Mechanochemical Semidry Modification of Fly Ash for Mercury Removal

ABSTRACT Fly ash is a potential mercury adsorbent due to its well‐developed pores, but its poor physical and chemical properties limit the efficiency of mercury adsorption so that it needs to improve its adsorption capacity. The mechanochemical semidry modification of fly ash prepared by an all‐round planetary ball mill and the effects of KClO 3 , S, KCl, and K 2 SO 4 taken as modifiers on mercury removal were investigated by experiment and characterization. The results indicate that the mechanochemical semidry samples demonstrate a larger specific surface area, a more developed pore structure. The mercury removal efficiencies affected by the modifiers rank in descending order as follows: KClO 3 > S > KCl > K 2 SO 4 . Notably, KClO 3 and S are more effective than others, achieving a mercury removal efficiency of 87% and 63%. The mechanism of mercury adsorption of fly ash modified by KClO 3 and S is elucidated. The mercury removal is predominantly governed by oxidation, accounting for more than 90%, with weak adsorption. The modified fly ash can be an efficient and economic adsorbent for flue gas mercury removal in coal‐fired flue gas.