Measurement and prediction model of carbon dioxide solubility in aqueous solutions containing bicarbonate anion

The solubility of CO2 in aqueous solutions containing bicarbonate anion was determined at 308.15, 328.15, 368.15, and 408.15 K up to 40 MPa. In comparison with Cl−, HCO3− has a larger size and higher molecular weight, which leads to the opposite salting-out effect. HCO3− can suppress CO2 dissolution because of equilibrium reaction between CO2 and H2O to form HCO3−. Cooperation of the three effects leads to slightly variable solubility of CO2 in the solution containing HCO3−. It is found that the Duan model can more accurately predict the CO2 solubility at low salt concentration, while the PR–HV model shows smaller error at high salt concentration. Moreover, the solubility of CO2 in natural ground water was measured at different temperatures and pressures, and the results verified the presented mathematical model.

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