Gamma Radiation Effect on Heterocyclic N-Donor Ligands in Ionic Liquids

The radiation stability of separation systems for spent nuclear fuel reprocessing is an important problem to be solved before their practical use. In this work, the γ radiation effects on three commonly used heterocyclic N-donor ligands in ionic liquids(IB-BTP/［C₂mim］［NTf₂］, CA-BTP/［C₂mim］［NTf₂］ and CA-BTPhen/［C₂mim］［NTf₂］) were systematically studied by using Fourier transform infrared spectroscopy(FTIR) and ultra-high performance liquid chromatography/quadrupole time-of-flight mass spectrometry(UPLC/Q-TOF-MS). The changes in extraction performance of Eu³⁺ before and after irradiation were also compared. The results show that in the presence of ［C₂mim］［NTf₂］ ionic liquid, the order of the radiation stability of the three extracting agents is CA-BTP>IB-BTP≈CA-BTPhen; the main radiolysis products of the three systems are substitution products formed by heterocyclic N-donor ligands and radicals from ［C₂mim］［NTf₂］ ionic liquids(·CF₃, ·［C₂mim］⁺,  ·H, etc.). Even at an absorbed dose of up to 300 kGy, good extraction performances are still maintained.