Adsorbent vs Absorbent: Difference and Comparison

Both of the terms refer to a ‘process.’ Although the names sound similar and might look alike at first glance, the difference is extravagant. 

To decipher layman’s language, we can cite the adsorbent as getting smacked by a cake on the face, whereas absorbent as eating the cake.  

Key Takeaways

1. Adsorbents attract and hold molecules on their surface, while absorbents incorporate molecules into their structure.
2. Common adsorbents include activated carbon and silica gel, while examples of absorbents are sponges and paper towels.
3. Adsorbents are primarily used in gas and liquid purification processes, while absorbents are used for cleaning spills and retaining moisture.

Adsorbent vs Absorbent

Adsorbents are used in a variety of applications, such as water treatment, gas masks, and chromatography. Absorbents are materials that absorb liquid or gas, such as sponges, paper towels, and diapers. They are used in a variety of applications, such as cleaning up spills, personal hygiene products.

The deposition of molecular species onto a surface is known as an adsorbent. The adsorbent is the molecular species that gets adsorbed on the surface, and the adsorbate is the surface on which adsorption takes place.

Separation of inert gases, heterogeneous catalysis, removal of coloring matter from solution, and desiccation, etc., are a few examples of adsorbents.

Absorption is the way of chemicals are absorbed or entered, or taken into a solid or liquid body from the outside. The process involves bulk incorporation of turning a component into a solid material.

The cellulose sponge is an example. When the sponge comes into contact with water, it absorbs it and swells. 

Comparison Table

Parameters for comparison	Adsorbent	Absorbent
Definition	The adsorbent is the contact of solids with either liquids or gases in which the mass transfer is towards the solid.	A phenomenon or process that involves molecules, atoms, or atoms undergoing bulk phase for absorption is known as absorbent.
Nature	It is endothermic.	It is exothermic.
Types	Physical adsorption and chemisorption.	There are various types of absorbents. Hazmat and reusable absorbent are one of them.
Effect of temperature	The amount of solute adsorbed from a mixture reduces as the temperature rises at a constant pressure.	Results in a decrease in temperature in aqueous glucose with an increase in temperature.
Uses	Decolorizing and drying of lubricating oils, kerosene, and engine oils.	Used in bandages, towels, bath mats, paper towels,

What is Adsorbent?

We infer the system of liquid or gas molecules clasping the solid particles to the surface as adsorption. 

Substances are absorbed onto an adsorbent’s skin because the adsorbent contains unoccupied spaces that encourage particle attachment to the gaps.

In adsorption, the surface’s energy drops, decreasing the surface’s residual forces. The rate of adsorption continuously increases until they reach equilibrium. 

A variety of living and non-living systems use adsorption.

Adsorption is a mechanism that living systems like viruses use to attach to bacteria or other organisms. Adsorption chromatography, for example, uses the principle of adsorption to separate mixtures.

Ample adsorbent must have a wide surface area to allow significant amounts of other phases, such as gases and vapors, to accumulate. 

Application of adsorbent:

1. In the gulp of the mines, miners use this capability to eliminate dangerous chemicals from the air they breathe.

2. The adsorbent can filter water by eliminating harmful or carcinogenic colors, heavy metal cations, and organic contaminants.

3. They are used as catalyst carriers in the industry for a range of chemical processes that are helpful in the industry.

What is Absorbent?

The term ‘absorbent’ is used in chemistry to describe a method of collecting and assimilation chemicals into a surface, such as a cell, or across tissues via diffusion or osmosis.

The absorbent’s overall energy increases after absorption due to endothermic.

Absorption has a constant rate throughout.

The absorption phenomenon is used by inhabiting systems such as unicellular organisms to take in nutrients and water. 

Refrigerators, for example, use absorption to keep their contents cold. It equally disperses the molecule throughout the body/medium during absorption.

Absorption is a mass transfer operation in which the liquid moves steadily upwards in volume while the gas moves downwards. 

When the temperature rises, gas molecules quickly migrate upwards, resulting in an extremely short contact duration between the liquid and gas phases.

How does absorption happen?

We can explain this with a sponge case.

Liquids can be absorbed in two ways: 

Physically and physicochemically. 

The first arises because of H-bonding between substance and water molecules with water. However, water is trapped in the material’s vacuum areas in the second.

Because sponges have porous and cellular structures, abundant water can get trapped inside those empty areas.

Main Differences Between Adsorbent and Absorbent

1. Adsorbed solutions are chemically weakly bound and require energy input to break the bonds. In contrast, absorbed solutions require physical infiltration to limit the amount of solution.

2. Adsorption is an exothermic process with a stable reaction rate that achieves equilibrium. Absorption is an endothermic process with a uniform reaction rate.

3. The concentration of the adsorbed substance changes from the bulk to the bottom of the adsorbent in adsorption; however, the concentration of the absorbed substance does not change throughout the medium of absorption.

4. Adsorption is more effective at lower temperatures. Absorption is unaffected by temperature.

5. Air conditioning and water purification are examples of adsorption applications. Whereas cold storage, ice manufacturing, turbines, and refrigerants are examples of absorption applications.

References

1. https://pubs.acs.org/doi/abs/10.1021/acs.iecr.5b03649
2. https://iwaponline.com/wst/article-abstract/26/5-6/1205/26956
3. https://psycnet.apa.org/getdoi.cfm?doi=10.1037/0022-3514.59.1.91
4. https://api.taylorfrancis.com/content/books/mono/download?identifierName=doi&identifierValue=10.1201/b12439&type=googlepdf