Sonolysis of an oxalic acid solution under xenon lamp irradiation

The photosonolysis of oxalic acid was carried out in an Ar atmosphere. The detectable products of sonolysis were CO2, CO, H2, and H2O2. The yield of CO2 was higher than that for the sum of sonolysis and photolysis reactions. Namely, a synergistic effect was observed during simultaneous irradiations of 200 kHz ultrasound and Xe lamp. The degradation of oxalic acid was promoted by active species such as H2O2 produced from water by sonolysis. An oxalic acid–H2O2 complex is likely to be present in the solution, but could not be detected. The effects of not only the photo-irradiation but also the thermal or incident energy during Xe lamp illumination were also considered.