Anjing Lou

Phase behavior studies of quaternary systems containing N-lauroyl-N-methylglucamide/alcohol/alkane/water

The three-phase behavior of quaternary systems comprising N-lauroyl-N-methylglucamide (MEGA-12)/alcohol/alkane/water has been studied using epsilon-beta fishlike phase diagrams. From the epsilon-beta fishlike phase diagrams a series of phase inversions Winsor I (2) --> III (3) --> II (2) were observed, and the hydrophilic-lipophilic balanced (HLB) plane equation for the quaternary system was deduced. Some physicochemical parameters, such as the mass fraction of alcohol in the HLB interfacial layer, A S, the coordinates of the start (beta B, epsilon B) and end points (beta E, epsilon E) of the middle-phase microemulsion, the mass fractions of MEGA-12 and alcohol in the total system (C S and C A), and the solubilities of MEGA-12 and alcohol in oil phase (S O and A O), were calculated. The effects of different alcohols, alkanes, and NaCl concentrations in the aqueous phase on the phase behavior and solubilization capacity were investigated, which indicates that alcohol with longer and alkane with shorter hydrocarbon chains have a larger solubilization capacity. NaCl concentration has little influence on the phase behavior.

A functional theoretical approach to the electrical double layer of a spherical colloid particle

Abstract By employing the iterative method in functional analysis, the governing Poisson–Boltzmann equation of a spherical colloid particle that is based on the so-called Gouy–Chapman–Stern model has been solved under general potential condition. The solution of the potential in the second iteration is a function of the distance from the center of the particle with the concentration of ions, the temperature of system and the particle charge as parameters. From this solution the radius and the surface potential of a particle have been defined and the corresponding values have been estimated with the help of the Newtons iterative method. Based on the equivalent condenser model with the same center of the particle, the correlation among the electric double layer thickness, the radius and the surface potential has been established. The analysis of the quartic equation of the thickness shows that it has a sole positive real root which is much more reasonable than the Debye reciprocal length from the Debye–Huchel approximation to represent the thickness. The calculation of the thickness can be much simplified in case of a higher concentration of ions or a higher particle charge.

Surface and colloidal properties of cyclic amides. 5. N-cyclohexyl-2-pyrrolidone -water mixtures aggregation in solution and adsorption at the air-solution interface

The aggregation of N-cyclohexyl-2-pyrrolidone (CHP) in aqueous solution and its adsorption at the air–solution interface were investigated using surface tension, pyrene solubilization, fluorescence, viscosity, freezing point, light scattering and calorimetry. It is found that CHP forms small micelles in water at a relatively high critical micelle concentration (cmc) (0.45 M). The aggregation number increases with temperature. The interior of the micelle is more polar than that of the common long-chain surfactants such as SDS. This compares with the butyl and hexyl pyrrolidone micelles reported earlier. At high CHP/H2O ratios the large exothermic heats of mixing suggest hydrate formation. The partial molar heats of dilution in the micellar range indicate that the micellar structure changes significantly with concentration. The two-dimensional (2-D) second virial coefficients of the adsorbed monolayer of CHP at the air–water interface become more negative with increase of temperature and the standard heat of adsorption is endothermic. The adsorption of CHP at the air–solution interface near the cmc corresponds to an area of 54 2A 2 per molecule.

An Analytical Solution to the Electrical Double Layer Potential for Spherical Particles: A Functional Theoretical Approach

Based on the Gouy-Chapman electrical double layer model, an analytical solution to the Poisson-Boltzmann equation describing the distribution of the electrical potential around spherical particles has been obtained. The advantage of this method is that it is not restricted to the Debye-Hückel approximation condition, where ze ψ ≪ kT. The present results compare favorably to results obtained under the ze ψ ≪ kT condition for spherical particles and to results obtained for the general solution for flat plate geometry. This approach provides an effective method for the iterative calculation of the electrical double layer potential for spherical particles.

Quantitative Structure‐Property Relationship on Prediction of the Interaction Parameters δ2 t of Organic Compounds

To predict the interaction parameters δ2 t of surfactants or organic substances in aqueous solution, a quantitative structure‐property relationship (QSPR) has been found for 30 compounds that belong to six series by using MNDO‐MOPAC7.0 software. The regressed model of δ2 t first included 7 descriptors (R 2=0.925) selected from more than 30. They are the total molecular energy E t , the total electronic energy E e , the energies of the lowest unoccupied molecular orbit and the highest occupied molecular orbit E LUMO and E HOMO, the heat of formation of molecule ΔH f , the relative number of oxygen and nitrogen atoms of the hydrophilic segment (RNNO), and the Kier and Hall index of zero order of the hydrophobic fragment of compound KH0. This correlation has been improved (R 2=0.995) when the square roots of RNNO and KH0 are considered as descriptors.

Surface and colloid properties of cyclic amides III. Surface activity and micellization of N-butyl-2-pyrrolidone in water

The aggregation and surface activity ofN-butyl-2-pyrrolidone (BP) in water is investigated using surface tension, solubilization, fluorescence and NMR methods. The micelle point is high (-1.0 M) as expected for the butyl chain length, and the aggregation number is approximately 5, with pre-association below the c.m.c. Despite the low aggregation number, the fluorescence data indicate that the interior of the aggregate is similar to pure liquid BP. The adsorption ofBP at the solution/air interface goes to a maxmum near the c.m.c., corresponding to an area of 4S ~ 1 N/molecule.

Surface and colloid properties of cyclic amides II. phase separation, surface activity and micellization in mixtures of N-hexyl-2-pyrrolidone and water

N-hexyl-2-pyrrolidone (HP) and water are partially miscible above a lower consolute temperature (LCT) of 19.1°C. The interfacial tension of the two phase system was measured as a function of temperature. HP is surface active at the air/solution interface and forms micelles in solution at all temperatures from the freezing point up to the LCT and up to 25°C in the water-rich phase above the LCT. At low water contents, water is positively adsorbed at the air/solution interface.