The Cation Effect on the Free Volume and the Solubility of H2S and CO2 in Ionic Liquids Based on Bis(2-Ethylhexyl) Sulfosuccinate Anion

Abstract

Herein, we report for the first time a study dedicated to acidic gases’ solubility in ionic liquids with sterically hindered bulky anion, namely bis(2-ethylhexyl) sulfosuccinate ([doc]), experimentally evaluated at low pressures. The effect of cation change (imidazolium, pyridinium, and pyrrolidinium) on the thermophysical properties and sorption capacities was also discussed. The densities and the activation energies of the tested ILs exhibited minor differences. Furthermore, the COSMO-RS model was used to predict the free volumes of ILs aiming to investigate its influence on gas solubilities. The conducted calculations have revealed an antibate correlation between the fractional free volume (FFV) and Henry’s law constant. In particular, the lowest FFV in 1-methylimidazolium [doc] corresponded to the minimal sorption and vice versa. In addition, it was shown that the presence of protic cation results in a significant reduction in CO2 and H2S solubilities. In general, the solubility measurement results of the synthesized ILs have shown their superiority compared to fluorinated ILs based on the physical absorption mechanism.

The Influence of Polycation and Counter-Anion Nature on the Properties of Poly(ionic liquid)-Based Membranes for CO2 Separation

“…Ionic liquids (ILs) have been attracting much attention in the field of membrane gas separation [ 10 ] since the first report of CO 2 capture by this class of salts [ 11 ]. Liquid at ambient conditions ILs, also known as room temperature ionic liquids (RTILs) [ 12 ], have been widely studied as liquid phase absorbent of CO 2 in supported liquid membranes (SILMs) [ 13 , 14 , 15 , 16 , 17 , 18 ], mixed matrix membranes (MMMs) [ 19 ] and in advanced materials based on inorganic oxides for CO 2 capture [ 20 , 21 ]. SILMs are obtained by impregnating RTILs into porous polymer supports, and MMMs are synthesized by mixing RTILs with polymer solution before membrane casting.…”