Electron Beam Radiolysis of Diethyl Phthalate in Aqueous Solutions

Electron beam radiolysis experiments were undertaken to gain insights into the kinetic mechanisms of diethyl phthalate (DEP) degradation in aqueous solutions. DEP degradation was found to follow pseudo-first-order kinetics. The pseudo-first-order rate constant decayed exponentially with DEP initial concentrations (C-0), whereas G values of DEP and C-0 followed linear relationship. Addition of sodium carbonate to irradiated DEP solutions reduced DEP decomposition. H2O2 was not favorable for removal of DEP. An effective degradation was achieved in both N2O-saturated and t-BuOH-containing N-2-saturated DEP solutions. High removals (>99%) were achieved at 15 kGy without these radical scavengers. Radical scavenging tests indicated that both (OH)-O-center dot and e(aq)(-) played significant roles in DEP radiolysis. Several intermediates such as monoethyl phthalate, phthalate acid, and short-chain aliphatic carboxylic acids were formed from DEP radiolytic degradation. Finally, DEP was completely mineralized when the absorbed dose was high enough. Results also indicate that electron beam radiolysis is a promising process for an efficient removal of DEP in aqueous solutions.