Radiolysis of carbamazepine aqueous solution using electron beam irradiation combining with hydrogen peroxide: Efficiency and mechanism

• Radiolytic degradation of CBZ with and without H2O2 was both studied.
• A removal efficiency of 100% of 75 mg L−1 CBZ could be observed within 20 kGy absorbed dose with the absence of H2O2.
• A proper H2O2 additive could promote the degradation efficiency and mineralization level of CBZ.
• The transformation products were different between the two solution systems.
• Possible transformation pathways of CBZ under irradiation coupling with H2O2 were proposed.

Herein, ionizing radiolytic treatment for CBZ in the absence of and in the presence of H2O2 was both studied. Although use of electron beam irradiation alone could efficiently decompose CBZ, combination with H2O2 could further promote degradation efficiency and mineralization level of CBZ. In the present study, the best degradation efficiency of CBZ was obtained in solution with 10 mM H2O2, where the dose constant was 2.63 kGy−1; while the highest mineralization level (41% TOC removal) was achieved in solution with 50 mM H2O2. Five carboxylic acids and twelve organic transformation products (TPs) were identified and determined during the irradiation processes. On the basis of the tendency of TPs, possible transformation mechanisms of CBZ with the combinative processes of electron beam and H2O2 were proposed. It was found some mutagenic and carcinogenic transformation compounds, such as acridine (ACIN) could be promptly decomposed in the presence of H2O2.