γ-Radiation effect on Th4+ extraction behaviour of TODGA/[C2mim][NTf2]: identification and extractability study of radiolytic products

Abstract

The γ-radiation effect on Th⁴⁺ extraction by N,N,N′,N′-tetraoctyldiglycolamide (TODGA)/1-ethyl-3-methylimidazoliumbis (trifluoromethylsulfonyl) imide ([C₂mim][NTf₂]) and TODGA/dodecane was evaluated through the quantitative analysis of TODGA content and identification of the radiolytic products. In addition, the density functional theory (DFT) calculations of extractability for the first time. The Th⁴⁺ partitioning of TODGA/[C₂mim][NTf₂] from 0.01 M HNO₃ was near 98.6% at 1000 kGy, which was much higher than that in TODGA/dodecane (16.3%). The content of TODGA in diluent after irradiation was quantified using UPLC-Q-TOF-MS. The results showed that the [C₂mim][NTf₂] did not have the ability to protect the TODGA molecular comparing with the dodecane. However, TODGA in [C₂mim][NTf₂] prefers to react with the [C₂mim]⁺ radical under γ-radiation, and that in dodecane prefers degradation according to radiolytic products identification. Moreover, the DFT calculations presented that the substituted compounds formed in TODGA/[C₂mim][NTf₂] was responsible for partially keeping the extraction ability for Th⁴⁺.