The Experts below are selected from a list of 273 Experts worldwide ranked by ideXlab platform
V. B. Fainerman - One of the best experts on this subject based on the ideXlab platform.
-
adsorption of surfactants and proteins at the interface between their aqueous solution drop and air saturated by Hexane vapour
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2017Co-Authors: V. B. Fainerman, E V Aksenenko, S V Lylyk, Yu I Tarasevich, R MillerAbstract:Abstract The adsorption of proteins (β-lactoglobulin, β-casein) and the oxyethylated non-ionic surfactants C10EO8 and C14EO8 at the aqueous solution/air interface is strongly enhanced and accelerated by the presence of Hexane vapour in the air phase caused by the co-adsorption of Hexane molecules. Due to this Hexane co-adsorption, the dependence of dilational visco-elasticity modulus on surface pressure is shifted towards larger surface pressure values. The adsorption kinetics of the studied non-ionic surfactants shows the same picture as that observed for the two proteins. In contrast, the desorption process of the Hexane molecules from a pre-adsorbed mixed adsorption layer is very slow. This decelerated desorption is explained by a rather large desorption energy required by the Hexane molecules. The experimental data are compared with several theoretical models developed earlier. The results allow estimating the activation energy for the Hexane desorption from adsorption layers of the two studied non-ionic surfactants.
-
Mixed Protein/Hexane Adsorption Layers Formed at the Surface of Protein Solution Drops Surrounded by Hexane Vapor
Advanced Materials Interfaces, 2016Co-Authors: Reinhard Miller, Eugene V. Aksenenko, Volodymyr I. Kovalchuk, D.v. Trukhin, Yuri I. Tarasevich, V. B. FainermanAbstract:The surface tension of aqueous solution drops of s-casein, s-lactoglobulin, and human serum albumin at the interface to air and Hexane saturated air are measured by drop profile analysis tensiometry. The results indicate that the dynamic and equilibrium surface tension for a Hexane vapor atmosphere are considerably lower as compared to the values at the interface with pure air. The experiments are performed with the initial adsorption of protein followed by Hexane adsorption, and with subsequent removal of Hexane from the measuring cell after equilibrium is attained. Two models are proposed, both of which assume the diffusion of protein in the solution and either diffusion-governed or barrier-governed Hexane coadsorption. The new developed theoretical equilibrium model assumes a double layer adsorption in these systems, with the first layer composed of protein mixed with Hexane and the second layer formed by Hexane molecules only. The experimental and calculated equilibrium surface tension data are in a perfect agreement. Note the model parameters are exactly the same as those found for the individual compounds.
-
Effect of partial vapor pressure on the co-adsorption of surfactants and Hexane at the water/Hexane vapor interface
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2015Co-Authors: N. Mucic, V. B. Fainerman, Aliyar Javadi, N. Moradi, Eugene V. Aksenenko, Reinhard MillerAbstract:The adsorption of surfactants from aqueous solution at the water/air interface is changed when the air phase contains Hexane vapor. This co-adsorption of surfactant and Hexane depends on the Hexane vapor pressure. A thermodynamic model developed for the adsorption of surfactant mixtures can be adapted to the present situation. The surfactants studied were SDS, C12TAB and C12DMPO, and the dependence of their adsorption characteristics on the partial Hexane vapor pressure was determined. The co-adsorption of Hexane from the vapor phase increases the surface activity of the adsorbing surfactants.
-
Effects of dodecanol on the adsorption kinetics of SDS at the water–Hexane interface
Journal of Colloid and Interface Science, 2010Co-Authors: Aliyar Javadi, Dieter Vollhardt, V. B. Fainerman, N. Mucic, Reinhard MillerAbstract:Abstract Even though sodium dodecyl sulphate (SDS) is the most frequently studied surfactant, its properties at liquid interfaces are not easily accessible. This is mainly caused by the fact that in aqueous solution SDS is subject to hydrolysis, by which the homologous dodecanol (C12OH) is formed. Due to its enormously high surface activity it competes with SDS at the interface. We demonstrate here that this “natural” impurity C12OH does not remarkably affect the adsorption dynamics of SDS at the water/Hexane interface, due to its high solubility in Hexane. Therefore, the dynamic adsorption properties can be determined independent of disturbing dodecanol effects. The surfactant adsorbs diffusion controlled and the interfacial tension isotherm at the water/Hexane interface is well described by a Frumkin model. However complementary experiments via direct admixture of dodecanol in Hexane indicate a significant decrease in interfacial tension of the water–Hexane interface at concentrations higher than 10−3 mol/l in Hexane. This condition may happen when the oil phase is distributed as small droplets in a high concentrated solution of SDS. The distribution coefficient of C12OH between water and Hexane is estimated from adsorption experiments to be Kp = co/cw = 6.7 × 103.
Peter Wasserscheid - One of the best experts on this subject based on the ideXlab platform.
-
separation of 1 hexene and n Hexane with ionic liquids
Fluid Phase Equilibria, 2006Co-Authors: Wolfgang Arlt, Peter WasserscheidAbstract:Abstract This work deals with the separation of 1-hexene and n -Hexane as the representation of olefins and paraffins with ionic liquids, as well as N -methyl-2-pyrrolidone (NMP) screened by computer-aided molecular design (CAMD). On the basis of conformation analysis of solvents and ionic liquids, the conductor-like screening model for real solvents (COSMO-RS) was used to make a priori prediction for suitable ionic liquids. It was found that the suitable ionic liquids should have small molecular volume, unbranched group and sterical shielding effect around anion charge center. Headspace-gas chromatography (HSGC) experiments were done at 313.15 and 333.15 K. It was verified that the anion with sterical shielding effect around anion charge center is favorable for increasing the selectivity, and [C 8 Chin] + [BTA] − is the best among all the ionic liquids investigated. The separation mechanism of olefins and paraffins with ionic liquids can be explained by the theory of Prausnitz and Anderson's solution thermodynamics. This work also can be extended to the separation of other hydrocarbons with ionic liquids since the separation mechanism between n -Hexane/1-hexene and other hydrocarbons is consistent.
R Miller - One of the best experts on this subject based on the ideXlab platform.
-
adsorption of surfactants and proteins at the interface between their aqueous solution drop and air saturated by Hexane vapour
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2017Co-Authors: V. B. Fainerman, E V Aksenenko, S V Lylyk, Yu I Tarasevich, R MillerAbstract:Abstract The adsorption of proteins (β-lactoglobulin, β-casein) and the oxyethylated non-ionic surfactants C10EO8 and C14EO8 at the aqueous solution/air interface is strongly enhanced and accelerated by the presence of Hexane vapour in the air phase caused by the co-adsorption of Hexane molecules. Due to this Hexane co-adsorption, the dependence of dilational visco-elasticity modulus on surface pressure is shifted towards larger surface pressure values. The adsorption kinetics of the studied non-ionic surfactants shows the same picture as that observed for the two proteins. In contrast, the desorption process of the Hexane molecules from a pre-adsorbed mixed adsorption layer is very slow. This decelerated desorption is explained by a rather large desorption energy required by the Hexane molecules. The experimental data are compared with several theoretical models developed earlier. The results allow estimating the activation energy for the Hexane desorption from adsorption layers of the two studied non-ionic surfactants.
Zongcheng Li - One of the best experts on this subject based on the ideXlab platform.
-
liquid liquid equilibria of multi component systems including n Hexane n octane benzene toluene xylene and sulfolane at 298 15 k and atmospheric pressure
Fluid Phase Equilibria, 2000Co-Authors: Jian Chen, Liping Duan, Jianguo Mi, Zongcheng LiAbstract:Abstract Liquid–liquid equilibrium (LLE) data were measured at 298.15 K and atmospheric pressure for six ternary systems: n- Hexane + benzene + sulfolane ,n- Hexane + toluene + sulfolane ,n- Hexane + xylene + sulfolane ,n- octane + benzene + sulfolane ,n- octane + toluene + sulfolane ,n- octane + xylene + sulfolane ; three quaternary systems :n- Hexane +n- octane + benzene + sulfolane ,n- Hexane + benzene + toluene + sulfolane and n- octane + toluene + xylene + sulfolane ; one quinary system :n- Hexane +n- octane + benzene + toluene + sulfolane . The equilibrium data of ternary systems were used to regress interaction parameters in non-random two-liquid (NRTL) equation. These parameters were directly used to predict equilibrium data of quaternary and quinary systems. The predicted data are in good agreement with experimental data.
Armin De Meijere - One of the best experts on this subject based on the ideXlab platform.
-
synthesis of spiro 2 2 pentanes and spiro 2 3 Hexanes employing the me3al ch2i2 reagent
European Journal of Organic Chemistry, 2017Co-Authors: Ilfir R Ramazanov, Tatyana P Zosim, Usein M. Dzhemilev, Rita N Kadikova, Armin De MeijereAbstract:Substituted alkylidenecyclopropanes reacted with 5 equivalents each of Me3Al and CH2I2 at room temperature in Hexane to give 1-mono- and 1,1-disubstituted spiro[2.2]pentanes in high yields. Surprisingly, the same reaction with substituted alkylidenecyclopropanes in CH2Cl2 afforded exclusively 1,1-disubstituted spiro[2.3]Hexanes. The transformation of 1,1-diphenylspiro[2.2]pentane into 1,1-diphenylspiro[2.3]Hexane was studied with the use of CD2I2 and a plausible mechanism was suggested. The reaction of substituted alkylidenecyclobutanes with the Me3Al/CH2I2 reagent in CH2Cl2 gave only 1,1-disubstituted spiro[2.3]Hexanes.
