Abstract:The kinetics of the removal of As(III)with zerovalent iron(Fe0)was investigated under N2, air, and O2 purging conditions in well-mixed batch systems at pH values of 4. 0 and 6. 0, and the mechanisms were examined by X-ray absorption fine structure(XAFS)and X-ray diffraction(XRD)and other characterization methods, in order to study the influence of oxygen on the removal of As(III)with Fe0. Although high-concentration oxygen contributed to the oxidation of As(III)to As(V), which could be easily absorbed by iron oxides, the removal of As(III)was more effective under air-purging condition than under O2-purging condition. At a pH value of 4. 0, high-concentration oxygen accelerated the dissolution of Fe0, and thus inhibited the removal of As(III). At a pH value of 6. 0, high-concentration oxygen resulted in passivation of Fe0 and hindered the reaction. In addition, the N2-purging condition totally inhibited the removal of As(III), because iron oxides could hardly be generated under anoxic condition. Therefore, air supplement could be controlled to improve the efficiency of the removal of As(III)with Fe0.