Article Cite This: J. Chem. Eng. Data XXXX, XXX, XXX-XXX
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Investigation on Temperature-Dependent Volumetric and Acoustical Properties of Homologous Series of Glycols in Aqueous Sorbitol Solutions Kirandeep Kaur,† Kailash C. Juglan,† and Harsh Kumar*,‡ †
Department of Physics, Lovely Professional University, Phagwara, Punjab 144402, India Department of Chemistry, Dr B R Ambedkar National Institute of Technology, Jalandhar, Punjab 144011, India
‡
S Supporting Information *
ABSTRACT: In the present study, the combination of volumetric and acoustical studies is used to investigate the interactions of ethylene glycol, diethylene glycol, and triethylene glycol with sorbitol as a function of temperature. Densities and ultrasonic velocities of ethylene, diethylene, and triethylene glycol in (0.00, 0.01, 0.03, 0.05) mol·kg−1 aqueous solutions of sorbitol have been measured at temperatures T = (288.15, 298.15, 308.15, 318.15) K and experimental pressure p = 0.1 MPa. With the help of density data, the apparent molar volume Vϕ, the partial molar volume Voϕ, and the partial molar volumes of transfer ΔVoϕ, from water to aqueous sorbitol solutions have been computed. The values for partial molar expansibility (∂V0ϕ/∂T)p and second order derivative (∂2V0ϕ/∂T2)p have also been determined. From ultrasonic velocity values, apparent molar isentropic compression Kϕ,s, partial molar isentropic compression Koϕ,s, and partial molar isentropic compression of transfer ΔKoϕ,s, are evaluated. The computed values of partial molar volumes of transfer and partial molar isentropic compression of transfer are used to determine the pair and triplet coefficients. The parameters thus obtained have been discussed in terms of solute−solute/solute−solvent interactions prevailing in the present ternary system along with the structure making/structure breaking tendency of glycols in aqueous sorbitol solutions.
1. INTRODUCTION The solvation of solute in various solvents or the mixing effect of chemical mixtures widely used in industry is difficult to know; therefore, an understanding of thermodynamic properties such as densities, ultrasonic velocities, apparent molar and partial apparent molar properties is of significant importance.1 During the formation of liquid mixtures, a change in molecular interactions occurs, and the difference in component packing becomes apparent.2,3 The volumetric and acoustic study of liquid mixtures facilitates the determination of thermodynamic properties which are highly sensitive to molecular interactions. The liquid mixtures containing glycols are extensively used in the cosmetic, pharmaceutical, biotechnological, and food industries.4−10 Ethylene glycols are the liquids which are miscible in water in the whole composition range, and due to their hygroscopic nature, are highly soluble in polar solvent owning H-bonding.11−13 These glycols are broadly used in the plastic industry where they are used in the preparation of polyethylene terephthalate which is used further to make plastic bottles for the pharmaceutical and food industry.14−18 Ethylene glycols (EGs) are solvents possessing oxy and hydroxyl groups in the same molecule due to which the formation of inter- and intramolecular hydrogen bonds between −O− and −OH groups has been observed.19 A considerable amount of work has already been published on densities and speeds of sound of EGs with water, ethers, alcohols, and amides,20−33 but to best © XXXX American Chemical Society
of our knowledge no data is available on the study of thermodynamic properties of glycols with sugar alcohols. Sugar alcohols are a kind of “low-digestible carbohydrate”, a group that comprises fiber and resistant starch. Sorbitol is one of the sugar alcohols, having six OH groups due to which hydrogen-bond formation occurs when the substance is dissolved with water. It is often used as a substitute to sugar in various diet foods (including soft drinks and ice cream), cough syrups, mints, and sugar-free chewing gum.34−36 To store these diet foods, various containers are used from the plastic industry where EGs play a major role; therefore, it is also important to study the interaction of sorbitol with EGs. Despite numerous applications of mixtures containing sorbital, much less work has been done on their thermodynamic study.37−39 Also thermo-acoustical properties of glycols have been studied with water, alcohols, amides, and ethers,40−44 but so far to best of our knowledge no data are available on densities and speeds of sound of mixtures of sorbitol and ethylene glycols. In the present study, we carry out a systematic study on the volumetric and acoustical properties of ethylene glycol (EG), diethylene glycol (DEG), and triethylene glycol (TEG) in aqueous sorbitol solutions at different temperatures T = Received: June 5, 2017 Accepted: October 9, 2017
A
DOI: 10.1021/acs.jced.7b00501 J. Chem. Eng. Data XXXX, XXX, XXX−XXX
Journal of Chemical & Engineering Data
Article
Table 1. Specifications of Chemical Samples
3. RESULTS AND DISCUSSION 3.1. Volumetric Properties. 3.1.1. Density. The experimental values of densities, ρ of solutions for EG, DEG and TEG in (0.00, 0.01, 0.03, 0.05) mol·kg−1 aqueous solutions of sorbitol were measured at temperatures T = (288.15, 298.15, 308.15, 318.15) K. The density values for all the liquid mixtures at different temperatures are attributed in Table 2. It is observed from Table 2 that at a particular concentration of sorbitol, the density values of the liquid mixtures are increasing with rise in concentration of glycol and decreasing with rise in temperature. The plots of experimental data and literature data46−56 of densities of (EG, DEG, TEG) + water are shown in Figures 1−3 and the plots of experimental and literature values57−59 for density and ultrasonic velocity of sorbitol + water are shown in Figures 4 and 5, respectively. It is noted from the figures that the experimental values follow the same trend as the literature values. 3.1.2. Apparent Molar Volume. The experimental density values are used to calculate apparent molar volumes (Vϕ) from the following equation:60
(288.15, 298.15, 308.15, 318.15) K and the experimental pressure of 0.1 MPa. The apparent molar and partial apparent molar properties have been derived from the density and ultrasonic velocity data which are discussed in terms of solute− solute and solute−solvent interactions.
2. EXPERIMENTAL SECTION 2.1. Materials. Ethylene glycol (EG) having a mass fraction purity ≥ 0.99 and triethylene glycol (TEG) with a mass fraction purity ≥ 0.98 were acquired from Loba Chemie Pvt. Ltd., India. Diethylene glycol with a mass fraction purity ≥ 0.985 was obtained from SD Fine Chem. Ltd., India. All the chemicals were used as received without further purification. They were stored in tightly sealed dark bottles to lessen absorption of atmospheric moisture. Before performing experimental measurements, the liquids were stored over molecular sieves to reduce the water content. Sorbitol having a mass fraction purity ≥ 0.99 was procured from Loba Chemie Pvt. Ltd., India. Before its use, sorbitol was dried in vacuum and stored in desiccators over P2O5 for at least 2 days. The details of the chemicals used in this study are reported in Table 1. 2.2. Apparatus and Procedure. Triply distilled water which has been freshly degassed with specific conductance
