Effect of Gas Composition on Pulsed Corona Discharge Characteristics and Hg0 Removal Performance

Plasma technology effectively removes Hg0 by oxidizing it via highly reactive species, offering an efficient and rapid approach for mercury emission control. In this work, we investigated the mechanism of Hg0(g) removal by pulsed corona discharge non-thermal plasma in pure N2 and N2(80%)–O2(20%) mixtures (or simulated air). Experimental and simulation methods were employed to thoroughly investigate corona discharge electrical characteristics and optical properties, and Hg0 removal efficiency, while plasma processes and particle evolution mechanisms were analyzed. Hg0 was effectively removed in pure N₂ under pulsed corona discharge, achieving 79% efficiency. Despite discharge instability in simulated air due to oxygen’s electronegativity, its strong oxidizing ability enabled nearly complete Hg0 oxidation via enhanced plasma chemistry. Mechanistic analysis indicates that the pulse corona discharge generates abundant high-energy electrons and reactive oxygen species, which play a critical role in the effective removal of Hg0. The reactive oxygen species in the N2-O2 plasma is suggested to be the key issue for improving the efficiency of Hg0 removal. The higher electron temperature in simulated air helps provide sufficient reactive conditions for Hg0 removal. This research provides valuable insights into the development of more effective non-thermal plasma systems for Hg0 control and enhances the theoretical foundation of plasma technology for Hg0 removal.