title: Efficient adsorption of both methyl orange and chromium from their aqueous mixtures using a quaternary ammonium salt modified chitosan magnetic composite adsorbent.
abstract: A quaternary ammonium salt modified chitosan magnetic composite adsorbent (CS-CTA-MCM) was prepared by combination of Fe3O4 nanoparticles. Various techniques were used to characterize the molecular structure, surface morphology, and magnetic feature of this composite adsorbent. CS-CTA-MCM was employed for the removal of Cr(VI) and methyl orange (MO), an anionic dye, from water in respective single and binary systems. Compared with chitosan magnetic adsorbent (CS-MCM) without modification, CS-CTA-MCM shows evidently improved adsorption capacities for both pollutants ascribed to the additional quaternary ammonium salt groups. Based on the adsorption equilibrium study, MO bears more affinity to CS-CTA-MCM than Cr(VI) causing a considerable extent of preferential adsorption of dye over metal ions in their aqueous mixture. However, at weak acidic solutions, Cr(VI) adsorption is evidently improved due to more efficient Cr(VI) forms, i.e. dichromate and monovalent chromate, binding to this chitosan-based adsorbent. Thus chromium could be efficient removal together with MO at suitable pH conditions. The adsorption isotherms and kinetics indicate that adsorptions of Cr(VI) and MO by CS-CTA-MCM both follow a homogeneous monolayer chemisorption process. This magnetic adsorbent after saturated adsorption could be rapidly separated from water and easily regenerated using dilute NaOH aqueous solutions then virtually reused with little adsorption capacity loss.
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, PR China.
authors.forename: Kun
authors.initials: K
authors.lastname: Li
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, PR China.
authors.forename: Pei
authors.initials: P
authors.lastname: Li
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, PR China.
authors.forename: Jun
authors.initials: J
authors.lastname: Cai
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, PR China.
authors.forename: Shoujun
authors.initials: S
authors.lastname: Xiao
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, PR China. Electronic address: yanghu@nju.edu.cn.
authors.forename: Hu
authors.initials: H
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, PR China.
authors.forename: Aimin
authors.initials: A
authors.lastname: Li
mesh_terms: D000327:Adsorption; D001391:Azo Compounds / Q000737:chemistry*; D048271:Chitosan / Q000737:chemistry*; D002857:Chromium / Q000737:chemistry*; D052203:Ferrosoferric Oxide / Q000737:chemistry; D007700:Kinetics; D053768:Metal Nanoparticles / Q000737:chemistry; D015394:Molecular Structure; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D014867:Water / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*
chemical_list: D001391:Azo Compounds; D000644:Quaternary Ammonium Compounds; D014874:Water Pollutants, Chemical; D014867:Water; D002857:Chromium; C100258:methyl orange; D048271:Chitosan; D052203:Ferrosoferric Oxide
keywords: Adsorption mechanism; Chromium; Methyl orange; Quaternary ammonium salt modified chitosan magnetic composite adsorbent; Simultaneous and selective adsorption