GAS-PHASE DESTRUCTION OF H2S USING TIO2 UV-VIS/

Photocatalytic destruction of H2S using TiO2/UV-VIS was conducted in t he gas-phase. This process showed high efficiency, reaching degradatio n yields of 99% at concentration ranges of 33 to 855 ppmv. Oxygen was shown to be necessary for the photodestruction of H2S. Conversion rate s were small in experiments conducted under nitrogen atmosphere (17%) compared with experiments in the presence of oxygen (99%). The photoca talytic activity of TiO2 showed that at 217 ppmv, there was no loss of the activity over extended operation periods. Deactivation of the cat alyst was observed only when working at higher H2S concentrations (suc h as 600 ppmv), and is assumed to be caused by the adsorption of the b yproducts 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 H 2S is oxidized to SO4-2 (95% of SO4-2 were easily recovered from the c atalyst surface), and that only 0.02% of this ion was detected at the reactor effluent. Experiments carried out using the photocatalytic pro cess to minimize noxious emission of H2S stripped from a raw sewage sa mple showed that this process is viable for the elimination of odor in wastewater treatment plants. (C) 1998 Elsevier Science S.A.