Photocatalytic oxidation of aniline using Ag+-loaded TiO2 suspensions

The photocatalytic decomposition of aniline has been investigated using Ag+-loaded TiO2 suspensions as a sensitizer. The amounts of aniline, Ag+ and TiO2 have been optimized by following the rates of decomposition of aniline and formation of product(s). The iritial consumption of aniline follows pseudo-first-order kinetics. The loading of 0.2 wt.% of Ag+ almost doubled this rate compared to that of the unmodified particles. The increased activity of these particles has been attributed to the modified surface properties of TiO2 due to the presence of Ag/Ag+ on its surface, which may act as a trap for electrons and, thereby, inhibit the e(-)-h(+) recombination. Azobenzene has been found to be one of the main products of its oxidation. Its formation has been explained by the direct participation of holes in the oxidation process. Under the used experimental conditions, aniline could be completely decomposed in about 10 h. The addition of Na2CO3 to Ag+-loaded TiO2 suspensions enhances the photodecomposition of aniline significantly. Mechanisms of these processes are discussed. (C) 2004 Elsevier B.V. All rights reserved.