Representation of CO2 and H2S Absorption by Aqueous Solutions of Diethanolamine Using an Electrolyte Equation of State

The electrolyte equation of state published in 1993 by Fürst and Renon ( AIChE J . 1993, 39, 335) has been applied to the representation of CO 2 and H 2 S solubility in diethaloamine (DEA) aqueous solutions. This equation of state extends the classical Redlich−Kwong−Soave equation of state associated with a Wong−Sandler mixing rule to the case of systems containing ions. The study of binary systems allowed us to determine the parameters of the nonelectrolyte part of the equation of state. The ionic parameters have been fitted from experimental solubility data covering a wide range of experimental conditions (temperature range, 25−100 °C; amine concentration, from 0.5 to 3.5 M; loadings up to 2.34 mol CO 2 /mol amine ). With the assumption used in previous applications of our model to various electrolyte systems, the adjusted ionic parameters are interaction ones involving protonated amine and anions as well as molecular compounds. The resulting model represents experimental data with deviations consistent with the experimental ones and close to the deviations obtained in previous studies.