Magnetic biochar has been proven to be an efficient adsorbent for the removal of elemental mercury(Hg0).However,SO2、NO and HCl are acid components of the oxyfuel combustion flue gas,and their roles in magnetic biochar removal of Hg0 have not been determined.By simulating an experimental setup with oxyfuel combustion atmosphere,the effects of acidic gas concentration on the adsorption and oxidation efficiencies of Hg0 at different reaction temperatures,as well as the thermal regeneration cycling performance of magnetic biochar,were thoroughly investigated.The results showed that 0.4％SO2 promoted the adsorption of Hg0 by magnetic biochar with 93.5％Hg0 removal at 120 ℃,but higher concentrations of SO2(＞0.4％)produced an inhibitory effect and promoted the oxidation of a small amount of Hg0,which partially alleviated the inhibitory effect of SO2 on the adsorption of Hg0.Meanwhile,NO shows a similar pattern in oxyfuel combustion atmosphere.Gaseous HCl is an important accelerator,and the mercury removal rate in the presence of 0.02％HCl is close to 100％,which counteracts the adverse effects of flue gas components.However,the pattern of action of SO2 on Hg0 removal from magnetic biochar at high temperatures was similar to that at 120 ℃.At 350 ℃,1.6％SO2 inhibited Hg0 adsorption even more,with an adsorption efficiency of only 19.5％,which was lower than the efficiency of Hg0 oxidation,and mainly generated more oxygen-containing functional groups such as C=O;NO also showed strong inhibition at high temperatures,and the rate of mercury removal gradually decreased with increasing NO concentration,with the lowest rate dropping to about 50％.It can be seen that high temperature and high concentration of SO2 and NO are unfavorable for magnetic biochar mercury removal.In addition,the magnetic biochar deactivated by mercury removal has excellent thermal regeneration stability,with about 80％mercury removal efficiency after thermal regeneration at 450 ℃ and cycling four times.
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