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Aqueous amino acid salt solutions are seen as more sustainable alternative CO 2 solvents compared to conventional alkanolamines. The absorption of CO 2 into aqueous solutions of potassium L-prolinate, over the temperature range of 290−303 K, was studied using a stirred cell. To compare the effect of potassium versus sodium as counterion, the absorption rates of CO 2 in sodium L-prolinate solutions were also determined. The amino acid salt concentration was varied between 0.5 and 3 mol dm −3 . Physicochemical properties such as density, viscosity, and physical solubility of N 2 O, required in the interpretation of absorption rate experiments, were determined separately. The obtained experimental reactive absorption fluxes were interpreted, using the pseudo-first-order approach, into intrinsic reaction kinetics. The potassium-based solvent showed, on average, a 32% higher reactivity toward CO 2 than the sodium equivalent. The kinetic data were correlated in a power-law reaction rate expression. The reaction order with respect to the amino acid was found to be between 1.40 and 1.44 for both L-prolinate salts, and the second order kinetic rate constant, k 2 , was calculated for the potassium salt to be 93.7 × 10 3 dm 3 ·mol −1 ·s −1 at 298 K with an activation energy of 43.3 kJ·mol −1 . L-Prolinate salts show higher chemical reactivity toward CO 2 than most of the aminoalcohols and amino acid salts.

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Vapor−liquid equilibrium (VLE) measurements for unloaded and CO 2 -saturated aqueous potassium salt solutions of L-proline have been performed using a high-pressure equilibrium cell. The solubility of CO 2 has been determined at temperatures of 363, 393, and 403 K in 3 and 4 mol dm −3 aqueous solutions. The CO 2 partial pressures ranged from 3.0 to 358 kPa. In addition, the VLE data for CO 2 -free and CO 2 -saturated 3 mol dm −3 aqueous potassium sarcosinate solutions are presented for the same range of temperatures. The vapor pressures of the considered compounds have been determined at temperatures from 353 to 403 K. The reboiler duty required for stripping CO 2 from potassium L-prolinate solutions has been computed by the summation of the desorption enthalpy of CO 2 , sensible heat, and evaporation heat associated with co-produced regenerator overhead water vapor. A new approach to calculate the latter contribution is presented. The calculated energy requirements for L-prolinate are in the range reported in the literature for other amino acid salts.