Heterocyclic modification of chitosan for the adsorption of Cu (II) and Cr (VI) ions

A heterocyclic modification of chitosan has been attempted for development of an effective adsorbent material for removal of metal ions. The modified polymer was characterized using infrared (IR) spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS) and x-ray diffraction (XRD) techniques. The adsorption capacity exhibited for Cu (II) and Cr (VI) were 83.75 and 85.0 mgg^?1, respectively, which is a significant improvement over chitosan. The adsorption on the modified polymer was a second-order kinetic process and followed Langmuir isotherm model. The thermodynamic analysis indicated exothermic and spontaneous nature of adsorption. About 80% of the adsorbed metal ions were desorbed in appropriate stripping solutions indicating reusability.     

O-carboxymethyl functionalization of chitosan: Complexation and adsorption of Cd (II) and Cr (VI) as heavy metal pollutant ions

Chitosan (CHI) is a biopolymer that can be used on complexation and adsorption of heavy metals in water. Chitosan can be chemically functionalized to modulate the pH range of solubility and favoring the complexation and adsorption processes with metal ions. Thus, in this study, it was investigated the synthesis and characterization of carboxymethyl-chitosan (CMC) as well as its application for the complexation and adsorption of Cd(II) and Cr(VI) ions at different pH conditions and compared to pristine chitosan. The properties of the synthesized derivative were extensively characterized by potentiometric titration, Fourier transform infrared spectroscopy (FTIR) and ultraviolet–visible (UV–vis) spectroscopy. The complexation and adsorption behaviors of CHI and CMC were assessed using atomic absorption spectrometer (AAS) and zeta potential analysis. The results demonstrated that O-carboxymethylation of chitosan has occurred with a degree of functionalization higher than 50% leading to the formation of CMC soluble in alkaline medium. In addition, the effective incorporation of carboxylic groups in the chitosan chain (CMC) has significantly altered the complexation and adsorption responses towards heavy metal cations (Cd^2 +) and anions (chromates) as compared to CHI. Therefore, these systems offer an attractive alternative as biosorbents for the removal of heavy metal pollutants from the wastewater.     

Adsorption of cadmium (II) and copper (II) ions from aqueous solution using chitosan composite

The binary chitosan/silk fibroin composite synthesized by reinforcement of silk fibroin fiber into the homogenous solution of chitosan in formic acid was used to investigate the adsorption of two metals of Cu(II) and Cd(II) ions in an aqueous solution. The binary composite was characterized by Fourier transform infrared and scanning electron microscopy. The optimum conditions for adsorption by using a batch method were evaluated by changing various parameters such as contact time, adsorbent dose, and pH of the solution. The experimental isotherm data were analyzed using the Freundlich and Langmuir equations, indicated to be well fitted to the Langmuir isotherm equation under the concentration range studied, by comparing the correlation co‐efficient. Adsorption kinetics data were tested using pseudo‐first‐order and pseudo‐second‐order models. Kinetics studies showed that the adsorption followed a pseudo‐second‐order reaction. Due to good performance and low cost, this binary chitosan/silk fibroin composite can be used as an adsorbent for removal of Cu(II) and Cd(II) from aqueous solutions. POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers     

Fixed-bed column study on removal of Mn(II), Ni(II) and Cu(II) from aqueous solution by surfactant bilayer supported alumina

In the present work, the potential of modified alumina for the removal of heavy metals such as Mn(II), Ni(II) and Cu(II) was evaluated in a fixed-bed column operation. The effects of bed depth, flow rate and initial concentration on the removal of Mn(II), Ni(II) and Cu(II) were investigated at the optimum pH. The modified alumina was found to be very efficient for the removal of such heavy metals from water environment. Bed depth service time (BDST) model was best fitted to adsorption data. The theoretical and experimental breakthrough curves were comparable for all heavy metals.     

Removal of Cd(II), Hg(II), and Pb(II) ions from aqueous solution using p(HEMA/chitosan) membranes

An interpenetration network (IPN) was synthesized from 2‐hydroxyethyl methacrylate (HEMA) and chitosan, p(HEMA/chitosan) via UV‐initiated photo‐polymerization. The selectivity to different heavy metal ions viz Cd(II), Pb(II), and Hg(II) to the IPN membrane has been investigated from aqueous solution using bare pHEMA membrane as a control system. Removal efficiency of metal ions from aqueous solution using the IPN membranes increased with increasing chitosan content and initial metal ions concentrations, and the equilibrium time was reached within 60 min. Adsorption of all the tested heavy metal ions on the IPN membranes was found to be pH dependent and maximum adsorption was obtained at pH 5.0. The maximum adsorption capacities of the IPN membrane for Cd(II), Pb(II), and Hg(II) were 0.063, 0.179, and 0.197 mmol/g membrane, respectively. The adsorption of the Cd(II), Hg(II), and Pb(II) metal ions on the bare pHEMA membrane was not significant. When the heavy metal ions were in competition, the amounts of adsorbed metal ions were found to be 0.035 mmol/g for Cd(II), 0.074 mmol/g for Hg(II), and 0.153 mmol/g for Pb(II), the IPN membrane is significantly selective for Pb(II) ions. The stability constants of IPN membrane–metal ions complexes were calculated by the method of Ruzic. The results obtained from the kinetics and isotherm studies showed that the experimental data for the removal of heavy metal ions were well described with the second‐order kinetic equations and the Langmuir isotherm model. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Pb(II) biosorption using DAP/EDTA-modified biopolymer (Chitosan)

Abstract

In this study, chitosan was chemically modified with only diammonium phosphate (DAP) and DAP/EDTA (ethylenediaminetetraacetic acid) mixture for the removal of Pb(II) ions from aqueous solution. Modified chitosan forms were analyzed using thermo-gravimetric analyzer (TGA), Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM) to investigate the thermal degradation behavior, structural modifications, and the surface texture of the cross-linked chitosan adsorbents, respectively. The adsorption results were analyzed by well-known kinetic and isotherm models. The kinetics of metal adsorption followed the pseudo-second-order model. The maximum sorption capacities obtained from the Langmuir isotherm model were 126?mg/g for diammonium phosphate-modified Chitosan (DMC) and 137?mg/g for DAP/EDTA-modified chitosan (EDMC). The thermodynamic analysis showed that the metal removal process was endothermic in nature.     

Chitosan nanoparticles extracted from shrimp shells,application for removal of Fe(II) and Mn(II) from aqueous phases

ABSTRACT

The present work aims to prepare an ecofriendly and effective material for adsorption of heavy metals, especially iron and manganese from polluted water. Chitosan nanoparticles were prepared from the extracted chitosan of shrimp shells waste using a traditional ionic gelation method in presence of sodium tripolyphosphate as a cross-linker. To confirm the polymer structure and its characteristics, the prepared nanoparticles were characterized using FT-IR, X-Ray diffraction, TEM and SEM. Molecular weight, the degree of de-acetylation, ash content, particle size and zeta potential values were 3923 D, 75 %, 4 %, 331 nm and +38 mv, respectively. A batch equilibrium experiments were carried out to evaluate the chitosan nanoparticles as adsorbents of Fe (II) and Mn (II) ions from aqueous solutions. The removal efficiency and adsorption capacity were studied at different contact times, pH of the sorption medium, and initial metal ion concentration in the feed solution. The removal efficiency and maximum adsorption capacity of Fe (II) and Mn (II) were 99.8, 116.2 mg/g and 95.3%, 74.1mg/g, respectively. From the adsorption isotherm and kinetic studies, it was found that the Langmuir and the pseud-second order models, respectively, were more fitted in this study.     

Removal of copper(II) ions from aqueous solution onto chitosan and cross-linked chitosan beads

The adsorption of Cu(II) ions onto chitosan and cross-linked chitosan beads has been investigated. Chitosan beads were cross-linked with glutaraldehyde (GLA), epichlorohydrin (ECH) and ethylene glycol diglycidyl ether (EGDE) in order to obtain sorbents that are insoluble in aqueous acidic and basic solution. Batch adsorption experiments were carried out as a function of pH, agitation period, agitation rate and concentration of Cu(II) ions. A pH of 6.0 was found to be a optimum for Cu(II) adsorption on chitosan and cross-linked chitosan beads. Isotherm studies indicate Cu(II) can be effectively removed by chitosan and cross-linked chitosan beads. Adsorption isothermal data could be well interpreted by the Langmuir equation. Langmuir constants have been determined for chitosan and cross-linked chitosan beads. The experimental data of the adsorption equilibrium from Cu(II) solution correlated well with the Langmuir isotherm equation. The uptakes of Cu(II) ions on chitosan beads were 80.71 mg Cu(II)/g chitosan, on chitosan-GLA beads were 59.67 mg Cu(II)/g chitosan-GLA, on chitosan-ECH beads were 62.47 mg Cu(II)/g chitosan-ECH and on chitosan-EGDE beads were 45.94 mg Cu(II)/g chitosan-EGDE. The Cu(II) ions can be removed from the chitosan and cross-linked chitosan beads rapidly by treatment with an aqueous EDTA solution and at the same time the chitosan and cross-linked chitosan beads can be regenerated and also can be used again to adsorb heavy metal ions.     

Adsorption of Cu(II) and Ni(II) using a Novel Xanthated Carboxymethyl Chitosan

Removal of Cu(II) and Ni(II) from aqueous solutions by a novel xanthated carboxymethyl chitosan (XCC) was investigated. XCC obtained was characterized by FTIR, SEM, EDX, and XRD. The adsorption ability of chitosan and XCC toward Cu(II) and Ni(II) was compared. The effect of pH (2.0–7.0), contact time (5–60 min), and adsorption isotherms on adsorption were also investigated. It was observed that the modified chitosan XCC showed a remarkable increase in Cu(II) and Ni(II) adsorption as compared to chitosan and displayed a quick adsorption performance. Further, The Langmuir isotherm was found to provide the best correlation of the experimental data and the adsorption capacity obtained from the Langmuir model was 174.2 mg/g and 128.4 mg/g for Cu(II) and Ni(II), respectively. FTIR and UV spectra suggested that the amino groups, carboxyl groups, and xanthate groups of XCC participated in the adsorption.     

Facile preparation of EDTA‐functionalized chitosan magnetic adsorbent for removal of Pb(II)

A novel magnetic adsorbent (EDTA /chitosan/ PMMS) was facilely prepared by reacting chitosan with EDTA anhydride in presence of PEI ‐ coated magnetic microspheres. The as‐synthesized EDTA/ chitosan /PMMS was characterized by XRD, SEM, TGA, FT‐IR , and VSM, and then employed in removal of heavy metals of Pb(II) from aqueous solution. The results of the batch adsorption experiments revealed that the adsorbents had extremely high uptake capacities for Pb(II) in the pH range of 2 to 5.5, and the adsorption kinetics for EDTA/ chitosan /PMMS was consistent with the pseudo – second ‐ order kinetic model. Moreover, its equilibrium data were fitted with the Langmuir isothermal model well, which indicated that the adsorption mechanism was a homogeneous monolayer chemisorptions process. The maximum adsorption capacity of EDTA/ chitosan /PMMS for Pb(II) was found to be 210 mg g ^{? 1} at pH 4 (30 ° C), and further reuse experiments results suggested that EDTA /chitosan/ PMMS could be a potential recyclable magnetic adsorbent in the practical wastewater treatment. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42384.     

Preparation,characterization, and adsorption properties of chitosan microspheres crosslinked by formaldehyde for copper (II) from aqueous solution

The chitosan microspheres crosslinked by formaldehyde were prepared by spray drying method and used as an adsorbent for copper (II) from aqueous solution. A batch adsorption system was applied to study the adsorption of copper (II) from aqueous solution by chitosan microspheres. The maximum adsorption capacity of the chitosan microspheres for copper (II) was 144.928 mg/g at pH 6.0. Langmuir adsorption model was found to be applicable in interpreting the adsorption process. To elucidate the adsorption mechanism, the chitosan microspheres before and after copper (II) adsorption were further characterized by Fourier transform infrared spectra, zeta potential analysis, and scanning electron microscope. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Recent studies in adsorption of Pb(II), Zn(II) and Co(II) using conventional and modified materials:a review

ABSTRACT

Heavy metal contamination and its detrimental effects on human health and environment have been a worldwide concern. Over the years, various technologies have been adapted to tackle this problem. Adsorption is still considered to be one of the most feasible and cost-effective methods for treating wastewater contaminated with heavy metals. Adsorbents such as activated carbon, clay, zeolites and silica have been studied extensively in the past. Modification of these conventional adsorbents and the synthesis of nonconventional adsorbents such as nanocomposites and metal organic frameworks (MOF’s) have been the main focus of study in recent times. This review article attempts to present a detailed account of various adsorbents and their removal efficiencies for the treatment of wastewater contaminated with lead(II), zinc(II) and cobalt(II) in the current decade. Influence of various parameters, adsorption isotherms and kinetics best described for their removal have also been reviewed in detail. It is observed that most of the adsorbents followed pseudo second order kinetics suggestive of a chemisorption process. After conducting a thorough review of more than 120 recently published papers, it can be inferred that nanomaterials and nanocomposites have shown excellent adsorption capacity for removal of these heavy metals.     

Adsorption of Pb(II) Ions Using Humic Acid Coated Chitosan-Tripolyphosphate (HA-CTPP) Beads

A new humic acid (HA) based adsorbent was prepared by coating humic acid on chitosan tripolyphosphate (CTPP) beads. Humic acid-chitosan tripolyphosphate (HA-CTPP) beads thus obtained were characterized using Fourier Transform Infrared Spectroscopy and Scanning Electron Microscopy. Swelling capacity studies of CTPP and HA-CTPP beads conducted in the pH range, pH = 1–10 showed that HA-CTPP beads are more stable against swelling than CTPP beads. Equilibration of HA-CTPP beads in water for different pH showed that leaching of HA from the beads is negligible and the beads are stable for adsorption applications. Adsorption of Pb(II) ions onto HA-CTPP beads were studied as a function of various operational parameters such as initial pH, metal ion concentration, and contact time. The results showed that HA-CTPP beads are suitable for Pb(II) ions adsorption and the kinetics of sorption very well fit into pseudo-second order model. The Langmuir model was found to be more suitable for explaining the observed adsorption data, giving a theoretical maximum adsorption capacity of 223.7 mg/g. HA-CTPP beads could possibly find application in the treatment of waste water contaminated with other toxic and/or heavy metals.     

Preparation of magnetic graphene oxide/chitosan composite beads for effective removal of heavy metals and dyes from aqueous solutions

In this report, a composite adsorbent in form of spherical beads generated from graphene oxide, chitosan, and magnetite (MGOCS) was developed and characterized by X-ray powder diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscope, and vibrating sample magnetometer. The adsorption ability of MGOCS towards reactive blue 19 (RB19) and Ni(II) ions, and the effect of various experimental factors including pH, adsorbent dosage, contact time, adsorbate concentration, temperature, and ionic strength were assessed in detail. The maximum adsorption capacities of MGOCS were 102.06?mg/g for RB19 and 80.48?mg/g for Ni(II). The adsorption process was thermodynamically favorable, spontaneous, exothermic, and best described by Langmuir (for Ni(II)) and Freundlich (for RB19) isotherms. The adsorption kinetics were well fitted with pseudo-first-order model for both adsorbates. The result indicated that the beads have feasibility as highly efficient and eco-friendly adsorbent to get rid of organic dyes and heavy metals from water due to their high adsorption capacity, easy recovery, and reusability.     

Adsorption of Biodegradable Polyelectrolyte onto Cotton for Fixation of Copper and Lead: Comparison to a Cation Exchange Textile

In order to develop fibrous materials for treatment of waste water and industrial effluents, cotton and Cation Exchange Textiles (CET) were used as supports. Their modification with the biodegradable positive polyelectrolyte (chitosan) improved performance for the fixation of heavy metals such as copper and lead. The influence of the amine group of chitosan on the anionic sites of textiles has been investigated. The adsorption isotherms were applied according to Freundlich and Langmuir models. No physical damage of the adsorbents was observed after seven cycles of adsorption/desorption using EDTA and HCl as eluents. The cation exchange capacity, pH, adsorption rate, and adsorption kinetics were also studied. The mechanical pathways of Pb(II) and Cu(II) uptake were examined by means of Fourier transform infrared (FTIR). The regeneration of the modified textiles (cotton and CET) with chemical reagents was satisfactory, but much less under the application of an electric field, because of complex phenomenon. Nevertheless, the membrane electroextraction of metal from CET still remains efficient since it obeys the ionic exchange process.     

Studies on the sorption capacity for Pb(II) and Hg(II) of citralidene chitosan

Citralidene chitosan, prepared by condensation of citral and chitosan, was characterized by infrared spectroscopy, scanning electron microscopy and differential scanning calorimetry and evaluated for its Pb(II) and Hg(II) sorption capacity. The contact time for Pb(II) and Hg(II) sorption was found to be 5 and 4 h, respectively. The sorption data best fitted to pseudo second-order equation. The equilibrium sorption data were found to be best fitted to Langmuir model. The studies revealed that the citralidene chitosan has different binding sites and the sorption was spontaneous and exothermic. Citralidene chitosan was found to be an efficient and cheap sorbent for Pb(II) and Hg(II).     

[Dye molecules/copper(II)/macroporous glutaraldehyde‐chitosan] microspheres complex: Surface characterization,kinetic, and thermodynamic investigations

Chitosan microspheres loaded Cu(II) were prepared using a precipitation method and heterogeneously crosslinked with glutaraldehyde. The abilities of the binary [Cu(II)/Glut‐chitosan] system for binding two acid dyes, that is, Acid blue 25 (AB25) and Calmagite (Calma) were investigated. Sorption experiments were performed using a batch process at 25°C and indicate pH dependence. Evidence for the modification of the raw chitosan polymer was provided by Fourier transform infra red spectral study, thermogravimetry, differential thermogravimetry, differential scanning calorimetry, and scanning electron microscopy analysis. Data gleaned from the thermal analyses, showed that the modification of the polymer decreases the thermal stability of the prepared materials with respect to that of the native one. The effecting factors during dye adsorption have been also studied. Thermodynamic and kinetic experiments were undertaken to assess the capacity and the rate of dyes removal on the surface of [Cu(II)/Glut‐chitosan]. Experimental data were mathematically described using various kinetic models. The pseudo second‐order equation was shown to fit the adsorption kinetics. The interpretation of the equilibrium sorption data complies well with the Freundlich adsorption model. Thermodynamic results indicate that the adsorption follows an exothermic process. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Bioadsorption of Pb(II), Cd(II), and Cr(VI) on activated carbon from aqueous solutions

The bioadsorption of Pb(II), Cd(II), and Cr(VI) using bacteria and activated carbon has been studied. Preliminary studies yielded the chemical and textural characterization of the carbons. The adsorption of bacteria on the activated carbons modified their surface characteristics, reducing the volume of pores and the pH of the point of zero charge, with a resulting increase in the density of the negative charge of their surface. The adsorption of the above metals was studied in both static and dynamic conditions and in the absence and presence of bacteria (Escherichia coli). The presence of bacteria in aqueous solution enhances the adsorption of Pb(II) and Cd(II) and reduces the adsorption of Cr(VI). These results can be explained by changes in the surface charge density of the carbons when bacteria are adsorbed, and by considering the structural and chemical characteristics of the bacterial cell walls. Investigation of the effect of electrolytes on the bioadsorption of these metals showed, in general, a resulting reduction in the amount of metal adsorbed, mainly in the presence of divalent cations. According to the divalent cation bridging theory, these results derive from competition between the Pb(II) or Cd(II) cations and the electrolyte cations for the negatively charged functional groups of extracellular polymeric substances.     

Removal of copper(II) from an aqueous solution with copper(II)‐imprinted chitosan microspheres

Ion‐imprinted chitosan (CS) microspheres (MIPs) were prepared with Cu(II) as a template and epichlorohydrin as a crosslinker for the selective separation of Cu(II) from aqueous solution. The microspheres showed a higher adsorption capacity and selectivity for the Cu(II) ions than nonimprinted chitosan microspheres (NMIPs) without a template. The results show that the adsorption of Cu(II) on the CS microspheres was affected by the initial pH value, initial Cu(II) concentration, and temperature. The kinetic parameters of the adsorption process indicated that the adsorption followed a second‐order adsorption process. Equilibrium experiments showed very good fits with the Langmuir isotherm equation for the monolayer adsorption process. The maximum sorption capacity calculated from the Langmuir isotherm was 201.66 mg/g for the Cu–MIPs and 189.51 mg/g for the NMIPs; these values were close to the experimental ones. The selectivity coefficients of Cu(II) and other metal ions on the NMIPs indicated a preference for Cu(II). © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013