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seperating metal ions by precipitation


I have no ideal on this question?  an industrial plant that specializes in cleaning up waste liquids is confronted with a problem of seperating the metal ions found in a large vat of solution. By analysis the solution was found to contain varying quantities of silver, barium, and ions (iii) ions suggest a procedure for seperating the metal ions by precipitation   Can anyone suggest anything?


Donaldson Tan:
Removal of Ag and Barium ions via precipitation. Hydroxides of both metal are water-insoluble. Perhaps intro excess aq. ammonia into the waste liquid. This should remove both the silver and barium ions without introducing another metal ion into the waste liquid.

Barium hydroxide is somewhat soluble in water.  I would suggest adding sodium sulfate, which will crash out nearly all the barium ions and some of the silver ions as the sulfate salts.  Then add iodide to precipitate out any remaining silver.  Adding hydroxide as well as ammonia to a silver solution may not be the smartest thing in the world; depending on other contaminants, you could wind up with an explosion.


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