Abstract: The combination of ESR spectroscopy and spin trapping technique was used to detect free radical intermediates formed upon irradiation of ZnO powders dispersed in a mixture of water and alcohol (methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, and 2-butanol) The ESR signals for the 5,5-dimethyl-l-pyrroline-N-oxide (DMPO) adducts were observed. Hydro-xyalkyl adducts were identified Experiments performed with ZnO aqueous dispersions containing various amounts of alcohol suggest that alcohol should be very sensitive toward oxidation by the photogenerated holes. Hydroxyl radical formation seems to be the first step in the pho-tooxidation process of water. Alcohols can be oxidized by the radical, leading to the formation of hydroxyalkyl radicals.

Key words: zinc oxide, photoreaction, hydroxyalkyl radical, spin trapping