9 Difference between Absorption and Adsorption (With Table)

Chemistry is a branch of science that deals with the study of matter with its properties. It also describes how two substances combine with another substance with unique chemical properties. 

Besides that, it provides further descriptions on how to separate substances to give rise to a third substance. But all these chemical activities are possible due to intermolecular forces. 

Intermolecular forces are responsible for attraction attributes between the same and different atoms or ions or molecules. The formation of a new substance occurs due to the attraction or repulsion of these atoms or molecules. 

Examples of intermolecular forces are ion bonding, hydrogen bonding, and Van Der Waals Forces. These forces result in physical differences between similar molecules in terms of boiling and melting points. 

So, what is the main difference between absorption and adsorption? The former is the distribution of certain substances throughout the volume of another substrate while the latter is the attachment of a certain substance onto the surface of another substrate.

This article provides an explanation of the mechanism of adsorption and further differences between absorption and adsorption in a tabular form. Take time to read through and get to know the physical adsorption mechanism. 

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Comparison Table (Absorption Vs Adsorption)

Basic Terms Absorption Adsorption
Meaning Assimilation of ions, atoms, or molecules into the bulk of the solid or liquid phase Accumulation of ions, atoms, or molecules on the surface of the bulk of solid or liquid
Occurrence A bulk phenomenon A surface bulk phenomenon.
Heat Exchange Endothermic Process Exothermic process
Temperature Not affected by temperatures. Work well under low temperatures.
Concentration Constant throughout the medium Prone to changes in the bulk of absorbent.
Reaction Rate Uniform rate Increases slowly and attain equilibrium
Types Either physical or chemical Either chemisorption or physisorption 
Energy Ions or atoms get absorbed within the space of the absorbent. The adsorbate binds on the surface of the adsorbent by the interaction of van der wall forces or covalent bonds.
Limiting factors The flow rate in water, the composition of water, operating pressure, and temperature Time of contact, characteristic of adsorbent, the solubility of adsorbate, surface area, size, pH, and temperature
Application Refrigerants, cold storage, cooling system, and ice production Water purification, air conditioning, and synthetic resin

What is Absorption?

Absorption is a process where the ions, atoms, and molecules enter a bulk process whether in liquid or solid material.

Both absorbate and absorbent have no chemical relation. However, it is not easy to separate them in the long run once the process takes place.

The process is quite applicable in cooling systems, refrigerants, and cold storage. The usefulness of the process is the reason behind its popularity.

What is Adsorption?

Adsorption is a process where ions, atoms, and molecules of a substance adhere to the surface of another substance known as an absorbent.

Both absorbate and absorbent are loosely held hence can easily be separated. These substances can be group as physisorption and chemisorption.

Physisorption is a process whereby the interaction of the molecule on the surface is held together by weak van der wall force. Chemisorption is when they are held by a covalent bond.

The process is suitable in the manufacture of drugs, biochemical routines, air conditioning, water purification, and formation of the enzyme-substrate complex.

Main Difference Between Absorption and Adsorption 

  1. Absorption is the process whereby a substance is taken in the bulk of another substance whereas adsorption is the process whereby adsorbate sticks on the surface of the adsorbent.
  2. The reaction rate in absorption is endothermic and uniform while adsorption is exothermic and increases slowly to attain equilibrium.
  3. The concentration of absorbate in the absorption process remains constant throughout the medium while adsorbate in the adsorption process changes from bulk to the bottom of the adsorbent.
  4. Adsorption is affected by temperature and it works well under low temperature whereas absorption is not affected by temperature.
  5. The absorption process is applicable in Ice production, cooling systems, and cold storage while the adsorption process is applicable in air conditioning, water purification, and synthetic resin.
  6. The absorption is comparatively slower and equilibrium take more time to be attained whereas adsorption is rapid and equilibrium occur faster
  7. Absorption occurs at a uniform rate whereas adsorption increase steadily
  8. Absorption is a bulk phenomenon whereas adsorption is a surface phenomenon 
  9. The concentration of absorbate is the same throughout the absorbent in absorption whereas the concentration of adsorbate is more at the surface than other parts of the adsorbent in the adsorption

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Absorption and adsorption are two processes that are quite different when it comes to occurrence. You need to understand absorbent, absorbate, adsorbent, and adsorbate for proper differentiation. I hope the information on the difference between absorption and adsorption has been useful. 

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