2000 年 41 巻 7 号 p. 799-805
The photocatalytic reduction of aqueous Se(VI) solution was studied using two types of TiO2 powders with different specific surface areas and dispersed particle sizes as a catalyst, and HCOOH as a reductant. The principal reduction products were Se° and H2Se; Se(IV) was not detected. The reduction rate of Se(VI) was mainly controlled by the amount of Se(VI) adsorbed onto each type of the TiO2 powders. When different TiO2 powders were used, the energy conversion ratio of TiO2 played the more important role in the photocatalytic reduction of Se(VI) or Se°. Using a TiO2 catalyst with a high conversion ratio, the time required for the reductions of Se(VI) to Se° and of Se° to H2Se differed by a ratio of 3:1, as expected from reaction equations. The reduction rates for Se(VI) can be approximated from the amount of Se(VI) adsorbed onto TiO2 powders and the energy conversion ratios. The pH of solution, amount of TiO2 and concentrations of Se(VI) and HCOOH were additionaly recognized as important factors.