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Activation of Aluminum Oxide (Alumina)


scotty

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Hi All, so, I'm not even a science novice lol I just have scoured Google for my answer and come up blank. I was hoping you guys could help?

So I've seen the chemical process of how Aluminum Oxide is made, but little information can be found about it's activation.

Fluoride is a major problem in India and activated alumina is widely used to treat their drinking water, so some info can be found from them.

They reactivate it every 3 months using this method:

 

*Mix 8 liters of clean water with 80 grams of sodium hydroxide (Lye) in a bucket, leave for 8 hours
*Then Clean with 8 buckets of clean water
*Mix 8 liters of clean water with 80 ml of Sulphuric Acid, leave for 8 hours
*Then Clean with 8 buckets of clean water
I have also seen that, when used as a desiccant, you can reheat the media to 200 degrees celsius to regenerate it.
My questions are:
1. Is the base/acid re-activation process the only one?
and
2. What exactly happens, chemically, when the aluminum oxide is activated? What makes it activated?
3. Would you imagine that there is a cheaper way to reactivate A.O. on a global scale for filtering fluoride and arsenic?
Thanks!
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They reactivate it every 3 months using this method:

 

*Mix 8 liters of clean water with 80 grams of sodium hydroxide (Lye) in a bucket, leave for 8 hours

*Then Clean with 8 buckets of clean water

*Mix 8 liters of clean water with 80 ml of Sulphuric Acid, leave for 8 hours

*Then Clean with 8 buckets of clean water

Where do you have Aluminium in this description?

 

Sodium Hydroxide + Aluminium or Aluminium Oxide or Aluminium Hydroxide gives Sodium Aluminate.

https://en.wikipedia.org/wiki/Sodium_aluminate

Quote

"In water treatment it is used as an adjunct to water softening systems, as a coagulant aid to improve flocculation, and for removing dissolved silica and phosphates."

 

Sodium Aluminate + Sulfuric Acid gives Aluminium Sulfate.

https://en.wikipedia.org/wiki/Aluminium_sulfate

Quote from above website:

"Aluminium sulfate is used in water purification and as a mordant in dyeing and printing textiles. In water purification, it causes impurities to coagulate into larger particles and then settle to the bottom of the container (or be filtered out) more easily. This process is called coagulation or flocculation. Research suggests that in Australia, aluminium sulfate used this way in drinking water treatment is the primary source of hydrogen sulfide gas in sanitary sewer systems.[6] Improper and excess application polluted the water supply of Camelford in Cornwall."

 

Coagulation

https://en.wikipedia.org/wiki/Coagulation

 

Flocculation

https://en.wikipedia.org/wiki/Flocculation

Edited by Sensei
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Where do you have Aluminium in this description?

 

 

There's no reason why he would have aluminium in there.

It's implied that the alumina is reactivated by soaking it in sodium hydroxide solution, then rinsing that off (carrying the fluoride with it) and then re-acidifying it.

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