Applications of Adsorption

  • Many applications are based on the phenomenon of adsorption. Some important applications of adsorption are as follows:

A) Applications of the Adsorption of Gases on Solids

i) For creating partial vacuum

  • The phenomenon of adsorption of gases on solids has been used for creating partial vacuum particularly at low temperature.
  • The vessel that has to be evacuated is connected to a narrow container containing activated animal charcoal which is dipped into liquid nitrogen.
  • At low temperature, the extent of adsorption of gases on solids is very high.
  • So, by the use of animal charcoal, the gases present in the vessel are adsorbed, and partial vacuum is created.

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ii) In gas masks

  • The inhalation of poisonous gases can be prevented using Gas masks.
  • The common form of gas masks contains a layer of activated charcoal.
  • The air that is inhaled must pass through this layer of activated charcoal.
  • The poisonous gases present in the air, such as chlorine, oxides of sulphur, carbon monoxide, etc., get adsorbed on the activated charcoal.
  • Thus, the inhaled air is freed from such toxic/poisonous gases.



iii) In heterogeneous catalysis

  • Most heterogeneous catalytic reactions initiate through the adsorption of gaseous reactants on solid catalyst. For example:
  1. Use of finely powdered nickel for the hydrogenation of oils.
  2. Use of finely divided vanadium pentoxide (V2O5) in the Contact Process for the manufacture of sulphuric acid.
  3. Use of Pt, Pd in many industrial processes as catalyst.

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iv) For desiccation or dehumidification

  • There are certain substances that have a strong tendency to adsorb water.
  • These substances can be used to reduce or remove water vapours present in the air.
  • Silica gel is used for dehumidification in electronic equipment.

B) Applications of Adsorption From Solutions

  • The phenomenon of adsorption from solutions has been used for many industrial or domestic applications. Some main applications are mentioned here below:

i) In dyeing

  • Many dyes get adsorbed on the cloth either directly or by the use of mordant.

ii) In removing colouring and odouring matter

  • The principle of adsorption is used in removing the undesirable colouring and odouring matter from the solutions or liquids.
  • From solutions of sugar and other organic liquids such as oils, etc., colouring matter is removed using activated charcoal.
  • Undesirable colouring/odouring matter from solutions or liquids can also be removed using Fuller’s earth.

iii) For recovery from industrial wastes/ mixtures

  • Components of mixture may be separated making use of the differences in the adsorption power of the various components of any mixture.
  • Adsorption provides an efficient method in concentrating the substances present in very dilute solutions.
  • The principle of adsorption is employed in several valuable recoveries made from the industrial wastes.

iv) For softening of water

  • Hard water can be softened by the use of ion exchange resins.
  • The use of these ion exchange resins is based on the selective adsorption from solutions.

v) Chromatographic analysis

  • The chromatographic technique depends on the principle of adsorption.
  • This technique is used for the identification/separation of various components of a mixture or solutions.

vi) Use of adsorption indicators

  • Many dyes can be used as adsorption indicator such as, fluorescein, in silver nitrate precipitation titrations.
  • At the completion of the titration, the ions produced by the dye in the solution get adsorbed onto the precipitates of silver halide, and undergo a colour change.





Applications of Adsorption