Activated alumina is a porous, highly dispersed solid material with a large specific surface area, excellent adsorption properties, surface acidity, and thermal stability. These properties make it a key material in various environmental protection fields.
Contributions to Water Treatment
Fluoride Removal: In high-fluoride areas, excessive fluoride in drinking water can lead to health problems such as dental fluorosis and skeletal fluorosis. Activated alumina is a highly effective and economical adsorbent for fluoride removal. It selectively adsorbs fluoride ions from water, significantly reducing the fluoride content in drinking water through simple filtration, ensuring safe drinking water for millions of people.
Removal of Heavy Metals and Other Pollutants: In addition to fluoride, activated alumina can also effectively adsorb harmful heavy metal ions such as arsenic, lead, and chromium, as well as phosphorus. Activated alumina is a key treatment medium for treating industrial wastewater, particularly heavy metal-containing wastewater from the metallurgical and electroplating industries.
Contributions to Air Pollution Control
Volatile Organic Compound (VOC) Adsorption and Recovery: Industries such as petrochemicals, spray painting, and printing generate large quantities of VOCs. These substances are important precursors to PM2.5 and ozone, posing significant risks to the environment and human health. Activated alumina, due to its large surface area and pore structure, is often used as an adsorbent or catalyst support to adsorb and concentrate VOCs or catalytically combust them, converting them into harmless carbon dioxide and water.
Acidic Gas Purification: Coal combustion and waste incineration generate acidic gases such as sulfur dioxide, hydrogen chloride (HCl), and hydrogen fluoride. Activated alumina can be used as an adsorbent or reaction medium in dry scrubbers to effectively remove these major pollutants that contribute to acid rain.
Indirect Contributions as a Catalyst Support
Activated alumina is chemically stable, with acidic sites and a rich pore structure on its surface. Many highly effective, environmentally friendly catalysts are supported on activated alumina. For example, the catalyst in an automotive three-way catalytic converter is supported on a honeycomb-shaped cordierite carrier, which is typically coated with a layer of gamma-alumina (a type of activated alumina). This "activated alumina coating" significantly increases the catalyst's dispersion and effective reaction area.
Advantages and Features
High adsorption capacity: Specific adsorption capacity for fluorine, arsenic, and other substances.
High mechanical strength: Resists pulverization and offers a long service life.
Excellent thermal stability: Maintains structural and performance stability at elevated temperatures, crucial for catalytic applications.
Chemical inertness: Unreactive with most substances, ensuring stable properties.
Renewability: After adsorption saturation, the material can be regenerated and reused using appropriate methods, ensuring economical and environmental protection.
