Thermodynamic modeling of binary mixtures of ethylenediamine with water, methanol, ethanol, and 2-propanol by association theory.

Abstract

Association theories by statistical associating fluid theory (SAFT) and cubic plus association (CPA) equation of states (EoS) have effectively handled various thermodynamic purposes thus far; they consider hydrogen bonding effects in associating compounds (those with hydrogen bonds such as water and alcohols) in a proper way. The objective of this work is to thermodynamically undertake the study of ethylenediamine (EDA)-water, EDA-methanol, EDA-ethanol, and EDA-2-propanol binary mixtures in a manner to be useful for designing separation processes by CPA EoS. Accordingly, CPA EoS was applied to model vapor-liquid equilibrium (VLE) of several practical binary mixtures including EDA-water, EDA-methanol, EDA-ethanol, and EDA-2-propanol. It should be noted that the aforementioned mixtures are being studied by CPA EoS for the first time and necessary details are presented; two different association schemes (different situations for creating hydrogen bonds), 2B and 4C schemes, were considered for EDA. Water and studied alcohols were also modeled by 4C and 2B schemes, respectively. Moreover, the capability of two different combining rules (Elliot and CR-1) was evaluated. The azeotrope point available in the phase diagram of EDA-water system was correctly identified by CPA EoS. Furthermore, the liquid phase density of EDA-water was satisfactorily predicted by CPA EoS. It has also a high level of accuracy in VLE modeling of EDA-methanol, EDA-ethanol, and EDA-2-propanol mixtures. In the end, according to all provided results, it can be said that CPA EoS along with all required parameters obtained in this study is capable of describing thermodynamic behavior of studied mixtures.