The photooxidation kinetics of aqueous oxalate species (H2C2O4, HC2O4, C2O42-) by the hydroxyl radical (OH) was investigated in the presence and absence of oxygen. Aqueous solutions containing oxalate and hydrogen peroxide (used as the precursor of OH radicals) were irradiated in a commercial photoreactor. The pH was lowered to 0.4- 0.7, at which the oxalic acid form (H2C2O4) predominates. The concentrations of oxalic acid, hydrogen peroxide, and formic acid were determined by spectrophotometric methods throughout the photolysis. The data were compared to a kinetics model to find an overall rate constant for the reaction, and to determine the potential role of oxygen in the mechanism. The observed formation of formic acid provided additional mechanistic insight.

Kinetics and mechanism for the reaction of oxalic acid with the hydroxyl radical

247th National Meeting (2014)

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