Molecular insights into the lithium extraction process with ionic liquids and tributyl phosphate as co-extractants in different solvent environments

SY Jiang and K Liu and YY Yi and TM Fang and JH Zhang and KL Diao and ZZ Ding and XM Liu, CHEMICAL ENGINEERING JOURNAL, 519, 165445 (2025).

DOI: 10.1016/j.cej.2025.165445

This study constructed diverse cluster configurations in different solvent models to understand the roles of ionic liquids (ILs) and tributyl phosphate (TBP) in the Li extraction process. By analyzing the types, intensities, and locations of interactions among IL, Li+, HBO, and the constituent fragments of TBP via Electrostatic Potential (ESP), Independent Gradient Model based on Hirshfeld partition (IGMH), and binding energy assessments, the performance of various solvent models, including NMPPRNTf2, C2mimNTf2, C4mimNTf2, C8mim NTf2, N4444NTf2, N8888NTf2, P4444NTf2, and P8888NTf2, was evaluated. Findings showed that solvent models affect the formation of LiNTf2.mTBP.nH2O (m, n = 0, 1, 2, 3) cluster structures. Li complexes were tetrahedrally arranged, and the number of bound TBP and H2O molecules impacted intermolecular interactions. Interactions between Li+ and the P--O in TBP, H-O in H2O, and S--O, S-N in NTf2- promoted the cationic exchange process. Our findings indicate that the ILs C2mimNTf2, C8mimNTf2, and N4444 NTf2/P4444NTf2 exhibit good performance in the synergistic extraction process with TBP. In summary, our work deepened the understanding of IL-based Li extraction mechanisms, offering valuable insights for developing future Li extraction processes using ILs.

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