Kinetics analysis for development of a rate constant estimation model for ultrasonic degradation reaction of methylene blue

Daisuke Kobayashi; Chiemi Honma; Hideyuki Matsumoto; Tomoki Takahashi; Chiaki Kuroda; Katsuto Otake; Atsushi Shono

doi:10.1016/j.ultsonch.2013.12.022

Kinetics analysis for development of a rate constant estimation model for ultrasonic degradation reaction of methylene blue

Ultrason Sonochem. 2014 Jul;21(4):1489-95. doi: 10.1016/j.ultsonch.2013.12.022. Epub 2014 Jan 3.

Authors

Daisuke Kobayashi¹, Chiemi Honma², Hideyuki Matsumoto³, Tomoki Takahashi⁴, Chiaki Kuroda³, Katsuto Otake⁴, Atsushi Shono⁴

Affiliations

¹ Department of Industrial Chemistry, Faculty of Engineering, Tokyo University of Science, Kagurazaka 1-3, Shinjuku-ku, Tokyo 162-8601, Japan. Electronic address: dkobayashi@ci.kagu.tus.ac.jp.
² Department of Chemical Science and Technology, Graduate School of Chemical Science and Technology, Tokyo University of Science, Kagurazaka 1-3, Shinjuku-ku, Tokyo 162-8601, Japan.
³ Department of Chemical Engineering, Graduate School of Science and Engineering, Tokyo Institute of Technology, O-okayama 2-12-1, Meguro-ku, Tokyo 152-8550, Japan.
⁴ Department of Industrial Chemistry, Faculty of Engineering, Tokyo University of Science, Kagurazaka 1-3, Shinjuku-ku, Tokyo 162-8601, Japan.

PMID: 24439912
DOI: 10.1016/j.ultsonch.2013.12.022

Abstract

Ultrasound has been used as an advanced oxidation method for wastewater treatment. Sonochemical degradation of organic compounds in aqueous solution occurs by pyrolysis and/or reaction with hydroxyl radicals. Moreover, kinetics of sonochemical degradation has been proposed. However, the effect of ultrasonic frequency on degradation rate has not been investigated. In our previous study, a simple model for estimating the apparent degradation rate of methylene blue was proposed. In this study, sonochemical degradation of methylene blue was performed at various frequencies. Apparent degradation rate constant was evaluated assuming that sonochemical degradation of methylene blue was a first-order reaction. Specifically, we focused on effects of ultrasonic frequency and power on rate constant, and the applicability of our proposed model was demonstrated. Using this approach, maximum sonochemical degradation rate was observed at 490 kHz, which agrees with a previous investigation into the effect of frequency on the sonochemical efficiency value evaluated by KI oxidation dosimetry. Degradation rate increased with ultrasonic power at every frequency. It was also observed that threshold power must be reached for the degradation reaction to progress. The initial methylene blue concentration and the apparent degradation rate constant have a relation of an inverse proportion. Our proposed model for estimating the apparent degradation rate constant using ultrasonic power and sonochemical efficiency value can apply to this study which extended the frequency and initial concentration range.

Keywords: Degradation rate constant; Frequency; Initial concentration; Kinetic analysis; Methylene blue; Sonochemical efficiency value.