Excess molar volumes and excess molar enthalpies of the binary mixtures of 1,2-dichloropropane with di- and triethylene glycol mono-alkyl ethers at T = 298.15 K

Abstract

The excess molar volumes V m E and excess molar enthalpies H m E at T = 298.15 K and atmospheric pressure for the binary systems of 1,2-dichloropropane (1,2-DCP) with di- and triethylene glycol mono-alkyl ethers have been determined by measuring density and heat flux, respectively. The density has been measured by using a digital vibrating-tube densimeter, whereas heat flux measurements have been carried out by using an isothermal calorimeter with a flow-mixing cell. The diethylene glycol mono-alkyl ethers are 2-(2-alkoxyethoxy)ethanols: diethylene glycol mono-propyl ether (DEGMPE), diethylene glycol mono-butyl ether (DEGMBE), and the triethylene glycol mono-alkyl ethers are 2-(2-(2-alkoxyethoxy)ethoxy)ethanols: triethylene glycol mono-methyl ether (TEGMME), triethylene glycol mono-ethyl ether (TEGMEE), and triethylene glycol mono-butyl ether(TEGMBE). It was found that both V m E and H m E values of the binary mixtures are negative over the whole composition range except for the mixture with very high mole fraction of 1,2-DCP( x 1) in both DEGMPE and DEGMBE. In the case of 2-(2-(2-alkoxyethoxy)ethoxy)ethanols, the negative values of V m E and H m E continue to increase with an increase of the alkyl chain length of these alkoxyethanols. The minimum values of V m E shift from −0.1939 cm 3 mol −1 for the mixture with DEGMPE to −0.40 cm 3 mol −1 for the mixture with TEGMBE at x 1 = 0.40–0.50. Also, the minimum negative values of H m E have been shown ranging from −472.9 J mol −1 (DEGMBE) to −800.5 J mol −1 (TEGMBE) at x 1 = 0.40–0.50. The experimental results of both H m E and V m E were fitted to the Redlich–Kister equation. The experimental H m E data were also fitted to three local-composition models (Wilson, NRTL, and UNIQUAC). It was found that among these three models, the NRTL equation provides the most appropriate correlating result.