Removal of bromate ion from water using TiO2 and alumina-loaded TiO2 photocatalysts

The effects of pH and the surface charge of photocatalyst on photocatalytic reduction of bromate ions in water were examined by using TiO₂ and alumina-loaded TiO₂ photocatalysts. The amount of adsorbed bromate ion on TiO₂ and the reduction rate of bromate ion by the TiO₂ photocatalyst increased with lowering pH. It was suggested that the bromate ion adsorbed predominantly on the positively charged surface sites of TiO₂ at lower pH, which thus promotes the rate of reduction. The iso-electric point of the TiO₂ photocatalyst was shifted to the higher pH region by loading alumina on the TiO₂ surface, which resulted in the increase of the adsorbed amount of bromate on the photocatalyst and the reduction rate of bromate ion by the photocatalyst at neutral pH. It was concluded from these results that the photocatalytic reduction of bromate ion can be promoted by pH control of water or by controlling the surface charge of the photocatalyst by loading alumina without pH control of water.