Experiment and model for the surface tension of carbonated MEA–MDEA aqueous solutions

Surface tensions of CO2 unloaded and CO2 loaded MEA–MDEA aqueous solutions were measured by using the BZY-1 surface tension meter, which employs the Wilhemy plate principle. For CO2 unloaded solutions, the temperatures ranged from 293.15 to 333.15 K, and the mass fractions of MEA (wMEA) and MDEA (wMDEA) respectively ranged from 0.05 to 0.20, and 0.05 to 0.45. For CO2 loaded solutions, the temperatures ranged from 293.15 to 323.15 K, and wMEA and wMDEA respectively ranged from 0.05 to 0.10 and 0.30 to 0.45. The uncertainty of the surface tensions is ±0.1 mN m−1. A model was proposed to correlate the surface tensions of both CO2 loaded and CO2 unloaded solutions. For CO2 unloaded MEA–MDEA solutions, with 3 adjustable parameters as input, the average relative deviation (ARD) between experiments and calculations is 1.63%. For CO2 loaded MEA–MDEA solutions, with 5 adjustable parameters as input, ARD is 1.76%. The temperature, mass fractions of amines and CO2 loading dependence of the surface tensions were demonstrated on the basis of experiments and calculations.