AdvancedTopic 76 of 100Materials & Chemical
Adsorption
Molecules stick to solid surfaces, used for purification.
In depth
Molecules adhere to solid surfaces (physisorption weak, chemisorption strong). Isotherms: Langmuir q=q_max K C/(1+K C), Freundlich, BET. Adsorbents: activated carbon, zeolites, silica, alumina. Fixed beds are regenerated by temperature or pressure swing. Breakthrough curves define capacity.
Key points
- Surface area m²/g
- Pressure swing adsorption
- Mass transfer zone
ExampleActivated carbon filters remove organic impurities from water.
What is Adsorption?
Molecules stick to solid surfaces, used for purification.
Why is it important to understand adsorption?
Adsorption removes trace components and purifies gases and liquids, which is common in water treatment and air drying.
What is adsorption?
Molecules attach to the surface of a solid, usually through weak van der Waals forces, and the amount adsorbed depends on concentration and temperature.
How are adsorbents regenerated?
By lowering pressure, raising temperature or purging, which releases the adsorbed molecules so the bed can be reused.
How is Adsorption used in practice?
Typical applications include drying compressed air with a bed of silica gel, removing odours from a waste gas with activated carbon and purifying hydrogen with pressure swing adsorption.
What should I learn before Adsorption?
Study "Liquid-liquid extraction" first (topic 75 of 100 in Materials & Chemical). It covers the groundwork this topic builds on.
What are the key points of Adsorption?
Surface area m²/g. Pressure swing adsorption. Mass transfer zone.
Can you give an example of Adsorption?
Activated carbon filters remove organic impurities from water.
What comes after Adsorption?
The next topic is "Membrane separation", which builds directly on this one.
How difficult is Adsorption?
It is classed as Advanced in Materials & Chemical (topic 76 of 100). It is an advanced topic. It assumes you are comfortable with the intermediate topics in Materials & Chemical.