Solubility and electrochemical determination of CO2 in some dipolar aprotic solvents

The solubility of CO2 in some solvents of electrochemical interest was measured both as a function of its partial pressure and as a function of temperature. Henry constants determined at 298.15 K are reported for DMF, AN, DMSO and THF. The solubility of CO2 in these solvents is also reported at various temperatures in the range -10 to 25 °C (20 to 50 °C for DMSO). The Gibbs energy, enthalpy and entropy of solution at 298.15 K and 1 atm partial pressure of CO2 were estimated from the temperature dependence of the solubility. The effect of base electrolytes on the solubility of CO2 was also investigated. Voltammetric investigations of CO2 reduction showed that, in spite of the large dependence of the peak potential on the nature of the electrode material, the solvent and the background electrolyte, the peak current is proportional to the CO2 concentration, thus providing a means of quantitative CO2 determination.