- 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.
Image Source: Researchgate
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:
- Use of finely powdered nickel for the hydrogenation of oils.
- Use of finely divided vanadium pentoxide (V2O5) in the Contact Process for the manufacture of sulphuric acid.
- Use of Pt, Pd in many industrial processes as catalyst.
Image source: Toppr
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