A chelating cellulose adsorbent for the removal of Cu(II) from aqueous solutions

Regenerated cellulose wood pulp was grafted with the vinyl monomer glycidyl methacrylate (GMA) using ceric ammonium nitrate as initiator and was further fuctionalised with imidazole to produce a novel adsorbent material, cellulose‐g‐GMA‐imidazole. All cellulose, grafted cellulose and functionalized cellulose grafts were physically and chemically characterized using a number of analytical techniques, including elemental analysis, Fourier transform infrared spectroscopy, thermogravimetric analysis, differential thermal analysis, and scanning electron microscopy. The cellulose‐g‐GMA material was found to contain 1.75 mmol g^?1 epoxy groups. These epoxy groups permitted introduction of metal binding functionality to produce the cellulose‐g‐GMA‐imidazole final product. Following characterization, a series of adsorption studies were carried out on the cellulose‐g‐GMA‐imidazole to assess its capacity in the removal of Cu²⁺ ions from solution. Cellulose‐g‐GMA‐imidazole sorbent showed an uptake of ～70 mg g^?1 of copper from aqueous solution. The adsorption process is best described by the Langmuir model of adsorption, and the thermodynamics of the process suggest that the binding process is mildly exothermic. The kinetics of the adsorption process indicated that copper uptake occurred within 30 min and that pseudo‐second‐order kinetics best describe the overall process. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 2006     

Optimization and analysis of nickel adsorption on microwave irradiated rice husk using response surface methodology (RSM)

BACKGROUND: The removal of heavy metals using adsorption techniques with low cost biosorbents is being extensively investigated. The improved adsorption is essentially due to the pores present in the adsorbent. One way of improving the porosity of the material is by irradiation of the precursor using microwaves. In the present study, the adsorption characteristics of nickel onto microwave‐irradiated rice husks were studied and the process variables were optimized through response surface methodology (RSM). RESULT: The adsorption of nickel onto microwave‐irradiated rice husk (MIRH) was found to be better than that of the raw rice husk (RRH). The kinetics of the adsorption of Ni(II) from aqueous solution onto MIRH was found to follow a pseudo‐second‐order model. Thermodynamic parameters such as standard Gibbs free energy (ΔG°), standard enthalpy (ΔH°), and standard entropy (ΔS°) were also evaluated. The thermodynamics of Ni(II) adsorption onto MIRH indicates that it is spontaneous and endothermic in nature. The response surface methodology (RSM) was employed to optimize the design parameters for the present process. CONCLUSION: Microwave‐irradiated rice husk was found to be a suitable adsorbent for the removal of nickel(II) ions from aqueous solutions. The adsorption capacity of the rice husk was found to be 1.17 mg g^?1. The optimized parameters for the current process were found as follows: adsorbent loading 2.8 g (100 mL)^?1; Initial adsorbate concentration 6 mg L^?1; adsorption time 210 min.; and adsorption temperature 35 °C. Copyright © 2008 Society of Chemical Industry     

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     

Efficient removal of Cu(II) using amino‐functionalized superparamagnetic nanoparticles prepared via SI‐ATRP

An amino‐functionalized nano‐adsorbent (DETA‐MNPs) was prepared by a process involving: (1) synthesis of superparamagnetic Fe₃O₄ nanoparticles; (2) introduction of amino groups after which ATRP initiator was anchored; (3) grafting of glycidyl methacrylate (GMA) via SI‐ATRP; and (4) ring‐opening reaction of epoxy groups with diethylenetriamine (DETA). The nano‐adsorbent was characterized by Fourier transform infrared spectroscopy (FT‐IR), X‐ray diffraction (XRD), transmission electron microscope (TEM), and vibrating sample magnetometer (VSM) and applied to remove Cu(II) in batch experiments. The effects of pH, Cu(II) concentrations, solution ionic strength, and contact time were investigated. The results show that the DETA‐MNPs are spherical with cubic spine structure, high saturation magnetization (41.9 emu g^?1), and an average diameter of 10 nm. The maximum Cu(II) adsorption capacity achieves 83.33 mg g^?1 at pH 5.0 by Langmuir model. The adsorption process is highly pH‐dependent and reaches equilibrium within 20 min. Furthermore, the DETA‐MNPs exhibit excellent dispersibility and reusability. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 132, 42859.     

Walnut shell supported nanoscale Fe0 for the removal of Cu(II) and Ni(II) ions from water

The walnut shell supported nanoscale zero‐valent iron (walnut‐nZVI) was prepared from sodium borohydride, iron(II) chloride tetrahydrate, and walnut shell by liquid phase chemical reduction and characterized by FTIR, TEM, and XRD. The composites were tested as adsorbent for the removal of Cu(II) or Ni(II) ions. The equilibrium data were analyzed by the Langmuir, Freundlich, Dubinin–Radushkevich, which revealed that Langmuir isotherm was more suitable for describing Cu(II) and Ni(II) ions adsorption than the other two isotherm models. The results indicated that the maximum adsorption capacity was higher than some other modified biomass waste adsorbents under the proposed conditions, were 458.7, 327.9 mg g^?1 for Cu(II) or Ni(II). The adsorption kinetics data indicated that the adsorption fitted well with the pseudo‐second‐order kinetic model. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43304.     

The use of exhausted olive cake ash (EOCA) as a low cost adsorbent for the removal of toxic metal ions from aqueous solutions

The removal characteristics of cadmium (Cd(II)) and nickel (Ni(II)) ions from aqueous solution by exhausted olive cake ash (EOCA) were investigated under various conditions of contact time, pH, initial metal concentration and temperature. Batch kinetic studies showed that an equilibrium time of 2 h was required for the adsorption of Ni(II) and Cd(II) onto EOCA. Equilibrium adsorption is affected by the initial pH (pH₀) of the solution. The pH₀ 6.0 is found to be the optimum for the individual removal of Cd(II) and Ni(II) ions by EOCA. The adsorption test of applying EOCA into synthetic wastewater revealed that the adsorption data of this material for nickel and cadmium ions were better fitted to the Langmuir isotherm since the correlation coefficients for the Langmuir isotherm were higher than that for the Freundlich isotherm. The estimated maximum capacities of nickel and cadmium ions adsorbed by EOCA were 8.38 and 7.32 mg g⁻¹, respectively. The thermodynamic parameters for the adsorption process data were evaluated using Langmuir isotherm. The free energy change (ΔG°) and the enthalpy change (ΔH°) showed that the process was feasible and endothermic respectively. As the exhausted olive cake is discarded as waste from olive processing, the adsorbent derived from this material is expected to be an economical product for metal ion remediation from water and wastewater.     

Investigation on selective adsorption of Hg(II) ions using 4‐vinyl pyridine grafted poly(ethylene terephthalate) fiber

In the work, poly(ethylene terephthalate) (PET) fibers were grafted with 4‐vinyl pyridine (4‐VP) monomer using benzoyl peroxide (Bz₂O₂) as initiator in aqueous media. The removal of Hg(II) ions from aqueous solution by the reactive fiber was examined by batch equilibration technique. Effects of various parameters such as pH, graft yield, adsorption time, initial ion concentration, and adsorption temperature on the adsorption amount of metal ions onto reactive fibers were investigated. The optimum pH of Hg(II) was found 3. The maximum adsorption capacity was found as 137.18 mg g^?1. Moreover such parameters as the adsorption kinetics, the adsorption isotherm, desorption time and the selectivity of the reactive fiber were studied. The adsorption kinetics is in better agreement with pseudo‐first order kinetics, and the adsorption data are good fit with Freundlich isotherms. The grafted fiber is more selective for Hg(II) ions in the mixed solution of Hg(II)‐Ni(II), Hg(II)‐Zn(II), and Hg(II)‐Ni(II)‐Zn(II) at pH 3. Adsorbed Hg(II) ions were easily desorbed by treating with 1M HNO₃ at room temperature. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

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.     

Batch and fixed‐bed column adsorption of Cu(II), Pb(II) and Cd(II) from aqueous solution onto functionalised SBA‐15 mesoporous silica

Functionalised SBA‐15 mesoporous silica with polyamidoamine groups (PAMAM‐SBA‐15) was successfully prepared with the structure characterised by X‐ray diffraction, nitrogen adsorption–desorption, Fourier transform infrared spectra and thermogravimetric analysis. PAMAM‐SBA‐15 was applied as adsorbent for Cu(II), Pb(II) and Cd(II) ions removal from aqueous solution. The effects of the solution pH, adsorbent dosage and metal ion concentration were studied under the batch mode. The Langmuir model was fitted favourably to the experimental data. The maximum sorptive capacities were determined to be 1.74 mmol g^?1 for Cu(II), 1.16 mmol g^?1 for Pb(II) and 0.97 mmol g^?1 for Cd(II). The overall sorption process was fast and its kinetics was fitted well to a pseudo‐first‐order kinetic model. The mean free energy of sorption, calculated from the Dubinin–Radushkevich isotherm, indicated that the sorption of lead and copper, with E > 16 kJ mol^?1, followed the sorption mechanism by particle diffusion. The adsorbent could be regenerated three times without significant varying its sorption capacity. A series of column tests were performed to determine the breakthrough curves with varying bed heights and flow rates. The breakthrough data gave a good fit to the Thomas model. Maximum sorption capacity of 1.6, 1.3 and 1.0 mmol g^?1 were found for Cu(II), Pb(II) and Cd(II), respectively, at flow rate of 0.4 mL min^?1 and bed height of 8 cm, which corresponds to 83%, 75% and 73% of metallic ion removal, respectively, which very close to the value determined in the batch process. Bed depth service time model could describe the breakthrough data from the column experiments properly. © 2012 Canadian Society for Chemical Engineering     

Nickel and cobalt sorption on anaerobic granular sludges: kinetic and equilibrium studies

The kinetics and equilibria of sorption of the divalent metal ions cobalt and nickel onto anaerobic granular sludge are described. Single component and binary equimolar systems were studied at different pH values (pH 6, 7 and 8). The kinetic modelling of metal sorption by anaerobic granular sludge has been carried out using Lagergren equations. On fitting the experimental kinetic data both in first‐ and pseudo‐second‐order equations, the regression analysis of a pseudo‐second‐order equation gave a higher r² value, indicating that both external mass transfer and intra‐particle diffusion are involved in the sorption process. The experimental isotherm data were analysed using the Langmuir, Freundlich and Redlich–Peterson equations. The Redlich isotherm, a combination of the Langmuir and Freundlich equations, was found to have the highest regression correlation coefficients at pH 7. At pH 8, the Langmuir mechanism dominated for cobalt and nickel adsorption. In contrast, at pH 6, the Freundlich equation gave a better correlation coefficient which suggests a more heterogeneous adsorption at that pH. The maximal adsorption capacity of the granular sludge, as determined by the Langmuir equation, for cobalt or nickel in single systems (8.92 mg g^?1 Co TSS; 9.41 mg g^?1 Ni TSS, pH 7) compared with binary systems (8.06 mg g^?1 Co TSS; 8.43 mg g^?1 Ni TSS, pH 7) showed no great difference in the accumulation of these metals onto granular sludge. Copyright © 2004 Society of Chemical Industry     

Effect of nickel coating on carbon for adsorption of cadmium from aqueous solutions

Nickel was coated on carbon and it was characterized by SEM and XRD. Sorption of Cd(II) ions onto carbon and nickel‐coated carbon (Ni/C), effect of acids, pH, shaking time, loading capacity, and adsorbent weight has been investigated. Acids reduce sorption and maximum sorption takes place from deionized water and R_d values for carbon and Ni/C in deionized water are 212.9 ± 0.9 and 232.5 ± 2.5. The sorption data followed the Freundlich, Dubinin–Radushkevich (D–R), isotherms and different parameters have been calculated. Sorption free energy values have been calculated and are 12.56 ± 0.19 and 14.84 ± 0.196 for carbon and Ni/C and indicate that adsorption process is chemisorption. Increase in adsorption shows the increase in catalytic activity of the adsorbent. The variation of sorption with temperature has been used to calculate the values of ΔH, ΔS, and ΔG for Cd(II) sorption. These values show that adsorption of Cd(II) ions on the adsorbents is endothermic, spontaneous, and entropy driven. Coating of carbon with nickel has improved its adsorption properties. Adsorption behaviour provides useful information for the catalytic activity of catalysts.     

Poly(ethyleneimine) functionalized organic-inorganic hybrid silica by hydrothermalassisted surface grafting method for removal of nickel(II)

Poly(ethyleneimine)-functionalized organic-inorganic hybrid silica adsorbent was synthesized by hydrothermal-assisted surface grafting technique for the removal of Ni(II) ions from aqueous solution, and was characterized by FT-IR, nitrogen adsorption and the static adsorption-desorption experiment method. The results indicated that the maximum static adsorption capacity of Ni(II) on poly(ethyleneimine)-functionalized hybrid silica adsorbent by hydrothermal heating method was 1.6 times as much as the conventional heating method. The poly(ethyleneimine)-functionalized hybrid silica adsorbent offered a fast kinetics for the adsorption of Ni(II), had a substantial binding capacity in the range of pH 4-8 and could be used repeatedly. The Langmuir adsorption model was more favorable than the Freundlich and Dubinin-Radushkevich adsorption models. The adsorption followed a pseudo-second-order model compared with pseudo-first-order model. Various thermodynamic parameters such as ΔG°, ΔH° and ΔS° indicated that the adsorption process was spontaneous and endothermic. The results showed that poly(ethyleneimine)-functionalized hybrid silica adsorbent could be employed as an effective material for the removal of Ni(II) ions from aqueous solution.     

Preparation of grafted polytetrafluoroethylene fibers and adsorption of bilirubin

BACKGROUND: A successful hemoperfusion technique requires that the adsorbent for bilirubin should have a high specificity, adsorption capacity and adsorption rate, blood compatibility and no toxicity. Compared with polymer microbeads, polytetrafluoroethylene (PTFE) fibers have many advantages. The aim of the work reported here was to prepare a new polytetrafluoroethylene‐graft‐poly(glycidyl methacrylate)‐block‐polyethyleneimine (PTFE‐g‐PGMA‐b‐PEI) adsorbent for bilirubin based on PTFE fibers by the ⁶⁰Co radiation‐induced graft polymerization of GMA followed by the chemical modification of the epoxy groups on the PTFE‐g‐PGMA fibers with PEI. In addition, the adsorption properties of this novel adsorbent for bilirubin were examined. RESULTS: The highest content of amino groups obtained on the PTFE‐g‐PGMA‐b‐PEI fibers was 1.87 mmol g^?1. The maximum adsorption capacity of the grafted fibers was 9.6 mg g^?1 at pH = 6.5. Bilirubin adsorption on these fibers obeyed the Langmuir model. Also, these fibers possessed the ability to selectively adsorb bilirubin in the presence of bovine serum albumin. CONCLUSION: The PTFE‐g‐PGMA‐b‐PEI fibers have a high adsorption capacity for bilirubin and excellent adsorption properties. In addition, this new adsorbent is inexpensive, easy to prepare and has no toxicity. So the PTFE‐g‐PGMA‐b‐PEI fibers as a biomedical adsorbent are promising for the removal of bilirubin through the hemoperfusion technique. Copyright © 2009 Society of Chemical Industry     

Biosorption of Pb(II) and Ni(II) ions by chemically modified Eclipta alba stem powder: Kinetics and equilibrium studies

Biosorption of Pb(II) and Ni(II) ions onto the Eclipta alba stem powder (EAS) was investigated in a batch system. The biosorbent was characterized by fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), transmission electron microscopy (TEM) and elemental analysis. Adsorption influencing factors like pH, adsorbent dose, initial metal ion concentration and contact time were investigated. The adsorption mechanism of Pb(II) and Ni(II) followed the pseudo-second-order kinetic model (R² > 0.998). The Langmuir isotherm model fitted well and the maximum monolayer adsorption capacity of the sorbent for Pb(II) and Ni(II) was found to be 66.2 ± 1.9 mg g^?1and 62.5 ± 1.8 mg g^?1, respectively. Desorption and recovery were carried out using dilute HCl solution.     

Synthesis and characterization of sulphanilic acid–dithiooxamide–formaldehyde terpolymer resin for adsorption of nickel ions from waste water

A new chelating terpolymer resin of sulphanilic acid–dithiooxamide–formaldehyde (SDTOF) was synthesized. Dithiooxamide–formaldehyde (DTOF) was prepared by the reaction of dithiooxamide and formaldehyde. These resins were characterized using Fourier transform infrared spectroscopy, proton nuclear magnetic resonance, and scanning electron microscopy. Chelating resins beads were applied for adsorption of nickel (II) ions by batch and column techniques. Sorption experiments were performed by varying pH, agitation time, sorbent dosage and initial concentration of nickel (II) ion solution. SDTOF and DTOF resins showed adsorption capacity of 188.3 and 99.8 mg g^?1, respectively. Nickel adsorption isotherms data were fitted to Langmuir isotherm. Kinetic studies showed the adsorption process followed pseudosecond‐order rate model. Desorption of Ni(II) ions was done using 0.1 M HCl, HNO₃, and ethylenediamine tetraacetic acid solutions. The reusability of SDTOF and DTOF resins for the removal of Ni(II) ions was also determined after 10 sorption?desorption cycles. POLYM. ENG. SCI., 55:163–172, 2015. © 2014 Society of Plastics Engineers     

Hierarchically porous graphitic carbon monoliths containing nickel nanoparticles as magnetically separable adsorbents for dyes

The hierarchically porous graphitic carbon monoliths containing nickel nanoparticles (HPGCM‐Ni) were fabricated via multi‐component co‐assembly in polyurethane (PU) foam scaffold associated with a direct carbonization process from triblock copolymer F127, diblock copolymer PDMS‐PEO, phenolic resol, and nickel nitrate and subsequent silicates removal with NaOH solution. The decomposable PU foam scaffold played important role in the process of multi‐component co‐assembly and macrostructure formation. The nickel salts were reduced to metallic Ni nanoparticles during the carbonization process. The obtained HPGCM‐Ni materials exhibited macropores of 100–450 μm, mesopore size of 7.2 nm, BET surface area of 725 m² g^?1, pore volume of 0.74 cm³ g^?1, and saturation magnetization of 2.3 emu g^?1. Using methyl orange as model dye pollutant in water, HPGCM‐Ni samples showed good adsorption capacity of 440 mg g^?1, exhibiting excellent adsorption characteristics desirable for the application in adsorption of dyes and separation under an external magnetic field. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41322.     

Polymeric superabsorbing composite prepared using a glow‐discharge electrolysis plasma for the removal of divalent heavy metal ions from aqueous solutions and its swelling properties

A novel polymeric superabsorbing composite was prepared using the graft copolymerization of acrylic acid (AANa, 70% neutralization with NaOH) and 2‐acrylamido‐2‐methyl propane sulfonic acid (AMPS) onto the hydroxyethyl cellulose (HEC) [HEC‐g‐P(AANa‐co‐AMPS)], which was initiated by means of a glow‐discharge electrolysis plasma rather than a chemical initiator. The composite material was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermal gravimetric analysis (TGA). We obtained absorbencies of 2490 g g^?1 for distilled water and of 109 g g^?1 for 0.9 wt% NaCl solution. Results show that the maximum adsorption capacities for Ni(II), Cu(II), Cd(II), Pb(II), and Hg(II) from aqueous solution were 974.84, 975.43, 1535.52, 1970.47, and 1879.53 mg g^?1, respectively. The adsorption isotherm followed the Langmuir isotherm model very well. Adsorption kinetics results indicate that the fast adsorption rate followed the pseudo‐second‐order kinetics equations. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers     

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     

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 isotherms,kinetic, and desorption studies on removal of toxic metal ions from aqueous solutions by polymeric adsorbent

Adsorption of Cd(II), Co(II), and Ni(II) on aminopyridine modified poly(styrene‐alt‐maleic anhydride) crosslinked by 1,2‐diaminoethane as an ion exchange resin has been investigated in aqueous solution. Adsorption behavior of these metal ions on the resin was studied by varying the parameters such as pH (2–6), adsorbent dose (0–4.0 g/L), contact time (0–240 min), and metal ions concentration (20–300 mg/L). Adsorption percentage was increased by increasing each of these parameters. The isotherm models such as: Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich were used to describe adsorption equilibrium. The results showed that the best fit was achieved with the Langmuir isotherm equation, yielding maximum adsorption capacities of 81.30, 49.02, and 76.92 mg/g for Cd(II), Co(II), and Ni(II), respectively. The pseudo‐first‐order, pseudo‐second‐order, and intra‐particle diffusion kinetics equations were used for modeling of adsorption data and it was shown that pseudo‐second‐order kinetic equation could best describe the adsorption kinetics. The intra‐particle diffusion study revealed that external diffusion might be involved in this case. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41642.