Acoustic cavitation at low gas pressures in PZT-based ultrasonic systems.

The generation of cavitation-free radicals through evanescent electric field and bulk-streaming was reported when micro-volumes of a liquid were subjected to 10 MHz surface acoustic waves (SAW) on a piezoelectric substrate [Rezk et al., J. Phys. Chem. Lett. 2020, 11, 4655-4661; Rezk et al., Adv. Sci. 2021, 8, 2001983]. In the current study, we have tested a similar hypothesis with PZT-based ultrasonic units (760 kHz and 2 MHz) with varying dissolved gas concentrations, by sonochemiluminescence measurement and iodide dosimetry, to correlate radical generation with dissolved gas concentrations. The dissolved gas concentration was adjusted by controlling the over-head gas pressure. Our study reveals that there is a strong correlation between sonochemical activity and dissolved gas concentration, with negligible sonochemical activity at near-vacuum conditions. We therefore conclude that radical generation is dominated by acoustic cavitation in conventional PZT-based ultrasonic reactors, regardless of the excitation frequency. Copyright © 2021 The Author(s). Published by Elsevier B.V. All rights reserved.

Citation

Joydip Mondal, Wu Li, Amgad R Rezk, Leslie Y Yeo, Rajaram Lakkaraju, Parthasarathi Ghosh, Muthupandian Ashokkumar. Acoustic cavitation at low gas pressures in PZT-based ultrasonic systems. Ultrasonics sonochemistry. 2021 May;73:105493

PMID: 33609993

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