Experimental and theoretical investigation of equilibrium absorption performance of CO₂ using a mixed 1-dimethylamino-2-propanol (1DMA2P) and monoethanolamine (MEA) solution

Reliable equilibrium solubility data and consistent thermodynamic models for CO₂ in novel amine solutions are necessary to design and simulate the CO₂ capture process. In this study, the first experimental data for the equilibrium solubility of CO₂ in a mixed 1-dimethylamino-2-propanol (1DMA2P) and monoethanolamine (MEA) aqueous solution are reported. The experiments were performed over a CO₂ partial pressure of 3–186 kPa, at a total concentration of 2.5 M, and at two different temperatures (313.15 and 333.15 K). The CO₂ solubility data were measured using a static-synthetic method based on the material balance method. The extended-universal quasi-chemical (e-UNIQUAC) model was applied to predict the experimental data. The adjustable parameters were either obtained from the model or taken from the literature for experimental binary, ternary, and quaternary systems. Moreover, the species concentration in the liquid phase, activity coefficients, solution pH, and solution ionic strength were predicted. The experimental results show that the CO₂ absorption capacity increases as the blend mole ratio of 1DMA2P/MEA increases. An acceptable error was obtained between the experimental data and the model-predicted values, with an absolute average relative deviation of 22.4%. The e-UNIQUAC model employed in this study can be used to simulate the CO₂ absorption process by the 1DMA2P-MEA solution.