Extraction separation of copper and cobalt dependent on intermolecular interaction between Cyanex302 and Cyphos IL101

摘要

The mixed extractants are promising for the separation of complex multi-metal solutions due to their specific intermolecular interaction. In this work, the mixtures of Cyanex302 (C302) and Cyphos IL101 (IL101) were used to separate Cu(II)/Co(II) by adjusting the mole fraction of IL101 (XIL101) and the separation factor of copper over cobalt can be improved compared with the individual C302. The FT-IR combined with NMR analysis indicated that the dimeric C302 can completely dissociate at XIL101 > 0.3 and form C302-IL101 adduct due to their molecular interactions. Based on the two-dimensional correlation analysis of IR spectra (2D-COS IR), four molecular environments of the P-OH group can be found in the mixed systems with varied XIL101, including C302 monomer, C302 dimer, IL101-C302 adduct, adduct of C302 with IL101 ion clusters. Although these formed adducts present an anti-synergism for the extraction of metal ions, the separation of Cu over Co can be greatly improved because the co-extraction of Co is evidently depressed. Small-angle X-ray scattering analysis showed that the aggregates of individual IL101 and C302 systems have a similar ellipsoid morphology with different sizes, whereas the mixtures of IL101 and C302 present a spherical structure. These results will be helpful for the design of efficient extractants for the complex separation systems.