DMG is very good tool for Pd scavenging, but it does not work well in all circumstances.
I found that too much residual nitric acid tend to decompose DMG and forming Pd complex, so I always neutralized majority of free nitric in the solution using sodium hydroxide. pH must stay low tho. Aim for pH slightly above 0. Then, I usually filtered the solution from any undissolved junk and added DMG. You do not need to prepare a solution, if you have good mechanical/magnetic stirrer. Just add it in as powder with vigorous mixing.
Reaction of DMG with Pd in nitrate solutions is usually faster than in HCl solutions - DMG has somewhat better solubility in nitrate media in my experience. It can take one hour or even more to precipitate all of the Pd if solid DMG is used -- but I just usually let it stir and came back hour or two later to filter it.
That mixing and constant agitation is very important.
Never try to drop Pd with DMG from non de-NOx-ed AR solutions. DMG is severly decomposed in these, and precipitation is always incomplete. And in addition, decomposition products from DMG disintegration can be dangerous.
I always de-NOx-ed the solution, then dropped the gold, and finally scavenged Pd with DMG (AR solution, AuPd scrap). I just added some excess of it and let it stir vigorously overnight in a beaker on magnetic stirplate. Filter the precipitate in the morning, wash with some few % HCl...
I found that too much residual nitric acid tend to decompose DMG and forming Pd complex, so I always neutralized majority of free nitric in the solution using sodium hydroxide. pH must stay low tho. Aim for pH slightly above 0. Then, I usually filtered the solution from any undissolved junk and added DMG. You do not need to prepare a solution, if you have good mechanical/magnetic stirrer. Just add it in as powder with vigorous mixing.
Reaction of DMG with Pd in nitrate solutions is usually faster than in HCl solutions - DMG has somewhat better solubility in nitrate media in my experience. It can take one hour or even more to precipitate all of the Pd if solid DMG is used -- but I just usually let it stir and came back hour or two later to filter it.
That mixing and constant agitation is very important.
Never try to drop Pd with DMG from non de-NOx-ed AR solutions. DMG is severly decomposed in these, and precipitation is always incomplete. And in addition, decomposition products from DMG disintegration can be dangerous.
I always de-NOx-ed the solution, then dropped the gold, and finally scavenged Pd with DMG (AR solution, AuPd scrap). I just added some excess of it and let it stir vigorously overnight in a beaker on magnetic stirplate. Filter the precipitate in the morning, wash with some few % HCl...