The effect of dissolve gas concentration in the initial growth stage of multi cavitation bubbles Differences between vacuum degassing and ultrasound degassing

• Published in: Ultrasonics sonochemistry Vol. 15; no. 4; pp. 492 - 496
• Main Author: YANAGIDA, Hirotaka
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier 01.04.2008
• Subjects: Chemistry; Deuterium Oxide - chemistry; Deuterium Oxide - radiation effects; Exact sciences and technology; Gases - chemistry; Gases - radiation effects; General and physical chemistry; Luminescence; Physical chemistry of induced reactions (with radiations, particles and ultrasonics); Ultrasonic chemistry; Ultrasonics; Vacuum; Water - chemistry; Water; Degassing; Sonochemistry; 43.35.Vz; 43.25.Zx; Growth; Luminescence; Sonolysis; Cavitation bubble; Dissolved oxygen; Cavitation; Ultrasound; Sonochemical luminescence; Luminol; Dissolved oxygen; Cavitation; Water sonolysis
• ISSN: 1350-4177; 1873-2828
• DOI: 10.1016/j.ultsonch.2007.06.008

The sonochemical luminescence intensity from luminol was measured at a sampling rate of several kilohertz. This was noted at three different periods: first, the latent period in which no light emission occurs at all; second, the increased emission period from the start of light emission to the time when a steady state is reached; and third, the steady state period in which light emission occurs at the steady state value. When irradiated with ultrasound of different intensities, the times of the latent period and increased emission period are shorter for higher ultrasound intensities. To know how the dissolved oxygen content is involved in early-stage cavitation growth, an experiment was conducted using solutions with varying dissolved oxygen contents from 100% to 37%. For dissolved air content of 50% or less, it was found that the latent period was 30 times longer in a saturated condition. It was also found that the increased emission period was 10 times longer. However, the emission intensity in the steady state did not change at all even when the initial dissolved gas concentration of the sample was changed. From this, it was found that the reuse of collapsed bubbles takes place efficiently in the steady state. Dissolved oxygen was reduced by the use of a vacuum pump and by the degassing action of ultrasound, and it was discovered that the behavior of transient emission differed for the two ways of degassing.