Density measurements and modelling of loaded and unloaded aqueous solutions of MDEA (N-methyldiethanolamine), DMEA (N,N-dimethylethanolamine), DEEA (diethylethanolamine) and MAPA (N-methyl-1,3-diaminopropane)

•Densities of unloaded and loaded amine aqueous solutions are measured and modelled.•Density for MDEA, DMEA, DEEA and MAPA aqueous solutions is measured.•A proportionality model is proposed for correlating loaded amine solutions densities.•A comparison with the Rackett model is done.•The Redlich–Kister type of model is used to correlate the unloaded solutions. In order to design absorption and desorption towers several properties of the chemical system must be accurately calculated using models based on experimental data. In the present work, the densities of aqueous solutions of MDEA (N-methyldiethanolamine), DMEA (N,N-dimethylethanolamine), DEEA (diethylethanolamine) and MAPA (N-methyl-1,3-diaminopropane), potential solvents for CO2 capture, are presented. The density of unloaded solutions is modelled by using the Redlich–Kister model with 3 parameters. An empirical proportionality model that correlates the density change due to CO2 loading to the amount of CO2 loaded is also presented. The proportionality model is able to adequately predict the density of loaded solutions with only two extra parameters. Densities for loaded and unloaded MEA (monoethanolamine) aqueous solutions were also correlated with data from literature by the presented models. A comparison between the performance of the Redlich–Kister, the proportionality model and the Rackett models is presented. It is shown that the Rackett model can be used to give a good estimate for the liquid densities. However, the accuracy is in general one order of magnitude lower than for the Redlich–Kister fit and the maximum absolute deviation can be 8 times higher than the one calculated with the proportionality model.