THE PHOTOOXIDATION OF ACETIC-ACID BY OXYGEN IN THE PRESENCE OF TITANIUM-DIOXIDE AND DISSOLVED COPPER IONS

Acetic acid is oxidized by oxygen in the presence of UV light, TiO2 and dissolved copper ions being the catalysts. The reaction rate is zeroth order with respect both to acetic acid and to dissolved oxygen, and is proportional to the absorbed light intensity, with a quantum yield of 0.06. The variation in reaction rate with the concentrations of the different copper species present in the solution, i.e. free ions, Cu(CH3COO)+ and Cu(CH3COO)2, leads us to propose the second of these as the reactive species adsorbed on the TiO2 surface, the diacetato complex (or neutral salt) also being adsorbed on the TiO2 surface, but as a poison. These results extend those already obtained for formic acid and are a part of a general scheme of photo-oxidation of carboxylic acids in the presence of these catalysts.