ABSTRACT
Surfactants (short for surface-active agents) are organic amphiphilic substances, which means they contain both hydrophobic and hydrophilic groups in their structures. The hydrophobic group (tail) is often a linear alkyl chain with 8-20 carbon atoms attached to the hydrophilic group (head), which is either electrically charged, negatively or positively, or a neutral polar group. Depending on the charge of the hydrophilic group, surfactants are classied into four groups: anionic, cationic, zwitterionic, and nonionic. Therefore, a surfactant molecule contains both a water-insoluble part and a water-soluble part, which makes it ideal to be used as an active ingredient in detergents. However, surfactants are also used as emulsiers, wetting agents, foaming agents, and dispersants (Uzoukwu and Nollet 2000, Waldhoff and Spilker 2005).
