What is Activated Alumina?
Activated alumina (AA) is a porous, solid form of aluminium oxide (known as Al2O3 or alumina) and is the same mineral that makes up precious gems such as rubies and sapphires. The impurities in the precious gems are the source of the stones’ bright colours. AA is found in the ground, once it has been evacuated, all the existing moisture is removed by heating it to a very high temperature. This process leaves a high surface area and lots and lots of pores. These pores in the material allow it to absorb water and to pass, while other molecules are traped in place.
What is Activated Alumina used for?
AA can be used for many different applications, one of the most important is being desiccation (the adsorption of water). AA as a desiccant can be used to dry compressed air and other types of gas and also used to dry liquid stream.
Additionally, AA (as an adsorbent) is often used to purify gas streams by the selective adsorption of specific molecules. AA can be used for water filtration attributes, filtering fluoride, arsenic and selenium in drinking water. It can also be used as a catalyst in the Claus process, (a desulfurizing treatment for natural gas0.
What shapes does Activated Alumina come in?
AA normally come in round beads. Beads range in diameter from 1.6mm (1/16″), 3.2mm (1/8″), 4.8mm (3/16″) to 6.4mm (1/4″).
The AA used in the Ultrastream water filtration system (see image above) has been additionally refined (heat-treated again) to remove any residue resins. It is also in chip form. This is to increase the amounts of media that can fit within the available space and to increase the amount of surface to water that comes in contact with. This allows the media to capture more of the contaminants in the water.
Extract from Activated Alumina Grand View Research article
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Extract from Wikipedia…
Activated alumina is manufactured from aluminium hydroxide by dehydroxylating it in a way that produces a highly porous material; this material can have a surface area significantly over 200 m²/g. The compound is used as a desiccant (to keep things dry by absorbing water from the air) and as a filter of fluoride, arsenic and selenium in drinking water. It is made of aluminium oxide (alumina; Al2O3). It has a very high surface-area-to-weight ratio, due to the many “tunnel-like” pores that it has. Activated alumina in its phase composition can be represented only by metastable forms (gamma-Al2O3 etc.). Corundum (alpha-Al2O3), the only stable form of aluminium oxide, does not have such a chemically active surface and is not used as a sorbent…
Extract from Grand View Research article…
Activated Alumina Market Worth $1.32 Billion By 2025 | CAGR: 5.4%
… It is highly porous and exhibits tremendous surface area, which results in superior adsorbent capabilities. In addition, the product is resistant to thermal shock and abrasion and does not shrink, soften, swell, or disintegrate when immersed in water. Shrinking freshwater reserves coupled with rising demand for water supply is expected to drive the water treatment sector over the coming years. Various government agencies are looking for effective ways to meet the cumulative need for regular water supply. The drive to create a sustainable water treatment environment is expected to positively influence the product demand over the forecast period.
The product is used as an adsorbent in water treatment for fluoride removal. Fluoride is the waste that is associated with the production of fertilizers, pesticides, semiconductors and steel and aluminium. The U.S. Environmental Protection Agency (EPA) has established the maximum contaminant amount of fluoride in water at 4ppm. Activated alumina can reduce these levels even further, thus, it is preferred over other methods of fluoride removal. Asia Pacific led the global market and is likely to continue its dominance over the forecast period. Rapidly growing end-use industries in the region is the major factor driving the market…
Read the full article – Grand View Research on Activated Alumina – June 2019