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

The CeO(2)/TiO(2), SnO(2)/TiO(2) and ZrO(2)/TiO(2) composites were prepared by dispersing various nano-sized oxides (CeO(2), SnO(2), ZrO(2) and TiO(2)) with ultrasound and mixing TiO(2) with CeO(2), SnO(2) and ZrO(2), respectively, in boiling water in a molar ratio of 4:1, followed by calcining temperature 500 degrees C for 60 min. Then a series of sonocatalytic degradation experiments were carried out under ultrasonic irradiation in the presence of CeO(2)/TiO(2), SnO(2)/TiO(2) and ZrO(2)/TiO(2) composites and nano-sized TiO(2) powder. Also, the influences of heat-treatment temperature and heat-treatment time on the sonocatalytic activities of CeO(2)/TiO(2), SnO(2)/TiO(2) and ZrO(2)/TiO(2) 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: CeO(2)/TiO(2)>SnO(2)/TiO(2)>TiO(2)>ZrO(2)/TiO(2)>SnO(2)>CeO(2)>ZrO(2), 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.