Kinetics of Carbon Dioxide Absorption into Aqueous Amino Acid Salt: Potassium Salt of Sarcosine Solution

The kinetics of CO2 absorption into an unloaded aqueous solution of the potassium salt of sarcosine (KSAR) was studied using a string-of-disks contactor for the concentration range of 1.0-4.0 kmol m(-3) and temperatures of 25-62 degrees C. The zwitterion and termolecular mechanisms were reinterpreted to account for nonidealities in salt systems due to the effect of ionic strength through the introduction of an ionic factor, k(ion), Both models adequately represent the experimental data with no practical difference. The reaction rate constant for KSAR is high but comparable to values for amines. It increases considerably with temperature and concentration. The reaction order varies with KSAR concentration from 1.25 to 1.81, with an overall average value of 1.58. The experimentally derived kinetic model was combined with a thermodynamic model of aqueous KSAR from Aronu et al. (Chem. Eng. Sci. 2011, 66, 2191-2198) to predict the loading dependency of the overall mass-transfer coefficient, K-G, determined in pilot-plant experiment. The predicted results show that the experimental data agree well with the pilot-plant results.