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Mihalj Posa - One of the best experts on this subject based on the ideXlab platform.
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effects of additives methanol and nacl from aqueous surfactant solutions on the micellisation of sodium deoxycholate and sodium cholate binary mixture in the temperature interval t 278 15 318 15 k the molar Excess Gibbs Energy and the molar Gibbs ene
The Journal of Chemical Thermodynamics, 2020Co-Authors: Mihalj Posa, Ana PilipovicAbstract:Abstract Micellisation of a binary mixture of sodium deoxycholate (SD) and sodium cholate (SC) is examined for the aqueous solution without additives (referent system for self- association process) and for the aqueous solution containing methanol, NaCl and methanol + NaCl in the temperature range T = (278.15–318.15) K. Critical micelle concentrations of mono-component surfactants and binary mixtures of surfactants at different molar ratios of mixing were determined experimentally. These values were used to calculate the mole fractions of building units in the binary mixed micelle, the interaction parameter, the molar Excess Gibbs Energy and the molar Gibbs Energy of micellisation. Effects of additives in aqueous surfactants solution on the micellisation of the binary mixture can be observed in two ways, by considering the Excess molar Gibbs Energy ( g ij e ) or by analyzing the molar Gibbs Energy of micellisation ( Δ g mM 0 ). The impact of methanol in aqueous solution is expressed differently over g ij e and Δ g mM 0 , while the effect of Na+ ion is similar for both thermodynamic functions: g ij e and Δ g mM 0 . In this paper is performed a detailed analysis of the molar Gibbs energies of micellisation: Δ g mM 0 ( 1 ) = R T x i ln c m c i + x j ln c m c j + x i ln x i + x j ln x j + β x i - x i 2 and Δ g mM 0 ( 2 ) = R T ln c m c ij and their different loading with absolute errors.
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Excess Gibbs Energy of the binary mixed micelle formation between ionic and non ionic surfactants in the set of sodium cholate sodium deoxycholate brij s10 and brij 58 at t 283 15 323 15 k
The Journal of Chemical Thermodynamics, 2020Co-Authors: Mihalj Posa, Zita Farkas Agatic, Dusan Skoric, Kosta Popovic, Janos CsanadiAbstract:Abstract Molar Excess Gibbs Energy of mixed micelle formation (ge) between ionic and non-ionic surfactants in the set of the following surfactants: sodium-cholate (SC), sodium-deoxycholate (SDC), Brij S10 (BS) and Brij 58 (B58) can be described by first order Margules function. The Regular Solution Theory (RST) hypothesis of zero Excess entropy cannot be accepted with these systems of investigated surfactants. Molar Excess entropy is probably the result of conformational entropy, while the configurational entropy is zero, and these two facts are the bases for the description of ge by first order Margules function. The interaction coefficient between the different building units of the investigated binary surfactant systems has greater value than 0, which means that there are antagonistic interactions between the surfactant molecules in the mixed micelles. According to the 1H-1H ROESY 2D spectra there are interactions between the hydrogens from the angular methyl groups of the SC (SDC) steroid skeleton and the hydrogen from the middle and terminal part of the B58 (BS10) hydrocarbon chain in the mixed micelles. The intensities of the cross-peaks and the interaction coefficients decrease with temperature, which suggests that with temperature increase the mixed micelle becomes more diffuse, i.e. less compact. There are cross-peaks in the ROESY 2D spectra between the building units of the mixed micelles, which mean that mixed micelles are formed, but the peaks don't give information about the synergistic or antagonistic effects between the surfactants.
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influence of cations of the first group of the periodic table of elements on the thermodynamic stabilization of cholic and deoxycholic acid anion micelles
Journal of Molecular Liquids, 2019Co-Authors: Mihalj Posa, Kosta Popovic, Zita Farkas AgaticAbstract:Abstract From the dependence of the specific conductivity on the total concentration of surfactants approximation can be made that micelles of cholic acid (SC) anions and deoxycholic acid (SDC) anions in the vicinity of the critical micelle concentration (cmc) do not bind counterions (β = 0). Thermodynamic stabilization of SC and SDC micelles is greatest if the aqueous solution contains CsCl, although Cs+ has the smallest surface charge density. This indicates that the mechanism that exerts the effect of the cations of the first group of the Periodic Table of Elements (PTE) on the micellization of SC and SDC depends on the ionic radii of cations, i.e. the mechanism is different for cations with a large ionic radius and for cations with a small ionic radius. If the micelles do not bind counter ions, then the cations exhibit their activity on water molecules located in the hydrophobic shell above the hydrophobic surface of the monomer. From β = 0 it follows that the Excess Gibbs Energy of micellization in the presence of cations of the first group of the PTE in the aqueous solution does not contain Debye-Huckel's Gibbs Excess Energy. Equation analogous to the Der's equation can be obtained for the critical micellar concentration ratio ln ( c m c / c m c ′ ) . The paper demonstrated that Der's equation applied to the micelles of bile salts describes the Excess Gibbs Energy of micellization.
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micellisation of the binary mixture of surfactants triton x100 and brij s10 in a water solution at t 278 15 318 15 k the Excess Gibbs Energy of the binary mixed micelles formation and its interpretation by the first order and the second order margules function
The Journal of Chemical Thermodynamics, 2019Co-Authors: Mihalj Posa, Ana PilipovicAbstract:Abstract Micellisation of the binary mixture of non-ionic surfactants Triton X100 and Brij S10 is examined. Both surfactants have polyoxyethylene chains of the same lenght, and differ in the conformational flexibility of the hydrocarbon segment. Triton X100 is the common surfactant in the biochemical laboratories, especially suitable for biological systems since it does not induce protein denaturation, while Brij surfactants show positive effects on the bioavailability of some drugs. According to the regular solution theory (RST), formed binary mixed micelles in each mole fraction of the binary mixture of Brij S10 – Triton X100 are richer in a hydrophobic component (Brij S10), while if the content of the binary mixed micelle is determined using the Rodenas function (the model independent method), then mixed micelles exist that are rich in Brij S10 and mixed micelles rich in Triton X100. According to the experimental values, RST hypothese that the Excess entropy is zero cannot be accepted. Also, the dependence of the molar Excess Gibbs Energy is not a symmetric function. The RST interaction parameter as well as the model independent Gibbs Energy show synergistic interactions between Brij S10 and Triton X100. In the infinitely diluted micellar pseudo-phases at T = (283.15-308.15) K the thermodynamic stabilization of Brij S10 and Triton X100 has the entropic origin.
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micellisation of binary mixtures of surfactants na deoxycholate na decyl sulfate and na hyodeoxycholate na decyl sulfate in water solutions rational development of the thermodynamic model for the Excess Gibbs Energy ge
Journal of Chemical & Engineering Data, 2018Co-Authors: Mihalj Posa, Ana Pilipovic, Vesna Tepavcevic, Stoja ObradovicAbstract:Micellisation of two binary mixtures, sodium decyl sulfate (NaDS)–sodium deoxycholate (NaDC) and sodium decyl sulfate (NaDS)–sodium hyodeoxychlolate (NaHDC), is examined, in consideration with the different molar fractions of the monomers (x = 0.1–0.9). In bile acids, the OH groups attached to steroid skeletons are spatially ecraned, while the sulfate group of NaDS is not ecraned. Thus, NaDC and NaHDC in relation to NaDS have different coordination numbers in the micelle pseudophase. On the basis of stereochemical analysis, rational design shows that the Excess Gibbs Energy (GE) of formation of the binary mixed micelle throughout the whole composition range can be described with a two-parameter Margules function, while the GE function from the regular solution theories is applicable only in the narrow interval of the bile salts molar fractions (x = 0.5– 0.8). Coefficient of activity (hypothetical) of the infinitely diluted mixed micelle of NaDS in the presence of NaDC shows significant thermodynamic stabi...
Ana Pilipovic - One of the best experts on this subject based on the ideXlab platform.
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effects of additives methanol and nacl from aqueous surfactant solutions on the micellisation of sodium deoxycholate and sodium cholate binary mixture in the temperature interval t 278 15 318 15 k the molar Excess Gibbs Energy and the molar Gibbs ene
The Journal of Chemical Thermodynamics, 2020Co-Authors: Mihalj Posa, Ana PilipovicAbstract:Abstract Micellisation of a binary mixture of sodium deoxycholate (SD) and sodium cholate (SC) is examined for the aqueous solution without additives (referent system for self- association process) and for the aqueous solution containing methanol, NaCl and methanol + NaCl in the temperature range T = (278.15–318.15) K. Critical micelle concentrations of mono-component surfactants and binary mixtures of surfactants at different molar ratios of mixing were determined experimentally. These values were used to calculate the mole fractions of building units in the binary mixed micelle, the interaction parameter, the molar Excess Gibbs Energy and the molar Gibbs Energy of micellisation. Effects of additives in aqueous surfactants solution on the micellisation of the binary mixture can be observed in two ways, by considering the Excess molar Gibbs Energy ( g ij e ) or by analyzing the molar Gibbs Energy of micellisation ( Δ g mM 0 ). The impact of methanol in aqueous solution is expressed differently over g ij e and Δ g mM 0 , while the effect of Na+ ion is similar for both thermodynamic functions: g ij e and Δ g mM 0 . In this paper is performed a detailed analysis of the molar Gibbs energies of micellisation: Δ g mM 0 ( 1 ) = R T x i ln c m c i + x j ln c m c j + x i ln x i + x j ln x j + β x i - x i 2 and Δ g mM 0 ( 2 ) = R T ln c m c ij and their different loading with absolute errors.
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micellisation of the binary mixture of surfactants triton x100 and brij s10 in a water solution at t 278 15 318 15 k the Excess Gibbs Energy of the binary mixed micelles formation and its interpretation by the first order and the second order margules function
The Journal of Chemical Thermodynamics, 2019Co-Authors: Mihalj Posa, Ana PilipovicAbstract:Abstract Micellisation of the binary mixture of non-ionic surfactants Triton X100 and Brij S10 is examined. Both surfactants have polyoxyethylene chains of the same lenght, and differ in the conformational flexibility of the hydrocarbon segment. Triton X100 is the common surfactant in the biochemical laboratories, especially suitable for biological systems since it does not induce protein denaturation, while Brij surfactants show positive effects on the bioavailability of some drugs. According to the regular solution theory (RST), formed binary mixed micelles in each mole fraction of the binary mixture of Brij S10 – Triton X100 are richer in a hydrophobic component (Brij S10), while if the content of the binary mixed micelle is determined using the Rodenas function (the model independent method), then mixed micelles exist that are rich in Brij S10 and mixed micelles rich in Triton X100. According to the experimental values, RST hypothese that the Excess entropy is zero cannot be accepted. Also, the dependence of the molar Excess Gibbs Energy is not a symmetric function. The RST interaction parameter as well as the model independent Gibbs Energy show synergistic interactions between Brij S10 and Triton X100. In the infinitely diluted micellar pseudo-phases at T = (283.15-308.15) K the thermodynamic stabilization of Brij S10 and Triton X100 has the entropic origin.
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micellisation of binary mixtures of surfactants na deoxycholate na decyl sulfate and na hyodeoxycholate na decyl sulfate in water solutions rational development of the thermodynamic model for the Excess Gibbs Energy ge
Journal of Chemical & Engineering Data, 2018Co-Authors: Mihalj Posa, Ana Pilipovic, Vesna Tepavcevic, Stoja ObradovicAbstract:Micellisation of two binary mixtures, sodium decyl sulfate (NaDS)–sodium deoxycholate (NaDC) and sodium decyl sulfate (NaDS)–sodium hyodeoxychlolate (NaHDC), is examined, in consideration with the different molar fractions of the monomers (x = 0.1–0.9). In bile acids, the OH groups attached to steroid skeletons are spatially ecraned, while the sulfate group of NaDS is not ecraned. Thus, NaDC and NaHDC in relation to NaDS have different coordination numbers in the micelle pseudophase. On the basis of stereochemical analysis, rational design shows that the Excess Gibbs Energy (GE) of formation of the binary mixed micelle throughout the whole composition range can be described with a two-parameter Margules function, while the GE function from the regular solution theories is applicable only in the narrow interval of the bile salts molar fractions (x = 0.5– 0.8). Coefficient of activity (hypothetical) of the infinitely diluted mixed micelle of NaDS in the presence of NaDC shows significant thermodynamic stabi...
Stoja Obradovic - One of the best experts on this subject based on the ideXlab platform.
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micellisation of binary mixtures of surfactants na deoxycholate na decyl sulfate and na hyodeoxycholate na decyl sulfate in water solutions rational development of the thermodynamic model for the Excess Gibbs Energy ge
Journal of Chemical & Engineering Data, 2018Co-Authors: Mihalj Posa, Ana Pilipovic, Vesna Tepavcevic, Stoja ObradovicAbstract:Micellisation of two binary mixtures, sodium decyl sulfate (NaDS)–sodium deoxycholate (NaDC) and sodium decyl sulfate (NaDS)–sodium hyodeoxychlolate (NaHDC), is examined, in consideration with the different molar fractions of the monomers (x = 0.1–0.9). In bile acids, the OH groups attached to steroid skeletons are spatially ecraned, while the sulfate group of NaDS is not ecraned. Thus, NaDC and NaHDC in relation to NaDS have different coordination numbers in the micelle pseudophase. On the basis of stereochemical analysis, rational design shows that the Excess Gibbs Energy (GE) of formation of the binary mixed micelle throughout the whole composition range can be described with a two-parameter Margules function, while the GE function from the regular solution theories is applicable only in the narrow interval of the bile salts molar fractions (x = 0.5– 0.8). Coefficient of activity (hypothetical) of the infinitely diluted mixed micelle of NaDS in the presence of NaDC shows significant thermodynamic stabi...
R.d. Young - One of the best experts on this subject based on the ideXlab platform.
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modeling phase equilibria and speciation in mixed solvent electrolyte systems ii liquid liquid equilibria and properties of associating electrolyte solutions
Journal of Molecular Liquids, 2006Co-Authors: Peiming Wang, Andrzej Anderko, Ronald D Springer, R.d. YoungAbstract:Abstract A comprehensive mixed-solvent electrolyte model has been extended to calculate liquid–liquid equilibria in water–organic salt systems. Also, it has been applied to calculate phase equilibria and speciation in strongly associating systems such as sulfuric acid/oleum (H2SO4+SO3+H2O) in the entire concentration range. The model combines an Excess Gibbs Energy model with detailed speciation calculations. The Excess Gibbs Energy model consists of a long-range interaction contribution represented by the Pitzer–Debye–Huckel expression, a short-range term expressed by the UNIQUAC model and a middle-range term of a second-virial-coefficient type for specific ionic interactions. The model accurately represents the thermodynamic behavior of systems ranging from infinite dilution in water to pure acids and beyond, e.g. in mixtures of H2SO4 and SO3. In particular, the model has been shown to predict speciation that is consistent with spectroscopic measurements for the H2SO4+H2O system. In addition, vapor–liquid and liquid–liquid equilibria can be accurately reproduced in mixtures that show complex phase behavior.
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a speciation based model for mixed solvent electrolyte systems
Fluid Phase Equilibria, 2002Co-Authors: Peiming Wang, Andrzej Anderko, R.d. YoungAbstract:A comprehensive model has been developed for the calculation of speciation, phase equilibria, enthalpies, heat capacities and densities in mixed-solvent electrolyte systems. The model incorporates chemical equilibria to account for chemical speciation in multiphase, multicomponent systems. For this purpose, the model combines standard-state thermochemical properties of solution species with an expression for the Excess Gibbs Energy. The Excess Gibbs Energy model incorporates a long-range electrostatic interaction term expressed by a Pitzer–Debye–Huckel equation, a short-range interaction term expressed by the UNIQUAC model and a middle-range, second virial coefficient-type term for the remaining ionic interactions. The standard-state properties are calculated by using the Helgeson– Kirkham–Flowers equation of state for species at infinite dilution in water and by constraining the model to reproduce the Gibbs Energy of transfer between various solvents. The model is capable of accurately reproducing various types of experimental data for systems including aqueous electrolyte solutions ranging from infinite dilution to fused salts, electrolytes in organic or mixed, water + organic, solvents up to the solubility limit and acid–water mixtures in the full concentration range. © 2002 Elsevier Science B.V. All rights reserved.
Dana Dragoescu - One of the best experts on this subject based on the ideXlab platform.
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isothermal vapour liquid equilibria for nitromethane or nitroethane 1 4 dichlorobutane binary systems at temperatures between 343 15 and 363 15 k
The Journal of Chemical Thermodynamics, 2013Co-Authors: Mariana Teodorescu, Dana Dragoescu, Daniela GheorgheAbstract:Isothermal vapor–liquid equilibrium (VLE) data are reported at three temperatures, (343.15, 353.15, and 363.15) K, for the binary mixtures containing nitromethane or nitroethane with 1,3-dichloropropane. For the measurements an all-glass ebulliometer was used, which allows sampling from both phases in equilibrium. The experimental data were correlated using the nonrandom two-liquid (NRTL) and universal quasichemical activity coefficient (UNIQUAC) Excess Gibbs Energy models by means of maximum likelihood method, taking into account the vapor phase imperfection in terms of the second virial coefficients. Both systems are azeotropic and show positive deviations from ideal behavior. The experimental VLE data are analyzed in terms of the modified UNIFAC (Do) model.
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isothermal vapour liquid equilibria for 1 2 dichloroethane nitromethane and nitroethane binary systems at temperatures between 333 15 and 353 15k
Fluid Phase Equilibria, 2010Co-Authors: Mariana Teodorescu, Alexandru Barhala, Dana DragoescuAbstract:Abstract Isothermal vapour–liquid equilibrium (VLE) data are reported at three temperatures, 333.15, 343.15 and 353.15 K, for binary mixtures containing 1,2-dichloroethane with nitromethane or nitroethane. Use has been made of an ebulliometer which allows sampling from both phases in equilibrium. The experimental data were correlated using the Redlich–Kister, Wilson, NRTL and UNIQUAC Excess Gibbs Energy models by means of the maximum likelihood method, taking into account the vapour phase imperfection in terms of the second virial coefficients. Both systems are zeotropic and show positive deviations from ideal behaviour. The experimental VLE data are analysed in terms of the Modified UNIFAC (Do) model.
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vapour pressures and Excess Gibbs Energy of propane 2 one chloroalkanes binary mixtures
Fluid Phase Equilibria, 1998Co-Authors: Dana Dragoescu, Alexandru Barhala, Rodica VilcuAbstract:Total vapour pressures have been measured for binary mixtures of propane-2-one with 1-chloropentane (I), 1,3-dichloropropane (II), and 1,1,1-trichloroethane (III), at 298.15, 303.15, 308.15 and 313.15 K, by a static method. The data were reduced using Barker's method and different expressions for Excess Gibbs Energy were tested. The results evidenced positive (for (I) and (III) mixtures) and negative (for (II) mixture) deviations from ideality.
