Radiation-induced degradation of di-butyl phthalate plasticizer in aqueous solution: Performance, pathways and toxicity assessment

Di-butyl phthalate (DBP), a widely used plasticizer, is ubiquitous in aquatic environments due to the widespread application of plastics. Moreover, DBP is refractory and difficult to remove in biological wastewater treatment process. In this study, radiation-induced degradation of DBP was investigated. The results showed that when the initial DBP concentration was 5-15 mg/L, the DBP degradation efficiency was more than 72% at the absorbed dose of 0.1 kGy, and the degradation of DBP followed a first-order kinetic model. The quenching experiments suggested that center dot OH, H center dot, and eaq- were all involved in the DBP degradation, and center dot OH played a major role. The acidic condition (pH = 3.5) was more conducive to DBP degradation. The existence of inorganic anions (HPO42-, Cl-, NO3-, or CO32-) and organic compounds (humic acid, peptone, or D-glucose) inhibited DBP degradation. The addition of oxidants (Fe2+, H2O2, PDS, PMS, or Fe2+/H2O2) could promote DBP degradation. Thirteen intermediate products were identified by LC-MS and the possible pathways of DBP degradation were inferred. The toxicity of DBP and its intermediates were predicted by ECOSAR. Most of the intermediates were less toxic than DBP, indicating the effectiveness of radiation degradation of DBP in reducing its toxicity. This study revealed that radiation is a promising technology for the effective degradation of DBP in aqueous solution.