36.6 |
Applications of Adsorption |
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The process of adsorption is very important as it has many applications in domestic as well as in industrial processes. Some of them are as follows: |
1. |
In heterogeneous catalysis: Surface active materials are widely used as catalysts mostly due to adsorption processes. If the surface active materials (adsorbents) have a different phase from that of substrates, then the catalysis is called heterogeneous catalysis. A system where both the catalyst and the substrate are in same phase is called homogeneous (catalysis). |
2. |
In removal of colouring material: Many coloured materials or impurities are removed through adsorption by suitable surface active materials like charcoal. Activated charcoal has been extensively used for this purpose. |
3. |
In ion exchange resins: Several polymeric materials are used for the separation of ionic substances in chromatography through ion-exchange.
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4. |
In adsorption indicators: Several dyes like eosin and fluoresein are used as indicators in the titrations of Cl -, Br - etc., against Ag +(Fajan’s method). |
5. |
In gas masks : Activated charcoal is used to remove toxic gases in gas masks. |
6. |
In dyeing of cloth: Many substances work as mordants for dyeing of cloths. Several metal cyanogen complexes and alums work as efficient mordants in dyeing cloths. |
7. |
In de humidizers: Many substances, when they adsorb water, change their colour. Silica and alumina gels are used as adsorbents for removing moisture. Silica is colourless but after adsorbing water becomes blue. |
