Thermodynamics Research Center / ThermoML | Journal of Chemical and Engineering Data

ABSTRACT

The objective of this study was to determine the correlation equation between CO2 absorption capacity and measured electrical conductivity in CO2 absorption system using diethanolamine (DEA) as solvent based on various theoretical and experimental results. In addition, the capacity and various results of the system were quantified and compared to those with monoethanolamine (MEA) system reported in previous papers. DEA solvent at 4 M was confirmed to be the most suitable one for application in commercial process because its mole ratio of CO2 to amine value was approximately 0.5. The ionic conductivities of carbamic acid (R2NH2 +) and carbamate (R2NCOO-) were estimated to be 38.46 and 20.01 S*cm2*mol-1*z-1, respectively. They were smaller than those of their corresponding ions of the MEA system. The ionic activity coefficient of DEA system was also smaller than that of the MEA system. However, the sensitivity of CO2 absorption capacity to electrical conductivity measured in constant concentration solution of the DEA system was higher than that in the MEA system. These results were basically caused by differences in molecular size, mole ratio of water to all ions present (H2O/ions), and density of electron dispersion of molecules between the MEA system and the DEA system.