Degradation of diclofenac in water by heterogeneous catalytic oxidation with H2O2

Diclofenac and other anti-inflammatory drugs have been detected not only in effluents of sewage treatment plants, hospitals and nursing homes but also in rivers and lakes. The heterogeneous catalytic oxidation was investigated for degradation of diclofenac. The kinetic of the degradation of the drug and of the formation of mineralization products with various heterogeneous catalysts has been studied. From the nature of the intermediate products a reaction path via hydroxylation, dehalogenation and cleavage of the NH-bridge between the aromatic rings is proposed. Subsequent oxidative ring opening and stepwise degradation lead to carboxylic acids.