Volumetric behaviour of binary liquid systems composed of toluene, isooctane, and methyl tert-butyl ether at temperatures from (298.15 to 328.15) K
Introduction
Research activities of our laboratory comprise, among others, the systematic measurement of volumetric properties of different groups of organic compounds. Our present project is devoted to the systematic study of liquid systems modelling liquid engine fuels. After measuring (cyclohexane + alkane) at normal pressure and T = 298.15 K [1], (cyclohexane + nonane) at temperatures from (298.15 to 328.15) K and at pressures up to 40 MPa [2], (octane + benzene, or +toluene, or +1,3-xylene, or +1,3,5-trimethylbenzene) at temperatures between (298.15 and 328.15) K [3], and (octane + benzene) at temperatures from (298.15 to 328.15) K and at pressures up to 40 MPa [4], the binary and ternary systems containing methyl tert-butyl ether (MTBE) have been studied with the aim to decide what and how many ternary constants, in addition to the binary constants, are needed to fit the ternary data to Redlich–Kister equation within the error of experimental results. This measurement is also of practical importance with respect to use of MTBE as the liquid fuel antiknock additive.
The thorough literature search showed that there exist some limited binary data for these systems (for their detailed comparison with our results see Section 3). However, to be able to do the test, we needed more accurate and mutually consistent binary (and ternary) results. Not finding such data sets, we decided to measure the title binary systems as the first step.
The densities and excess volumes of the investigated liquids and their mixtures are required, for instance, for relating excess enthalpy and excess Gibbs free energy values. From a practical point of view, the data are useful for the design of mixing, storage, and process equipment. Last but not least, the measured results reflect interactions between the molecules of the mixtures studied and can serve for testing the theories of the liquid state.
Section snippets
Materials
The chemicals used in the experiments were the following products from Fluka: MTBE (methyl 1,1-dimethylethyl ether), puriss., g.c. mass fraction purity ⩾0.95, toluene, RdH, for chromatography, g.c. mass fraction purity ⩾0.995, isooctane (2,2,4-trimethylpentane), RdH puriss. p.a., g.c. mass fraction purity ⩾0.995. The substances were used without further purification and dried and stored over 0.4 nm molecular sieves. In order to check the purity of the substances, their density and refractive
Results and correlation
The results of the measurements of densities and sound velocities of the three binary systems are given in TABLE 2, TABLE 3, TABLE 4 together with the calculated values of and adiabatic compressibility κS and illustrated in FIGURE 1, FIGURE 2, FIGURE 3 for the temperature dependence of and in FIGURE 4, FIGURE 5, FIGURE 6 for the temperature dependence of κS. The adiabatic compressibility κS was calculated from the relationwhere u is the measured sound velocity. For fitting
Discussion
The values for (MTBE + toluene) are negative and considerably decreasing with increasing temperature. The other systems show positive with comparatively smaller temperature dependence. (Toluene + isooctane) exhibits decreasing with increasing temperature, (MTBE + isooctane) shows the same trend up to T = 328.15 K, then the opposite trend seems to start.
The deviations from ideal behaviour of the systems studied can be discussed in terms of intermolecular interactions as follows. In (toluene +
Acknowledgements
The authors acknowledge the partial support from the Grant Agency of the Czech Republic; the work has been carried out under Grants No. 104/06/0656 and No. 104/09/0666.
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2019, Journal of Molecular LiquidsExcess molar enthalpies of binary mixtures of n-octane, isooctane and cyclooctane with morpholine, 1,4-dioxane, piperidine, oxane, N-methyl piperidine and cyclohexane. Experimental results and DISQUAC modelling
2015, Journal of Molecular LiquidsCitation Excerpt :Their qualities were, however, verified by measuring their densities, at 308.15 K and atmospheric pressure, using an Anton Paar DMA 4500 vibrating-tube densimeter. The experimental density values were well compared to the available literature data [19–32], as it can be seen in Table 1. The excess molar enthalpies, HE, for the investigated binary mixtures, were measured at atmospheric pressure by means of a flow calorimeter (Model C80, SETARAM, France).
Volumetric behavior of the ternary system (methyl tert-butyl ether + methylbenzene + butan-1-ol) and its binary sub-system (methyl tert-butyl ether + butan-1-ol) within the temperature range (298.15 to 328.15) K
2015, Journal of Chemical ThermodynamicsCitation Excerpt :The real adiabatic compressibility (equation (3)) was calculated from the experimentally determined density and speed of sound. The two binary systems, namely (MTBE + toluene) [3] and (toluene + butan-1-ol) [4], have been discussed previously. The resulting curves of concentration dependence for the binary (MTBE + butan-1-ol) system were negative over the whole concentration and temperature ranges.