Acoustic-Solid Interaction Mechanism of Contact-Electro-Catalysis for Organic Matter Degradation

Abstract

Contact-electro-catalysis (CEC) is a representative mechanocatalysis that utilizes the interaction of ultrasonic and dielectric particles to degrade organic matter. However, this interaction has not yet obtained a general change law. This paper proposes an acoustic-solid interaction mechanism to explain the interaction between ultrasound and dielectric particles, and explores how this interaction can enhance the degradation efficiency of methyl orange (MO) in CECs. Specifically, acoustic simulation verifies that compared with the without adding polytetrafluoroethylene (PTFE) dielectric particles, the amplitude of the positive and negative acoustic waves increased by 16.22 and 25.53 times, respectively, when PTFE is added. Meanwhile, in the absence of PTFE, the acoustic wave amplitude is lower than the cavitation threshold. This finding reveals why acoustic wave alone cannot effectively degrade organic matter without the assistance of particles. Experimental data shows that the degradation efficiency of MO has been significantly improved under the combined action of particles and ultrasonic cavitation. The pseudo-first-order rate constant and kinetic constant of MO solution degradation are 1.989 h-1 and 2.489 h-1·(g·L-1), respectively. These two values are more than 9 times higher than those without PTFE particles. This works has practical value for understanding the application of CEC in the degradation of organic pollutants.

Keywords: Contact-electro-catalysis, Acoustic-solid interaction, Ultrasonic cavitation, Dielectric particle