Quaternary liquid-liquid equilibria measurements and NRTL modelling for the (Water + Ethanol + 2-Propanol + 2,2,4-Trimethylpentane) system at 298.2K to 328.2K

Abstract

In this work, the influence of a second alcohol on the phase behaviour of (water + alcohol + entrainer) systems was investigated by measuring Liquid-Liquid Equilibrium (LLE) data for the quaternary system of (water + ethanol + 2-propanol + isooctane) under isobaric (0.1 MPa) conditions. Data were measured at three ethanol: 2-propanol ratios to characterise the quaternary system behaviour, and for the constituent ternary (water + ethanol + isooctane) and (water + 2-propanol + isooctane) systems at 298.2 K. The measured quaternary data exhibit an evolution in phase behaviour between the constituent ternary systems in both the miscibility and total alcohol distribution between the aqueous and organic phases. The individual alcohol behaviour highlights the differing intermolecular interactions occurring in the systems, resulting in an increased recovery of ethanol to the organic phase and 2-propanol to the aqueous phase in the quaternary system. Further, the influence of temperature on the quaternary system's phase behaviour was investigated by measuring the quaternary system's data at four temperatures (298.2 K, 308.22 K, 318.2 K, and 328.2 K).The ternary (water + alcohol + entrainer) LLE literature and experimental data were correlated well using the Non-Random Two Liquid (NRTL) activity coefficient model with binary interaction parameters (BIPs) incorporating linear temperature dependence. These BIPs acceptably predicted the quaternary system's total alcohol behaviour, but only qualitatively captured the correct individual alcohol behaviour.