Iron-catalyzed photochemical oxidation of benzoic acid in the atmospheric environment: Identification of reaction products and reaction mechanism

Confirmation of the reaction products is critical for understanding and proposing the reaction mechanisms involved in the photodegradation of benzoic acid in the atmosphere. A capillary electrophoresis method was used to identify reaction products of photodegradation of benzoic acid catalyzed by dissolved iron(III) species with monochromatic light at 300 nm wavelength. The simultaneous presence of benzoic acid, iron as a catalyst, and light was necessary for the reaction to take place within a reaction time frame of 210 min. Benzoic acid had two absorption bands at wavelengths of 228 and 274 nm, respectively. Thus, direct photodegradation of benzoic acid would be difficult to proceed at 300 nm because the absorption bands of benzoic acid did not significantly overlap with the wavelength (300 nm) of the lamps.