The solubility of CO2 in two biodegradable ionic liquids tris(2-hydroxyethyl)methylammonium methylsulfate [THMA][MeSO4] and 2-hydroxyethyl-trimethylammonium lactate [2HETMA][Lac] has been studied experimentally. A synthetic method was used to measure bubble-point pressures up to 8 MPa for a temperature range of 313 K to 363 K. The solubility of CO2 in [2HETMA][Lac] is much higher than in [THMA][MeSO4], but the solubility increment is lower at higher CO2 concentrations. The solubility of CO2 in [THMA][MeSO4] is much lower compared to ionic liquids containing the same anion, but lacking hydroxyl-groups in the cation. The hydroxyl-groups required for the biodegradability of the IL have a detrimental effect on the CO2 solubility. [THMA][MeSO4] and [2HETMA][Lac] are not suitable for CO2 capture and can be considered as an example of a contradictive design where the biodegradability is improved upon introducing hydroxyl-groups, while the CO2 solubility is reduced significantly. The experimental data has been modeled with good accuracy using the Peng Robinson equation of state in combination with the Wong Sandler mixing rules.
The table above is generated from the ThermoML associated json file (link above).
POMD and RXND refer to PureOrMixture and Reaction Datasets. The compound numbers are included in properties, variables, and phases, if specificied;
the numbers refer to the table of compounds on the left.