Application potential of N-hexylpyridinium bromide for separation azeotrope: Thermodynamic properties measurements

A series of thermodynamic parameters of N-hexylpyridinium bromide ([Hpy]Br) ionic liquid (IL) were investigated by inverse gas chromatography (IGC) technique. These parameters included the Flory-Huggins interaction parameters (chi(12)), activity coefficients at infinite dilution (gamma(infinity)(12)), molar heat (enthalpy) of probe absorption in the [Hpy]Br (Delta H-1(S)), molar heat of mixing at infinite dilution between [Hpy]Br and probe (Delta H-1(infinity)), and Hildebrand solubility parameters (delta(2)). The isothermal vapor-liquid equilibrium (VLE) data of [Hpy]Br and solvents with good solubility at 353.15K were determined from chi(12) and correlated with the NRTL model. The potential of [Hpy]Br as an entrainer for separating benzene (1)/ethanol (2), benzene (1)/isopropanol (2), and benzene (1)/thiophene (2) azeotropic mixture by extractive distillation was explored using the y-x' diagram. Results showed that the azeotropy of three binary systems could be broken by adding [Hpy]Br and the reliability of thermodynamic analyses was verified. (C) 2022 Elsevier B.V. All rights reserved.