Kinetics of photocatalytic degradation of methylene blue over CaTiO3

Abstract

Kinetics of photocatalytic degradation of methylene blue (MB) over CaTiO3 was studied. Effects of the solution pH, the MB concentration, the CaTiO3 dosage, and the type of light source on photocatalytic degradation rate of MB over CaTiO3 were investigated in detail. The results show that photocatalytic degradation of MB over CaTiO3 followed the first-order reaction. The apparent rate constant (k obs) of MB significantly increased with increasing solution pH while it greatly decreased with increasing MB concentration. The k obs of MB increased with increasing CaTiO3 dosage from 0.05 to 0.1 g, whereas it slightly decreased with increasing CaTiO3 dosage in the range of 0.1-0.4 g. The k obs of MB under UV-visible light irradiation was larger by factors of 2.2 than that under visible light irradiation. The k obs of MB was (4.8±0.3)×10-1 h-1 under optimal conditions with the solution pH of 11, the MB concentration of 1 ppm, the CaTiO3 dosage of 0.1 g, and UV-visible light irradiation.