Hg0 Removal by Straw Biochars Prepared with Clean Microwave/H2O2 Modification

Biochar is one of the most promising adsorbents for Hg-0 from flue gas due to renewable raw materials. Cotton straw and maize straw biochars prepared by microwave activation and H2O2 modification were used for removing Hg-0 from flue gas. Hg-0 capture efficiency and mechanism on biochars were studied. Cotton straw and maize straw biochars modified with 2 and 10% H2O2, respectively, show optimal Hg-0 removal performance exceeding that of activated carbon. Microwave activation and H2O2 impregnation greatly improve the BET surface areas of the biochars. H2O2 impregnation increases the number of O-containing functional groups, i.e., O-H and C-O, on the biochar surface, enhancing Hg-0 removal. Chemisorption dominates the Hg-0 capture on biochars.

Automated summary

Biochar, made from renewable raw materials, shows great potential in removing Hg-0 from flue gas. Cotton straw and maize straw biochars modified with H2O2 demonstrate better performance in Hg-0 removal compared to activated carbon. The combination of microwave activation and H2O2 impregnation increases the BET surface areas and oxygen-containing functional groups on biochar, enhancing Hg-0 removal through chemisorption.