Adsorption and absorption are two distinct processes that involve the interaction of substances with a solid or liquid surface. Here are the key differences between adsorption and absorption:

1. Nature of Interaction:

• Adsorption: Adsorption refers to the adherence or accumulation of atoms, ions, or molecules from a gas or liquid phase onto the surface of a solid or liquid. It involves weak intermolecular forces of attraction between the adsorbate and the adsorbent. The adsorbate remains on the surface without penetrating or entering the interior of the adsorbent material.
• Absorption: Absorption involves the penetration or uptake of a substance (liquid or gas) into the bulk of a solid or liquid material. The absorbed substance disperses within the absorbing material, entering its interior or matrix. Absorption can involve dissolution of the absorbed substance in the absorbing material.

2. Surface Area:

• Adsorption: Adsorption occurs specifically at the surface of the adsorbent material, taking place only on the exposed surface area. The concentration of the adsorbate is generally higher at the surface compared to the bulk.
• Absorption: Absorption occurs throughout the bulk of the absorbing material, not limited to the surface area. The absorbed substance permeates or disperses within the absorbing material.

3. Reversibility:

• Adsorption: Adsorption is typically a reversible process, meaning that the adsorbate can be desorbed or removed from the surface under suitable conditions, such as changes in temperature or pressure.
• Absorption: Absorption is not necessarily a reversible process. The absorbed substance may remain within the bulk of the absorbing material and might not be easily released.

4. Energy Involved:

• Adsorption: Adsorption generally involves weak intermolecular forces (such as van der Waals forces) between the adsorbate and the adsorbent. The energy associated with adsorption is lower than that of chemical bonds.
• Absorption: Absorption often involves stronger interactions, such as chemical bonds or intermolecular forces, between the absorbed substance and the absorbing material. The energy associated with absorption is generally higher than that of adsorption.

In summary, adsorption refers to the adherence of substances onto a surface, occurring at the surface and involving weak intermolecular forces. Absorption, on the other hand, involves the penetration of substances into the bulk of a material, occurring throughout the material and often involving stronger interactions.