title: Simultaneous removal of Cu(II) and Cr(VI) by Mg-Al-Cl layered double hydroxide and mechanism insight.
abstract: Mg-Al-Cl layered double hydroxide (Cl-LDH) was prepared to simultaneously remove Cu(II) and Cr(VI) from aqueous solution. The coexisting Cu(II) (20mg/L) and Cr(VI) (40mg/L) were completely removed within 30min by Cl-LDH in a dosage of 2.0g/L; the removal rate of Cu(II) was accelerated in the presence of Cr(VI). Moreover, compared with the adsorption of single Cu(II) or Cr(VI), the adsorption capacities of Cl-LDH for Cu(II) and Cr(VI) can be improved by 81.05% and 49.56%, respectively, in the case of coexisting Cu(II) (200mg/L) and Cr(VI) (400mg/L). The affecting factors (such as solution initial pH, adsorbent dosage, and contact time) have been systematically investigated. Besides, the changes of pH values and the concentrations of Mg2+and Al3+in relevant solutions were monitored. To get the underlying mechanism, the Cl-LDH samples before and after adsorption were thoroughly characterized by X-ray powder diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. On the basis of these analyses, a possible mechanism was proposed. The coadsorption process involves anion exchange of Cr(VI) with Cl-in Cl-LDH interlayer, isomorphic substitution of Mg2+with Cu2+, formation of Cu2Cl(OH)3precipitation, and the adsorption of Cr(VI) by Cu2Cl(OH)3. This work provides a new insight into simultaneous removal of heavy metal cations and anions from wastewater by Cl-LDH.
authors.affiliation: Key Laboratory of Design and Assembly of Functional Nanostructures, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fujian 350002, China.
authors.forename: Xianyang
authors.initials: X
authors.lastname: Yue
authors.affiliation: School of Environment and Energy, South China University of Technology, Guangdong 510006, China. Electronic address: weizhliu@scut.edu.cn.
authors.forename: Weizhen
authors.initials: W
authors.lastname: Liu
authors.affiliation: Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, SA 5095, Australia.
authors.forename: Zuliang
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Key Laboratory of Design and Assembly of Functional Nanostructures, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fujian 350002, China; School of Environment and Energy, South China University of Technology, Guangdong 510006, China. Electronic address: zlin@fjirsm.ac.cn.
authors.forename: Zhang
authors.initials: Z
authors.lastname: Lin
mesh_terms: D002857:Chromium / Q000032:analysis / Q000737:chemistry*; D003300:Copper / Q000032:analysis / Q000737:chemistry*; D006878:Hydroxides / Q000737:chemistry; D007700:Kinetics; D019216:Metals, Heavy; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D006878:Hydroxides; D019216:Metals, Heavy; D014874:Water Pollutants, Chemical; D002857:Chromium; D003300:Copper
keywords: Adsorption; Anion exchange; Heavy metals; Layered double hydroxide; Precipitation