Quinary Mutual Diffusion Coefficients of Aqueous Mannitol + Glycine + Urea + KCl and Aqueous Tetrabutylammonium Chloride + LiCl + KCl + HCl Solutions Measured by Taylor Dispersion

Taylor dispersion is widely used to measure binary mutual diffusion. Studies of three- and four-component solutions show that the dispersion method is also well suited for multicomponent diffusion measurements, including cross-coefficients for coupled diffusion. Numerical procedures are reported here to calculate mutual diffusion coefficients from dispersion profiles measured for solutions of any number of components. The proposed analysis is used to measure the sixteen quinary mutual diffusion coefficients of five-component aqueous mannitol + glycine + urea + KCl solutions and aqueous NBu₄Cl + LiCl + KCl + HCl solutions. Mannitol, glycine, urea and KCl interact weakly at the low solute concentrations used (0.010 mol·dm^?3). The diffusion coefficients of this system are compared with pseudo-binary predictions. Strong coupling of the NBu₄Cl, LiCl, KCl and HCl fluxes is interpreted by using ionic conductivities and Nernst equations to calculate limiting quinary diffusion coefficients for mixed electrolytes that interact by the electric field generated by ion concentration gradients.     

Vapor–liquid equilibrium of binary mixtures of trichloroethylene with 1-pentanol, 2-methyl-1-butanol and 3-methyl-1-butanol at 100 kPa

Isobaric vapor–liquid equilibria (VLE) have been obtained for the systems trichloroethylene+1-pentanol, trichloroethylene+2-methyl-1-butanol and trichloroethylene+3-methyl-1-butanol at 100 kPa using a dynamic still. The experimental error in temperature is ±0.1 K, in pressure ±0.1 kPa, and in the liquid and vapor mole fraction ±0.001. The three systems satisfy the point-to-point thermodynamic consistency test. All the systems show positive deviations from ideality. The data have been correlated with the Margules, van Laar, Wilson, NRTL and UNIQUAC equations.     

Thermodynamic properties of N,N-dimethylformamide + water

The excess viscosities, η^E, and excess energy of activation (ΔΕ_η)^Ε of dynamic viscosity have been investigated by using dynamic viscosity measurements for N,N-dimethylformamide + water (DMFW) mixtures over the entire range of mole fractions at five different temperatures. The results were also fitted with the Redlich–Kister equation. This system exhibited very large positive values of η^E and (ΔΕ_η)^Ε due to the increased dipole–dipole interactions and correlation length between unlike molecules. The activation parameters ΔΗ_σ and ΔS_σ have been also calculated, and they show that the critical region has an important effect on the dynamic viscosity properties. The results obtained are discussed from the viewpoint of the existence of interactions between the components.     

Influence of inorganic salts on the liquid–liquid equilibrium of water + furfuryl alcohol + cyclopentanone system at 298.15 K

Influence of inorganic salts on the system of liquid phase equilibrium of water + furfuryl alcohol + cyclopentanone at 298.2 K was studied. Different salt concentrations (0, 1 and 2 wt%) and the type of salt (LiCl, NaCl, KCl, and RbCl) were investigated. The results showed that the two-phase region of the ternary system enlarged by addition of salt. NRTL model was applied, and good correlation between the experimental data and the model was achieved as confirmed by the low rmsd values.     

Modelling of the NO + CO reaction over inhomogeneous surfaces

A phenomenological model of \(\mathrm {CO}\) oxidation with \(\mathrm {NO}\) reaction proceeding over composite (supported) catalysts is proposed and solved numerically using the finite difference method. The model is based on the coupled system of PDEs subject to nonclassical conjugate conditions at the catalyst-support interface and includes: the bulk diffusion of reactants from a bounded vessel towards the catalyst surface and the bulk one of the reaction products from the surface into the same vessel, adsorption and desorption of particles of reactants, and surface diffusion of adsorbed molecules. The readsorption of the reaction product N\(_2\)O is also taken into account. The influence of the rate constants of the adsorbed particle jumping via the catalyst-support interface and reaction rate constants on the surface reactivity is investigated. It is shown that the turnover rates of the CO and NO into products N\(_2\)O, CO\(_2\), and N\(_2\) are nonmonotonic time functions and depending on values of the kinetic parameters may possess one or two maxima. The N\(_2\)O readsorption in case of the existence of two maxima essentially increases the turnover rates and extends the duration of their high values. The mechanism and conditions for arising of the second maximum is discussed. It is also shown that the variation of the particle jumping rate constants influences differently the size of the jump discontinuity of concentrations of different adsorbates at the catalyst-support interface.     

Excess enthalpies of binary mixtures of butylamines + propanols at 298.15 K

The molar excess enthalpies of eight systems of butylamines + propanols were determined at 298.15 K using a twin-microcalorimeter. All excess enthalpies were exothermic and large. An equilibrium constant K ₁ expressed in terms of mole fractions and standard thermodynamic properties of formation (Δ_f H, Δ_f G, Δ_f S) of 1:1 complex were evaluated by ideal mixtures of monomeric molecules and their associated complexes. Concentration dependence of the FT-Raman spectrum showed systematic changes of bands. Spectroscopic considerations based on this and ab initio calculations on molecules were performed at the Mp2/6-311G(d,p) level of theory. Interaction energies between butylamine and propanol were calculated by the supermolecular and NBO methods. The results were discussed with previous results to clarify the steric and positional effect of the amino and hydroxyl group.     

Solubility of minoxidil in binary mixture of ethanol + water at various temperatures

ABSTRACT

The solubility of minoxidil in the aqueous binary mixtures of ethanol at different temperature are investigated and the obtained solubility data are fitted by using some cosolvency models including van’t Hoff equation, Yalkowsky model, Jouyban–Acree model and Jouyban–Acree–van’t Hoff model. The mean relative deviations (MRD%) are used to illustrate the models performance. Moreover, the apparent entropy, enthalpy, and Gibbs free energy of minoxidil dissolution process in the investigated solvent mixtures are computed using van’t Hoff and Gibbs equations. Finally, by means of the inverse Kirkwood–Buff integrals preferential solvation of minoxidil by water is observed in water-rich and ethanol-rich mixtures.     

Vapor–liquid equilibria of 2-butanol + aromatic hydrocarbons at 308.15 k

Vapor–liquid equilibria (VLE) data of 2-butanol?+?benzene or toluene or o- or m- or p-xylene measured by static method at 308.15?±?0.01?K over the entire composition range are reported. The excess molar Gibbs free energies of mixing (G ^E) for these binary systems have been calculated from total vapor pressure data using Barker's method. The G ^E for these binary systems are also analyzed in terms of the Mecke–Kempter type of association model with a Flory contribution term using two interaction parameters and it has been found that this model describes well the G ^E values of binary systems benzene or toluene.     

Volumetric Properties of 1,3-Dioxolane + Toluene + o- or p-Xylene Ternary Mixtures at 25.00 °C and Atmospheric Pressure

Excess molar volumes, $ V_{123}^{\text{E}} $ V 123 E , of 1, 3-dioxolane (1) + toluene (2) + o- or p-xylene (3) ternary mixtures have been determined dilatometrically over the entire composition range at 298.15 K. For thermodynamic consistency the experimental values were fitted to Redlich–Kister Equation. The $ V_{123}^{\text{E}} $ V 123 E values of 1, 3-dioxolane (1) + toluene (2) + o- or p-xylene (3) ternary mixtures have been found to be negative over the whole composition range. It has been observed that $ V_{123}^{\text{E}} $ V 123 E values calculated by graph theory are of the same sign and magnitude with respect to their experimental values.     

Solution thermodynamics of nimodipine in some PEG 400 + ethanol mixtures

The solubility of nimodipine (NMD) in several PEG 400 + ethanol mixtures was determined at five temperatures from 293.15 to 313.15 K. The thermodynamic functions of Gibbs energy, enthalpy and entropy of solution and of mixing were obtained by using the van't Hoff and Gibbs equations from these solubility data and drug properties of fusion. The highest solubility value was obtained in PEG 400 and the lowest in ethanol at all temperatures. A non-linear enthalpy–entropy relationship was observed from a plotof enthalpy vs. Gibbs energy of solution. Accordingly, the driving mechanism for NMD solubility in ethanol-rich mixtures is the enthalpy, whereas in PEG 400-rich mixtures thedriving mechanism is the entropy, although the molecular events involved are unclear.     

Phase Equilibrium Modeling of Clathrate Hydrates of Carbon Dioxide + 1,4-Dioxine Using Intelligent Approaches

In this work, an adaptive neuro-fuzzy inference system (ANFIS) and a couple of fuzzy logic approach and genetic algorithms are utilized to serve robust inverse-based approaches for determination/prediction of the clathrate hydrate formation pressure of carbon dioxide in the presence of 1,4-dioxine, which is a most-widely implemented water “soluble” organic promoter. The gained outcomes prove the reliability and accuracy of the suggested ANFIS approach with the mean square error of 0.0034 and squared correlation coefficients of 0.9969. Thanks to the results generated by the aforementioned intelligent approaches, the models proposed in the current research contribute to high accuracy for the estimations of the phase equilibria clathrate hydrates of carbon dioxide +1,4-dioxane.      

Influence of Plasma Treatments on the Hemocompatibility of PET and PET + TiO2 Films

A dielectric barrier discharge (DBD) in helium was used to ameliorate the interface between the blood and the surface of polymeric implants: polyethylene terephthalate (PET) and PET with titanium oxide (PET + TiO₂). A higher crystallinity degree was found for the DBD treated samples. The wettability of polymers was improved after the treatment. The chemical composition, analyzed by infrared spectroscopy was preserved during the DBD treatment. The surface modifications have been correlated with polymers hemocompatibility. Concerning the polymer surface–blood interaction, the treatment induced a decrease of the interfacial tension between the blood components and the treated surfaces. The in vitro tests of hemocompatibility showed no perturbation in the blood composition when the polymer samples are present in the blood volume. An interesting result is related to the whole blood clotting time that shows a dramatic increase on the treated surfaces. Moreover, the coagulation kinetics on the treated surfaces is modified.     

Liquid–Liquid Equilibria of the Methanol + Ethylbenzene + Methylcyclohexane Ternary System at 278.15, 283.15, and 293.15 K

Liquid–liquid equilibria of the methanol + ethylbenzene + methylcyclohexane ternary system are reported at 278.15, 283.15, and 293.15 K. The effect of the temperature on the liquid–liquid equilibrium is discussed. All chemical concentrations were quantified by gas chromatography using a thermal conductivity detector. Experimental data for the ternary system are compared with values calculated by the NRTL and UNIQUAC equations. It was found that both equations gave comparable quality representations of the experimental data for this ternary system. Distribution curves were also analyzed. Data for the ternary system is available from the literature at 303.15 K.     

Solutions of cellulose in DMAc + LiCl: migration of the solute in an electrical field

For solutions of cellulose (Solucell, M_w=230 kg mol^–1) in the mixed solvent DMAc (N,N-dimethylacetamide) + LiCl, it is demonstrated by means of an electrolysis cell, subdivided into six compartments, that cellulose migrates to the anode. This observation is interpreted in terms of a field-induced opening of associations between the [DMAc]_xLi⁺ complex and the [cellulose]Cl^– complex. This understanding is corroborated by the observed changes in the positions of the menisci in the electrode compartments of the electrolysis cell. Contrary to expectations, the rate of cellulose transport does not depend on its molar mass, at least under the present conditions.     

Densities and Refractive Indices of Binary Mixtures of Olive Oil + Alkanols at 298.15 K

Densities and refractive indices of mixing of olive oil with the alkanols: methanol, ethanol, 1-propanol, 2-propanol and 1-butanol, have been measured as a function of the composition at T = 298.15 K. Excess molar volumes, $ V_{\text{m}}^{\text{E}} $ , and deviation in refractive index, Δn _D, were calculated and correlated by a Redlich–Kister type function, to derive the coefficients and estimate the standard error. For mixtures of olive oil with alkanols, $ V_{\text{m}}^{\text{E}} $ is positive, except with ethanol and methanol where a sigmoidal variation is observed. Δn _D is positive over the entire range of mole fraction. The effect of chain length of the alkanols on the excess molar volumes and deviation in refractive index of the mixtures with olive oil are discussed.     

Double [3 + 2] cycloaddition of nitrile oxides with allenoates: Synthesis of spirobidihydroisoxazoles

The double [3+2] cycloaddition of allenoates with nitrile oxides was presented. The reaction worked well under mild reaction conditions to give the spirobidihydroisoxazole in moderate to excellent yields with excellent diastereoselectivities.     

Solubility of Genistin in Ethanol/Acetone + Water and Daidzein in Ethanol + Water Co-solvent Mixtures Revisited: IBKI Preferential Solvation Method

The preferential solvation parameters (δx_1,3) of genistin in ethanol/acetone (1) + water (2) and daidzein in ethanol (1) + water (2) co-solvent mixtures at elevated temperatures were derived from available solubility data using the inverse Kirkwood–Buff integral method. The values of δx_1,3 varied non-linearly with the co-solvent (1) proportion in all the aqueous mixtures. For the three co-solvent mixtures, the values of δx_1,3 were negative in water-rich mixtures, which indicated that daidzein or genistin was preferentially solvated by water and can act as Lewis bases to establish hydrogen bonds with the proton-donor functional groups of water (1). The same behavior was also observed for daidzein in ethanol (1) + water (2) and acetone (1) + water (2) mixtures with co-solvent-rich composition. For daidzein in ethanol (1) + water (2) mixtures with composition 0.24 < x₁ < 1, and genistin in ethanol (1) + water (2) and acetone (1) + water (2) mixtures with intermediate compositions, the local mole fractions of ethanol or acetone were higher than those of the mixtures and therefore the δx_1,3 values were positive, which indicated that genistin and daidzein were preferentially solvated by the co-solvent. In these regions, daidzein and genistin were acting as a Lewis acid with ethanol or acetone molecules.