Kinetics and Modelling of Dichloroacetic Acid Oxidation Using Ozone and UV Radiation

LOVATO MARTÍN CASSANO

Praga, República Checa

Congreso; 6th European meeting on Solar Chemistry and Photocatalysis: Environmental Applications (SPEA6); 2010

Dichloroacetic Acid (DCA) is a water pollutant very often found as a DPB of natural water chlorination resulting from the combination of free chlorine with humic substances regularly present. Ozone is an oxidizing agent showing a high reactivity with a large number of organic compounds. The reaction of ozone with organic substrates follows two reaction mechanisms: (i) direct reaction of molecular ozone and (ii) indirect reactions involving radicals formed in the ozone decomposition in water. The direct oxidation by ozone molecule is selective to unsaturated electron-rich bonds contained in specific functional groups, but relatively slow. On the other hand, indirect oxidation reaction by means of radicals proceeds at a faster rate but with low selectivity, which makes this reaction interesting for degrading many types of organic compounds. This process occurs slowly in water, and the decomposition process can be accelerated with UV radiation, since the photolysis of ozone produces hydrogen peroxide as primary product, which can then photolyze into a hydroxyl radical directly, or can react with molecular ozone to produce the hydroxyl radical. In this work, degradation of DCA by direct photolysis, O3 alone and the O3/UV process were studied and evaluated to successfully model the reacting system. The effects of different operating variables were investigated and oxidation by-products were identified and quantified, in order to develop an operative reaction scheme.