In the petroleum industry, the emulsion of W/O or O/W both can cause huge financial losses if not treated properly. Among these classes only stable and mesostable are considered different from the two other states and they can be characterized as an emulsion.Īn oil-in-water emulsion is the emulsion in which the oil exists as the dispersed phase and water as the dispersion medium or continuous phase as shown in Figure 3. Eventually, it will remain about 10% in a period of one week. Finally, the entrained water is black in appearance and has 30 to 40% of water content for a few hours. Unstable emulsions are the emulsions that rapidly separate into two phases’ water and oil in a short time. Mesostable emulsions are founded brown or black and have properties are between stable and unstable emulsions such as O/W emulsions. Stable emulsions are brown in appearance and contain 60 to 80% of water. Fingas and Fieldhouse investigated that the mixture of W/O classified into four states: stable, mesostable, unstable, and entrained water. Several studies have shown that the stability is the most important characteristic in W/O emulsion and generally these emulsions stabilized with natural surfactants such as resin and asphaltenes Fridjonsson, et al. These compositions play a very important role in the formation of W/O emulsions. W/O emulsion and emulsifiers on the surface of the dispersed phase (Water). The three types of emulsion are displayed in Figure 1.įigure-2. The complex emulsion also known as a multiple emulsion. Types of EmulsionsĮssentially, there are three types of emulsions which are water-in-oil (W/O), oil-in-water (O/W), and complex emulsions such as water-in-oil-in-water (W/O/W). To understand more about the emulsions, this review is focused on the study of emulsions types, stability mechanisms and rheological studies. Therefore, addition of surfactants are necessary to make a stable emulsion for a period of long time. However, the emulsions formed without adding any surface active material would not be stable, and the emulsion phases will start to separate in different layers based on their density differences. To form an emulsion a mechanical force is required to disperse one phase into another. Although, some emulsions are stable as a result of the small drop sizes and the existence of interfacial film, which surrounds the drops. Inherently, an emulsion is an unstable system due to the unfavorable contact between oil and water phases. An emulsion is not contained only water and oil it may also contain some solid particles and even gas. Emulsions are found in different industries such as food, pharmaceutical, agricultural, cosmetics, and petroleum. Basically, an emulsion is consisting of a continuous phase which is known as external phase, where the droplets are dispersed, and a dispersed phase which is defined as internal or discontinuous phase. IntroductionĪn emulsion is a mixture of two immiscible liquid phases where one phase is dispersed into another. Keywords:Emulsion, Emulsion type, Stability mechanism, Viscosity, Droplet size. The purpose of this review article is to provide information about types of emulsions, stability mechanisms and rheological studies as well as factor affecting the stability of emulsions. To form stable emulsions, an emulsifier is required to reduce the droplet sizes of the emulsions and enhance the emulsion stability. The development and production of good quality emulsions depend on the knowledge of emulsion preparation, stability mechanisms and rheological studies. Sweeta Akbari 1* Abdurahman Hamid Nour 2ġ,2 Faculty of Chemical & Natural Resources Engineering, Universiti Malaysia Pahang, Lebuhraya Tun Razak, 26300 Gambang, Pahang, Malaysia.Įmulsions have been widely used in different industrial processes. Emulsion Types, Stability Mechanisms and Rheology: A Review
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