Studies on the correlation between physicochemical properties of fly ash and its sorption of gas-phase arsenic

This study investigated the adsorption behaviors of gas-phase arsenic on four kinds of fly ashes through using a fixed-bed reactor, and analyzed the correlation between sorption of gas-phase arsenic and physicochemical properties of fly ashes at different adsorption temperatures. The results showed that different fly ashes all had an adsorption effect on arsenic. The carbon content and specific surface area had a promoting effect on arsenic adsorption at the low temperature of 400℃, but there was no obvious correlation between arsenic adsorption and the contents of Fe₂O₃ and CaO. However, it was exactly the opposite at the high temperature of 600℃. So the correlation between physicochemical properties of fly ash and its sorption of arsenic was proved to vary with temperature. It was further revealed that the physical adsorption predominated in temperatures ranging between 200℃ and 400℃, while the chemical adsorption predominated at further higher temperatures. The optimal temperature to maintain a high arsenic capture efficiency should be around 600℃.