The oxidative transformation of sodium arsenite at the interface of alpha-MnO2 and water.
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.
Li
Xiu-juan
XJ
Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, PR China.
Liu
Cheng-shuai
CS
Li
Fang-bai
FB
Li
Yong-tao
YT
Zhang
Li-jia
LJ
Liu
Chuan-ping
CP
Zhou
Yong-zhang
YZ
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
D018053:Arsenites; D002021:Buffers; D007202:Indicators and Reagents; D017895:Manganese Compounds; D010087:Oxides; D017670:Sodium Compounds; D014867:Water; C017947:sodium arsenite; C027424:manganese oxide