Experimental and thermodynamic study of CO2 solubility in promising [TF2N and DCN] ionic liquids

The solubility of carbon dioxide (CO2) in three different ionic liquids {1,2,3-Tris(diethylamino) cyclopropenylium dicyanamide, [TDC] [DCN]; ethyldimethylpropylammonium bis (trifluoro methyl sulfonyl)imide, [EMMP] [TF2N]; and 1,2,3-Tris(diethylamino)cyclopropenylium bis(trifluoro methane sulfonyl)imide, [TDC] [TF2N]} has been studied experimentally using a gravimetric microbalance. The CO2 + IL systems were studied at 313.15, 323.15 and 333.15 K and over a pressure range of 10.1-20 bar. The experimental density, Henryʹs law constant, entropy and the enthalpy of absorption for CO2 are also reported. The results obtained showed that CO2 solubility diminished in the following sequence: [TDC][TF2N] > [EMMP][TF2N] > [TDC][DCN]. It was found that [TDC][TF2N] shows comparable CO2 solubility to other well-known ionic liquids such as [hmim][TF2N], which makes it an attractive solvent for CO2 removal processes. The experimental solubility of CO2 in the three solvents were well correlated using the standard Peng–Robinson (PR) EoS, the Soave–Redlich–Kwong (SRK) EoS with quadratic mixing rules, and the Non-Random Two-Liquid (NRTL) model.