Kinetic study of carbon dioxide absorption with aqueous potassium carbonate promoted by arginine

The absorption of carbon dioxide (CO2) into aqueous 35 wt.% equivalent potassium carbonate (K2CO3) solution was performed using a wetted wall column at temperatures from 313 K to 343 K. Effect of arginine concentrations on absorption rates of CO2 into carbonate solutions was investigated and the second-order rate constant k1 was obtained using two-film model. Preliminary screening results showed that arginine was an effective promoter in aqueous K2CO3 solution for CO2 capture. The reaction of CO2 with arginine is described using zwitterionic mechanism. The overall reaction kinetic constant kov strongly increased with the increase of arginine concentration and absorption temperature under the investigated range. Based on the pseudo-first-order regime, the reaction rate parameters were obtained from the kinetic measurements and k1 was determined as 33,641 and 85,367 L mol−1 s−1 at 315 K and 325 K, respectively with activation energy of 71.9 kJ mol−1. The overall reaction rate for CO2 absorption into promoted K2CO3 were described as the following equation: -rCO2=2.58×1016exp-8645TCArg+4.32×1013exp-6666TCOH-CCO2.

► Arginine is an effective promoter of CO2 absorption in aqueous K2CO3 solution.
► Absorption rate increased with increase of arginine concentration and temperature.
► The second-order rate constant k1 was obtained using two-film model.
► The overall absorption rate of CO2 into promoted K2CO3 was described.