Solubility of CO2 in aqueous solutions of diethanolamine (DEA) and choline chloride

Abstract

In this study, the solubility of CO2 in DEA in the presence and absence of choline chloride was reported at different temperatures of 276.15, 298.15, 313.15, and 333.15 K, and pressure range of 4-15 bar. The solubility of CO2 was evaluated using the pressure decay method in a batch isochoric stirred absorption cell. Also, the design of experiments performed with Qualitek-4 software using the Taguchi method. Henry’s law constants at three different temperatures were calculated from the correlation of solubility data. Results showed that increasing the initial pressure and DEA concentration and also decreasing the temperature, increases the solubility of CO2. Optimum operating conditions to maximize the amount of CO2 absorption including the temperature of 276.15 K (minimum level), the initial pressure of 15 bar (maximum level), the concentration of DEA of 40 wt.% (maximum level), and the concentration of choline chloride of 5 wt.% (middle level). Also, Qualitek-4 software predicted the amount of solubility at the optimum conditions which was 7.5% different from the measured value.