Another odd reaction... Distilled water into silver nitrate

[RicXX]

Hey all, another quandary, this time it is a "what did I do wrong?"

Start with what I am doing (photos to follow) (Now I dont know why my photos have rotated 90*... Im so done with today!!!)

Making a batch of electrolyte for my silver cell, had a micro 1L cell, upgrading to a small 3L cell so followed the same processes just larger quantity as I have before...

Ingredients:
500g pure silver powder
500ml distilled water
400ml nitric (yes I know not the correct ratio but read on)

I preheat the water in the microwave, add it to the silver in the clean Pyrex pot, put pot on burner to heat some more, add 100ml nitric, wait for fumes to die off, stir with glass rod, add 100ml nitric, fumes, stir, 50ml repeat...
400 ml in, no more fumes, bring to boil, let cool, filter off top portion, nice pale green... 750-800ml ish, make note to add distilled...

Add 200ml distilled to remaining, heat till light steam, add 100ml nitric, fumes, stir, 100 ml nitric, fumes, stir, wait... still some remaining silver, add 50ml, up heat, fumes... very little silver left, boil for 30ish mins, add 200ml distilled to assist in cooling, filter cold solution, rinse filter, bit lighter pale green, add to first batch...

Need to add distilled to dilute for the cell... this is where it goes awry... Distilled hits the nitric and goes brown and floats... pic 1





I decided to filter it to see what comes out... This is the same distilled I have used for the refining and washing of the filters...





I didnt just pour it all in, I just poured till all the dark water was gone...



My only thought was that there may have been too much free nitric and it had a reaction? No Fumes, the dark stuff just floated there split like that... currently waiting to see if it will settle in the flask, whats in the filter I dont know but its brownish...

Anything anyone can suggest would be greatly appreciated, Im starting to wonder if I missed a step somewhere...

 

[FrugalRefiner]

What is the source of your silver? Pure silver dissolved in nitric should be nearly colorless.

Dave

 

[RicXX]

Its stirling that I recovered before, dropped, washed several times, and dried... generally when I start a new batch its this pale green, till I do a batch with silver from the cell, then its pretty clear... I didnt keep enough from my last harvest from my 1L cell to make a clean batch...

 

[Harold_V]

Silver recovered with copper won't be pure, and your results reflect that fact.
I had a policy of reserving the last removal of silver from my silver cell to be used in making the next batch of electrolyte. I operated my silver cell on a continual basis, until I'd parted all of the anodes I'd accumulated. There's method to my madness, which I'll explain.

If the silver used in making electrolyte yields anything more colorful than an almost colorless solution, especially after heating to a low boil, there's something present besides silver. By using the last silver recovered in the cell, I verified that I was depositing only silver, no copper, no palladium. My electrolyte, while still concentrated, after boiling, was just a hint of yellow, and became pretty much colorless when I added the required amount of distilled water. I always diluted the resulting solution, as allowed to cool, it grew immense silver nitrate crystals if not diluted.

The boiling process, in my experience, served to expel any traces of those nasty brown fumes, which, mixed with silver and copper, make a green solution. Also take note that when you have a green tint, you may also have platinum and/or palladium present, so test for each any time you have discoloration. If you process dental materials, it's almost impossible to avoid both of them, as silver becomes the carrier.

Harold

 

[RicXX]

The question is why would adding distilled water to dilute the solution further have the results in the photos?

With seeing the pale green colour (it looks deeper in the photo) I figured there was a little copper in it, but figured it would due for a first run, then can re run the formed crystals in the next batch of electrolyte... I have a couple kilos of silver shot to run through the cell, so figured I would run it a couple of times to make sure its all clean.

 

[RicXX]

Ok well while cleaning up some of my beakers and filters, I sprayed with a cleaner that contains bleach... instantly there was black soot in the sink, and in a few pieces of glass ware, one of which was a flask, as soon as bleach hit this flask (which previously had copper nitrate in it) the water went black!... I dont remember using it on my funnel, but I washed a funnel and wiped it dry before pouring the distilled water into the flask containing the silver nitrate... could this be the culprit? this morning the dirty solution had separated somewhat, there was a powder of the bottom of the second flask and the solution was more clear, but still dirty... I attempted to filter it but is just all mixed up again...

Should I just drop whats in there with copper and start again?

Looking for suggestions as to what to do with it now....

Thank you

 

[Palladium]

Silver recovered with copper won't be pure, and your results reflect that fact.
I had a policy of reserving the last removal of silver from my silver cell to be used in making the next batch of electrolyte. I operated my silver cell on a continual basis, until I'd parted all of the anodes I'd accumulated. There's method to my madness, which I'll explain.

If the silver used in making electrolyte yields anything more colorful than an almost colorless solution, especially after heating to a low boil, there's something present besides silver. By using the last silver recovered in the cell, I verified that I was depositing only silver, no copper, no palladium. My electrolyte, while still concentrated, after boiling, was just a hint of yellow, and became pretty much colorless when I added the required amount of distilled water. I always diluted the resulting solution, as allowed to cool, it grew immense silver chloride ( Nitrate ) crystals if not diluted.

The boiling process, in my experience, served to expel any traces of those nasty brown fumes, which, mixed with silver and copper, make a green solution. Also take note that when you have a green tint, you may also have platinum and/or palladium present, so test for each any time you have discoloration. If you process dental materials, it's almost impossible to avoid both of them, as silver becomes the carrier.

Harold

I to use the crystals from the last of the run for the next for the same reasons. It's a great way to quality control your silver if you don't have analytics. People ask me every now and then, " Well how do you know they are pure?" If you have run a silver cell before and know what your doing then you will know just from sight. I would say since the problem started when you diluted it that it could be iron. Your filtering through what looks like a coffee filter and if that's so the your never going to get it out because the particles are finer than the filter size. Try a Charmin plug in a soda bottle. Or you could let it settle and draw off the top for your solution for the cell. Take the last few milliters with the brown stuff that is left over and wash it into the container you plan on using to cement the cell solution in after your finished with your run. When you drop it the next time after washing when you melt it the iron will slag off and your problem will be gone.

 

[Palladium]

You said pure powder first. Then you said sterling recovered cement powder. I bet you made the solution up without melting the powder into shot first and then dissolving the shot didn't you? People think that by doing that it saves some time. And your thinking would be correct if it were gold powder, but I've found that with silver it ALL needs to be melted in order to save any problems or hassles. Melting it may have save you a lot of trouble verses dissolving just the powders. To melt is a very simple step compared to what you have had to go through just to get here. But hey!!!!! If you don't make mistakes then we don't learn. Refining is procedure, procedure, procedure !!!!!!!

Try the charmin plug or settling and let us know if that fixed it.

 

[Harold_V]

chloride ( Nitrate ) crystals if not diluted.

Thanks, Ralph. I have corrected the error (mine---a senior moment, I assume!)

Harold

 

[g_axelsson]

That brown color reminds me of silver oxide and the classical way of making silver oxide is mixing silver nitrate with a hydroxide. If you used bleach on your lab ware without cleaning it off you could have contaminated the distilled water with some hydroxide from the bleach. Bleach is caustic to keep it stable.

Göran

 

[Geo]

Baking your labware after washing is a good way of removing chlorides. I know heat has little effect on sodium hydroxide. If it was a bleach, heat will destroy it.

 

[RicXX]

It is true I didnt melt the powder first, lesson learned on that front...

I washed all my funnels, and unused glassware, by hand first then in my dishwasher with a high level heated dry... I dont know where any contaminates would have entered into my distilled, or could have entered as its right from the bottle... But it happened again when I added it to the half of silver nitrate that was left over from my first dilution... Same result, dirty brown sediment came out of solution... It has taken a few days but after letting both beakers settle and pouring them through 6 cross coffee filters with plug they are crystal clear and to the correct volume... Still dont know what the brown powder is, in the beaker it reacted almost like a very fine gold powder but didnt settle like it, too slow... The colour of the liquid lightened as well after the settling and filtering, its not nearly as deep a green as it was before, this could be due to the dilution or could it be the precipitate?

Nothing is a rush on this as I do not do this for a business, so I could afford the time to wait, and as such learned an important lesson... I have found that through the mistakes I have made and those others have made I have increased my knowledge and understanding.

I am very grateful to this forum and its members...

 

[Harold_V]

Still dont know what the brown powder is,

Hoke details a test for iron. It's been way too long for me to remember what it is, but the test is simple to perform---much the same as using stannous chloride.

If you had some of the original solution at your disposal, a drop could be tested for the presence of iron, which would have revealed if that was part of the contamination. I suspect it might be, considering you mentioned the now well filtered solution is lighter in color. It's obvious that what ever was removed was lending something towards the color.

Harold

 

[FrugalRefiner]

IRON
Iron in solution has sometimes a pale green color—the color of
copperas—but more frequently a brown, yellow, or rust color. The
rust color is so much like the color of dissolved gold or platinum,
that the worker may hesitate to throw away a brown solution be-
cause it looks so much like something of value. Here is a quick
test that reveals the presence of iron: dissolve a gram of ammonium
thiocyanate (potassium thiocyanate works the same way) in three
or four ounces of water; place one drop of your unknown solution
in a cavity of the porcelain spot-plate, and add one drop of ammo-
nium thiocyanate. If dissolved iron is present a deep blood-red
color will appear, usually at once, perhaps only after a few minutes’
exposure to the air.

This deep red color constitutes a very delicate test, as it will
appear when even a minute trace of iron is present. Indeed, if
you drop some thiocyanate on your hand, the chances are that
there will be enough iron on your skin, picked up from handling
iron and steel articles, to give a red stain. Do not make this test
in solutions containing much nitric acid, because the nitric acid
itself gives a red color with the thiocyanate. Mercury, oxalic acid,
and some other substances also interfere with this test. If copper is
present there may be a brown precipitate, which may or may not
obscure the red color produced by iron. A few acquaintance tests
made with solutions whose compositions are known will be helpful here.

Here is a second test for iron in solution: add a few drops of po-
tassium ferro cyanide, and if iron is present an intense blue color
will appear, either immediately or after exposure to the air.

Dave

 

[upcyclist]

Here is a second test for iron in solution: add a few drops of po-
tassium ferro cyanide, and if iron is present an intense blue color
will appear, either immediately or after exposure to the air.

And that Prussian Blue sure is purty

 

[RicXX]

Thank you for the tip and thank you for the text from the book, saved me a lot of time going back through it. On a down side I do not have any of the chemicals listed at my disposal (unless there is something I can find at a hardware store as a substitute) I refuse to have ammonia in my lab for obvious reasons (not even windex) and even so the test says it will show red if there is nitric present, which there will be so it will be inconclusive anyway.

I am now running the cell with the solution, but there is now something different happening... The silver is forming almost feather like and not crystal like... in 2 hours my new cell was almost full, its light but was filling up the cell fast so I turned off the power and wadded it all together and pulled it out... Its very grey looking, but also with shiney parts... Im running 1V @1.5A from my powersupply, this is my new bigger 3L cell, im almost thinking of going back to my 1L cell... Or just scrapping it all (dropping) and starting over, huge lesson learned here, shot everything before redissolving it!

 

[RicXX]

The recovered solids from the cell (not calling it silver at this point) look almost like steel wool my girl friend says and she is right, thats exactly how it looks and how it acted when I pulled it out...

On second thought I think I will keep this going, take suggestions and follow what I can... run this through this way as an experiment to see what the outcome is... all im using now is a little electricity...

Good idea or bad idea?

 

[Palladium]

With that voltage and amperage it shouldn't do that except for two things I can think of. The solution is not concentrated enough or your filter material is to tight a weave or stopped up, but if that the voltage should rise and show it. I'm betting low concentration. The darker color is copper showing up. Wash some of them crystals and then take a couple and dissolve in a white plastic spoon. If you see a green hint then its copper co percipating with silver.

 

[RicXX]

Palladium

The solution has more than 160g / L ... I dissolved approximately 500g into approx 1200 ml solution then diluted to 3000 ml in the cell...

Did the spoon test, no colour... (Photos to follow) Maybe the filter is a bit tight? Could the anode basket be packed to full?

 

[Palladium]

Hummmm. Scrap the solution and start fresh.