A modified semi-empirical model for correlating and predicting CO2 equilibrium solubility in aqueous 2-[2-(dimethylamino)ethoxy]ethanol solution

Abstract

Amine-based post-combustion capture is considered an effective method to control CO2 emissions from industrial flue gases, but some improvements are still needed for its widespread use. Looking for low-corrosive sorbents for steel, we decided to investigate the properties of the tertiary amine 2-[2-(dimethylamino) ethoxy] ethanol (DMAEE), and in particular its CO2 equilibrium solubility at temperature in the range 298.15–323.15 K and CO2 partial pressure between 5.0 and 60 kPa. A correction factor based on the physical solubility was applied to modify the Kent-Eisenberg model and then to predict the CO2 solubility in DMAEE solution, and the absolute average deviation (AAD) between the prediction and the experimental data was found to be 3.0%, lower than that obtained by reported Kent-Eisenberg, Austgen, Hu-Chakma, and Li-Shen models. The proposed model was then further correlated with published solubility data of four other tertiary amines, and the results indicate that the proposed semi-empirical model can be used for these amines with acceptable AADs. In addition, the heat of CO2 absorption and the dissociation constant (pKa) were also systematically evaluated and compared with other reported amines, and the obtained results indicate that DMAEE has the potential to be a suitable absorbent for post-combustion CO2 capture.