Controlling And Removal Of Bromate In Drinking Water By Applying Graphene Materials

The controlling and photocatalysis removal of bromate (BrO3-) attract muchattention as BrO3-is a carcinogenic and genotoxic contaminant in drinking water. Inthis paper, the development progresses of bromate controlling and removal methodswere described, the research progressses of Graphene and P25in adsorption andphotocatalysis, photocatalytic mechanism of P25, application problems and the waysof improvements were detailed. These prepared Graphene materials(GR and GO)were obtained by modified Hummers’ method, which were employed to control BrO3-formation in ozone treat process. Simultaneously, TiO2-graphene composite (P25-GR)photocatalyst for BrO3-reduction were prepared by a facile one-step hydrothermalmethod, which exhibited a high capacity of BrO3-removal.In chapter one, a facile modified Hummers’ method has been developed forpreparing GR and GO. P25-GR photocatalysts were obtained by a one-stephydrothermal method. The crystal size, dimension and morphology of the GR and GOwere investigated with TEM, HR-TEM, XRD and Raman. The structure, mass ratioand light adsorption characteristics of P25-GR were collected by XRD, Raman, XRFand ect. It was found that the obtained GR and GO were distributed monolayer ormultilayer which were uniform apperance and excellent performance.The P25-GRphotocatalysts had good optical properties and resonable mass ratio.In chapter two, optimizing GR and GO were decimated to reserch the adsorptionperformance for bromate and bromine, controlling formation of bromate in ozonetreat process, and MB removal capability. Through batch experiments,different pH,initial concentration of bromate, dosage of GO and GR were investigated. The resultsshowed that the GR had obvious inhibitory effect for the formation of bromate inozone treat process. The controlling capability of GR was predominantly contributedthat the GR removal the intermediate HOBr to prevent its futher formation.In chapter three, these prepared P25-GR composites were employed asphotocatalyst to reduce BrO3-to Br-under UV light irradiation. The maximum removal of BrO3-was observed in the optimal conductions of1%GR doping and atpH6.8. Compared with that without UV, the higher decreasing of BrO3-on thecomposite indicates that BrO3-decomposition was predominantly contributed tophoto-reduction with UV rather than adsorption. This hypothesis was supported by thedecreasing of [BrO3-] with the synchronous increasing of [Br-] at nearly constantamount of total Bromine ([BrO3-]+[Br-]). Furthermore, the improvement of BrO3-reduction on P25-GR was observed in the treatment of a tap water. However, theefficiency of BrO3-removal was less than that in deionized water, probably due to theconsumption of photo-generated electrons and the adsorption of natural organicmatters (NOM) on graphene.Finally, a concise summary was given and the next study was proposed.