Pyromellitic dianhydride‐modified β‐cyclodextrin microspheres for Pb(II) and Cd(II) adsorption

In this work, the pyromellitic dianhydride (PMDA)‐grafted β‐cyclodextrin (β‐CD) microspheres have been prepared for the removal of lead and cadmium metal ions in aqueous solution by a batch‐equilibration technique. The effects of the pH of the solution, contact time, and initial metal concentration were studied. The adsorption capacities for the two metal ions increase significantly as a large number of carboxyl groups are present on the microspheres surface. The equilibrium process is better described by the Langmuir isotherm than the Freundlich isotherm. The maximum adsorption capacities are 135.69 and 92.85 mg g^?1 for Pb(II) and Cd(II), respectively. Kinetic studies show good correlation coefficients for a pseudosecond‐order kinetic model, confirming that the sorption rate is controlled by chemical adsorption. The regeneration of the adsorbent can be carried out by treating the loaded microspheres with 0.2 (mol L^?1) HCl obtaining high desorption rate for the two metal ions. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Removal of lead (II) and cadmium (II) from aqueous solutions using spent Agaricus bisporus

The sorption of Pb and Cd from aqueous solutions by spent Agaricus bisporus was investigated. The effects of contact time, pH, ionic medium, initial metal concentration, other metal ions presence and ligands were studied in batch experiments at 25°C. Maximum sorption for both metals was found to occur at an initial pH of around 5.5. The equilibrium process was well described by the Langmuir isotherm model, with maximum sorption capacities of 0.2345 and 0.1273 mmol g^?1 for Pb and Cd respectively. Kinetic data followed the pseudo‐second‐order kinetic model. The presence of NaCl and NaClO₄ caused a reduction in Cd sorption, while Pb sorption was not remarkably affected. The presence of other metals did not affect Pb removal, while the Cd removal was much reduced. HCl or EDTA solutions were able to desorb Cd from the spent Agaricus bisporus (SAB) completely, while an approximately 60% and 15% desorption yield was obtained for Pb when HCl 0.01 mol L^?1 or EDTA 0.001 mol L^?1 were used, respectively. The results of FTIR, SEM and EDX analysis indicated that other mechanisms, such as surface complexation and electrostatic interactions, must be involved in the metal sorption in addition to ion exchange. © 2012 Canadian Society for Chemical Engineering     

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     

Polymer‐grafted banana (Musa paradisiaca) stalk as an adsorbent for the removal of lead(II) and cadmium(II) ions from aqueous solutions: kinetic and equilibrium studies

This study examined the effectiveness of a new adsorbent prepared from banana (Musa paradisiaca) stalk, one of the abundantly available lignocellulosic agrowastes, in removing Pb(II) and Cd(II) ions from aqueous solutions. The adsorbent (PGBS‐COOH) having a carboxylate functional group at its chain end was synthesized by graft copolymerization of acrylamide on to banana stalk, followed by functionalization. Batch adsorption experiments were carried out as a function of solution pH, ionic strength, contact time, metal concentration, adsorbent dose and temperature. A pH range of 5.5–8.0 was found to be effective for the maximum removal for both Pb(II) and Cd(II). Metal uptake was found to decrease with increase in ionic strength due to the expansion of the diffuse double layer and, more importantly, the formation of some chloro complexes (since NaCl was used in the adjustment of ionic strength), which do not appear to be adsorbed to the same extent as cations [M²⁺ and M(OH)⁺]. The kinetic studies showed that an equilibrium time of 3 h was needed for the adsorption of Pb(II) and Cd(II) on PGBS‐COOH and adsorption processes followed a pseudo‐second‐order equation. The Langmuir isotherm model fitted the experimental equilibrium data well. The maximum sorption capacity for Pb(II) and Cd(II) ions was 185.34 and 65.88 mg g^?1, respectively, at 30 °C. The thermodynamic parameters such as changes in free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) were derived to predict the nature of adsorption. The isosteric heat of adsorption was found to be independent of surface coverage. Adsorption experiments were also conducted using a commercial cation exchanger, Ceralite IRC‐50, for comparison. Synthetic wastewater samples were treated with the adsorbent to demonstrate its efficiency in removing Pb(II) and Cd(II) ions from industrial wastewaters. Acid regeneration was tried for several cycles with a view to recovering the sorbed metal ions and also restoring the sorbent to its original state. Copyright © 2005 Society of Chemical Industry     

Synthesis,characterization, and application of a new chelating resin functionalized with dithiooxamide

Chloromethylated polystyrene‐divinylbenzene has been functionalized with dithiooxamide. The resulting chelating resin (DTOA) has been characterized by elemental analyses, infrared spectroscopy, thermogravimetric analysis, and metal ion sorption capacities. It has been used for the preconcentration and separation of Cu(II), Zn(II), Cd(II), and Pb(II) prior to their determination by FAAS. Parameters such as the amount of the resin, effect of pH, equilibration rate, sorption and desorption of metal ions, and effect of diverse ions have been studied. The maximum sorption capacities found are 0.97, 0.12, 0.08, and 0.12 mmol g^?1 for Cu(II), Zn(II), Cd(II), and Pb(II) at pH 6.0, 5.5, 1.0, and 5.5, respectively. The preconcentration factors are 100, 100, 50, and 50 for Cu(II), Zn(II), Cd(II), and Pb(II), respectively. Recoveries of the metal ions were 96 ± 5, 97 ± 6, 96 ± 5, and 96 ± 5 at 95% confidence level, whereas the limits of detection are 2.0, 1.3, 2.5, and 25.0 μg L^?1 for Cu(II), Zn(II), Cd(II), and Pb(II), respectively. The calibration curves were linear up to 12 μg mL^?1 (R² = 1.000), 2 μg mL^?1 (R² = 0.998), 2 μg ml^?1 (R² = 1.000), and 5 μg mL^?1 (R² = 0.979) for Cu(II), Zn(II), Cd(II), and Pb(II), respectively. The reliability of the method has been tested by analyzing certified samples. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2281–2285, 2007     

Sorption of cadmium and lead ions on modified groundnut (Arachis hypogea) husks

The removal of cadmium and lead ions from aqueous solutions by groundnut husks modified by reaction with EDTA (% N = 12.05) was examined by equilibrium sorption studies at 29°C. The maximum metal ion binding capacity of the EDTA-modified husk determined from the sorption isotherm from solutions of pH 6.8 was found to be 0.36 mmol g^?1 and 0.19 mmol g^?1 for Cd(II) and Pb(II) ions, respectively. It was found that the rate of sorption was particle-diffusion controlled, and the particle-diffusion control rate coefficient was determined to be of the order of 10^?2 min^?1.     

Optimization of kinetic data for two‐stage batch adsorption of Pb(II) ions onto tripolyphosphate‐modified kaolinite clay

BACKGROUND: Most adsorption studies consider only the adsorption of pollutants onto low cost adsorbents without considering how equilibrium and kinetic data can be optimized for the proper design of adsorption systems. This study considers the optimization of kinetic data obtained for the removal of Pb(II) from aqueous solution by a tripolyphosphate modified kaolinite clay adsorbent. RESULTS: Modification of kaolinite clay with pentasodium tripolyphosphate increases its cation adsorption capacity (CEC) and specific surface area (SSA) from 7.81 to 78.9 meq (100 g)^?1 and 10.56 to 13.2 m² g^?1 respectively. X‐ray diffraction patterns for both unmodified and tripolyphosphate‐modified kaolinite clay suggest the modification is effective on the surface of the clay mineral. Kinetic data from the batch adsorption of Pb(II) onto the tripolyphosphate‐modified kaolinite clay adsorbent were optimized to a two‐stage batch adsorption of Pb(II) using the pseudo‐second‐order kinetic model. Mathematical model equations were developed to predict the minimum operating time for the adsorption of Pb(II). Results obtained suggest that increasing temperature and decreasing percentage Pb(II) removal by the adsorbent enhanced operating time of the adsorption process. The use of two‐stage batch adsorption reduces contact time to 6.7 min from 300 min in the single‐stage batch adsorption process for the adsorption of 2.5 m³ of 500 mg L^?1 Pb(II) under the same operating conditions. CONCLUSION: Results show the potential of a tripolyphosphate‐modified kaolinite clay for the adsorption of Pb(II) from aqueous solution and the improved efficiency of a two‐stage batch adsorption process for the adsorption of Pb(II) even at increased temperature. Copyright © 2009 Society of Chemical Industry     

Evaluation of sorption behavior of polymethylene-bis(2-hydroxybenzaldehyde) for Cu(II), Ni(II), Fe(III), Co(II) and Cd(II) ions

Poly[5,5??-methylene-bis(2-hydroxybenzaldehyde)1,2-phenylenediimine] resin was prepared and characterized by employing elemental, thermal analysis, FTIR, and UV?Cvisible spectroscopy. The metal uptake behavior of synthesized polymer towards Cu(II), Co(II), Ni(II), Fe(III) and Cd(II) ions was investigated and optimized with respect to pH, shaking speed, and equilibration time. The sorption data of all these metal ions followed Langmuir, Freundlich, and Dubinin?CRadushkevich isotherms. The Freundlich parameters were computed 1/n?=?0.31?±?0.02, 0.3091?±?0.02, 0.3201?±?0.05, 0.368?±?0.04, and 0.23?±?0.01, A?=?3.4?±?0.03, 4.31?±?0.02, 4.683?±?0.01, 5.43?±?0.03, and 2.8?±?0.05?mmol?g^?1 for Cu(II), Co(II), Ni(II), Fe(III), and Cd(II) ions, respectively. The variation of sorption with temperature gives thermodynamic quantity (??H) in the range of 36.72?C53.21?kJ/mol. Using kinetic equations (Morris?CWeber and Lagergren equations), values of intraparticle transport and the first-order rate constant was computed for all the five metals ions. The sorption procedure is utilized to preconcentrate these ions prior to their determination by atomic absorption spectrometer. It was found that the adsorption capacity values for metal-ion intake followed the following order: Cd(II)?>?Co(II)?>?Fe(III)?>?Ni(II)?>?Cu(II).     

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.     

Polymer‐supported iminodiacetamides for selective mercury extraction

A new polymeric resin with iminodiacetamide functions has been prepared for the selective extraction of mercuric ions. This polystyrene sulfone amide‐based resin with a 9.6 mmol g^?1 amide content is able to selectively sorb mercury over many metal ions, including Cd(II), Zn(II), Fe(III), and Pb(II). Among these, Cd(II) and Zn(II) ions are not sorbed at all, and Fe(III) and Pb(II) ions show only trace absorptions (0.58 and 0.17 mmol/g, respectively) under the same conditions. The selectivity of the resin, its high mercury loading capacity (4.23 mmol g^?1), and its ability to regenerate via acetic acid make it a promising material for the large‐scale selective separation of mercuric ions from aqueous mixtures. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1316–1321, 2003     

Biosorption of Pb(II) and Cd(II) ions from aqueous solution using polyaniline/chitin composite

In this study, chitin (Ch) was made composite with polyaniline (PANI) and used for the removal of Pb(II) and Cd(II) ions from aqueous solution. Characterization techniques such as Fourier transform infrared spectroscopy, scanning electron microscope, energy-dispersive X-ray analyser and X-ray diffraction were employed to characterize the prepared PANI/Ch composite. Influence of various equilibrium parameters on the adsorption of Pb(II) and Cd(II) ions onto PANI/Ch composite was investigated. The adsorption process followed the Freundlich isotherm model, and the calculated maximum monolayer sorption capacity of PANI/Ch composite for Pb(II) and Cd(II) ions is 7.03 and 6.05 mg g^?1 at 303 K. The kinetic data were well described by the pseudo-second-order model.     

Synthesis and characterization of polyacrylamide‐grafted coconut coir pith having carboxylate functional group and adsorption ability for heavy metal ions

The present investigation was undertaken to evaluate the effectiveness of a new adsorbent prepared from coconut coir pith (CP), a coir industry‐based lignocellulosic residue in removing metal ions from aqueous solutions. The adsorbent (PGCP‐COOH) having a carboxylate functional group at the chain end was prepared by grafting polyacrylamide onto CP using potassium peroxydisulphate as an initiator and in the presence of N,N′‐methylenebisacrylamide as a crosslinking agent. The adsorbent was characterized by infrared (IR) spectroscopy, thermogravimetry (TG), X‐ray diffraction (XRD) patterns, scanning electron microscopy (SEM), and potentiometric titration. The adsorbent exhibits very high adsorption potential for the removal of Pb(II), Hg(II), and Cd(II) ions from aqueous solutions. The optimum pH range for metal ion removal was found to be 6.0–8.0. The adsorption process follows a pseudo‐second‐order kinetic model. The adsorption capacities for Hg(II), Pb(II), and Cd(II) calculated using the Langmuir isotherm equation were 254.52, 189.49, and 63.72 mg g^?1, respectively. Adsorption isotherm experiments were also conducted for comparison with a commercial carboxylate form cation exchanger. Different industry wastewater samples were treated by the PGCP‐COOH to demonstrate its efficiency in removing heavy metals from wastewater. The reusability of the PGCP‐COOH was also demonstrated using 0.2M HCl. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3670–3681, 2007     

Macromolecular Chelator‐Amberlite XAD‐16 Anchored with 2,3‐Dihydroxypyridine (DHP) for Enrichment of Metal Ions before their Determination by Flame Atomic Absorption Spectrometry

Abstract

2,3‐Dihydroxypyridine (DHP) was loaded onto Amberlite XAD‐16 via azo linker and the resulting resin AXAD‐16‐DHP explored for enrichment of Zn(II), Mn(II), Ni(II), Pb(II), Cd(II), Cu(II), Fe(III), and Co(II) in the pH range 4.0–6.5. The sorption capacity was found in the range 120–512 µmol g^?1 and the preconcentration factor from 200 to 300. Tolerance limits for foreign species are reported. The kinetics of sorption is fast, as t_1/2 is generally ≤2 min. The chelating resin can be reused for fifty cycles of sorption‐desorption without any significant change (≤2.0%) in its sorption capacity. The limit of detection values (blank + 3s) are 2.90, 3.80, 5.17, 7.02, 1.91, 1.63, 4.59, and 5.02 µg L^?1 for Zn, Mn, Ni, Pb, Cd, Cu, Fe, and Co respectively. The corresponding limit of quantification (blank + 10 s) values are 5.30, 6.20, 8.38, 9.54, 4.22, 4.17, 8.62, and 9.86 µg L^?1, respectively. The enrichment on AXAD‐16‐DHP coupled with monitoring by flame atomic absorption spectrometry (FAAS) is used to determine these metal ions in river and synthetic water samples, Co in vitamin tablets, and Zn in milk samples. AXAD‐16‐DHP has been found to perform better than DHP loaded cellulose and Amberlite XAD‐2.     

Removal of aqueous toxic Hg(II) by functionalized mesoporous silica materials

BACKGROUND: Hg(II) is one of the most toxic metals and has received particular attention in environmental pollution. Hg(II) pollution is common in water sources, so rapid and efficient methods must be developed for its removal from water samples. Mesoporous silica (MS) is an ideal adsorbent due to its high surface area and biocompatibility. The efficiency and selectivity of MS adsorbents can be improved by surface modification. RESULTS: A new sorbent for trace Hg(II) removal was developed by grafting 1‐(3‐carboxyphenyl)‐2‐thiourea (CPTU) onto SBA‐15 mesoporous silica. The optimum pH range for Hg(II) adsorption was 3‐7 and the maximum static adsorption capacity was 64.5 mg g^?1. An enrichment factor of 150 was obtained with a relative standard deviation < 1.5% (n = 8). Common coexisting ions did not interfere with the adsorption of Hg(II) under optimal conditions. Quantitative recovery was achieved by stripping with a mixed solution of 1 mol L^?1 HCl and 5% CS(NH₂)₂. Efficient adsorption capacity of the recycled material could still be maintained at a level of 95% at the 7th cycle. CONCLUSION: 1‐(3‐carboxyphenyl)‐2‐thiourea functionalized SBA‐15 mesoporous silica was synthesized and applied for Hg(II) removal from water samples with high efficiency and selectivity. Copyright © 2012 Society of Chemical Industry     

Magnetite‐loaded calcium‐alginate (MLCA) particles as potential sorbent for removal of Ni(II) from aqueous solution

This work is focused on the removal of Ni(II) from aqueous solutions by sorption onto newly developed magnetite‐loaded calcium alginate particles. The uptake of Ni(II) by these magnetite particles, with their mean geometrical diameter 84 and 508 μm, is best described by the Freundlich isotherm and the constants K_F and 1/n were found to be 3.491 mg g^?1, 0.731 and 0.793 mg g^?1 and 0.907, respectively. The mean sorption energy, as determined by Dubinin‐Radushkevich isotherm for 508‐ and 84‐μm sized particles was evaluated to be 8.9 and 8.0 kJ mol^?1, respectively, thus, suggesting the ion‐exchange mechanism for uptake process. Of the various kinetic models proposed, the kinetic Ni(II)‐uptake data were best interpreted by “Simple Elovich” and “Power function” as suggested by their higher regression values. The almost linear nature of plots of log(% sorption) versus log(time) was indicative of intraparticle diffusion. The values of intraparticle diffusion coefficients K_id were found to be 63.49 × 10^?2 and 94.35 × 10^?2 mg l^?1 min^0.5. The intraparticle diffusion was also confirmed by Bangham equation. Finally, various thermodynamic parameters were evaluated. The negative ΔG° indicated spontaneous nature of uptake process while positive ΔH° value suggested exothermic nature of the sorption process. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Pilot plant biosorption in an integrated contact–settling system: application to Cu(II) removal by anaerobically digested sludge

Surplus biological sludge can be used as a low‐cost adsorbent in the removal of heavy metal from wastewater. A three‐zone contact–settling pilot plant was designed and operated to maintain continuous sludge–metal solution contact and subsequent separation of solid–liquid phases, all in the same vessel. Mild agitation was used to ensure good contact between Cu(II) and sludge without impairing solid–liquid separation. Heavy metal removal efficiency was largely unaffected by an increase in the Cu/sludge feed ratio as long as metal binding sites in the sludge remained unsaturated. Maximum metal uptake (75 mg Cu(II) g^?1 of total solids in the sludge) was found for Cu/sludge feed ratios ≥ 90 mg Cu(II) g^?1 of total solids. Pilot plant metal sorption uptake at different operational conditions correlated well with the calculated values from batch equilibrium adsorption isotherms. The amount of Cu(II) adsorbed on sludge influenced the degree of clarification due to the flocculating effect of Cu(II). Under operational conditions, a high degree of heavy metal removal and efficient clarification were achieved. Pilot plant operation at a Cu/sludge feed ratio around 90 mg Cu(II) g^?1 of total solids allowed efficient use of the biosorbent and high heavy metal removal efficiency in addition to a good quality metal‐free effluent in terms of low total suspended solids content. © 2001 Society of Chemical Industry     

Mechanism of copper(II) adsorption by polyvinyl polyacrylate

The mechanism of copper adsorption by polyvinyl polyacrylate (PVPA) was examined using ESR and magnetic measurements. The copper adsorption by PVPA obeyed Langmuir adsorption isotherm with the maximum adsorption amounts of 4.17 mmol g^?1 adsorbent, being larger than those of uranium adsorption. Though copper in the solution was completely adsorbed by the resin above pH 4, the ESR intensity was remained low level and only increased above pH 8. The ESR spectrum of Cu(II) ion in PVPA are axial type with tetragonally distorted octahedral symmetry, having parameters of g_⊥ = 2.361, g_? = 2.057, |A_⊥| = 14.0 m cm^?1 (pH 5), and g_⊥ = 2.329, g_? = 2.058, |A_⊥| = 16.2 m cm^?1, |A_?| = 2.7 m cm^?1 (pH 9). The absorption peaks originated from Cu(II)–Cu(II) dimer was also observed (pH 5). The paramagnetic susceptibility of PVPA adsorbed Cu(II) ion at pH 5 explained by the dimer model with |J| = 220 K. These results suggested that most of copper was adsorbed and formed dimer in PVPA, being similar to that in Cu(II)‐acetate monohydrate. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:5372–5377, 2006     

Biosorption of Zn(II) by orange waste in batch and packed‐bed systems

BACKGROUND: This research provides new insights into the biosorption of zinc on a waste product from the orange juice industry. Optimal operating conditions maximizing percentage zinc removal were determined in batch and fixed‐bed systems. Biomass was characterized by FTIR spectroscopy and by major cation content in order to better understand the biosorpion mechanism. Zn‐loaded orange waste was proposed to be used as an alternative fuel in cement kilns. RESULTS: Sorption capacity was strongly affected by biosorbent dose and solution pH, and was not strongly sensitive to particle size under the experimental conditions studied. Equilibrium data were successfully described by a Langmuir model and sorption kinetic data were adequately modelled with the pseudo‐second‐order and Elovich rate equation. The biomass was found to possess high sorption capacity (q_max = 0.664 mmol g^?1) and biosorption equilibrium was established in less than 3 h. Experimental breakthrough curves were adequately fitted to the Thomas model and the dose–response model, obtaining sorption capacities in continuous assays higher than those found in batch mode. Characterization of the biomass suggested the possible contribution of carboxyl and hydroxyl groups of biomass in Zn²⁺ biosorption and it also highlighted the important role of light metal ions in a possible ion‐exchange mechanism. CONCLUSIONS: Orange waste could be used as an effective and low‐cost alternative biosorbent material for zinc removal from aqueous solution. Copyright © 2010 Society of Chemical Industry     

A novel porous nanocomposite of aminated silica MCM‐41 and nylon‐6: Isotherm,kinetic, and thermodynamic studies on adsorption of Cu(II) and Cd(II)

Porous amine‐modified MCM‐41/Nylon‐6 nanocomposite (NH₂‐MCM‐41/NY6 NC) was synthesized by a facile solution casting protocol, which was used as an effective adsorbent for the removal of Cu(II) and Cd(II) from aqueous media. The physicochemical properties of NH₂‐MCM‐41/NY6 NC were studied by scanning and transmission electron microscopies, thermogravimetric analysis, etc. The influence of pH, adsorbent dose, contact time and initial concentration on adsorption performance were investigated in detail. Kinetic and isotherm parameters were evaluated and the data fitted well to the pseudo‐second order and Freundlich isotherm model, respectively. The maximum adsorption capacities of Cu(II) and Cd(II) were about 35.84 and 27.5 mg·g^?1, respectively. The K_d of NH₂‐MCM‐41/NY6 NC for Cu(II) (> ) and Cd(II) (> ) ions uptake in aqueous solution, showed very good values. Thermodynamic parameters suggest that the adsorption is a spontaneous process with an endothermic nature. According to the results obtained, we conclude that this novel porous NH₂‐MCM‐41/NY6 NC could be used for the removal of heavy metal ions from an aqueous solution. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45383.     

Low temperature one‐step synthesis of poly(barbituric acid) functionalized magnetic nanoparticles for removal of heavy metal ions

Poly(barbituric acid) functionalized magnetic nanoparticles with excellent adsorption behavior were facilely synthesized through one‐step chemical oxidation polymerization method by using sodium borohydride as the reducing agent. Structure, morphology, and magnetism of the products were thoroughly investigated by means of FTIR, FESEM, EDX, X‐ray photoelectron spectra, thermogravimetric analyzer–differential scanning calorimetry, and vibrating sample magnetometer. The products were of a sphere‐shaped nanostructure with the saturation magnetization value of 7.5 emu g^?1, which make them reusable for adsorption application. Removal capability for heavy metal ions were systematically evaluated using Pd (II) and Cu (II) ions as the models. The maximum sorption capacities by applying the Langmuir equation were calculated to be 166.6 mg/g for Cu (II) and 142.8 mg/g for Pb (II). A recycle test revealed that the PBA‐MNPs have above 87.1% for Cu (II) and 82.69% for Pb (II) ion desorption efficiency after the three regeneration cycle process. All the above experimental results demonstrated that barbituric acid‐based material could be used as a possible adsorbent for the efficient removal of heavy metals from aqueous solution. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40957.