Decomposition of 2,4-dichlorophenoxyacetic acid by ozonation, ionizing radiation as well as ozonation combined with ionizing radiation

Electron beam (EB), ozone (O-3) and the combination EB/O-3 were used to study the oxidative decomposition of 2,4-dichlorophenoxyacetic acid (2,4-D) in local tap water. Using an EB treatment, a dose of 10 kGy was required for complete 2,4-D degradation, and a 90% conversion of organic chlorine into chloride ions. Using additionally 1.33 mmol dm(-3) O-3 during irradiation, the same result was achieved with a dose of 2.7 kGy. The yields of products acetate and for-mate were almost doubled by the combined EB/O-3 treatment, compared to those obtained with the same dose by EB irradiation. Gamma radiolysis showed that the degradation dose was proportional to the initial concentration of 2,4-D in the range of 50-2260 mumol dm(-3). (C) 2003 Published by Elsevier Ltd.