Adsorption performance of semi-coke modified by KMnO₄ solution for gas-phase Hg⁰ in flue gas

In an attempt to develop a novel and more effective sorbent with low-cost for the removal of gas-phase Hg⁰ from flue gas, the adsorption performance of semi-coke and KMnO₄ solution-modified semi-coke for gas-phase Hg⁰ was investigated with a bench-scale fixed-bed reactor system. The experimental results suggest that the adsorption performance of semi-coke is good at low temperature but weak at higher temperature. The semi-cokes impregnated by KMnO₄ solution have excellent adsorption performance for gas-phase Hg⁰ at 140 ℃, and can be further enhanced by heating the impregnated samples at 250 ℃. The BET analysis shows that the semi-coke has rich micro-pores but become poor after modification. The XPS results indicates that the adsorbed mercury on the surface of the modified semi-coke samples mainly exists in oxidation state (Hg²⁺) and these compounds (KMnO₄, K₂MnO₄ and MnO₂ ) play a key role in the oxidation reaction of gas-phase Hg⁰.