Vapor–Liquid Equilibria, Excess Enthalpy, and Density of Aqueous γ‑Valerolactone Solutions.

Thermodynamic measurements
were made for the binary mixture of
water + γ-valerolactone (GVL) and for pure GVL to facilitate
the development of the technology of lignin removal from lignocellulosic
biomass (Fang, W.; Sixta, H. Advanced Biorefinery based
on the Fractionation of Biomass in γ - Valerolactone and Water. ChemSusChem 2015, 8, 73−76). The density
and vapor pressure of pure GVL as a function of temperature were measured
and correlated for a wide range of the temperatures and pressures.
Isothermal vapor–liquid equilibrium (VLE) data of the binary
mixture of water + GVL were measured at 350.2 K with a static total
pressure apparatus. Absence of an azeotrope was confirmed by circulation
still measurements with diluted GVL solutions. Excess molar enthalpy
(hE) of the mixture for the whole range
of mole fractions including infinite dilution was measured using a
SETARAM C80 calorimeter equipped with a flow mixing cell at 322.6
and 303.2 K. The VLE and hE data were
used for the optimization of UNIQUAC and NRTL activity coefficient
model parameters. The experimental results are compared herein with
those predicted by COSMO-RS and UNIFAC-Dortmund models. The water
+ GVL binary mixture shows positive deviation from Raoult’s
law.