Surfactants: Basic Overview

Surfactants are the abbreviation of ‘SURFace ACTive agenTS’.

Surfactants reduce surface/interfacial tension between two phases. They have tendency to gather around the interface between two different materials by altering the properties of interface remarkably. They also reduce the interfacial tension between oil and water by adsorbing at the liquid-liquid interface. They reduce the surface tension of water by adsorbing at the liquid-gas interface. So, Surfactants serves as good mediator to settle clash between two phases which are not friends (soluble). 

Surfactants play an important role as cleaning, wetting, dispersing, emulsifying, foaming and anti-foaming agents in many practical applications and products. 

Surfactants take part in producing Soaps, Detergents, Cosmetics: Shampoos, Hair conditioners (after shampoo), Toothpastes, Fabric softeners, Emulsions, Paints, Adhesives, Inks, Deinking of recycled papers, in flotation, washing and enzymatic processes, Agrochemical formulations, Alkali Surfactant Polymers (used to mobilize oil in oil wells).

Examples:

1. The most familiar use of surfactants is in making soaps, laundry detergents, dish-washing liquids, shampoos, hair conditioners (after shampoo) and toothpastes.
2. Among the numerous uses in pharmaceuticals, surfactants used for solubilization of hydrophobic drugs in aqueous media, as components of emulsion.
3. In surfactant-based enhanced oil recovery, the oil reservoir is flooded by pumping in water containing a small percentage of surfactant(s). The surfactant(s) overcome natural capillary forces by lowering the crude oil/water interfacial tension (IFT) to an ultra-low level which allows oil globules (ganglia) in the reservoir to flow through rock pores and coalesce to form a clean oil bank. Water flooding can aid in oil recovery from 1% to between 20-40%. After water flooding, the remaining oil could either be residual oil from the area swept by water or by-passed oil which could not be swept by the flooding. A surfactant model is an Enhanced Oil Recovery (EOR) mechanism aimed at reducing the residual (remaining) oil at the water-swept zones of the reservoir.
4. Ink is a colloidal system of fine pigment particles dispersed in a solvent. During the ink manufacturing dispersants are used to obtaining a stable dispersion and to prevent the fine pigment particles from reaggregating during the grinding stage. Wetting used to control surface properties. Defoamer/ antifoaming agents used to regulate foam efficiency. Whereas in flotation de-inking dispersants separates the ink particles from the fiber surface and prevent the redeposition of separated particles on fibers; Surfactants acts as a collector to agglomerate small ink particles to large ones and change the surface of particles from hydrophilic to hydrophobic; Also they acts as a frother (froth= foam at Solid/liquid surface) to generate a foam layer at the top of a flotation cell for ink removal.
5. Other important uses are in many industrial applications for surfactants in lubricants, emulsion polymerisation, textile processing, mining flocculates, petroleum recovery, wastewater treatment and many other products and processes. Surfactants are also used as dispersants after oil spills.

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 Manu and Ram