Volumetric Properties of Aqueous Solutions of Ethylene Glycols in the Temperature Range of 293.15–318.15 K

Omer El-Amin Ahmed Adam,Ammar Hani Al-Dujaili,Akl M Awwad

doi:10.1155/2014/639813

Abstract

Densities of aqueous solutions of Ethylene glycol (EG), diethylene glycol (DEG), and triethylene glycol (TEG) were measured at temperatures from 293.15 to 318.15 K and molalities ranging from 0.0488 to 0.5288 mol·kg−1. Volumes of all investigated solutions at a definite temperature were linearly dependent on the solute molality; from this dependence the partial molar volumes at infinite dilution were determined for all solutes. It was found that the partial molar volumes at infinite dilution V-2,0 were concentration independent and slightly increase with increasing temperature. The partial molar volumes at infinite dilution V-2,0 or the limiting apparent molar volumes of ethylene glycols were fitted to a linear equation with the number of oxyethylene groups (n) in the solute molecule. From this equation a constant contribution of the terminal (OH) and the (CH2CH2O) groups to the volumetric properties was obtained. The thermal expansion coefficient (α1,2) for all investigated solutions was calculated at temperatures from 293.15 to 318.15 K. The thermal expansion coefficients for all solutes increase with increasing temperature and molality. Values of (α1,2) were higher than the value of the thermal expansion coefficient of the pure water.

Highlights

Mixing effects for thousands of chemical compounds and their mixtures used in industry are rather difficult to be known; knowledge of thermodynamic properties such as densities, as well as excess molar volumes, VE, partial molar volumes, and apparent molar volumes of organic mixtures at various temperatures, is of great importance
We report the density of binary mixtures containing ethylene glycol (EG), diethylene glycol (DEG), and triethylene glycol (TEG) with water at temperatures ranging between 298.15 and 318.15 K
The obtained results of the densities of all binary mixtures are plotted as a function of the molality of solution (m/mol⋅kg−1), (Figure 1)

Summary

Introduction

Mixing effects for thousands of chemical compounds and their mixtures used in industry are rather difficult to be known; knowledge of thermodynamic properties such as densities, as well as excess molar volumes, VE, partial molar volumes, and apparent molar volumes of organic mixtures at various temperatures, is of great importance. Analysis of multicomponent liquid mixtures in terms of mole fraction or molality and their thermodynamic and volumetric properties are important for the design of industrial processes. Ethylene glycols are very interesting solvents owing to the presence of the oxy and hydroxyl groups in the same molecule Due to this the formation of intra- and intermolecular hydrogen bonds between the –O– and –OH groups of the same or different molecules of ethylene glycols has been observed [9]. Despite their interesting characteristics and industrial importance, thermodynamic properties of mixtures containing ethylene glycols have not been studied extensively enough [10]. The experimental data have been used to calculate the partial molar volumes and thermal expansion coefficients

Experimental

Results and Discussion

Conclusions