Investigation of the synergistic extraction behavior between cerium (III) and two acidic organophosphorus extractants using FT-IR, NMR and mass spectrometry

[Display omitted] •A novel PC 88A+D2EHPA-dimer combined via hydrogen bond interactions was discovered.•The chelating form and orgnic structure of Ce-complexes were proposed.•An advanced comprehensive method was applied for the study of orgnic reaction mechanism and extraction behaviors. The synergistic solvent extraction of cerium (III) using two acidic organophosphorus extractants, 2-ethylhexylphosphonic mono-2-ethylhexyl ester (PC 88A) and di-2-ethylhexyl phosphoric acid (D2EHPA), in a chloride medium was investigated using spectroscopic analyses. The mixture systems exhibited a synergistic effect on the extraction of Ce(III), and the synergism was due to the generation of a novel dimer, which combined with the PC 88A and D2EHPA unimer through hydrogen bonding interactions. The polymerization state and conformation of the PC 88A and D2EHPA were analyzed using fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance spectroscopy (NMR) and mass spectrometry (MS), and the organic structure and composition of the extraction complexes were also characterized. Furthermore, the chelating forms of the complexes in the synergistic system were determined and explained using spectral data. During the extraction process, each Ce combined with three dimers of the extractant and released three H+, and the Ce cation exchanged with the POH group and coordinated with the PO group.