Difference Between Adsorption and Absorption (With Table)

In chemistry, we study the different chemical properties and different processes by which two substances or compounds react to form a third product, and so on. Correspondingly, Adsorption and Absorption are other two different processes observed in our day-to-day life.

Adsorption vs Absorption

The main difference between Adsorption and Absorption is that Absorption is considered as a bulk phenomenon wherein substances are absorbed by an absorbent through the process of osmosis or diffusion. On the other hand, Adsorption is a surface-level phenomenon wherein the molecules stick on surfaces of other substances.

Adsorption is a surface-level phenomenon in which the adhesion of molecules plays a great role, molecules of the substance are stuck on the surface of other substances that can be liquid or solid and this process is called Adsorption.

Absorption can be a chemical process or a physical process wherein a substance enters the volume or bulk of another substance and this process is referred to as Absorption.The substance, which gets absorbed in this process is called absorbent and the substance, which absorbs is called absorbent.

Comparison Table Between Adsorption and Absorption

Parameters of ComparisonAdsorptionAbsorption
DefinitionAdsorption is an exothermic process in which molecules of substance stick on the surfaces of other substances.Absorption is the endothermic process in which substances enter another volume of most substances and absorption of substances takes place and it is defined as Absorption.
ConcentrationIn Adsorption, the concentration varies from the volume of the absorbent to the bottom.During Absorption, the concentration is constant and remains constant throughout the medium.
Rate Of ReactionThe rate of reaction in the Adsorption process increases slowly and achieves an equilibrium state.The rate of reaction is uniform throughout this process.
Temperature EffectThe Adsorption process occurs at a lower temperature.The Absorption process can occur at any temperature; it has no effect of temperature on the process.
ApplicationsThe Adsorption process is used in Air-conditioning, Water purification, And also use for chromatography for the separation of mixtures.The Absorption process is used in ice production and also in turbine inlet cooling.

What is Adsorption?

Adsorption is an exothermic process in which molecules of a substance stick to other substances. Adsorption is a surface phenomenon. Like surface tension, Adsorption is a result of surface energy. The Adsorption process is classified into physisorption and chemisorption.

In the process of Adsorption, Bulk of material substances, the affix requisite I.e ionic, covalent, or metallic of the essential atom in the material or substance is contented by the other atoms of the substance. However, atoms on the surface absorbent are not fully surrounded by other adsorbent atoms and In response to this, they can attract Adsorbates.

In Adsorption, the concentration varies from bulk to the bottom of the absorbent, and the rate of reaction in this process increases slowly and then lastly to an equilibrium state.

Adsorption is seen in natural physical as well as biological systems and is universally used in many industrial implementation processes I.e heterogeneous catalysts, also as activated charcoal, in water purification, chromatography for separation of mixtures, and also used in Air conditioning where waste heat is captured and using Adsorption chiller’s water is chilled with a sudden temperature change and thus used in air conditioning.

What is Absorption?

In chemistry, Absorption is described as the physical or chemical process in which substances enter another volume of the bulk of substances, it can be liquid or solid material and taken up by the volume and this process is called Absorption. Absorption is an endothermic process.

There are two types of Absorptions.

Chemical Absorption

Chemical Absorption occurs between adsorbate and the absorbent medium. Chemical Absorption relies on the concentration of reactants and even on the stoichiometry of the reaction.

Physical Absorption

In physical Absorption, Hydrophilic solids contain solids that can be readily absorbed by water. This interaction between water and other molecules of solid allows the separation of water into a solid, which further allows the absorption of water vapors even in low humidity.

The rate of reaction in Absorption is uniform throughout the reaction and the concentration remains constant throughout the entire process of Absorption. It can occur at any temperature as an option which usually occurs at a lower temperature.

Absorption occurs due to the appearance of empty spaces in the other molecules of the absorbent material. It is then filled with molecules and absorbs them, a process that can happen without or with energy.

Absorption takes place in all living and nonliving systems either to consume nutrients or to maintain healthy chemical and physical conditions in the human body. The absorption process is carried out for the production of ice, turbine inlet cooling, etc.

Main Differences Between Adsorption and Absorption

  1. Adsorption is a process in which substances enter another volume of bulk substances whereas Absorption is the process where molecules of substance stick to other substances.
  2. Adsorption is an exothermic process Whereas Absorption is an endothermic process.
  3. During Adsorption, the rate of reaction is uniform throughout the process. Wherein Absorption, the rate of reaction increases slowly until it reaches an equilibrium state.
  4. In the Adsorption process, the material remains attached to absorbent due to the presence of Van der Waal forces or due to covalent bonds. On the other hand in the Absorption process, the material remains in the absorbent material without causing any chemical reaction with the absorbent medium.
  5. Adsorption is used in carrying out air conditioning, water purification, etc. Where is absorption used in carrying out ice production and cleaning of turbine inlets.

Conclusion

The processes of Adsorption and Absorption sound similar, but they do so in different ways. Both processes are part of chemistry and can be observed in everyday life.

Adsorption is used in many industrially implemented processes such as heterogeneous catalysts, activated carbon, water purification, Adsorption for purification of gas mixtures, and ice production.

References

  1. https://iopscience.iop.org/article/10.1149/1.2108377/meta
  2. https://www.osti.gov/biblio/6910520