Electrospun metal oxide-TiO2 nanofibers for elemental mercury removal from flue gas

Nanofibers prepared by an electrospinning method were used to remove elemental mercury (Hg-0) from simulated coal combustion flue gas. The nanofibers composed of different metal oxides (MOx) including CuO, In2O3, V2O5, WO3 and Ag2O supported on TiO2 have been characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersing X-ray (EDX) and UV-vis spectra. The average diameters of these nanofibers were about 200 nm. Compared to pure TiO2, the UV-vis absorption intensity for MOx-TiO2 increased significantly and the absorption bandwidth also expanded, especially for Ag2O-TiO2 and V2O5-TiO2. Hg-0 oxidation efficiencies over the MOx-TiO2 nanofibers were tested under dark, visible light (vis) irradiation and UV irradiation, respectively. The results showed that WO3 doped TiO2 exhibited the highest Hg-0 removal efficiency of 100% under UV irradiation. Doping V2O5 into TiO2 enhanced Hg-0 removal efficiency greatly from 6% to 63% under visible light irradiation. Ag2O doped TiO2 showed a steady Hg-0 removal efficiency of around 95% without any light due to the formation of silver amalgam. An extended experiment with 8 Hg-0 removal cycles showed that the MOx-TiO2 nanofibers were stable for removing Hg-0 from flue gas. Factors responsible for the enhanced photocatalytic activities of the MOx-TiO2 nanofibers were also discussed. (C) 2012 Elsevier B.V. All rights reserved.