- Adsorption is the phenomenon of adherence where a particular substance is held to the surface of another solid substance. Substance that is adsorbed is called adsorbate and the solid that adsorb is called adsorbing material or adsorbent. (e.g. charcoal, silica gel).
- Adsorption and absorption both are applied to solids, but the former refers to an excess concentration of substance at the surface of solid and the latter implies to penetration of the solid by a given substance.
- The amount of adsorbate adsorbed to an adsorbent depends on
- Total surface area expressed by the adsorbent.
- Nature of adsorbent and adsorbate.
Importance of adsorption:
- Widely used in chromatographic techniques for separation, purification and analysis of various substances, e.g. Adsorption chromatography, Ion exchange chromatography.
- In biological system hydrophilic(water soluble) substances are adsorbed around hydrophobic (water insoluble) substances to keep the hydrophobic substances in solution and to prevent their precipitation.
- Purification of solutions of different substances by removing unwanted substances(adsorbates) with the help of adsorbents.
- e.g. Charcoal as adsorbent can remove dyestuffs and other unwanted substances from solution.
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