VLE of CO2 in aqueous potassium salt of L-phenylalanine: Experimental data and modeling using modified Kent-Eisenberg model

In this study, vapor-liquid equilibrium (VLE) of CO2 in aqueous potassium salt of l-phenylalanine (K-Phe) was investigated. A high pressure solubility cell was used to measure the solubility of CO2 in aqueous solution of (10, 20 and 25) wt% K-Phe at 303.15, 313.15 and 333.15 K over a CO2 pressure range of 200-2500 kPa. Equilibrium CO2 solubility was defined in terms of CO2 loading (mole CO2/mole of amine). The effect of temperature, concentration and equilibrium CO2 pressure on CO2 loading was discussed. Experimental CO2 loading data in aqueous K-Phe solutions show that the solvent has good potential for CO2 capture systems. Also, a modified Kent-Eisenberg model was used to correlate the experimental CO2 solubility data and carbamate hydrolysis and amine deprotonation equilibrium constants were regressed as a function of temperature, concentration and equilibrium CO2 pressure. An average absolute deviation of 7.70% between experimental and predicted data indicated the good prediction capability of the applied thermodynamic model.