PVTx properties of the binary 1-propanol + n-hexane mixtures in the critical and supercritical regions

Abstract

PρTx relationship of the binary 1-propanol+n-hexane mixture were measured. Measurements were concentrated in the immediate vicinity of the critical and supercritical regions in order to closely observe the features of the mixture critical curve behavior (critical phenomena in the 1-propanol+n-hexane mixture) and other derived thermodynamic properties. The measurements have been made over the temperature range from (403 to 573) K for liquid and vapor isochores between (92 and 564) kg·m−3 up to 61MPa using a high-temperature and high-pressure constant-volume piezometer. The combined expanded uncertainty of the density, ρ, pressure, P, temperature, T, and concentration, x, measurements at the 95% confidence level with a coverage factor of k=2 is estimated to be 0.15%, (0.02 to 0.05) %, 10mK, and 0.01 mole %, respectively. The critical curve data (TC−x), (PC−x), and (ρC−x), were extracted from the measured PρTx data. The extracted critical curve and direct measured P−x data along the critical isochore-isotherm were used to estimate the value of the Krichevskii parameter for the mixture when 1-propanol is solvent at the critical state. The measured PρTx data were used to calculate excess and partial molar volumes of n-hexane near the critical point of pure 1-propanol. The isomorphic thermodynamic behavior of the mixture have been studied on the bases of critical curve data and the critical amplitudes of the pure solvent (1-propanol).