Processing SilverPlate With H2O Cell

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I read some hours about everything I could find that could be part of the explanation. And I got some ideas in my simple mind:

Cathode: nascent hydrogen
Anode: nascent oxygen oxidizes the silver/anodizing silver => Ag2O (brown) (maybe also hydroxo/oxo/aqua complexes, which I hardly understand)

Ag2O + 2 H nasc => 2 Ag + H20

The formed Ag is freshly reduced/cemented at typically light gray. Ag is more catalytic to make Hnasc molecular again than copper, - though I don't understand enough to decide if this matters in any way. Iron is even more catalytic to Hnasc than silver, so it would be interesting to see, if there is any difference between graphite and steel cathodes. If so, graphite should work better.

This theory could eventually be proven by altering plus down/minus up to minus down/plus up in a vertical electrode setup. The second one should work better: Minus (cathode) down would let the newly formed H nasc be led up to the anode with its newly formed brown Ag2O and reduce it to light gray silver.

Since silver also cements on the base metals in the anode, when the electricity is shut down, there must be some water soluble silver compound. Here I think some silver hydroxo/oxo/aqua complexes might play a major role.

Can anyone tell, if at least parts of this explanation sound plausible?
 
While I looked at this diagram: http://www.leifiphysik.de/sites/default/files/medien/elektrolyse01_energiespeich_gru.gif
I thought of this OH-, which wanders towards the anode. Maybe this is forming a complex water soluble compound with Ag2O? Fact is, there is no visible gas production at the anode. Fact is, when H2 bubbles happily at the cathode, there must be some OH- and they have to go towards the anode - what do they do there? - not forming oxygen gas at least. Okay, Ag2O....BUT what's going on with the H of OH-? I think I'll have to find some possible candidates in the books half educated me mostly do not understand... :) ...at least only half of it.
 
Ag2O forms Ag(OH)2- with water, which is slightly soluble. This might cement on the base metals or/and be reduced by Hnasc, - very much like reducing silver oxide with H2O2.

But concentrating on the most simple possibility, this should be an explanation: anodic oxidation of Ag to Ag2O, which dissolves and cements when the cell is off overnight, more dissolves and cements again.
 
One more wild guess: Other metals like Cu, Zn and Ni might be passivated by their oxides or at least their oxides might stay on the surface of the anode or build soluble comlexes,if they are amphoteric and soluble at pH8,5 (Zn).

Need to do more experiments...
 
Lets bust up a compound of water, forcing the water compound to split.
We will use an external force, a battery, and give a charge to a pair of electrodes, sitting in the jar of water.

We will bust up this water compound into it ionic form, pushing or pulling these ions apart into the Cations and Anions and separating them in this jar (cell).

We give charges to the electrodes, with our battery or power source, and with its external circuit the ability to move electrons, this battery having the ability to take electrons from the anode electrode (making it electron poor) and give electrons to the cathode (making it electron rich), thus giving these electrodes a charge, anode positively charged, and cathode negatively charged.
Anode positively charged (electron poor).
Cathode negatively charged (electron rich).

Here we will move electrons in this complete circuit, externally moving electrons through electrodes wire and battery (which is actually using a chemical reaction inside to move electrons chemically, or electro-chemically through it cells), and through our cell moving electrons electro-chemically as the ions are oxidized (gain of electron) and reduced (loss of electrons).

OK lest bust up some compound to ions, separating them into charged ions,
H2O we will split,
Into Positively charged Anions (H+) (missing electrons, and wanting some electrons to fill its atomic shell),
And negatively charged Cations (OH-) (with an excess of electrons willing to share some of its profit)

(H2O) split --> H+ + OH-

Now lets get busy and check out what is going on in our jar (cell)
Opposites attract like repels
The positively charged Cation (H+) being attracted towards the Negatively charged cathode electrode.
The negatively charged Anions (OH-) being attracted towards the positively charged anode.
OK things are beginning to get busy in there several things are beginning to happen at once, lots of oxidation and reduction going on, on both sides of this cell (elections moving in the external circuit), electrons being transferred all over the place, wow lets slow down and just look at portions of the cell at a time, too much commotion going on to keep up with everything going on at once.

Reaction at the positively anode, (an oxidation reaction is taking place) with the oxidation of water 2 H2O (l) --> O2 (g) + 4H+ (aq) +4e-
Electrode potential E0 (oxidation) = -1.23 volts

Water giving up electrons (oxidation) to the electron poor anode electrode of our cell, which of course our battery takes away, as these electrons travel through the wire (well we will not confuse ourselves more by looking at the reactions going on inside our battery (cells) power supply at this time), and giving those electrons to the cathode
At the anode + electrode, the anode wants electrons (the battery took his and made him electron poor, and since we spit this water and the Hydroxide (OH-) anions were attracted to the anode electrode.
The oxidation of water the anode is taking electrons from our water.
---------------------------------------

On the other side of the cell another reaction is taking place.
Here a reaction at the negatively charged electrode (rich in electrons), there is an reduction reaction going on (electrons being given), e- being given to the H+ Cations, to form the hydrogen gas, hydrogen being reduced (hydrogen Cations gaining electrons, from the electron rich cathode) to form atoms of hydrogen with a full shell of electrons, are happy to forms H2 gas and escape from or cell, (the half reaction balanced with acid), reduction at the cathode,
2H+ + 2e- --> H2 (g)
Electrode potential E0 (reduction) = 0.00 volts

Now lets balance with the acid/base reactions.
Anode oxidation'
4OH- (aq) --> O2 (g) + 2H2O (l) 4e-
Oxygen gas here is escaping our cell.

Cathode reduction,
2H2O (l) + 2e- --> H2 (g) + 2OH- (aq)

Combining these half reactions we get.
2H2O (l) --> 2H2 (g) + O2 (g)

So basically we used an externally forced electron movement to split water into its gases hydrogen and oxygen, now we just have to be careful these gases do not mix and want to make a big boom back into water; maybe if we carefully control that reaction we can make a torch.

now if we start using metal that will oxidize at the anode, and change our electrolyte (acidic or basic) we can begin to get more reactions going on in this cell, which sets up a whole lot more for us to consider, as these electrons are transferred in the electro-chemical reactions of our cell...

That sets up whole lot more goings on to discuss.
and as these react not only electro-chemically but also with acid and base reactions in the cell.
 
In the same setup I will find out, if

a zinc anode will be broken down, only oxidize or dissolve (visible to the eye, measuring the change of conductivity, pH, ORP)
a copper anode will be broken down, only oxidize or dissolve (visible to the eye, measuring the change of conductivity, pH, ORP)
there is any difference between using tap water and distilled water (tap water might contain useful electrolytes and/or buffers)
there is any change in pH after cementing overnight

I believe copper will only oxidize to non-soluble CuO and be passivated, zinc will dissolve since it is amphoteric and build Zn(OH)3- at pH8,5 of the running cell. My tap water was pH7,5 and went up to 8,5 after running the cell, probably also due to the reaction of Ag2O to Ag(OH)2-, so if all is cemented, the pH should go a little down again, though not down to 7,5. edit: maybe not, because while Ag leaves the solution, some other metal, probably zinc might dissolve.

I hope I have some spare time to check those questions today.

I think this could be the absolutely best treatment of especially the problem child silver plated german silver (Cu-Ni-Zn) with easy reusing and if necessary, easily regenerated electrolyte.
 
there is any change in pH after cementing overnight
Click to expand...

The pH was around 10 now!
clear filtrate gave a little AgCl with HCl (white precipitate/darkened violet in light)
This time it didn't cement, but I got only Ag2O (dissolves clear colourless in HNO3, pecipitates with chloride/with H2O2 the brown Ag2O reduced to light gray Ag)
No sign for copper/nickel contamination. I could not exclude zinc contamination, yet.
Thick black, in parts green-blue crusts on the anode flatware.

for more I hadn't the time, busy day
 
solar_plasma said:
there is any change in pH after cementing overnight
Click to expand...

The pH was around 10 now!
clear filtrate gave a little AgCl with HCl (white precipitate/darkened violet in light)
This time it didn't cement, but I got only Ag2O (dissolves clear colourless in HNO3, pecipitates with chloride/with H2O2 the brown Ag2O reduced to light gray Ag)
No sign for copper/nickel contamination. I could not exclude zinc contamination, yet.
Thick black, in parts green-blue crusts on the anode flatware.

for more I hadn't the time, busy day
Click to expand...


solar_plasma

Thank you for giving your time to research and find out for your self,that my cell does have great potential.Yes you are correct in your finding so far about the three types of silver and I assume that you haven't set aside a sample of the filtered solution,so you can find the fourth state of silver it produces(colloidal silver).To reclaim that you have to let it naturally evaporate and it will drop out on it's own.You really should try it with silverplated flatware on the anode and cathode.The cathode side will passivate it's self.


butcher

Please build your self a small scale cell,so that you can watch all the different cycles it goes through,it would help you to better explain it.You make great posts all the time,but it is my opinion that solar_plasma has a better grasp and understanding of my cell simply because he has seen what is hard for me too put into words.I mean NO disrespect to you or your intelligence,because believe it or not it is you who I always read on this forum no matter what.



modtheworld44
 
In the clear colorless liquid is some Ag(OH)2- dissolved and can be precipitated as chloride. This I can confirm. I am pretty sure, there also should be dissolved zinc, which I have to check. If there is any greater deal of colloidal silver it should react with HNO3 and can be tested by choride precipitation. I will check this, too.

I believe it should be avoided to let the pH go much higher than 10, because the copper and nickel oxides might form soluble hydrates, - in concentrated alkali hydroxides at least they probably do.

Yeah, Butcher you should really join those experiments, since you have a better understanding of electro chemistry than most of us and you know how to explain it in a way everybody can follow.
 
I believe the reason, why only the Ag2O is floating around while the copper and nickel oxides cling to the flatware is, that only Ag2O is a victim of an equilibrium reaction from solid to soluble and back again.

Ag2O + H2O <=> 2 AgOH

AgOH + OH- <=> Ag(OH)2-
 
modtheworld44,
I wish I had the time to build one of this type of cells, (life has gotten me very busy just trying to keep my head above water), I would like to build one, so I could ponder over what may be happening inside, I have built and run many different types of cells, and just love trying to figure out what is going on, many times it is just a guessing game, even using educated guesses, as during operation of many cells things can change during their operation, pH can play a big role, many time it changes during operation as hydrogen gas can easily leave the cell, hydrogen from acid or even the water involved , pH can also be slightly different on each side of the cell as the anion and cations are separated.

I have not been able to comment on this cell, as I have not had time to play with it, but I thought I might add a little to this discussion where I may be able to, maybe later when I get a more little free time I can build one and see what you guys are discussing.
 
No sign for copper/nickel contamination. I could not exclude zinc contamination, yet.
Click to expand...

I had reduced a bigger part of the Ag2O with H2O2 and did let it sit for a day in HCl. The solution above became slightly green, so some copper/nickel contaminants have been found, not much.

Edit: Later in another thread one of the moderators told, that H2O2 is no good way, too vigorous - danger! After my first melt I saw that the mud needs to get refined anyway, so better way is to dissolve and cement or dissolve and go one of the chloride routes. Another option is using an oxidizing flux and melt directly, but I don't know the resulting purity and how much loss it will cause. But I tried and it works, too.
 
It has been asked, if the amperage will sink. It sinks only until all chloride is precipitated. Thereafter, it is pretty constant. So the amperage cannot be used as an indication for when then process is finished similarly to the sulfuric gold stripping cell. This observation is plausible since this cell works by anodizing, which is an oxidizing of the anode surface and not a transport of metal cations from anode to cathode (acidic) or from cathode to anode (base).

The firstly exposed Cu-Ni-Zn areas get copper plated. Later they become black. You can clearly see, where silver is not stripped yet, - those areas are still light in color, white, gray or silver.
 
If anyone wants to help and participate in this journey, you could help me to find the unanswered questions in this thread and re-post them. This thread has grown big and I believe I understand most of the mechanics of this process, now. It would also help to plan the next experiments.
 
I feel the need to make clear, this process is not producing colloidal silver, but Ag2O. Using tab water, DC and impure anodes are the three things they avoid, when they want to make colloidal silver as you can see in the video link on one of the first pages.

Thank you once again, modtheworld44!! This IS the AP equivalent to recovery of silver from silver plate! It is cheap, reusable, minimizing waste and pretty safe.
 
The question has been raised, how to speed up the process. Since voltage has not to be hold down to gain highest purity, you can just use 24V. Probably you could use more to get a higher amperage, but I would not advise this, since up to 25V are not harmful. You don't want to cling at high DC till you're dead or act as the electrolyte and poison yourself from the inside.
 
I stripped a silver plated dinner tray about 60cm x 40cm, which once has had 180g silver according to the hallmarks. The powder is still a little wet after several days of drying, but it is weighing 130g now. 1/4 is still untouched, because a hydrogen bubble had built up under the electrolysis. This was done in a relatively short time, some hours not more.

When I bought the tray, it was in a bad condition, worn, dented, scratched and randomly oxidized. So, I was glad to find this method to strip it, without needing to cut it into a smaller pieces. It seems, when I am done with the stripping, it can be cleaned, polished and used again, maybe even get a new silver plating. For now, I am glad I could get the silver without destroying this nice tray, which might be 50-60 years old.
 
update: stripping the last silver from the tray the amperage actually is going down and of course the stripping slows down
edit: after clean the tray, the amperage goes up again / partly also silver foils loosen from the tray / there are red spots, that look like copper plated / blue solid particles are formed here and there / looks like a lot of different side reactions are going on
 
According to my text research a pH of about 10, like I got with my tap water under electrolysis is quite interesting, because all possibly involved oxides and hydroxides of copper, nickel and zinc have a solubility beneath 10mg/L:

Abb.2.3 http://www.lanuv.nrw.de/wasser/abwasser/forschung/pdf/Abschlussberichtschwermetallabwasser.pdf

But also Ag2O and AgOH reaches its lowest solubility at pH10 and above, 0,0001 mol/l, maybe 20mg/l:

http://www.researchgate.net/post/At_what_pH_does_silver_hydroxide_formation_take_place

I have collected about 200g sludge now (estimated dry weight).

The composition of the filter sludge becomes more and more interesting. I know (more or less), how to make a classic quantitative analysis of the cations, but if anyone has some good ideas, how this could be done with the least effort in this special case, please let me know. Thereafter, I would like to find out, how much of the sludge is elemental silver and how much is oxygen and hydrogen. Since all oxygen is consumed at the cathode, it has to go somewhere. Heating would decompose those silver chalcogenides, so I could weigh it before and after and collect the gasses for further examination. Any ideas are welcome.

The filtrate is absolutely water clear. I would like to know, what is left in it, when all silver traces are precipitated by adding HCl to neutral. Probably not much that hasn't been in it before. Maybe I could compare the conductivity with tap water to find out.

edit: page 6 and 7 seem to give a quite good explanation and some answers http://www.dtic.mil/dtic/tr/fulltext/u2/478632.pdf

Under alkali condition I see some parallels to the silver oxide battery, only we are both charging and discharging the "battery" in his setup. I have come to believe, that colloidal silver only can form in very pure distilled water. In most tap waters NaCl will be one of the major electrolytes, which is responsible for the high pH in this setup.
 

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