Mineralization of Drugs in Aqueous Medium by Advanced Oxidation Processes

At present chemical (AOPs) and electrochemical (EAOPs) advanced oxidation processes with ability to destroy organic pollutants in waters are being developed. These methods are based on the production of hydroxyl radical ((OH)-O-center dot) as oxidant. In AOPs (OH)-O-center dot radical can be obtained from Fenton's reaction between Fe2+ and H2O2 added to the medium, photoreduction of Fe3+ species or reaction between ozone and Fe2+. In EAOPs this radical is formed from water oxidation on the surface of a high O-2-overvoltage anode and/or Fenton's reaction between Fe2+ added to the medium and H2O2 electrogenerated at the cathode by the two-electron reduction of oxygen. The present work reports the mineralization of several aromatic drugs such as paracetamol, ibuprofen, clofibric acid and salicylic acid by AOPs based on ozonation catalyzed by Fe2+, Cu2+ and/or UVA light and EAOPs like anodic oxidation, electro-Fenton and photoelectro-Fenton, which are environmentally friendly electrochemical methods. For the latter processes, the drug decay with time and the evolution of aromatic intermediates and generated carboxylic acids are studied. Anodic oxidation is only effective when a boron-doped diamond (BDD) anode is used, whereas the photoelectro-Fenton process with Fe2+, Cu2+ and UVA light is the most potent method to completely destroy the drugs. The combined use of catalysts Fe2+, Cu2+ and UVA light in catalyzed ozonation also leads to overall decontamination of drug solutions.