Activated Alumina is a porous material with γ-Al₂O₃ or η-Al₂O₃ as the main crystal phase. With its unique physical and chemical characteristics, it has shown significant advantages in the field of adsorption.

The mechanism of activated alumina adsorption: physical and chemical synergistic effect

1. Physical adsorption of activated alumina

Van der Waals's power leads: The porous structure of activated alumina (specific surface area 200-400 m²/g, pore size 2-50 nm) provides a large number of adsorption sites, and captures polar molecules such as water vapor and CO₂ through intermolecular forces.

Reversible and fast: The adsorption process is not selective, but has a fast speed (in contact, adsorption), low heat release (close to condensation heat), suitable for dynamic adsorption scenarios (such as gas drying).

2. Chemical adsorption of activated alumina

surfactant groups of activated alumina: hydroxyl groups (OH⁻) and alumina groups (Al-O⁻) form chemical bonds with adsorbents. For example, during the fluorine removal process, F⁻ replaces SO₄²⁻ by ion exchange (after treatment of Al₂(SO₄)₃), thereby achieving selective removal.

Lewis acidic site: After adsorbing water molecules, oxygen ions and incomplete aluminum ions are formed, enhancing the affinity for polar substances.

3. Selective adsorption of activated alumina

Polarity priority: It has strong adsorption ability to water and ethanol and weak adsorption of non-polar organic matter.

Ion exchange sequence: Under acidic conditions, the anion adsorption priority is OH⁻ > PO₄³⁻ > F⁻ > SO₄²⁻ > Cl⁻, which can optimize selectivity by adjusting pH.