Carbon Dioxide Absorption from Biogas by Amino Acid Salt Promoted Potassium Carbonate Solutions in a Hollow Fiber Membrane Contactor: A Numerical Study

Aqueous K2CO3 solution is a promising absorbent in removing CO2 from gas mixtures using a hollow fiber membrane contactor (HFMC). The use of amino acid salts (AASs) as a promoter in K2CO3 solutions may further improve absorption performance. In this study, a two-dimensional mathematical model was developed to simulate the CO2 absorption process in an HFMC, where potassium salts of glycinate (PG), lysine (PL), and arginine (PA) were considered as promoters in K2CO3 solution. The absorption performances of K2CO3 solutions with and without promoters were analyzed theoretically. The effects of operating parameters, such as AAS concentration, temperature, pressure, flow rate and initial CO2 content, on the absorption process were also investigated. The results showed that the use of AASs as promoters in K2CO3 solution significantly enhances the CO, absorption performance. PG-promoted K2CO3 solution outperformed the other two, as it showed the highest absorption flux and CO2 removal efficiency under any operating conditions.