ADVANCED OXIDATION OF THE PHARMACEUTICAL DRUG DICLOFENAC WITH UV/H2O2 AND OZONE

Diclofenac, a widely used anti-inflammatory drug, has been found in many Sewage Treatment Plant effluents, rivers and lake waters, and has been reported to exhibit adverse effects on fish. Advanced oxidn. processes, ozonation and H2O2/UV were investigated for its degrdn. in water. The kinetics of the degrdn. reaction and the nature of the intermediate products were still poorly defined. Under the conditions adopted in the present study, both ozonation and H2O2/UV systems proved to be effective in inducing diclofenac degrdn., ensuring a complete conversion of the chlorine into chloride ions and degrees of mineralization of 32% for ozonation and 39% for H2O2/UV after a 90 min treatment. The reactions followed similar, but not identical, reaction pathways leading to hydroxylated intermediates (e.g. 2-[(2,6-dichlorophenyl)amino]-5-hydroxyphenylacetic acid) and C-N cleavage products (notably 2,5-dihydroxyphenylacetic acid) through competitive routes. Subsequent oxidative ring cleavage leads to carboxylic acid fragments via classic degrdn. pathways. In the pH range 5.0-6.0 kinetic consts. (1.76´104-1.84´104 M-1 s-1) were estd. for diclofenac ozonation.