Solubility of H₂S in Ionic Liquids 1-Ethyl-3-methylimidazolium Hexafluorophosphate ([emim][PF₆]) and 1-Ethyl-3-methylimidazolium Bis(trifluoromethyl)sulfonylimide ([emim][Tf₂N])

Abstract

The solubility of hydrogen sulfide gas in ionic liquids (ILs) 1-ethyl-3-methylimidazolium hexafluorophosphate ([emim][PF6]) at temperatures from (333.15 to 363.15) K and 1-ethyl-3-methylimidazolium bis(trifluoromethyl)sulfonylimide ([emim][Tf2N]) at temperatures ranging from (303.15 to 353.15) K and pressures up to about 2.0 MPa was measured using a volumetric based static apparatus. The solubility data were correlated using two models: the Krichevsky−Kasarnovsky (KK) equation, and the extended Henry’s law combined with the Pitzer’s virial expansion for the excess Gibbs energy. Henry’s law constants (at zero pressure) were obtained at different temperatures from the obtained experimental solubility data. Using the solubility data, the partial molar thermodynamic functions of solution, that is, Gibbs energy, enthalpy, and entropy were calculated. A comparison showed that the solubility of H2S in [emim][Tf2N] is greater than [emim][PF6].