Equilibrium Solubility of CO2 in Aqueous Potassium Taurate Solutions:  Part 2. Experimental VLE Data and Model

The solubility of CO2 in aqueous potassium taurate solutions was measured at 298 and 313 K. Crystallization of the protonated amine (one of the reaction products) was observed during the absorption of CO2 in concentrated amino acid salt solutions. The influence of crystallization on the equilibrium CO2 absorption capacity of the amino acid salt solution was investigated. The difference in the thermodynamic characteristics of the aqueous amino acid salt solution and aqueous alkanolamines is discussed using the Deshmukh−Mather model (Deshmukh, R. D.; Mather, A. E. Chem. Eng. Sci. 1981, 36, 355). Because of a limited change in the ionic strength of the solution in the range of the measured CO2 loading, a simplified model similar to the one proposed by Kent and Eisenberg (Kent, R.; Eisenberg, B. Hydrocarbon Process. 1976, 55, 87) is used to interpret the solubility data. In addition, the equilibrium constant of the carbamate hydrolysis reaction was experimentally measured for monoethanolamine and the potassium salt of taurine at 298 K.