Investigation on the sonocatalytic degradation of congo red catalyzed by nanometer rutile TiO2 powder and various influencing factors

Nanometer rutile (TiO2) powder was introduced to act as the sonocatalyst during degradation of congo red that was chosen as a model compound. The ultrasound of low power was used as an irradiation source to induce nanometer rutile TiO2 particles performing catalytic activity. It was found that the sonocatalytic degradation ratio of congo red in the presence of nanometer rutile TiO2 particles was much better than ones with onefold ultrasonic irradiation. Although there are many factors influencing sonocatalytic degradation of congo red, the experimental results demonstrate that the optimal degradation effect of congo red can be obtained when the experimental conditions of initial congo red concentration of 10.0 mg/L, nanometer rutile TiO2 adding amount of 1.0-1.5 g/L, ultrasonic frequency of 40 kHz, output power of 50 W, pH = 3.0-5.0 and 50°C within 180 min were adopted. At last, the congo red in aqueous solution was completely degraded and became some simple inorganic ions such as NO3− and SO42− anions, etc. In this paper, the research on kinetics of sonocatalytic reaction has also been performed and found to follow pseudo first-order reaction. All experiments indicated that the sonocatalytic method in the presence of nanometer rutile TiO2 powder was an advisable choice for the treatments of non- or low-transparent organic wastewaters in future.