Activated alumina is a porous oxide made by high-temperature dehydration of aluminum hydroxide. It has a high specific surface area, abundant surface hydroxyl groups and adjustable pore size distribution, making it an ideal adsorption material. Compared with ordinary alumina, activated alumina has a higher adsorption capacity and can be regenerated and reused, playing an important role in environmental governance and industrial production.
Adsorption mechanism of activated alumina
- Physical adsorption: Adsorption of gas molecules (such as H₂O, CO₂) by van der Waals forces.
- Chemical adsorption: Coordination or ion exchange with pollutants (such as F⁻, heavy metal ions) through surface hydroxyl groups.
- Electrostatic adsorption: In solution, changes in surface charge affect the adsorption of charged ions.
Main applications of activated alumina
- Water treatment
(1) High-efficiency fluorine removal
- Performance: adsorption capacity can reach 15-30 mg F⁻/g, suitable for drinking water and industrial wastewater treatment.
(2) Heavy metal removal
- Target pollutants: As³⁺/⁵⁺, Pb²⁺, Cd²⁺, Cr⁶⁺, etc.
(3) Organic pollutant adsorption
- Application: Removal of dyes, phenols and pesticide residues.
- Gas purification and drying
- Industrial gas drying: deep dehydration, used in air separation, natural gas and refrigeration systems.
- Acid gas adsorption: removal of H₂S, SO₂, etc., to protect downstream equipment.
- VOCs treatment: has adsorption potential for volatile organic compounds such as benzene and formaldehyde.
- Petrochemical and catalysis
- Catalyst carrier: used in reactions such as hydrodesulfurization and Fischer-Tropsch synthesis to load active components.
- Oil refining: absorb acidic substances and colloids in lubricating oil to extend service life.
- Chromatographic separation and medicine
- Chromatographic filler: separate polar compounds such as alkaloids and steroids.
- Drug carrier: used for purification and sustained-release preparation of antibiotics.
The above are the main applications of activated alumina as an adsorbent. Activated alumina plays an irreplaceable role in water treatment, gas purification, chemical catalysis and other fields due to its excellent adsorption performance, stability and economy. In the future, through the integration of nanotechnology, surface modification and intelligent regeneration process, its application scope will be further expanded.