Ultrasonication to reduce particulate matter generated from bursting bubbles: A case study on zinc electrolysis

Particulate matters (PM) generated from bursting bubbles during electrolysis are hazardous and undesirable. Cleaner production technologies to reduce these PM by controlling bubble characteristics need to be explored. This study applied an ultrasonication method to reduce PM generated from zinc electrolysis. The results showed that the reduction efficiencies for total suspended particulates increased with the increase in ultrasonic power. The reduction mechanism was also investigated from the perspective of behavior of the bubble. The results showed that the number and size of microbubbles were both inversely related to the ultrasonic power, while positively related to the total mass of PM. Ultrasonication reduced PM by decreasing the number and size of microbubbles in two steps: i) during gas generation, ultrasonication inhibited anodic oxygen evolution and cathodic hydrogen evolution to reduce the gas amount; ii) after the formation of microbubbles, the mechanical effects of ultrasonication probably prematurely detach the microbubbles on electrode and directly burst microbubbles in electrolyte. Moreover, ultrasonication was also beneficial for increasing the current efficiency of zinc deposition and for lowering the energy consumption. The findings provided indications for ultrasonication technology to reduce PM from electrolysis and paved the road for exploring other clean PM reduction methods. (c) 2020 Elsevier Ltd. All rights reserved.