Sonocatalytic degradation of organic dyes and comparison of catalytic activities of CeO2/TiO2, SnO2/TiO2 and ZrO2/TiO2 composites under ultrasonic irradiation

The CeO2/TiO2, SnO2/TiO2 and ZrO2/TiO2 composites were prepared by dispersing various nano-sized oxides (CeO2, SnO2, ZrO2 and TiO2) with ultrasound and mixing TiO2 with CeO2, SnO2 and ZrO2, respectively, in boiling water in a molar ratio of 4:1, followed by calcining temperature 500 °C for 60 min. Then a series of sonocatalytic degradation experiments were carried out under ultrasonic irradiation in the presence of CeO2/TiO2, SnO2/TiO2 and ZrO2/TiO2 composites and nano-sized TiO2 powder. Also, the influences of heat-treatment temperature and heat-treatment time on the sonocatalytic activities of CeO2/TiO2, SnO2/TiO2 and ZrO2/TiO2 composites, and of irradiation time and solution acidity on the sonocatalytic degradation of Acid Red B were investigated by UV–vis spectra. It was found that the sonocatalytic degradation of Acid Red B shows significant variation in rate and ratio that decreases in order: CeO2/TiO2 > SnO2/TiO2 > TiO2 > ZrO2/TiO2 > SnO2 > CeO2 > ZrO2, and the corresponding ratios of Acid Red B in aqueous solution are 91.32%, 67.41%, 65.26%, 41.67%, 28.34%, 26.75% and 23.33%, respectively. And that the degradation ratio is only 16.67% under onefold ultrasonic irradiation. Because of the good degradation efficiency, this method may be an advisable choice for the treatment of non- or low-transparent wastewaters in the future.