A Study on the Influence of Na2SO4 on the Solubility of CO2 in Aqueous Solutions of (N,N-dimethylmethanamide)

The influence of sodium sulphate on the solubility of carbon dioxide in aqueous solutions of N,N-dimethylmethanamide {= N,N-dimethylformamide, (CH3)2N-C(H)O, DMF} was investigated experimentally at three temperatures (314 K, 354 K, and 395 K). The solvent was an aqueous solution of DMF (mole fraction of DMF in the salt-free solution ≈ 0.05) and sodium sulphate (molality ≈ 0.6 mol·(kgH2O)−1). The maximum pressure of the new experimental gas solubility data reaches nearly 10 MPa. A thermodynamic model that combines two models for the solubility of CO2 (in aqueous solutions of Na2SO4 on one side and in aqueous solutions of DMF on the other side) is used to predict the influence of Na2SO4 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, Na2SO4, and DMF) is adjusted to improve the representation of the experimental data.