I cant remeber exact volumes but it was minimal few mL per litre of each. There are a few papers on using this and other tergitol combinations. The order of addition makes no difference. However for best results it must be added before the reductant. I think both either end up washed out in the mother liquor and washings or burn off at low temperatures if adhered to the silver giving minimal carbon conatmination after firing.
Can I cement < 20 micron silver particles from silver nitrate using Copper? Do dispersants help?
- Thread starter baldwin_kevin
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baldwin_kevin
Member
This makes total sense, Platz. I will try the tergitol organic route after I experiment further with my purely inorganic physical constraints (stirring shear force, temperature, and dilution). FYI, I am planning to try one additional physical constraint, which I should have thought of, earlier: Using finely-divided copper as reductant instead of solid copper plate/bar. We'll see. My "known unknown" in this scenario is the possible hydrophobic nature of bare metals like copper when they are finely divided. Wetting agents might come into play at that point, so I might as well try tergitol organics with the copper reductant if I run into hydrophobic copper at the powder level.
Stirring will be the case - and also dilution. With high dilution and rapid stirring, particle size would be certainly smaller than from concentrated solutions staying still.
Cementing with powdered copper could definitely work - even without wetting agents. Be careful and be sure you use excess of silver in solution, to consume the copper as fully as possible
baldwin_kevin
Member
Hi, Orvi. Yes, thanks. I have already gotten some excellent results from high dilution with rapid stirring (in a low-ph solution, to boot). The mostly-fine particle sizes were only ruined by crusts of solid silver metal that preferentially formed in the lee of the copper bar where the fluid shear was not strong. Regarding your suggestion to "use excess of silver in solution," I have already wondered how visual inspection might be able to tell how much copper powder was still in suspension. There should be a slight color shift as copper powder gives way to silver powder.Stirring will be the case - and also dilution. With high dilution and rapid stirring, particle size would be certainly smaller than from concentrated solutions staying still.
Cementing with powdered copper could definitely work - even without wetting agents. Be careful and be sure you use excess of silver in solution, to consume the copper as fully as possible
I don't know if you would be able to detect copper in suspension by color, but you could test the precipitated silver. Take a small sample of the silver cement and add a small amount of nitric acid. Any copper in the cement should give a blue tint to the acid.
If you're in doubt as to whether you're really seeing a blue tint, take a couple drops of the acid solution and add a few drops of ammonia. If there is copper, the blue color will intensify. Be sure to promptly reacidify the test sample to avoid creating any explosive compounds.
Dave
If you're in doubt as to whether you're really seeing a blue tint, take a couple drops of the acid solution and add a few drops of ammonia. If there is copper, the blue color will intensify. Be sure to promptly reacidify the test sample to avoid creating any explosive compounds.
Dave
Google Peter Scales. He has at least one patent in this area.
baldwin_kevin
Member
Thanks for the pro tip, Dave, with the nitric acid and ammonia tests. Also, not blowing up (accidental silver fulminate, I imagine.) --K
kurtak
Well-known member
Just to clarify - silver fulminate can be unintentionally made by adding alcohol to a silver nitrate solution due to a CNO ion (fulminate ion) being attached to an Ag ion --- Silver fulminate = AgCNO
There are a number of other silver explosive compounds that exist &/or can be created
Examples - silver nitride - silver azide - silver acetylide --- these silver explosive compounds are sometime referred to as "fulminating" silver - which is not the same thing as silver fulminate
Silver nitride is created when silver is complexed with ammonia ------
Silver nitride - Wikipedia
Kurt
baldwin_kevin
Member
Thank you, kurtak, for these important safety distinctions. I did not know. --K
erischilde
New member
Been digging around the internets. Thank you so much for your knowledge on this other person's post.
