Propriedades volumétricas, viscosimétricas, acústicas e espectroscópicas de soluções líquidas binárias contendo gama-valerolactona (GVL) e álcoois

Substances derived from biomass have called attention, once these compounds belong to the group of renewable solvents, whose physicochemical properties present great potential for applications in several areas of science and industry, namely in biorefineries. Therefore, thermodynamic properties of systems containing such liquids is of practical interest, because experimental data can be used in modeling in order to improve processes or yet to develop and verify new models and solution theories, which have shown their complexity. The present project aims at studying excess thermodynamic properties, that quantify the real solution deviation in comparison to the ideal one, and spectroscopic analyses of binary liquid systems constituted of gamma-valerolactone (GVL) + alcohols (ethanol, 1-propanol, 1-butanol or 1- pentanol). For this purpose, original values of density, speed of sound and dynamic viscosity were determined for these solutions in the whole composition range and in temperatures T = (293.15 – 313.15) K under ambient pressure (92.3 kPa). From these experimental results, it was possible to calculate volumetric properties such as excess molar volume (Vm E ), acoustic property as deviation in isentropic compressibility (??S), viscometric as deviation in viscosity (??) and excess Gibbs energy of activation of viscous flow (?G *E). These properties resulted in negative values at all conditions, except for Vm E , which was totally negative only in ethanol-GVL system. To complete the thermodynamic discussion, both nuclear magnetic resonance (1H-NMR and 13C-NMR) and infrared (ATR-FTIR) spectroscopies have been performed, whose spectra proved the existence of weak hydrogen bondings between GVLalcohol

Thermo-physical properties and activity coefficients at infinite dilution for ionic liquid systems at several temperatures

The thermodynamic properties of mixtures involving ionic liquids (ILs) with organic acid (acetic acid or propanoic acid) or acetonitrile at different temperatures were determined. The ILs used were imidazolium-based: 1-ethyl-3-methylimidazolium ethyl sulphate [EMIM]+[EtSO4]-, 1-butyl- 3-methylimidazolium thiocyanate [BMIM]+[SCN]- and 1-butyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide ([BMIM]+[Tf2N]-. The ternary excess molar volume (V E ), isentropic compressibility (ks) and deviation in isentropic compressibility ( ks123 ) were determined for four ternary liquid mixtures of {[EMIM]+[EtSO4]- or [BMIM]+[SCN]− + acetic or propionic acid + acetonitrile} at different temperatures (293.15, 298.15, 303.15, 308.15 and 313.15) K and at a pressure of 0.1 MPa with aid of the experimental density (ρ), speed of sound (u) data. The calculated data were correlated by using the Cibulka equation with the help of Redlich–Kister parameters obtained from fitting the Redlich–Kister equation for the corresponding binary systems. Furthermore, the density and speed of sound were also measured for eight corresponding binary systems at the same experimental conditions. The binary excess molar volume, isentropic compressibility and deviation in isentropic compressibility were also calculated for measured systems and fitted to the Redlich–Kister equation to obtain the Redlich–Kister parameters as well as to check the accuracy of measured data which were used to correlated experimental data using Cibulka equation. These results were discussed, in terms of how the sign and magnitude of thermodynamic functions were influenced by the addition of a third component to liquid systems. Also, the possible molecular and pair-wise interactions between component molecules and the effect of temperature on the thermophysical and thermodynamic properties were predicted. In addition, the work focussed on application of ([BMIM]+[Tf2N]-) ionic liquid for the separations of (alkane/aromatic), (alkane/alk-1-ene), (cycloalkane/aromatic) and (water/alkan-1-ol) using gas- liquid chromatography (GLC) technique. The activity coefficients at infinite dilution, , for 31 organic solutes (alkanes, cycloalkanes, alkenes, alkynes, aromatics, alkanol and ketones) and water in ionic liquid were measured at temperatures of (323.15, 333.15, 343.15, 353.15 and 363.15) K. Stationary phase loadings of (42.83 and 68.66) % by mass were used to ensure repeatability of E , measurements. Partial molar excess enthalpies at infinite dilution, H1 , were also determined. The selectivities, S , and capacities, k , were determined for the above separations. The separating ij j ability of the investigated ionic liquid was compared with previously investigated ionic liquids and industrial solvents such as sulfolane, n-methyl-2-pyrrolidine (NMP) and n-formylmorpholine (NFM). The results obtained suggested that in general, the [BMIM]+[Tf2N]− had outperformed the conventional solvents such as sulfolane, NMP and NFM in terms of selectivity, while the [BMIM][Tf2N] had in general, performed better overall when the performance index was used for comparison.

Acoustic and Volumetric Properties of Mixture of (N,N-Dimethylacetamide + Ethyl Acrylate) with 1-Butanol or iso-Butanol or t-Butanol at 308.15 K

Densities, ρ, and ultrasonic speeds, u of mixtures of 1-butanol or iso-butanol or t-butanol with equimolar mixture of (N,N-dimethylacetamide + Ethyl acrylate) over the entire composition range have been measured at T=308.15 K. Using the experimental results, deviation in ultrasonic speed, Δu, deviation in isentropic compressibility, Δks, excess molar volume, VmE, excess intermolecular free length, LfE, and excess acoustic impedance, ZE, have been calculated. The variation of these properties with composition of the mixtures has been discussed in terms of molecular interactions in these mixtures. The deviation/excess properties have been fitted to Redlich-Kister type polynomial and the corresponding standard deviations have been calculated. Negative values of VmE, Δks, and LfE and positive values of Δu, and ZE are observed over the entire composition range. The observed negative and positive values of deviation/excess properties are attributed to the strong interactions between the unlike molecules of the mixtures. Further theoretical values of sound velocity in the mixtures have been evaluated using various theories and compared with experimental sound velocities to verify the applicability of such theories to the systems studied. Theoretical ultrasonic velocity data has been used to study molecular interactions in the systems investigated.

Thermodynamic and transport properties of binary liquid systems

Densities, viscosities, and sound velocities were determined for the system o-chlorophenol + acetone and o-chlorophenol + ethyl methyl ketone at 25 °C. From the experimental results, the deviation in isentropic compressibility KS, excess molar volume VE, excess viscosity ηE, and excess molar free energy of activation of flow G*E were calculated. The deviations from ideality of the thermodynamic and transport functions are explained on the basis of molecular interactions between the components of the mixture.

Excess Volumes and Isentropic Compressibilities of Binary Mixtures of Butylamine and Cyclic Ketones

Excess volumes and isentropic compressibilities for the binary mixtures of cyclohexanone, cylopentanone and 2-methylcyclohexanone with butylamine were determined at 303�15 and 313�15 K. Excess volumes of the three mixtures are negative over the whole range of compositions at both the temperatures. Deviations in isentropic compressibility are also negative in all the three mixtures. The results are ascribed to strong hydrogen bonding between unlike molecules. The results also suggest that cyclization decreases both √E and the deviation in isentropic compressibility.

Excess Volumes and Isentropic Compressibilities of Binary Mixtures of an Alcohol and Isobutyl Methyl Ketone

Excess volumes and isentropic compressibilities for the binary mixtures of propan-1-ol, butan-1-ol, pentan-1-ol, hexan-1-ol with isobutyl methyl ketone were determined at 303.15 and 313.15 K. Excess volumes of the four mixtures are negative over the whole range of compositions at both the temperatures. Deviations in isentropic compressibility are also negative in all cases, except for propan-1-ol + isobutyl methyl ketone. In this system, the deviation in isentropic compressibility shows an inversion in sign at 303.15 K.