Experimental study on the calorimetric data of 2-butoxyethanol with aliphatic alcohols (C1–C4) and correlation with the Wilson, NRTL and UNIQUAC models at T = 298 K

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Highlights

Abstract

Excess molar enthalpies, HmE of binary mixtures of 2-butoxyethanol with methanol, ethanol, propan-1-ol, propan-2-ol, butan-1-ol and butan-2-ol were calculated from calorimetric data at T = 298 K and ambient pressure (81.5 kPa). Calorimetric measurements were performed with employing a Parr 1455 solution calorimeter in an isolated room. All the binary mixtures showed endothermic behavior except 2-butoxyethanol + methanol mixture which showed exothermic behavior over the entire range of compositions. The experimental data were then used to calculate excess partial molar enthalpies, HiE and excess partial molar enthalpies at infinite dilution, HiE,. The maximum HmE values were observed about 0.45–0.5 mol fraction of 2-butoxyethanol. HmE increases as the length and the branch chains of the alcohols increase. Finally, the experimental results were correlated by using the Redlich–Kister equation and three thermodynamic models (Wilson, NRTL, and UNIQUAC) based on the local composition theory.

Introduction

Thermodynamic properties are special parameters for investigation and interpretation of chemical reactions and other solution processes [1]. Excess thermodynamic properties of 2-alkoxyethanols with alcohols provide useful information about the structure, intermolecular interactions, as well as macroscopic behavior of the components in the mixtures. These data are needed in many engineering design processes including liquid-liquid extraction, distillation, separation, in petrochemical and pharmaceutical industries. 2-Alkoxyethanols are a very important category of industrial solvents. In these substances, hydrogen bonds playa very fundamental role in chemical, physical and biological processes [2], [3], [4], [5].

2-Butoxyethanol falls within the category of glycol ethers and consists of two components, i.e. an alcohol and ether, which forminter- and intramolecular hydrogen bonds. This polar solvent is notable. This material is a solvent for paints and surface coatings, as well as cleaning products and ink. Other applications of this solvent include hydraulic brake fluids, nitrocellulose resins, dry-cleaning compounds, rust-removing liquids, varnish removers, diesel fuels, cosmetic products such as hair dyes, nail polishes, nail polish removers and skin cleansers, as well as pharmaceutical industry [6], [7], [8].

Binary mixtures of 2-alkoxyethanols and alcohols represent deviations from ideal behavior.

A number of studies have been so far performed on the excess molar volume, deviation of speed of sound, deviation in viscosity and FT-IR and 1H-NMR of binary mixtures of 2-alkoxyethanol with alcohols [9], [10], [11], [12], [13]. According to our recent literature survey, experimental values of the excess molar enthalpy of 2-butoxyethanol with butan-1-ol have been reported [13].

In this study, excess molar enthalpies, HmE of binary mixtures of 2-butoxyethanol with methanol, ethanol, propan-1-ol, propan-2-ol, butan-1-ol and butan-2-ol were calculated from calorimetric data at T = 298 K and ambient pressure (81.5 kPa). Also excess partial molar enthalpies, HiE and excess partial molar enthalpies at infinite dilution, HiE, were calculated from experimental data. The experimental results were correlated by using the Redlich–Kister equation and three thermodynamic models (Wilson, NRTL, and UNIQUAC) based on the local composition theory.

Section snippets

Materials

2-Butoxyethanol, methanol, ethanol, propan-1-ol, propan-2-ol, butan-1-ol and butan-2-ol (RS) were purchased from Merck with a mass fraction higher than 99%. The purity grades of the pure component are reported in Table 1. The water content of propan-1-ol, propan-2-ol and butan-2-ol as determined by Karl Fischer titration were less than 3.2 ppm. Substances were used without further purifications. The experimental values of density, ρ and refractive index, nD25 of pure components at T = 298.15 K were

Experimental

From calorimetric data, HmE values were calculated for six binary mixtures of 2-butoxyethanol + (methanol,+ethanol,+propan-1-ol,+propan-2-ol,+butan-1-ol,+butan-2-ol) at 298 K. The results are given in Table 2 and are graphically represented in Fig. 1 as a function of mole fraction x1 of 2-butoxyethanol. As can be seen from Table 2 and Fig. 1, HmE values increase systematically for ethanol, propan-1-ol, butan-1-ol, propan-2-ol and butan-2-ol with 2-butoxyethanol. Also HmE values decrease for methanol

Conclusions

Excess molar enthalpies, HmE of binary mixtures of 2-butoxyethanol with methanol, ethanol, propan-1-ol, propan-2-ol, butan-1-ol and butan-2-ol were calculated from calorimetric data at T = 298 K and ambient pressure (81.5 kPa). HmE values are positive for all binary mixtures of 2-butoxyethanol with alcohols (C1–C4) except 2-butoxyethanol + methanol mixture, which has a negative HmE value over the whole composition range at T = 298 K. Also, excess partial molar enthalpies, HiE and excess partial molar

Acknowledgment

The authors would like to thank Bu-Ali Sina University for providing the necessary facilities to carry out the research.

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