Sonocatalytic degradation of Rhodamine B catalyzed by β-Bi2O3 particles under ultrasonic irradiation.

β-Bi2O3 particles were synthesized by a polyacrylamide sol-gel method. The sonocatalytic activity of β-Bi2O3 particles was evaluated by degrading Rhodamine B (RhB) under the ultrasonic irradiation, revealing that β-Bi2O3 particles exhibit a good sonocatalytic activity. The effects of various experimental factors including ultrasonic frequency (f), solution temperature (T), catalyst dosage (Ccatalyst) and initial RhB concentration (CRhB) on the sonocatalysis efficiency were investigated. The optimum conditions for sonocatalytic degradation of RhB are obtained to be f=60 kHz, T=40 °C, Ccatalyst=3 g L(-1), and CRhB=5 mg L(-1). The percentage degradation of RhB after sonocatalysis for 90 min is 98.7%. Detected by the photoluminescence technique that of using terephthalic acid as a probe molecule, hydroxyl radicals (OH) are found to be produced on the irradiated by β-Bi2O3 particles. Based on the experimental results, OH radicals are suggested to be the major active species which are responsible for the degradation reaction.