Absorption of carbon dioxide in an aqueous solution of protic ionic liquid [MEA][Gly]: Experimental study and model fitting

Document Type : Research Article


Chemical Engineering Department, Kermanshah University of Technology, Kermanshah, Iran.


Relatively high viscosities of protic ionic liquids limit their industrial applications in carbon dioxide removal processes. For this purpose, the equilibrium absorption of carbon dioxide was studied in an aqueous solution of ionic liquid-based on anionic glycine amino acid, [MEA][Gly], in a temperature range of 303.15 to 323.15 K and different equilibrium pressures. It was found that at a constant temperature of 313.15 K, by increasing the presence of water in the solution from 80% to 95% wt%, the CO2 absorption loading enhances from 1.36 (mol/ mol) to 2.24 (mol/ mol), which is a 64% increase in the loading. Using a quadratic equation, correlations of solubility as a function of CO2 partial pressure for all the studied solvent concentrations were developed, so that the calculated results showed a good agreement with the experiments. In addition, density, and viscosity measurements of [MEA][Gly] in the range of 303.15 to 323.15 K at atmospheric pressure showed that as the amount of water in the solution decreases, their corresponding values increase substantially. Applying the empirical correlations, the values of density and viscosity were estimated in terms of temperature and mole fractions. Moreover, the Clausius-Clapeyron equation was applied to compute the heat of CO2 absorption into the aqueous solution of [MEA][Gly]. Finally, although [MEA][Gly] is introduced as a novel absorbent in carbon dioxide removal processes, high concentrations of this solvent are not suitable for carbon dioxide capture and removal, mainly due to its high viscosity.


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