CFD comparison of novel [emim][DCA] and [emim][MS] ionic liquids for the separation of CO2 greenhouse gas in the membrane contactor

Abstract

Global warming (resulted by the abnormal emission of CO₂) has recently been an important global subject of concern due to its detrimental effects on the human well-being. Therefore, developing novel and cost-effective procedure for mitigating the CO₂ release into the atmosphere is of prime importance. Recently, the employment of ionic liquids (ILs) for increasing the removal proficiency of CO₂ in membrane-based processes has been a hot research topic among scientists. The emergence of indisputable positive points such as eco-friendliness, low flammability and negligible volatility have made the ILs a promising alternative for benchmark amine solutions. In this paper, the authors have made their effort to propose a numerical model following to a computational fluid dynamics (CFD) simulation for estimating the separation percentage of CO₂ pollutant using 1-ethyl-3-methylimidazolium dicyanamide ([emim][DCA]) and 1-ethyl-3-methylimidazolium methylsulfate ([emim][MS]) ILs in the hollow fiber membrane contactor (HFMC). Comparison of model outcomes with experimental-based results shows an appropriate agreement with absolute relative error (ARE) less than 5%.

Keywords: CO2 separation; Mathematical modeling; Membrane contactor; Novel ionic liquids; Simulation.

Fig. 1

Molecular structure of employed ILs [https://www.sigmaaldrich.com/GB/en/product/aldrich/18086; https://solvionic.com/en/ionic-liquids/5746-1-ethyl-3-methylimidazolium-dicyanamide.html].

Fig. 2

Mass transfer mechanism, geometry and module cross section. Adapted from.

Fig. 3

Model validation based on the evaluation of simulation results and experimental data for the.

Fig. 4

Model validation based on the evaluation of simulation results and experimental data for the CO₂ removal percentage in different operational time. Experimental data was made by Sohaib et al.. Q_g=20 ml min^− 1.

Fig. 5

CO₂ concentration profile in the tube side using (a) [emim][MS] and (b) [emim][DCA]. The figure has been created using COMSOL Multiphysics software version 6.

Fig. 6

Dimensionless concentration of CO₂ in the tube-membrane interface of contactor.

Fig. 7

The role of module length increment on the removal efficacy of CO₂.

Fig. 8

Impact of porosity on the CO₂ separation performance.

Fig. 9

Effect of hollow fibers’ number on the CO₂ separation percentage.

Fig. 10

Effect of hollow liquid flow rate on the CO₂ separation percentage.