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.

Keywords

CaTiO₃ / methylene blue / photocatalytic degradation / kinetics

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