Defluorination Application Of Activated Alumina
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Defluorination Application Of Activated Alumina

Views: 0     Author: Site Editor     Publish Time: 2023-04-29      Origin: Site

One of popular usage of CHEMXIN activated alumina material is as a water filter to remove or reduce contaminants like fluoride, selenium, and arsenic from water, which is widely used in water treatment applications for home, commercial, and industrial.

This application is similar to anion-exchange resin, but the removal of fluoride is larger than anion resin. When the PH value of raw water is low, the defluorination capacity of Activated alumina is high (≥2.5-3.0mg/g), and it has a large surface area of more than 300 m2 per gram due to lots of microscopic pores, meaning that it has strong adsorption and defluorination capacity.

Chemical formula Of Defluorination :

(Al2O3)n·2H2O + SO4 →(Al2O3)n·H2SO4 + 2OH

(Al2O3)n·H2SO4 + 2F → (Al2O3)n·2HF + SO4


Attention 3 points in the usage process:

1.Please adjust the PH value to around 5.5 for the best fluoride removal environment when put the raw water into the machine.

2.Adding acidic solutions such as sulfuric acid, hydrochloric acid, acetic acid, or carbon dioxide gas to reduce the PH value. The dosage based on the alkalinity, PH value or test data.

3.When the defluorination effect of Activated alumina decrease with yellow brown appearance that means it has been polluted with impurities of water. Hence, it is better to dispose of it with 3% diluted hydrochloric acid every six months, and the operation method is the same as the regeneration.

How to Restore Activated Alumina Adsorption Efficiency?

1.Regenerating with aluminum sulfate: the concentration is 2% to 3%, and the amount of aluminum sulfate can be calculated based on “60-80g of solid aluminum sulfate (AL2 (sO4) 3-18h2O) is required for removing 1g of fluoride”, The regeneration time around 2-3 hours, and the flow rate roughly 1-2.5m/h. The regenerated solution in the filter must be removed after finish the regeneration process.

2.Regenerating with sodium hydroxide (NAOH): the concentration is o.75% to 1%, and the amount of aluminum sulfate can be calculated based on “8-10g of solid NAOH is required for removing 1g of fluoride”, the quantity of regeneration liquid is 3-6 times of alumina beads, the regeneration time around 1-2 hours, and the flow rate roughly 3-10m/h. The filter layer is alkaline after regeneration, it must be converted to acidic to remove F-ions from the water.

Chemical formula Of Regeneration :

(Al2O3)n·2HF + SO4 →(Al2O3)n·H2SO4 + 2F

activated alumina_01

In addition to the function of fluoride removal, activated alumina is commonly used as a desiccant to adsorb water molecules in the air or gases to keep things dry and reduce the humidity level. CHEMXIN is one of the biggest leading manufacturer of activated alumina adsorbents in China since 2002. Our factory covers an area of 50,000M2 and have own R&D team.

Want to know more about activated alumina and our company? Kindly contact us any time:



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