The speciation reactions that take place in mixtures of water, carbon dioxide (CO2), and alka-
nolamines make the modelling of the chemical and
uid-phase equilibria of these systems chal-
lenging. We demonstrate for the rst time that the statistical associating
uid theory (SAFT),
formulated within a group-contribution (GC) framework based on transferable intermolecular
square-well (SW) potentials (SAFT-
SW) can be used to model successfully such complex
reacting systems. The chemical reactions in these mixtures are described via a physical associ-
ation model. The concept of second-order groups is introduced in the SAFT-
SW approach in
order to deal with the multifunctional nature of the alkanolamines. In developing the models,
several compounds including ethylamine, propylamine, ethanol, propanol, 2-aminoethanol and
3-amino-1-propanol are considered. We present calculations and predictions of the
uid-phase
behaviour of these compounds and a number of their aqueous mixtures with and without CO2.
The group-contribution nature of the models can be used to predict the absorption of carbon
dioxide in aqueous solutions of 5-amino-1-pentanol and 6-amino-1-hexanol. The proposed pre-
dictive approach offers a robust platform for the identi cation of new solvents and mixtures
that are viable candidates for CO2 absorption, thereby guiding experimental studies.