Application of plasma technology in Hg0 removal from flue gas: Recent advances and future perspectives

Hg0 from combustion flue gas is a highly toxic substance, which is harmful for the environment, device safety and human health. Economically effective control measures are urgently needed to reduce emission of Hg0 from combustion flue gas. Plasma technology can remove Hg0 from combustion flue gas by inducing highly active species, which has the advantages of simple and environmentally friendly process. However, Hg0 removal using plasma technology has the disadvantages of big energy consumption, poor selectivity and low free radical utilization, hindering its development and application. Compared to plasma removal technology, plasma coupling catalyst/adsorbent removal technology exhibits superior development prospects due to obvious synergistic effect between plasma and catalyst/adsorbent, which can improve these shortcomings mentioned above in the single plasma removal technology. The Hg0 removal efficiency of plasma coupling catalyst/adsorbent technology was at least 11.5% higher than that of plasma removal technology alone. Besides, plasma technology is also widely used for modifying catalysts/adsorbents to remove gaseous Hg0 via generating various highly active functional groups and sites on the surface of catalysts/adsorbents, showing considerable development potential due to its clean and simple process. Compared with the original samples, the samples modified by plasma technology can achieve a Hg0 removal efficiency improvement of at least 22.4%. This paper systematically reviews gaseous Hg0 removal using plasma technology, plasma coupling catalyst/adsorbent technology and plasma-modified catalyst/ adsorbent technology, which can provide valuable guidance for developing more economically effective plasmabased Hg0 from combustion flue gas removal technologies.