Anionic Surfactants vs Nonionic Surfactants

Difference Between Anionic Surfactants and Nonionic Surfactants

The key difference between anionic cationic and nonionic surfactants is that anionic surfactants contain negatively charged functional groups, and cationic surfactants contain positively charged functional groups, whereas nonionic surfactants have no net electrical charge.

The term surfactant refers to surface-active agents. That means, the surfactants can reduce the surface tension between two substances. For example, two substances can be two liquids, a gas and a liquid or a liquid and a solid. There are three main types of surfactants as anionic, cationic and nonionic surfactants. These three types differ from each other according to the electrical charge of the compound.

What are Anionic Surfactants?

Anionic surfactants are a type of surface-active agents that contain negatively charged functional groups in the head of the molecule. Such functional groups include sulfonate, phosphate, sulfate and carboxylates. These are the most common surfactants we use. For example, soap contains alkyl carboxylates.

What are Nonionic Surfactants?

Nonionic surfactants are a type of surface-active agents that have no net electrical charge in their formulations. That means, the molecule does not undergo any ionization when we dissolve it in water. Furthermore, they have covalently bonded oxygen-containing hydrophilic groups. These hydrophilic groups bind with hydrophobic parent structures when the surfactant is added to a sample. The oxygen atoms in these compounds can cause the hydrogen bonding of the surfactant molecules.

Since the hydrogen bonding is affected by temperature, temperature increasing decreases the dissolution of these surfactants. Furthermore, there are two major forms of nonionic surfactants according to the differences in their hydrophilic groups as follows:

• Polyoxyethylene
• Polyhydric Alcohols