Photolysis of Aqueous H_2O_2: Quantum Yield and Applications for Polychromatic UV Actinometry in Photoreactors

摘要

Methanol is used to measure the yield of ~·OH radicals produced in the photolysis of H_2O_2 in aqueous solutions. The UV photolysis of H_2O_2 generates ~·OH radicals, which in the presence of methanol, oxygen, and phosphate buffer form formaldehyde, namely, Φ(HCHO) = Φ(~·OH). The quantum yield of ~·OH has been redetermined in view of literature inconsistencies resulting in Φ(~·OH) = 1.11 ± 0.07 in the excitation range of 205-280 nm. The constancy of Φ(~·OH) and the ease and sensitivity of the formaldehyde product analysis makes the H_2O_2/CH_3OH system suitable for polychromatic UV actinometry.