Emulsion basic types

The carrier should not dissolve in the feed liquid or receptor phase in order to avoid leakage from the liquid membrane. In order to achieve sufficient selectivity, minimization of nonselective transport through the bulk of the membrane liquid is required. Liquid membranes can be divided into three basic types [6] emulsion supported and bulk liquid membranes, respectively (Fig. 5-2). 

An emulsion is a system consisting of a liquid dispersed as droplets in a second immiscible liquid, often stabilized by an emulsifying agent. In the oil field, the two basic types of emulsions are water-in-oil and oil-in-water oil-in-water emulsions are often termed reverse emulsions. More than 95% of the crude-oil emulsions formed in the oil field are of the water-in-oil type. Nonetheless, oil-in-water emulsions are receiving growing interest in pollution abatement as they are readily miscible with water. 

Parenteral dosage forms can be categorized as small-volume parenteral (SVP), large-volume parenteral (LVP), and lyophilized products. Three basic types of SVP formulations exist solution, suspension, and emulsion. The following aspects should be addressed to successfully formulate a parenteral dosage form (1) selection of a suitable vehicle (aqueous, co-solvent, or nonaqueous) (2) selection of formulation adjuvants, such as buffering agents. 

They are clear, stable, isotropic liquid mixtures of oil, water and surfactant, frequently in combination with a cosurfactant. The aqueous phase may contain salt(s) and/or other ingredients and the "oil" may actually be a complex mixture of different hydrocarbons and olefins. In contrast to ordinary emulsions, microemulsions form upon simple mixing of the components and do not require the high shear conditions generally used in the formation of ordinary emulsions. The two basic types of microemulsions are direct (oil dispersed in water, O/W) and reversed (water dispersed in oil, W/0). See emulsion. 

Emulsions can be found as two basic types, i.e., 0/W and W/O, but in some particular cases, multiple or double emulsions labeled Wj/0/W2 and Oj/W/02 also occur. The emulsion type may be determined by different methods. In most applications the aqueous phase contains one or various electrolytes, and thus conducts electricity somehow, whereas the oil or organic phase does not. Consequently, the measurement of electrolytic conductivity is a handy way to ascertain the emulsion type. Moreover, the continuous monitoring of the electrolytic conductivity allows the determination of the change in emulsion type which is referred to as emulsion inversion. 

There are three basic categories of adhesive bonding used, each requiring specific equipment. Selection of a particular technique depends on the nature of the substrates used and final application. There are a considerable number of adhesive laminating materials and techniques or variants upon the theme, but it can be reduced to the three basic types of material, aqueous based (see Emulsion and dispersion adhesives), Soivent-based adhesives, solventless 100% solids or Hot melt adhesives, and to the two basic techniques, wet and dry lamination. 

There are two basic types of emulsions envisioned by the current HLB system. They are oil in water (O/W) and water in oil (W/O). The phase listed first is the discontinuous phase. That is, it is the phase that is emulsified into the other. Upon mixing of the two phases with a surfactant present, the emulsifier forms a third phase as a film at the interface between the two phases being mixed together. It is also predicted that the phase in which the emulsifier is most soluble will become the continuous phase. The continuous phase need not be the predominant quantity of material present. There are emulsions where the discontinuous phase makes up a greater weight percent than the continuous phase. A simple test is if the emulsion is readily diluted with water, water is the continuous phase. 

Formulations. Emulsion breakers and inhibitors are formulated to break water-in-oil emulsions or to prevent them from forming. Some information is available on specific formulations of these agents, but the formulations vary extensively and many are not specifically patented. Several basic types of formulations are ... 

This paper reviews the use of emulsions and microemulsions as liquid membranes with sp ial emphasis placed on the separation of mercury, as Hg(N03)2, from water using oleic acid as the extractant Although emulsion (either macro- or micro-) liquid membranes offer advantages in terms of fast rates of separation, new modes of creating a stabilized liquid membrane utilizing hollow fiber contactors offer comparable flux in a more stable format. The paper wiU start with a review of the basic types of liquid membranes as currently used in research. The discussion will then focus on the author s experience with emulsified liquid membrane systems. The last section of the paper will discuss the obvious next step in liquid membrane technology, the use of emulsion liquid membranes in hollow fiber contactors. 

The basic types of emulsions are oil in water (o/w) emulsions, where oil droplets are dispersed in a continuous aqueous phase and water in oil (w/o) emulsions containing water droplets dispersed in oil (Figure 13.1). By dispersing an emulsion into a further continuous phase, a multiple or double emulsion can be obtained. A w/o emulsion dispersed into a second water phase leads to an water in oil in water (w/o/w) emulsion, whereas an o/w emulsion can be used to produce an oil in water in oil (o/w/o) emulsion by dispersing it into oil. 

There are three basic types of microemulsions, viz., direct (oil dispersed in water, denoted by o/w ), reversed or inverse (water dispersed in oil, denoted by w/o ), and bicontinuous (i.e., regions of water and oil). The domains of the dispersed phase are either globular or interconnected (giving a bicontinuous microemulsion), as shown schematically in Fig. 3.1. These are stabilized by an interfacial film of surfactant (usually in combination with a cosurfactant), its molecules being oriented at the interface such that the hydrophilic ends are in the aqueous phase and the hydrophobic ends are in the oil phase. It may be mentioned that the term microemulsion was first used by Hoar and Shuhnan [2], professors of chemistry at Cambridge University in 1943. However, other names are often used, such as transparent emulsion (implying optical clarity), micellar solution, and solubilized oil. 

Synthetic. The main types of elastomeric polymers commercially available in latex form from emulsion polymerization are butadiene—styrene, butadiene—acrylonitrile, and chloroprene (neoprene). There are also a number of specialty latices that contain polymers that are basically variations of the above polymers, eg, those to which a third monomer has been added to provide a polymer that performs a specific function. The most important of these are products that contain either a basic, eg, vinylpyridine, or an acidic monomer, eg, methacrylic acid. These latices are specifically designed for tire cord solutioning, papercoating, and carpet back-sizing. 

When the problem is to disrupt Ughtly bonded clusters or agglomerates, a new aspect of fine grinding enters. This may be iUustrated by the breakdown of pigments to incorporate them in liquid vehicles in the making of paints, and the disruption of biological cells to release soluble produces. Purees, food pastes, pulps, and the like are processed by this type of mill. Dispersion is also associated with the formation of emulsions which are basically two-fluid systems. Syrups, sauces, milk, ointments, creams, lotions, and asphalt and water-paint emulsions are in this categoiy. 

Mineral Oil Hydraulic Fluids and Polyalphaolefin Hydraulic Fluids. Limited information about environmentally important physical and chemical properties is available for the mineral oil and water-in-oil emulsion hydraulic fluid products and components is presented in Tables 3-4, 3-5, and 3-7. Much of the available trade literature emphasizes properties desirable for the commercial end uses of the products as hydraulic fluids rather than the physical constants most useful in fate and transport analysis. Since the products are typically mixtures, the chief value of the trade literature is to identify specific chemical components, generally various petroleum hydrocarbons. Additional information on the properties of the various mineral oil formulations would make it easier to distinguish the toxicity and environmental effects and to trace the site contaminant s fate based on levels of distinguishing components. Improved information is especially needed on additives, some of which may be of more environmental and public health concern than the hydrocarbons that comprise the bulk of the mineral oil hydraulic fluids by weight. For the polyalphaolefin hydraulic fluids, basic physical and chemical properties related to assessing environmental fate and exposure risks are essentially unknown. Additional information for these types of hydraulic fluids is clearly needed. 

Perhaps the most common particle type used for bioapplications is the polymeric microsphere or nanosphere, which consists basically of a spherical, nonporous, hard particle made up of long, entwined linear or crosslinked polymers. Creation of these particles typically involves an emulsion polymerization process that uses vinyl monomers, sometimes in the presence of... 

The emulsion liquid membrane for cephalosporins relies essentially on facilitated transport. There are basically, however, two types of facilitated transport in emulsion liquid membrane system, i. e.. Type I and Type II facilitation. In the first type, the concentration gradient of the membrane soluble solute/permeate... 

Early oxidation hair dyes were used in solution form these have been replaced by cream- or gel-based formulas. The oil-in-water emulsions commonly used can be supplemented with auxiliary ingredients, such as polymers to improve combing ability, as well as other conditioning additives. Extensive patent literature is available on this point [35], Gel formulations may be based on alcoholic solutions of nonionic surfactants or fatty acid alkanolamide solutions, which form a gel when mixed with the oxidant. The type (emulsion or gel) and the basic composition of the preparation strongly influence dyeing [47], Different base formulations with the same dye content yield varying color depths and shading due to the distribution of the dye between the different phases of the product, interaction with surfactants, and diffusion from the product into the hair. 

Part of the process to make cheese involves the flocculation of an electrostatically stabilized colloidal O/W emulsion of oil droplets coated with milk casein. The flocculation is caused by the addition of a salt, leading to the formation of networks which eventually gel. The other part of the process involves reaction with an enzyme (such as rennet), an acid (such as lactic acid), and possibly heat, pressure and microorganisms, to help with the ripening [811]. The final aggregates (curd) trap much of the fat and some of the water and lactose. The remaining liquid is the whey, much of which readily separates out from the curd. Adding heat to the curd (-38 °C) helps to further separate out the whey and convert the curd from a suspension to an elastic solid. There are about 20 different basic kinds of cheese, with nearly 1000 types and regional names. Potter provides some classification [811]. 

This book provides an introduction to the colloid and interface science of three of the most common types of colloidal dispersion emulsions, foams, and suspensions. The initial emphasis covers basic concepts important to the understanding of most kinds of colloidal dispersions, not just emulsions, foams, and suspensions, and is aimed at providing the necessary framework for understanding the applications. The treatment is integrated for each major physical property class the principles of colloid and interface science common to each dispersion type are presented first, followed as needed by separate treatments of features unique to emulsions, foams, or suspensions. The second half of the book provides examples of the applications of colloid science, again in the context of emulsions, foams, and suspensions, and includes attention to practical processes and problems in various industrial settings. 

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