Effects of pH and surface modification of TiO 2 with SiO x on the photocatalytic degradation of a pyrimidine derivative

Abstract

A pyrimidine derivative, 2-isopropyl-6-methyl-4-pyrimidinol (IMP), could be completely decomposed following pseudo-first-order kinetics by photocatalytic reaction using TiO 2. The effects of pH and surface modification of TiO 2 with SiO x were studied. The degradation rate of IMP was fast in mild acidic condition (pH=6.3) and slower in strong acidic (pH=2.0) or basic (pH=10.0) condition. The main reason of the slow IMP degradation was different in strong acidic and basic conditions. In strong acidic condition, the slow degradation rate was explained by electrostatic repulsion. On the other hand, a little formation of hydroxyl radicals was considered as a main reason in strong basic condition. The result was supported by the experiments using SiO x -loaded TiO 2, which has a lower isoelectric point than pure TiO 2.