From Sodium Nitrite

[SilverNitrate]

I have been using sodium nitrite to drop gold from a solution that contains appx 50% Au / 50% Cu ions. It works quite quickly however may have to wait a full day for the gold to settle. I tend to neutralize by titrating with either NaOH or NaHCO3 in solution or even as a mixture of NaOH and NaNO2 in water to titrate out the gold. Since I do it this way I get a good handle on the NOx that it generated. However it drops gold as a dark brown mass but upon drying it becomes quite tan-yellow. in this pic as the gold is drying and possibly sintering nano-particles it becomes a more recognizable color.
[img:1200:1600]http://www.gholar.com/images/gold-filh.jpg[/img]

 

[SilverNitrate]

Gold will drop using NaNO2 regardless if the Au/AR solution is strongly acidic or neutralized, however much more NaNO2 is needed if its acidic as the NaNO2 neutralizes the acids of the AR before the gold drops. This also makes forth a frothy mess, and not wise for large batches of AR.

A good quality appearencewise is if you partly neutralize with NaOH stop before any apparent change, then finish with NaHCO3 allow to set, then drop with the NaNO2.

titrate with no apparent change
[img:1200:1600]http://www.gholar.com/images/gold-file.jpg[/img]
titrated with apparent change
[img:1200:1600]http://www.gholar.com/images/gold-filf.jpg[/img]

 

[OMG]

That's interesting.
That kind of looks like a 5gal bucket in the first pic!!! :shock:

 

[SilverNitrate]

That's interesting.
That kind of looks like a 5gal bucket in the first pic!!! :shock:

'll be nice, about 20g drying in a small lab casserole. The other pix have about 50g Au in solutions inside a 3k ml reaction pot.