Precipitate the heavy metal from EDTA complex

[Jeffrop]

We want to precipitate the nickel ion from complex EDTA-nickel by hydroxide (OH from lime) but did not work ! The EDTA-Ni is so stable, Ni ion can not form a complex with OH to be precipitate ! !.

We try to break down the EDTA-Ni complex before precipitate by oxidation (HNO3/H2O2, Hypochlorite, O3/UV, thermal hydrolysis ..., ) but Ni can not be free from EDTA !

Any body who know how to precipitate the heavy metal from EDTA complex (EDTA-m) please let we know !!.

Thanks