Photocatalytic decomposition of bromate ion by the UV/P25-Graphene processes.

The photocatalysis of bromate (BrO3(-)) attracts much attention as BrO3(-) is a carcinogenic and genotoxic contaminant in drinking water. In this work, TiO2-graphene composite (P25-GR) photocatalyst for BrO3(-) reduction were prepared by a facile one-step hydrothermal method, which exhibited a higher capacity of BrO3(-) removal than P25 or GR did. The maximum removal of BrO3(-) was observed in the optimal conductions of 1% GR doping and at pH 6.8. Compared with that without UV, the higher decreasing of BrO3(-) on the composite indicates that BrO3(-) decomposition was predominantly contributed to photo-reduction with UV rather than adsorption. This hypothesis was supported by the decreasing of [BrO3(-)] with the synchronous increasing of [Br(-)] at nearly constant amount of total Bromine ([BrO3(-)] + [Br(-)]). Furthermore, the improvement of BrO3(-) reduction on P25-GR was observed in the treatment of a tap water. However, the efficiency of BrO3(-) removal was less than that in deionized water, probably due to the consumption of photo-generated electrons and the adsorption of natural organic matters (NOM) on graphene.