Oils, surfactants

Microemulsion Polymerization. Polyacrylamide microemulsions are low viscosity, non settling, clear, thermodynamically stable water-in-od emulsions with particle sizes less than about 100 nm (98—100). They were developed to try to overcome the inherent settling problems of the larger particle size, conventional inverse emulsion polyacrylamides. To achieve the smaller microemulsion particle size, increased surfactant levels are required, making this system more expensive than inverse emulsions. Acrylamide microemulsions form spontaneously when the correct combinations and types of oils, surfactants, and aqueous monomer solutions are combined. Consequendy, no homogenization is required. Polymerization of acrylamide microemulsions is conducted similarly to conventional acrylamide inverse emulsions. To date, polyacrylamide microemulsions have not been commercialized, although work has continued in an effort to exploit the unique features of this technology (100). 

Waste aqueous metalworking fluids may be successfully treated by conventional means for removal of tramp oil, surfactants, and other chemical agents to provide suitable effluent water quaUty (78). 

Natural Ethoxylated Fats, Oils, and Waxes. Castor oil (qv) is a triglyceride high in ticinoleic esters. Ethoxylation in the presence of an alkaline catalyst to a polyoxyethylene content of 60—70 wt % yields water-soluble surfactants (Table 20). Because alkaline catalysts also effect transestenfication, ethoxylated castor oil surfactants are complex mixtures with components resulting from transesterrfication and subsequent ethoxylation at the available hydroxyl groups. The ethoxylates are pale amber Hquids of specific gravity just above 1.0 at room temperature. They are hydrophilic emulsifiers, dispersants, lubricants, and solubilizers used as textile additives and finishing agents, as well as in paper (qv) and leather (qv) manufacture. 

Formulations for one-shot polyether systems are similar to those used for flexible foams and contain polyether, isocyanate, catalyst, surfactant and water. Trichloroethyl phosphate is also often used as a flame retardant. As with polyesters, diphenylmethane di-isocyanate is usually preferred to TDI because of its lower volatility. Tertiary amines and organo-tin catalysts are used as with the flexible foams but not necessarily in combination. Silicone oil surfactants are again found to be good foam stabilisers. Volatile liquids such as trichlorofluoro-methane have been widely used as supplementary blowing agents and give products of low density and of very low thermal conductivity. 

Presents a global forum for the science and technology of fats, oils, surfactants, and related materials. 

Because this is less than 1 mN/m, extremely low oil-surfactant solution surface tensions are necessary. 

Different methods are used in microemulsion formation a low-energy emulsification method by dilution of an oil surfactant mixture with water and dilution of a water-surfactant mixture with oil and mixing all the components together in the final composition. These methods involve the spontaneous formation of microemulsions and the order of ingredient addition may determine the formation of the microemulsion. Such applications have been performed with lutein and lutein esters. ... 

High pressure homogenization may also be used to form microemulsions but the process of emulsification is generally inefficient (due to the dissipation of heat) and extremely limited as the water-oil-surfactant mixture may be highly viscous prior to microemulsion formation. ... 

K. A. Barsukov, V. Yu. Ismikhanov, A. A. Akhmetov, G. S. Pop, G. A. Lanchakov, and V. M. Sidorenko. Composition for hydro-bursting of oil and gas strata—consists of hydrocarbon phase, sludge from production of sulphonate additives to lubricating oils, surfactant-emulsifier and minerdised water. Patent SU 1794082-A, 1993. 

Intermixing of the polymer mobility control fluid with the surfactant slug can result in surfactant - polymer interactions which have a significant effect on oil recovery (476). Of course, oil - surfactant interactions have a major effect on interfacial behavior and oil displacement efficiency. The effect of petroleum composition on oil solubilization by surfactants has been the subject of extensive study (477). 

Phase Inversion The phase inversion of brine/oil/surfactant systems was established routinely by measuring solution conductivity employing a Jenway FWA 1 meter and cell. The process identifies the range over which a large decrease in conductivity occurs as the sytem under test is converted from an oil in water emulsion to a water in oil emulsion. Phase... 

The formation of ethylcellulose nanoemulsions by a low-energy method for nanoparticle preparation was reported recently. The nanoemulsions were obtained in a water-polyoxyethylene 4 sorbitan monolaurate-ethylcellulose solution system by the PIC method at 25 °C [54]. The solvent chosen for the preparation of the ethylcellulose solution was ethyl acetate, which is classed as a solvent with low toxic potential (Class 3) by ICH Guidelines [78]. Oil/water (O/W) nanoemulsions were formed at oil/ surfactant (O/S) ratios between 30 70 and 70 30 and water contents above 40 wt% (Figure 6.1). Compared with other nanoemulsions prepared by the same method, the O/S ratios at which they are formed are high, that is, the amount of surfactant needed for nanoemulsion preparation is rather low [14]. For further studies, compositions with volatile organic compound (VOC) contents below 7 wt% and surfactant concentrations between 3 and 5 wt% were chosen, that is, nanoemulsions with a constant water content of 90% and O/S ratios from 50 50 to 70 30. 

Phase inversion along the dilution path (by addition of water to the oil/surfactant mixture) followed for nanoemulsion preparation was confirmed by conductivity measurements, and was found to be essential for obtaining finely dispersed systems, as transparent dispersions were not obtained if the order of addition of the components was changed following an experimental path with no phase inversion (Figure 6.2). 

A microemulsion droplet is a multicomponent system containing oil, surfactant, cosurfactant, and probably water therefore there may be considerable variation in size and shape depending upon the overall composition. The packing constraints which dictate size and shape of normal micelles (Section 1) should be relaxed in microemulsions because of the presence of cosurfactant and oil. However, it is possible to draw analogies between the behavior of micelles and microemulsion droplets, at least in the more aqueous media. 

A Proposed Theory. In earlier publications (1-3), a theory was proposed to correlate solubilization rate, interfacial tension and size of the surfactant aggregate (1) the interfacial tension lowering between the oil-surfactant solution interface is a function of the rate of solubilization of oil, and (2) the rate of solubilization (AS/At) is a function of the effective volume for solubilization ... 

If one considers a system consisting of water (with or without added electrolyte) + oil + surfactant (with or without a cosurfactant) at equilibrium, there will most likely be present more than two phases (due to the formation of emulsion or microemulsion). The determination of the interfacial tension, Yij> between the two liquid phases is, therefore, of much importance, in order to understand the forces which stabilize these emulsions or microemulsions. The interfacial tension can be measured by using a variety of methods, as described in detail in surface chemistry text-books (1-3). If the magnitude of yij is of the order of few mN/m (=dyne/ cm), then the methods generally used are Wilhelmy plate method or the drop volume (or weight) method (1-4). However, in certain systems ultra-low (or low) interfacial tensions have been reported. Since these low values are reported to be essential in order to mo-... 

A microemulsion is defined as a thermodynamically stable and clear isotropic mixture of water-oil-surfactant-cosurfactant (in most systems, it is a mixture of short-chain alcohols). The cosurfactant is the fourth component, which effects the formation of very small aggregates or drops that make the microemulsion almost clear. 

Microemulsions are also characterized as microstructured, themodynamically stable mixtures of water, oil, surfactant, and additional components (such as cosurfactants). The study of microemulsions has shown that they are of the following types ... 

Microemulsions are thermodynamically stable mixtures. The interfacial tension is almost zero. The size of drops is very small, and this makes the microemulsions look clear. It has been suggested that microemulsion may consists of bicontinuous structures, which sounds more plausible in these four-component microemulsion systems. It has also been suggested that microemulsion may be compared to swollen micelles (i.e., if one solubilizes oil in micelles). In such isotropic mixtures, short-range order exists between droplets. As found from extensive experiments, not all mixtures of water-oil-surfactant-cosurfactant produce a microemulsion. This has led to studies that have attempted to predict the molecular relationship. 

The phase diagram of the water-oil-surfactant (and cosurfactant) needs to be determined. 

The modification of the sand surface allows the grains to simultaneously adsorb soluble heavy metals and remove particulate metals by filtration in a column packed with the media. Important factors to the performance of the adsorbent include pH of the solution to be treated, empty bed detention time (EBDT), and the presence of complexing agents, oil, surfactant, and biodegradable substances. 

Pierlot C, Poprawski J, Catte M, Salager JL, Aubry JM (2003) Experimental design for the determination of the physicochemical parameters of optimum water-oil surfactant systems. Polym Int 52 614-618... 

The possible strnctnres which can be formed by a mixtnre of hydrocarbon oil, surfactant and water is illnstrated below in Fignre 5.2. The variation and complexity of these strnctnres has led to mnch research on potential indnstrial applications from tertiary oil recovery to enhanced drng delivery systems. Many of the strnctnres can be predicted using models based on the optimal cnrvatnre of the interface, not nnlike that nsed to predict snrfactant aggregation. 

Equilibrium Phase Behaviour. Phase studies were performed using approximately 10 g samples of oil-surfactant mixture diluted sequentially by the weighed addition of water. The initial binary mixture contained 5-70 w/w surfactant at 5 intervals. Phase boundaries were determined to + 0.5 water. The ternary mixtures in Pyrex glass tubes fitted with PTFE lined caps were equilibrated to the required temperature (20-65 0.1°C) for 2 hours and then thoroughly mixed for 5 minutes using a Fisons orbitsil whirlimixer. The tubes were then returned to the waterbath and left undisturbed for 48 hours before identification of the phase type using a crossed polarised viewer and an optical microscope. 

Groves (1978) provided an intuitive explanation based on a mechanical model in which water penetrates into the oil/surfactant system, forming liquid crystals but, more to the point, considerably expanding the interface. This is the reason why it is necessary to postulate that water is inconsiderable excess. The surface expands so that instead of a negative interfacial tension what we have is a positive surface pressure. At this point it is not unreasonable to visualize the surface expanding and stranding as postulated in the Gopal model. 

This product is an aqueous solution of water-soluble vitamins with oily vitamin A palmitate and cholecalceferol solubilized in water using the surfactant system of Tween 80 and Cetomacrogol. This syrup is a solubilized oil surfactant system and is liable to heat and rate of mixing. The temperature of solution must not exceed 30°C at the time of final mixing. The final mixing must be in continuous manner without any interruption. For the preparation of oily phase, the container must be dry. 

Combine pine oil, surfactants and IPA. Mix until clear. Add water slowly while under agitation. Mix until clear. 

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