Radical-induced destruction of diethyl phthalate in aqueous solution: kinetics, spectral properties, and degradation efficiencies studies

Abstract

In this work, the reactions of ^∙OH, e ⁻_aq , and SO ^∙−₄ with diethyl phthalate (DEP) were investigated in aqueous solution by pulse radiolysis, and degradation efficiencies of DEP with ^∙OH and e ⁻_aq were evaluated in water using steady-state radiolysis as well. The absolute rate constants of ^∙OH, e ⁻_aq , and SO ^∙−₄ with DEP were determined as 2.3 × 10⁹, 1.0 × 10¹⁰, and 1.0 × 10⁸ M⁻¹ s⁻¹, respectively. The degradation efficiencies for the ^∙OH and e ⁻_aq reactions were 81 and 33 %, respectively. Transient absorption spectra were observed for the intermediate radicals produced by ^∙OH, e ⁻_aq , and SO ^∙−₄ reactions. The results suggested that e ⁻_aq transferred to the ester group, resulting in the formation of DEP radical anions. In contrast, ^∙OH and SO ^∙−₄ added predominantly to the aromatic ring of DEP, forming the corresponding ^∙OH adducts. The fundamental mechanistic parameters and degradation efficiencies derived from these results were significant for evaluations and applications of advanced oxidation processes.