Equilibrium solubility of carbon dioxide in N-methyldiethanolamine + piperazine aqueous solution: Experimental measurement and prediction

• New experimental data for solubility of CO2 in MDEA + PZ + H2O system are reported.
• A new model is used for prediction of the experimental data.
• There are very good agreements between experimental data and model predictions.

New experimental data for equilibrium solubility of carbon dioxide in aqueous solutions of N-methyldiethanolamine (MDEA) and piperazine (PZ) are reported for temperature range of 363–423 K and pressure range of 26.3–204.3 kPa. The measured data in combination with the data collected from literature are used to modify Deshmukh–Mather model for prediction of the solubility of carbon dioxide in MDEA + PZ solutions. In this model, a modified extended Debye–Hückel expression for electrolyte solutions is used for the calculation of activity coefficients. More than 300 data points in a wide range of temperatures, pressures and concentrations are used to optimize the interaction parameters for the studied system. Genetic Algorithm minimization technique is used for this optimization process. The gas-phase fugacity coefficients are also included and are calculated using Peng–Robinson equation of state. The predictions of the proposed model are compared with the experimental data reported by Liu et al. The results show a very good agreement between experimental data and model predictions.