Predicted Mutual Solubilities in Water + C5-C12 Hydrocarbon Systems. Results at 298 K

Mutual solubilities of water with n-alkanes, cycloalkanes, iso-alkanes (branched alkanes), alkenes, alkynes, alkadienes, and alkylbenzenes were calculated at 298 K for 153 systems not yet measured. Recommended data for 64 systems reported in the literature were compared with the predicted values. The solubility of the hydrocarbons in water was calculated with a thermodynamically based equation, which depends on specific properties of the hydrocarbon. The concentration in the second coexisting liquid phase (water in hydrocarbon) was calculated using liquid-liquid equilibrium with an equation of state, which takes into account the self-association of water and co-association of water with π-bonds of the hydrocarbons.

Особенности влияния исходного состава органических расслаивающихся смесей в микроразмерных порах на взаимную растворимость компонентов

The influence of pore size and initial compositions of stratifying organic mixtures in microsized pores on the composition and stability of coexisting phases in a heterogeneous state has been demonstrated by means of equilibrium chemical thermodynamics. Using the example of several binary organic systems, it has been shown that, unlike macrosized phases, mutual solubilities of components in microsized pores substantially depend on the size of a pore and initial composition of a mixture, and even characters of solubility dependences on pore size are different for mixtures of different compositions. A thermodynamic interpretation of the obtained results has also been suggested based on several different mechanisms of lowering the free energy of the system.

Расслаивающиеся полимерные растворы в микроразмерных порах: фазовые переходы, индуцированные деформацией пористого материала

The influence of pore morphology on phase equilibria in stratifying polymer solutions within porous matrices has been simulated by means of equilibrium chemical thermodynamics. Using the example of liquid stratifying polybutadiene-polystyrene oligomer mixtures, we have shown that deformation of a matrix which influences on pore shapes, determines mutual solubilities of components within a pore, equilibrium volume ratios of co-existing phases and their thermodynamic stability. The change in the geometric characteristics of a pore is simulated in general by introducing a parameter corresponding to the degree of deviation of the shape of the pore walls from the spherical one. The dependences of mutual solubilities of components on pore volume within pores of different shapes are different which has been explained by the existence of several mechanisms of lowering the free energy of the system. Severe deformations of a matrix lead to suppressing the stratification in microsized pores while every composition up to the equimolar one becomes thermodynamically stable.

Correlation of water-chlorohydrocarbon mutual solubilities using a modified non-quadratic mixing rule and the Cubic-Two-State equation of state

The Cubic Two-State equation of state was employed to correlate the measured mutual solubilities of water and 23 chlorinated hydrocarbons (CHCs). Following the scheme framework laid out by Medeiros and Brindis-Flores, a nonquadratic Kabadi-Danner type mixing rule is used, where the water-water dispersive parameter is corrected due to the presence of a hydrophobic solute. The model’s three parameters were adjusted to correlate experimental binary liquid-liquid equilibrium data to relatively high accuracy. The observed minimum in CHC solubility in water near ambient conditions is reproduced reliably. Overall deviations from experimental data were 7.8% for CHC solubility in the aqueous phase and 13% for water solubility in the organic phase.

Фононная теплопроводность и фазовые равновесия в наночастицах системы Bi-Sb фрактальной формы

The thermal conductivity component associated with lattice vibrations is one of the quantities determining the thermoelectric activity of a material. We have simulated the dependences of phase composition and the phonon component of the thermal conductivity associated with it on the shape of nanoparticles of a Bi–Sb alloy with an equiatomic composition and with core–shell configuration. The shape of a particle is simulated by a coefficient corresponding to the extent of deviation of the particle shape from spherical or by its fractal dimension. It is shown that mutual solubilities of components depend on the nanoparticle shape and on the mutual arrangement of coexisting phases, and the thermodynamic equilibrium position for particles with complex morphology corresponds to the homogeneous state. Homogenization of a nanoparticle reduces the phonon component of its thermal conductivity by 70–80%.

Особенности фазовых превращений растворов полимеров в деформируемых пористых матрицах

The influence of geometric characteristics (size and shape) of a pore on phase equilibria in stratifying polymer solutions within porous matrices have been simulated by means of equilibrium chemical thermodynamics. Using the example of liquid stratifying polybutadiene-polystyrene mixtures, we have shown that a strain of a matrix which influences on pore shapes, determines mutual solubilities of components within a pore, equilibrium volume ratios of co-existing phases and their thermodynamic stability. High strains of a matrix lead to suppressing the stratification while every composition up to the equimolar one becomes thermodynamically stable.