The key difference between suspending agent and emulsifying agent is that suspending agents are useful for the stabilization of suspensions, whereas emulsifying agents are useful in stabilizing emulsions.
Suspensions and emulsions are two different substance. An emulsion is usually a mixture of two liquids, while a suspension can be a mixture of two components from any phase (gas, liquid or solid). However, both are mixtures of two components.
CONTENTS
1. Overview and Key Difference
2. What is a Suspending Agent
3. What is an Emulsifying Agent
4. Side by Side Comparison – Suspending Agent vs Emulsifying Agent in Tabular Form
5. Summary
What is a Suspending Agent?
Suspending agents are chemical substances useful in stabilizing a suspension. These are also known as thickening agents. These are usually hydrophilic colloids that spontaneously form colloidal dispersions with water. This happens due to an affinity between the dispersed particles and the dispersion medium. These chemical agents are helpful in lowering the sedimentation rate of the particles in the suspension.
Generally, the sedimentation rate is slowed by suspending agents through increasing the viscosity of the liquid vehicle and by slowing down settling (according to the Stokes law). Moreover, suspending agents tend to prevent caking at the base of a suspension, and we can resuspend it by agitation.
Figure 01: Solution, Suspension, Supernatant, and Precipitate
There are three major types of suspending agents, including polysaccharides, inorganic salts and synthetic compounds. The most common polysaccharides we can use as suspending agents include natural polysaccharides such as acacia, starch, alginates, etc. Some examples of the inorganic salts that we can use as suspending agents include clay, bentonite, and aluminum hydroxide. Synthetic compounds are also made as suspending agents in order to overcome the various problems occurring from natural products. e.g. carbomers and colloidal silicon dioxide.
What is an Emulsifying Agent?
An emulsifying agent is a chemical substance that allows us to stabilize an emulsion. In other words, it can prevent the separation of liquids that usually do not mix with each other. Moreover, emulsifying agents do so by increasing the kinetic stability of the mixture. We can call them emulsifiers as well, and a good example is surfactants. There are two types of emulsifiers as lipophilic emulsifiers and hydrophilic emulsifiers.
Figure 02: Formation of an Emulsion
Lipophilic emulsifiers are emulsifying agents that work with oil-based emulsions. These chemical reagents are important in removing a penetrant when a defect due to over-washing of the emulsion is a concern. Lipophilic emulsifiers can make the excess penetrant more removable with washing using water. Usually, lipophilic emulsifiers are oil-based materialism, and these reagents are produced as ready-to-use agents by the manufacturer.
Hydrophilic emulsifiers are emulsifying agents that work with water-based emulsions. Similar to lipophilic emulsifiers, these chemical reagents also are important in removing a penetrant from a defect when over-washing of the emulsion is a concern. Here, lipophilic emulsifiers can make the excess penetrant more removable with washing using water. Usually, hydrophilic emulsifiers are water-based materials and are produced as a concentrate by the manufacturer. Therefore, we need to dilute the concentration of the hydrophilic emulsifier using water to a preferable concentration before using it.
What is the Difference Between Suspending Agent and Emulsifying Agent?
Suspensions and emulsions are two different mixtures. Therefore, suspending agents and emulsifying agents are also different from each other. The key difference between suspending agent and emulsifying agent is that suspending agents are useful for the stabilization of suspensions, whereas emulsifying agents are useful in stabilizing emulsions.
Below is a summary of the difference between suspending agent and emulsifying agent in tabular form.
Summary – Suspending Agent vs Emulsifying Agent
Both suspensions and emulsions are mixtures of two components, but emulsions are essentially made of two liquids, while suspension can be made from material in any phase. Therefore, the stabilizing agents that we should use for them are also different. The key difference between suspending agent and emulsifying agent is that suspending agents are useful for the stabilization of suspensions, whereas emulsifying agents are useful in stabilizing emulsions.
Reference:
1. Singh, Silvi. “Suspending Agents.” SlideShare, 19 May 2016, Available here.
Image Courtesy:
1. “Chemical precipitation diagram” By Vectorized by ZooFari; raster by ZabMilenko – Own work based on Chemical precipitation diagram.png (Public Domain) via Commons Wikimedia
2. “Chemical precipitation diagram” By Fvasconcellos 14:24, 17 April 2007 (UTC) – Own work, after Image:Emulsions.png by Ike9898, Public Domain) via Commons Wikimedia