Synergistically achieving particulate matter reduction and production performance optimization for zinc electrolysis by ultrasonication coupling anode-coated MnO2

Abstract

Abating particulate matter (PM) from electrolysis processes is significant because this PM poses occupational threats to workers and has a negative impact on air quality. However, it remains a challenge to synergize the reduction of PM production and the improvement of electrolysis performance. This study developed a green method, termed as the coupling of ultrasonication and pre-coating MnO₂ anode treatment (UMT). The effects on PM generation rate and electrolysis performance indicators were estimated using the bench-scale zinc electrolysis device, and the synergistic mechanism of UMT was expanded from the perspective of electrochemical reactions and bubble characteristics using analysis of reaction products, camera technique, and PM generation prediction models. The results showed UMT not only overcame the degradation of deposited zinc quality caused by the ultrasonication treatment but also solved the increased PM generation by the pre-coating MnO₂ film treatment. The UMT simultaneously reduced PM (33.9 %-57.5 %), decreased zinc impurity content by (11.2 %-54.3 %), improved current efficiency of zinc deposition (0.19 %-1.71 %), and conserved electrolysis energy (0.27 %-1.01 %). The optimal performance of UMT occurred at 80 kHz. The UMT suppressed the gas evolution reactions and prematurely bursting bubbles, in favor of reducing the number and size of bubbles, to reduce PM generation. Meanwhile, the UMT improved the electrolysis performance by inhibiting the corrosion of lead-based anodes, promoting the mass transfer rate of Zn²⁺, providing more active surfaces, and decreasing the overpotential of reactions. The findings may provide references for the green development of the metal electrolysis industry.