Removal of Hg0 from a simulated flue gas by photocatalytic oxidation on Fe and Ce co-doped TiO2 under low temperature

Fe and Ce co-doped TiO2 composites were synthesized by a sol-gel method and subsequently employed as a photocatalyst to oxidize elemental mercury (Hg-0) from a zinc smelting flue gas. Hg-0 photo-oxidation were conducted under UV irradiation (253.7 nm). A series of influence factors have been investigated: calcination temperature, pH of the sol, amounts of Fe2O3 and CeO2, reaction temperature and flue gas components. Hg-0 photo-oxidation efficiency as high as 95% at 30 degrees C was obtained over Fe5Ce5Ti synthesized at the sol pH = 6 as a result of the optimum optical absorption properties and maximum specific surface area (109.543m(2)/g) of this material. Besides, O-2 and SO2 contributed to favor photo-oxidation of Hg-0 while NO exhibited inhibition. Based on UV-vis diffuse reflectance spectroscopy (DRS) and photoluminescence (PL) revealed a red-shifted absorption edge for Fe5Ce5Ti, which prevented the recombination of the photogenerated charge carriers and decreased the band gap width (2.34 eV). In addition, X-ray photoelectron spectroscopy (XPS) indicated that HgO was the main species of the mercury on the used Fe5Ce5Ti sample. This species was generated by photo-oxidation of Hg-0 with O-beta, % center dot O2- and h(+).