Sonophotocatalytic degradation of methyl orange by nano-sized Ag/TiO2 particles in aqueous solutions

Sonophotocatalytic behaviour of methyl orange (MeO) in aqueous solution illuminated by light generated by a xenon lamp was investigated. For all three kinds of photocatalysts: Degussa P25 (75% anatase, 25% rutile, with a surface area of 55.07 m(2)/g), Yili TiO2 (mainly anatase, with a surface area of 10.45 m(2)/g) and Ag/TiO2 (silver loaded on Yili TiO2), the degradation followed pseudo-first order kinetics. The results showed a synergistic effect between sonolysis and photocatalysis. Some parameters affecting the sonophotocatalytic degradation of MeO with nanoparticles Ag/TiO2 Were determined. The results indicated that the degradation ratio of MeO increased with the increase of ultrasonic power. An optimum 60 mg/L of Ag/TiO2 added to relatively low concentrations of MeO was proved to have the most effective degradation efficiency. The study on the effects of hydroxyl radical ((OH)-O-center dot) scavengers (i.e. mannitol and dimethyl sulfoxide) on the MeO degradation indicated that (OH)-O-center dot radicals played an important role during MeO degradation, which enhanced MeO to be completely decomposed. (C) 2007 Elsevier B.V. All rights reserved.