Concentrated surfactant/alcohol/oil/brine systems are to be used in certain enhanced oil recovery... more Concentrated surfactant/alcohol/oil/brine systems are to be used in certain enhanced oil recovery processes. However, there have been no studies showing the influence of hydrostatic pressure up to reservoir conditions on the phase behavior of either model or candidate surfactant systems. This paper presents results observed with a model system that has several phases including liquid crystalline (anisotropic) microstructures and with a candidate system that shows surfactant phase transitions as a function of salinity. In both cases, surprisingly low pressures can have significant effects on the system. The equilibrium phase behavior changes in the first case, while both equilibrium and transient effects are seen in the latter. The potassium oleate systems were prepared from a stock 1.0 N KOH solution to which n-hexanol and oleic acid were added and shaken and then to which n-hexadecane was added. Agitation was continued until only one phase was seen at room temperature. The final co...
Scientific projects frequently involve measurements of thermophysical, thermochemical, and other ... more Scientific projects frequently involve measurements of thermophysical, thermochemical, and other related properties of chemical compounds and materials. These measured property data have significant potential value for the scientific community, but incomplete and inaccurate reporting often hampers their utilization. The present IUPAC Technical Report summarizes the needs of chemical engineers and researchers as consumers of these data and shows how publishing practices can improve information transfer. In the Report, general principles of Good Reporting Practice are developed together with examples illustrating typical cases of reporting issues. Adoption of these principles will improve the quality, reproducibility, and usefulness of experimental data, bring a better level of consistency to results, and increase the efficiency and impact of research. Closely related to Good Reporting Practice, basic elements of Good Research Practice are also introduced with a goal to reduce the num...
Fluctuation Theory develops exact relations between integrals of molecular correlation functions ... more Fluctuation Theory develops exact relations between integrals of molecular correlation functions and concentration derivatives of pressure and chemical potential. These quantities can be usefully correlated, particularly for mechanical and thermal properties of pure and mixed dense fluids and for activities of strongly nonideal liquid solutions. The expressions yield unique formulae for the desirable thermodynamic properties of activity and density. The molecular theory origins of the flucuation properties, their behavior for systems of technical interest and some of their successful correlations will be described. Suggestions for fruitful directions will be suggested.
ABSTRACT The recently proposed model [Geochim. Cosmochim. Acta 64 (2000) 495; Geochim. Cosmochim.... more ABSTRACT The recently proposed model [Geochim. Cosmochim. Acta 64 (2000) 495; Geochim. Cosmochim. Acta 64 (2000) 2779] for correlating the infinite dilution partial molar properties of aqueous nonelectrolytes is briefly outlined. The approach is fundamentally based on the A12=V20/κRT parameter, related to the infinite dilute solute–water direct correlation function integral. The A12 parameter is considered as a semiempirical function of temperature and density. At supercritical temperatures thermodynamic integrations of this function allow calculation of all thermodynamic functions of hydration (V20, ΔhG0, ΔhH0 and ΔhCp0) of a solute. An extension to subcritical conditions is done using an auxiliary ΔhCp0(T, Pr)-function, which describes the temperature course of the heat capacity of hydration of a solute at Pr=28 MPa and subcritical temperatures. The variations of the ΔhCp0(T, Pr)-function are constrained by known values of ΔhG0, ΔhH0 and ΔhCp0 at ambient and supercritical conditions. This model, which was used earlier to correlate properties of a few dissolved gases, is successfully employed here to describe V20, ΔhG0, ΔhH0 and ΔhCp0 experimental results for a number of aqueous nonelectrolytes, including ones of high polarity (alcohols, amines, acids and amides) and/or large size (hexane and benzene).
Systems with azeotropes cannot be separated by simple distillation since the vapor and liquid com... more Systems with azeotropes cannot be separated by simple distillation since the vapor and liquid compositions are the same. Variation of the applied pressure can shift the azeotropic composition out of the range of purification of a single column or may allow pressure swing operation of two columns. Because of the sensitivity of column size to accurate estimates of the relative volatility, it is important to use reliable phase equilibrium thermodynamics when exploring the possibility of varying pressure to avoid an azeotrope. Based on an analysis of the pressure sensitivity of azeotropic compositions, we show examples of the impact of different modeling strategies for binary and multicomponent mixtures.
Concentrated surfactant/alcohol/oil/brine systems are to be used in certain enhanced oil recovery... more Concentrated surfactant/alcohol/oil/brine systems are to be used in certain enhanced oil recovery processes. However, there have been no studies showing the influence of hydrostatic pressure up to reservoir conditions on the phase behavior of either model or candidate surfactant systems. This paper presents results observed with a model system that has several phases including liquid crystalline (anisotropic) microstructures and with a candidate system that shows surfactant phase transitions as a function of salinity. In both cases, surprisingly low pressures can have significant effects on the system. The equilibrium phase behavior changes in the first case, while both equilibrium and transient effects are seen in the latter. The potassium oleate systems were prepared from a stock 1.0 N KOH solution to which n-hexanol and oleic acid were added and shaken and then to which n-hexadecane was added. Agitation was continued until only one phase was seen at room temperature. The final co...
Scientific projects frequently involve measurements of thermophysical, thermochemical, and other ... more Scientific projects frequently involve measurements of thermophysical, thermochemical, and other related properties of chemical compounds and materials. These measured property data have significant potential value for the scientific community, but incomplete and inaccurate reporting often hampers their utilization. The present IUPAC Technical Report summarizes the needs of chemical engineers and researchers as consumers of these data and shows how publishing practices can improve information transfer. In the Report, general principles of Good Reporting Practice are developed together with examples illustrating typical cases of reporting issues. Adoption of these principles will improve the quality, reproducibility, and usefulness of experimental data, bring a better level of consistency to results, and increase the efficiency and impact of research. Closely related to Good Reporting Practice, basic elements of Good Research Practice are also introduced with a goal to reduce the num...
Fluctuation Theory develops exact relations between integrals of molecular correlation functions ... more Fluctuation Theory develops exact relations between integrals of molecular correlation functions and concentration derivatives of pressure and chemical potential. These quantities can be usefully correlated, particularly for mechanical and thermal properties of pure and mixed dense fluids and for activities of strongly nonideal liquid solutions. The expressions yield unique formulae for the desirable thermodynamic properties of activity and density. The molecular theory origins of the flucuation properties, their behavior for systems of technical interest and some of their successful correlations will be described. Suggestions for fruitful directions will be suggested.
ABSTRACT The recently proposed model [Geochim. Cosmochim. Acta 64 (2000) 495; Geochim. Cosmochim.... more ABSTRACT The recently proposed model [Geochim. Cosmochim. Acta 64 (2000) 495; Geochim. Cosmochim. Acta 64 (2000) 2779] for correlating the infinite dilution partial molar properties of aqueous nonelectrolytes is briefly outlined. The approach is fundamentally based on the A12=V20/κRT parameter, related to the infinite dilute solute–water direct correlation function integral. The A12 parameter is considered as a semiempirical function of temperature and density. At supercritical temperatures thermodynamic integrations of this function allow calculation of all thermodynamic functions of hydration (V20, ΔhG0, ΔhH0 and ΔhCp0) of a solute. An extension to subcritical conditions is done using an auxiliary ΔhCp0(T, Pr)-function, which describes the temperature course of the heat capacity of hydration of a solute at Pr=28 MPa and subcritical temperatures. The variations of the ΔhCp0(T, Pr)-function are constrained by known values of ΔhG0, ΔhH0 and ΔhCp0 at ambient and supercritical conditions. This model, which was used earlier to correlate properties of a few dissolved gases, is successfully employed here to describe V20, ΔhG0, ΔhH0 and ΔhCp0 experimental results for a number of aqueous nonelectrolytes, including ones of high polarity (alcohols, amines, acids and amides) and/or large size (hexane and benzene).
Systems with azeotropes cannot be separated by simple distillation since the vapor and liquid com... more Systems with azeotropes cannot be separated by simple distillation since the vapor and liquid compositions are the same. Variation of the applied pressure can shift the azeotropic composition out of the range of purification of a single column or may allow pressure swing operation of two columns. Because of the sensitivity of column size to accurate estimates of the relative volatility, it is important to use reliable phase equilibrium thermodynamics when exploring the possibility of varying pressure to avoid an azeotrope. Based on an analysis of the pressure sensitivity of azeotropic compositions, we show examples of the impact of different modeling strategies for binary and multicomponent mixtures.
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