title: Comparison of ultrasonic degradation rates constants of methylene blue at 22.8 kHz, 127 kHz, and 490 kHz.
abstract: Techniques such as solvent extraction, incineration, chemical dehalogenation, and biodegradation have been investigated for the degradation of hazardous organic compounds. We found ultrasound to be an attractive technology for the degradation of hazardous organic compounds in water. However, the effects of ultrasonic frequency on degradation rate constants were not investigated quantitatively. In this study, the degradation process of a model for hazardous organic compound methylene blue was investigated using ultrasonic irradiation. The study focused on the effects of ultrasonic frequency and ultrasonic power on the degradation rate constant. The apparent degradation rate constants were estimated based on time dependence of methylene blue concentration assuming pseudo-first-order kinetics for the decomposition. A linear relationship between the apparent degradation rate constant and ultrasonic power was identified. In addition, the apparent degradation rate constants at frequencies of 127 and 490 kHz were much larger than those at 22.8 kHz. A relationship between the apparent degradation rate constant and the sonochemical efficiency value (SE value) was also found. Based on these results, a simple model for estimating the apparent degradation rate constant of methylene blue based on the ultrasonic power and the SE value is proposed in this study.
authors.affiliation: Department of Industrial Chemistry, Faculty of Engineering, Tokyo University of Science, Kagurazaka 1-3, Shinjuku-ku, Tokyo 162-8601, Japan. dkobayashi@ci.kagu.tus.ac.jp
authors.forename: Daisuke
authors.initials: D
authors.lastname: Kobayashi
authors.forename: Chiemi
authors.initials: C
authors.lastname: Honma
authors.forename: Atsushi
authors.initials: A
authors.lastname: Suzuki
authors.forename: Tomoki
authors.initials: T
authors.lastname: Takahashi
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Matsumoto
authors.forename: Chiaki
authors.initials: C
authors.lastname: Kuroda
authors.forename: Katsuto
authors.initials: K
authors.lastname: Otake
authors.forename: Atsushi
authors.initials: A
authors.lastname: Shono
mesh_terms: D008751:Methylene Blue / Q000737:chemistry*; D013010:Sonication
chemical_list: D008751:Methylene Blue