Surfactant interfacial properties

Pashley R M and Israelachvili J N 1981 A comparison of surface forces and interfacial properties of mica in purified surfactant solutions Colloids Surf. 2 169-87... 

The influence of amphiphiles on interfacial properties interfacial tension, wetting behavior, dynamical aspects such as the question of how small amounts of surfactant influence the kinetics of phase separation. 

Chemical EOR methods are based on the injection of chemicals to develop fluid or interfacial properties that favor oil production. The three most common of these methods are polymer flooding, alkaline flooding, and surfactant flooding. 

The recovery of petroleum from sandstone and the release of kerogen from oil shale and tar sands both depend strongly on the microstmcture and surface properties of these porous media. The interfacial properties of complex liquid agents—mixtures of polymers and surfactants—are critical to viscosity control in tertiary oil recovery and to the comminution of minerals and coal. The corrosion and wear of mechanical parts are influenced by the composition and stmcture of metal surfaces, as well as by the interaction of lubricants with these surfaces. Microstmcture and surface properties are vitally important to both the performance of electrodes in electrochemical processes and the effectiveness of catalysts. Advances in synthetic chemistry are opening the door to the design of zeolites and layered compounds with tightly specified properties to provide the desired catalytic activity and separation selectivity. 

The area of colloids, surfactants, and fluid interfaces is large in scope. It encompasses all fluid-fluid and fluid-solid systems in which interfacial properties play a dominant role in determining the behavior of the overall system. Such systems are often characterized by large surface-to-volume ratios (e.g., thin films, sols, and foams) and by the formation of macroscopic assembhes of molecules (e.g., colloids, micelles, vesicles, and Langmuir-Blodgett films). The peculiar properties of the interfaces in such media give rise to these otherwise unlikely (and often inherently unstable) structures. 

Alkaline agents can reduce surfactant losses and permit the use of low concentrations of surfactants. Laboratory tests show that alkali and synthetic surfactants produce interfacial properties that are more favorable for increased oil mobilization than either alkali or surfactant alone [639,640]. 

Both nonionic and anionic surfactants have been evaluated in this application (488,489) including internal olefin sulfonates (487, 490), linear alkylxylene sulfonates (490), petroleum sulfonates (491), alcohol ethoxysulfates (487,489,492). Ethoxylated alcohols have been added to some anionic surfactant formulations to improve interfacial properties (486). The use of water thickening polymers, either xanthan or polyacrylamide to reduce injected fluid mobility mobility has been proposed for both alkaline flooding (493) and surfactant enhanced alkaline flooding (492). Crosslinked polymers have been used to increase volumetric sweep efficiency of surfactant - polymer - alkaline agent formulations (493). 

Xia J. et alii, "Effects of Different Distributions of Lyophobic Chain Length on the Interfacial Properties of Nonaethoxylated Fatty Alcohol" in "Phenomena in Mixed Surfactant Systems", J.F. Scamehom, Ed. 1986, ACS Stmposium Series 311, Wash. 

Only few attempts have been made recently to study the influence of the spacer between the silicone backbone and the hydrophilic head group on the interfacial properties of silicone surfactants [1,2,3]. Further the strong dispersion interactions caused by cyclic hydrocarbon sUuctures, especially the dicyclopentadienyl unit [4] have never been recognized to be an effective tool to counterbalance the known reverse effect of the methyl groups of the siloxanyl unit in coventional silicone surfactants. 

The basis for the foam properties is given by interfacial parameters. Although correlations have been shown between a single parameter and foam properties, there is still a lack in a general correlation between interfacial properties and the foam behavior of complex systems in detergency. The simplest approach to correlate interfacial parameters to foam properties is the comparison of the surface activity measured by the surface tension of a surfactant system and foam stability. 

Alkyl ether sulfates are/after alkyl benzene sulfonates(LAS),the group of technically important anionic surfactants with the largest production voluJne and product value. They have in comparison with other anionic surfactants special properties which are based on the particular structure of the molecule. These are expressed,for example,in the general adsorption properties at different interfaces, and in the Krafft-Point. Alkyl ether sulfates may be used under conditions, at which the utilization of other surfactant classes is very limited. They possess particularly favorable interfacial and application properties in mixtures with other surfactants. The paper gives a review of all important mechanisms of action and properties of interest for application. 

In application-related problems the question may also be formulated in terms of minimizing the necessary additional work. From knowledge of the interfacial properties of surfactant mixtures the surface activity, tendency to form micelles, adsorption, etc., can be increased. The following effects may pertain ... 

Degraded TBP process solvent is typically cleaned by washing with sodium carbonate or sodium hydroxide solutions, or both. Such washes eliminate retained uranium and plutonium as well as HDBP and H2MBP. Part of the low-molecular-weight neutral molecules such as butanol and nitrobutane, entrained in the aqueous phase, and 90-95% of the fission products ruthenium and zirconium are also removed by the alkaline washes. Alkaline washing is not sufficient, however, to completely restore the interfacial properties of the TBP solvent, because some surfactants still remain in the organic phase. 

Ionic surfactants are electrolytes dissociated in water, forming an electrical double layer consisting of counterions and co-ions at the interface. The Gouy-Chapman theory is used to model the double layer. In conjunction with the Gibbs adsorption equation and the equations of state, the theory allows the surfactant adsorption and the related interfacial properties to be determined [9,10] (The Gibbs adsorption model is certainly simpler than the Butler-Lucassen-Reynders model for this case.). 

During the past few years, the determination of the interfacial properties of binary mixtures of surfactants has been an area in which there has been considerable activity on the part of a number of investigators, both in industry and in academia. The Interest in this area stems from the fact that mixtures of two different types of surfactants often have interfacial properties that are better than those of the individual surfactants by themselves. For example, mixtures of two different surface-active components sometimes reduce the interfacial tension at the hydrocarbon/water interface to values far lower than that obtained with the individual surfactants, and certain mixtures of surfactants are better foaming agents than the individual components. For the purpose of this discussion we define synergism as existing in a system when a given property of the mixture can reach a more desirable value than that attainable by either surface-active component of the mixture by itself. 

Rouimi, S., Schorsch, C., Valentini, C., Vaslin, S. (2005). Foam stability and interfacial properties of milk protein-surfactant systems. Food Hydrocolloids, 19, 467 178. 

Surface properties of proteins in general, 296-298 (table) purification methods based on, 272 Surface tension and interfacial properties, 609-628. see also Interfaces Surfactants, see also Interfacial tension definition and adsorption kinetics of, 617-618, 639... 

Vol. 13 Surfactants Chemistry, Interfacial Properties, Applications. Edited by V.B. Fainerman, D. Miibius and R. Miller... 

Example In flotation, for a solid particle to float on a liquid surface, the upward pull of the meniscus around it (reflected in 6) must at least balance the weight of the particle. Any natural tendency of the particles to float or not float, depending on 6, can be modified by adding oils or surfactants to alter the interfacial properties. A mineral particle that does not float (Case 1) can be floated by adding surfactant (Case 2) as follows. 

Detergency involves the action of surfactants to alter interfacial properties and to reduce the energy needed to cause the removal of dirt from solid surfaces. In addi-... 

The use of copolymers as surfactants is widespread in macromolecular chemistry in order to compatibilize immiscible blends. These additives are sometimes named surfactants , interfacial agents or more usually compatibi-lizers . Their effect on improving different properties is observed interfacial tension and domain size decrease, while there is an increase in adhesion between the two phases and a post-mixing morphology stabilization (coalescence prevention). The aim of the addition of such copolymers is to obtain thermodynamically stable blends, but the influence of kinetic parameters has to be kept in mind as long as they have to be mastered to reach the equilibrium. Introducing a copolymer can be achieved either by addition of a pre-synthesized copolymer or by in-situ surfactant synthesis via a fitted re-... 

Interfacial Properties, Dispersion and Phase Behavior, and Surfactant Design... 

Other surfactant physical properties and performance parameters such as critical micelle concentration, cloud point, and interfacial tension may be related to surfactant chemical structure using multiple correlation analysis. 

The formation of bicontinuous microemulsions is conditioned by the nature of the monomer which is present in large amounts (up to by weight and which e.terts a great effect on the HLB and interfacial properties of the systems. Furthermore as the polynerirable microemulsicns contain a fairly large concentration of surfactant(s), interactions between surfactants and monomers cannot be neglected, especially when the latter are electrolytes. 

Addition of salting-out type electrolytes to oil-water-surfactant (s) systems has also a strong influence on their phase equilibria and interfacial properties. This addition produces a dehydration of the surfactant and its progressive transfer to the oil phase (2). At low salinity, a water-continuous microemulsion is observed in equilibrium with an organic phase. At high salinity an oil-continuous microemulsion is in equilibrium with an aqueous phase. At intermediate salinity, a middle phase microemulsion with a bicontinuous structure coexists with pure aqueous and organic phases. These equilibria were referred by Vinsor as Types I,II and III (33). 

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