Question

Mention some important applications of adsorption.

Describe some important applications of the adsorption.

Answer 1

1. Removal of colouring matter: Adsorption is widely used to remove unwanted colour from raw sugar, juices, vegetable oils, and petroleum. Adsorbents such as activated charcoal or Fuller’s earth trap the colouring substances, aiding purification, especially in sugar manufacturing.
2. Dyeing: Dye molecules get adsorbed on vegetable or animal fibres. When mordants are used, the dye adsorbs on the mordant, which fixes the colour on the fabric.
3. Softening of hard water: Ion exchange resins selectively adsorb hardness-causing ions, like calcium (Ca²⁺) and magnesium (Mg²⁺), from water. Zeolites also adsorb these ions in the permutit process, thus softening the water.
4. Chromatography: The components of mixtures are separated by their selective adsorption on suitable adsorbents.
5. Precipitation titrations using adsorption indicators: Dyes such as fluorescein and eosin act as adsorption indicators by changing colour when adsorbed, which helps in detecting the end points of titrations.
6. Gas masks: These contain adsorbents that preferentially adsorb toxic gases, such as methane, chlorine, or sulfur dioxide, thereby purifying the air for breathing.
7. Production and preservation of high vacuum: The residual gases in evacuated vessels are adsorbed by materials such as activated charcoal or silica gel, which helps maintain high vacuum, as seen in Dewar flasks.
8. Catalysis: Solid catalysts adsorb gaseous reactants on their surfaces, increasing reactant concentrations at the catalyst surface and speeding up chemical reactions.
9. Controlling humidity: Silica gel adsorbs moisture, protecting delicate instruments from damage caused by humidity.
10. Separation of noble gases: The differences in the adsorption of noble gases on activated charcoal enable their separation.
11. Curing diseases: Certain drugs act by adsorbing harmful germs, which aids in treating diseases.
12. Froth flotation process: This process, generally used for concentrating sulphide ores, utilizes adsorption; pine oil adsorbs on ore particles, aiding froth formation and separation.