Removal of arsenic and selenium compounds from aqueous media by using TiO₂ photocatalytic reaction

A new method for the removal of arsenite [As(III)] and selenate [Se(VI)], which are difficult to remove by conventional water treatment methods from aqueous media, was investigated. This method involves the use of photocatalytic oxidation of As(III) and photocatalytic reduction of Se(VI). Also, a novel TiO₂–adsorbent hybrid (HYB) which has photocatalyst sites and adsorbent sites on the same particle was developed. When the removal of As(III) by use of photocatalyst–adsorbent system and the HYB system was carried out, As(III) was effectively removed from aqueous phase. Moreover, with the removal of Se(VI) by using photocatalytic reduction, Se(VI) could also be removed from aqueous phase under the photocatalyst–adsorbent system and the HYB system, even if the concentration of a hole scavenger formic acid was reduced.