Gas-phase destruction of H2S using TiO2/UV-VIS

Photocatalytic destruction of H2S using TiO2/UV-VIS was conducted in the gas-phase. This process showed high efficiency, reaching degradation yields of 99% at concentration ranges of 33 to 855 ppmv. Oxygen was shown to be necessary for the photodestruction of H2S. Conversion rates were small in experiments conducted under nitrogen atmosphere (17%) compared with experiments in the presence of oxygen (99%). The photocatalytic activity of TiO2 showed that at 217 ppmv, there was no loss of the activity over extended operation periods. Deactivation of the catalyst was observed only when working at higher H2S concentrations (such as 600 ppmv), and is assumed to be caused by the adsorption of the byproducts produced onto the catalyst surface. The main product in the photocatalytic destruction of H2S in gasphase detected by FTIR and for turbidimetric analysis was sulfate ions. A mass balance showed that H2S is oxidized to SO4-2 (95% of SO4-2 were easily recovered from the catalyst surface), and that only 0.02% of this ion was detected at the reactor effluent. Experiments carried out using the photocatalytic process to minimize noxious emission of H2S stripped from a raw sewage sample showed that this process is viable for the elimination of odor in wastewater treatment plants. (C) 1998 Elsevier Science S.A.