Recovery of Au(III) from electronic waste using solid phase extraction based on a magetic nanobiocomposite, OCBS@Fe3O4 @UiO-66-SH

Recovery of Au(III) from electronic waste using solid phase extraction based on a magetic nanobiocomposite, OCBS@Fe3O4 @UiO-66-SH | 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 Recovery of Au(III) from electronic waste using solid phase extraction based on a magetic nanobiocomposite, OCBS@Fe 3 O 4 @UiO-66-SH Parisa Poormoghadam, Soleiman Bahar, Yunes Naghdi This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6054990/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 28 May, 2025 Read the published version in Microchimica Acta → Version 1 posted 9 You are reading this latest preprint version Abstract This study created a zirconium-based MOF (UiO-66-NH 2 ) with thiol groups attached to its magnetic corn surface for adsorption and extraction of Au(III) from electronic waste. Characterization of the composite was verified using FTIR, XRD, FESEM, TGA and BET techniques. The temperature, adsorption period, and pH on Au(III) adsorption were investigated. The pH of solutions significantly impacts Au(III) adsorption, with pH 6.0 being the optimal value. The optimum Au(III) adsorption conditions were 50 ◦C, 40 min, and 10 mg of adsorbent. Moreover, functionalized oxidized magnetic corncobs with thiol (OCBS@Fe 3 O 4 @UiO-66-SH) showed a notable ability to adsorb Au(III) with a 1587 mg/g capacity. With mass ratios of Au(III) to competing ions (Mg, Mn, Cu, Zn, Co, Cd, and Ni) fixed at 1:1 or extended to 1:5, this adsorbent prefers Au(III) ions while showing negligible adsorption to other ions. The study validated a technique for extracting Au(III) from various electronic waste samples, achieving high recovery rates (95.30–104.75%), demonstrating its effectiveness and lack of matrix interference. Langmuir, Freundlich, and Temkin isotherm models were used to describe the adsorption process. Comparing models, the Langmuir model with the most excellent R 2 value is best for interpreting experimental adsorption data. Among three kinetic models, pseudo-first-order (PFO), pseudo-second-order (PSO) kinetic, and interparticle diffusion (ID) models, PFO model exhibited a high R 2 value (0.9976). Thermodynamic calculations reveal a positive Δ H °, indicating the endothermic process, and negative Δ G ° values representing spontaneous adsorption at 298–323 K. The positive Δ S ° shows that the adsorbed molecules are more uniformly dispersed on the surface, potentially enhancing the adsorption capacity. Au(III) Magnetic solid phase extraction Zirconium-based MOF Langmuir isotherm Figures Figure 1 Figure 2 Figure 3 Figure 4 Introduction Precious metals, known as PM, are used as catalysts, electrical conductors, and corrosion resistance agents due to their physical and chemical properties [ 1 ]. The electronics and catalyst sectors heavily rely on metals, accounting for over 90% of their usage and showcasing their significant importance. In electronics, gold and silver are chiefly used in manufacturing contacts, bonding wires, and switches of computers, mobile phones, video players, copiers, printers, microwave ovens, refrigerators, and freezers [ 2 ]. Recently, electronic waste (e-waste) production has significantly increased, mainly due to the disposal of electronic products at the end of their life span. E-waste is a crucial source of precious metals, yet only about 20% is recycled, highlighting significant gaps in resource recovery and sustainability efforts [ 3 ]. Gold, widely utilized in electronic devices for its outstanding corrosion resistance and high electrical conductivity, becomes a significant element of electronic waste (e-waste) following the disposal of these gadgets. E-waste contains approximately 6,800 tons of gold, 16% of global reserves, and 25 to 250 times the concentration in natural gold mines, varying from 1 to 10 grams per ton [ 4 ]. Retrieving gold from e-waste is seen as profitable and eco-friendly, offering economic, resource, and environmental benefits. Current gold recovery methods from electronic waste, mainly pyrometallurgical (energy-intensive) and hydrometallurgical (using aqua regia), lead to substantial pollution and are environmentally harmful. In contrast, using microorganisms that produce leaching substances for bioleaching offers an eco-sustainable method for extracting valuable metals from electronic waste [ 5 ]. It is critical to craft a technique for precisely separating and enriching Au(III) from diverse matrices before its instrumental evaluation. Historically, a variety of sample preparation methods, such as solvent extraction [ 6 ], cloud point extraction [ 7 ], and solid phase extraction [ 8 ], have been utilized to extract gold ions (Au(III)) from various matrices before analysis. Recent developments in sample preparation aim to simplify processes, reduce scale, automate, increase efficiency, and minimize solvent dependence. Different microextraction techniques have emerged, like liquid phase microextraction (LPME) and solid phase microextraction (SPME). SPME is particularly significant among microextraction techniques. Initially, SPME involved adsorbing target analytes from headspace or liquid samples onto a coated fiber, then desorption into a solvent. Magnetic solid-phase extraction (MSPE) proves beneficial in isolating Au(III) from electronic waste, employing magnetic adsorbents that specifically adhere to desired analytes, enabling straightforward separation via an external magnetic field. This technique reduces solvent use and hazardous waste, offering a greener alternative to conventional extraction methods. It involves customizable magnetic adsorbents that improve the selective extraction and enrichment of Au(III) and other precious metals [ 8 ]. Various adsorbents designed for environmental cleanup often face challenges like high costs and complex separation processes, limiting widespread use. So, the need for affordable, practical adsorbents has grown, with agricultural residues becoming valuable for creating cost-effective biosorbents due to their availability, low cost, and unique properties. In particular, corncobs, a residual product from corn processing, are often disposed of or burned, leading to environmental degradation without any positive gain [ 9 ]. Research has demonstrated that corncobs can be successfully used as starting materials in creating various products and activated carbon for water treatment, adsorption, biocatalysis, and hydrogen storage, underlining their potential for sustainable and practical applications. Corncobs, with their porous and fibrous nature, provide a high surface area and numerous binding sites, making them an excellent choice for adsorbent loading over non-biological substrates. They are cost-effective, widely available as an agricultural byproduct, and sustainable. Lignin and cellulose in corncobs strengthen their interaction with different adsorbents, improving their efficacy [ 10 ]. MOFs are materials defined by their distinctive lattice-like composition, which integrates metal ions bonded through organic bridging ligands, often containing elements like oxygen or nitrogen. The metal ions or clusters function within this structure as pivotal points, linked by stiff or semi-flexible organic ligands. MOFs are renowned for their extensive specific surface areas, high porosity, stability under heat, straightforward manufacturing, adjustable structures, and chemical adaptability [ 11 ]. They find utility in numerous domains, such as optics, catalysis, biosensing, medical imaging, and the separation and storage of gases. MOFs play a critical role in extracting and removing heavy metals because of their large surface area, tunable porosity, and functionalization capabilities, all of which increase their adsorption efficiency. Recent developments have shown that MOFs can effectively capture heavy metal ions from water, allowing for proactive water quality management and real-time monitoring [ 12 ]. Many MOFs demonstrate remarkable selectivity for specific heavy metal ions owing to their customizable pore shapes and functional groups. MOFs may be functionalized to improve their ability to remove metal by adding certain functional groups that allow for more selective binding to target metal ions. Functional groups such as sulfonyl, amide, sulfur, and nitrogen significantly enhance the adsorption capacity of MOFs for heavy metals [ 13 ]. UiO-66-NH 2 is a metal-organic framework (MOF) that has amino groups (-NH 2 ) integrated into its structure and is based on an octahedral cluster of zirconium that is linked by terephthalate linkers. UiO-66-NH 2 establishes strong interactions with analytes, including metal ions, through the amino groups present in the linkers [ 14 ]. Its exceptional thermal and chemical stability, robust coordination bonds, high connectivity, and adjustable pore dimensions make it ideal for selective adsorption and effective separation of metal ions from complex mixtures, with covalent integration of specific functional groups improving its metal ion adsorption capacity and selectivity. UiO-66-NH 2 exhibits considerable adsorption capabilities for a range of metal ions, encompassing Pb(II), Cd(II), Cr(VI), and Au(III), along with notable removal efficiencies achieved within brief contact durations [ 15 ]. According to the hard-soft-acid-base (HSAB) theory, Au(III) ions, classified as soft acids, tend to be selectively bonded by soft Lewis bases, particularly those with sulfur and nitrogen, through various bonding methods, including ion-exchange, electrostatic, and chelation interactions [ 16 ]. Studies have shown that thiol-functionalized Zr-based MOFs exhibit good efficiency and selectivity for the extraction of Au(III) ions from aqueous samples as well as complex matrices. Therefore, in this work, we utilized thiol-functionalized UiO-66-NH 2 (Zr-based MOF) to fabricate a magnetic bioadsorbent in order to present an adsorbent with high adsorption capacity for Au(III) ions. In this study, a zirconium-based MOF (UiO-66-NH 2 ) modified with thiol groups on the surface of oxidized magnetic corncobs (OCBS@Fe 3 O 4 @UiO-66-SH) was synthesized for the adsorption and extraction of Au(III) from electronic waste. The OCBS@Fe 3 O 4 @UiO-66-SH was characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA), and Brunauer-Emmett-Teller (BET) techniques. The extraction system, comprising the magnetic adsorbent, was actively stirred on a magnetic stirrer to ensure uniform mixing and interaction within the sample. After completing the process and Au(III) desorption from the adsorbent, Au(III) concentration was determined using a flame atomic absorption spectrometer. The study further explored the influence of various parameters on the adsorbent’s efficacy for Au(III) recovery, including sample volume, washing solvent type, and washing solvent volume. Materials and methods Chemical and reagents The materials used in this work include acetic acid with a purity of 99.8%, TEMPO with a purity of 98%, sodium hydroxide with a purity of 98%, N,N-dimethylformamide with a purity of 99.8%, and sodium bromide with a purity of 99% were purchased from Merck. Sodium chlorite with a purity of 80%, sodium hypochlorite with a concentration of 10–15% available chlorine, ferrous sulfate heptahydrate with a purity of 99%, ferric chloride hexahydrate with a purity of 97%, toluene with a purity of 99.8%, chloroacetyl chloride with a purity of 98%, triethylamine with a purity of 99%, zirconium(IV) chloride with a purity of 99.5% and sodium sulfide with a purity of 98% were obtained from Sigma-Aldrich. Other materials are 2-amino terephthalic acid with a purity of 99% (TCI Chemicals), hydrochloric acid with a concentration of 37% (Fisher Scientific), and nitric acid with a concentration of 70% (Fisher Scientific). The devices used include a heating apparatus (IKA C-MAG HS 7), ultrasonic bath (Branson 5800), magnetic stirrer (IKA C-MAG HS 7), and oven 50 (Fur, Behdad, Iran). Delignification and TEMPO oxidation of corncobs The preparation steps of OCBs, OCBs-Fe 3 O 4 , OCBS@Fe 3 O 4 @UiO-66-NH 2 and OCBS@Fe 3 O 4 @UiO-66-SH nanocomposites are shown schematically in Scheme 1 . Sodium chlorite was used for delignification of corn, which is usually used for this purpose. For this mean, 10 g of oven-dried corn was added in 700 mL of a solution comprising 7 g of sodium chlorite and 3 mL of acetic acid, heated to 80°C for three hours. The processed corn, named delignification corncobs (DCBs), underwent washing with distilled water to attain a neutral pH level. Following this, TEMPO oxidation was applied to the DCBs, adhering to a technique noted in the literature [ 17 ]. In this phase, 10 g of DCBs was merged with a 400 mL solution infused with 0.1 g of TEMPO. Sequentially, 1 g of NaBr and 30 mL of NaClO solution were incorporated under constant stirring, with the reaction sustained for four hours at a pH close to 10. Subsequently, the oxidized product, oxidized corncobs (OCBs), was cleansed using deionized water to neutralize the pH and then secured in a sealed bag in a refrigerator. Preparation of OCBs-FeO nanocomposite During the typical procedure, 1 g of OCBs were ultrasonically treated in 15 mL of distilled water for 15 minutes to achieve dispersion. Following this, 80 mL of an aqueous solution containing 0.556 g of FeSO 4 .4H 2 O and 1.081 g of FeCl 3 .6H 2 O was incrementally introduced to the dispersed OCBs, and the mixture temperature was raised to 40°C. A few NaOH drops were added to bring the pH level to 10. At 80°C, the mixture was stirred for 30 minutes without interruption. The OCBs@Fe 3 O 4 nanocomposite cooled to ambient temperature was rinsed three times with distilled water and then dried at 80°C under vacuum. Preparation of OCBS@FeO@UiO-66-NH To synthesize OCBS@Fe 3 O 4 @UiO-66-NH 2 , 1 g of the OCBs@Fe 3 O 4 was dispersed in 45 mL of a solution containing 0.1125 g of ZrCl 4 in DMF (solution A). This mixture was then stirred for 10 minutes. Then, 0.0797 g of 2-amino acids were carefully mixed into Solution A, stirring the blend for 5 minutes. After that, it was placed in an autoclave lined with Teflon and heated to 120°C for one day. Subsequently, the resulting solid product underwent thorough rinsing with water and ethanol. The OCBS@Fe 3 O 4 @UiO-66-NH 2 composite was vacuum-dried at 70°C for 12 hours. Preparation of OCBS@FeO@UiO-66-SH 15 mL of toluene was added to a mixture containing 1 g of OCBS@Fe 3 O 4 @UiO-66-NH 2 . Ultrasonic waves were used to treat for half an hour. Next 1.01 mL of triethylamine and 0.3164 g of 2-chloroacetyl chloride were added to the mixture, which was then agitated with a stirrer for 12 hours at room temperature. The resulting mixture was washed thrice with toluene and twice with methanol and then left to air dry at room temperature. Then, 1 g of the product obtained was mixed, with a solution of Na 2 S by dissolving 2 g of Na 2 S in 30 mL of DMF. The combined solution was then heated under reflux at 150°C for twelve hours. The solid product was separated using magnets. Rinsed with DMF. After vacuum drying at 60°C for twelve hours, the final product was obtained as OCBS@Fe 3 O 4 @UiO-66-SH. Extraction of Au(III) from electronic waste The process commenced with the thermal decomposition of the scrap to break down its components. Subsequently, silver was extracted by washing it at 40°C using 50 mL of HNO 3 , producing silver nitrate (AgNO 3 ) as a byproduct. The remaining materials then underwent a process involving the washing of Au(III) using aqua regia, an HCl:HNO 3 solution (3:1), at 40°C, followed by the disposal of solid waste. Finally, Au(III) was extracted from the resulting solution using OCBS@Fe 3 O 4 @UiO-66-SH, leading to wastewater generation (Scheme 2 ). Au(III) adsorption measurement OCBS@Fe 3 O 4 @UiO-66-SH was employed as an adsorbent to measure the adsorption of Au(III) in a room-temperature environment. Initially, 30 mL of a 400 mg/L Au(III) solution was combined with 10 mg of OCBS@Fe 3 O 4 @UiO-66-SH. The mixture was stirred at 300 rpm for 40 minutes. The impact of pH on Au(III) adsorption was investigated within the pH range of 2 to 12, and the pH levels were adjusted using hydrochloric acid and sodium hydroxide solutions. The desorption process was carried out with thiourea for 20 minutes. Subsequently, deionized water was used to wash the adsorbent. Following this, flame atomic absorption spectrometry was utilized to analyze the residual Au(III) content in the solution, aiming to evaluate the effectiveness of the adsorption process. In this waste study, a mix of 30 mL of Au(III) solution extracted from waste and 10 mg of the adsorbent material were combined in a beaker (50 mL) at pH level 6 and room temperature. The mixture underwent stirring for 40 minutes. Equations 1 and 2 were used to determine the removal percentage (R%) and adsorption capacity ( q e , mg/g) of Au(III) ions: $$\:{\:q}_{e}=\frac{({C}_{0}-{C}_{e})V}{m}$$ 1 $$\:R=\frac{{C}_{0}-{C}_{e}}{{C}_{0}}\times\:100$$ 2 where C 0 (mg/L) is the initial concentration of the adsorbate in the solution, C e (mg/L) is the equilibrium concentration of the adsorbate after the adsorption process, V (mL) is the volume of the solution, and m (mg) is the mass of the OCBS@Fe 3 O 4 @UiO-66-SH . Results and discussion Characterization Figure 1 a displays the FT-IR spectra of OCBs@Fe 3 O 4 , OCBs@Fe 3 O 4 @UiO-66-NH 2 , OCBs@Fe 3 O 4 @UiO-66-SH, and UiO-66-NH 2 . Two absorption peaks at 3461 cm − 1 and 3361 cm − 1 in the FT-IR spectra of UiO-66-NH 2 are attributed to the symmetric and asymmetric N-H stretching vibrations of the primary amine (-NH 2 ) functional group that is present in the 2-amino terephthalate linker [ 18 ]. The 1650 cm − 1 and 1482 cm − 1 peaks indicate the C = O stretching vibration of the carboxylate group (-COO-) and the N-H bending vibration of the -NH 2 group in the amino terephthalate linker. The highest peak at 1382 cm − 1 is probably attributable to the bending vibrations of the C-N bond, and peaks appearing at about 750 cm − 1 are attributed to the Zr-O vibrations [ 19 ]. Differences can be seen in the upward shift for the carbonyl peak from 1645 cm − 1 in OCBs@Fe 3 O 4 @UiO-66-NH 2 to 1680 cm − 1 in OCBs@Fe 3 O 4 @UiO-66-SH. Moreover, two peaks associated with C-S and S-H bonds appeared. In the FT-IR spectrum of OCBs@Fe 3 O 4 @UiO-66-SH, the vibrations related to Zr-O stretching due to µ 3 -OH groups in the framework are around 700 cm − 1 . A µ 3 -OH group is a bridging hydroxo group where a hydroxyl group (OH) bridges three metal atoms (in this case, Zr atoms) [ 20 ]. Stretching modes of S-H and C-S are noticed at 2550 cm − 1 and 1200 cm − 1 , respectively. Moreover, the C-O stretching vibrations of the cellulose and hemicellulose of OCBs are responsible for the peak at 1200 cm − 1 . After S-H is functionalized in MOF, the peak at 1650 cm − 1 changes to 1680 cm − 1 , showing that post-synthetic modification of amine-functionalized UiO-66-NH 2 has integrated thiol groups into the structure [ 21 ]. An intense and broad peak in the 3300–3400 cm − 1 range indicates that the O–H bonds in the glucose units of starch inside OCBs are expanding. Peaks in the range of 900–1200 cm − 1 , with a peak close to 1000 cm − 1 , are associated with the stretching vibrations of glucose molecules’ C–O–C bonds. The noticeable peak at 580–590 cm − 1 is associated with Fe–O stretching vibrations in the Fe 3 O 4 magnetite structure. In OCBs@Fe 3 O 4 spectrum, peaks detected at 1612 cm − 1 and 565 cm − 1 validate the existence of C–O and Fe–O vibrations. The XRD patterns of OCBs@Fe 3 O 4 , OCBs@Fe 3 O 4 @UiO-66-NH 2 , OCBs@Fe 3 O 4 @UiO-66-SH, and UiO-66-NH 2 are presented in Fig. 1 b. The XRD pattern of the UiO-66-NH 2 material shows peaks at 2𝜃= 7.2°, 8.1°, and 25.0° representing the crystal planes (111), (200) and (731), respectively, indicating its nature and successful creation. The composite of OCBs@Fe 3 O 4 peaks at around 15°, 16°, and 22.5°, signifying the corncob cellulose structure within it [ 22 ]. Diffraction peaks at angles of 31°, 34°, 43°, 52°, 57°, and 62°, which correlate to the Miller indices of (220), (311), (400), (422), (511), and (440), are seen to establish the existence of the magnetite Fe 3 O 4 phase. Additionally, distinct peaks characteristic of UiO-66-NH 2 and OCBs@Fe 3 O 4 are also noted in the OCBS@Fe 3 O 4 @UiO-66-NH 2 material, indicating the synthesis of all components into a nanocomposite. The XRD patterns for OCBS@Fe 3 O 4 @UiO-66-NH 2 and OCBS@Fe 3 O 4 @UiO-66-SH show similarities, with variations noted between them. The SEM images of OCBs-Fe 3 O 4 and OCBS@Fe 3 O 4 @UiO-66-SH are presented in the Fig. 2 . The SEM image of OCBs@Fe 3 O 4 (Fig. 2 (A)) reveals a porous structure composed of numerous small, spherical particles. The bright spots are likely Fe 3 O 4 nanoparticles deposited on the surface of the OCBS [ 23 ]. The underlying substrate appears irregular and porous, which can be attributed to the carbon material derived from OCBS. As evident, the surface of the OCBS-derived carbon acts as a high surface area substrate for loading Fe 3 O 4 nanoparticles, thereby preventing their aggregation to some extent. The SEM image of OCBS@Fe 3 O 4 @UiO-66-SH (Fig. 2 (B)) depicts a 3D porous structure containing particles with irregular shapes and sizes. The rough and textured surface, with small protrusions and cavities, is characteristic of MOFs like UiO-66, and the surface roughness indicates functionalization with thiol groups. Based on this SEM image, it appears that the magnetic Fe 3 O 4 nanoparticles are well-loaded within and between the MOF particles and on the surface of the OCBS-derived carbon [ 24 ]. Figure S1 shows the TGA curves of UiO-66-NH 2 and OCBS@Fe 3 O 4 @UiO-66-SH. The moisture in the sample causes weight loss of about 10% at temperatures between 20°C and 131°C. A 5% reduction in temperature at 281°C may result from the depletion of surface groups or organic compounds, including ligands or functional groups. The 39% reduction at 675°C is presumably attributable to the disintegration of the primary MOF structure, resulting in the framework's collapse and subsequent loss of the composite [ 25 , 26 ]. In contrast, in OCBs@Fe 3 O 4 @UiO-66-SH nanocomposite, the loss weights after raising the temperature to 131°C, 281°C, and 675°C are 3%, 7% and 52%, respectively. The first 3% weight reduction at 131°C signifies the expulsion of moisture or low-molecular-weight substances. The 7% weight reduction at 281°C is ascribed to the breakdown of organic constituents or partial disintegration of the composite. The significant weight reduction of 52% at 675°C signifies considerable thermal deterioration, presumably resulting from the disintegration of the UiO-66 framework, highlighting the thermal constraints of the composite. The TGA curves represent that the weight loss in UiO-66-NH 2 occurs at a lower temperature range compared to the OCBs@Fe 3 O 4 @UiO-66-SH composite, indicating that the incorporation of OCBs and Fe 3 O 4 nanoparticles into the UiO-66-SH framework enhances its thermal stability [ 27 ]. It is observed that, after the temperature of 600°C, the weight loss of OCBS@Fe 3 O 4 @UiO-66-SH is higher because, at this temperature, corn also decomposes at a high rate. According to literature, corncob begins to decompose at 210°C and decomposes entirely around 600°C. In this work, due to the strong interaction between corncob and the components (UiO-66-SH and Fe 3 O 4 ), the stability of the corn also increases, and it begins to degrade at higher temperatures. The BET analysis was performed for Fe 3 O 4 @UiO-66-SH and OCBS@Fe 3 O 4 @UiO-66-SH, the results are presented in Table 1 . Table 1 BET analysis results of Fe 3 O 4 @UiO-66-SH and OCBs@Fe 3 O 4 @UiO-66-SH V m (cm 3 /g) a s,BET (m 2 /g) V p,T (P/P 0 = 0.990) (cm 3 /g) d p,m (nm) Fe 3 O 4 @UiO-66-SH 1.5841 66.6428 0.019642 11.396 OCBs@Fe 3 O 4 @UiO-66-SH 1.7735 84.5466 0.020234 10.485 The BET analysis results for Fe 3 O 4 @UiO-66-SH and OCBs@Fe 3 O 4 @UiO-66-SH reveal key differences in their surface area and porosity characteristics. Fe 3 O 4 @UiO-66-SH exhibited a monolayer adsorption capacity (V m ) of 1.5841 cm 3 /g, a specific surface area (a s,BET ) of 66.6428 m²/g, a total pore volume (V p,T ) of 0.019642 cm 3 /g, and an average pore diameter (d p,m ) of 11.396 nm. In comparison, OCBs@Fe 3 O 4 @UiO-66-SH demonstrated a higher V m of 1.7735 cm 3 /g, a more significant a s,BET of 84.5466 m²/g, a slightly larger V p,T of 0.020234 cm³/g, but a smaller d p,m of 10.485 nm. These findings highlight the impact of OCBs incorporation on the material’s adsorption properties, suggesting potential advantages in applications where higher surface area and specific pore size distributions are desired. Optimization study of operating conditions The effect of pH on Au(III) adsorption The Fig. 3 a illustrates how much Au(III) (mg/g) was adsorbed on OCBs@Fe 3 O 4 @UiO-66-SH composite at different pH values. At low pH (2–4), some functional groups (eg, -SH and -COOH) on the surface of composites may be protonated, and the binding sites for Au(III) can be significantly reduced. The apparent increase in the adsorption capacity is observed from pH 4 to 6, and the maximum is seen at around pH 6. At very low pH, H + ions may compete with Au(III) for binding sites, diminishing adsorption efficacy. Still, at elevated pH, Au(III) are likely to transform into gold hydroxides and precipitate, rendering them less accessible for adsorption. At pH 6, a balance exists between the stability and availability of Au(III) species in solution and the functional groups on the composite that are accessible for binding. Furthermore, the -SH groups get protonated in lower pH circumstances (more acidic), diminishing their affinity for Au(III). Conversely, at elevated pH levels (more alkaline circumstances), the -SH and -COOH functional groups deprotonate, resulting in a negatively charged surface that induces electrostatic repulsion with the anionic Au(III) species [ 28 ]. The effect of time on Au(III) adsorption Figure 3 b depicts the adsorption capacity of Au(III) onto an OCBS@Fe 3 O 4 @UiO-66-SH composite in 10–45 minutes at room temperature. It is evident that the adsorption capacity increases rapidly and this increase continues until 30 minutes. From 30 to 40 minutes, the adsorption capacity reaches saturation and does not show much change, so that after 40 minutes it reaches a constant value. This shows that at 40 minutes the adsorption capacity of the adsorbent reaches its maximum value and more time has no effect on increasing the adsorption capacity [ 29 ]. The effect of temperature on Au(III) adsorption Figure 3 c shows that the adsorption capacity of OCBS@Fe 3 O 4 @UiO-66-SH composite material for Au(III) increases with increasing temperature from 25°C to 50°C. This trend can occur for several reasons. The first reason is that as the temperature increases, the kinetic energy of Au(III) or particles also increases, resulting in higher mobility of Au(III) and more adsorbing on the adsorption site, leading to better adsorbing effect and higher adsorption capacity. The second reason is that higher temperatures will increase the mass transfer of Au(III) from bulk solution into or onto the composite material surface, which is the way that higher temperatures increase the motion and diffusion of Au(III) into the adsorbent surface. The Au(III) adsorption on composite is likely an endothermic process, meaning that higher temperatures increase the activation energy needed for Au(III) species to overcome the energy barrier for attaching to the adsorption sites [ 30 ]. The effect of concentration on Au(III) adsorption Figure 3 d shows the results of an investigation into the impact of increasing the concentration of Au(III) from 100 mg/L to 900 mg/L on its absorption by OCBS@Fe 3 O 4 @UiO-66-SH composite. It is evident that as the initial concentration of Au(III) grows, so does the composite's adsorption capability. This is because there are enough adsorption sites on the composite surface at lower concentrations, and raising the concentration of Au(III) is likely to increase the number of Au(III) ions that can be adsorbed to the available adsorption sites, thereby increasing the adsorption capacity [ 31 ]. On the other hand, because all adsorption sites accessible at lower concentrations are occupied, the available adsorption sites are likely to be saturated when the concentration is raised. Therefore, increasing the Au(III) concentration hardly helps to improve the adsorption capacity, which is why the absorption curve decreases at high concentrations The high surface area, porosity, and binding groups of UiO-66 MOF provide many adsorption species at the particle surface. In contrast, the thiol functional group (-SH) provides a strong affinity for Au(III) binding [ 32 ]. The quantity of absorption capacity found in this investigation demonstrated that the amount of absorption rises with concentration. It is also evident from Table S1 that the OCBs@Fe 3 O 4 @UiO-66-SH have an adsorption capacity that is within the literature limit and, in some instances, more excellent for Au(III) in solution. The adsorption capacity of several adsorbents reported for Au(III) adsorption in the literature is also shown in Table S1 . Our proposed adsorbent shows a competitive adsorption capacity (1587 mg/g) under the following conditions: 10 mg adsorbent, volume of Au(III) solution 30 mL, pH 6, and temperature 50°C. As can be seen, our adsorbent has a higher adsorption capacity than the polymer containing N (based on MOP) (1073 mg/g) [ 33 ], CoFe 2 O 4 @S-CoWO 4 (1049 mg/g) [ 34 ] and M-Cu-BDC-NH 2 (1184 mg/g) [ 35 ]. Our OCBS@Fe 3 O 4 @UiO-66-SH adsorbent shows competitive performance in adsorption capacity, works at near-neutral pH, and reaches equilibrium relatively quickly, indicating that it can be a promising material for Au(III) adsorption applications. Isotherm models as well as kinetic models were used to investigate the mechanism and rate of adsorption, the results of which are presented in the supporting information file. Adsorption selectivity Because e-waste contains many metal ions, the solution’s composition is complex, which leads to a high degree of competitive adsorption ions. Thus, evaluating Au(III)’s adsorption selectivity is crucial. As Fig. 4 illustrates, there is negligible adsorption of Mg, Mn, Cu, Zn, Co, Cd, Ni, and OCBS@Fe 3 O 4 @UiO-66-SH exclusively catch Au(III) when the mass ratios of Au(III) to competing ions are set at 1:1 and even extended to 1:5. As can be seen, the q e value for Au(III) is about 550 mg/g for both ratios, which is significantly higher than any other metal. This indicates that the extraction method used is highly selective for Au(III), even in the presence of several different metals. For intervening metals, the extraction efficiency is much lower and below 50 mg/g. Cu, with a q e value of about 30 mg/g in 1:1 conditions and a little less in 1:5 conditions, shows the highest extraction among the intervening metals. Other metals, such as Fe and Mn have low extraction efficiency (below 20 mg/g). It is interesting to note that the ratio of Au(III) to interfering metals does not have a significant effect on Au(III) extraction efficiency. However, for some interfering metals such as Cu and Co, the extraction efficiency is slightly higher in the 1:1 condition than in the 1:5 condition. As a result, the extraction method used is highly selective for Au(III) and achieves excellent separation from other metals usually found in complex mixtures. Thus, our findings demonstrate that OCBS@Fe 3 O 4 @UiO-66-SH has exceptional selectivity in differentiating Au(III) from other coexisting interfering metals. Adsorption kinetic and thermodynamic parameters In the continuation of this work, the adsorption process model and its kinetic and thermodynamic studies were also investigated, the results of which are provided as a file in the supplementary information section. Analysis of real sample Validation of the suggested technique for extracting Au(III) was conducted on calculator scrap, PC board scrap, mobile phone scrap and PC mainboard scrap, and the findings are shown in Table 2 . The conventional standard addition method was used to quantify the content of Au(III) in electronic waste samples. To examine the recovery of Au(III), a standard solution containing Au(III) at two different concentrations (20 and 40 mg/L) was introduced into the extracted Au(III) samples. The amount of Au(III) found in the calculator scrap, PC board scrap, mobile phone scrap, and PC mainboard scrap samples were 107.03, 125.90, 157.98, and 205.15 ppm, respectively. Moreover, the recovery rates for the spiked samples ranged from 95.30–104.75%. The achieved recoveries within the 95.30–104.75% range, indicating impressive concordance between the spiking and extracted levels. The recovery of Au(III) was successful, and the productivity of Au(III) extraction was not influenced by the matrix of the three electronic waste samples. Table 2 Determination of Au(III) in electronic waste samples Amount of Au(III) (ppm) Sample Added Found Recovery (%) Calculater scrap 0 107.03 20 127.40 101.85 40 145.60 96.40 PC board scrap 0 125.90 20 144.96 95.30 40 167.20 103.25 Mobile phone scrap 0 157.98 20 178.80 104.10 40 196.80 97.05 0 205.15 PC mainboard scrap 20 226.10 104.75 40 245.40 100.62 Conclusion This work introduced a novel adsorbent based on corncob (OCBS@Fe 3 O 4 @UiO-66-SH) to extract Au(III) from real samples efficiently. Characterization of composite with FT-IR, XRD, FESEM, BET, and TGA analysis proved that this adsorbent is synthesized successfully. The effects of pH, time, and temperature. Examining the impact of pH in the range of pH 2.0 to 12.0 on the absorption of Au(III) showed the maximum absorption capacity around pH 6. Moreover, the adsorption capacity rises up to 40 minutes with the adsorbent, implying that all active sites are occupied and the system is in equilibrium. After 40 minutes, the capacity does not vary substantially. Additionally, the absorption capacity of the OCBS@Fe 3 O 4 @UiO-66-SH composite material for Au(III) increases as the temperature rises from 25°C to 50°C. Our findings demonstrated that OCBS@Fe 3 O 4 @UiO-66-SH has exceptional selectivity in differentiating Au(III) from other coexisting interfering metals (Mg, Mn, Cu, Zn, Co, Cd, Ni). The study validated a technique for extracting Au(III) from various electronic waste samples, including calculator scrap, PC board scrap, mobile phone scrap, and PC mainboard scrap. The recovery rates ranged from 95.30–104.75%, demonstrating the technique’s effectiveness regardless of the electronic waste source. The results of data fitting with different isotherm models showed that the Langmuir model, with the highest R 2 value, is the most suitable model for interpreting experimental data. This evidence indicates that the adsorption mechanism is monolayer, and the adsorption process proceeds with minimal interaction between the adsorbed molecules. The kinetics are primarily governed by the interaction of the adsorbent molecules with surface sites, which is consistent with the fundamental ideas of the PFO model, as shown by the excellent agreement between the calculated and observed qe values and the high R 2 value. Thermodynamic studies revealed that the spontaneous adsorption process is represented by the negative Δ G ° values obtained in the temperature range of 298 to 323 K, and the positive adsorption enthalpy value shows the heat of the surface adsorption process. Furthermore, the system’s degree of disorder increases, as demonstrated by the positive Δ S ° (13.52 J/mol·K), implying that the adsorbed molecules are more uniformly dispersed on the surface, potentially enhancing the adsorption capacity. Declarations Funding This work was supported by the University of Kurdistan (No. 9813008101). Author Contribution Parisa Poormoghadem and Soleiman Bahar made substantial contribution to the conception or design of the work; or the acquisition, analysis, or interpretation of data used in the work; and also Yones Naghdi contributions to the synthesis of adsorbent. References Zientek ML, Loferski PJ (2014) Platinum-Group Elements - So Many Excellent Properties. Fact Sheet pp. 2014 – 3064. https://doi.org/10.3133/fs20143064 Ilyas S, Srivastava RR, Kim H (2021) O 2 -enriched microbial activity with pH-sensitive solvo-chemical and electro-chlorination strategy to reclaim critical metals from the hazardous waste printed circuit boards. 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Phys Chem Chem Phys 17:117–121. 10.1039/C4CP04162C Zhang X, Zhang Y, Wang T et al (2019) A thin film nanocomposite membrane with pre-immobilized UiO-66-NH 2 toward enhanced nanofiltration performance. RSC Adv 9:24802–24810. 10.1039/C9RA04714J Cirujano FG, Llabrés i Xamena FX (2020) Tuning the Catalytic Properties of UiO-66 Metal–Organic Frameworks: From Lewis to Defect-Induced Brønsted Acidity. J Phys Chem Lett 11:4879–4890. https://doi.org/10.1021/acs.jpclett.0c00984 Kuypers S, Pramanik SK, D’Olieslaeger L et al (2015) Interfacial thiol–isocyanate reactions for functional nanocarriers: a facile route towards tunable morphologies and hydrophilic payload encapsulation. Chem Commun 51:15858–15861. 10.1039/C5CC05258K Yuan M, Wang Z, Liu Y, Yang G (2021) Fabrication of Magnetic Catalyst Fe 3 O 4 -SiO 2 -V3 and Its Application on Lignin Extraction from Corncob in Deep Eutectic Solvent. Polym (Basel) 13:1545. https://doi.org/10.3390/polym13101545 Bagherzadeh M, Aslibeiki B, Arsalani N (2023) Preparation of Fe 3 O 4 /vine shoots derived activated carbon nanocomposite for improved removal of Cr (VI) from aqueous solutions. Sci Rep 13:3960–3978. https://doi.org/10.1038/s41598-023-31015-x Chowdhury S, Sharma P, Rathi P, Siril PF (2022) Direct One-pot Synthesis of Highly Tunable Mixed-linker UiO-66-(SH) 2 Metal-Organic Frameworks: Enroute Toward Robust Sulfonic Acid Tagged UiO-66 Architectures. 10.26434/chemrxiv-2022-35rk2 Athar M, Rzepka P, Thoeny D et al (2021) Thermal degradation of defective high-surface-area UiO-66 in different gaseous environments. RSC Adv 11:38849–38855. 10.1039/D1RA05411B Wang Y, Luo Y, Wang L (2024) Characterization and performance investigation of UiO-66 for low-grade thermochemical adsorption heat storage. Microporous Mesoporous Mater 366:112918. https://doi.org/10.1016/j.micromeso.2023.112918 Kazemi A, Moghadaskhou F, Pordsari MA et al (2023) Enhanced CO 2 capture potential of UiO-66-NH 2 synthesized by sonochemical method: experimental findings and performance evaluation. Sci Rep 13:19891. https://doi.org/10.1038/s41598-023-47221-6 Viltres H, López YC, Gupta NK et al (2022) Functional metal-organic frameworks for metal removal from aqueous solutions. Sep Purif Rev 51:78–99. https://doi.org/10.1080/15422119.2020.1839909 Rápó E, Tonk S (2021) Factors affecting synthetic dye adsorption; desorption studies: a review of results from the last five years (2017–2021). Molecules 26:5419. https://doi.org/10.3390/molecules26175419 Tang J, Chen Y, Wang S, Zhang L (2021) Engineering of UiO-66-NH 2 as selective and reusable adsorbent to enhance the removal of Au (III) from water: Kinetics, isotherm and thermodynamics. J Colloid Interface Sci 601:272–282. https://doi.org/10.1016/j.jcis.2021.05.121 Rajabi M, Keihankhadiv S, Suhas et al (2023) Comparison and interpretation of isotherm models for the adsorption of dyes, proteins, antibiotics, pesticides and heavy metal ions on different nanomaterials and non-nano materials—a comprehensive review. J Nanostructure Chem 13:43–65. https://doi.org/10.1007/s40097-022-00509-x Aghaei E, Alorro RD, Encila AN, Yoo K (2017) Magnetic adsorbents for the recovery of precious metals from leach solutions and wastewater. Met (Basel) 7:759–790. https://doi.org/10.3390/met7120529 Zhou S, Xu W, Hu C et al (2020) Fast and effective recovery of Au (III) from aqueous solution by a N-containing polymer. Chemosphere 260:127615. https://doi.org/10.1016/j.chemosphere.2020.127615 Zhao M, Zhang Y, Yang R et al (2023) Construction of Magnetic S-Doped CoWO 4 Composite for Efficient and Selective Recovery of Gold from Wastewater via Adsorption–Reduction Pathway. Small Struct 4:2300039. https://doi.org/10.1002/sstr.202300039 Xiang Y, Cheng C-Y, Liu M-H et al (2024) Efficient recovery of gold using Macroporous Metal-Organic framework prepared by the’MOF in MOF’method. Sep Purif Technol 335:126131. https://doi.org/10.1016/j.seppur.2023.126131 Additional Declarations No competing interests reported. Supplementary Files Supportinginformation.docx GA.docx Schemes.docx Cite Share Download PDF Status: Published Journal Publication published 28 May, 2025 Read the published version in Microchimica Acta → Version 1 posted Editorial decision: Revision requested 12 Mar, 2025 Reviews received at journal 11 Mar, 2025 Reviews received at journal 06 Mar, 2025 Reviewers agreed at journal 26 Feb, 2025 Reviewers agreed at journal 23 Feb, 2025 Reviewers invited by journal 23 Feb, 2025 Editor assigned by journal 19 Feb, 2025 Submission checks completed at journal 19 Feb, 2025 First submitted to journal 18 Feb, 2025 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. 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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-6054990","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":417922185,"identity":"436bb68a-59e7-463e-85c2-75d030844e89","order_by":0,"name":"Parisa Poormoghadam","email":"","orcid":"","institution":"University of Kurdistan","correspondingAuthor":false,"prefix":"","firstName":"Parisa","middleName":"","lastName":"Poormoghadam","suffix":""},{"id":417922186,"identity":"8fa7cb0f-08c1-480c-b9be-bc97a6156075","order_by":1,"name":"Soleiman Bahar","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAwklEQVRIiWNgGAWjYFACHgZmICnHwMAG5RKrxZh0LYkNUC2EgXwD78HPBTX30jccb0tg+FHDIGPeQECLwQG+ZOkZx4pzN5w5doCx5xgDj8wBQloYeAykedgScjfcSG9g4G1g4JEg7DAe4988/xLSDYBaGP8So4XhAI+ZNG9bQoLBjbQDzETZYnCYL82aty/BcOaZYwmHZY5JEOGw9t7Dt3m+JcjzHW8zfPimxsaesMOYkR3JwEBYwygYBaNgFIwCIgAAT6s1mMVBj2EAAAAASUVORK5CYII=","orcid":"","institution":"University of Kurdistan","correspondingAuthor":true,"prefix":"","firstName":"Soleiman","middleName":"","lastName":"Bahar","suffix":""},{"id":417922188,"identity":"4168d576-7b44-4aa1-9021-bd51028d3897","order_by":2,"name":"Yunes Naghdi","email":"","orcid":"","institution":"University of Kurdistan","correspondingAuthor":false,"prefix":"","firstName":"Yunes","middleName":"","lastName":"Naghdi","suffix":""}],"badges":[],"createdAt":"2025-02-18 09:53:35","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6054990/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6054990/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s00604-025-07247-1","type":"published","date":"2025-05-28T15:57:47+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":76826895,"identity":"0f04765b-17e6-4efc-a5e1-9525261c7f2a","added_by":"auto","created_at":"2025-02-21 07:44:15","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":194543,"visible":true,"origin":"","legend":"\u003cp\u003ea) FT-IR spectra and b) XRD patterns of OCBs@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e,\u003csub\u003e \u003c/sub\u003eOCBs@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-NH\u003csub\u003e2\u003c/sub\u003e, OCBs@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-SH\u003csub\u003e \u003c/sub\u003eand UiO-66-NH\u003csub\u003e2\u003c/sub\u003e\u0026nbsp; \u003csub\u003e\u0026nbsp;\u003c/sub\u003e\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-6054990/v1/592b5ab683b9b767ae3db32a.png"},{"id":76825604,"identity":"b10ed4b2-b2d1-4305-b38b-ea0ac0591a2a","added_by":"auto","created_at":"2025-02-21 07:36:14","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":511525,"visible":true,"origin":"","legend":"\u003cp\u003eSEM images of A) OCBs@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4 \u003c/sub\u003eand B) OCBS@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-SH\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-6054990/v1/5a024540b32006c07481b2cf.png"},{"id":76825130,"identity":"2b7cff6e-8920-45cc-a81e-e78bd6633df5","added_by":"auto","created_at":"2025-02-21 07:28:14","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":66403,"visible":true,"origin":"","legend":"\u003cp\u003eInfluences of pH (CAu(III) = \u0026nbsp;300 mg/L(30 mL); madsorbent = 10 mg; time = 20 min; T = 25), b) time (CAu(III) = \u0026nbsp;300 mg/L 30 mL); madsorbent = 10 mg; pH= 6; T = 25), c)temperature (CAu(III) = \u0026nbsp;300 mg/L (30 mL); madsorbent = 10 mg; pH= 6; time = 40 min) and d) initial Au(III) concentration (madsorbent = 10 mg; solution volume= 30 mL; pH= 6; time = 40 min; T = 50) on the Au(III) adsorption.\u0026nbsp;\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-6054990/v1/e21c98cf5f5752ce5c16eb84.png"},{"id":76825134,"identity":"f7698b9c-a59c-4876-8e2e-89b51f4a8261","added_by":"auto","created_at":"2025-02-21 07:28:15","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":33337,"visible":true,"origin":"","legend":"\u003cp\u003eSelectivity of OCBS@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-SH for Au(III) adsorption in the presence of some interfering agents (Mg, Ni, Cu, Co, Fe, Mn, Cd and Zn)\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-6054990/v1/2398612334bbcd59aeaaf82f.png"},{"id":83783078,"identity":"b8f497d8-6c4f-4194-b5c1-6da7263e1158","added_by":"auto","created_at":"2025-06-02 16:10:37","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1747055,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6054990/v1/fb77a368-cd0d-4f97-aa08-18875d65ab23.pdf"},{"id":76825606,"identity":"49d4c21a-4e67-4bd2-81ae-18fd1ed3a29c","added_by":"auto","created_at":"2025-02-21 07:36:15","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":551627,"visible":true,"origin":"","legend":"","description":"","filename":"Supportinginformation.docx","url":"https://assets-eu.researchsquare.com/files/rs-6054990/v1/61c895e81d0f4b95ce1380f0.docx"},{"id":76825616,"identity":"976501e3-7972-4f0b-b0ff-5445b556fa61","added_by":"auto","created_at":"2025-02-21 07:36:15","extension":"docx","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":77668,"visible":true,"origin":"","legend":"","description":"","filename":"GA.docx","url":"https://assets-eu.researchsquare.com/files/rs-6054990/v1/84176d3d5423d20cd05c3f5d.docx"},{"id":76825609,"identity":"5689b1f4-59ec-41da-a076-0013944d9220","added_by":"auto","created_at":"2025-02-21 07:36:15","extension":"docx","order_by":3,"title":"","display":"","copyAsset":false,"role":"supplement","size":206433,"visible":true,"origin":"","legend":"","description":"","filename":"Schemes.docx","url":"https://assets-eu.researchsquare.com/files/rs-6054990/v1/408ccb32a2051bc7d43cd244.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003eRecovery of Au(III) from electronic waste using solid phase extraction based on a magetic nanobiocomposite, OCBS@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e @UiO-66-SH\u003c/p\u003e","fulltext":[{"header":"Introduction","content":"\u003cp\u003ePrecious metals, known as PM, are used as catalysts, electrical conductors, and corrosion resistance agents due to their physical and chemical properties [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. The electronics and catalyst sectors heavily rely on metals, accounting for over 90% of their usage and showcasing their significant importance. In electronics, gold and silver are chiefly used in manufacturing contacts, bonding wires, and switches of computers, mobile phones, video players, copiers, printers, microwave ovens, refrigerators, and freezers [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Recently, electronic waste (e-waste) production has significantly increased, mainly due to the disposal of electronic products at the end of their life span. E-waste is a crucial source of precious metals, yet only about 20% is recycled, highlighting significant gaps in resource recovery and sustainability efforts [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Gold, widely utilized in electronic devices for its outstanding corrosion resistance and high electrical conductivity, becomes a significant element of electronic waste (e-waste) following the disposal of these gadgets. E-waste contains approximately 6,800 tons of gold, 16% of global reserves, and 25 to 250 times the concentration in natural gold mines, varying from 1 to 10 grams per ton [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Retrieving gold from e-waste is seen as profitable and eco-friendly, offering economic, resource, and environmental benefits. Current gold recovery methods from electronic waste, mainly pyrometallurgical (energy-intensive) and hydrometallurgical (using aqua regia), lead to substantial pollution and are environmentally harmful. In contrast, using microorganisms that produce leaching substances for bioleaching offers an eco-sustainable method for extracting valuable metals from electronic waste [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. It is critical to craft a technique for precisely separating and enriching Au(III) from diverse matrices before its instrumental evaluation.\u003c/p\u003e \u003cp\u003eHistorically, a variety of sample preparation methods, such as solvent extraction [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e], cloud point extraction [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e], and solid phase extraction [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e], have been utilized to extract gold ions (Au(III)) from various matrices before analysis. Recent developments in sample preparation aim to simplify processes, reduce scale, automate, increase efficiency, and minimize solvent dependence. Different microextraction techniques have emerged, like liquid phase microextraction (LPME) and solid phase microextraction (SPME). SPME is particularly significant among microextraction techniques. Initially, SPME involved adsorbing target analytes from headspace or liquid samples onto a coated fiber, then desorption into a solvent. Magnetic solid-phase extraction (MSPE) proves beneficial in isolating Au(III) from electronic waste, employing magnetic adsorbents that specifically adhere to desired analytes, enabling straightforward separation via an external magnetic field. This technique reduces solvent use and hazardous waste, offering a greener alternative to conventional extraction methods. It involves customizable magnetic adsorbents that improve the selective extraction and enrichment of Au(III) and other precious metals [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eVarious adsorbents designed for environmental cleanup often face challenges like high costs and complex separation processes, limiting widespread use. So, the need for affordable, practical adsorbents has grown, with agricultural residues becoming valuable for creating cost-effective biosorbents due to their availability, low cost, and unique properties. In particular, corncobs, a residual product from corn processing, are often disposed of or burned, leading to environmental degradation without any positive gain [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Research has demonstrated that corncobs can be successfully used as starting materials in creating various products and activated carbon for water treatment, adsorption, biocatalysis, and hydrogen storage, underlining their potential for sustainable and practical applications. Corncobs, with their porous and fibrous nature, provide a high surface area and numerous binding sites, making them an excellent choice for adsorbent loading over non-biological substrates. They are cost-effective, widely available as an agricultural byproduct, and sustainable. Lignin and cellulose in corncobs strengthen their interaction with different adsorbents, improving their efficacy [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eMOFs are materials defined by their distinctive lattice-like composition, which integrates metal ions bonded through organic bridging ligands, often containing elements like oxygen or nitrogen. The metal ions or clusters function within this structure as pivotal points, linked by stiff or semi-flexible organic ligands. MOFs are renowned for their extensive specific surface areas, high porosity, stability under heat, straightforward manufacturing, adjustable structures, and chemical adaptability [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. They find utility in numerous domains, such as optics, catalysis, biosensing, medical imaging, and the separation and storage of gases.\u003c/p\u003e \u003cp\u003eMOFs play a critical role in extracting and removing heavy metals because of their large surface area, tunable porosity, and functionalization capabilities, all of which increase their adsorption efficiency. Recent developments have shown that MOFs can effectively capture heavy metal ions from water, allowing for proactive water quality management and real-time monitoring [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Many MOFs demonstrate remarkable selectivity for specific heavy metal ions owing to their customizable pore shapes and functional groups. MOFs may be functionalized to improve their ability to remove metal by adding certain functional groups that allow for more selective binding to target metal ions. Functional groups such as sulfonyl, amide, sulfur, and nitrogen significantly enhance the adsorption capacity of MOFs for heavy metals [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eUiO-66-NH\u003csub\u003e2\u003c/sub\u003e is a metal-organic framework (MOF) that has amino groups (-NH\u003csub\u003e2\u003c/sub\u003e) integrated into its structure and is based on an octahedral cluster of zirconium that is linked by terephthalate linkers. UiO-66-NH\u003csub\u003e2\u003c/sub\u003e establishes strong interactions with analytes, including metal ions, through the amino groups present in the linkers [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. Its exceptional thermal and chemical stability, robust coordination bonds, high connectivity, and adjustable pore dimensions make it ideal for selective adsorption and effective separation of metal ions from complex mixtures, with covalent integration of specific functional groups improving its metal ion adsorption capacity and selectivity. UiO-66-NH\u003csub\u003e2\u003c/sub\u003e exhibits considerable adsorption capabilities for a range of metal ions, encompassing Pb(II), Cd(II), Cr(VI), and Au(III), along with notable removal efficiencies achieved within brief contact durations [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. According to the hard-soft-acid-base (HSAB) theory, Au(III) ions, classified as soft acids, tend to be selectively bonded by soft Lewis bases, particularly those with sulfur and nitrogen, through various bonding methods, including ion-exchange, electrostatic, and chelation interactions [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Studies have shown that thiol-functionalized Zr-based MOFs exhibit good efficiency and selectivity for the extraction of Au(III) ions from aqueous samples as well as complex matrices. Therefore, in this work, we utilized thiol-functionalized UiO-66-NH\u003csub\u003e2\u003c/sub\u003e (Zr-based MOF) to fabricate a magnetic bioadsorbent in order to present an adsorbent with high adsorption capacity for Au(III) ions.\u003c/p\u003e \u003cp\u003eIn this study, a zirconium-based MOF (UiO-66-NH\u003csub\u003e2\u003c/sub\u003e) modified with thiol groups on the surface of oxidized magnetic corncobs (OCBS@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-SH) was synthesized for the adsorption and extraction of Au(III) from electronic waste. The OCBS@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-SH was characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA), and Brunauer-Emmett-Teller (BET) techniques. The extraction system, comprising the magnetic adsorbent, was actively stirred on a magnetic stirrer to ensure uniform mixing and interaction within the sample. After completing the process and Au(III) desorption from the adsorbent, Au(III) concentration was determined using a flame atomic absorption spectrometer. The study further explored the influence of various parameters on the adsorbent\u0026rsquo;s efficacy for Au(III) recovery, including sample volume, washing solvent type, and washing solvent volume.\u003c/p\u003e"},{"header":"Materials and methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eChemical and reagents\u003c/h2\u003e \u003cp\u003eThe materials used in this work include acetic acid with a purity of 99.8%, TEMPO with a purity of 98%, sodium hydroxide with a purity of 98%, N,N-dimethylformamide with a purity of 99.8%, and sodium bromide with a purity of 99% were purchased from Merck. Sodium chlorite with a purity of 80%, sodium hypochlorite with a concentration of 10\u0026ndash;15% available chlorine, ferrous sulfate heptahydrate with a purity of 99%, ferric chloride hexahydrate with a purity of 97%, toluene with a purity of 99.8%, chloroacetyl chloride with a purity of 98%, triethylamine with a purity of 99%, zirconium(IV) chloride with a purity of 99.5% and sodium sulfide with a purity of 98% were obtained from Sigma-Aldrich. Other materials are 2-amino terephthalic acid with a purity of 99% (TCI Chemicals), hydrochloric acid with a concentration of 37% (Fisher Scientific), and nitric acid with a concentration of 70% (Fisher Scientific). The devices used include a heating apparatus (IKA C-MAG HS 7), ultrasonic bath (Branson 5800), magnetic stirrer (IKA C-MAG HS 7), and oven 50 (Fur, Behdad, Iran).\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eDelignification and TEMPO oxidation of corncobs\u003c/h3\u003e\n\u003cp\u003eThe preparation steps of OCBs, OCBs-Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e, OCBS@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-NH\u003csub\u003e2\u003c/sub\u003e and OCBS@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-SH nanocomposites are shown schematically in Scheme \u003cspan refid=\"Sch1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. Sodium chlorite was used for delignification of corn, which is usually used for this purpose. For this mean, 10 g of oven-dried corn was added in 700 mL of a solution comprising 7 g of sodium chlorite and 3 mL of acetic acid, heated to 80\u0026deg;C for three hours. The processed corn, named delignification corncobs (DCBs), underwent washing with distilled water to attain a neutral pH level. Following this, TEMPO oxidation was applied to the DCBs, adhering to a technique noted in the literature [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. In this phase, 10 g of DCBs was merged with a 400 mL solution infused with 0.1 g of TEMPO. Sequentially, 1 g of NaBr and 30 mL of NaClO solution were incorporated under constant stirring, with the reaction sustained for four hours at a pH close to 10. Subsequently, the oxidized product, oxidized corncobs (OCBs), was cleansed using deionized water to neutralize the pH and then secured in a sealed bag in a refrigerator.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\n\u003ch3\u003ePreparation of OCBs-FeO nanocomposite\u003c/h3\u003e\n\u003cp\u003eDuring the typical procedure, 1 g of OCBs were ultrasonically treated in 15 mL of distilled water for 15 minutes to achieve dispersion. Following this, 80 mL of an aqueous solution containing 0.556 g of FeSO\u003csub\u003e4\u003c/sub\u003e.4H\u003csub\u003e2\u003c/sub\u003eO and 1.081 g of FeCl\u003csub\u003e3\u003c/sub\u003e.6H\u003csub\u003e2\u003c/sub\u003eO was incrementally introduced to the dispersed OCBs, and the mixture temperature was raised to 40\u0026deg;C. A few NaOH drops were added to bring the pH level to 10. At 80\u0026deg;C, the mixture was stirred for 30 minutes without interruption. The OCBs@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e nanocomposite cooled to ambient temperature was rinsed three times with distilled water and then dried at 80\u0026deg;C under vacuum.\u003c/p\u003e\n\u003ch3\u003ePreparation of OCBS@FeO@UiO-66-NH\u003c/h3\u003e\n\u003cp\u003eTo synthesize OCBS@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-NH\u003csub\u003e2\u003c/sub\u003e, 1 g of the OCBs@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e was dispersed in 45 mL of a solution containing 0.1125 g of ZrCl\u003csub\u003e4\u003c/sub\u003e in DMF (solution A). This mixture was then stirred for 10 minutes. Then, 0.0797 g of 2-amino acids were carefully mixed into Solution A, stirring the blend for 5 minutes. After that, it was placed in an autoclave lined with Teflon and heated to 120\u0026deg;C for one day. Subsequently, the resulting solid product underwent thorough rinsing with water and ethanol. The OCBS@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-NH\u003csub\u003e2\u003c/sub\u003e composite was vacuum-dried at 70\u0026deg;C for 12 hours.\u003c/p\u003e\n\u003ch3\u003ePreparation of OCBS@FeO@UiO-66-SH\u003c/h3\u003e\n\u003cp\u003e15 mL of toluene was added to a mixture containing 1 g of OCBS@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-NH\u003csub\u003e2\u003c/sub\u003e. Ultrasonic waves were used to treat for half an hour. Next 1.01 mL of triethylamine and 0.3164 g of 2-chloroacetyl chloride were added to the mixture, which was then agitated with a stirrer for 12 hours at room temperature. The resulting mixture was washed thrice with toluene and twice with methanol and then left to air dry at room temperature. Then, 1 g of the product obtained was mixed, with a solution of Na\u003csub\u003e2\u003c/sub\u003eS by dissolving 2 g of Na\u003csub\u003e2\u003c/sub\u003eS in 30 mL of DMF. The combined solution was then heated under reflux at 150\u0026deg;C for twelve hours. The solid product was separated using magnets. Rinsed with DMF. After vacuum drying at 60\u0026deg;C for twelve hours, the final product was obtained as OCBS@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-SH.\u003c/p\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eExtraction of Au(III) from electronic waste\u003c/h2\u003e \u003cp\u003eThe process commenced with the thermal decomposition of the scrap to break down its components. Subsequently, silver was extracted by washing it at 40\u0026deg;C using 50 mL of HNO\u003csub\u003e3\u003c/sub\u003e, producing silver nitrate (AgNO\u003csub\u003e3\u003c/sub\u003e) as a byproduct. The remaining materials then underwent a process involving the washing of Au(III) using aqua regia, an HCl:HNO\u003csub\u003e3\u003c/sub\u003e solution (3:1), at 40\u0026deg;C, followed by the disposal of solid waste. Finally, Au(III) was extracted from the resulting solution using OCBS@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-SH, leading to wastewater generation (Scheme \u003cspan refid=\"Sch2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eAu(III) adsorption measurement\u003c/h3\u003e\n\u003cp\u003eOCBS@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-SH was employed as an adsorbent to measure the adsorption of Au(III) in a room-temperature environment. Initially, 30 mL of a 400 mg/L Au(III) solution was combined with 10 mg of OCBS@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-SH. The mixture was stirred at 300 rpm for 40 minutes. The impact of pH on Au(III) adsorption was investigated within the pH range of 2 to 12, and the pH levels were adjusted using hydrochloric acid and sodium hydroxide solutions. The desorption process was carried out with thiourea for 20 minutes. Subsequently, deionized water was used to wash the adsorbent. Following this, flame atomic absorption spectrometry was utilized to analyze the residual Au(III) content in the solution, aiming to evaluate the effectiveness of the adsorption process.\u003c/p\u003e \u003cp\u003eIn this waste study, a mix of 30 mL of Au(III) solution extracted from waste and 10 mg of the adsorbent material were combined in a beaker (50 mL) at pH level 6 and room temperature. The mixture underwent stirring for 40 minutes. Equations\u0026nbsp;\u003cspan refid=\"Equ1\" class=\"InternalRef\"\u003e1\u003c/span\u003e and \u003cspan refid=\"Equ2\" class=\"InternalRef\"\u003e2\u003c/span\u003e were used to determine the removal percentage (R%) and adsorption capacity (\u003cem\u003eq\u003c/em\u003e\u003csub\u003ee\u003c/sub\u003e, mg/g) of Au(III) ions:\u003cdiv id=\"Equ1\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ1\" name=\"EquationSource\"\u003e\n$$\\:{\\:q}_{e}=\\frac{({C}_{0}-{C}_{e})V}{m}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e1\u003c/div\u003e\u003c/div\u003e\u003cdiv id=\"Equ2\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ2\" name=\"EquationSource\"\u003e\n$$\\:R=\\frac{{C}_{0}-{C}_{e}}{{C}_{0}}\\times\\:100$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e2\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003ewhere \u003cem\u003eC\u003c/em\u003e\u003csub\u003e0\u003c/sub\u003e (mg/L) is the initial concentration of the adsorbate in the solution, \u003cem\u003eC\u003c/em\u003e\u003csub\u003ee\u003c/sub\u003e (mg/L) is the equilibrium concentration of the adsorbate after the adsorption process, \u003cem\u003eV\u003c/em\u003e (mL) is the volume of the solution, and \u003cem\u003em\u003c/em\u003e (mg) is the mass of the OCBS@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-SH .\u003c/p\u003e"},{"header":"Results and discussion","content":"\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eCharacterization\u003c/h2\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea displays the FT-IR spectra of OCBs@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e, OCBs@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-NH\u003csub\u003e2\u003c/sub\u003e, OCBs@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-SH, and UiO-66-NH\u003csub\u003e2\u003c/sub\u003e. Two absorption peaks at 3461 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 3361 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e in the FT-IR spectra of UiO-66-NH\u003csub\u003e2\u003c/sub\u003e are attributed to the symmetric and asymmetric N-H stretching vibrations of the primary amine (-NH\u003csub\u003e2\u003c/sub\u003e) functional group that is present in the 2-amino terephthalate linker [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. The 1650 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 1482 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e peaks indicate the C\u0026thinsp;=\u0026thinsp;O stretching vibration of the carboxylate group (-COO-) and the N-H bending vibration of the -NH\u003csub\u003e2\u003c/sub\u003e group in the amino terephthalate linker. The highest peak at 1382 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e is probably attributable to the bending vibrations of the C-N bond, and peaks appearing at about 750 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e are attributed to the Zr-O vibrations [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eDifferences can be seen in the upward shift for the carbonyl peak from 1645 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e in OCBs@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-NH\u003csub\u003e2\u003c/sub\u003e to 1680 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e in OCBs@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-SH. Moreover, two peaks associated with C-S and S-H bonds appeared. In the FT-IR spectrum of OCBs@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-SH, the vibrations related to Zr-O stretching due to \u0026micro;\u003csub\u003e3\u003c/sub\u003e-OH groups in the framework are around 700 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. A \u0026micro;\u003csub\u003e3\u003c/sub\u003e-OH group is a bridging hydroxo group where a hydroxyl group (OH) bridges three metal atoms (in this case, Zr atoms) [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. Stretching modes of S-H and C-S are noticed at 2550 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 1200 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, respectively. Moreover, the C-O stretching vibrations of the cellulose and hemicellulose of OCBs are responsible for the peak at 1200 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. After S-H is functionalized in MOF, the peak at 1650 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e changes to 1680 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, showing that post-synthetic modification of amine-functionalized UiO-66-NH\u003csub\u003e2\u003c/sub\u003e has integrated thiol groups into the structure [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. An intense and broad peak in the 3300\u0026ndash;3400 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e range indicates that the O\u0026ndash;H bonds in the glucose units of starch inside OCBs are expanding. Peaks in the range of 900\u0026ndash;1200 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, with a peak close to 1000 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, are associated with the stretching vibrations of glucose molecules\u0026rsquo; C\u0026ndash;O\u0026ndash;C bonds. The noticeable peak at 580\u0026ndash;590 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e is associated with Fe\u0026ndash;O stretching vibrations in the Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e magnetite structure. In OCBs@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e spectrum, peaks detected at 1612 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 565 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e validate the existence of C\u0026ndash;O and Fe\u0026ndash;O vibrations.\u003c/p\u003e \u003cp\u003eThe XRD patterns of OCBs@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e, OCBs@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-NH\u003csub\u003e2\u003c/sub\u003e, OCBs@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-SH, and UiO-66-NH\u003csub\u003e2\u003c/sub\u003e are presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb.\u003c/p\u003e \u003cp\u003eThe XRD pattern of the UiO-66-NH\u003csub\u003e2\u003c/sub\u003e material shows peaks at 2\u0026#120579;= 7.2\u0026deg;, 8.1\u0026deg;, and 25.0\u0026deg; representing the crystal planes (111), (200) and (731), respectively, indicating its nature and successful creation. The composite of OCBs@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e peaks at around 15\u0026deg;, 16\u0026deg;, and 22.5\u0026deg;, signifying the corncob cellulose structure within it [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. Diffraction peaks at angles of 31\u0026deg;, 34\u0026deg;, 43\u0026deg;, 52\u0026deg;, 57\u0026deg;, and 62\u0026deg;, which correlate to the Miller indices of (220), (311), (400), (422), (511), and (440), are seen to establish the existence of the magnetite Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e phase. Additionally, distinct peaks characteristic of UiO-66-NH\u003csub\u003e2\u003c/sub\u003e and OCBs@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e are also noted in the OCBS@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-NH\u003csub\u003e2\u003c/sub\u003e material, indicating the synthesis of all components into a nanocomposite. The XRD patterns for OCBS@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-NH\u003csub\u003e2\u003c/sub\u003e and OCBS@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-SH show similarities, with variations noted between them.\u003c/p\u003e \u003cp\u003eThe SEM images of OCBs-Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e and OCBS@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-SH are presented in the Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e \u003cp\u003eThe SEM image of OCBs@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e(A)) reveals a porous structure composed of numerous small, spherical particles. The bright spots are likely Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e nanoparticles deposited on the surface of the OCBS [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. The underlying substrate appears irregular and porous, which can be attributed to the carbon material derived from OCBS. As evident, the surface of the OCBS-derived carbon acts as a high surface area substrate for loading Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e nanoparticles, thereby preventing their aggregation to some extent. The SEM image of OCBS@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-SH (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e(B)) depicts a 3D porous structure containing particles with irregular shapes and sizes. The rough and textured surface, with small protrusions and cavities, is characteristic of MOFs like UiO-66, and the surface roughness indicates functionalization with thiol groups. Based on this SEM image, it appears that the magnetic Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e nanoparticles are well-loaded within and between the MOF particles and on the surface of the OCBS-derived carbon [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e shows the TGA curves of UiO-66-NH\u003csub\u003e2\u003c/sub\u003e and OCBS@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-SH. The moisture in the sample causes weight loss of about 10% at temperatures between 20\u0026deg;C and 131\u0026deg;C. A 5% reduction in temperature at 281\u0026deg;C may result from the depletion of surface groups or organic compounds, including ligands or functional groups. The 39% reduction at 675\u0026deg;C is presumably attributable to the disintegration of the primary MOF structure, resulting in the framework's collapse and subsequent loss of the composite [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn contrast, in OCBs@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-SH nanocomposite, the loss weights after raising the temperature to 131\u0026deg;C, 281\u0026deg;C, and 675\u0026deg;C are 3%, 7% and 52%, respectively. The first 3% weight reduction at 131\u0026deg;C signifies the expulsion of moisture or low-molecular-weight substances. The 7% weight reduction at 281\u0026deg;C is ascribed to the breakdown of organic constituents or partial disintegration of the composite. The significant weight reduction of 52% at 675\u0026deg;C signifies considerable thermal deterioration, presumably resulting from the disintegration of the UiO-66 framework, highlighting the thermal constraints of the composite. The TGA curves represent that the weight loss in UiO-66-NH\u003csub\u003e2\u003c/sub\u003e occurs at a lower temperature range compared to the OCBs@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-SH composite, indicating that the incorporation of OCBs and Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e nanoparticles into the UiO-66-SH framework enhances its thermal stability [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. It is observed that, after the temperature of 600\u0026deg;C, the weight loss of OCBS@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-SH is higher because, at this temperature, corn also decomposes at a high rate. According to literature, corncob begins to decompose at 210\u0026deg;C and decomposes entirely around 600\u0026deg;C. In this work, due to the strong interaction between corncob and the components (UiO-66-SH and Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e), the stability of the corn also increases, and it begins to degrade at higher temperatures.\u003c/p\u003e \u003cp\u003eThe BET analysis was performed for Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-SH and OCBS@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-SH, the results are presented in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\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\u003eBET analysis results of Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-SH and OCBs@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-SH\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\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 \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eV\u003csub\u003em\u003c/sub\u003e\u003c/p\u003e \u003cp\u003e(cm\u003csup\u003e3\u003c/sup\u003e/g)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003ea\u003csub\u003es,BET\u003c/sub\u003e\u003c/p\u003e \u003cp\u003e(m\u003csup\u003e2\u003c/sup\u003e/g)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eV\u003csub\u003ep,T\u003c/sub\u003e (P/P\u003csub\u003e0\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;0.990)\u003c/p\u003e \u003cp\u003e(cm\u003csup\u003e3\u003c/sup\u003e/g)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003ed\u003csub\u003ep,m\u003c/sub\u003e\u003c/p\u003e \u003cp\u003e(nm)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"4\" nameend=\"c4\" namest=\"c1\"\u003e \u003cp\u003eFe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-SH\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1.5841\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e66.6428\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.019642\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e11.396\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"4\" nameend=\"c4\" namest=\"c1\"\u003e \u003cp\u003eOCBs@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-SH\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1.7735\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e84.5466\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.020234\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e10.485\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eThe BET analysis results for Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-SH and OCBs@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-SH reveal key differences in their surface area and porosity characteristics. Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-SH exhibited a monolayer adsorption capacity (V\u003csub\u003em\u003c/sub\u003e) of 1.5841 cm\u003csup\u003e3\u003c/sup\u003e/g, a specific surface area (a\u003csub\u003es,BET\u003c/sub\u003e) of 66.6428 m\u0026sup2;/g, a total pore volume (V\u003csub\u003ep,T\u003c/sub\u003e) of 0.019642 cm\u003csup\u003e3\u003c/sup\u003e/g, and an average pore diameter (d\u003csub\u003ep,m\u003c/sub\u003e) of 11.396 nm. In comparison, OCBs@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-SH demonstrated a higher V\u003csub\u003em\u003c/sub\u003e of 1.7735 cm\u003csup\u003e3\u003c/sup\u003e/g, a more significant a\u003csub\u003es,BET\u003c/sub\u003e of 84.5466 m\u0026sup2;/g, a slightly larger V\u003csub\u003ep,T\u003c/sub\u003e of 0.020234 cm\u0026sup3;/g, but a smaller d\u003csub\u003ep,m\u003c/sub\u003e of 10.485 nm. These findings highlight the impact of OCBs incorporation on the material\u0026rsquo;s adsorption properties, suggesting potential advantages in applications where higher surface area and specific pore size distributions are desired.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003eOptimization study of operating conditions\u003c/h2\u003e \u003cdiv id=\"Sec13\" class=\"Section3\"\u003e \u003ch2\u003eThe effect of pH on Au(III) adsorption\u003c/h2\u003e \u003cp\u003eThe Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea illustrates how much Au(III) (mg/g) was adsorbed on OCBs@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-SH composite at different pH values. At low pH (2\u0026ndash;4), some functional groups (eg, -SH and -COOH) on the surface of composites may be protonated, and the binding sites for Au(III) can be significantly reduced.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe apparent increase in the adsorption capacity is observed from pH 4 to 6, and the maximum is seen at around pH 6. At very low pH, H\u003csup\u003e+\u003c/sup\u003e ions may compete with Au(III) for binding sites, diminishing adsorption efficacy. Still, at elevated pH, Au(III) are likely to transform into gold hydroxides and precipitate, rendering them less accessible for adsorption. At pH 6, a balance exists between the stability and availability of Au(III) species in solution and the functional groups on the composite that are accessible for binding. Furthermore, the -SH groups get protonated in lower pH circumstances (more acidic), diminishing their affinity for Au(III). Conversely, at elevated pH levels (more alkaline circumstances), the -SH and -COOH functional groups deprotonate, resulting in a negatively charged surface that induces electrostatic repulsion with the anionic Au(III) species [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e].\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003eThe effect of time on Au(III) adsorption\u003c/h2\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb depicts the adsorption capacity of Au(III) onto an OCBS@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-SH composite in 10\u0026ndash;45 minutes at room temperature. It is evident that the adsorption capacity increases rapidly and this increase continues until 30 minutes. From 30 to 40 minutes, the adsorption capacity reaches saturation and does not show much change, so that after 40 minutes it reaches a constant value. This shows that at 40 minutes the adsorption capacity of the adsorbent reaches its maximum value and more time has no effect on increasing the adsorption capacity [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e].\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003eThe effect of temperature on Au(III) adsorption\u003c/h2\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ec shows that the adsorption capacity of OCBS@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-SH composite material for Au(III) increases with increasing temperature from 25\u0026deg;C to 50\u0026deg;C. This trend can occur for several reasons. The first reason is that as the temperature increases, the kinetic energy of Au(III) or particles also increases, resulting in higher mobility of Au(III) and more adsorbing on the adsorption site, leading to better adsorbing effect and higher adsorption capacity. The second reason is that higher temperatures will increase the mass transfer of Au(III) from bulk solution into or onto the composite material surface, which is the way that higher temperatures increase the motion and diffusion of Au(III) into the adsorbent surface. The Au(III) adsorption on composite is likely an endothermic process, meaning that higher temperatures increase the activation energy needed for Au(III) species to overcome the energy barrier for attaching to the adsorption sites [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e].\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec16\" class=\"Section2\"\u003e \u003ch2\u003eThe effect of concentration on Au(III) adsorption\u003c/h2\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ed shows the results of an investigation into the impact of increasing the concentration of Au(III) from 100 mg/L to 900 mg/L on its absorption by OCBS@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-SH composite. It is evident that as the initial concentration of Au(III) grows, so does the composite's adsorption capability. This is because there are enough adsorption sites on the composite surface at lower concentrations, and raising the concentration of Au(III) is likely to increase the number of Au(III) ions that can be adsorbed to the available adsorption sites, thereby increasing the adsorption capacity [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. On the other hand, because all adsorption sites accessible at lower concentrations are occupied, the available adsorption sites are likely to be saturated when the concentration is raised. Therefore, increasing the Au(III) concentration hardly helps to improve the adsorption capacity, which is why the absorption curve decreases at high concentrations The high surface area, porosity, and binding groups of UiO-66 MOF provide many adsorption species at the particle surface. In contrast, the thiol functional group (-SH) provides a strong affinity for Au(III) binding [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]. The quantity of absorption capacity found in this investigation demonstrated that the amount of absorption rises with concentration. It is also evident from Table \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e that the OCBs@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-SH have an adsorption capacity that is within the literature limit and, in some instances, more excellent for Au(III) in solution. The adsorption capacity of several adsorbents reported for Au(III) adsorption in the literature is also shown in Table \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e.\u003c/p\u003e \u003cp\u003eOur proposed adsorbent shows a competitive adsorption capacity (1587 mg/g) under the following conditions: 10 mg adsorbent, volume of Au(III) solution 30 mL, pH 6, and temperature 50\u0026deg;C. As can be seen, our adsorbent has a higher adsorption capacity than the polymer containing N (based on MOP) (1073 mg/g) [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e], CoFe\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@S-CoWO\u003csub\u003e4\u003c/sub\u003e (1049 mg/g) [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e] and M-Cu-BDC-NH\u003csub\u003e2\u003c/sub\u003e (1184 mg/g) [\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e]. Our OCBS@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-SH adsorbent shows competitive performance in adsorption capacity, works at near-neutral pH, and reaches equilibrium relatively quickly, indicating that it can be a promising material for Au(III) adsorption applications. Isotherm models as well as kinetic models were used to investigate the mechanism and rate of adsorption, the results of which are presented in the supporting information file.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec17\" class=\"Section2\"\u003e \u003ch2\u003eAdsorption selectivity\u003c/h2\u003e \u003cp\u003eBecause e-waste contains many metal ions, the solution\u0026rsquo;s composition is complex, which leads to a high degree of competitive adsorption ions. Thus, evaluating Au(III)\u0026rsquo;s adsorption selectivity is crucial. As Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e illustrates, there is negligible adsorption of Mg, Mn, Cu, Zn, Co, Cd, Ni, and OCBS@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-SH exclusively catch Au(III) when the mass ratios of Au(III) to competing ions are set at 1:1 and even extended to 1:5. As can be seen, the \u003cem\u003eq\u003c/em\u003e\u003csub\u003ee\u003c/sub\u003e value for Au(III) is about 550 mg/g for both ratios, which is significantly higher than any other metal. This indicates that the extraction method used is highly selective for Au(III), even in the presence of several different metals.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFor intervening metals, the extraction efficiency is much lower and below 50 mg/g. Cu, with a \u003cem\u003eq\u003c/em\u003e\u003csub\u003ee\u003c/sub\u003e value of about 30 mg/g in 1:1 conditions and a little less in 1:5 conditions, shows the highest extraction among the intervening metals. Other metals, such as Fe and Mn have low extraction efficiency (below 20 mg/g). It is interesting to note that the ratio of Au(III) to interfering metals does not have a significant effect on Au(III) extraction efficiency. However, for some interfering metals such as Cu and Co, the extraction efficiency is slightly higher in the 1:1 condition than in the 1:5 condition. As a result, the extraction method used is highly selective for Au(III) and achieves excellent separation from other metals usually found in complex mixtures. Thus, our findings demonstrate that OCBS@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-SH has exceptional selectivity in differentiating Au(III) from other coexisting interfering metals.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec18\" class=\"Section2\"\u003e \u003ch2\u003eAdsorption kinetic and thermodynamic parameters\u003c/h2\u003e \u003cp\u003eIn the continuation of this work, the adsorption process model and its kinetic and thermodynamic studies were also investigated, the results of which are provided as a file in the supplementary information section.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec19\" class=\"Section2\"\u003e \u003ch2\u003eAnalysis of real sample\u003c/h2\u003e \u003cp\u003eValidation of the suggested technique for extracting Au(III) was conducted on calculator scrap, PC board scrap, mobile phone scrap and PC mainboard scrap, and the findings are shown in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. The conventional standard addition method was used to quantify the content of Au(III) in electronic waste samples. To examine the recovery of Au(III), a standard solution containing Au(III) at two different concentrations (20 and 40 mg/L) was introduced into the extracted Au(III) samples. The amount of Au(III) found in the calculator scrap, PC board scrap, mobile phone scrap, and PC mainboard scrap samples were 107.03, 125.90, 157.98, and 205.15 ppm, respectively. Moreover, the recovery rates for the spiked samples ranged from 95.30\u0026ndash;104.75%. The achieved recoveries within the 95.30\u0026ndash;104.75% range, indicating impressive concordance between the spiking and extracted levels. The recovery of Au(III) was successful, and the productivity of Au(III) extraction was not influenced by the matrix of the three electronic waste samples.\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\u003eDetermination of Au(III) in electronic waste samples\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colspan=\"4\" nameend=\"c4\" namest=\"c1\"\u003e \u003cp\u003eAmount of Au(III) (ppm)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSample\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAdded\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eFound\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eRecovery (%)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCalculater scrap\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e107.03\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e127.40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e101.85\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e145.60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e96.40\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePC board scrap\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e125.90\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e144.96\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e95.30\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e167.20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e103.25\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMobile phone scrap\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e157.98\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e178.80\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e104.10\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e196.80\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e97.05\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e205.15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePC mainboard scrap\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e226.10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e104.75\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e245.40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e100.62\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThis work introduced a novel adsorbent based on corncob (OCBS@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-SH) to extract Au(III) from real samples efficiently. Characterization of composite with FT-IR, XRD, FESEM, BET, and TGA analysis proved that this adsorbent is synthesized successfully. The effects of pH, time, and temperature. Examining the impact of pH in the range of pH 2.0 to 12.0 on the absorption of Au(III) showed the maximum absorption capacity around pH 6. Moreover, the adsorption capacity rises up to 40 minutes with the adsorbent, implying that all active sites are occupied and the system is in equilibrium. After 40 minutes, the capacity does not vary substantially. Additionally, the absorption capacity of the OCBS@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-SH composite material for Au(III) increases as the temperature rises from 25\u0026deg;C to 50\u0026deg;C. Our findings demonstrated that OCBS@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-SH has exceptional selectivity in differentiating Au(III) from other coexisting interfering metals (Mg, Mn, Cu, Zn, Co, Cd, Ni). The study validated a technique for extracting Au(III) from various electronic waste samples, including calculator scrap, PC board scrap, mobile phone scrap, and PC mainboard scrap. The recovery rates ranged from 95.30\u0026ndash;104.75%, demonstrating the technique\u0026rsquo;s effectiveness regardless of the electronic waste source. The results of data fitting with different isotherm models showed that the Langmuir model, with the highest R\u003csup\u003e2\u003c/sup\u003e value, is the most suitable model for interpreting experimental data. This evidence indicates that the adsorption mechanism is monolayer, and the adsorption process proceeds with minimal interaction between the adsorbed molecules. The kinetics are primarily governed by the interaction of the adsorbent molecules with surface sites, which is consistent with the fundamental ideas of the PFO model, as shown by the excellent agreement between the calculated and observed qe values and the high R\u003csup\u003e2\u003c/sup\u003e value. Thermodynamic studies revealed that the spontaneous adsorption process is represented by the negative Δ\u003cem\u003eG\u003c/em\u003e\u0026deg; values obtained in the temperature range of 298 to 323 K, and the positive adsorption enthalpy value shows the heat of the surface adsorption process. Furthermore, the system\u0026rsquo;s degree of disorder increases, as demonstrated by the positive Δ\u003cem\u003eS\u003c/em\u003e\u0026deg; (13.52 J/mol\u0026middot;K), implying that the adsorbed molecules are more uniformly dispersed on the surface, potentially enhancing the adsorption capacity.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eFunding\u003c/h2\u003e \u003cp\u003eThis work was supported by the University of Kurdistan (No. 9813008101).\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eParisa Poormoghadem and Soleiman Bahar made substantial contribution to the conception or design of the work; or the acquisition, analysis, or interpretation of data used in the work; and also Yones Naghdi contributions to the synthesis of adsorbent.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eZientek ML, Loferski PJ (2014) Platinum-Group Elements - So Many Excellent Properties. 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Sep Purif Technol 335:126131. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.seppur.2023.126131\u003c/span\u003e\u003cspan address=\"10.1016/j.seppur.2023.126131\" 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":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"microchimica-acta","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"miac","sideBox":"Learn more about [Microchimica Acta](https://link.springer.com/journal/604)","snPcode":"604","submissionUrl":"https://submission.springernature.com/new-submission/604/3","title":"Microchimica Acta","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Au(III), Magnetic solid phase extraction, Zirconium-based MOF, Langmuir isotherm","lastPublishedDoi":"10.21203/rs.3.rs-6054990/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6054990/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThis study created a zirconium-based MOF (UiO-66-NH\u003csub\u003e2\u003c/sub\u003e) with thiol groups attached to its magnetic corn surface for adsorption and extraction of Au(III) from electronic waste. Characterization of the composite was verified using FTIR, XRD, FESEM, TGA and BET techniques. The temperature, adsorption period, and pH on Au(III) adsorption were investigated. The pH of solutions significantly impacts Au(III) adsorption, with pH 6.0 being the optimal value. The optimum Au(III) adsorption conditions were 50 ◦C, 40 min, and 10 mg of adsorbent. Moreover, functionalized oxidized magnetic corncobs with thiol (OCBS@Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@UiO-66-SH) showed a notable ability to adsorb Au(III) with a 1587 mg/g capacity. With mass ratios of Au(III) to competing ions (Mg, Mn, Cu, Zn, Co, Cd, and Ni) fixed at 1:1 or extended to 1:5, this adsorbent prefers Au(III) ions while showing negligible adsorption to other ions. The study validated a technique for extracting Au(III) from various electronic waste samples, achieving high recovery rates (95.30\u0026ndash;104.75%), demonstrating its effectiveness and lack of matrix interference. Langmuir, Freundlich, and Temkin isotherm models were used to describe the adsorption process. Comparing models, the Langmuir model with the most excellent R\u003csup\u003e2\u003c/sup\u003e value is best for interpreting experimental adsorption data. Among three kinetic models, pseudo-first-order (PFO), pseudo-second-order (PSO) kinetic, and interparticle diffusion (ID) models, PFO model exhibited a high R\u003csup\u003e2\u003c/sup\u003e value (0.9976). Thermodynamic calculations reveal a positive Δ\u003cem\u003eH\u003c/em\u003e\u0026deg;, indicating the endothermic process, and negative Δ\u003cem\u003eG\u003c/em\u003e\u0026deg; values representing spontaneous adsorption at 298\u0026ndash;323 K. The positive Δ\u003cem\u003eS\u003c/em\u003e\u0026deg; shows that the adsorbed molecules are more uniformly dispersed on the surface, potentially enhancing the adsorption capacity.\u003c/p\u003e","manuscriptTitle":"Recovery of Au(III) from electronic waste using solid phase extraction based on a magetic nanobiocomposite, OCBS@Fe3O4 @UiO-66-SH","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-02-21 07:28:10","doi":"10.21203/rs.3.rs-6054990/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-03-12T06:01:43+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-03-11T18:50:16+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-03-07T03:24:12+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"14944406571661741911465066237980419012","date":"2025-02-26T11:27:42+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"16490114824337758099268239316927420875","date":"2025-02-23T12:40:21+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-02-23T11:25:32+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-02-19T09:13:04+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-02-19T09:11:03+00:00","index":"","fulltext":""},{"type":"submitted","content":"Microchimica Acta","date":"2025-02-18T09:51:49+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"microchimica-acta","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"miac","sideBox":"Learn more about [Microchimica Acta](https://link.springer.com/journal/604)","snPcode":"604","submissionUrl":"https://submission.springernature.com/new-submission/604/3","title":"Microchimica Acta","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"6fb68d68-594c-4e79-bf73-b9c01913091b","owner":[],"postedDate":"February 21st, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-06-02T16:06:07+00:00","versionOfRecord":{"articleIdentity":"rs-6054990","link":"https://doi.org/10.1007/s00604-025-07247-1","journal":{"identity":"microchimica-acta","isVorOnly":false,"title":"Microchimica Acta"},"publishedOn":"2025-05-28 15:57:47","publishedOnDateReadable":"May 28th, 2025"},"versionCreatedAt":"2025-02-21 07:28:10","video":"","vorDoi":"10.1007/s00604-025-07247-1","vorDoiUrl":"https://doi.org/10.1007/s00604-025-07247-1","workflowStages":[]},"version":"v1","identity":"rs-6054990","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6054990","identity":"rs-6054990","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}