Surfactants phase behavior

R. G. Laughlin, The Aqueous Phase Behavior of Surfactants, Academic, London, 1994. 

For nonionic amphiphiles, the effects of temperature on the phase behavior are large and the effects of inorganic electrolytes are very small. However, for ionic surfactants temperature effects are usually small, but effects of inorganic electrolytes are large. Most common electrolytes (eg, NaCl)... 

In some of these models (see Sec. Ill) the surfactants are still treated as flexible chains [24]. This allows one to study the role of the chain length and chain conformations. For example, the chain degrees of freedom are responsible for the internal phase transitions in monolayers and bilayers, in particular the hquid/gel transition. The chain length and chain architecture determine the efficiency of an amphiphile and thus influence the phase behavior. Moreover, they affect the shapes and size distributions of micelles. Chain models are usually fairly universal, in the sense that they can be used to study many different phenomena. 

R. G. Larson. Monte Carlo simulations of the phase behavior of surfactant solutions. J Phys II Erance 6 1441-1463, 1996. 

The cost/performance factor of individual surfactants will always be considered in determining which surfactants are blended in a mixed active formulation. However, with the recent advent of compact powders and concentrated liquids, other factors, such as processing, density, powder flowability, water content, stabilization of additives, dispersibility in nonaqueous solvents, dispersion of builders, and liquid crystalline phase behavior, have become important in determining the selection of individual surfactants. 

The phase behavior of a-ester sulfonates has been studied in detail with methyl laurate and methyl palmitate [58]. In both cases, at higher temperatures, as the surfactant concentration increases, there is a transition from an isotropic solution to a hexagonal liquid crystalline phase and finally, at high surfactant concentrations, to a lamellar liquid crystal (Fig. 4). The crystal/liquid-crys-tal phase transition occurs at even higher temperatures as the chain length increases. On the other hand, chain length has practically no influence on the... 

Micellar flooding is a promising tertiary oil-recovery method, perhaps the only method that has been shown to be successful in the field for depleted light oil reservoirs. As a tertiary recovery method, the micellar flooding process has desirable features of several chemical methods (e.g., miscible-type displacement) and is less susceptible to some of the drawbacks of chemical methods, such as adsorption. It has been shown that a suitable preflush can considerably curtail the surfactant loss to the rock matrix. In addition, the use of multiple micellar solutions, selected on the basis of phase behavior, can increase oil recovery with respect to the amount of surfactant, in comparison with a single solution. Laboratory tests showed that oil recovery-to-slug volume ratios as high as 15 can be achieved [439]. 

The performance of demulsifiers can be predicted by the relationship between the film pressure of the demulsifier and the normalized area and the solvent properties of the demulsifier [1632]. The surfactant activity of the demulsifier is dependent on the bulk phase behavior of the chemical when dispersed in the crude oil emulsions. This behavior can be monitored by determining the demulsifier pressure-area isotherms for adsorption at the crude oil-water interface. 

Furthermore, the experimental difficulties of studying phase behavior can be greatly compounded when surfactants are added to a system of oil and/or C02 and water, because the surfactant system often... 

Fig. 4.4 Phase behavior of the polyoxyethylene alcohol Cn2E3 and detergency, 2 g/L surfactant [44].

Hill, R. M. Li, X. Davis, H. T. Ternary Phase Behavior of Mixtures of Siloxane Surfactants, Silicone Oils, and Water. In Silicone Surfactants-, Hill, R. M., Ed. Surfactant Science Series Dekker New York, 1999 Vol. 86, Chapter 12, pp 314-348. 

The procedure consists of three steps. The first step is to identify all the desired product quality factors or attributes for the new product. Then what follows is the selection of the appropriate product form and microstructure, a stable surfactant system with the right performance based on phase behavior, and the appropriate active ingredients in order to realize those quality factors previously identified. Finally the process flowsheet will be created with the equipment units and process operating conditions determined. 

Li H, Hao J (2007) Phase behavior of salt-free catanionic surfactant aqueous solutions with fullerene C60 solubilized. J Phys Chem B. Ill 7719-7724. 

The most frequent emulsiflcation using phase inversion is known as the PIT (Phase Inversion Temperature) method [81-83] and occurs through a temperature quench. This method is based on the phase behavior of nonionic surfactants and the correlation existing between the so-called surfactant spontaneous curvature and the type of emulsion obtained. 

K. Thalberg, B. Lindman, and G. Karlstrom Phase Behavior of Cationic Surfactant and Anionic Polyelectrolyte Influence of Surfactant Chain Length and Polyelectrolyte Molecular Weight. J. Phys. Chem. 95, 3370 (1991). 

R Hansson and M. Akngren Interaction of Alkyltrimethylammonium Surfactants with Polyacrylate and Poly(Styrenesulfonate) in Aqueous Solution Phase Behavior and Surfactant Aggregation Numbers. Langmuir 10, 2115 (1994). 

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