Electrochemical degradation of paracetamol from water by catalytic action of Fe2+, Cu2+, and UVA light on electrogenerated hydrogen peroxide

Acidic aqueous solutions of the drug paracetamol have been degraded by anodic oxidation and indirect electro-oxidation methods using an undivided electrolytic cell with a Pt anode and an O-2-diffusion cathode for H2O2 electrogeneration. Anodic oxidation yields low mineralization due to the limited production of oxidant hydroxyl radical ((OH)-O-.) from water oxidation at Pt. The presence of Cu2+ as catalyst, with and without (ultraviolet A, UVA) irradiation, slightly enhances the degradation process. In electro-Fenton, much more (OH)-O-. is produced from Fenton's reaction between added Fe2+ and electrogenerated H2O2, but stable Fe3+ complexes are formed. These species are partially photodecomposed in photoelectro-Fenton under UVA irradiation. The use of Fe2+ and Cu2+ yields fast decontamination because Cu2+ complexes are destroyed. Total mineralization of paracetamol is achieved when Fe2+, Cu2+, and UVA light are combined. The influence of current, pH, and drug concentration upon the efficiency of catalyzed methods is studied. Hydroquinone, p-benzoquinone, and carboxylic acids, such as ketomalonic, maleic, fumaric, oxalic, and oxamic, are detected as intermediates. The positive synergetic effect of all catalysts is explained by the oxidation of Cu2+-oxalato and Cu2+-oxamato complexes with (OH)-O-., along with the photodecarboxylation of Fe3+-oxalato and Fe3+-oxamato complexes by UVA light. NH4+ and NO3- are released during drug mineralization. (c) 2005 The Electrochemical Society.