Difference Between Anionic Cationic 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.

CONTENTS

1. Overview and Key Difference
2. What are Anionic Surfactants 
3. What are Cationic Surfactants 
4. What are Nonionic Surfactants 
5. Side by Side Comparison – Anionic Cationic vs Nonionic Surfactants in Tabular Form
6. Summary

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 Cationic Surfactants?

Cationic surfactants are a type of surface-active agents that contain positively charged functional groups in the head of the molecule. Most of these surfactants are useful as antimicrobials, antifungal agents, etc. It is because they can disrupt the cell membranes of bacteria and viruses. The most common functional group we can find in these molecules is ammonium ion.

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

What is the Difference Between Anionic Cationic and Nonionic Surfactants?

There are three main types of surfactants as anionic, cationic 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. Examples for anionic surfactants include the chemical compounds containing sulfonate, phosphate, sulfate and carboxylates. The cationic surfactants mainly contain ammonium cation. There are two major types of nonionic surfactants as polyoxyethylene and polyhydric alcohols.

The following infographic summarizes the difference between anionic cationic and nonionic surfactants.

Summary – Anionic Cationic vs Nonionic Surfactants

The term surfactant is used to name surface-active agents. There are three main types of surfactants as anionic, cationic 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.

Reference:

1. Helmenstine, Anne Marie. “What Is a Surfactant?” ThoughtCo, Feb. 11, 2020, Available here.
2. Helmenstine, Anne Marie. “Understanding How Detergents and Surfactants Work and Clean.” ThoughtCo, Feb. 11, 2020, Available here.
3. Williams, Jesse J. “Formulation of Carpet Cleaners.” Handbook for Cleaning/Decontamination of Surfaces, 2007, pp. 103–123., doi:10.1016/b978-044451664-0/50004-8.

Image Courtesy:

1. “Surfactant” By Major measure – Own work (Public Domain) via Commons Wikimedia
2. “Diagram of Surfactant 2” By BQUB19-PDonatiu – Own work (CC BY-SA 4.0) via Commons Wikimedia