An experimental investigation on the influence of NaCl on the solubility of CO2 in (N,N-dimethylmethanamide + water)

New experimental results are presented for the solubility of carbon dioxide in aqueous solutions of N,N-dimethylmethanamide {=N,N-dimethylformamide, (CH3)2NC(H)O, DMF} and sodium chloride at temperatures of (314, 354, and 395) K, gas-free and salt-free solvent mixture DMF mole fractions of about (0.05, 0.1, and 0.25, respectively), and two salt molalities (about 2.2 and about 4.5 mol/kg water). The maximum pressure of the new experimental gas solubility data reaches nearly 10 MPa. The experimental work is to provide a data base for developing and testing thermodynamic models to describe the solubility of gases in salt-free and salt-containing mixed aqueous solvents, as well as to test screening methods based, for example, on molecular simulation. A particular thermodynamic model that combines a model for the solubility of CO2 in aqueous solutions of NaCl with a model for the solubility of CO2 in aqueous solutions of DMF is used to predict the influence of NaCl on the solubility of CO2 in aqueous solutions of DMF. The new experimental data are compared with such predictions and with calculations from an extension of that model (where a single ternary parameter for interactions between the three solutes (i.e., CO2, NaCl and DMF) is introduced and fit to the new experimental data.

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► Solubility of carbon dioxide in aqueous solutions of an organic solvent (DMF) and a strong electrolyte (NaCl).
► Range: mole fraction DMF in water: 0.05, 0.10, 0.25; molality NaCl in water: 2.2, 4.8; 314–395 K; up to 10 MPa.
► Prediction and correlation results.
► Volume expansion of liquid phase by dissolved carbon dioxide.