Carbon Dioxide Absorption into Aqueous Potassium Salt Solutions of Arginine for Post-Combustion Capture

The mass transfer and kinetics of CO2 absorption into aqueous potassium argininate (ArgK) solutions were investigated using a wetted-wall column at concentrations ranging from 0.26 to 1.23 M and temperatures from 298 to 333 K. Absorption rates of CO2 were compared by the absorption flux and a fall-in-pressure method among basic amino acid salts (AAS) and two amine standards for capture technology. Results showed that ArgK has comparable kinetics toward CO2 with the standard monoethanolamine (MEA) but lower kinetics than piperazine (PZ). The kinetic results were interpreted using two models based on zwitterion mechanism and termolecular mechanism for the reactive absorption of CO2. It was found that the partial reaction orders vary from 1.25 to 1.60 with respect to ArgK. Under the pseudo-first-order regime, the overall reaction rate constants were obtained and the individual reaction rate constants in these models were derived. The calculated values from two models agree well with the experimental data within 7.5% AAD.