SilverNitrate
Well-known member
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]
[img:1200:1600]http://www.gholar.com/images/gold-filh.jpg[/img]