Melgar
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Could Devarda's alloy (link in post) be used to remove the nitrates from an aqua regia solution?
Presumably, this reagent will reduce nitrates to ammonia. Incidentally, one of the problems with extracting precious metals from aqua regia is that
if you have ANY nitrate ions left, then when you add HCl to dissolve the base metals, you just form aqua regia again, and dissolve a portion of your
precious metals.
https://en.wikipedia.org/wiki/Devarda%27s_alloy
Usually, they just make sure to wash their precipitates really well before dissolving the base metals, and there's always the SnCl2 test to make sure
they got it all, but I've definitely had nitrates in solution that I've neede removed for one reason or another. Any downsides to using this method,
besides that it might reduce everything else too, and requires a strong base to work? This seems weird, incidentally, because you're turning an acid
into a base in a baic solution. I've removed all the metals in the alloy from solution before, but not so much the nitrates. Unless of course,
there's an easier way.
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morsagh
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There's written "under alkaline conditions". I don't know if this reduction will work in acidic solution because redox pottential of aluminium in acid
is less negative than in basic.
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j_sum1
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I have some Devarda's alloy to get rid of (unopened in original container -- two 50g bottles available.) There was another SM member interested but I
am waiting for him to get back to me. U2U if interested.
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