When I was preppin' for a separation of a THH zinc carbonate mixture I did some on-the-fly solubility tests using zinc sulfate as my zinc source to see how to most reliably prevent zinc precipitation.Jagube said:...Does this mean using ammonia for freebasing solves the potential cadmium contamination issue, as long as enough ammonia is used?
From memory, the more relevant results went like this:
Zinc sulfate solution slowly based with ammonia formed precipitate, which then dissolved with an obvious excess of ammonia.
Zinc sulfate solution containing 1% ammonium chloride behaved almost the same, but the precipitate redissolved a bit faster.
Zinc sulfate solution containing 5% ammonium chloride produced no precipitate on basing.
Ammonium sulfate was similarly effective at 5%
A fist full of ammonium salts should similarly prevent precipitation of cadmium.
A limitation is I did not do a test series using sodium carbonate as the basing agent, as it wasnt relevant to what I was doing at the time.
Ammonium chloride is cheap in feed stores, it prevents kidney stones in your pet goat.
Ammonium sulfate of very questionable purity is a common fertilizer chemical.

