Surface Properties Of Binary Mixtures Research Articles

Effect of temperature and composition on the surface tension and surface properties of binary mixtures containing DMSO and short chain alcohols

Surface tension of binary mixtures of methanol, ethanol and isopropanol with DMSO (dimethyl sulfoxide) was measured over the whole range of composition at atmospheric pressure of 82.5kPa within the temperatures between (298.15 and 328.15)K. The experimental measurements were used to calculate in surface tension deviations (Δσ). The sign of Δσ for all temperatures is negative (except of methanol/DMSO system) because of the factors of hydrogen bonding and dipole–dipole interactions in the DMSO-alcohol systems. Surface tension values of the binary systems were correlated with FLW, MS, RK and LWW models. The mean standard deviation obtained from the comparison of experimental and calculated surface tension values for binary systems with three models (FLW, MS and RK) at various temperatures is less than 0.83. Also, the results of the LWW model were used to account for the interaction energy between alcohols and DMSO in binary mixtures. The temperature dependence of σ (surface tension) at fixed composition of solutions was used to estimate surface enthalpy, Hs, and surface entropy, Ss. The results obtained show that the values of the thermodynamic parameters for alcohol/DMSO mixtures decrease with increasing alkyl chain length of alcohol. Finally, the results are discussed in terms of surface mole fraction and lyophobicity using the extended Langmuir (EL) isotherm.

Tuning Micelle Dimensions and Properties for Stabilizing Membrane Protein Fold and Function

One major bottleneck to the investigation of membrane proteins is the stabilization of structure and function in detergents and lipid bilayers after purification from the native membrane. Detergents are the most successful membrane mimic, thus far, for NMR and X-ray crystallography structure determination of membrane proteins. However, the current empirical screening of detergents that stabilize protein function and fold is laborious, costly, and often is not successful. To better understand the physical determinants that stabilize a protein-detergent complex, we have systematically investigated the properties of detergent micelles. Specifically, we have determined that binary detergent mixtures form ideally mixed micelles and that many physical properties are different from the pure individual micelles and vary linearly with micelle mole fraction. The predictability of the shape, size, and surface properties of binary mixtures expands the molecular toolkit for applications that utilize detergents and provide a means to systematically test the influence these properties have on membrane protein fold and function. Our progress towards correlating detergent micelle physical properties with membrane protein structure and function will be presented.

How do temperature and chemical structure affect surface properties of aqueous solutions of carboxylic acids?

• The surface properties of binary systems of aqueous–organic acid calculated. • The activity coefficients of components have been calculated by UNIFAC methods. • The interaction energy values were calculated by using LWW model. • The U 12 –U 11 value shows same behavior for studied systems with rising temperature. • The relative Gibbs adsorption increases with increasing the length of carboxylic acid chain. Surface properties of binary mixtures of organic acids (formic, acetic, propanoic and butanoic acids) with water have been calculated by surface tension data at various temperatures (293.15–323.15) K. The surface tension data over the whole mole fraction range are correlated by the Li et al. (LWW) model, then the interaction energy between organic acids and water have been calculated with the results of this model. Also, adsorption isotherms of binary aqueous solutions of organic acids are determined using Gibbs adsorption equation with experimental data found in the literature and using the UNIFAC group contribution method. The values of adsorption for mixtures of organic acids/water increases with increasing the alkyl chain length of organic acid at different temperatures. Finally, the results have been discussed in terms of surface concentration and lyophobicity using the extended Langmuir (EL) isotherm. The results provide information on the molecular interactions between unlike molecules that exist at the surface and the bulk.

Prediction of the Surface Tension, Surface Concentration and the Relative Gibbs Adsorption Isotherm of Non-ideal Binary Liquid Mixtures

Surface properties of binary mixtures of 1,2-ethanediol, 1,2-propanediol and 1,4-butanediol with acetonitrile have been measured by the surface tension method at T = 298.15 K and atmospheric pressure. The surface tension has been predicted based on the Suarez method. This method combines a model for the description of surface tension of liquid mixtures by using the UNIFAC group contribution method for calculation of activity coefficients. Also, the results have been discussed in terms of surface concentration and lyophobicity using the extended Langmuir isotherm. The results provide information on the molecular interactions between the unlike molecules that exist at the surface and the bulk phase. Finally, experimental values of the surface tension have been correlated by the Redlich–Kister and Wang–Chen polynomial equations over the whole mole fraction range.

Study of surface tension and surface properties of binary systems of DMSO with long chain alcohols at various temperatures

Surface tensions of binary mixtures of DMSO (dimethyl sulphoxide) with a series of long chain aliphatic alcohols (1-propanol, 1-butanol, and 1-hexanol) were measured as a function of composition using the ring detachment method in the temperature range between (288.15 and 328.15)K. The surface tension results are used to describe quantitatively the nature, properties, and compositions of surface layers in binary liquid mixtures. The temperature influence on the behaviour of surface tensions and surface properties of binary mixtures has often been used to obtain information about solute structural effects on DMSO. The surface tension of the above mentioned binary systems were correlated with empirical and thermodynamic based models. The average relative error obtained from the comparison of experimental and calculated surface tension values for 15 binary systems with three models is less than 1%. In addition to finding more information about the surface structure of binary mixtures, surface mole fraction was calculated using an extended Langmuir model (EL). The temperature dependence of σ at fixed composition of solutions was used to estimate surface enthalpy, Hs, and surface entropy, Ss. The results provide information on the molecular interactions between the unlike molecules that exist at the surface and the bulk.

Properties of Sodium Methyl Ester Alpha‐Sulfo Alkylate/Trimethylammonium Bromide Mixtures

AbstractThe surface properties of binary mixtures of anionic sodium methyl ester α‐sulfo alkylate (CmMES) and cationic alkyl trimethylammonium bromide (CnTAB) of different carbon chain length have been studied in the present work. The critical micelle concentration (CMC) that was obtained from the plots of surface tension (γ) versus concentration showed that mixed surfactants have CMC values that were about 10 times lower than their single components. The large negative values for both interaction parameters suggest the existence of strong synergism between the oppositely charged surfactant molecules. The effect of hydrocarbon chain length of either surfactant was also compared and results showed that the effect of cationic surfactant chain length dominated that of the anionic surfactants. It was also discovered that certain mixed surfactant combinations behave differently from the expected trend.

Synergistic interaction of Gemini surfactant pentanediyl-1,5-bis(dimethylcetylammonium bromide) with conventional (ionic and nonionic) surfactants and its impact on the solubilization

The structure of Gemini surfactants makes them potentially useful candidates in terms of their performance, particularly in mixed micelles for different surfactant applications. We have studied mixed micellization and surface properties of binary mixtures of cationic Gemini pentanediyl-1,5-bis(dimethylcetylammonium bromide) (G5, 16-5-16) with conventional cationic cetylpyridinium chloride (CPC), anionic sodium bis(2ethylhexylsulfosuccinate) (AOT), and nonionic polyoxyethylene 10 cetyl ether (Brij 56) in detail by conductometric and tensiometric methods. The interfacial and bulk behaviors were investigated using theoretical models of Clint, Rubingh, Rosen, and Maeda to explain and compare the results of binary mixtures of G5 with the conventional surfactants. The synergism was observed in all the binary systems in the micelle as well as at the interface with expansion of molecular area per molecule. Greater synergistic interaction in the micelles has been found to reduce the solubilizing capacity towards polyaromatic hydrocarbons (PAHs).

Application of the UNIFAC model for prediction of surface tension and thickness of the surface layer in the binary mixtures

Surface properties of binary mixtures of (alkanol with acetonitrile) have been measured by surface tension method at T = 298.15 K and atmospheric pressure. The UNIFAC method is used for calculation activity coefficients of surface and bulk phases. Also, the surface tension has been predicted based on the Suarez method. This method combines a model for the description of surface tension of liquid mixtures with a UNIFAC group contribution method for the calculation of activity coefficient. Two techniques for calculation of molar surface areas, based on Paquette areas and Rasmussen areas are tested. On comparing the computed values of surface tension by the present approaches with experimental data, satisfactory results have been observed. In addition, the relative Gibbs adsorption and the surface mole fraction have been evaluated using this model. It is possible to calculate the thickness of liquid–vapor interfaces starting from surface tension data. A novel procedure is developed to obtain the thickness of liquid–vapor interfaces as a function of composition in binary systems.

Interaction of a cationic gemini surfactant with conventional surfactants in the mixed micelle and monolayer formation in aqueous medium

Mixed micellization and surface properties of binary mixtures of cationic gemini surfactant butanediyl- α , ω -bis(dimethylcetylammonium bromide) (G4, 16-4-16) with conventional surfactants cetylpyridinium chloride (CPC), sodium bis(2-ethylhexyl)sulfosuccinate (AOT), and polyoxyethylene 10 cetyl ether (Brij56) have been studied using conductometric and tensiometric methods. To explain and compare the results theoretical models of Rubingh, Rosen, Clint, and Maeda have been used to obtain the interaction parameter, minimum area per molecule, surface excess, mixed micelle composition, free energies of micellization and adsorption, and activity coefficients. The activity coefficients and experimental critical micelle concentration (cmc) values are less than unity indicating synergism in micelles as well as at interface. Also, expansion of the minimum area per molecule was observed in the binary systems supported by low values of packing parameter.

Experimental and theoretical study of surface tension of binary mixtures of (n-alkyl acetates + heptane, benzene, and toluene)

Surface properties of binary mixtures of (n-alkyl acetates + heptane, benzene, and toluene) have been measured by surface tension method at T = 298.15 K and atmospheric pressure. Also, the surface tension has been predicted based on the Suarez method. This method combines a model for the description of surface tension of liquid mixtures with a group contribution method for the calculation of activity coefficient. The mean relative standard deviations obtained from the comparison of experimental (measured) and calculated surface tension values for the eight binary systems are less than 1.5%, which leads to concluding that the model shows a good accuracy in different situations in comparison with other predicted equations. In addition, the relative Gibbs adsorption and the surface mole fraction have been evaluated using this model. The surface tension deviations were calculated from experimental results and have been fitted to the Redlich–Kister type polynomial relation.

Surface Properties of Binary Mixtures of Ethylene Glycol with a Series of Aliphatic Alcohols (1-Pentanol, 1-Hexanol, and 1-Heptanol)

Surface tensions of binary mixtures of ethylene glycol and a homologous series of aliphatic alcohols (1-pentanol, 1-hexanol, and 1-heptanol) were measured as a function of composition using the ring detachment method in the temperature range between (298.15 and 318.15) K. Temperature influence on the behavior of surface tensions and surface properties of binary mixtures has often been used to obtain information about solute structural effects on ethylene glycol. Values of surface tension were correlated with temperature and mole fraction. The experimental data have been used to calculate the surface tension deviation, δσ, as a function of mole fraction, and values obtained are fitted to the Redlich−Kister polynomial equation to obtain the coefficients and the standard errors. The maximum deviation was in both cases always less than 0.5 %. The temperature dependence of σ at fixed composition of solutions was used to estimate surface enthalpy, Hs, and surface entropy, Ss.

Effect of microheterogeneity on bulk and surface properties of binary mixtures of polyoxyethene glycol monobutyl ethers with water

Solution properties of aqueous mixtures of the homologous series of polyoxyethene glycol mono-n-butyl ethers C4H9O(CH2CH2O) m H (where m=1 to 3) have been investigated using surface tension, density, viscosity and13C NMR techniques. From the experimental data, excess volume and deviation of viscosity and free energy of activation of flow were evaluated and discussed in terms of the molecular interactions between the components. Surface activity of polyoxyethene glycol mono ethers in aqueous dilute solutions was evident from surface tension measurements. Thermodynamic properties of adsorption and apparent micellization or critical aggregation concentration (CAC) in these systems were evaluated and discussed. The CAC values and the aggregation numbers obtained from13C NMR chemical shift data indicate an increase in hydrophobicity with an increase in the value of m, in the polyoxyethene glycol mono-n-butyl ethers, and also agrees with the results obtained from surface tension measurements.

Surface properties of binary mixtures of some pulmonary surfactant components.

The dynamic surface pressure-area properties of pure and binary mixed films of rac-1,2-dipalmitoyl-glycero-3-phosphocholine, 1,2-diocoyl-sn-glycero-3-phosphocholine and cholesterol were investigated at 23 degrees C and 37 degrees C. The pure films and binary mixtures of rac-1,2-dipalmitoyl-glycero-3-phosphocholine: 1,2-dioeoyl-sn-glycero-3-phosphocholine and rac-1,2-dipalmitoyl-glycero-3-phosphocholine:cholesterol were characterized both for dilute surface initial concentrations of 150 Angstrom 2/molecule and for surface excess initial values of 15-50 Angstrom 2/molecule. The results show that the addition of 1,2-dioeoyl-sn-glycero-3-phosphocholine or cholesterol in a binary film with rac-1,2 dipalmitoyl-glycero-3-phosphocholine acts to improve the surface reentry and respreading properties over those of pure rac-1,2-dipalmitoyl-glycero-3-phosphocholine films upon dynamic compression past collapse. This effect is even more pronounced at 37 degrees C than at 23 degrees C, as demonstrated by the application of a collapse plateau ratio criterion. The enhanced dynamic respreading correlates with the effect of 1,2-dioleoyl-sn-glycero-3-phosphocholine and cholesterol in decreasing the gel to liquid crystal transition temperature of rac-1,2-dipalmitoyl-glycero-3-phosphocholine water dispersons, as well as with their facilitation of post-collapse dynamic surface pressure relaxation in binary films with rac-1,2-dipalmitoyl-glycero-3-phosphocholine.