Sonocatalytic degradation of methyl orange in the presence of TiO2 catalysts and catalytic activity comparison of rutile and anatase

Rutile and anatase titanium dioxide (TiO2) powders were used as sonocatalysts for the degradation of methyl orange which was used as a model compound. Ultrasound was used as an irradiation source. It was found that the sonocatalytic degradation ratios of methyl orange in the presence of TiO2 powder were much better than ones without any TiO2, but the sonocatalytic activity of rutile TiO2 particles was obviously higher than that of anatase TiO2 particles. Although there are many factors influencing sonocatalytic degradation of methyl orange, the experimental results show that the best degradation ratio of methyl orange can be obtained when the experimental conditions of the initial methyl orange concentration of 10 mg/l, rutile TiO2 added amount of 500 mg/l, ultrasonic frequency of 40 kHz, output power of 50 W, pH = 3.0 and 40degreesC within 150 min were adopted. In addition, the catalytic activity of reused rutile TiO2 catalyst was also studied and found to be better than new rutile TiO2 catalyst sometimes. All experimental results indicated that the method of the sonocatalytic degradation of organic pollutants in the presence of TiO2 powder was an advisable choice for treating non- or low-transparent organic wastewaters. (C) 2004 Elsevier B.V. All rights reserved.