Kinetics of carbon dioxide absorption into aqueous [Hmim][Gly] solution

• The CO2 absorption/desorption properties in [Hmim][Gly] solution were examined.
• A kinetic model of absorption CO2 into the [Hmim][Gly] solution was developed.
• Activation energy for the second order reaction rate constant was calculated.
• Absorption capacity reached about 0.45 mol CO2 per mol of [Hmim][Gly].

CO2 absorption performance in the [Hmim][Gly] solution was investigated in detail at 298, 303, 313, 323 K within the concentration range of 0.5–1.2 M under an atmospheric pressure by using a double stirred cell absorber with a planar gas–liquid interface. The density, viscosity and pH of the [Hmim][Gly] solution were obtained, and the solubility and diffusivity of CO2 in [Hmim][Gly] solution were calculated. To explore the regeneration property of the CO2-loaded solution, method under vacuum pressure was used by varying the regeneration temperature from 328 to 343 K and the regeneration time in the range of 30–120 min. The effect of regeneration cycles on regeneration efficiency was also determined. The kinetic results demonstrated that the reaction took place in a fast pseudo-first order regime. Hatta number Ha, the enhancement factor E, the overall reaction kinetic constant kov and the second-order rate constant k2 were obtained using the two-film model. At the absorption temperature of 303 K, the enhancement factor E   was linear with CIL1/2. The second-order reaction rate was determined as the following equation: k2=3.04×107exp(−3050/T)k2=3.04×107exp(−3050/T).