Separation of Co(II) and Ni(II) Using an Analog of Glycine-Betaine Based on Task-Specific Ionic Liquids

A series of salts based on ethyl ester glycine-betaine derivatives, viz tri(n-pentyl)[2-ethoxy-2-oxoethyl]ammonium bromide, have been synthesized. These cations generate hydrophobic ionic liquids (ILs) with bis(trifluoromethylsulfonyl)imide (Tf2N−) or dicyanamide (Dca−) anions. new analogues glycine-betaine-based (AGB-ILs) were characterized using spectroscopic methods (IR, 1H, and 13C NMR) elemental analysis. AGB-ILs used for the selective separation Ni(II) Co(II) in saline media pure ILs phase diluted organic solvent. Interestingly, extraction Dca-based can be enhanced chaotropic anions such as NaNO3 (E > 90% E = 85% Ni(II)). Tf2N−-based do not extract even NaCl 4M. Dca−-based lead to a quasi-quantitative Co(II), while is limited few percent (17%) leading factors higher than 100, ensuring good both metals. Cobalt could back-extracted from liquid water an aqueous solution Na2SO4, which limits release AGB cation media, thus preserving its integrity. Results obtained by solvent comparable those phase, indicating that this strategy deployed systems working continuously out equilibrium since mechanisms involve fast equilibria.