The 254-nm photodecomposition kinetics of aqueous oxalate species (C2O42-, HC2O4-, and H2C2O4) were investigated using low-pressure mercury lamps in a commercial photoreactor.  Experiments were conducted using a range of pH values to systematically adjust the oxalate speciation among its three forms.  The total oxalate concentration ([ox]tot = [C2O42-] + [HC2O4-] + [H2C2O4])was monitored using a calibrated HPLC method on periodic aliquots of the irradiated solutions.  Quantum yields for the 254-nm photodecomposition of each species (oxalate, bioxalate, and oxalic acid) were determined by applying a kinetic model to the laboratory results.  As part of this study, the molar absorptivity for each aqueous species was determined from 200 to 270 nm using UV-Vis spectroscopy.  Estimated values for the quantum yield and a proposed mechanism for each oxalate species are reported and discussed.

UV-photochemistry of aqueous oxalate species

245th National Meeting (2013)

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