| 초록 |
The oxidation of arsenite (As(III)), which is a critical pre-treatment process for total arsenic removal, is easily achieved using chemical oxidants. Among various oxidants, hydrogen peroxide (H2O2) is an environmentally benign oxidant. However, its practical use is limited by the pH dependent oxidation kinetics. This study demonstrated the efficient catalytic oxidation of As(III) using metal oxides and H2O2 over a wide working pH range. Among metal oxides, TiO2 is an ideal catalyst since it is not only active and stable but also inexpensive. The heterogeneous oxidation was enhanced with increasing the TiO2 surface area and [H2O2], and it was weakly dependent on pH. On the other hand, the homogeneous oxidation by H2O2 was favored only at alkaline condition. The oxidation rate was not reduced at all by OH radical scavengers but markedly retarded by hydroperoxyl radical scavengers. It is proposed that the surface complexation of H2O2 with TiO2 surface causes the generation of the surface hydroperoxyl radical through an inner-sphere electron transfer, which subsequently oxidizes As(III). |
