Carbon dioxide capture in aqueous potassium serinate and piperazine solution using bubbling reactor for membrane contactor applications

There are various methods of CO2 removal, including absorption, adsorption, and membrane separation. A new method, membrane–solvent combination, involves the removal of CO2 using an absorbent in a membrane contactor. However, the absorbent causes membrane wetting, which reduces the CO2 removal efficiency. Accordingly, this study considered the use of potassium serinate (PS), an amino acid salt with high surface tension, to increase the surface tension of the absorbent and therefore reduce membrane wetting when used in a membrane contactor. Piperazine (Pz) was added to improve the absorption performance and prevent oxidative degradation. The concentration ranges of PS and Pz to apply at the membrane contactor were optimized based on the CO2 cyclic capacity and the calculated theoretical breakthrough pressure. Compared to a commercial CO2 absorbent, 30 wt% monoethanolamine (MEA), the PS + Pz absorbent had higher CO2 cyclic capacity and better wettability. Moreover, its oxidative degradation rate constant (k) in 720 h oxidative degradation experiments was 42.0 % lower than that of 30 wt% MEA, indicating that amino acid salt + Pz absorbents are promising for use in membrane contactors.