Vapor–Liquid Equilibrium, Densities, and Interfacial Tensions of the System Ethanol + Tetrahydro-2H-pyran

Abstract

Isobaric vapor−liquid equilibrium (VLE) data have been measured for the binary system ethanol + tetrahydro-2H-pyran at (50, 75, and 94) kPa and over the temperature range (331 to 358) K using a vapor−liquid equilibrium still with circulation of both phases. Mixing volumes were also determined at 298.15 K and atmospheric pressure with a vibrating tube densimeter, while a maximum differential bubble pressure tensiometer was used to measure atmospheric interfacial tensions at 303.15 K. According to experimental results, the mixture exhibits positive deviation from ideal behavior, and minimum boiling point azeotropy is present at mid-range concentrations (0.55 < x 1 Az < 0.67). VLE measurements show also that the azeotropic mole fraction impoverishes in ethanol as pressure (or temperature) increases. The mixing volumes of the mixture evolve from positive to negative deviations as the concentration of ethanol increases. Finally, it is experimentally observed that the interfacial tensions exhibit positive deviations from the linear behavior. The VLE data of the binary mixture satisfy Fredenlund's consistency test and were well-correlated by the Wohl, nonrandom two-liquid (NRTL), Wilson, and universal quasichemical (UNIQUAC) equations for all of the measured isobars. The mixing volumes and interfacial tensions, in turn, were satisfactorily correlated using the Redlich−Kister equation.