Adsorption of elemental mercury in flue gas using biomass porous carbons modified by microwave/hydrogen peroxide

Abstract

Abstract In order to enhance the mercury adsorption capacity of bio-char and reduce the potential environmental damage caused by modification methods, a clean modification method combining microwave activation and H2O2 impregnation of bio-char was proposed in this paper. The effects of hydrogen peroxide concentration, reaction temperature and flue gas components (NO/O2/SO2/H2O) on Hg0 removal efficiency of the modified samples were studied. The physicochemical properties of the biomass porous carbons were analyzed by various characterization methods (i.e. BET, SEM, FTIR, XPS). The results show that the biomass porous carbons, WSW10 and RSW10, exhibit the best Hg0 adsorption performance at 130\xa0℃. Microwave activation and hydrogen peroxide modification can increase the specific surface area to improve the pore structure of biomass porous carbons. The number of surface functional groups of biomass porous carbons can be increased by the H2O2 impregnation, which can improve the Hg0 removal performance of biomass porous carbons. O2 and NO contribute to the removal of Hg0. With the increase of SO2 or H2O concentration, the Hg0 removal efficiency decreases. The results of kinetic simulation show that the pseudo-second-order model can well fit the mercury adsorption process of the modified biomass porous carbons, and chemisorption occurs on the surface of the adsorbent. The C-O functional groups and chemically adsorbed oxygen play an important role in the Hg0 removal.