(1) Emulsification: the oil has big surface tension in the water, so when water is dripped into the oil and stirred with efforts, the oil will be turned into fine beads and emulsion will appear due to the mixup but the layering will come out when the stirring stops. If surfactant is added and it is stirred forcibly, it is not easy for layering show up for a long time when the stirring is cut off, which is emulsification. The reason is that the hydrophobicity of oil is surrounded by hydrophilic group of active agent, leading to directional attraction so that the work needed for oil to disperse in the water is emusified by oil.
(2) Wetting: a wax, grease or scarly substances that are hydrophocibity will cover on the surfaces of components. Because of the pollution from these substances, it makes it difficult for the surfaces of components to be wet. When surfactant is put into aqueous solution is put into, the beads on the components find it easy to disperse, lowering the surface tension of them and achieving the goal of wetting.
(3) Solubilization: the grease can be "dissolved" only if surfactant is added. However, this kind of dissolution will occur only when the concentration of surfactant reaches the critical concentration of colloid. How the solubility is depends on the objects and properties for solubilization. As for solubilicity, its long hydrocarbon chain of hydrophobic gene is stronger than the short one and the saturated hydrocarbon chain is better than unsaturated one. The solubilization of non-ion surface active agent is rather significant.
(4) Dispersing: solid particles like dust and dirt will flock together easily, they will have settlement in the water without any difficulty. The molecules of surfactant can break the aggregate of solid particles into tiny ones, making it suspend and disperse in the solution, which plays a role in pushing solid particles to scatter evenly.
(5) Foaming effect: why bubbles form is because the oriented absorption of active agent and also is because the reduction of surface tension between gas and liquid. In general, the active agent with low molecule is easy to be foaming while the high one is not. Myristic acid yellow has the highest foaming property but sodium stearate has the worst. Anionic active agent has better foaminess and foam stability than non-ion type such as sodium alkylbenzene sulfonate. The foam stabilizer used commonly contains fat aliphatic alcohol and carboxymethyl cellulose and foaming inhibitor includes delspray, aliphatic ester, polyether and other non-ion surfactant.