Computational investigation on the effect of [Bmim][BF4] ionic liquid addition to MEA alkanolamine absorbent for enhancing CO2 mass transfer inside membranes

Abstract

Nowadays, various types of liquid solutions have been applied to remove acidic contaminants such as CO2 with the aim of mitigating their pernicious emission to atmosphere. Ionic liquids are recently of tremendous attention as promising solutions for CO2 molecular removal from disparate gaseous mixtures due to their superior characteristics such as regeneration simplicity, low volatility and negligible environmental toxicity. The main objective of this paper is to mathematically implement a model based on finite element approach (FEA) to analyze the governing mass and momentum partial differential equations inside the domains of polytetrafluoroethylene-co-perfluorinated alkyl vinyl ether membrane contactor (PFAMC). Also, a computational fluid dynamics (CFD) simulation is carried out to analyze the CO2 molecular removal percentage using MEA absorbent and a mixed solution containing 30% 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4]) ionic liquid and 70% MEA amine solution. The results show that although MEA has been able to remove only 18% of CO2 from the inlet gas, the addition of 30% [Bmim][BF4] ionic liquid to MEA significantly improved the CO2 mass transfer performance and consequently its removal efficiency to 79%. Study on the effect of some operational parameters such as inlet feed gas flow rate, packing density and number of hollow fibers on removing the CO2 molecules is another objective of this paper.