title: Enhanced sequestration of Cr(VI) by nanoscale zero-valent iron supported on layered double hydroxide by batch and XAFS study.
abstract: Herein, the reduction of nanoscale zero-valent iron (NZVI) and adsorption of layered double hydroxides (LDH) to sequester Cr(VI) were well combined by the immobilization of NZVI onto LDH surface (NZVI/LDH). The characterization results revealed that LDH decreased NZVI aggregation and thus increased Cr(VI) sequestration. The batch results indicated that Cr(VI) sequestration by NZVI/LDH was higher than that of NZVI, and superior to the sum of reduction and adsorption. The LDH with good anion exchange property allowed the adsorption of Cr(VI), facilitating interfacial reaction by increasing the local concentration of Cr(VI) in the NZVI vicinity. X-ray absorption near edge structure (XANES) results indicated that Cr(VI) was almost completely reduced to Cr(III) by NZVI/LDH, but Cr(VI) was partly reduced to Cr(III) by NZVI with a trace of Cr(VI) adsorbed on corrosion products. The coordination environment of Cr from extended X-ray absorption fine structure (EXAFS) analysis revealed that LDH could be a good scavenger for the insoluble products produced during reaction. So, the insoluble products on NZVI could be reduced, and its reactivity could be maintained. These results demonstrated that NZVI/LDH exhibits multiple functionalities relevant to the remediation of Cr(VI)-contaminated sites.
authors.affiliation: College of Chemistry and Chemical Engineering, College of Medical Science, Shaoxing University, Zhejiang 312000, PR China; Institute of Plasma Physics, Chinese Academy of Sciences, P.O. Box 1126, Hefei 230031, PR China. Electronic address: gdsheng@usx.edu.cn.
authors.forename: Guodong
authors.initials: G
authors.lastname: Sheng
authors.affiliation: School of Electronic Engineering, Dongguan University of Technology, Guangdong 523808, PR China.
authors.forename: Jun
authors.initials: J
authors.lastname: Hu
authors.affiliation: College of Chemistry and Chemical Engineering, College of Medical Science, Shaoxing University, Zhejiang 312000, PR China.
authors.forename: Hui
authors.initials: H
authors.lastname: Li
authors.affiliation: Institute of Plasma Physics, Chinese Academy of Sciences, P.O. Box 1126, Hefei 230031, PR China.
authors.forename: Jiaxing
authors.initials: J
authors.lastname: Li
authors.affiliation: Shanghai Synchrotron Radiation Facility (SSRF), Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201204, PR China.
authors.forename: Yuying
authors.initials: Y
authors.lastname: Huang
mesh_terms: D000327:Adsorption; D002857:Chromium / Q000032:analysis*; D006878:Hydroxides / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D046529:Microscopy, Electron, Transmission; D008962:Models, Theoretical; D010084:Oxidation-Reduction; D010316:Particle Size; D012995:Solubility; D013499:Surface Properties; D014874:Water Pollutants, Chemical / Q000032:analysis*; D056928:X-Ray Absorption Spectroscopy
chemical_list: D006878:Hydroxides; D014874:Water Pollutants, Chemical; D002857:Chromium; C074702:chromium hexavalent ion; D007501:Iron
keywords: Cr(VI); Layered double hydroxides; Nanoscale zero-valent iron; Synergistic effect; X-ray absorption fine structure (XAFS) spectra