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Biosurfactant as an Antimicrobial and Biodegradable Agent a Review
Published in R.Z. Sayyed, Microbial Surfactants, 2022
The efficiency of biosurfactants as emulsifiers is well known and widely used in the emulsification process. The applications of biosurfactants in different industries particularly in pharmaceutical and cosmetic formulations were found to have a satisfactory result due to their low toxicity and higher biodegradability. Generally, biosurfactants with higher molecular mass are considered effective emulsifiers to stabilize the emulsions for a long period of time (Nitschke and Costa 2007). In terms of preparing nano-emulsions, higher homogenizing speed would be effective to disperse the phase in nano-sizes (Bhadoriya et al. 2013). There are two types of emulsions: oil-in-water (O/W) and water-in-oil (W/O). In an O/W type, the continuous phase is water referring to as water-based emulsions. However, the oil-based emulsion is a W/O type, whereby the oil acts as the continuous phase. The main function of an emulsifier surfactant is to accumulate between phases and lower the surface and interfacial tensions of the emulsion which finally results in the formation of an emulsion. Moreover, the cosmetic and pharmaceutical formulations deal with both emulsion types (Masmoudi et al. 2005). In cosmetics, plant-based essential oils are considered as an important component for moisturizing and anti-aging purposes (Ferreira et al. 2017). In order to stabilize these types of emulsions, the presence of surfactants as emulsifiers is necessary. Particularly, bio-based surfactants are safe as they can cure in a natural way (Vijayakuma and Saravanan 2015).
Corrosion
Published in Mavis Sika Okyere, Mitigation of Gas Pipeline Integrity Problems, 2020
An emulsion is a mixture of two or more normally immiscible liquids like oil and water. In typical water in oil emulsion, tiny bubbles of water are interspersed within the oil and are stabilized by surface forces. An emulsion breaker destabilizes the bubbles releasing the liquid, which is then forced to form large bubbles, using electrostatics, and settle out by gravity.
The role of emulsifiers in the kinetics and mechanisms of emulsion polymerization
Published in David R. Karsa, Surfactants in Polymers, Coatings, Inks and Adhesives, 2020
The term ‘emulsifier’ makes its purpose clear, that is, to help the dispersion of immiscible liquids and to stabilize the resulting emulsion. The generic term is surfactant, which is derived from surface-active agent, and means that this kind of substance is concentrated/adsorbed at interfaces (AI denotes the total interfacial area) instead of being dissolved in the volume. The driving force for this adsorption process is the lowering of the interfacial free energy, ΔGI, due to decreasing the interfacial tension, γ: ()ΔGI=γAI
Effect of ultrasonic homogenization on crude oil-water emulsion stability
Published in Journal of Environmental Science and Health, Part A, 2023
Nahid Hassanshahi, Guangji Hu, Kenneth Lee, Jianbing Li
Increasing crude oil production, transportation, and storage activities would lead to increased environmental risk due to oil spills and leaks on land and sea. [1] As crude oil is a complex mixture containing toxic compounds like monocyclic and polycyclic aromatic hydrocarbons, known as carcinogenic, teratogenic, and mutagenic toxic substances, [2] accidental spills can pose severe health risks to a range of biota, including humans. [3] Following its accidental release into the environment, oil emulsions may be naturally generated by mixing components to create two phases: a dispersed phase and a continuous phase (i.e., bulk phase). Oil-in-water (O/W) and water-in-oil (W/O) are the common types of emulsion. [4,5]
Preparation of monodisperse water-in-oil emulsions using microchannel homogenization
Published in Particulate Science and Technology, 2022
Ran Li, Isao Kobayashi, Yanru Zhang, Marcos A. Neves, Kunihiko Uemura, Mitsutoshi Nakajima
An emulsion is a dispersion of two or more immiscible liquids, with one liquid dispersed in the other as droplets or particles. The major types of emulsions include single emulsions [e.g., oil-in-water (O/W) and water-in-oil (W/O)] and double emulsions [e.g., water-in-oil-in-water (W/O/W) and oil-in-water-in-oil (O/W/O)] (Kobayashi et al. 2012; McClements 2015). W/O emulsions, which are generally stabilized using hydrophobic surfactants, are widely used in the formulation of foods, pharmaceuticals, biomedical cosmetics, and chemicals. The droplet size and uniformity of W/O emulsions are critical determinants of important properties, such as stability against coalescence, aggregation, sedimentation, rheology, chemical reactivity, and physiological efficiency of encapsulated components, in the abovementioned applications (McClements 2015). Mechanical emulsification devices, such as colloid mills, high-pressure homogenizers, rotor-stator homogenizers, and ultrasonic homogenizers, have traditionally been used to produce W/O emulsions. However, such W/O emulsions are usually polydisperse, and their droplet size and distribution are poorly controlled (coefficient of variation (CV) typically >20%). The majority of the energy input during mechanical emulsification dissipates as heat (e.g., >99% for high-pressure homogenizers) (Gijsbertsen-Abrahamse, van der Padt, and Boom 2004). These factors may reduce the quality of W/O emulsion-based products.
Ionic liquids as demulsifies for crude oil. Synthesis, characterization, and evaluation
Published in Petroleum Science and Technology, 2022
Erik J. Del Ángel-Gómez, Nohra V. Gallardo-Rivas, Ulises Paramo-García, Nancy P. Díaz-Zavala, Ernestina E. Banda-Cruz, Reinaldo D. Martínez-Orozco, Ricardo García-Alamilla
There are two basic types of emulsions: oil-in water (O/W) and water-in oil (W/O). The difference in both emulsions is the dispersed phase: oil in the first case and water in the second case (Martinez-Palou et al. 2015; Ezzat et al. 2018; Hazrati, Beigi, and Abdouss 2018; Adewunmi and Kamal 2019; Hassanshahi, Hu, and Li 2020; Yonguep and Chowdhury 2021). The results of cyclic voltammetry, as a function of the water content for W/O emulsion in the presence of the ionic liquids (800 ppm) show that [HMIm][ToS] exhibits higher ionic conductivity up to 50% volume water concentration (Figure 3c). This is attributed to a better interaction between [HMIm][ToS] with crude oil and water, derived from the amphipathic character of its constituent anion. This same tendency is observed to less water concentrations in the emulsion, as can be observed in the Figure 3a,b. The lack of redox peak suggested that the electrochemical response only reveals the ionic charge transfer from the aqueous phase to the electrical double-layer. This result shows the significant effect of water content on the conductivity of ionic liquids (Aranowski et al. 2016; Lara-Hernández et al. 2021; Villalobos-Neri et al. 2021). As the water content in the W/O emulsion increases, a lower resistance of the media is observed, so the ionic conductivity increased. This increase in conductivity is associated with the presence of ionic and polar compounds in the emulsions.