Effects of frequency and initial concentration of methylene blue on rate constants of ultrasonic degradation

Abstract

Ultrasound has been found to be an attractive advanced technology for the degradation of hazardous organic compounds in water. The ultrasonic degradation of dyes has been investigated by many researches, but the effects of ultrasonic frequency on degradation rate were not investigated quantitatively. In our previous study, we proposed a simple model for estimating the apparent degradation rate constant of methylene blue based on ultrasonic power and the SEKI value in the range of frequency between 20 kHz and 500 kHz. However, we have not investigated the ultrasonic degradation of methylene blue in high frequency region around 1 MHz. The effects of initial concentration of methylene blue have not been investigated yet, either. In this study, the degradation process using methylene blue as model hazardous organic compounds by ultrasonic irradiation was investigated. The ultrasonic frequency was operated in the range from 20 kHz to 1.6 MHz, and the initial concentration of methylene blue was in the range from 0.005 to 0.04 mM. Our proposed model can apply to this study which extended the frequency range. The effects of initial concentration can also be estimated in the range of 0.01 to 0.04 mM using this model. © 2013 Acoustical Society of America.