The oriented wedge theory of emulsions and the inversion. Both the phase behavior and emulsion stability are argued to be dependent on the bending elasticity of the surfactant monolayer at the oil. The oriented wedge theory of emulsions and the inversion of emulsions. The preparation of emulsions requires energy to disperse the organic phase solvent or solution in water. Common examples of emulsions include egg yolk, butter, and mayonnaise. The oriented wedge theory of emulsions pdf free download. Double emulsions may be either of the waterinoilinwater type wow with dispersed oil globules containing smaller aqueous droplets or of the oilinwaterin oil type owo with dispersed aqueous globules containing smaller oily dispersed droplets. The oriented wedge theory of emulsions indicates thatif thenonpolarendofthemoleculeof theemulsifying agent is the smaller, the emulsion will be one of oil in wateror of the ordinary typewhile if the polar endis the smaller, the droplets will be of water. Orientedwedgetheory concept this theory deals with formation of monomolecular layers of emulsifying agent curved around a droplet of the.
That different stabilizers led to preferential curvature of the oilwater interface was first suggested under the title of the oriented wedge theory5. Emulsification is not a spontaneous process and hence emulsions have minimal stability. The oriented wedge theory of emulsions and the inversion of emulsions1 for the formation of an emulsion the presence of an emulsifying agent is essential, except in the case in which the emulsion is very dilute. Ppt emulsions powerpoint presentation free to download. Pdf preparation of stable direct emulsions stabilized with. Ipp240b heterogeneous dispersions emulsions microemulsion 2 emulsion an emulsion is a dispersion in which the dispersed phase is composed of small. A simple geometric theory for the stabilization of. This based on the presumption that certain emulsifying agents orient themselves about and within a liquid in a manner reflective of their solubility in that particular liquid. Harkins proposed an oriented wedge theory of emulsions. A simple geometric theory for the stabilization of emulsions is that of the oriented wedge, in which the adsorbed surfactant molecules are assumed to form a uniform structure of wedges around the emulsion droplet. According t o this theory the oillike or non polar ends of. Preparation of stable direct emulsions stabilized with a system of phospholipid emulsifiers. This theory deals with formation of monomolecular layers of emulsifying agent curved around a droplet of the internal phase of the emulsion.
Disrupt the oriented structure of the emulsifiers interfacial phase with. This theory requires that to achieve maximum interfacial density of emulsifier, thus producing the maximum decrease in free energy and the maximum increase in strength of interfacial film the end of a surfactant emulsifier molecule, which has the greater crosssectional area, should be oriented toward the. Emulsions free download as powerpoint presentation. It possess internal forces that tend to promote association of the molecules to resist distortion of the sphere. Diy brick rocket stove cooking without electrical power duration. The group with the larger cross sectional area will be oriented outside of the droplet. At positive spontaneous curvatures, ow emulsions are stable. Theory oriented wedge theory interfacial film theory. Scribd is the worlds largest social reading and publishing site. All liquids have tendency to assume a shape having the minimal surface area exposed.
Thetheory of molecular orientation in surfaces is thus of primeimpor. The strategy was put forth in a discovery institute manifesto known as the wedge document. Annotations are viewable on desktop computers or desktop site of mobile devices. Emulsifying agent anti oxidants antimicrobial preservative. Of the typical soluble emulsifying agents sodium oleate may be cited as an example.
The oriented wedge theory revisited american chemical society. Doc types of emulsifying agents rehan ashraf academia. The liquid droplets the disperse phase are dispersed in a liquid medium the continuous phase. This theory requires that to achieve maximum interfacial. The stability of emulsions, monomolecular and polymolecular films, thickness of the water film on salt solutions, and the spreading of liquids. Emulsion is a type of liquid dosage form for pharmaceutical use. Full text full text is available as a scanned copy of the original print version. The wedge strategy was designed with both fiveyear and twentyyear goals in mind in order to achieve the conversion of the mainstream. This theory for the manner in which emulsions are stabilized has been developed from the work of langmuir and of harkins. In a system containing two immicible liquids, emulsifying agents would be preferentially soluble in one. The oriented wedge theory of emulsions created date. The oriented wedge theory of emulsions and the inversion of. Aug 20, 2018 theories of emulsions monomolecular adsorption theory oriented wedge theory oriented adsorption theory plastic or interfacial. It is based upon the concept that the molecules of the emulsifier orient themselves in the interface between the dispersed and continuous phases, forming a wedge, the curvature of which determines the.
An emulsion is usually a mixture of two products such as oil and water that do not mix together or. Get a printable copy pdf file of the complete article 696k, or click on a page image below to browse page by page. Oriented wedge theory this theory assumes monomolecular layers of emulsifying agent curved around a droplet of the internal phase of the emulsion depending on the solubility of these agents in that particular liquid. An emulsion is a type of colloid formed by combining two liquids that normally dont mix. In an emulsion, one liquid contains a dispersion of the other liquid. Articles from proceedings of the national academy of sciences of the united states of america are provided here courtesy of national academy of sciences. Phase can be easily flavored to isolate the unpleasant taste of the dispersed phase from the tongue. What is harkins oriented wedge theory according to the oriented wedge theory, the difference in the relative size of the polar and nonpolar groups of the surfactant explains the type of the formed emulsion. Preparation of stable direct emulsions stabilized with a.
One notable component of the work was its desire to address perceived social consequences and to promote a social conservative agenda on a wide range of issues including abortion, euthanasia, sexuality, and. The correspondence between the equilibrium phase behavior of oilwater. The wedge strategy is a creationist political and social action plan authored by the discovery institute, the hub of the pseudoscientific intelligent design movement. Wo emulsions are generally formed if the aqueous phase constitutes oriented wedge theory of emulsions and the inversion of emulsions. This assumes mono molecular layers of emulsifying agent curved around a droplet of the internal phase of the emulsion.
Pharmaceutical applications of emulsions widened especially after micro and nanoemulsion emergence. Because emulsifying agents have hydrophilic portion and hydrophobic portion, they orient themselves according to solubility. To disguise the taste or oiliness of medicinal oils such as liquid paraffin and cod liver oil. Theories of emulsions monomolecular adsorption theory oriented wedge theory oriented adsorption theory plastic or interfacial. Emulsion formation, stability, and rheology tharwat f. Live simple, live free tinyhouse prepper recommended for you. This paper is an attempt to summarise comparative aspects like definition, theories, types, methods of preparations, advantages, disadvantages and methods of analysis of emulsion. Reasons for instability can be understood from the nature of immiscible. This paper is an attempt to summarise comparative aspects like definition, theories, types, methods of preparations, advantages, disadvantages and methods of analysis of emulsion, microemulsion and nanoemulsion.
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