Hydrogen peroxide mediated photodegradation of phenol as studied by a flash photolysis/HPLC technique

The technique of flash photolysis followed by high-performance liquid chromatography has been applied to the study of the photodegradation of phenol (I) in the presence of hydrogen peroxide. Progress of the reaction of I (0.1 mM) in undegassed aqueous solution ([H2O2]/[I] = 200/l) was observed by using multiple flashes (16 J). Analysis after a single flash indicated that catechol and hydroquinone were the primary products of the reaction. The reaction was found to be independent of pH in the range 7.0-9.0, but the yield of degradation decreased at pH > 9.0 and at pH < 7.0. The effects of the hydrogen peroxide concentration and flash energy on the chemical yield of the pollutant degradation, and product formation, were investigated as well. The mechanism of the reaction is discussed. A possibility of the application of flashlamps as powerful sources of the UV irradiation in industrial reactors for wastewater treatment is suggested.