Degradation of monoethanolamine by electron beam irradiation: Kinetic study and comparison with O₃ and UV AOPs

This study investigated the removal efficiency of MEA by the established AOPs (O₃/H₂O₂ and UV/H₂O ₂) and electron beam irradiation process. Since large ozone doses or high energy inputs were required even for incomplete MEA removal, it was found that MEA was difficult to treat with the general AOPs. However, the electron beam irradiation was efficient at degrading the MEA and the removal kinetics of MEA followed the pseudo first order. Although MEA was mainly degraded by the reaction with the OH• in the electron beam process, the e^- _aq also contributed to MEA removal and the rate constant between MEA and e^-_aq at pH 11 was predicted from this study. The NH₄⁺, a byproduct of the degradation of MEA, was produced during the electron beam irradiation. The effect of the initial pH values on the MEA removal efficiency was negligible, but the pH value decreases due to the degradation of MEA and the formation of acidic compounds after irradiation. The BOD₅/COD ratio was used as a biodegradability indicator and the energy consumption was evaluated by the EE/O values. Consequently, the electron beam process is proposed as a strong candidate among AOPs in removing high concentrations of MEA.