Influence of carbon-functional groups with less hydrophilicity on a TiO2 photocatalyst for removing low-level elemental mercury

A carbon-containing titanium dioxide (C-TiO2) photocatalyst was prepared via ethanol impregnation using commercial Ishihara ST-01 TiO2 powder as the precursor. Scanning Electron Microscopy and X-ray Diffractometry results indicated that raw ST-01 and C-TiO2 had similarly globular shapes and presented in anatase phase. N2 adsorption isotherms suggested that carbon impregnated on the TiO2 surface could slightly reduce the total surface area and pore volume. X-ray Photoelectron Spectroscopy and Fourier Transform Infrared Spectroscopy examinations further supported the formation of various C-functional groups on the C-TiO2 surface. Removal of low-concentration Hg0 by raw and C-TiO2 was enhanced with increasing O2 concentration. Furthermore, because the existence of C-functional groups on the C-TiO2 surface, the photoinduced hydrophilicity resulted from light irradiation appears to decrease, causing less adsorption competition from H2O for Hg0 adsorption at higher temperature. The reemission of adsorbed Hg species could thus be significantly decreased by carbon impregnation.