How do surfactants stabilize emulsions?
They reduce the oil-water interfacial tension; thereby minimizes the energy required for emulsion formation. The adsorbed surfactant molecules at the interface act as electrostatic or steric barriers against droplet coalescence and increase the emulsion stability.
What is used to stabilize emulsion?
Monolayer Stabilization. The traditional approach to emulsion stabilization is to consider either the oil droplets or water droplets to be covered by a homogenous layer of a surfactant giving rise to stable oil-in-water or water-in-oil emulsions. Both ionic and nonionic surfactants are used for this purpose.
What is surfactant in emulsion?
Surfactant is the broadest term: Both emulsifiers and detergents are surfactants. Surfactants, or surface-active agents, are compounds that lower the surface tension between two liquids or between a liquid and a solid.
Which emulsifier is used to stabilize the emulsion of water in oil?
Although polyglycerol polyricinoleate (PGPR, E476) is considered as the ‘classic’ surfactant when it comes to stabilization of W/O emulsions, the focal point of current research has recently shifted towards the use of particle stabilizers that allow longer term stabilization against coalescence and Ostwald ripening.
What does the surfactant Stabilise?
The main purpose of the surfactants is to decrease the surface and interfacial tension and stabilize the interface.
What does it mean to stabilize an emulsion?
From a thermodynamic point of view, an emulsion is an unstable system, since there is a natural tendency for a liquid-liquid system to separate and reduce its interfacial energy. Emulsion stability can be defined as the system’s ability to resist changes in its physicochemical properties over time.
How do you stabilize water in oil emulsion?
Compounds with higher solubility in the oil phase than in the aqueous phase are the most likely emulsifying agents to produce stable water-in-oil emulsions. Waxes and sea water particles, such as clays, can contribute to the stability of water-in-oil emulsions, but cannot by themselves produce stable emulsions.
How does surfactant impart stability?
surfactant adsorbs at the interface between the oil membrane phase and internal phase at higher surfactant concentration, thus enhances the strength of adsorption layer and increase stability.
How are surfactant used as emulsifying agent?
Surfactants are useful because they allow oil and water to mix, creating emulsions. The emulsifier positions itself at the oil/water or air/water interface and, by reducing the surface tension, has a stabilising effect on the emulsion.
How are emulsions Stabilised?
As mentioned, emulsions are stabilized with surfactants (emulsifying agents) that have affinities for both phases; these decrease the energy required to make new surfaces between the two phases, the interfacial surface tension. Destabilization of an emulsion is an example of coagulation (or coalescence) of colloids.
Why stability of emulsion is important?
The stability of emulsions is very important during storage. To administer the emulsion in the body, it is necessary to have good stability. Instability of emulsions leads to floating of droplets to the surface, cohesion between droplets, and finally to creaming and separation.
How do you know if an emulsion is stable?
The turbidity measurement is a simple and inexpensive method of determining the stability of an emulsion. It represents an indirect method for evaluation of emulsion stability by correlating the particle size distribution and the turbidity of colloidal systems.
Does the molecular structure of surfactant affect emulsion stability?
Therefore, the investigation of effects of the molecular structure of surfactant on emulsion stability, especially from the perspective of molecular structure affecting the interfacial film properties, is beneficial to design and select surfactant properly and reasonably.
What is the best surfactant for emulsification?
The ideal surfactant requires short interfacial adsorption duration, strong ability to reducing interfacial tension, and high coverage over water-oil interfacial after adsorption [ 8, 9 ]. The rapid adsorption of surfactant helps the interfacial tension reach a lower equilibrium value speedily to promote the droplets formation during emulsifying.
Can oil-in-water nanoemulsion be stabilized by polymeric surfactant?
Kumar N., Mandal A. Oil-in-water nanoemulsion stabilized by polymeric surfactant: Characterization and properties evaluation for enhanced oil recovery. Eur. Polym. J. 2018; 109 :265–276. doi: 10.1016/j.eurpolymj.2018.09.058.
What affects the viscoelastic modulus of interfacial surfactants?
The interfacial viscoelastic modulus was reported mainly affected by the density of surfactant molecules at the interface [ 9, 38 ]. When the interface expanded, the density of surfactant molecules at the interface decreased, improving the interface tension.