Activated alumina can adsorb not only water but also a variety of polar and polarizable molecules, which extends its applications far beyond its use as a drying agent.
The main categories of substances that activated alumina can adsorb are as follows:
1. Polar Molecules
This is the type of molecule that activated alumina is most proficient at adsorbing. Due to the acidic sites and strong electrostatic field on its surface, it has a strong affinity for molecules with lone electron pairs or a dipole moment.
Fluoride Ions (F⁻): This is a crucial application in water treatment. Through ion exchange and ligand exchange, activated alumina efficiently removes excess fluoride from drinking water, helping to prevent endemic diseases like dental fluorosis.
Sulfur Compounds: Such as hydrogen sulfide (H₂S), mercaptans (e.g., methyl mercaptan), and sulfur dioxide (SO₂). It is used for purifying natural gas, refinery gas, and various industrial gases to remove odorous and corrosive components.
Chlorine Compounds: Such as hydrogen chloride (HCl). It is used to remove corrosive hydrogen chloride in petrochemical processes.
Oxygenated Organic Compounds: Such as alcohols, phenols, and aldehydes. It can be used for solvent recovery or waste gas treatment.
2. Unsaturated Hydrocarbons
Activated alumina has a certain adsorption capacity for molecules containing π-bonds.
Olefins (e.g., ethylene, propylene): Its selective adsorption can be utilized to separate olefins from saturated alkanes in gas mixtures.
3. Acidic Substances
Utilizing its amphoteric nature (can act as either a weak acid or a weak base), activated alumina can adsorb some acidic substances.
Arsenates and Arsenites: In water treatment, it can effectively remove arsenic from water, making it an important material for arsenic removal.
This broad selective adsorption capability, combined with its high mechanical strength and thermal stability, forms the cornerstone of activated alumina‘s role as a versatile adsorption and purification material.
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Post time: Oct-23-2025