Solubilities of Five Lithium Salts in 1-Butyl-3-methylimidazolium Dicyanamide and in 1-Butyl-3-methylimidazolium Tetrafluoroborate from 298.15 to 343.15 K

Solubilities were measured for five lithium salts (LiF, LiCl, LiBr, LiPF6, and LiTFSI) in 1-butyl-3-methylimidazolium dicyanamide ([BMIM][N(CN)2]) and in 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]) from 298.15 to 343.15 K under atmospheric pressure. Measurements were made using inductively coupled plasma-optical emission spectroscopy (ICP-OES). Solubilities increase with rising temperature. The highest solubility is for LiPF6, followed by LiTFSI, LiBr, LiCl, and LiF. In both ionic liquids, LiF is essentially insoluble. A comparison of the solubilities of the same salts in different [BMIM]-based ILs shows that the solubility order is [BMIM][OTf] < [BMIM][BF4] < [BMIM][N(CN)2]. The new data were correlated by the Margules equation where the standard state for the salt’s activity coefficient is the hypothetical pure liquid salt. Estimates are given for total enthalpy, entropy, and Gibbs energy of dissolution.