Selective Adsorption Mechanism Research Articles

Wood meet MOFs: Facile, green, and highly selective adsorbent for textile wastewater

Owing to their unique physicochemical features, ionic liquids (ILs) are extensively utilized to dissolve cellulose for the preparation of regenerated cellulose fibers (RCFs) in the textile industry. However, Cu2+ is introduced during the cellulose dissolution process and gradually accumulates, seriously affecting the RCF performance and IL recovery. Herein, to achieve an efficient and selective adsorption of Cu2+ from ILs aqueous solutions, a facile and green method based on the in situ growth of zeolitic imidazolate framework-67 in wood hydrogels (ZIF-67@WH) is presented. The morphology, functional groups, crystallinity, thermal stability, and pore structure of the resulting ZIF-67@WH were investigated using various characterization techniques, and the adsorption selectivity, adsorption thermodynamics, adsorption kinetics, and recoverability were examined in depth by performing batch experiments. The ZIF-67@WH exhibits high adsorption selectivity for Cu2+ and ILs with adsorption ratios of 92.8 % and 2.2 %, respectively. The selective adsorption mechanism was elucidated by means of FT-IR, XPS, DFT, and MD. As the key for the selective adsorption, the N site in ZIF-67 dramatically promotes the coordination with Cu2+, while the adsorption for ILs mainly occurs via hydrogen bonding and van der Waals interactions with adsorption energies of –80.61 and –35.33 kcal/mol, respectively. The results demonstrate that this approach constitutes a feasible technique for the efficient separation of Cu2+ and ILs in the textile industry.

An environmentally friendly depressant for magnesite and calcite flotation separation: Selective depression and adsorption mechanism

The similar crystal structures and chemical properties of magnesite and calcite make their effective separation through flotation challenging. This study explores the use of Glutamic acid diacetic acid tetrasodium salt (GLDA), a novel environmentally friendly chelating reagent, to enhance the flotation separation of magnesite and calcite. Flotation test results indicate that in a sodium oleate (NaOL) system, GLDA selectively inhibits the flotation of calcite. Under optimal conditions (slurry pH=9.20, GLDA 15 mg/L, and NaOL 140 mg/L), a flotation concentrate with an MgO grade of 46.21 %, CaO grade of 1.39 %, and an MgO recovery rate of 73.17 % was achieved. GLDA minimally affects the hydrophobicity of magnesite but significantly reduces the hydrophobicity of calcite. The selective inhibition mechanism of GLDA was investigated using zeta potential measurements, FTIR, and XPS analyses. Results show that GLDA selectively reacts with Ca sites on the calcite surface, adsorbing and covering it, thereby preventing NaOL from adsorbing on the calcite. Conversely, GLDA has a minor impact on the Mg sites on the magnesite surface, resulting in a negligible effect on NaOL adsorption by magnesite. Consequently, GLDA enhances the flotation separation efficiency of magnesite and calcite. The research results have potential for application in the purification of low-grade magnesite ore.

The selective adsorption mechanism of calcium ions/pullulan in the flotation separation of chalcopyrite from talc

The flotation separation of chalcopyrite from talc by use of pullulan and sodium butyl xanthate (SBX) under calcium ions was investigated in this study. The single mineral flotation shows that SBX collector had a good collecting ability for chalcopyrite while talc had a good natural floatability. The talc flotation was observably depressed while that of chalcopyrite was not affected in the presence of pullulan alone. With the addition of calcium ions. The depression of talc could be achieved with a small amount of pullulan. The artificial chalcopyrite/talc mixture flotation tests reveal that the addition of pullulan could realize the separation of chalcopyrite from talc in the absence and presence of calcium ions, and the dosage of pullulan with calcium ions was lower than that in the absence of calcium ions. Zeta potential measurements suggest pullulan was easily adsorbed onto the calcium ions treated talc surface, and the XPS tests further confirm that calcium ions could selectively adsorb onto the talc surface and increase its activated sites for hydrogen bonding with pullulan molecules. This study is expect to provide a novel polysaccharide depressant for the beneficiation of chalcopyrite from talc.

Mechanism of selective uranium adsorption using polyvinyl alcohol /Cyphos IL-101 / reduced graphene oxide composites

A novel composite material for uranium extraction from seawater, APGO, was prepared by crosslinking reduced graphene oxide (rGO) loaded with trihexyl(tetradecyl)phosphonium chloride (Cyphos IL-101) with polyvinyl alcohol. The experimental results indicate that the surface of APGO contains functional groups, such as carboxyl, hydroxyl, and phosphate, that have adsorption properties for uranium. APGO exhibits excellent hydrophilicity and stability while preserving the intact two-dimensional network structure of rGO. The specific surface area of APGO was 9.23 m2/g with an average pore size of 27.50 nm. Furthermore, the optimal pH range for APGO to adsorb uranium is 6–8, making it more suitable for extracting uranium from seawater. Notably, the selective adsorption capacity of APGO for uranium is significantly enhanced compared to that of AGO, with a Kd value approximately 4.6 times higher than that of AGO. The theoretical adsorption capacity is 467mg/g at 318 K (pH = 6). The process of uranium adsorption by APGO is a spontaneous endothermic reaction. The adsorption performance of APGO is noteworthy because it exhibits only a 2 % decrease after five adsorption–desorption cycles. Furthermore, APGO demonstrates commendable recyclability. Overall, APGO demonstrates a remarkable affinity for uranium and promising potential for efficiently extracting uranium from seawater.

Selective adsorption behaviors and mechanisms of benzyl quaternary ammonium salt on quartz and gypsum: A combined experimental and theoretical study

Benzyl quaternary ammonium salt is an effective collector of quartz from gypsum. To investigate the selective collection mechanism of tetradecyl dimethyl benzyl ammonium chloride (TDBAC) for quartz from a microscopic view, the adsorption experiments, first-principles calculations based on density functional theory (DFT), and molecular dynamics (MD) simulation were performed in this work. The adsorption experiment results show that the adsorption capacity of TDBAC on the quartz surface was 1.6 × 10−6 mol/m2, much larger than that on the gypsum surface (1.0 × 10−7 mol/m2). The interaction energy of TDBAC with quartz surface was −20202.98 kJ/mol, much smaller than that with gypsum surface (-78.37 kJ/mol). DFT calculation results indicate that the quartz surface was more likely to interact with TDBAC through electrostatic attraction since the average negative charge and exposure oxygen density of the quartz surface were both greater than those of the gypsum surface. After the adsorption of TDBAC, there were hydrogen bonds formed between the hydrogen atoms in TDBAC and the oxygen atoms on the quartz surface. This work confirmed that the highly selective adsorption of TDBAC on quartz surface was attributed to the strong electrostatic attraction and hydrogen-bond interaction.

Constructing yeast-modified polypropylene amidoxime membrane toward highly-selective adsorption of U(VI) from seawater

To extract uranium from seawater, the adsorbent needs to have high selectivity for uranium and good hydrophilicity, and could resist biological pollution and prevent Marine microorganisms from blocking chelate sites. For effective uranium extraction, a straightforward crosslinking technique is used to create a highly selective and biofouling-resistant poly(amidoxime) (PAO-Y) membrane. PAO-Y is characterized by FT-IR, SEM, EDS, XPS, BET, WCA and NMR techniques. The effects of solution acidity, concentration, and adsorption time on its adsorption of uranyl ions and vanadyl ions are investigated. The composite material (PAO-Y) exhibits higher selective adsorption and affinity towards U(VI) compared to V(V). In simulated marine environment experiments, the material exhibited an adsorption capacity of 10.39 mg·g−1 for U(Ⅵ), which is five times higher than that for V(V). Furthermore, the adsorption partition constant for U(Ⅵ) is 1.44 × 105 mL·g−1, two orders of magnitude greater than that for V(V). The DFT calculations revealed specific coordination modes between PAO-Y and uranyl/vanadyl ions, elucidating the selective adsorption mechanism of uranium. The pentadentate coordination mode is shown by DFT calculations to be the most stable one. DFT calculations also show that the increase in the number of amino acid groups increases the interaction between the coordinating ligands and uranyl, but decreases the interaction between the coordinating ligands and vanadyl. These findings suggest that PAO-Y effectively enhance the selectivity and affinity towards uranyl ions during uranium extraction from marine environments and may find practical applications. After 15 days of continuous flow of 30 L natural seawater, PAO-Y obtained a total uranium capture capacity of 1.969 mg·g−1 in the fixed-bed adsorption system, making it a suitable candidate for uranium extraction from natural seawater.

Selective adsorption of divalent and trivalent cations in porous electrodes.

The capacitive deionization technology uses the electrochemical adsorption of ions in porous electrodes to desalinate seawater or brackish water. Recently, capacitive deionization has gained significant attention as a technology for selective adsorption of ionic species from multicomponent aqueous electrolytes. To investigate the mechanism of selective adsorption at the molecular level, we performed molecular dynamics simulations of aqueous electrolytes and porous electrodes with different divalent or trivalent ions, electrode pore sizes, and applied voltages. We calculated the free energy barriers preventing ions from entering the pores of the electrode and the structure of the water molecules near the ions and the electrode surface under various conditions. Our results suggest that, when the pore and ion sizes are comparable, the steric and electrostatic interactions between the hydrated ions and electrode pores are comparable in magnitude. Moreover, the relative importance of the two interactions can be reversed by slight changes in the external conditions, such as the ion size, valence of the ions, electrode pore size, and applied voltage. Thus, by finely tuning the electrode pore size and the applied voltage, it may be possible to selectively adsorb a particular ionic species from a multicomponent electrolyte through capacitive deionization using a porous electrode.

Nitrogen-Doped High-Surface-Area activated carbon: Innovative adsorbent for enhanced SO2 and benzene removal

In this paper, we investigated the properties of nitrogen-doped activated carbon produced via the co-activation of KSCN and KOH, using hydrothermal lignin as a precursor. The resulting activated carbon exhibited a high specific surface area of 3504 m2/g and contained 3.37 % nitrogen from KSCN, which enhanced its adsorption efficiency. The adsorption capacities for SO2 and benzene at 273 K were measured at 2260.68 mg/g and 1668.90 mg/g, respectively. Competitive adsorption experiments at 298 K showed that in the presence of SO2, the activated carbon maintained a high adsorption capacity for benzene at 1008.81 mg/g, while the adsorption capacity for SO2 decreased to only 12.31 mg/g, indicating a higher affinity for benzene. The selectivity coefficient, calculated using the Ideal Adsorbed Solution Theory (IAST), reached 44.76 at a benzene-to-SO2 ratio of 2:1. To gain deeper insights into the selective adsorption mechanism, Density Functional Theory (DFT) simulations were conducted. These simulations confirmed the experimental findings, indicating that benzene can be selectively adsorbed and effectively separated from SO2 flue gas.

Understanding pore features of pillar-layered MOFs on one-step C2H4 purification from C2H6/C2H4 mixtures

Purification of ethylene from ethane through adsorption separation is a key industrial process in present chemical field, since the similar physical properties of both C2H4 and C2H6 that makes them difficult to separate. Therefore, constructing C2H6-selective adsorbents and clarifying its structure–activity relationship is a very difficult undertaking. In this study, 3D pillar-layered metal organic frameworks (MMOF-kgm (M = Zn, Co, Ni) and NiMOF-sql) with different topologies, kagome and square lattice, were constructed by using the cheap ligands (1,4-benzenedicarboxylic acid and triethylenediamine). The effect of pore features on C2H6/C2H4 separation performance and the separation mechanism were systematically investigated by the above two isomeric MOFs. In particular, NiMOF-kgm with kagome topology provides narrower triangular pore shows notably adsorption of C2H6 over C2H4, which is validated by gas adsorption, IAST selectivity and breakthrough measurements. The selective adsorption mechanisms of MOF with kagome topology were further revealed through DFT calculations. This study provides in-depth insights into optimizing the pore structure of MOFs to enhance C2H6/C2H4 separation performance, offering new design strategies for developing efficient materials for ethane-selective adsorbent for one-step ethylene purification.

C-doped [formula omitted] monolayer as toxic gas scavenger or sensor based on first-principles study

The selective adsorption mechanism of C-CdS2 monolayer was revealed using density functional theory. The results show that C-CdS2 has good adsorption properties for SO2, NO, NH3, NO2 and Cl2, and all of them are chemisorbed. Under the adsorption of different gas molecules, the electronic structure of C-CdS2 changed to varying degrees, which provided a theoretical basis for the use of C-CdS2 as a gas sensor or scavenger for these gases.

Selective adsorption and corrosion mechanism of SO2 and its hydrates on X65 welded joints steel in CO2-saturated aqueous solution

In this study, the corrosion mechanism in different regions of the welded joints in CO2/SO2 saturated aqueous solution was investigated by electrochemistry and morphological analysis. The results demonstrated that SO2 and its hydrolysis have some adsorption properties and tend to adsorb in the region of the base metal and generated FeS product. A dense corrosion product film could form on this region, effectively reducing the corrosion rate. Due to the selective adsorption which increases the potential difference between different regions of the welded joint, further intensifying the galvanic corrosion and ultimately leading to the failure of the welded joint.

Selective adsorption behavior of reducing gases on the NiO–In2O3 heterojunction under the interfacial effect

Gas sensors with the p–n heterojunction have demonstrated distinct sensing responses to reducing gases, yet a clear understanding of the reaction pathways and selective adsorption mechanisms for specific gas components remains elusive, impeding practical applications. In this study, we constructed an atomic-level NiO–In2O3 heterojunction and explored its adsorption behaviors and sensing properties for CO and H2 by first-principles calculations. Analysis of its electronic properties, focusing on binding energy, differential charge density, and density of states, confirmed the creation of a highly stable NiO–In2O3 heterojunction and alterations in the coordination environment of the surface-active atoms. These changes potentially led to differences in the affinity between the gas molecules and the adsorption sites. The calculations of the adsorption properties revealed that the adsorption capacity of H2 is relatively weak compared to the strong interactions between CO and heterojunction surface atoms, indicating a readily variable reaction pathway for H2. Consequently, the adsorption configuration at the interface site on the NiO–In2O3 heterojunction surface exhibited a predominantly p-type response for CO and a unique n-type response for H2. This interfacial effect of the heterojunction is crucial for the selective adsorption of CO and H2. Furthermore, the opposite response signal was verified by gas sensing tests, which also presented the superior stability of the NiO–In2O3 sensor. The p–n heterojunction of the corresponding composites was effectively characterized. This research offers new insights into the selective adsorption mechanism, paving the way for the development of gas sensors.

The selective adsorption mechanism of benzene over water on nitrogen-doped activated carbon regulated by methyl functional groups

Improving the adsorption capacity of activated carbon (AC) for volatile organic compounds (VOCs) in humid conditions, while suppressing the interference of water molecules on the adsorption process, is significant for maximizing the effectiveness of AC as an adsorbent for efficient VOC removal. This paper investigates the impact of water on benzene adsorption by nitrogen-doped activated carbon (ACN), the hydrophobicity of different nitrogen-doped types, and the effects of methyl on the selective adsorption of benzene by ACN. The investigation is based on experiments and DFT simulations, and the corresponding mechanisms were elucidated through the force field-based energy decomposition analysis (EDA-FF), the independent gradient model based on Hirshfeld partition (IGMH), and the atoms in molecules (AIM). Under the coexistence of benzene and water, a van der Waals (vdW) interaction occurs between the adsorbed water molecules and benzene molecules, which seriously impairs benzene adsorption on ACN. Pyridine and pyrrole N enhance the adsorption of water by increasing the electrostatic interaction between water molecules and AC. Methyl group reduces hydrophilicity by increasing the repulsion of pyridine and pyrrole nitrogen with water. The selective adsorption of benzene on ACN was improved by enhancing the dispersion effect with benzene. The experimental results showed that after ACN modification with the methyl, benzene adsorption was completely restored to the situation when there was no water interference. This confirms that nitrogen-methylation is an effective method for enhancing benzene adsorption by AC while suppressing water interference.

An in-depth exploration of the impact of novel collector HPDDA on the low-temperature flotation behavior of bastnaesite and quantum chemical calculation

Traditional cationic collectors commonly suffer from drawbacks such as poor solubility and low-temperature resistance, which impede the effectiveness of flotation. Hence, this study designed and synthesised a novel collectors, 2-Hydroxypropane-1,3-bis(dodecyl dimethyl ammonium) bromide (HPDDA), tailored for low-temperature flotation of bastnaesite. The positive charges of the surface molecular electrostatic potential (ESP) of HPDDA concentrate near the two quaternary ammonium groups, with minimal points also appearing between the two N atoms. Near the quaternary ammonium groups, weak van der Waals (vdW) and spatial hindrance occur due to the abundance of polar groups. The Krafft point test reveal that the Krafft point of HPDDA was below 0 °C, significantly higher than that of DDA. HPDDA exhibited excellent pH adaptability and cold resistance, demonstrating outstanding selective capturing capability for bastnaesite even at low temperatures, thereby enabling the separation of bastnaesite from calcite. Analysis through various detection methods such as zeta potential, Fourier transform infrared (FT-IR), contact angle measurement, and X-ray photoelectron spectroscopy (XPS) elucidates the selective adsorption mechanism of HPDDA on the surface of bastnaesite, attributing it to the differences in surface electrification and other properties between bastnaesite and calcite. This work provides new collector and theoretical guidance for solving the low-temperature flotation of bastnaesite.

Selective Adsorption of Hazardous Substances from Wastewater by Hierarchical Oxide Composites: A Review.

Large volumes of wastewater containing toxic contaminants (e.g., heavy metal ions, organic dyes, etc.) are produced from industrial processes including electroplating, mining, petroleum exploitation, metal smelting, etc., and proper treatment prior to their discharge is mandatory in order to alleviate the impacts on aquatic ecosystems. Adsorption is one of the most effective and practical methods for removing toxic substances from wastewater due to its simplicity, flexibility, and economics. Recently, hierarchical oxide composites with diverse morphologies at the micro/nanometer scale, and the combination advantages of oxides and composite components have been received wide concern in the field of adsorption due to their multi-level structures, easy functionalization characteristic resulting in their large transport passages, high surface areas, full exposure of active sites, and good stability. This review summarizes the recent progress on their typical preparation methods, mainly including the hydrothermal/solvothermal method, coprecipitation method, template method, polymerization method, etc., in the field of selective adsorption and competitive adsorption of hazardous substances from wastewater. Their formation processes and different selective adsorption mechanisms, mainly including molecular/ion imprinting technology, surface charge effect, hard-soft acid-base theory, synergistic effect, and special functionalization, were critically reviewed. The key to hierarchical oxide composites research in the future is the development of facile, repeatable, efficient, and scale preparation methods and their dynamic adsorption with excellent cyclic regeneration adsorption performance instead of static adsorption for actual wastewater. This review is beneficial to broaden a new horizon for rational design and preparation of hierarchical oxide materials with selective adsorption of hazardous substances for wastewater treatment.

Selective adsorption mechanism of polyoxyethylene alkyl amine in reverse flotation separation of fayalite and magnetite without depressant

Effective flotation separation of magnetite from iron-bearing silicate minerals is difficult with conventional collectors because of their similar surface properties. In this work, polyoxyethylene alkyl amine (PAE), which is easy to prepare and has high surface activity, was used for the reverse flotation separation of fayalite and magnetite for the first time, and its selective adsorption mechanism was revealed. The micro-flotation tests results show that compared with dodecylamine (DDA), the separation effect of PAE on fayalite and magnetite was significantly improved. When pH was 6.5 and PAE dosage was 20 mg/L, the selective separation of fayalite and magnetite can be achieved by reverse flotation without depressant. The results of zeta potential and contact angle measurement shown that PAE was significantly adsorbed on fayalite compared with magnetite, so the hydrophobicity of fayalite treated by PAE was effectively enhanced. In addition, the differential adsorption of PAE on fayalite and magnetite was further verified by Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS) and molecular dynamics (MD) simulation, where PAE was adsorbed on the surface of fayalite by electrostatic adsorption and hydrogen bonding, while electrostatic repulsion caused PAE to be removed from the surface of magnetite. The angle between the ethylene oxide chains of PAE at adsorption equilibrium reflects the stress state of NH+ and –OH. Therefore, the selective flotation separation of magnetite and fayalite was realized based on the electrical difference of mineral surface and PAE structural characteristics.

Study on the effects of a novel imidazoline siliconophilic collector in the desilication process of magnesite: Separation experiments, adsorption mechanisms, and separation model

This study innovatively introduced heptadecenyl amine ethyl imidazoline quaternary ammonium salt (ODD) as a siliconophilic flotation collector, effectively facilitating the achievement of high-efficiency separation of magnesite from quartz. ODD exhibits unique properties such as high selectivity and environmental friendliness. Through a comprehensive series of experiments, including flotation tests, zeta potential characterization, atomic force microscopy (AFM) imaging, Fourier-transform infrared (FTIR) spectroscopy, and time-of-flight secondary ion mass spectrometry (ToF-SIMS), the flotation performance and selective adsorption mechanisms of ODD were thoroughly investigated. The experiments demonstrated that at a pH of 7.00 and an ODD concentration of 40 mg/L, quartz achieved a flotation recovery rate of 95.16 %, while magnesite was only 2.99 %, underscoring the high selectivity of ODD in mineral separation. Zeta potential measurements indicated that ODD exhibits strong adsorption interactions with quartz over magnesite. AFM observations confirmed that ODD forms significant adsorption structures on quartz surfaces, in contrast to weaker interactions with magnesite. FTIR analysis further revealed the robust interactions between ODD and quartz through hydrogen bonds and electrostatic forces, which were significantly diminished on magnesite surfaces. ToF-SIMS analysis provided direct evidence of ODD’s selective adsorption on quartz, contributing to a better understanding of the flotation mechanisms involved. This research not only offers a novel approach for the purification of magnesite and effective removal of quartz but also demonstrates the potential of ODD as an eco-friendly collector in mineral processing, potentially advancing a green transformation in the industry. The findings provide a solid theoretical and experimental basis for future industrial applications and innovative development of flotation collectors.

Selective Adsorbent Design with Multifunctional Surfaces: Innovating Solutions for Heterogeneous Catalysis in Water.

Heterogeneous catalytic systems with water as the solvent often have the disadvantage of cross-contamination, while concerns about the purification and workup of the aqueous phase after reactions are rare in the lab or industry. In this context, designing and developing the functional selective solid adsorbent and revealing the adsorption mechanism can provide a new strategy and guidelines for constructing supported heterogeneous catalysts to address these issues. Herein, we report the stable composite adsorbent (Fe/ATP@PPy: magnetic Fe3O4/attapulgite with the polypyrrole shell) that features an integrated multifunctional surface, which can effectively tune the selective adsorption processes for Cu2+, Co2+, and Ni2+ ions and nitrobenzene via the cooperative chemisorption/physisorption in an aqueous system. The adsorption experiments showed that Fe/ATP@PPy displayed significantly higher adsorption selectivity for Ni2+ than Cu2+ and Co2+ ions, especially which exhibited an approximate 100.00% removal for both Ni2+ ions and nitrobenzene in the mixture system with a low concentration. Furthermore, combined tracking adsorption of Ni2+ ions and X-ray photoelectron spectroscopy characterization confirmed that the effective adsorption occurs via ion transfer coordination; the pathway was further validated at the molecular level through theoretical modeling. In addition, the selective adsorption mechanism was proposed based on the adsorption experiment, characterization, and the corresponding density functional theory calculation.

Highly selective PAN@MOFs composite nanofiber for removal of C4F7N/CO2 harmful decomposition products

Perfluoroisobutyronitrile (C4F7N) mixed with CO2 has emerged as a promising eco-friendly alternative to sulfur hexafluoride (SF6) in gas-insulated equipment (GIE). However, thermal or discharge faults in GIE inevitably lead to the generation of harmful decomposition by-products, necessitating their prompt removal to safeguard equipment operation and personnel safety. In this study, we propose a nanofiber composite material comprising polyacrylonitrile (PAN) as the base and multi-metal organic frameworks (MOFs) as the primary adsorbent material for removing typical decomposition components of C4F7N/CO2 gas mixture. Utilizing grand canonical Monte Carlo (GCMC) and molecular dynamics (MD) simulations, we elucidate the selective adsorption mechanisms. Experimental results show that PAN@HKUST-1(Cu) exhibits superior adsorption efficiency for fluorocarbon gases compared to PAN@MIL-101(Cr), while the latter demonstrates better performance for nitrile gases. The PAN@HKUST-1(Cu)/MIL-101(Cr) composite adsorbent effectively removes eight typical harmful decomposition products while minimally affecting C4F7N. Our findings suggest that PAN@HKUST-1(Cu)/MIL-101(Cr) nanofiber film holds promise as an adsorbent for C4F7N/CO2 based GIE.

Chitosan-vermiculite composite adsorbent: Preparation, characterization, and competitive adsorption of Cu(II) and Cd(II) ions

The cost-effective removal of heavy metal ions represents a significant challenge in environmental science. In this study, we developed a straightforward and efficient reusable adsorbent by amalgamating chitosan and vermiculite (forming the CSVT composite), and comprehensively investigated its selective adsorption mechanism. Different techniques, such as Fourier-transform infrared spectroscopy (FTIR), zeta potential analysis, scanning electron microscopy (SEM), X-ray diffraction (XRD), and Brunauer, Emmett, Teller (BET) analysis were employed for this purpose. The prepared CSVT composite exhibited a larger surface area and higher mesoporosity increasing from 1.9 to 17.24 m2/g compared to pristine chitosan. The adsorption capabilities of the CSVT composite and pristine chitosan for Cu(II) and Cd(II) species were systematically examined. Due to its porous structure and increased surface area, the CSVT composite demonstrated superior adsorption ability when compared to pristine chitosan. The maximum adsorption capacities of Cu(II) and Cd(II), determined by Langmuir adsorption isotherms in batch experiments, were found to be 116.22 and 147.64 mg/g, respectively, under initial pH conditions of 8 and an initial concentration of 250 mg/L. The thermodynamic analysis revealed that the adsorption process for both metal ions is spontaneous, endothermic physisorption, and thermodynamically favorable. These findings collectively affirm the CSVT composite as a highly promising adsorbent for the efficient and selective removal of Cu(II) and Cd(II) from aqueous solutions.