Activated alumina is a significant segment in the non-metallurgical alumina industry. It refers to transitional phase alumina such as γ, κ, θ, η, δ, χ, and alumina compounds with partial hydration (Al2O3·nH2O, 0≦n﹤1). These aluminas share common features: large surface area, porous structure, and well-distributed pore sizes.

Uses:
Activated alumina can be categorized into adsorbents, desiccants, and catalyst carriers. It finds applications in pharmaceuticals, chemical processing, metallurgy, water purification, chemical analysis, and waste gas treatment. Its usage continues to expand with technological advancements.

Properties of Activated Alumina:

1. Surface Area:
The primary parameters are surface area and pore size distribution. By selecting different raw materials, various surface areas can be achieved. Additives can alter pore size distribution. Under controlled conditions, surface areas up to 600m²/g are attainable.

2.Pore Size Distribution:
The pore size varies with the type of Al(OH)3 used. Medium pore sizes are typically achieved with pure aluminum hydroxide, while smaller or larger pores can be obtained by using aluminum gels or adding organic materials during production.

Classification:

1.γ-Series, Low-Temperature Alumina:
Formed below 600°C, includes ρ, χ, η, and γ aluminas with poor crystallinity.

2.δ-Series, High-Temperature Alumina:
Produced between 800°C and 1000°C, includes κ, θ, and δ aluminas with better crystallinity.

3.ρ-Alumina:
An amorphous form resulting from rapid dehydration of gibbsite, notable for its rehydration properties, enabling the production of various activated alumina products.

Applications:

Activated alumina, a white spherical material, is used in drying gas and liquid phases in industries like petroleum, chemical, and electronics. It also serves as a catalyst and catalyst carrier, and is effective in defluoridation, acid removal from transformer oil, and as a deep-drying agent for gases.

Factors Affecting Adsorption Performance:

• Particle Size: Smaller sizes increase capacity but reduce strength.
• pH Level: Lower pH enhances adsorption when above pH 5.
• Fluoride Concentration: Higher initial fluoride increases capacity.
• Alkalinity: High bicarbonate concentration reduces capacity.
• Ions: Chloride and sulfate ions, and arsenic presence affect performance.

Activated alumina is ideal for use in heatless regeneration systems due to its high adsorption capacity and stability.