Effect of dimethyl sulfoxide addition on ultrasonic degradation of methylene blue

The ultrasonic degradation of methylene blue was carried out in the absence and presence of dimethyl sulfoxide (DMSO) as a radical scavenger for various frequencies, and the effects of DMSO addition on the degradation rate constant estimated by assuming first-order kinetics were investigated. The degradation reaction rate decreased with DMSO addition, and hydroxyl radicals were observed to play important roles in the degradation of methylene blue. However, the degradation reaction did not stop with DMSO addition, and the degradation rate constant in the presence of DMSO was not affected by ultrasonic frequency.