Biosorption of methylene blue from aqueous solution by softstem bulrush (Scirpus tabernaemontani Gmel.)

BACKGROUND: The removal of methylene blue from aqueous solution was studied using softstem bulrush (Scirpus tabernaemontani Gmel.) as the biosorbent. The effects of various parameters including contact time, biosorbent dosage, ionic strength and solution pH on the biosorption were investigated. RESULTS: The sorption capacity increased with an increase in biosorbent dosage and a decrease in ionic strength. The equilibrium time was found to be 240 min for full equilibration. Pseudo‐first‐order, pseudo‐second‐order, Bangham equation and intraparticle diffusion models were applied to fit the kinetic data, and the results showed that the sorption process followed the pseudo‐second‐order model. Equilibrium data conformed to Langmuir and Redlich–Peterson isotherm models, with a maximum monolayer biosorption capacity of 53.8 mg g^?1 for the Langmuir isotherm at 18 °C. The value of ΔG was estimated to be ? 29.24 kJ mol^?1, indicating the spontaneous nature of the biosorption. The biosorption process was strongly pH‐dependent and favourable at alkaline pH. CONCLUSION: Softstem bulrush, which is readily available and inexpensive, could be employed as a promising biosorbent for the removal of dye. Copyright © 2008 Society of Chemical Industry     

Modification and characterization of poly (ethylene terephthalate)‐grafted‐acrylic acid/acryl amide fiber for removal of lead from human plasma and environmental samples

A new fibrous adsorbent was prepared by grafting acrylic acid/acryl amide (AA/AAm) comonomers onto poly (ethylene terephthalate) (PET) fibers. The resulting sorbent has been characterized by Fourier transform infrared (FT‐IR), elemental analysis, thermogravimetric analysis (TGA), FT‐Raman, and scanning electron microscopy (SEM) and studied for the preconcentration and determination of trace Pb (II) ion from human biological fluid and environmental water samples. The optimum pH value for sorption of the metal ion was 8. The sorption capacity of functionalized resin is 44.1 mg g^?1. The chelating sorbent can be reused for 20 cycles of sorption–desorption without any significant change in sorption capacity. A recovery of 100.2% was obtained for the metal ion with 0.5M nitric acid as eluting agent. Effect of grafting yield, shaking time, shape of sorbent, and pH of the medium on adsorption of the metal ion were investigated. Scatchard analysis revealed that the homogeneous binding sites were formed in the polymers. The equilibrium adsorption data of Pb (II) on modified fiber were analyzed by Langmuir, Freundlich, Temkin, and Redlich‐Peterson models. Based on equilibrium adsorption data, the Langmuir, Freundlich, and Temkin constants were determined as 0.236, 10.544, and 9.497 at pH 8 and 20°C, respectively. The method was applied for lead ions determination from human plasma and sea water sample. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis,characterization, and application of amberlite XAD‐2‐ salicylic acid‐ iminodiacetic acid for lead removal from human plasma and environmental samples

A new chelating resin is prepared by coup‐ling Amberlite XAD‐2 with salicylic acid (SAL) through an azo spacer. Then the polymer support was coupled with iminodiacetic acid (IDA). The resulting sorbent has been characterized by FT‐IR, elemental analysis, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) and studied for the preconcentration and determination of trace Pb (II) ion from human biological fluid and environmental water samples. The optimum pH value for sorption of the metal ion was 5. The sorption capacity of functionalized resin is 67 mg g⁻¹. The chelating sorbent can be reused for 20 cycles of sorption–desorption without any significant change in sorption capacity. A recovery of 95% was obtained for the metal ion with 0.5M nitric acid as eluting agent. The profile of lead uptake on this sorbent reflects good accessibility of the chelating sites in the Amberlite XAD‐2‐SAL/IDA. Scatchard analysis revealed that the homogeneous binding sites were formed in the polymers. The equilibrium adsorption data of Pb (II) on modified resin were analyzed by Langmuir, Freundlich, Temkin, and Redlich‐Peterson models. Based on equili‐brium adsorption data the Langmuir, Freundlich, and Temkin constants were determined 0.428, 20.99, and 7 × 10⁻¹² at pH 5 and 20°C. The method was successfully applied for determination of lead ions in human plasma and sea water sample. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Poly(methacrylic acid)‐modified chitosan for enhancement adsorption of water‐soluble cationic dyes

The preparation of poly(methacrylic acid)‐modified chitosan microspheres and its application for the removal of cationic dyes, methylene blue (MB) and malachite green (MG), in aqueous solution in a batch system were described. The modified chitosan was characterized using SEM, FTIR, and XPS analyses. The effects of the pH of the solution, contact time, and initial dye concentration were studied. The adsorption capacities of the microspheres for the two cationic dyes increased significantly after the modification because a large number of carboxyl groups were introduced. The equilibrium process was better described by the Langmuir than the Freundlich isotherm. According to the Langmuir equation, the maximum adsorption capacities were 1000.0 and 523.6 mg g^?1 for MB and MG, respectively. Kinetic studies showed better correlation coefficients for a pseudo‐second‐order kinetic model, confirming that the sorption rate was controlled by a chemisorption process. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers     

Iminodiacetic acid‐containing polymer brushes grafted onto silica gel for preconcentration and determination of copper(II) in environmental samples

Silica gel has been modified by silylation with 3‐mercaptopropyltrimethoxysilane followed by graft polymerization of dimethylacrylamide and (N,N‐bis‐carboxymethyl)amino‐3‐allylglycerol‐co‐dimethylacrylamide, synthesized via the reaction of allyl glycidyl ether with iminodiacetic acid. The sorbent, poly(AGE/IDA‐co‐DMAA)‐grafted silica gel, has been characterized by FTIR, elemental analysis, thermogravimetric analysis (TGA), FT‐Raman, and scanning electron microscopy and studied for the preconcentration and determination of trace amounts of Cu(II) ion in environmental water samples. The optimum pH value for quantitative sorption of Cu(II) in batch mode was 5.5 and desorption was achieved, using 0.5 mol L^?1 nitric acid. The sorption capacity of functionalized sorbent is 32.3 mg g^?1. The chelating sorbent was reused for 15 sorption–desorption cycles without any significant change in sorption capacity. The profile of copper uptake by the sorbent reflected good accessibility of the chelating sites in the poly(AGE/IDA‐co‐DMAA)‐grafted silica gel. Scatchard analysis demonstrated homogeneous nature of binding sites. The equilibrium adsorption data of Cu(II) on modified sorbent were analyzed by Langmuir, Freundlich, Temkin, and Redlich–Peterson models. Based on equilibrium adsorption data, the Langmuir, Freundlich, and Temkin constants were determined as 0.0665, 4.26, and 8.34, respectively, at pH 5.5 and 20°C. Adsorption isotherms were analyzed at different temperatures to obtain free energy, enthalpy, and entropy of adsorption. The method was applied for Cu(II) determination in sea water samples. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Adsorption characteristics of tannic acid onto the novel protonated palygorskite/chitosan resin microspheres

Novel protonated palygorskite/chitosan resin microspheres (p‐PCRM) were prepared and applied as adsorbents for the removal of tannic acid (TA) from aqueous solution. The effects of palygorskite (PAL) content, the initial pH value of the TA solution, and contact time and temperature on adsorption capacity of the microspheres were investigated. The adsorption process was found to be pH dependant with an optimum activity at pH 8.0. In comparison with protonated chitosan microspheres (224 mg g^?1), the p‐PCRM with 20 wt % PAL content exhibited higher adsorption capacity (455 mg g^?1) for TA at the same adsorption conditions. This may be attributed to the hydrogen bonding between adsorbents and adsorbates, and the porous structure formed by the introduction of PAL, which were confirmed by Fourier transform infrared and the pore parameters analysis. The study of adsorption kinetics and isotherms showed that the sorption processes were better fitted by pseudo‐second‐order equation and the Langmuir equation, respectively. Furthermore, the desorption study implied that the p‐PCRM were recyclable when 0.1M HCl was used as eluents. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Kinetic analysis of the sorption of copper(II) ions on chitosan

The removal of copper ions from aqueous effluents by chitosan was studied in equilibrium and agitated batch contacting systems. The sorption capacities of chitosan for copper ions are 1.26 and 1.12 mmol g^?1 at pH 3.5 and 4.5, respectively. The equilibrium experimental data were best correlated by the Langmuir equation. The kinetics of sorption were studied at an initial solution pH of 4.5 and a chitosan particle size of 355–500 µm. The kinetics were analyzed using four models: the pseudo‐first‐order, pseudo‐second‐order, modified second‐order and Elovich equations. The rate parameters for the four models were determined and the Elovich equation provided the best correlation of the experimental kinetic data. Copyright © 2003 Society of Chemical Industry     

Assessment of kinetic and isotherm models for competitive sorption of Cs+ and Sr2+ from binary metal solution onto nanosized zeolite

This study examined the sorption performance of synthesized nanosized zeolite for the elimination of Cs⁺ and Sr²⁺ cations in a binary metal system. The influence of pH, sorbent amount, temperature, and contact time was studied. The relationship between each of these parameters and the removal efficiency was investigated. An analysis of the rate data was performed using both pseudo-first- and second-order reaction models. The ranking of three equilibrium sorption isotherm models used (Redlich–Peterson, Langmuir, and Freundlich) with a variety of numbers of parameters was determined using the corrected Akaike’s information criterion. The results demonstrate that a pseudo-second-order model fits the sorption kinetic data better than a pseudo-first-order model. The isotherm model rank order that best described the data statistically was Redlich–Peterson?>?Langmuir?>?Freundlich for the cesium ions and Langmuir?>?Redlich–Peterson?>?Freundlich for the strontium ions. Our results revealed that the existence of Sr²⁺ caused a significant reduction of Cs⁺ sorption in the binary metal mixture according to a lumped parameter model and vice versa. The results show that the synthesized material’s surface had a relatively stronger affinity for Cs⁺ than for Sr^2+.     

Equilibrium and Kinetic Studies for Fluoride Adsorption from Water on Zirconium Impregnated Coconut Shell Carbon

Abstract

The batch adsorptive fluoride removal from water by Zirconium ion impregnated coconut shell carbon (ZICSC) was investigated. ZICSC was found to have fluoride adsorption capacity, 25 to 30 times that of plain activated carbon. The effect of various parameters such as pH, agitation time, and adsorbent dosage on fluoride removal were studied. The fluoride adsorption by ZICSC was above 90% for the entire pH range of 2–9 and the adsorption rate was extremely rapid, with 91% of the adsorption being achieved within 10 min of ZICSC contact for an initial fluoride concentration of 10 mg/L. The experimental data have been analyzed by Langmuir, Freundlich, Redlich‐Peterson, and Temkin sorption isotherm models and the adsorption data for fluoride onto ZICSC were better correlated to the Langmuir isotherm. The batch adsorption kinetics have been tested by first order, pseudo‐first order, and pseudo‐second order kinetic models with the subsequent determination of the rate constants of adsorption. The comparison of ZICSC with other adsorbents suggests that ZICSC provides a cost‐effective working solution to the defluoridation problem in the developing countries by its great potential application in fluoride removal from water.     

Comparative adsorption isotherms and modeling of nickel and cobalt citrate complexes onto chelating resins

The sorption characteristics of nickel and cobalt-organic acid complexes on two commercial chelating resins (Purolite S930 and S950) were compared. Purolite S390 is based on an iminodiacetic funtional group and S950 is an aminophosphonic acid resin. Batch equilibrium adsorption tests of these resins were examined and compared using various metal citrate concentrations (15–2000 mg/L) and solution pH. The solution pH of complex solutions was varied by preparing metal solutions in 0.01, 0.1, 0.5 and 1.0 M of citric acid. Equilibrium adsorption data were fitted to empirical isotherm models; linear, Langmuir, Freundlich and Redlich–Peterson (R–P) equations to establish the mechanism for the uptake of the metal complexes onto the resins. Our study showed that nickel-citrate complex adsorption exhibited both monolayer and multilayer adsorption; the mechanism on both resins varying with acid concentration, whereas cobalt complex adsorption was independent of acid concentration but the mechanism of metal loading was found to be influenced by the nature of the resins.     

Fluoride Removal from Aqueous Solutions by Magnesium,Nickel, and Cobalt Calcined Hydrotalcite‐like Compounds

Abstract

Magnesium, nickel and cobalt hydrotalcite‐like compounds (MgHT, NiHT, and CoHT), with similar M²⁺:Al³⁺ ratios were synthesized and characterized by XRD. It was confirmed from XRD that the materials have hydrotalcite‐like structure. MgHT, NiHT, and CoHT were calcined and treated with fluoride solutions in a batch system. F^? ions were determined in the remaining solutions using a fluoride ion selective electrode. The kinetics of the fluoride ions sorption on calcined hydrotalcite‐like compounds (CHT) was best described by the pseudo‐second order model and the equilibrium was reached in less than 300 minutes in all cases (MgCHT, NiCHT, and CoCHT). The sorption isotherms of the fluoride by hydrotalcite like compounds can be explained by the Langmuir‐Freundlich model and, the highest fluoride sorption capacity was obtained for NiCHT (1.202 mgF/gCHT). The fluoride removal from aqueous solutions by calcined hydrotalcite‐like compounds depends on the adsorption properties of the thermal decomposition products and the regeneration reaction mechanism of the hydrotalcite‐like compounds.     

Retention,Thermodynamics and Adsorption Profile of Th(IV) Ions onto 1‐(2‐Pyridylazo)‐2‐Naphthol (PAN) Loaded Polyurethane Foam from Acetate Media and its Separation from Rare Earths

Abstract

The sorption behavior of 2.7×10^?5 M solution of Th(IV) ions on 1‐(2‐pyridylazo)‐2‐naphthol (PAN) loaded polyurethane foam (PUF) has been investigated. The quantitative sorption was occurred from pH 6 to 9 from acetate buffer solutions. The sorption conditions were optimized with respect to pH, shaking time, and weight of sorbent. The sorption data followed the Freundlich, Langmuir, and Dubinin‐Radushkevich (D‐R) isotherms very successfully at low metal ions concentration. The Freundlich isotherm constant (1/n) is estimated to be 0.22±0.01, and reflects the surface heterogeneity of the sorbent. The Langmuir isotherm gives the maximum monolayer coverage is to be 8.61×10^?6 mol g^?1. The sorption free energy of the D‐R isotherm was 17.85±0.33 kJ mol^?1, suggesting chemisorption involving chemical bonding was responsible for the adsorption process. The numerical values of thermodynamic parameters such as enthalpy (ΔH), entropy (ΔS), and Gibbs free energy (ΔG) indicate that sorption is endothermic, entropy driven, and spontaneous in nature. The adsorption free energy (ΔG_ads) and effective free energy (ΔG_eff) are also evaluated and discussed. The effect of different anions on the sorption of Th(IV) ions onto PAN loaded PUF was studied. The possible sorption mechanism on the basis of experimental finding was discussed. A new separation procedure of Th(IV) from synthetic rare earth mixture using batch, column chromatography, and squeezing techniques were reported.     

Highly Efficient Adsorption of Anionic Dyes from Aqueous Solutions Using Sawdust Modified by Cationic Surfactant of Cetyltrimethylammonium Bromide

In the present study, the adsorption behavior of Congo Red (CR) dye from aqueous systems onto sawdust modified by cetyltrimethylammonium bromide, CH₃(CH₂)₁₅N(CH₃)₃Br (CTAB) was attempted. Adsorption experiments were carried out using both batch and column modes under various operating conditions. The effects of some important parameters such as solution pH, adsorbent dosage, initial dye concentration and contact time were investigated. Treatment of the equilibrium data obtained in batch experiments was carried out using Langmuir and Freundlich isotherm equations. Based on the isotherm analysis, it was found that the adsorption of CR dye onto SD fits well to the Langmuir model and the adsorption pattern on CTAB modified sawdust (CTAB/SD) followed the Freundlich isotherm which is indicative of heterogeneity of the adsorption sites on the surfactant-modified sawdust. The maximum adsorption capacity of SD and CTAB/SD were found to be 5.2 and 9.1?mg?g^?1, respectively, according to the Langmuir model. However, much higher differences in sorption capacities were observed for CTAB/SD and SD in the column system (66.73?mg?g^?1). In order to find out the possibility of the exhausted column for frequent use, a regeneration study was also carried out. It was found that the dye uploaded column can be easily regenerated with a high performance using ethanol as the washing solution.     

A modified cellulose adsorbent for the removal of nickel(II) from aqueous solutions

A series of adsorption studies was carried out on a glycidyl methacrylate‐ modified cellulose material functionalised with imidazole (Cellulose‐g‐GMA‐Imidazole) to assess its capacity in the removal of Ni(II) ions from aqueous solution. The study sought to establish the effect of a number of parameters on the removal of Ni(II) from solution by the Cellulose‐g‐GMA‐Imidazole. In particular, the influence of initial metal concentration, contact time, solution temperature and pH were assessed. The studies indicated a Ni(II) uptake on the Cellulose‐g‐GMA‐Imidazole sorbent of approximately 48 mg g^?1 of nickel from aqueous solution. The adsorption process fitted the Langmuir model of adsorption and the binding process was mildly endothermic. The kinetics of the adsorption process indicated that nickel uptake occurred within 400 min and that pseudo‐second order kinetics best describe the overall adsorption process. Nickel(II) adsorption, recovery and re‐adsorption studies indicated that at highly acidic pH values the adsorbent material becomes unstable, but in the range pH 3–6, the adsorbent is stable and shows limited but significant Ni(II) recovery and re‐adsorption capability. Copyright © 2006 Society of Chemical Industry     

Kinetics,Thermodynamics, and Isothermic Evaluation in Sorption Study of Hazardous Dye Using Sodium Dodecylsulfate Physically Impregnated in Polyester‐Type Polyurethane Foam

Use of polyester‐type polyurethane foam (PUF) is an effective adsorbent for the removal of hazardous dye: crystal violet (CV) from an aqueous solution. In this adsorption study, the formation of hydrophobic ion pair (opposite charge attraction) between the charged species, i.e., cationic (basic) dye CV and anionic surfactant sodium dodecylsulfate (SDS) sorbed onto PUF. Chemical calculations were performed using quantum simulation to understand ion‐pair formation for CV–SDS at the semiempirical PM6 level. Adsorption studies were performed using 200 mg cylindrical PUF with an overhead stirrer in solutions containing varying compositions of the dye–surfactant mixture. The equilibrium thermodynamics and kinetics of the adsorption process were studies by measuring CV dye removal as a function of time and temperature. Results show that the formation of the dye–surfactant ion pair is necessary for effective adsorption onto PUF. Various adsorption isotherms, viz., Langmuir, Freundlich, Temkin, Dubinin–Radushkevich (DRK), Harkin‐Jura, and several kinetic models, viz., pseudo‐first order, pseudo‐second order, Elovich, and Intraparticle diffusion were used to fit the spectrophotometric result. The equilibrium adsorption data fit to the Langmuir isotherm gives the maximum adsorption of PUF as 33.39 mg g^?1 from 200 mL 5.0 × 10^?5 mol L^?1 CV solution at 298.15 K. The kinetics study showed that the overall adsorption process follows pseudo‐second‐order kinetics. The Morris–Weber model suggests that an intraparticle diffusion process is active in controlling the adsorption rate. The Freundlich, Temkin, DRK adsorption isotherms showed that solute dye transfers from solution to the PUF adsorbent surface through physical adsorption. The Langmuir and Harkin‐Jura adsorption isotherms suggest that the adsorbent surface is homogeneous in nature. The thermodynamic data showed that the adsorption process is spontaneous and endothermic with a positive enthalpy change and a negative change in Gibb's energy.     

Adsorption of anionic textile dye Acid Green 9 from aqueous solution onto weak or strong base anion exchangers

The aim of this work is to study the thermodynamic and kinetic studies with regard to the adsorption of Acid Green 9 (AG9) on the most efficient resin, namely, acrylic weak base anion exchange resin with ethylenediamine‐functional groups (A1) selected from several anion exchange resins. The influence of the various experimental parameters such as, pH, initial dye concentration, contact time, temperature, and adsorbent dose was investigated by batch experiments. The extent of the dye adsorption increased with the decrease of the initial dye concentration and the increase of the contact time, temperature, and amount of the adsorbent. Adsorption process was quantitative and very fast at low concentrations of the dye. To investigate the mechanism of the adsorption and potential rate‐controlling steps, pseudo first‐ and second‐order, as well as intraparticle diffusion kinetic equations have been used. The adsorption kinetic of AG9 dye from aqueous solution onto A1 could be described by the pseudo second‐order reaction model. The obtained results are in agreement with the Langmuir and Freundlich models. In the optimum conditions established, an adsorption capacity of 500 mg textile dye (72% purity) g^?1 adsorbent (at 293 K) was reached. Desorption experiments by batch and dynamic methods were performed using a solution of 0.05 mol L^?1 NaOH. A series of 13 adsorption–desorption cycles were carried out by the dynamic method with a quantitative adsorption and the desorption efficiency higher than 95%. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Human serum albumin adsorption on poly[(glycidyl methacrylate)‐co‐(methyl methacrylate)] beads modified with a spacer‐arm‐attached L‐histidine ligand

Poly(GMA/MMA) beads were synthesized from glycidyl methacrylate (GMA) and methyl methacrylate (MMA) in the presence of a cross‐linker (i.e. ethyleneglycol dimethacrylate) (EGDMA) via suspension polymerization. The epoxy groups of the poly(GMA/MMA) beads were converted into amino groups with either ammonia or 1,6‐diaminohexane (i.e. spacer‐arm). An L ‐histidine ligand was then covalently immobilized on the aminated (poly(GMA/MMA)‐AH) and/or the spacer‐arm attached (poly(GMA/MMA)‐SAH) beads using glutaric dialdehyde as a coupling agent. Both affinity adsorbents were used in human serum albumin (HSA) adsorption/desorption studies under defined pH, ionic strength or temperature conditions in a batch reactor. The spacer‐arm attached affinity adsorbent resulted in an increase in the adsorption capacity to HSA when compared to the aminated counterpart (i.e. poly(GMA/MMA)‐AH). The maximum adsorption capacities of the affinity adsorbents were found to be significantly high, i.e. 43.7 and 80.2 mg g^?1 (of the beads), while the affinity constants, evaluated by the Langmuir model, were 3.96 × 10^?7 and 9.53 × 10^?7 mol L^?1 for poly(GMA/MMA)‐AH and poly(GMA/MMA)‐SAH, respectively. The adsorption capacities of the affinity adsorbents were decreased for HSA by increasing the ionic strength, adjusted with NaCl. The adsorption kinetics of HSA were analysed by using pseudo‐first and pseudo‐second‐order equations. The second‐order equation fitted well with the experimental data. Copyright © 2005 Society of Chemical Industry     

Enhanced swelling and methylene blue adsorption of polyacrylamide‐based superabsorbents using alginate modified montmorillonite

Polyacrylamide/sodium alginate modified montmorillonite (PAM/SA‐MMT) superabsorbent composites were synthesized by free‐radical polymerization under normal atmospheric conditions. They were characterized by X‐ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy (FTIR). Their water absorbency and methylene blue (MB) adsorption behaviors were studied. Compared with PAM/MMT composites, PAM/SA‐MMT composites demonstrated greater water absorbency (863 g g^?1 in distilled water and 101 g g^?1 in 0.9 wt % NaCl solution) and higher adsorption capacity of 2639 mg g^?1 for MB. The adsorption behaviors of the composites showed that the isotherms and adsorption kinetics were in good agreement with the Langmuir equation and pseudo‐second‐order equation, respectively. FTIR analysis suggested that the MB adsorption of PAM/SA‐MMT composites via a mechanism combined electrostatic, H‐bonding and hydrophobic interaction. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 40013.     

Removal of Copper (II) and Nickel (II) Ions from Aqueous Solutions by a Composite Chitosan Biosorbent

Abstract

A composite chitosan biosorbent (CCB) was prepared by coating chitosan on to ceramic alumina. The adsorption characteristics of the sorbent for copper and nickel ions were studied under batch equilibrium and dynamic flow conditions at pH 4.0. The equilibrium adsorption data were correlated with Langmuir, Freundlich, and Redlich‐Peterson models. The ultimate monolayer capacities, obtained from Langmuir isotherm, were 86.2 and 78.1 mg/g of chitosan for Cu(II) and Ni(II), respectively. In addition, dynamic column adsorption studies were conducted to obtain breakthrough curves. After the column was saturated with metal ions, it was regenerated with 0.1 M sodium hydroxide. The regenerated column was used for a second adsorption cycle.     

Extraction and Adsorption Behavior of Co(II) on HTTA-Impregnated Polyurethane Foam

Abstract

The batch extraction of Co(II) from aqueous solutions with open cell polyethertype HTTA-loaded polyurethane (PU) foam has been studied using a radiotracer technique. The effect of pH, shaking time, and loading capacity has been investigated. The membrane properties of loaded PU foam sorbent offer unique advantage of adsorption. The fundamental studies of adsorption show that the classical Freundlich and Langmuir isotherms are followed in the entire concentration range of a 10^?5 to 10^?2 M solution of cobalt. The sorption mean free energy from the Dubinin-Radushkevich isotherm is found to be 13.8 kJ·mol^?1 and the loading capacity 4.44 mg·g^?1, suggesting that the ion-exchange or chemisorption mechanism operates. The kinetic parameters of adsorption also support a chemisorption mechanism and the first-order rate law. The rate constants and activation energies of sorption and desorption have been evaluated. The thermodynamic function of adsorption of ΔH, ΔS, ΔG, and equilibrium constant K _c have been calculated. The process of adsorption is established to be endothermic and chemisorption, stabilized through thermodynamic functions.