Influence of synthesis conditions on the production of molecularly imprinted polymers for the selective recovery of isovaleric acid from anaerobic effluents

Two molecularly imprinted polymers (MIPs) – poly(methacrylic acid‐co‐TRIM) (TRIM, trimethylolpropanetrimethacrylate) and poly(acylamide‐co‐TRIM) – were synthesized in different solvents for the selective recovery of isovaleric acid (template) generated during the anaerobic digestion process. The chemical and structural characterizations of the synthetic adsorbent were carried out by Fourier transform infrared spectroscopy, TGA and porosimetry through N₂ adsorption–desorption isotherms. The selective and adsorptive performances of the imprinted polymers were evaluated by kinetic, isothermal, thermodynamic and selectivity studies and by adsorbent reuse experiments. The poly(methacrylic acid‐co‐TRIM) synthesized with dimethyl sulfoxide:chloroform presented higher selectivity and adsorption capacity for isovaleric acid in the presence of six volatile fatty acids. The kinetic results were well adjusted to the pseudo‐nth order and intraparticle diffusion models, leading to k values of 10^?4 and 6 × 10^?5 for the best synthesis of MIPs and not‐imprinted polymers, respectively. Moreover, the Sips model best described the adsorption isotherm and generated a maximum adsorption capacity of ca 209 mg g^?1 (at 25 °C). Cycles of MIP use–desorption–reuse indicated that the selective adsorbent performed better than commercial adsorbents, losing less than 3% of adsorption capacity after three cycles. © 2018 Society of Chemical Industry     

Adsorption of Pb2+, Cu2+ and Co2+ by polypropylene fabric and polyethylene hollow fiber modified by radiation-induced graft copolymerization

Cation-exchange adsorbents were prepared by radiation-induced grafting of glycidyl methacrylate (GMA) onto polypropylene (PP) fabric and polyethylene (PE) hollow fiber and subsequent phosphonation of epoxy groups of poly(GMA) graft chains. The adsorption characteristics of Pb²⁺, Cu²⁺ and Co²⁺ for the two cation-exchange adsorbents were studied. In the grafting of GMA onto PP fabric, the degree of grafting (%) increased with an increase in reaction time, reaction temperature, and pre-irradiation dose. The maximum grafting yield was observed around 60% GMA concentration. In 50, 130 and 250% GMA-grafted PP fabric, the content of phosphoric acid was 1.52, 3.40 and 4.50 mmol/g at 80 °C in the 85 % phosphoric acid aqueous solution for 24 h, respectively. The adsorption of Pb²⁺, Cu²⁺ and Co²⁺ by PP fabric adsorbent was enhanced with an increased phosphoric acid content The order of adsorption capacity of the PP fabric adsorbent was Pb²⁺>Co²⁺>Cu²⁺. In adsorption of Pb²⁺, Cu²⁺ and Co²⁺ by PE hollow fiber, the amount of Pb²⁺ adsorbed by the PE hollow fiber adsorbent containing 1.21 mmol/g of -PO₃H wasca. 54.4 g per kg. The adsorption amount of Cu²⁺ and Co²⁺ in the same PE hollow fiber wasca. 21.0 g per kg andca. 32.1 g per kg, respectively. The order of adsorption of the PE hollow fiber adsorbent was Pb²⁺>Co²⁺>Cu²⁺.     

Adsorptive removal of fluoride from water by activated carbon derived from CaCl2-modified Crocus sativus leaves: Equilibrium adsorption isotherms,optimization, and influence of anions

A central composite design using response surface methodology was applied for the experimental design and optimization of fluoride adsorption on an activated carbon derived from calcium chloride-modified Crocus sativus leaves (AC-CMCSL). Fluoride removal efficiency as function of independent variables, such as initial fluoride concentration, pH, adsorbent dose, and time has been investigated. The maximum percentage removal of fluoride at optimum conditions (initial fluoride concentration?=?6.5?mg?L^?1, pH?=?4.5, adsorbent dose?=?15?g?L^?1 and time?=?70?min) was 85.43%. By comparing adsorption isotherm, the Freundlich model provided the best correlation (R²?=?0.99) for the adsorption of fluoride on AC-CMCSL. The maximum adsorption capacity from the Langmuir model (q_max) was 2.01?mg?g^?1. The influence of the co-existing anions on fluoride adsorption was in the following order: PO₄^3??>?SO₄^2??>?Cl^??>?NO₃^?. The results of the present study showed that activated carbon derived from the leaves of calcium chloride-modified Crocus sativus has a good potential for fluoride removal from aqueous solution.     

Improved synthesis of a branched poly(ethylene imine)‐modified cellulose‐based adsorbent for removal and recovery of Cu(II) from aqueous solution

This study focuses on an improved synthesis of a branched poly (ethylene imine) (PEI)‐modified cellulose‐based adsorbent (Cell‐g‐PGMA‐PEI). We aim to improve the adsorbent capacity by reducing side reaction of epoxide ring opening during graft copolymerization of glycidyl methacrylate (GMA) onto cellulose which increases the content of epoxy groups, anchors to immobilize branched PEI moieties. FTIR spectra provided the evidence of successful graft copolymerization of GMA onto cellulose initiated by benzoyl peroxide (BPO) and modification with PEI. The amount of epoxy groups of Cell‐g‐PGMA was 4.35 mmol g^?1 by epoxy titration. Subsequently, the adsorption behavior of Cu(II) on cell‐g‐PGMA‐PEI in aqueous solution has been investigated. The data from the adsorption kinetic experiments agreed well with pseudo‐second‐order model. The adsorption isotherms can be interpreted by the Langmuir model with the maximum adsorption capacity of 102 mg g^?1 which was largely improved compared with the similar adsorbent reported. The dynamic adsorption capacity obtained from the column tests was 119 mg g^?1 and the adsorbent could be regenerated by HCl of 0.1 mol L^?1. Results indicate that the novel pathway for the synthesis of Cell‐g‐PGMA‐PEI exhibits significant potential to improve the performance of adsorbents in removal and recovery of Cu(II) from aqueous solution. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Commercial Diatomite for Adsorption of Tetracycline Antibiotic from Aqueous Solution

Extensive use of antibiotics in human therapy and farming industry has resulted in their accumulation and potential hazards to the environment. In this study, diatomite, which is a siliceous rock with large surface area and high adsorptivity towards organic compounds, was used to adsorb the antibiotic tetracycline (TC) from aqueous media. The adsorption kinetics, isotherms, thermodynamics, and effects of the adsorbent amount and ionic strength were evaluated in batch adsorption experiments. The adsorption of TC onto diatomite followed the pseudo-second-order kinetics model, and the sorption equilibrium was reached in 120 min. The perfect adsorbent amount could be selected within the range of 1 ? 20 g·L^?1. The equilibrium data at different temperatures was satisfactorily fitted to the Langmuir isotherm equation with high R² above 0.999, and the maximum monolayer adsorption capacity of 303.03 mg·g^?1 was obtained at 318 K using 1 g·L^?1 diatomite. Thermodynamic parameters showed that the adsorption reaction was spontaneous and endothermic. Moreover, the adsorption of TC was insignificantly affected by the ionic strength of 0.05-1% NaCl and CaCl₂, indicating that diatomite has a potential practical application as adsorbent media for removing TC from real water.     

Studies on two‐dimensional coordination polymer cadmium phosphate and its high efficient adsorption of Pb(II) ions from aqueous solutions

The two‐dimensional coordination polymer cadmium phosphate with the morphology of rectangle layers was prepared by solid‐state template reaction at room temperature, and was characterized by XRD, FTIR, and TEM techniques. The as‐synthesized sample is a layered cadmium phosphate material, in which the structure is poly (CdPO₄^?) anion framework with ammonium ions and water species residing in the space between the layers, and cadmium ions are coordinated by the phosphate oxygen atoms. This article also presents the adsorption of Pb(II) ions from aqueous solution on the as‐synthesized coordination polymer cadmium phosphate, and the results showed that this inorganic polymer adsorbent had good adsorption capacity. It could reach to the saturation adsorption capacity within an hour, and its excellent adsorption capacity for Pb(II) was 5.50 mmol/g when the initial solution concentration was 1.68 × 10³ μg/mL at T = 278K. Moreover, the adsorption kinetics and adsorption isotherms were studied, it revealed that the adsorption kinetics can be modeled by pseudo second‐order rate equation wonderfully. The apparent activation energy (E_a), ΔG, ΔH, and ΔS were 3.16 kJ mol^?1, ?13.97 kJ mol^?1, ?11.84 kJ mol^?1, and 7.66 J mol^?1 K^?1, respectively. And it was found that Langmuir equation could well interpret the adsorption of the as‐synthesized coordination polymer cadmium phosphate for Pb(II) ions. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Adsorption of fulvic acids from aqueous solutions by carbon nanotubes

Carbon nanotubes (CNTs) were used as adsorbent to remove fulvic acids (FA) from aqueous solutions. The adsorption capacity of CNTs for FA can reach 24 mg g^?1 at 5 °C and equilibrium concentration of 18 mg dm^?3. The kinetic and thermodynamic parameters, such as rate of adsorption, standard free energy changes (ΔG⁰), standard enthalpy change (ΔH⁰) and standard entropy change (ΔS⁰), have been obtained. Acidic conditions (pH = 2–5) favor FA removal. An increase in the ionic strength or the addition of divalent cations increase the adsorption of FA dramatically (FA = 60 mg dm^?3). An increase in the maximum adsorbed amount of FA was observed when treating FA in synthetic seawater. Desorption studies reveal that FA can be easily and quickly removed from CNTs by altering the pH values of the solution. Good adsorption capacity and quick desorption indicate that CNTs are a promising adsorbent to remove FA from aqueous solutions. Copyright © 2007 Society of Chemical Industry     

Application of magnetite modified with aluminum/silica to adsorb phosphate in aqueous solution

BACKGROUND: Phosphate is one of the main contaminants responsible for the eutrophication of surface waters, and adsorption is a potential treatment method for this pollutant. A magnetic adsorbent manufactured from magnetite (Fe₃O₄) can be recovered easily from treated water by magnetic force, without requiring further downstream treatment. In this research, the surface of magnetite modified with aluminum and silica (Al/SiO₂/Fe₃O₄) was used to adsorb phosphate in an aqueous solution in a batch system. RESULTS: The optimum solution pH for phosphate adsorption by Al/SiO₂/Fe₃O₄ was found to be 4.5. The phosphate adsorption behavior of Al/SiO₂/Fe₃O₄ was in good agreement with both the Langmuir and Freundlich adsorption isotherm, and the maximum adsorption capacity (q_m) and Gibbs free energy of phosphate was 25.64 mg g^?1 and ? 21.47 kJ mol^?1, respectively. A pseudo‐second‐order model could best describe the adsorption kinetics, and the derived activation energy was 3.52 kJ mol^?1. The optimum condition to desorb phosphate from Al/SiO₂/Fe₃O₄ is provided by a solution with 0.05 mol L^?1 NaOH. CONCLUSIONS: Magnetic adsorbent is a potential material for a water treatment method. The results of this study will be helpful in the development of aluminum modified silica magnetic adsorbents that can be used to remove phosphate in aqueous solution. Copyright © 2011 Society of Chemical Industry     

Removal of Pb(II) from aqueous solutions by adsorption onto clayey soil of Indian origin: Equilibrium, kinetic and thermodynamic profile

The feasibility of applying natural, untreated clayey soil as low-cost alternative adsorbent for Pb(II) removal from aqueous solutions was investigated with a batch experimental set-up. Experiments were carried out as a function of initial solution pH (1?C8), contact time (10?C360 min), initial Pb(II) concentration (20?C100 mg L^?1), adsorbent dose (0.5?C5 g) and temperature (303?C333 K). Adsorption equilibrium data were well described by the Langmuir isotherm with maximum adsorption capacity of 121.86 mg g^?1 at 303 K. Adsorption of Pb(II) followed pseudo-second-order kinetics. Gibbs free energy (??G⁰) was spontaneous for all interactions, and the adsorption process exhibited exothermic enthalpy values. The adsorbent was easily regenerated by using 0.1M HNO₃ solution and was reused for five sorptiondesorption cycles without any considerable loss in adsorption capacity. It could be concluded that clayey soil may be used as an inexpensive and effective adsorbent without any treatment or any other modification for the removal of Pb(II) ions from aqueous solutions.     

Analysis of intraparticle diffusion on adsorption of crystal violet on bentonite

Abstract

In the present work, kinetics of crystal violet (CV) adsorption on bentonite was studied by pore volume and surface diffusion model (PVSDM), surface diffusion model (SDM), and pore volume diffusion model (PVDM). The adsorption decay curves were obtained in batch system using different adsorbent dosages. The PVDM model did not interpreted the kinetic adsorption since the calculated value of D_p equal to 5.64?×?10^?7 cm² s^?1 predicted a slower adsorption than that obtained by the experimental data. The PVSDM results indicates that the intraparticle diffusion is predominantly due to surface diffusion (93%) and the pore volume diffusion can be negligible. Once the surface diffusion was the limiting step, the estimation with one (D_s) and two (D_sq and α) parameters were tested in the SDM model. The statistical analysis revealed that the one-parameter SDM model was most appropriate to predict the CV adsorption on bentonite. The optimal values of Ds ranged from 6.19?×?10^?10 to 6.49?×?10^?10 cm² s^?1, and decrease with the adsorbent dosage.     

Facile synthesis of imprinted submicroparticles blend polyvinylidene fluoride membranes at ambient temperature for selective adsorption of methyl <Emphasis Type="Italic">p</Emphasis>-hydroxybenzoate

We developed a simple phase inversion technique to prepare molecularly imprinted membrane (MIM) at room temperature for membrane selective adsorption and separation of methyl p-hydroxybenzoate (M4HB). The prepared SMIP-MIM was characterized by SEM, FT-IR, TGA. Compared with non-imprinted membrane (NIM_1-5) adsorbent, SMIP-MIM_1-5 adsorbent with high specific surface area and showed higher binding capacity, faster kinetic and better selectively adsorption capacity for M4HB. The maximum isotherm adsorption capacity for M4HB of SMIP-MIM₄ was 3.519mg·g^?1, and the experimental data was well fitted to the slips model by multiple analysis. The maximum kinetic adsorption capacity and equilibrium adsorption time for SMIP-MIM₄ were 1.335mg·g^?1 and 160 min, respectively. The mechanism for dynamic adsorption of M4HB onto SMIP-MIM₄ was found to follow pseudo-first-order model and pseudo-second-order model. Additionally, the permeability separation factor of SMIP-MIM₄ for M4HB compared to a structural analogues methyl 2-hydroxybenzoate (M2HB) could reach 2.847. The adsorption capacity of SMIP-MIM₄ for M4HB and M2HB was 0.549mg·cm^?2 and 1.563mg·cm^?2, respectively. The adsorption behavior of M4HB through SMIP-MIM₄ followed the retarded permeation mechanism.     

A diamino based resin modified silica composite for the selective recovery of tungsten from wastewater

A new adsorbent was developed by synthesizing 1,8‐diaminonaphthalene formaldehyde resin (DANFR) and coating it over the surface of silica gels. The silica composite was then treated with HCl for the activation of binding sites (?NH₃⁺Cl^?) on its surface. The structure of DANFR and its coating over the silanols were thoroughly characterized. Further, the adsorbent was applied to remove tungsten (W) from printed circuit board recycling unit wastewater that contained various co‐metal ions such as Na⁺, K⁺, Ca²⁺, Mg²⁺, Pb²⁺, NH₄⁺, Zn²⁺, Cu²⁺ and Mn²⁺. The selective removal was achieved due to the anion exchange mechanism of Cl^? with W(VI) while other cations get repelled from the surface (?NH₃⁺) of the DANFR‐silica composite. X‐ray photoelectron spectroscopy studies, Raman spectra and overlay chromatograms of ion chromatography demonstrated selective separation of WO₄^2? species from the wastewater. A removal capacity of 55.32 mg g^?1 for W(VI) was achieved from the wastewater within 45 min of reaction (pH ca 6.0). Simultaneous treatment with neat aqueous solution of W brings out 63.27 mg g^?1 of W(VI) removal. Finally, recovery of WO₄^2? ions and regeneration of the adsorbent were carried out by using alkaline solution which demonstrated successful desorption, as investigated by using ion chromatography. © 2016 Society of Chemical Industry     

Surface modification of rubber (Hevea brasiliensis) leaves for the adsorption of copper ions: kinetic,thermodynamic and binding mechanisms

BACKGROUND: This research describes the adsorption of copper ions from aqueous solutions following the modification of rubber (Hevea brasiliensis) leaves with formaldehyde solution. The main objectives of this research were to identify the binding mechanisms of copper ions on the chemically modified rubber leaves by spectroscopic techniques and to investigate the effects of several important physicochemical parameters such as pH, copper concentration, contact time, adsorbent dose and temperature on copper removal. RESULTS: Based on a kinetic study, the pseudo‐second‐order model was found to fit the experimental results well, while the Boyd kinetic model indicated that the rate‐determining step was due to film diffusion. Adsorption isotherms were modelled by the Langmuir and Freundlich isotherm equations, with the former providing a better fit for the data. Based on the Langmuir model, the maximum adsorption capacities of Cu(II) ions at 300, 310 and 320 K were 8.36, 8.61 and 8.71 mg g^?1, respectively. Thermodynamic parameters such as the Gibbs free energy (ΔG°), enthalpy (ΔH°) and entropy changes (ΔS°) were calculated. The adsorption process was spontaneous as the values of ΔG° were negative, and endothermic as higher adsorption capacities were recorded at higher temperatures. More than 80% of copper ions bound on the adsorbent were able to be desorbed using 0.02 mol L^?1 HCl, HNO₃ and EDTA solutions. Besides ion exchange, surface complexation could also play a major role in copper binding. CONCLUSION: Due to its relative abundance and satisfactory adsorption capacity, the modified rubber leaves can be considered as a good low‐cost adsorbent for removing copper ions from dilute aqueous solutions. Copyright © 2008 Society of Chemical Industry     

Removal of Crystal Violet Dye from Aqueous Solution Using Calcined and Uncalcined Mixed Clay Adsorbents

In this work, calcined and uncalcined mixed clays containing kaolin, ball clay, feldspar, pyrophyllite, and quartz are examined as a potential adsorbent for the removal of crystal violet dye from aqueous solution. These clays are characterized by nitrogen adsorption/desorption isotherms, X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and thermo gravimetric analysis (TGA). The kinetics and thermodynamic parameters as well as the effects of the pH, the temperature, and the adsorbent dosage have also been investigated. The experimental results indicate that the Langmuir model expresses the adsorption isotherm better than the Freundlich model. The obtained result showed a tremendous increase in the crystal violet adsorption capacity (1.9 × 10^?3 mol g^?1) after calcination, which is one order greater than that of the uncalcined mixed clay. The mechanism of the adsorption process is elucidated on the basis of experimental data. The percentage removal of crystal violet dye increases with increasing the pH, the temperature, and the adsorbent dosage. The investigation of kinetic studies indicates that the adsorption of crystal violet on calcined and uncalcined mixed clays could be described by the pseudo-second-order model. The negative Δ G ⁰ values obtained from the thermodynamic investigation confirm that the adsorption is spontaneous in nature. The adsorption results suggest that the calcined and uncalcined mixed clays can also be used as low cost alternatives to the expensive activated carbon for the removal of dyes from aqueous solution.     

Adsorption of bismuth(III) by bayberry tannin immobilized on collagen fiber

The adsorption behavior of collagen fiber‐immobilized bayberry tannin towards Bi(III) at acidic pH values was investigated. The adsorption capacity of the adsorbent towards Bi(III) was 0.348 mmol g^?1 at 303 K, and increased with the rise in temperature. The adsorption isotherms of Bi(III) were in the shape of so‐called type II isotherms and could be described by an empirical equation, ln q_e = k + (1/n)C_e, which implies that chemical adsorption is predominant at lower concentrations of Bi(III) and that physical adsorption is involved at higher concentrations. The adsorption kinetics of Bi(III) on the immobilized bayberry tannin could be well described by the pseudo‐second‐order rate model, and the adsorption capacities calculated by the model were almost the same as those determined by actual measurements. The adsorbent could be regenerated by using 0.02 mol dm^?3 ethylenediaminetetraacetic acid (EDTA) solution after adsorption of Bi(III). The adsorption selectivity of the immobilized bayberry tannin towards Bi(III) in a Cu(II)–Bi(III) binary solution in acidic medium was remarkable. Therefore, it is strongly suggested that the immobilized bayberry tannin could be applied to the removal of Bi(III) from crude Cu(II) samples under proper conditions. Copyright © 2006 Society of Chemical Industry     

Adsorption of Cu2+ Cations from Aqueous Solution by S-doped TiO2

S-doped TiO₂ as a novel adsorbent for Cu²⁺ cations removal from aqueous solutions was synthesized by simple sol-gel process. Removal of Cu²⁺ cations from aqueous solutions was investigated with particular reference to the effects of initial Cu²⁺ cations concentration, pH-value, adsorbent dosage, and temperature on adsorption. It was found that the maximum adsorption capacity was 96.35 mg g^?1 at 328 K. The adsorption equilibrium isotherms and the kinetic data were well described by the Langmuir and pseudo-second-order kinetic models, respectively. The high uptake capability of S-doped TiO₂ makes it a potentially attractive adsorbent for the removal of heavy metal pollutants from aqueous solution.     

Synthesis of Fe2O3-coated and HCl-treated bauxite ore waste for the adsorption of arsenic (III) from aqueous solution: Isotherm and kinetic models

The present work has focused on the removal of arsenic (III) using two effective adsorbents such as red mud treated with HCl and coated with Fe₂O₃. Adsorption of As (III) was performed by the function of pH, adsorbent dose, contact time, initial ion concentration, and the appropriate conditions for adsorption were determined. The characterization studies of the adsorbent were analyzed using X-ray diffraction, X-ray fluorescence, Brauner–Emmett–Teller, scanning electron microscope, and FTIR spectroscopy. The result of the studies shows that the adsorbent is suitable for the effective removal of As (III) ions. Batch adsorption process showed that the maximum adsorption occurred at Fe₂O₃-coated red mud. The equilibrium data were well fitted to the nonlinear Langmuir isotherm model and the maximum adsorption capacity (q_m) of Fe₂O₃-coated red mud was found to be 21.85?mg?g^?1 which indicates that Fe₂O₃-coated red mud had more adsorption capacity. In the Freundlich isotherm, the experimentally obtained n value of Fe₂O₃-coated red mud was 2.393 which indicates the favorable adsorption of As (III) on the adsorbent. Dubinin–Radushkevich isotherm confirms that the adsorption process is physical in nature. Furthermore, the adsorption kinetic studies followed the pseudo-first-order model. All the results concluded that Fe₂O₃-coated red mud can be considered as a cost-effective and potential adsorbent for As (III) removal.     

Preparation and characterization of selective phenyl thiosemicarbazide modified Au(III) ion‐imprinted cellulosic cotton fibers

In this study, a novel selective Au(III) chelating surface ion imprinted fibers based on phenyl thiosemicarbazide modified natural cotton (Au‐C‐PTS) has been synthesized, and applied for selective removal of Au(III) from aqueous solutions. Batch adsorption experiments were performed with various parameters, such as contact time, pH, initial Au(III) concentration, and temperature. The kinetic studies revealed that the adsorption process could be described by pseudo‐second‐order kinetic model, while the adsorption data correlated well with the Langmuir and Freundlich models. The maximum adsorption capacities calculated from the Langmuir equation are 140 ± 1 mg g^?1 and 72 ± 1 mg g^?1 at pH 5 for both Au‐C‐PTS and NI‐C‐PTS, respectively. The estimated thermodynamic parameters (Gibbs free energy (ΔG°), enthalpy (ΔH°), and entropy change (ΔS°)) indicated the spontaneity and exothermic nature of the adsorption process. Furthermore, the selectivity study revealed that the ion imprinted fibers was highly selective to Au(III) compared with Cu(II), Cd(II), Hg(II), and Fe(III). The adsorbent was successfully regenerated with a 0.1M HNO₃ solution. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40769.     

Adsorptive removal of cationic dye from aqueous solutions by ZnO/ZnMn2O4 nanocomposite

The ZnO/ZnMn₂O₄ nanocomposite (ZnMn) was used as adsorbent for the removal of cationic dye Basic Yellow 28 (BY28) from aqueous solutions. The adsorbent was characterized by X-ray diffraction, scanning electron microscope, TEM, Fourier transform infrared ray, BET, particle size distribution and zeta potential measurements. The adsorption parameters, such as temperature, pH and initial dye concentration, were studied. Kinetic adsorption data were analyzed using the pseudo-first-order, pseudo-second-order and intraparticle diffusion kinetic models. The Langmuir and Freundlich isotherm models were applied to fit the equilibrium data. The maximum adsorption capacity of BY28 was 48.8 mg g^?1. Various thermodynamic parameters, such as ΔG°, ΔH° and ΔS°, were calculated.     

A Non-Conventional Adsorbent for the Removal of Clofibric Acid from Aqueous Phase

The adsorption of Clofibric acid, one of the most frequently prescribed high environmental risk drugs, was studied using H₃PO₄ activated Schumannianthus dichotomus (ASD). The chemical characteristics of the adsorbent were established by Bohem’s titration, pH_PZC, FTIR, SEM, XRD, porosity, and surface area analysis. It was observed that the adsorbent was microporous-mesoporous in nature with BET surface area of 1199.98 m².g^?1. The influence of temperature (303-323 K), pH (2-10), textural properties, adsorbent load, and contact time was studied. The Langmuir equation was found to best represent the equilibrium data for clofibric acid-adsorbent system, yielding monolayer adsorption capacity of 258.39 mg.g^?1 at 303 K. The pseudo-second order model best explained (R² > 0.999) the adsorption kinetics with rate constant 0.037 g.mg^?1min^?1. The thermodynamics parameters, ΔG°, ΔH°, and ΔS°, evaluated as ?8.14 kJmol^?1, ?34.07 kJmol^?1, and ?85.5 JK^?1mol^?1, respectively, revealed that the adsorption process is feasible, spontaneous, and exothermic in nature. In the column mode, the adsorption capacity of ASD (267.93 mg.g^?1) was found to be higher than the batch mode of operation (258.39 mg.g^?1). The cost incurred per kg of the developed adsorbent was USD 14.36.