Photocatalytic oxidation of oxalic acid by oxygen and ozone in aqueous solution

Experimental study of mineralization of oxalic acid Н2С2О4 and some other oxidation-resistant organic compounds in an aqueous solution under the action of oxygen, ozone, and ultraviolet radiation is performed. It is found that in acidic solutions Н2С2О4 is not oxidized under the action of ozone or UV-irradiation in the presence of oxygen; under simultaneous action of O3 + UV, oxidation with low rate is observed. The possibility of photocatalysis of mineralization process by ions Mn2+, MnO4–, Fe3+, Со2+, BrO3–, or IO3– is studied. Fe3+ ions are the most effective photocatalyst as there is a rather fast oxidation of oxalic acid to CO2 in their presence and under UV-irradiation both under the action of O3 and O2. The conditions of maximum ozone conversion at oxalic acid photomineralization are found. The possibility of oxidative destruction of more oxidation-resistant substrate - acetic acid - at ozonation and UV-irradiation of solutions with Fe(III) and Н2С2О4 additives is shown.