The key difference between dispersant and surfactant is that the dispersant improves the separation of particles in a suspension whereas the surfactant is a substance that can lower the surface tension between two phases of matter.
A dispersant is a form of surfactant. But all surfactants are not dispersants. A surfactant can act as a detergent, wetting agent, emulsifier, foaming agent apart from acting as a dispersant. Usually, both of these are organic compounds.
CONTENTS
1. Overview and Key Difference
2. What is Dispersant
3. What is Surfactant
4. Side by Side Comparison – Dispersant vs Surfactant in Tabular Form
5. Summary
What is Dispersant?
A dispersant is a liquid or gas used to disperse small particles in a medium. We call it “plasticizers” as well. There are two forms of them; non-surface active polymers and surface active substances. We add these substances into a suspension in order to avoid the formation of clusters of particles. This improves the separation of particles in order to avoid the cluster formation. Moreover, this process prevents the particles from settling. Most of the times, a dispersant is consist of one or more surfactant substances.
Figure 01: The Mechanism of Action of a Dispersant
The applications of these substances include the production of automotive engine oils, prevention of the formation of biofilms in various industries, in concrete mixing to avoid the use of a large amount of water, in oil drilling to break up solids into particles.
What is Surfactant?
A surfactant is a substance that can lower the surface tension between two phases of matter. It can lower the surface tension between two liquids, between a gas and a liquid or between a liquid and a solid. Most of the times, these are amphiphilic organic compounds. This means these substances contain both hydrophilic and hydrophobic regions in the same molecule. Therefore, they contain both water soluble and water insoluble regions.
Figure 02: Hydrophilic and Hydrophobic Regions of Surfactant Molecules
The applications of surfactants include its role as a cleaning agent, wetting agent, dispersant, emulsifier, foaming and anti-foaming actions in many products such as detergents, emulsions, paints, soaps, inks, anti-fogs, adhesives, insecticides, etc.
What is the Difference Between Dispersant and Surfactant?
A dispersant is a liquid or gas used to disperse small particles in a medium. A surfactant is a substance that can lower the surface tension between two phases of matter. However, a dispersant is a form of surfactant. These two substances differ from each other according to their functionality. This means a dispersant prevents the formation of clusters of particles in a suspension while a surfactant lowers the surface tension between two liquids, between a gas and a liquid or between a liquid and a solid. This is the key difference between dispersant and surfactant. Moreover, a dispersant does its job via adsorbing orienting the particles on the liquid-air interface whereas a surfactant does its job via adsorbing on to the solid-liquid interface; thus assures the repulsion between particles.
The below infographic presents more details on the difference between dispersant and surfactant in tabular form.
Summary – Dispersant vs Surfactant
A dispersant is a form of surfactant. The difference between dispersant and surfactant is that a dispersant improves the separation of particles in a suspension whereas a surfactant is a substance that can lower the surface tension between two phases of matter.
Reference:
1. “Dispersant.” Wikipedia, Wikimedia Foundation, 14 Aug. 2018. Available here
2. “Surfactant.” Wikipedia, Wikimedia Foundation, 22 Aug. 2018. Available here
Image Courtesy:
1.”Dispersant Mechanism” By Dahlia88 – Own work, (CC BY-SA 3.0) via Commons Wikimedia
2.”Micelle scheme-en”By SuperManu – Own work, (CC BY-SA 3.0) via Commons Wikimedia