Factors affecting adsorption of gases on solids

Important Factors affecting adsorption of gases are

1. Nature of gas.
2. Nature of adsorbent.
3. Specific area of adsorbent.
4. Activation of the adsorbent.
5. Pressure of the gas.
6. Temperature

1. Nature of gas

Adsorption can be either physisorption or chemisorption. Chemical adsorption is highly specific, hence only a particular adsorbent can adsorb a gas. For example, Nitrogen is adsorbed by Iron. Adsorption of hydrogen by nickel or platinum.

But physisorption is not specific. In such cases it is observed that easily liquefiable gases are more adsorbed than permanent gases like He, N₂, O₂, H₂ etc. It is due to the reason that HCl, SO₂, CH₄, NH₃, SO₃ etc are more adsorbed. In case of easily liquefiable gases, van der Waals  force or molecular forces are more predominant, and hence physisorption becomes more significant.


2. Nature of adsorbent

The extent of adsorption depends on nature of the adsorbent. Charcoal and silica gel are good adsorbent for gases and moisture respectively. Similarly H₂ is strongly adsorbed by Ni.


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