title: Mercury removal from coal combustion flue gas by modified fly ash.
abstract: Fly ash is a potential alternative to activated carbon for mercury adsorption. The effects of physicochemical properties on the mercury adsorption performance of three fly ash samples were investigated. X-ray fluorescence spectroscopy, X-ray photoelectron spectroscopy, and other methods were used to characterize the samples. Results indicate that mercury adsorption on fly ash is primarily physisorption and chemisorption. High specific surface areas and small pore diameters are beneficial to efficient mercury removal. Incompletely burned carbon is also an important factor for the improvement of mercury removal efficiency, in particular. The C-M bond, which is formed by the reaction of C and Ti, Si and other elements, may improve mercury oxidation. The samples modified with CuBr2, CuCl2 and FeCl3 showed excellent performance for Hg removal, because the chlorine in metal chlorides acts as an oxidant that promotes the conversion of elemental mercury (Hg0) into its oxidized form (Hg2+). Cu2+ and Fe3+ can also promote Hg0 oxidation as catalysts. HCl and O2 promote the adsorption of Hg by modified fly ash, whereas SO2 inhibits the Hg adsorption because of competitive adsorption for active sites. Fly ash samples modified with CuBr2, CuCl2 and FeCl3 are therefore promising materials for controlling mercury emissions.
authors.affiliation: Research Center for Process Pollution Control, National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China. wqxu@home.ipe.ac.cn
authors.forename: Wenqing
authors.initials: W
authors.lastname: Xu
authors.forename: Hairui
authors.initials: H
authors.lastname: Wang
authors.forename: Tingyu
authors.initials: T
authors.lastname: Zhu
authors.forename: Junyan
authors.initials: J
authors.lastname: Kuang
authors.forename: Pengfei
authors.initials: P
authors.lastname: Jing
mesh_terms: D000397:Air Pollution / Q000517:prevention & control; D003031:Coal; D060729:Coal Ash / Q000737:chemistry*; D008628:Mercury / Q000302:isolation & purification*; D013052:Spectrometry, X-Ray Emission; D013458:Sulfur Dioxide / Q000737:chemistry
chemical_list: D003031:Coal; D060729:Coal Ash; D013458:Sulfur Dioxide; D008628:Mercury