Kinetics of CO₂ absorption into aqueous MDEA solution promoted by mixture of potassium salt of l-arginine and l-glutamic acid

Amino acid salt can be a promising alternative as the promoter for increasing the absorption kinetics rate of MDEA toward CO². In this study, the absorption kinetics of carbon dioxide (CO²) into an aqueous 40 wt% equivalent Methyldiethanolamine (MDEA) solution promoted by 1 and 5 wt% of mixed amino acid salt, potassium salt of l-arginine (Arg) and l-glutamic acid (Glu), was performed using a wetted wall column at temperatures from 303.15 to 323.15 K. Effect of various mixture ratios of those promoters on the reaction rate parameters and its physicochemical properties was investigated based on the fast pseudo-first-order regime. The reaction between CO² and amino acid was described with the zwitterionic mechanism. Aqueous MDEA without promoter was set as the control. The result revealed that the mixed promoter has affected to increase CO² absorption rate into the aqueous MDEA solution compared with the control and using the single promoter due to the interaction between Arg and Glu. In addition, the overall reaction rate constant, kov, significantly increased with the increase of mixed promoter concentration and temperature under the investigated range. The aqueous MDEA solution promoted by 5% of mixed Arg and Glu in 1:1 ratio was obtained as the best CO² absorbent.