Determination of experimental excess molar properties for MTBE+1-propanol+octane

Summary Experimental excess molar enthalpies and densities have been measured for the ternary mixture x₁MTBE+x₂1-propanol+(1-x₁-x₂)octane and the involved binary mixtures at 298.15 K and atmospheric pressure. In addition, excess molar volumes were determined from the densities of the pure liquids and mixtures. A standard Calvet microcalorimeter was employed to determine the excess molar enthalpies. Densities were measured using a DMA 4500 Anton Paar densimeter. The UNIFAC group contribution model (in the versions of Larsen et al., and Gmehling et al.) has been used to estimate excess enthalpies values. Experimental data were also used to test several empirical expressions for estimating ternary properties from experimental binary results.     

Experimental excess molar volumes of the ternary mixture and comparisonwith several empirical methods

Experimental excess molar volumes for the ternary system {x₁MTBE+x₂1-propanol+(1–x₁–x₂)nonane} and the three involved binary mixtures have been determined at 298.15 K and atmospheric pressure. Excess molar volumes were determined from the densities of the pure liquids and mixtures, using a DMA 4500 Anton Paar densimeter. The ternary mixture shows maximum values around the binary mixture MTBE+nonane and minimum values for the mixture MTBE+propanol. The ternary contribution to the excess molar volume is negative, with the exception of a range located around the rich compositions of 1-propanol. Several empirical equations predicting ternary mixture properties from experimental binary mixtures have been applied.     

Surface tension,density, and speed of sound for the ternary mixture {diethyl carbonate + p-xylene + decane}

This paper reports the results of a new experimental study of thermophysical properties for the ternary mixture of {diethyl carbonate + p-xylene + decane}. Surface tension has been measured at 298.15 K and, density and speed of sound have been measured in the temperature range T = (288.15 to 308.15) K. Excess molar volumes, excess isentropic compressibilities, and surface tension deviations, have been calculated from experimental data. Surface tension deviations have been correlated with Cibulka equation and Nagata and Tamura equation was used for the other excess properties. Good accuracy has been obtained. These excess magnitudes are discussed qualitatively in terms of the nature and type of intermolecular interactions of the components involved.     

Study of static permittivity and density of the systems {(n-nonane + monoglyme or diglyme)} at various temperatures

Relative permittivity and density on mixing at atmospheric pressure and temperatures from (288.15 to 328.15) K have been measured over the whole composition range for {CH₃O(CH₂CH₂ O)_mCH₃ m = 1, 2 (also called monoglyme and diglyme) + n-nonane}. Excess permittivity and molar volume on mixing for the above systems have been calculated. The Redlich–Kister equation has been used to estimate the binary fitting parameters and standard deviations from the regression lines were calculated. The density and excess molar volume were fitted to a polynomial equation as a function of the mole fraction and temperature. The temperature dependences of derived magnitudes, ${\left(\frac{\mathrm{?}{V}_{\text{m}}^{\text{E}}}{\mathrm{?}T}\right)}_{P\text{,}x}$ and ${\left(\frac{\mathrm{?}{H}_{\text{m}}^{\text{E}}}{\mathrm{?}P}\right)}_{T\text{,}x}$, were computed, due to its importance in the study of specific molecular interactions. Different mixing rules have been applied to predict the permittivity of these mixtures and the results indicate that the predictions are better when the volume change on mixing is incorporated in calculations. In order to determine the dipolar moment of the glymes using Debye’s model at infinite dilution, their refraction index was measured. The values obtained agree with those in the literature for infinite dilution in hexane.     

Temperature dependence of volumetric behaviour for methyl tert-butylether+1-butanol system

Excess molar volumes and excess isoentropic compressibilities of methyl tert-butylether (MTBE)+1-butanol at 288.15, 293.15, 298.15, 303.15 and 308.15 K and atmospheric pressure have been studied. In order to analyse the temperature dependence of this mixture, isobaric expansibility a, (dV _m ^e dT) _P,xand (dH _m ^e dP ) _T,x, were computed by analytical differentiation of the density and excess molar volume fitting equations. Cubic equation of state (Soave-Redlich-Kwong) has been applied to excess molar volume correlation obtaining binary interaction parameters using different mixing rules. This revised version was published online in July 2006 with corrections to the Cover Date.     

Temperature dependence of the volumetric properties of binary mixtures containing oxaalkane +n-heptane

Excess molar volumes of mixtures of n-heptane + 2,5-dioxahexane and n-heptane + 2,5,8-trioxanonane were determined from density measurentents at 5, 15, 25 and 35°C. These results allowed the following mixing quantities to be reported in all range of concentrations: , (v ^E /T) _P and (h ^E /P) _T , at 25°C. The obtained values were then compared with the calculated values by using the Flory theory and the Nitta-Chao theory of liquid mixtures. The results are discussed in terms of order or disorder creation.     

Excess molar enthalpies of dichloropropane + <Emphasis Type="Italic">n</Emphasis>-alkane mixtures

We have determined the excess molar enthalpies H_\textm^\textE H_{\text{m}}^{\text{E}} at 298.15 K and normal atmospheric pressure for the binary mixtures containing dichloropropane and n-alkane [{xCH₂ClCHClCH₃ + (1−x) C _n H_2n+2 (n = 6, 8, 10, 12)} and {xCH₂ClCH₂CH₂Cl + (1−x) C _n H_2n+2 (n = 8, 10)}] using a Calvet microcalorimeter. The H_\textm^\textE H_{\text{m}}^{\text{E}} values for all the mixtures show endothermic behaviour for the whole composition range. The Redlich–Kister equation was used to correlated the experimental values. The experimental excess molar enthalpies were examined on basis of the DISQUAC group-contribution model and the UNIFAC group-contribution method using the version considered by Larsen et al. The experimental and calculated results are discussed in terms of molecular interactions and the proximity effect.     

Microcalorimetric study of the growth of <Emphasis Type="Italic">Enterococcus faecalis</Emphasis> in an enriched culture medium

Enterococcus faecalis is a Gram-positive bacteria, considered one of the most common causes of nosocomial infections. Bacterial cultures produce an exchange of energy as a result of the bacteria metabolisms. The rate of heat production is an adequate measure of the metabolic activity of the organisms and their constituent parts. Microorganisms produce small amounts of heat: 1–3 pW per cell. Although the heat produced by bacteria is very small, their exponential reproduction in a culture medium permits heat detection through microcalorimetry. In this study, we analyzed the microcalorimetric behavior of Enterococcus faecalis. A thermal Calvet microcalorimeter was used. The inside of the calorimeter contains two stainless steel cells (experimental and reference). Experiments were carried out at final concentrations of 10⁶,10⁵,10³, and 10 CFU/mL and a constant temperature of 309.65 K was maintained within the microcalorimeter. Recording the difference in calorific potential over time we obtained E. faecalis’s growth curves. Thermograms were analyzed mathematically allowing us to calculate the constant growth, generation time and the amount of heat exchanged over the culture time.     

Ternary mixture MTBE+1-pentanol+nonane at 298.15 K and atmospheric pressure

Densities at 298.15 K and atmospheric pressure have been measured, using a DMA 4500 Anton Paar densimeter, for the ternary mixture methyl tert-butyl ether (MTBE)+1-pentanol+nonane and for the involved binary mixture 1-pentanol+nonane. In addition, excess molar volumes were determined from the densities of the pure liquids and mixtures. Suitable fitting equations have been used in order to correlate adequately the excess molar volumes. Experimental data were also used to test several empirical expressions for estimating ternary properties from experimental binary results.     

Excess molar enthalpies of the ternary system MTBE+ethanol+octane

Excess molar enthalpies of the ternary mixture {x ₁ tert-butyl methyl ether (MTBE)+x ₂ ethanol+(1–x ₁–x ₂) octane} and the involved binary mixture {x ethanol+(1–x) octane} have been measured at 298.15 K and atmospheric pressure, over the whole composition range, using a Calvet microcalorimeter. The results were fitted by means of different variable degree polynomials.