A reaction mechanism has been validated for the photochemical generation of hydroxyl radicals by ultraviolet or visible irradiation of oxalato iron(III) complexes (ferrioxalate) in the presence of hydrogen peroxide and 2-propanol as a modelsubstrate. A kinetic simulation program incorporating the set of reactions was written to predict the behavior of this photochemical system. The program calculates the quantum yield of oxidation of 2-propanol used as a hydroxyl radical scavenger. Thescavengers oxidation product, 2-propanone, was analyzed by gas chromatography after controlled exposure of the solution to a calibrated light source. The theoretical quantum yields of 2-propanol oxidation, ~RH, agreed reasonably well with experimentallydetermined ~RH values under a variety of initial reaction conditions. The value ofΦ{sub}(RH), which under appropriate conditions is directly proportional to the quantum yield for the generation of hydroxyl radicals, Φ{sub}(RH), was considerably greaterthan unity in most cases (oftenΦ{sub}(RH)= 3.0-40), indicative of a chain mechanism involving iron cycling between the II and III oxidation states
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