Removal of Vapor-Phase Elemental Mercury by Novel Chemically Promoted Noncarbon Sorbents

Adsorption experiments of vapor-phase elemental mercury were carried out using bromine and iodine modified Kaolin, Zeolite, Bentonite and Chitosan in a laboratory-scale fixed-bed reactor. VM3000 online mercury analyzer was applied to detect the inlet and outlet Hg⁰ concentrations. The characterizations of the sorbents were analyzed using Fourier transform infra-red spectroscopy. The results indicated the iodine was found in the inlayer of Bentonite, and the chemical reactions of iodine and sulfate ion with the amide of Chitosan were occurred. Fixed-bed absorber tests showed that compared to Kaolin and Zeolite, the modified Bentonite exhibited excellent mercury capture because of its unique structure. Mercury removal efficiency of Chitosan sorbent could be promoted from 50% to 100% when added appropriate amount of H₂SO₄. The iodine-modified sorbents demonstrated higher mercury capture efficiency than that of bromine-modified sorbents. Moisture presence can decrease the Bentonite´s capacity for mercury uptake, while that of chitosan sorbents exhibited opposite tendency due to their unique physicochemical properties.