ADVANCED OXIDATION OF 2, 4- DICHLOROPHENOXYACETIC ACID AND DECOMPOSITION PRODUCTS

Abstract

 2, 4-dichlorophenoxyacetic acid (2, 4-D) is persistent in water environment and harmful to human body. It is reported that 2, 4-D in aqueous solution can be decomposed by the advanced oxidation process (AOP). However, no clear experimental results have been reported on the decomposition mechanism of 2, 4-D.

 This paper aims to unveil the decomposition mechanism of 2, 4-D by advanced oxidation process using H₂O₂, O₃ and UV in laboratory batch experiments. We reported previously that H₂O₂/O₃/UV and H₂O₂/UV systems are able to generate hydroxyl radical efficiently.

 The results of experiment show that 2, 4-D could be decomposed rapidly by the action of hydroxyl radical generated in H₂O₂/O₃/UV and H₂O₂/UV systems. In this case, dechlorination and degradation of 2, 4-D occurred simultaneously due to non-selective decomposition. On the other hand, selective decomposition without hydroxyl radical was occurred slowly with mineralization of 2, 4-D. In addition, the mineralization pathways of 2, 4-D were estimated from the performance of several decomposition products analyzed by LC/MS/MS and others.