Question

How is fluorine separated from other materials found with it?

Answer 1

The following processes are used for fluorine removal:

1.      filtration through activated alumina- this is the most widely used process

2.      coagulation-flocculation – or aluminum sulphate treatment - can only be used on raw water that requires sedimentation and that has low fluoride content.

3.      lime used to soften water -This method can be used but with a pH >10 and provided that the water has a sufficient magnesium level (high) because it is the magnesium oxide that will adsorb the fluorine. Approximately 50 mg · L–1 of magnesium is required to remove 1 mg · L–1 of fluorine.

4.      using tricalcium phosphate

5.      other processes

·         reverse osmosis

·         Electrodialysis