Emulsification and Solubilization

When the concentration of surfactant is above a critical micelle concentration (CMC), two phenomena occur solubilization and emulsification. The former... 

Uddin, M.H., Kanei, N., and Kunieda, H. (2000) Solubilization and emulsification of perfume in discontinuous cubic phase. Langmuir, 16, 6891-6897. 

Clear evidence exists that solubilization and emulsification are major factors in removal of oily soils from hydn hobic, synthetic fabrics. Unlike roll-up, in which die interaction of die fribric widi the oily soil and water is the most critical factor, the solubilization-emulsification mechanism occurs primarily at the oil/ detergent solution interface and is therefore directly influenced by the phase behavior of the cmre nding oil-water-surfiictant system. 

Uses Surfactant for industrial, agrochem., and textile applies. solubilizer and emulsifer for polar substrates emulsifier for creams, lotions solubilizer for topical pharmaceuticals and shampoos... 

Once the soil has been separated from the substrate, it is necessary to prevent its redeposition until it is removed in the rinsing process. There are two general mechanisms for the isolation of oily soils from the substrate micellar solubilization and emulsification. The solubilization of oily materials in surfactant micelles is probably the most important mechanism for the removal of oily soil from substrates and follows the general tendencies outlined in Chapter 6. It has generally been observed that oily soil removal from textile surfaces becomes significant only above the cmc for nonionic surfactants, and even for some anionic materials with low erne s. Removal efficiency reaches a maximum at several times that concentration. Since the adsorption of surfactants at interfaces involves the monomeric, rather than the micellar form, while solubilization involves only the micellar form, those results would appear to indicate that in these cases, solubilization is... 

Surfactants are frequently used in detergents and food products to alter the properties of solution interfaces, mediating between immiscible phases because of their hydrophobic and hydrophilic moieties. The addition of surfactants increases the concentration of hydrophobic compounds in the water phase by solubilization or emulsification above a specific threshold, the critical micellar concentration (CMC), where surfactant molecules aggregate to micelles [130]. Two widely utilized nonionic surfactants, Tween 80 and Triton X-100, were evaluated in terms of enzyme interaction, by calculating the inactivation coefficient (kA) under static conditions. Concentrations lower than CMC were studied in order to avoid diffusional limitations in the interaction of the enzyme and the PAH in the micellar phase. The concentration 0.25 CMC was considered the most favorable for the enzyme, with Triton X-100 being the surfactant that led to the lowest inactivation coefficients for all the concentrations tested and was 2.5 times lower than kd in control experiment. 

When a surfactant-water or surfactant-brine mixture is carefully contacted with oil in the absence of flow, bulk diffusion and, in some cases, adsorption-desorption or phase transformation kinetics dictate the way in which the equilibrium state is approached and the time required to reach it. Nonequilibrium behavior in such systems is of interest in connection with certain enhanced oil recovery processes where surfactant-brine mixtures are injected into underground formations to diplace globules of oil trapped in the porous rock structure. Indications exist that recovery efficiency can be affected by the extent of equilibration between phases and by the type of nonequilibrium phenomena which occur (J ). In detergency also, the rate and manner of oily soil removal by solubilization and "complexing" or "emulsification" mechanisms are controlled by diffusion and phase transformation kinetics (2-2). 

Surfactants were one excipient family which required reevaluation in HFAs. Surfactants are used in MDIs for several reasons seal lubrication, emulsification, dispersion, solubilization, and as a preservative. Surfactants used in GFG formulations such as lecithin, sorbitan trioleate, soya lecithin, and oleic acid are highly soluble in GFG propellants (particularly GFG 11), however in HFA propellants, the solubility of these surfactants is relatively poor. Several authors point out that surfactant polarity, indicated by their respective hydrophilic-lipophilic balance (HLB) correlates with the incompatibility of the aforementioned surfactants... 

Winsor, P.A., 1948. Hydrotropy, solubilization and related emulsification processes, part I. Trans. Faraday Soc. 44, 376-398. 

Liquid soil is usually removed by roll-up, emulsification, direct solubilization, and possibly formation of microemulsion or liquid crystalline phases. The oil emulsification capability of the surfactant solution and the oil-water interfacial tension are relevant physicochemical parameters. 

Figure 1. Emulsification phenomena in Salem crude oil-Petrostep 420 containing n-hexanol (a) solubilization and diffusion (b) development of interfacial film (c) presence of thick films around droplets (d) coalescence of srrudl droplets and (e) disintegration of interfacial film.

Retention in Porous Media. Anionic surfactants can be lost in porous media in a number of ways adsorption at the solid—liquid interface, adsorption at the gas—liquid interface, precipitation or phase-separation due to incompatibility of the surfactant and the reservoir brine (especially divalent ions), partitioning or solubilization of the surfactant into the oil phase, and emulsification of the aqueous phase (containing surfactant) into the oil. The adsorption of surfactant on reservoir rock has a major effect on foam propagation and is described in detail in Chapter 7 by Mannhardt and Novosad. Fortunately, adsorption in porous media tends to be, in general, less important at elevated temperatures 10, 11). The presence of ionic materials, however, lowers the solubility of the surfactant in the aqueous phase and tends to increase adsorption. The ability of cosurfactants to reduce the adsorption on reservoir materials by lowering the critical micelle concentration (CMC), and thus the monomer concentration, has been demonstrated (72,13). 

Bile fluid performs two important functions (1) the emulsification, solubilization, and transport of lipids and fat-soluble vitamins by the detergent effects of bile acids, and (2) the elimination of many waste products, including bilirubin and cholesterol secreted via the bile into the gastrointestinal tract. Bile acids and bile salts are the principal components of the bile fluid, acting as detergents in the digestion of fat in the intestinal tract. 

Unique specialty surfactant developed to solubilize and disperse heavy greases and oils. Uses include automotive engine degreasers, metal cleaners, oil spill cleanups, and heavy duty emulsification. Excellent emulsifier for agricultural formulations. 

The excellent ability of nonionics to solubilize and disperse hydrophobic soils such as fats, mineral oils, etc, in water leads to extensive use of this e of emulsifier. Their often superior detergency with respect to solids surfaces is due to a combination of relatively low critical micellar concentration (CMC), allowing emulsification to take place at low emulsifier concentrations, and an ability to adsorb hydrophobically to interfaces and thus, by steric repulsion forces, to disperse hydrophobic liquid or colloid matter. An important group of nonionic emulsifiers is based on ethoxylated alkyl alcohols. Increasing demands for biodegradability and low aquatic toxicity of degradation products of industrial chemicals is expected to make fatty alcohols ethoxylates and nonionic emulsifiers based on natural raw materials an even more important group of chemicals in the future. 

Uses Emulsifier for foods, cosmetics (shampoos, conditioners, bath prods., fragrance emulsif er), pharmaceuticals, household, and industrial applies. flavor solubilizer and dispersant o/w emulsifier, vise, modifier, wetting agent for household prods. lubricant and emulsifier in textile syn. fiber finish oils antifog in PVC anti-... 

Uses Surfactant, emulsifer, defoamer, wetting agent, solubilizer, and conditioner in antiperspirants, depilatories, creams, lotions, pigment dispersions, shampoos, detergents, bleaches, and dyes... 

Uses 0/w emulsifer, detergent, vise, builder, dispersant, emulsifier, solubilizer and wetting agent in creams, lotions, bath oils, antiperspirants, color cosmetics vise, builder in shampoos emulsifer for fatty alcohols (such as cetyl and stearyl alcohols) into creams/lotions in add stability to emulsions which contain Features Stable in acid and alkali ranges add stability to emulsions which contain ethanol compat. with a wide rage of anionic and cationic emulsifiers Properties Gardner 1 max. waxy wh. solid sol. (5% aq.) in water sp.gr. 1.04 m.p. 39 C HLB 15.5 acid no. 1 max. sapon. no. 2.0 max, hyd, no, 45-60 flash pt. (COC) > 175 C pH (3% aq.) 5.5-7.5 0.5% moisture Toxicology May cause eye irritation... 

Uses Surfactant, emollient, emulsifer, thickener, solubilizer, and superfatting agent for shampoos, foam baths, baby shampoos, pharmaceuticals anti-irritant for surfactants... 

Uses Emulsifer, solubilizer, and dispersant for cosmetics, pharmaceuticals, foods Features Hydrophilic Regulatory JSCI listed... 

Interactions between polymers and surfactants have been widely investigated in the recent decades. The interaction may lead to a polymer-surfactant complex formation, which may have a significant influence on the system properties e.g. emulsification, colloidal stability, viscosity enhancement, gel formation, solubilization, and phase separation [Goddard 1993a Goddard 2002]. The properties and structure of surfactant-polymer complexes depend on the molecular characteristics of both the polymer and surfactant [Lindman Thalberg,... 

Winsor, R A. (1948). Hydrotropy, solubilization, and related emulsification processes. I. Transactions of the Faraday Society, 44,376-382... 

The cleaning process proceeds by one of three primary mechanisms solubilization, emulsification, and roll-up [229]. In solubilization the oily phase partitions into surfactant micelles that desorb from the solid surface and diffuse into the bulk. As mentioned above, there is a body of theoretical work on solubilization [146, 147] and numerous experimental studies by a variety of spectroscopic techniques [143-145,230]. Emulsification involves the formation and removal of an emulsion at the oil-water interface the removal step may involve hydrodynamic as well as surface chemical forces. Emulsion formation is covered in Chapter XIV. In roll-up the surfactant reduces the contact angle of the liquid soil or the surface free energy of a solid particle aiding its detachment and subsequent removal by hydrodynamic forces. Adam and Stevenson s beautiful photographs illustrate roll-up of lanoline on wood fibers [231]. In order to achieve roll-up, one requires the surface free energies for soil detachment illustrated in Fig. XIII-14 to obey... 

Emulsification is the process by which a hydrophobic monomer, such as styrene, is dispersed into micelles and monomer droplets. A measure of a surfactant s abiUty to solubilize a monomer is its critical micelle concentration (CMC). Below the CMC the surfactant is dissolved ia the aqueous phase and does not serve to solubilize monomer. At and above the CMC the surfactant forms spherical micelles, usually 50 to 200 soap molecules per micelle. Many... 

Both mechanical and chemical action promote ink detachment from cellulose fibers during pulping. Mechanical action includes interfiber abrasion and fiber flexing and bending. Chemical action includes fiber swelling and surfactant-promoted ink particle emulsification and solubilization. 

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