Effects of experimental parameters on Hg0 removal over magnetic AgI-BiOI/CoFe2O4 photocatalysts using wet process

Abstract

A novel magnetic AgI-BiOI/CoFe2O4 hybrid composites were prepared via a solvothermal and subsequent coprecipitation method, and utilized to remove Hg0 from coal-fired flue gas under fluorescent light irradiation. The experimental parameters and main products presented in solution after reaction were investigated in detail. The experimental results showed that the AgI-BiOI/CoFe2O4 composites showing a poor thermal stability would transform into other compounds when the calcinated temperature was above 400°C. With the increases of photocatalyst dosage, reaction solution pH, temperature of reaction solution in reactor and O2 concentration, the Hg0 removal efficiencies were first increased and then unchanged or decreased. The presences of inorganic anions such as CO2−3 and SO2−4 in solution exhibited some inhibitory effects on Hg0 removal. Furthermore, the presence of SO2 had a dramatic inhibition on Hg0 removal, while the inhibitory effect of NO on Hg0 removal was relatively small. SO2−4, NO−3 and Hg2+ species were the final oxidation products of SO2, NO and Hg0 by reactive species.