Host: The Japan Society of Mechanical Engineers
Name : Mechanical Engineering Congress,Japan
Date : September 11, 2016 - September 14, 2016
Microbubbles generated by a pressurized dissolution method and ultrasonic waves are applied to decomposition of organic compounds. Though there has been some reports on such research so far, the relation between microbubbles and ultrasonic waves has not been discussed in detail. In the present study, first, the effects of microbubbles or ultrasonic waves on the decomposition of methylene blue is examined from the comparison of decomposition rates obtained from the experiments under some conditions; at rest, water flow, microbubbles alone, ultrasonic waves alone, and the combination of microbubbles and ultrasonic waves. Next, the influence of the frequency of ultrasonic waves on the decomposition of methylene blue is investigated. A bubble has a natural frequency according to the bubble dynamics, and it oscillates explosively when it is exposed to the ultrasonic wave with the natural frequency. The frequencies 20 kHz, 70 kHz, 100 kHz, 140 kHz, 200 kHz, 250 kHz, and 330 kHz are used in the present experiment. As a result, the combination of microbubbles and ultrasonic could decompose the methylene blue most rapidly. In particular, among the above frequencies, the methylene blue could be hardly decomposed in the case of 70 kHz and 330 kHz, and it could be decomposed in the case of 200 kHz most rapidly. The mean bubble radius measured by laser diffraction-scattering type particle size distribution measuring device is 54 μm and its natural frequency is 123 kHz. Though the discrepancy is small, its cause could not be clearly specified.
