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Ted Mooney, P.E. RET

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Thread 105/68

Circumstances leading to formation of salt

Dear Sir,

Can you help me regarding the circumstances leading to formation of such salt. I am trying to treat a wastewater containing "Fluoride". If I can make such salt or sodium based insoluble salt then it will be of great help.

Thank you,

SK JHA
- Baroda, Gujarat, India
publicly reply to SK JHA

A "standard" treatment is precipitation with lime, forming calcium fluoride. The problem is that the solubility of calcium fluoride is probably much higher than you'd like it to be, so that if you are trying to meet an effluent standard you're probably out of luck. You may need to go to ion exchange.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
publicly reply to Ted Mooney

About the circumstances leading to the formation of Fluoride salts, I can't help you because I don't know your process. I can only say that a Calcium salt (like Calcium Chloride) transform Fluorides in CaF2 completely insoluble in water. Also Barium salts work.

Regards

Francesco Cicchetti
- Sulmona, Italy
publicly reply to Francesco Cicchetti

Oops,

Barium Fluoride solubility is 1.2 g/l, while Calcium Fluoride is virtually insoluble (Kps = 5 * 10Exp -11), but you should verify how many ppm are left after precipitation. Sorry for the mistake!

Francesco Cicchetti
- Sulmona, Italy
publicly reply to Francesco Cicchetti

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