title: The oxidative transformation of sodium arsenite at the interface of alpha-MnO2 and water.
abstract: Arsenite is acute contaminant to human health in soil and water environment. In this study, Pyrolusite (alpha-MnO(2)) was used to investigate the oxidative transformation of arsenite into arsenate with batch experiments under different reaction conditions. The results showed that arsenite transformation occurred and was accompanied by the adsorption and fixation of both As(III) and As(V) on alpha-MnO(2). About 90% of sodium arsenite (10mg/L) were transformed by alpha-MnO(2) under the conditions of 25 degrees C and pH 6.0, 36.6% of which was adsorbed and 28.9% fixed by alpha-MnO(2). Increased alpha-MnO(2) dosages promoted As (III) transformation rate and adsorption of arsenic species. The transformation rate and adsorption of arsenic species raised with increasing pH values of reaction solution from 4.7 to 8.0. The oxidation rate decreased and adsorbed As(III) and As(V) increased with increasing initial arsenite concentration. The enhancement on oxidative transformation of sodium arsenite may result from abundant active sites of alpha-MnO(2). Along with adsorption and fixation of arsenic species during the reaction, the crystal structure of alpha-MnO(2) did not change, but the surface turned petty and loosen. Our results demonstrated that alpha-MnO(2) has important potential in arsenic transformation and removal as the environmentally friendly natural oxidant in soil and surface water.
authors.affiliation: Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, PR China.
authors.forename: Xiu-juan
authors.initials: XJ
authors.lastname: Li
authors.forename: Cheng-shuai
authors.initials: CS
authors.lastname: Liu
authors.forename: Fang-bai
authors.initials: FB
authors.lastname: Li
authors.forename: Yong-tao
authors.initials: YT
authors.lastname: Li
authors.forename: Li-jia
authors.initials: LJ
authors.lastname: Zhang
authors.forename: Chuan-ping
authors.initials: CP
authors.lastname: Liu
authors.forename: Yong-zhang
authors.initials: YZ
authors.lastname: Zhou
mesh_terms: D018053:Arsenites / Q000737:chemistry*; D002021:Buffers; D006863:Hydrogen-Ion Concentration; D007202:Indicators and Reagents; D017895:Manganese Compounds / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D010084:Oxidation-Reduction; D010087:Oxides / Q000737:chemistry*; D017670:Sodium Compounds / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D014867:Water / Q000737:chemistry*; D018508:Water Purification
chemical_list: D018053:Arsenites; D002021:Buffers; D007202:Indicators and Reagents; D017895:Manganese Compounds; D010087:Oxides; D017670:Sodium Compounds; D014867:Water; C017947:sodium arsenite; C027424:manganese oxide