Research progress on elemental mercury (Hg) removal in flue gas using non-thermal plasma technology.

Elemental mercury (Hg) removal is a crucial target for mercury pollution control in flue gas. This article focuses on Hg removal in flue gas using corona discharge (CD) and dielectric barrier discharge (DBD) technologies, and provides a mechanistic perspective on the development and influencing factors of non-thermal plasma (NTP) technology for Hg removal. The influence factors include reactor configurations, power supplies, energy density, residence time, oxidation methods, gas composition, and the synergy between NTP and catalysis/adsorption, etc. This study reveals that the use of a pulsating electrical power supply significantly increases electron densities in both CD and DBD systems, thereby ensuring high energy efficiency and economic viability. Cl proves to be more effective than HCl as a chlorine source for Hg removal. NO significantly reduces Hg oxidation efficiency, while the effects of SO and HO remain unclear. Energy density distribution is closely related to plasma devices, power supplies, and overall reactor configurations. Direct oxidation proves to be more effective than indirect oxidation for Hg removal. The combination of NTP with adsorption/catalysis technologies shows significantly better Hg removal efficiency compared to using NTP alone. This study can provide theoretical support for enhancing Hg removal mechanisms and optimizing process control parameters in industrial applications of NTP technology.