Effect on surfactant

Acid flooding can be successful in formations that are dissolvable in the particular acid mixture, thus opening the pores. Hydrochloric acid is common, in a concentration of 6% to 30%, sometimes also with hydrofluoric acid and surfactants added (e.g., isononylphenol) [130,723]. The acidic environment has still another effect on surfactants. It converts the sulfonates into sulfonic acid, which has a lower interfacial tension with oil. Therefore a higher oil forcing-out efficiency than from neutral aqueous solution of sulfonates is obtained. Cyclic injection can be applied [4,494], and sulfuric acid has been described for acid treatment [25,26,1535]. Injecting additional aqueous lignosulfonate increases the efficiency of a sulfuric acid treatment [1798]. 

The presence of a pre-adsorbed nonionic polymer has almost negligible effects on surfactant adsorption except at high surfactant concentrations where surfactant adsorption is reduced. 

Solubilization of water. Detergency is defined as the ability of surfactant molecules to solubilize water molecules or polar substances in soft-core and hardcore RMs. Thus, micellization and solubilization are competitive processes. Any solubilized probe molecule causes a decrease in the CMC. Solubilization describes the dissolution of a solid, liquid or gas by an interaction with surfactant molecules. Addition of water has a dramatic effect on surfactant aggregation in hydrocarbons because hydrogen bonding has an appreciable stabilizing effect on reverse micelles. Solubilization for reverse micelles is phenomenologically similar to the adsorption processes (Eicke and Christen, 1978 Kitahara, 1980 Kitahara et al., 1976 Singleterry, 1955). 

Leontidis, E. Hofmeister anion effects on surfactant self-assembly and the formation of mesoporous solids. Curr. Opin. Colloid Interface Sci. 2002, 7 (1-2), 81-91. 

Surface area of the porous media has a remarkable effect on surfactant adsorption. Liu (2007) measured surfactant adsorption in three rock samples of the same carbonate porous medium but with different surface areas. He used a TC blend surfactant—1 1 mixture by weight of dodecyl 3 ethoxylated sulfate and iso-tridecyl 4 propoxylated sulfate from Stepan. He found that the adsorptions of the TC blend on the three samples were close to each other if the adsorption was calculated by using surfactant adsorption amount per porous media surface area, as shown in Figure 7.43. However, if the adsorption was... 

The uptake of water to form liquid crystal has pronounced effects on surfactant molecular motion and intermolecular geometry. The aliphatic carbons near the chain ends move with considerable freedom and give sharp nmr peaks whereas motions in the benzene ring and its proximity on the chain are severely restricted and give peaks too broad to be observed. 

ALKALI EFFECTS ON SURFACTANT RETENTION IN BEREA SANDSTONE ... 

Pressure effects on surfactant systems containing conventional liquid alkanes have not often been studied because of the very low compressibility of liquids. Conflicting results have been reported [38-40]. It is likely that the changes in cohesive energy density (solubility parameter) of the phases over the pressure ranges used were too low to produce definitive trends in phase behavior. The solubility parameter of compressed liquid propane, however, is moderately adjustable with pressure, and therefore a propane-brine-AOT system could be expected to show pressure-driven phase transitions [20,22,41]. 

IV. ALKANE CARBON NUMBER EFFECTS ON SURFACTANT PHASE BEHAVIOR... 

Several objectives motivated the extension of ACN studies to light compressible solvents [12]. Initial studies of AOT in such solvents had demonstrated the possibility of intriguing solvent effects [20,21,32], which could be clarified by additional experiments. A second objective was to test the concepts generated from the thermodynamic models that were developed for the AOT-brine-propane system [25,44]. A final objective was to study the behavior of nonionic surfactant systems as a complement to AOT systems. Nonionic systems provide an enhanced opportunity to study temperature effects on surfactant phase behavior, as nonionic surfactants are much more responsive to temperature than the anionic surfactant AOT. 

The potential importance of the temperature effect on surfactant properties has been recognized for some time and led to the concept of using the PIT as a quantitative tool for the evaluation of surfactants in emulsion systems. As a general procedure, emulsions of oil, aqueous phase, and approximately 5% surfactant were prepared by shaking at various temperatures. The temperature at which the emulsion was found to be inverted from o/w to w/o (or vice versa) was then defined as the PIT of the system. Since the effect of temperature on the solubility of nonionic surfactants is reasonably well understood, the physical principles underlying the PIT phenomenon follow directly. 

A. Berthod, I. Girard and C. Gonnet, Additive Effects on Surfactant Adsorption and Ionic Solute Retention in MLC, Anal Chem., 58 1362 (1986). 

Using a mouse lung epithelial cell line, Grummer and Zachman (1998) explored retinoic acid-dexa-methasone interactions through the study of retinoic acid and dexamethasone effects on retinoic acid receptor and surfactant protein C mRNA expression. Retinoic acid increased expression of retinoic acid receptor-P (5.5 times) and surfactant protein C (2 times) mRNA, with maximal effects at 24 h and at 10" M. The retinoic acid induction was not inhibited by cycloheximide, suggesting retinoic acid affects transcription. With addition of actino-mycin D, retinoic acid did not affect the disappearance rate of retinoic acid receptor-P mRNA, but surfactant protein C mRNA degradation was slowed, indicating an effect on surfactant protein C mRNA stability. 

Figure 29 Effect on surfactant micelle morphology by addition of a hydrophobically modified associative polymer.

Several references were made above to the term phase inversion temperature. With the exceptions of Eqs. (9.17) and (9.18), however, no specific reference was made to the effect of temperature on the HLB of a surfactant. From the discussions in Chapter 4, it is clear that temperature can play a role in determining the surface activity of a surfactant, especially nonionic amphiphiles in which hydration is the principal mechanism of solubilization. The importance of temperature effects on surfactant solution properties, especially the solubility or cloud point of nonionic surfactants, led to the evolution of the concept of using that property as a tool for predicting the activity of such materials in emulsions. Since the cloud point is defined as the temperature, or temperature range, at which a given amphiphile loses sufficient solubility in water to produce a normal surfactant solution, it was assumed that such a temperature-driven transition would also be reflected in the role of the surfactant in emulsion formation and stabilization. 

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