"Equ2\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ2\" name=\"EquationSource\"\u003e\n$${q}_{t}={k}_{\\text{W}\\\u0026amp;\\text{M}}{t}^{1/2}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e5\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003ewhere \u003cem\u003eq\u003c/em\u003e\u003csub\u003e\u0026infin;\u003c/sub\u003e is the equilibrium adsorption capacity at infinite time (mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), \u003cem\u003et\u003c/em\u003e is the adsorption time (h), \u003cem\u003eR\u003c/em\u003e is the rate coefficient (h\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) and \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({k}_{\\text{W}\\\u0026amp;\\text{M}}\\)\u003c/span\u003e\u003c/span\u003e is the intraparticle diffusion coefficient (mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e h\u003csup\u003e\u0026minus;\u0026thinsp;1/2\u003c/sup\u003e)\u003c/p\u003e \u003cp\u003eIn the study of adsorption isotherms, Langmuir (Eq.\u0026nbsp;\u003cspan refid=\"Equ3\" class=\"InternalRef\"\u003e6\u003c/span\u003e) and Freundlich (Eq.\u0026nbsp;\u003cspan refid=\"Equ4\" class=\"InternalRef\"\u003e7\u003c/span\u003e) parameters were fitted to the experimental data.\u003cdiv id=\"Equ3\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ3\" name=\"EquationSource\"\u003e\n$${q}_{e}=\\frac{{q}_{m}{{K}_{d}C}_{e}}{1+{{K}_{d}C}_{e}}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e6\u003c/div\u003e\u003c/div\u003e\u003cdiv id=\"Equ4\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ4\" name=\"EquationSource\"\u003e\n$${q}_{e}={K}_{f}{C}_{e}^{1/n}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e7\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003e \u003cem\u003eq\u003c/em\u003e \u003csub\u003e \u003cem\u003em\u003c/em\u003e \u003c/sub\u003e is the maximum adsorption capacity in the monolayer (mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) and \u003cem\u003ek\u003c/em\u003e\u003csub\u003e\u003cem\u003ed\u003c/em\u003e\u003c/sub\u003e is the Langmuir constant (L mg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), \u003cem\u003eK\u003c/em\u003e\u003csub\u003e\u003cem\u003ef\u003c/em\u003e\u003c/sub\u003e (mol L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) is the Freundlich constant, and \u003cem\u003en\u003c/em\u003e is the heterogeneity factor.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003e2.8 Thermodynamic parameters\u003c/h2\u003e \u003cp\u003eAs per Pinheiro et al. (\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e2019\u003c/span\u003e), the change in Gibbs free energy (kJ mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) was computed utilizing Eq.\u0026nbsp;\u003cspan refid=\"Equ5\" class=\"InternalRef\"\u003e2\u003c/span\u003e, and the enthalpy and entropy parameters were ascertained through the Van't Hoff graph, as outlined in Eq.\u0026nbsp;\u003cspan refid=\"Equ6\" class=\"InternalRef\"\u003e3\u003c/span\u003e.\u003cdiv id=\"Equ5\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ5\" name=\"EquationSource\"\u003e\n$$\\varDelta {G}^{^\\circ }=-RTln\\left({\\rho }_{{H}_{2}O}{K}_{\\text{d}}\\right)$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e2\u003c/div\u003e\u003c/div\u003e\u003cdiv id=\"Equ6\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ6\" name=\"EquationSource\"\u003e\n$$ln{K}_{D}=\\frac{-\\varDelta H}{RT}+\\frac{\\varDelta S}{R}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e3\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003ewhere \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\varDelta {G}^{^\\circ }\\)\u003c/span\u003e\u003c/span\u003eis the variation in Gibbs free energy (kJ mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), \u003cem\u003eR\u003c/em\u003e is the universal gas constant (0.008314 kJ mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e K\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), \u003cem\u003eT\u003c/em\u003e is the absolute temperature (K), and \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\rho }_{{H}_{2}O}\\)\u003c/span\u003e\u003c/span\u003e is the specific weight of water (mg L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), Δ\u003cem\u003eH\u003c/em\u003e is the enthalpy (kJ mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) and Δ\u003cem\u003eS\u003c/em\u003e is the entropy (kJ mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e K\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) and \u003cem\u003eK\u003c/em\u003e\u003csub\u003ed\u003c/sub\u003e represents the thermodynamic equilibrium constant of the Langmuir model (L mg\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003e2.9 Statistical treatment\u003c/h2\u003e \u003cp\u003eNonlinear regression analysis was employed to fit the models to the experimental data, as described by Vieira et al. (\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). The calculations were carried out using the Origin\u0026reg; software from Microcal, based in the United States, and employing the iterative Levenberg-Marquardt method. To assess the quality of the fit, the coefficient of determination (\u003cem\u003eR\u003c/em\u003e\u0026sup2;) and the Pearson chi-square test (χ\u0026sup2;) were used (Eq.\u0026nbsp;\u003cspan refid=\"Equ7\" class=\"InternalRef\"\u003e8\u003c/span\u003e), following the methodology of El-Khaiary and Malash (\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2011\u003c/span\u003e). The generation of corresponding graphs were performed in the same software. All experiments were conducted in triplicate.\u003cdiv id=\"Equ7\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ7\" name=\"EquationSource\"\u003e\n$${\\chi }^{2}=\\sum \\frac{{\\left({q}_{exp}-{q}_{cal}\\right)}^{2}}{{q}_{exp}^{2}}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e8\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003ewhere \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({q}_{exp}\\)\u003c/span\u003e\u003c/span\u003e is the experimental adsorption capacity (mg L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) and \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({q}_{cal}\\)\u003c/span\u003e\u003c/span\u003e is the calculated adsorption capacity (mg L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e)\u003c/p\u003e \u003c/div\u003e"},{"header":"3. Results and discussion","content":"\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003e3.1 Characterization of the microparticles\u003c/h2\u003e \u003cp\u003eExamining the scanning electron microscopy images (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea and \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eb), one can discern that both beads display a spherical shape. Nevertheless, the surface of chitosan exhibits higher roughness and porosity compared to alginate. This feature is likely to have played an important role in enabling chitosan to attain a higher adsorbed amount than alginate across all adsorption experiments.\u003c/p\u003e \u003cp\u003eThe mean diameter measured for the wet beads was 1.89\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02 mm for chitosan and 1.98\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02 mm for alginate. After drying in a forced-air oven at 25\u0026deg;C for 24 hours, the diameters were 1.11\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02 mm for alginate (loss of 43.94\u0026thinsp;\u0026plusmn;\u0026thinsp;0,08%) and 0.98\u0026thinsp;\u0026plusmn;\u0026thinsp;0.02 mm for chitosan (loss of 48.15\u0026thinsp;\u0026plusmn;\u0026thinsp;0,07%). Therefore, chitosan experienced a greater water loss than alginate. This difference is likely attributed to the presence of amino groups in chitosan, along with its evidently higher porosity (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Adriano et al. (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2005\u003c/span\u003e) produced chitosan beads crosslinked with 5% glutaraldehyde, featuring an average diameter of 2.12 mm (wet basis). Therefore, not only do the beads of pure chitosan have their active sites unobstructed by crosslinking, but their volume is also smaller.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe TGA assesses the mass variation of the sample with respect to temperature. Figure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea shows the thermogram of alginate beads, which shows that the evaporation of water molecules occurs within the temperature range of 25\u0026deg;C to 200\u0026deg;C. This investigation reveals a substantial mass reduction initiating at 200\u0026deg;C and extending to 320\u0026deg;C, encompassing the dehydration of saccharide rings and the rupture of C\u0026ndash;O\u0026ndash;C bonds. The ultimate decomposition temperatures are observed at 500\u0026deg;C and 600\u0026deg;C, signaling a virtual cessation of mass loss (Adzmi et al. \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2012\u003c/span\u003e; Estrada-Villegas et al. \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2020\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb illustrates the thermogram of chitosan beads, in which the initial weight loss phase is evident within the temperature range of 25\u0026deg;C to 120\u0026deg;C, attributed to moisture loss (approximately 10%). Chitosan experiences non-oxidative thermal degradation under nitrogen flow, observed in the temperature span of 245\u0026deg;C to 600\u0026deg;C. This indicates the deacetylation of chitosan, involving vaporization and elimination of volatile products. The degradation process of chitosan starts with amino groups forming unsaturated structures (Dey et al. \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2016\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe DSC thermogram of alginate beads (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ea) reveals two distinct endothermic peaks at 100\u0026deg;C and 200\u0026deg;C. The first is likely attributed to water evaporation, while the second indicates a melting point.\u003c/p\u003e \u003cp\u003eThe introduction of amoxicillin into the alginate beads significantly reduces the intensity of these peaks. For the peak at 100\u0026deg;C, amoxicillin occupies the space previously filled by water (Patel et al., \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2006\u003c/span\u003e; Venkateswarlu, \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). Additionally, amoxicillin demonstrates an affinity for binding with water molecules. The second peak (200\u0026deg;C) is associated with the interaction between alginate and amoxicillin, as both possess various functional groups (Bankole et al., \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). This observation implies the molecular dispersion of drugs within the beads.\u003c/p\u003e \u003cp\u003eThe primary distinction in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ea is the peak observed around 140\u0026deg;C in the DSC thermogram of alginate and amoxicillin; however, this peak is not present in the thermogram of alginate alone. The endothermic peak around 140\u0026deg;C indicates a thermal transition in amoxicillin, potentially associated with its phase changes (Newton et al., \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). This peak is also evident in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eb (DSC thermogram of chitosan beads containing amoxicillin), contrasting with its absence in the chitosan-only thermogram.\u003c/p\u003e \u003cp\u003eThe DSC thermogram (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eb) of chitosan beads suggests that the initial peak corresponds to the evaporation of free water. However, chitosan exhibits a strong affinity for water, resulting in a large peak that follow the temperature increase. The presence of amoxicillin leads to the merging of the peak associated with water loss with the peak of thermal transition in amoxicillin, potentially connected to its phase changes, as observed in the thermogram of Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ea (Maswadeh, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). This occurs due to amoxicillin's strong affinity for water (Narkar et al. \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2010\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003e3.2 Effect of pH\u003c/h2\u003e \u003cp\u003eIn Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, it can be observed that the optimal pH for the adsorption of amoxicillin onto beads of chitosan and alginate was pH 4. As per Adriano et al. (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2005\u003c/span\u003e), amoxicillin exhibits an isoelectric point of 5.7. This distinctive feature is ascribed to the functional groups inherent in amoxicillin, namely, carboxyl (with a \u003cem\u003epK\u003c/em\u003e\u003csub\u003e\u003cem\u003ea1\u003c/em\u003e\u003c/sub\u003e of 2.68), amine (with a \u003cem\u003epK\u003c/em\u003e\u003csub\u003e\u003cem\u003ea2\u003c/em\u003e\u003c/sub\u003e of 7.49), and phenolic hydroxyl (with a \u003cem\u003epK\u003c/em\u003e\u003csub\u003e\u003cem\u003ea3\u003c/em\u003e\u003c/sub\u003e of 9.63). At the pH equal to \u003cem\u003epK\u003c/em\u003e\u003csub\u003e\u003cem\u003ea3\u003c/em\u003e\u003c/sub\u003e, the phenolic hydroxyl group undergoes deprotonation, resulting in amoxicillin carrying a double negative charge. When the pH falls within the range of \u003cem\u003epK\u003c/em\u003e\u003csub\u003e\u003cem\u003ea2\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003epK\u003c/em\u003e\u003csub\u003e\u003cem\u003ea3\u003c/em\u003e\u003c/sub\u003e values, deprotonation of the amine group takes place. At a pH value between \u003cem\u003epK\u003c/em\u003e\u003csub\u003e\u003cem\u003ea1\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003epK\u003c/em\u003e\u003csub\u003e\u003cem\u003ea2\u003c/em\u003e\u003c/sub\u003e, amoxicillin remains uncharged due to the deprotonation of the carboxylic group. Lastly, amoxicillin demonstrates a cationic characteristic at pH values lower than 2.68 (Barbooti and Zahraw, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2020\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eEffect of pH variation on the amoxicillin adsorption capacity.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAlginate\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eChitosan\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003epH\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003emg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003emg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e58.4 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e 0.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e55.4 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e 0.3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e74.2 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e 0.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e80.4 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e 0.2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e55.4 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e 0.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e62.4 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e 0.2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e30.6 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e 0.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e42.3 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e 0.1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e33.2 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e 0.2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e20.4 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e 0.3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"3\"\u003eMean \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e standard deviation (n = 3)\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eConcerning chitosan, the positive surface charge of chitosan tends to increase with a decrease in pH, below pH 6 (Camara et al. 2020). This phenomenon arises from the protonation of the amino group. In contrast, the surface charge of amoxicillin tends to remain neutral between pH 2.7 and 7.5. Therefore, at pH below 4, there is an increase in the repulsion between amoxicillin and chitosan, because amoxicillin contains an amino group that tends to be protonated with a decrease in pH. With an increase in pH, deprotonation of chitosan occurs, resulting in a diminished attraction between chitosan and amoxicillin.\u003c/p\u003e \u003cp\u003eAlginate exhibits a negative charge with an increase in pH above 3, due to the presence of the carboxylic group. The presence of the carboxylic group in alginate and the amino group in amoxicillin are likely responsible for the interaction and, consequently, adsorption, with a maximum interaction at pH 4. Adsorption above pH 6 was not feasible because alginate beads dissolved in water (Gao et al. \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2020\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIn the literature, amoxicillin adsorption has been investigated using various adsorbents, and the maximum adsorption capacity observed by fitting the Langmuir model varies widely: it ranges from 2.28 mg g⁻\u0026sup1; for Organobentonite (Xing Zha et al. \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2013\u003c/span\u003e) to 909 mg g⁻\u0026sup1; for magnetic Bionanocomposite (Mosavi et al. \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Other reported values include 7.3 mg g⁻\u0026sup1; using methylene blue (Barbooti and Zahraw, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2020\u003c/span\u003e), 135 mg g⁻\u0026sup1; at 30\u0026deg;C for activated carbon prepared from durian shell (Yazidi et al. \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2020\u003c/span\u003e), 345.4 mg g⁻\u0026sup1; for activated carbon from Arundodonax biomass (Chayid and Ahmed, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2015\u003c/span\u003e), 357 mg g⁻\u0026sup1; at pH 9 for tecomachip wood waste into microwave-irradiated adsorbent (Khan et al. \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2023\u003c/span\u003e), and 526 mg g⁻\u0026sup1; for Graphene/copper oxide nanocomposites (Moradi et al. \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2022\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eHowever, the fabrication of all these adsorbents involves numerous intricate steps and a variety of chemical reagents, making the process considerably more complex when compared to the relatively simpler production of chitosan and alginate beads. Additionally, these more complex fabrication methods may have potential ecological impacts, such as increased chemical waste generation and energy consumption.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003e3.3 Effect of contact time\u003c/h2\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e shows the adsorption kinetics of amoxicillin in alginate and chitosan beads, as well as the fitting of data to the Boyd and Weber and Morris models. Chitosan took 200 minutes to reach an adsorption capacity of 78.6 mg g⁻\u0026sup1;, while alginate took 250 minutes to reach 71.3 mg g⁻\u0026sup1;.\u003c/p\u003e \u003cp\u003eWhen adsorption is physical, the influence of mass action may be neglected. As will be demonstrated, the enthalpy obtained in this study is characteristic of physical adsorption. Therefore, adsorption is governed by either liquid film diffusion or intraparticle diffusion. Both mechanisms are often present simultaneously in many heterogeneous systems, and the overall rate of mass transfer is usually determined by the slowest step, which may vary depending on the specific conditions of the system. Experimental techniques, such as fitting experimental data to mathematical models like the Weber-Morris equation, can help elucidate the relative contributions of liquid film diffusion and intraparticle diffusion to the overall mass transfer process. Liquid film diffusion refers to the process of mass transfer that occurs as a solute in a fluid phase moves from the bulk of the fluid to the surface of a solid particle, where adsorption or reaction takes place. Intraparticle diffusion, on the other hand, occurs within the solid particles themselves. After reaching the surface of the solid, the solute must then diffuse into the pores or internal structure of the solid particle.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAccording to Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, the best-fitted model for chitosan was Boyd's external diffusion, indicating that the rate-limiting step is the external diffusion model. However, for alginate, a better fit was obtained with the Weber and Morris model, thus indicating that the rate-limiting step is the internal diffusion model. Intraparticle diffusion can be influenced by pore size, and as observed in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, the surface of chitosan exhibits higher roughness and porosity compared to alginate, which may facilitate the internal mass transfer in chitosan beads. This difference in beads morphology may explain the results regarding the rate-limiting step for adsorption observed in chitosan and alginate beads.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eParameters for the study of amoxicillin kinetics.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eChitosan\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eAlginate\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eChitosan\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eAlginate\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eBoyd's external diffusion\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003eWeber and Morris\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({\\chi }^{2}\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e74 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e 1.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e82 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e 1.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e142 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e 1.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.961 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e 0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eR\u003c/em\u003e\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.973 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e 0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.961 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e 0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.991 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e 0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.933 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e 0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({k}_{\\text{W}\\\u0026amp;\\text{M}}\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4.13\u0026thinsp;+\u0026thinsp;0.11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e5.51\u0026thinsp;+\u0026thinsp;0.057\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eq\u003c/em\u003e\u003csub\u003e\u0026infin;\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e82.72 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e 3.12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e136.75 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e 8.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eR\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.0125 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e 0.0014\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.00251 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e0.0012\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e-\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003eMean \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e standard deviation (n = 3)\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec16\" class=\"Section2\"\u003e \u003ch2\u003e3.4 Effect of temperature\u003c/h2\u003e \u003cp\u003eObserving Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e, it is evident that the increase in temperature resulted in an enhancement of the adsorption capacity. This is because amoxicillin may experience solvent solvation effects, and thus, at higher temperatures, amoxicillin has more energy to overcome solvation.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAnalyzing the results presented in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, it is noticeable that the best-fitted model for chitosan beads was the Freundlich model. Furthermore, the Freundlich constant \u003cem\u003en\u003c/em\u003e was greater than 1 in all cases, indicating that the surface of chitosan is non-homogeneous, contrary to what the Langmuir model suggests (Perwitasari et al. \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). This suggests that one adsorption site might interfere with adsorption at another site. Regarding alginate beads, generally, the Freundlich model also provided a better fit. The behavior of \u003cem\u003en\u003c/em\u003e for alginate beads was similar to that observed for chitosan beads. That is, the adsorption of one molecule favors the adsorption of another molecule, indicating positive cooperativity.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eEquilibrium isotherm parameters for amoxicillin adsorption.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003eChitosan\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c7\" namest=\"c5\"\u003e \u003cp\u003eAlginate\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"7\" nameend=\"c7\" namest=\"c1\"\u003e \u003cp\u003eLangmuir\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eT\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eq\u003c/em\u003e\u003csub\u003em\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eK\u003c/em\u003e\u003csub\u003e\u003cem\u003ed\u003c/em\u003e\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eR\u003c/em\u003e\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003eq\u003c/em\u003e\u003csub\u003em\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cem\u003eK\u003c/em\u003e\u003csub\u003e\u003cem\u003ed\u003c/em\u003e\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cem\u003eR\u003c/em\u003e\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e278\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e98.4 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e0.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.0348 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e0.0002\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.857 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e60.8 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e1.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.0191 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e0.0002\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.859 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e293\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e102.2 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm 0.9\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.057 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e0.0002\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.981 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e104.3 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e0.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.0209 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e0.0002\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.981 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e308\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e94.4 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm 0.7\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.083 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e0.0002\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.984 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e99.0 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e0.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.0344 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e0.0002\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.994 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"7\" nameend=\"c7\" namest=\"c1\"\u003e \u003cp\u003eFreundlich\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e278\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2.7 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm 0.4\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.7 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e0.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.992 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.7 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e0.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1.6 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e0.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.996 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e293\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e15.1 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm 0.5\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2.9 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm 0.2\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.991 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e10.8 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e0.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e2.5 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e0.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.991 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e308\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e11.3 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm 0.7\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2.7 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e0.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.996 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e7.1 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e0.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e2.2 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e0.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.990 \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"7\"\u003eMean \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e standard deviation (n = 3)\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eAdriano et al. (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2005\u003c/span\u003e) investigated the adsorption of amoxicillin on chitosan beads crosslinked with 5% glutaraldehyde at pH 6.5. They achieved a maximum adsorption capacity of only 8.71 mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, according to the Langmuir model. This diminished capacity is likely attributable to the glutaraldehyde, which reduces the number of active sites on the chitosan available for adsorption. Furthermore, in this study, a significantly higher maximum adsorption capacity of 102 mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e was observed, according to the Langmuir model. This disparity underscores how glutaraldehyde not only hampers drug adsorption but also complicates the synthesis of chitosan beads by introducing additional steps. Mirizadeh et al. (\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2024\u003c/span\u003e) investigated the removal of amoxicillin by magnetic chitosan/microalgae biocomposites, achieving optimal results between pH 5 and 6, obtaining a maximum adsorption capacity of 125.6 mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. Yeo et al. (\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e2023\u003c/span\u003e) investigated the adsorption of amoxicillin using a bentonite-chitosan composite and observed a maximum capacity of 66 mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e at 50\u0026deg;C. Danalioğlu et al. (\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2017\u003c/span\u003e) adsorbed amoxicillin using magnetic activated carbon/chitosan and achieved an adsorption capacity of 98 mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e for 15 mg of adsorbent; however, the pH of the medium was not controlled. Our adsorption capacity was similar to those reported in the literature; however, it is noteworthy that the adsorption sites on chitosan beads are more accessible compared to the mentioned adsorbents in the literature. This is because the beads did not undergo any crosslinking process, nor did the amino groups form chemical bonds with other compounds.\u003c/p\u003e \u003cp\u003eAbed and Faisal (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2023\u003c/span\u003e) explored the adsorption of amoxicillin using a calcium/iron-layered double hydroxides-sodium alginate nanoadsorbent at pH 7, achieving a maximum capacity of 6.7 mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e according to the Langmuir model. Kaur and Maity (\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2020\u003c/span\u003e) successfully removed amoxicillin using a graphene oxide/calcium alginate biocomposite, achieving a maximum adsorption capacity of 50 mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e at pH 6. In their study, Karimi and Namazi (\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2022\u003c/span\u003e) effectively adsorbed amoxicillin utilizing alginate/glycodendrimer beads, achieving a maximum adsorption capacity of 48.8 mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e at pH 7. Alhattab et al. (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2023\u003c/span\u003e), using alginate/bentonite-impregnated TiO\u003csub\u003e2\u003c/sub\u003e beads for amoxicillin adsorption, achieved an adsorption capacity of 85 mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e at pH 6. The adsorption capacity achieved in this study for the alginate beads was 74.2\u0026thinsp;\u0026plusmn;\u0026thinsp;0.3 mg g\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e at pH 4, higher than several previously cited adsorption capacities. Additionally, the manufacture of these aforementioned adsorbents involves numerous intricate steps and the use of various chemical reagents, significantly complicating the process compared to the relatively straightforward production of alginate beads. Furthermore, these more complex fabrication methods could potentially result in ecological ramifications, such as increased generation of chemical waste and energy consumption.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec17\" class=\"Section2\"\u003e \u003ch2\u003e3.5 Thermodynamic parameters\u003c/h2\u003e \u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e reveals that the change in Gibbs free energy (Δ\u003cem\u003eG\u003c/em\u003e) was consistently negative for both beads at all temperatures, indicating a spontaneous process. The rise in temperature further enhanced adsorption, leading to a more negative Δ\u003cem\u003eG\u003c/em\u003e. The notably more negative values for chitosan beads may be linked to their higher adsorption capacity.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eThermodynamic parameters of amoxicillin adsorption by chitosan and alginate beads.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003eT\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\varDelta G\\)\u003c/span\u003e\u003c/span\u003e (kJ mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\varDelta H\\)\u003c/span\u003e\u003c/span\u003e (kJ mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\varDelta S\\)\u003c/span\u003e\u003c/span\u003e (kJ mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e K\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eChitosan\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eAlginate\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eChitosan\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eAlginate\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eChitosan\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eAlginate\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5\u0026deg;C\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-1.5\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm 0.2\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-0.10\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e0.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e20\u0026deg;C\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-2.8\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e0.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-0.30\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e0.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e20.6\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm 0.8\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e13.8\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e0.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.080\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.049\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e35\u0026deg;C\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-3.9\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e0.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-1.60\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e0.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"7\"\u003eMean \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\pm\\)\u003c/span\u003e\u003c/span\u003e standard deviation (n = 3)\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eThe positive Δ\u003cem\u003eS\u003c/em\u003e value indicates an augmentation in system disorder at the solid-liquid interface following adsorption. At the same time, the positive Δ\u003cem\u003eH\u003c/em\u003e value is ascribed to the solvation of amoxicillin molecules by the solvent. As a result, the energy needed to overcome solvation exceeded the energy released during the bond formation between the adsorbent and the adsorbate. Similar results are found in the literature regarding the adsorption of amoxicillin by Mirizadeh et al. (\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2024\u003c/span\u003e) (magnetic chitosan/microalgae biocomposites) and Yeo et al. (\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e2023\u003c/span\u003e) (bentonite-chitosan composite). Both studies reported that the adsorption process was spontaneous and endothermic.\u003c/p\u003e \u003cp\u003eEnthalpy values around 20 kJ mol⁻\u0026sup1; and 40 kJ mol⁻\u0026sup1; are indicative of physical adsorption. Typically, this holds true for weak Van der Waals forces. However, it is possible that hydrogen bonding occurs between the beads and amoxicillin, given the presence of nitrogen, oxygen, and hydrogen atoms.\u003c/p\u003e \u003c/div\u003e"},{"header":"4. Conclusion","content":"\u003cp\u003eIn this study, chitosan and alginate beads, observed through scanning electron microscopy, exhibit spherical shapes, with chitosan displaying higher roughness and porosity. Chitosan's superior adsorption capacity is attributed to its surface characteristics.\u003c/p\u003e \u003cp\u003eAt pH 4, optimal conditions for amoxicillin adsorption on chitosan and alginate beads are achieved. The literature reports diverse adsorption capacities for various adsorbents, but chitosan and alginate beads developed in our study stand out for their ease of preparation and efficiency.\u003c/p\u003e \u003cp\u003eIn the kinetics study, chitosan achieves an adsorption capacity of 78.6 mg g⁻\u0026sup1; in 200 minutes, while alginate reaches 71.3 mg g⁻\u0026sup1; in 250 minutes. Thermodynamic parameters indicate physical adsorption, with external diffusion for chitosan and internal diffusion for alginate as the rate-limiting steps, probably related to the different surface morphology of the beads. Temperature increase enhances adsorption capacity due to amoxicillin's solvation effects. The Freundlich model fits both chitosan and alginate beads, indicating non-homogeneous surfaces with positive cooperativity.\u003c/p\u003e \u003cp\u003eComparing our results with those in the literature, the beads used in this study require fewer steps to be synthesized and a smaller quantity of chemicals. Additionally, alginate beads demonstrated a superior adsorption capacity compared to what was reported in the literature.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003ch2\u003eEthical Approval\u003c/h2\u003e \u003cp\u003eNot applicable\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eConsent to Participate\u003c/strong\u003e \u003cp\u003eNot applicable\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eConsent to Publish\u003c/strong\u003e \u003cp\u003eNot applicable\u003c/p\u003e \u003c/p\u003e\u003cp\u003e \u003ch2\u003eCompeting interests\u003c/h2\u003e \u003cp\u003eThe authors have no competing interests as defined by Springer, or other interests that might be perceived to influence the results and/or discussion reported in this paper.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eFunding\u003c/h2\u003e \u003cp\u003eConselho Nacional de Desenvolvimento Cient\u0026iacute;fico e Tecnol\u0026oacute;gico (CNPq/Brazil); Funda\u0026ccedil;\u0026atilde;o de Amparo \u0026agrave; Pesquisa do Estado de S\u0026atilde;o Paulo (FAPESP/Brazil; Grant 2022/05336-6); Coordena\u0026ccedil;\u0026atilde;o de Aperfei\u0026ccedil;oamento de Pessoal de N\u0026iacute;vel Superior (CAPES/Brazil: Finance Code 001 and PNPD program).\u003c/p\u003e\u003ch2\u003eAuthors' contributions\u003c/h2\u003e \u003cp\u003eBeatriz K. Tokura (methodology, formal analysis resources); Nat\u0026aacute;lia S. Germano (methodology, formal analysis resources); Cl\u0026aacute;udio P. Pinheiro (conceptualization, methodology, formal analysis resources, writing and original draft, visualization); Igor T. L. Bresolin (conceptualization, funding, review and editing, supervision), and Mariana A. de Moraes (conceptualization, funding, review and editing, supervision).\u003c/p\u003e\u003ch2\u003eAvailability of data and materials\u003c/h2\u003e \u003cp\u003eData will be provided upon request of corresponding author.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eAbed M, Faisal AAH (2023) Green Synthesis of Calcium/Iron-Layered Double Hydroxides-Sodium Alginate Nanoadsorbent as Reactive Barrier for Antibiotic Amoxicillin Removal from Groundwater. Adsorpt. Sci. Technol., 2023, 1475278. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1155/2023/1475278\u003c/span\u003e\u003cspan address=\"10.1155/2023/1475278\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAdriano WS et al (2005) Adsorption of amoxicillin on chitosan beads: Kinetics, equilibrium and validation of finite bath models. Biochem Eng J 27(2):132\u0026ndash;137. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.bej.2005.08.010\u003c/span\u003e\u003cspan address=\"10.1016/j.bej.2005.08.010\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAdzmi F et al (2012) Preparation, characterisation and viability of encapsulated Trichoderma harzianum UPM40 in alginate-montmorillonite clay. J Microencapsul 29(3):205\u0026ndash;210. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3109/02652048.2012.659286\u003c/span\u003e\u003cspan address=\"10.3109/02652048.2012.659286\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAl-Saidi S et al (2023) Amoxicillin removal from medical wastewater using an eco-friendly aqueous two-phase extraction system. Sep Sci Technol 58(1):61\u0026ndash;74. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1080/01496395.2022.2102998\u003c/span\u003e\u003cspan address=\"10.1080/01496395.2022.2102998\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAlhattab ZD et al (2023) Highly adsorption of alginate/bentonite impregnated TiO2 beads for wastewater treatment: Optimization, kinetics, and regeneration studies. Casp J Environ Sci 21(3):657\u0026ndash;664. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.22124/CJES.2023.6943\u003c/span\u003e\u003cspan address=\"10.22124/CJES.2023.6943\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAndreozzi R et al (2004) Antibiotics in the environment: Occurrence in Italian STPs, fate, and preliminary assessment on algal toxicity of amoxicillin. Environ Sci Technol 38(24):6832\u0026ndash;6838. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1021/es049509a\u003c/span\u003e\u003cspan address=\"10.1021/es049509a\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBankole OM et al (2022) Amoxicillin Encapsulation on Alginate/Magnetite Composite and Its Antimicrobial Properties Against Gram-Negative and Positive Microbes. Biosci Nanosci 12(4):1136\u0026ndash;1149. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s12668-022-01038-1\u003c/span\u003e\u003cspan address=\"10.1007/s12668-022-01038-1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBarbooti MM, Zahraw SH (2020) Removal of amoxicillin from water by adsorption on water treatment residues. Bagh Sci J 17(3):1071. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttp://dx.doi.org/10.21123/bsj.2020.17.3(Suppl.).1071\u003c/span\u003e\u003cspan address=\"10.21123/bsj.2020.17.3(Suppl.).1071\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBenettayeb A et al (2023) Chitosan Nanoparticles as Potential Nano-Sorbent for Removal of Toxic Environmental Pollutants. Nanomater 13(3):447. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3390/nano13030447\u003c/span\u003e\u003cspan address=\"10.3390/nano13030447\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBerg J, Seiffert S (2023) Composite hydrogels based on calcium alginate and polyethyleneimine for wastewater treatment. J Polym Sci 61(18):2203\u0026ndash;2222. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1002/pol.20230215\u003c/span\u003e\u003cspan address=\"10.1002/pol.20230215\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eC\u0026acirc;mara AS et al (2020) Chitosan-coated sand and its application in a fixed-bed column to remove dyes in simple, binary, and real systems. Environ Sci Pollut Res 27:37938\u0026ndash;37945. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s11356-020-09924-5\u003c/span\u003e\u003cspan address=\"10.1007/s11356-020-09924-5\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChayid MA, Ahmed MJ (2015) Amoxicillin adsorption on microwave prepared activated carbon from Arundo donax Linn: Isotherms, kinetics, and thermodynamics studies. J Environ Chem Eng 3(3):1592\u0026ndash;1601. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jece.2015.05.021\u003c/span\u003e\u003cspan address=\"10.1016/j.jece.2015.05.021\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCohen R et al (2023) The shortage of amoxicillin: an escalating public health crisis in pediatrics faced by several western countries. J Pediatr 257. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jpeds.2023.01.001\u003c/span\u003e\u003cspan address=\"10.1016/j.jpeds.2023.01.001\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDanalioğlu ST et al (2017) Efficient removal of antibiotics by a novel magnetic adsorbent: Magnetic activated carbon/chitosan (MACC) nanocomposite. J Mol Liq 240:589\u0026ndash;596. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.molliq.2017.05.131\u003c/span\u003e\u003cspan address=\"10.1016/j.molliq.2017.05.131\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDe Marco BA et al (2017) Characteristics, properties and analytical methods of amoxicillin: a review with green approach. Crit Rev Anal Chem 47(3):267\u0026ndash;277. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1080/10408347.2017.1281097\u003c/span\u003e\u003cspan address=\"10.1080/10408347.2017.1281097\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDey SC et al (2016) Preparation, characterization and performance evaluation of chitosan as an adsorbent for remazol red. IJLRET 2(2):52\u0026ndash;62\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDing S et al (2023) Pharmacokinetic Interaction of Anaprazole, Amoxicillin and Clarithromycin after Single-Dose Simultaneous Administration and the Effect of Adding Bismuth on Their Pharmacokinetics in Healthy Male Chinese Subjects. Eur J Drug Metab Pharmacokinet 48(2):121\u0026ndash;132. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s13318-022-00810-8\u003c/span\u003e\u003cspan address=\"10.1007/s13318-022-00810-8\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDonnelly JP et al (2024) Impact of reducing time-to-antibiotics on sepsis mortality, antibiotic use, and adverse events. Ann Am Thorac Soc 21(1):94\u0026ndash;101. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1513/AnnalsATS.202306-505OC\u003c/span\u003e\u003cspan address=\"10.1513/AnnalsATS.202306-505OC\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eEl-Khaiary MI, Malash GF (2011) Common data analysis errors in batch adsorption studies. Hydrometall 105(3\u0026ndash;4):314\u0026ndash;320. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.hydromet.2010.11.005\u003c/span\u003e\u003cspan address=\"10.1016/j.hydromet.2010.11.005\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eEstrada-Villegas GM et al (2020) PVGA/Alginate-AgNPs hydrogel as absorbent biomaterial and its soil biodegradation behavior. Polym Bull 77(8):4147\u0026ndash;4166. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s00289-019-02966-x\u003c/span\u003e\u003cspan address=\"10.1007/s00289-019-02966-x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGao X et al (2020) Adsorption of heavy metal ions by sodium alginate based adsorbent-a review and new perspectives. Int J Biol Macromol 164:4423\u0026ndash;4434. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.ijbiomac.2020.09.046\u003c/span\u003e\u003cspan address=\"10.1016/j.ijbiomac.2020.09.046\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGeorgin J et al (2023) Main advances and future prospects in the remediation of the antibiotic amoxicillin with a focus on adsorption technology: A critical review. J Water Process Eng 56:104407. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jwpe.2023.104407\u003c/span\u003e\u003cspan address=\"10.1016/j.jwpe.2023.104407\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGerente C et al (2007) Application of chitosan for the removal of metals from wastewaters by adsorption\u0026mdash;mechanisms and models review. Crit Rev Environ Sci Technol 37(1):41\u0026ndash;127. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1080/10643380600729089\u003c/span\u003e\u003cspan address=\"10.1080/10643380600729089\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGupta A et al (2023) A review on antibiotics pervasiveness in the environment and their removal from wastewater. Sep Sci Technol 58(2):326\u0026ndash;344. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1080/01496395.2022.2110120\u003c/span\u003e\u003cspan address=\"10.1080/01496395.2022.2110120\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKarimi S, Namazi H (2022) Magnetic alginate/glycodendrimer beads for efficient removal of tetracycline and amoxicillin from aqueous solutions. Int J Biol Macromol 205:128\u0026ndash;140. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.ijbiomac.2022.02.066\u003c/span\u003e\u003cspan address=\"10.1016/j.ijbiomac.2022.02.066\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKaur A, Maity C (2020) Amoxicillin removal from an aqueous solution by adsorption using graphene oxide/calcium alginate biocomposite. J Phys Conf Ser 1531(1):012109. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1088/1742-6596/1531/1/012109\u003c/span\u003e\u003cspan address=\"10.1088/1742-6596/1531/1/012109\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKhan MNN et al (2023) Alteration of tecoma chip wood waste into microwave-irradiated activated carbon for amoxicillin removal: Optimization and batch studies. Arab J Chem 16(10):105110. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.arabjc.2023.105110\u003c/span\u003e\u003cspan address=\"10.1016/j.arabjc.2023.105110\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMaswadeh H (2017) Incompatibility of paracetamol with pediatric suspensions containing amoxicillin, azithromycin and cefuroxime axetil. Pharm Pharm 8(11):355\u0026ndash;368. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.4236/pp.2017.811026\u003c/span\u003e\u003cspan address=\"10.4236/pp.2017.811026\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMirizadeh S et al (2024) Efficient removal of tetracycline, ciprofloxacin, and amoxicillin by novel magnetic chitosan/microalgae biocomposites. Sep Purif Technol 329:125115. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.seppur.2023.125115\u003c/span\u003e\u003cspan address=\"10.1016/j.seppur.2023.125115\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMoradi O et al (2022) Removal of pharmaceuticals (diclofenac and amoxicillin) by maltodextrin/reduced graphene and maltodextrin/reduced graphene/copper oxide nanocomposites. Chemosphere 299:134435. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.chemosphere.2022.134435\u003c/span\u003e\u003cspan address=\"10.1016/j.chemosphere.2022.134435\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMoro TR et al (2017) Adsorption of pharmaceuticals in water through lignocellulosic fibers synergism. Chemosphere 171:57\u0026ndash;65. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.chemosphere.2016.12.040\u003c/span\u003e\u003cspan address=\"10.1016/j.chemosphere.2016.12.040\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMosavi SS et al (2023) Removal of amoxicillin antibiotic from polluted water by a magnetic bionanocomposite based on carboxymethyl tragacanth gum-grafted-polyaniline. Water 15(1):202. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3390/w15010202\u003c/span\u003e\u003cspan address=\"10.3390/w15010202\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNarkar M et al (2010) Stomach-specific controlled release gellan beads of acid-soluble drug prepared by ionotropic gelation method. AAPS PharmSciTech 11:267\u0026ndash;277. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1208/s12249-010-9384-1\u003c/span\u003e\u003cspan address=\"10.1208/s12249-010-9384-1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNewton AMJ et al (2014) Effect of carbopol 940 on drug release profile and floating characteristics of floating drug delivery system of amoxicillin trihydrate using HPMC different grades. J Appl Biopharm Pharmacokinet 2:29\u0026ndash;39. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttp://dx.doi.org/10.14205/2309-4435.2014.02.01.4\u003c/span\u003e\u003cspan address=\"10.14205/2309-4435.2014.02.01.4\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePatel M et al (2019) Pharmaceuticals of emerging concern in aquatic systems: chemistry, occurrence, effects, and removal methods. Chem Rev 119(6):3510\u0026ndash;3673. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1021/acs.chemrev.8b00299\u003c/span\u003e\u003cspan address=\"10.1021/acs.chemrev.8b00299\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePatel YL et al (2006) The effect of drug concentration and curing time on processing and properties of calcium alginate beads containing metronidazole by response surface methodology. AAPS PharmSciTech 7:E24\u0026ndash;E30. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1208/pt070486\u003c/span\u003e\u003cspan address=\"10.1208/pt070486\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePerwitasari DS et al (2021) Langmuir and Freundlich isotherm approximation on adsorption mechanism of chrome waste by using tofu dregs. NSTP 106\u0026ndash;112. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttp://dx.doi.org/10.11594/nstp.2021.1417\u003c/span\u003e\u003cspan address=\"10.11594/nstp.2021.1417\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePinheiro CP et al (2021) Anthocyanins concentration by adsorption onto chitosan and alginate beads: Isotherms, kinetics and thermodynamics parameters. IJBM 166:934\u0026ndash;939. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.ijbiomac.2020.10.250\u003c/span\u003e\u003cspan address=\"10.1016/j.ijbiomac.2020.10.250\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePinheiro CP et al (2019) Chitosan-coated different particles in spouted bed and their use in dye continuous adsorption system. ESPR 26:28510\u0026ndash;28523. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s11356-019-04905-9\u003c/span\u003e\u003cspan address=\"10.1007/s11356-019-04905-9\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRocher V et al (2008) Removal of organic dyes by magnetic alginate beads. Water Res 42(4\u0026ndash;5):1290\u0026ndash;1298. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.watres.2007.09.024\u003c/span\u003e\u003cspan address=\"10.1016/j.watres.2007.09.024\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSadiq AC et al (2021) A decade development in the application of chitosan-based materials for dye adsorption: A short review. Int J Biol Macromol 191:1151\u0026ndash;1163. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.ijbiomac.2021.09.179\u003c/span\u003e\u003cspan address=\"10.1016/j.ijbiomac.2021.09.179\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eVedula SS, Yadav GD (2023) Synthesis and application of environment friendly membranes of chitosan and chitosan-PTA for removal of copper (II) from wastewater. Indian Chem Eng 65(1):51\u0026ndash;77. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1080/00194506.2022.2093636\u003c/span\u003e\u003cspan address=\"10.1080/00194506.2022.2093636\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eVenkateswarlu K (2017) Evaluation of glibenclamide microspheres for sustained release. J Pharm Pharmacogn Res 5(2):78\u0026ndash;87\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eVieira MLG et al (2019) Chitosan and cyanoguanidine-crosslinked chitosan coated glass beads and its application in fixed bed adsorption. Chem Eng Commun 206(11):1474\u0026ndash;1486. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1080/00986445.2019.1581618\u003c/span\u003e\u003cspan address=\"10.1080/00986445.2019.1581618\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWatkinson AJ, Murby EJ, Costanzo SD (2007) Removal of antibiotics in conventional and advanced wastewater treatment: implications for environmental discharge and wastewater recycling. Water Res 41(18):4164\u0026ndash;4176. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.watres.2007.04.005\u003c/span\u003e\u003cspan address=\"10.1016/j.watres.2007.04.005\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eXing Zha S et al (2013) The removal of amoxicillin from wastewater using organobentonite. J Environ Manage 129:569\u0026ndash;576. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jenvman.2013.08.032\u003c/span\u003e\u003cspan address=\"10.1016/j.jenvman.2013.08.032\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYazidi A et al (2020) Adsorption of amoxicillin and tetracycline on activated carbon prepared from durian shell in single and binary systems: Experimental study and modeling analysis. Chem Eng J 379:122320. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.cej.2019.122320\u003c/span\u003e\u003cspan address=\"10.1016/j.cej.2019.122320\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYeo JYJ et al (2023) Experimental and modelling study of adsorption isotherms of amoxicillin, ampicillin and doripenem on bentonite-chitosan composite. S Afr J Chem Eng 43(1):38\u0026ndash;45. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.sajce.2022.09.013\u003c/span\u003e\u003cspan address=\"10.1016/j.sajce.2022.09.013\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZuccato E et al (2010) Source, occurrence and fate of antibiotics in the Italian aquatic environment. J Hazard Mater 179(1\u0026ndash;3):1042\u0026ndash;1048. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jhazmat.2010.03.110\u003c/span\u003e\u003cspan address=\"10.1016/j.jhazmat.2010.03.110\" 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":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":true,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"environmental-science-and-pollution-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"espr","sideBox":"Learn more about [Environmental Science and Pollution Research](https://www.springer.com/journal/11356)","snPcode":"11356","submissionUrl":"https://submission.nature.com/new-submission/11356/3","title":"Environmental Science and Pollution Research","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"wastewater, renewable, Thermodynamic, kinetics, external diffusion, internal diffusion","lastPublishedDoi":"10.21203/rs.3.rs-4331760/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4331760/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eAmoxicillin is one of the most used antibiotics worldwide, and due to incomplete metabolism in the human body or inadequate disposal, it has been detected in the receiving water bodies. One of the major concerns is the promotion of antibiotic resistance, as well as its toxicity to aquatic organisms such as fish, invertebrates, and algae, and its ability to disrupt the natural microbial communities in water bodies. Moreover, water and wastewater treatment plants struggle to effectively treat water contaminated with amoxicillin. Consequently, new processes need to be explored to complement traditional water and wastewater treatments. Adsorption, being a relatively economical and simple technique, appears promising for this purpose. Numerous adsorbents are found in the literature to adsorb drugs, however, the fabrication of all these adsorbents involves various complex steps and substances when compared to the chitosan and alginate beads. Therefore, the objective of this study was to assess the adsorption of amoxicillin on chitosan and alginate beads. The optimal pH was found to be 4 for both beads. The kinetics study indicates that external diffusion governs adsorption for alginate, while internal diffusion governs adsorption for chitosan. Thermodynamic parameters demonstrated that adsorption is a spontaneous and endothermic process.\u003c/p\u003e","manuscriptTitle":"Adsorption of amoxicillin by chitosan and alginate biopolymers composite beads.","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-05-31 09:36:55","doi":"10.21203/rs.3.rs-4331760/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Major Revision","date":"2024-06-18T10:15:39+00:00","index":"","fulltext":""},{"type":"reviewerAgreed","content":"","date":"2024-05-21T00:00:28+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-05-20T23:18:40+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"Environmental Science and Pollution Research","date":"2024-05-20T21:17:06+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-05-03T04:58:18+00:00","index":"","fulltext":""},{"type":"submitted","content":"Environmental Science and Pollution Research","date":"2024-05-01T20:50:42+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"environmental-science-and-pollution-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"espr","sideBox":"Learn more about [Environmental Science and Pollution Research](https://www.springer.com/journal/11356)","snPcode":"11356","submissionUrl":"https://submission.nature.com/new-submission/11356/3","title":"Environmental Science and Pollution Research","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"79c9f37d-3a78-460d-908c-8af5cbf62279","owner":[],"postedDate":"May 31st, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2024-11-04T16:30:59+00:00","versionOfRecord":{"articleIdentity":"rs-4331760","link":"https://doi.org/10.1007/s11356-024-35293-4","journal":{"identity":"environmental-science-and-pollution-research","isVorOnly":false,"title":"Environmental Science and Pollution Research"},"publishedOn":"2024-10-28 16:21:51","publishedOnDateReadable":"October 28th, 2024"},"versionCreatedAt":"2024-05-31 09:36:55","video":"","vorDoi":"10.1007/s11356-024-35293-4","vorDoiUrl":"https://doi.org/10.1007/s11356-024-35293-4","workflowStages":[]},"version":"v1","identity":"rs-4331760","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4331760","identity":"rs-4331760","version":["v1"]},"buildId":"7rjqhiLT3MXkJMwkYKINL","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}