Kinetics and mechanisms studies on dimethyl phthalate degradation in aqueous solutions by pulse radiolysis and electron beam radiolysis

The kinetics and mechanisms of hydroxyl radical/hydrated electron reactions with dimethyl phthalate (DMP) were investigated using pulse radiolysis and electron beam radiolysis techniques. The bimolecular rate constants for the reaction of hydroxyl radical and hydrated electron with DMP were measured to be 3.4×109 M−1 s−1 and 1.6×1010 M−1 s−1 under pulse radiolysis experiments, respectively. The major products after radiation were elucidated by LC/MS/MS and ion chromatography analysis. It was found that DMP degradation had different mechanisms in oxidative and reductive conditions: hydroxyl radical attacked aromatic ring of DMP leading to the fracture of benzene ring, formed a series of byproducts which were completely mineralized while hydrated electron attacked the ester group of DMP, formed the product of phthalic acid in reductive conditions.