Alumina (Al2O3)
Alumina is also known as aluminum oxide. If you talk about alumina you can compare it with charcoal. First of all, you need to activate the alumina to increase the surface area by increasing its porosity.
Methods of activation of alumina
- Physical
- Chemical
Applications
- Adsorption of heavy metals like arsenic from liquid and gases.
Regeneration
- It is possible by burning the alumina at a high temperature between 3000C to 4000C
Comparison between activated charcoal and activated alumina
| Activated charcoal | Activated alumina |
| 1 gm of activated charcoal has more than 3000 m2 surface area. | 1 gm of activated alumina has more than 200 m2 surface area. |
| Used to filter volatile organic compounds such as acetic acid, ethanol, and also chlorine from the fluid | Used to filter heavy metals such as arsenic from the fluid |
| Cannot be regenerated | Can be regenerated |
Zeolite( Al2SiO5)
It is a naturally occurring, crystalline, microporous compound. Nowadays, these compounds are also synthesized to form a powder.
Working mechanism
It is based on the process of adsorption. When gas or liquid passes through the zeolite surface, smaller sized molecules pass through the surface while larger sized molecules are adsorbed by the surface.
Types
There are more than 50 types of zeolites. Some of them are stated below
- Clinoptilolite
- Mordenite
- Phillipsite
Applications
- Adsorption
- Ion exchange
Zeolite for adsorption (in oxygen concentrator)
Zeolite is the major source of filtration in oxygen concentration. The most widely used zeolite for the oxygen concentrator is zeolite 13X. You will find zeolite inside two of the zeolite towers. When you open an oxygen concentration and see inside, you will find two vertical towers that store zeolite powder.
When compressed air is passed through zeolite powder, oxygen passes through it. Other gasses such as nitrogen and argon having higher molecular size gets adsorbed by the power.
Life span
Generally, the life span of zeolite powder is above 2 years (in the case of an oxygen concentrator).
