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

Abstract

Nanofibers prepared by an electrospinning method were used to remove elemental mercury (Hg0) 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 200nm. 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. Hg0 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 Hg0 removal efficiency of 100% under UV irradiation. Doping V2O5 into TiO2 enhanced Hg0 removal efficiency greatly from 6% to 63% under visible light irradiation. Ag2O doped TiO2 showed a steady Hg0 removal efficiency of around 95% without any light due to the formation of silver amalgam. An extended experiment with 8 Hg0 removal cycles showed that the MOx–TiO2 nanofibers were stable for removing Hg0 from flue gas. Factors responsible for the enhanced photocatalytic activities of the MOx–TiO2 nanofibers were also discussed.