Author Topic: too much sodium carbonate?  (Read 918 times)

Offline rogwhat53

  • Participant
  • **
  • Posts: 52
  • Likes: 2
too much sodium carbonate?
« on: April 16, 2020, 05:09:30 PM »
I am using Kephra's Na2CO3 + Karo Reducer + 140degF with maple leaf anode and 5mA@>10V to currently produce both 20ppm and 40ppm, both uncapped and capped with Knox Gelatin.

I had previously used the same generator with no electrolyte and monitored the current rise, integrating the correct mA-hrs until current limit was reached and so had no problem with Faraday count of total mg of silver. But finally I realized that if I used Kephra's electrolyte I could largely eliminate the plating out of silver on the cathode.... that is such a neat trick! And realizing it is not 100%, but a compromise, I tended towards "rounding-up" to a little more rather than less.

But about the same time, a few weeks ago, I began noticing that sometimes, more often with 40ppm, I would get a cloudy precipitate off the anode in the second hour (2 hrs at 5mA).

I have enclosed a jpeg of my homemade generator. It is presently brewing a pint-batch to test this suspicion of too much Na2CO3 in there, and shows 5mA @ 12V. You can see two quart bottles of capped 40ppm Colloidal Silver behind the generator, one clear and yellow but the other cloudy as described, both made with 0ppm DW tested on twp TDS meters.

Can excessive Na2CO3 be the culprit here?

rogerw

Offline rogwhat53

  • Participant
  • **
  • Posts: 52
  • Likes: 2
Re: too much sodium carbonate?
« Reply #1 on: April 16, 2020, 05:53:09 PM »
OK, in this enclosed jpeg you can see a new mason jar sitting on top of the original cloudy colloidal silver..... and it is cloudy too. I used half of the Na2CO3 in it as previously..... And earlier today I had tried using more Karo reducer, but still a precipitate form on my anode which is very fine and light in color and it only forms in the second hour of a 40ppm run..... the first 20ppm remains clear. Then, as I remove the electrodes the precipitate easily wahes off into the colloidal silver and clouding it.

I am putting both electrolyte and reducer in at the beginning of electrolysis..... any hints as to what I am doing wrong?

rogerw

Offline cfnisbet

  • Administrator
  • Participant
  • *****
  • Posts: 2013
  • Likes: 115
Re: too much sodium carbonate?
« Reply #2 on: April 16, 2020, 09:04:35 PM »
I don't think it is too much electrolyte, I think it may be the Karo.

I would try a different capping/reducing agent. I have had better results with maltodextrin.

Offline Gene

  • Expert
  • Participant
  • ***
  • Posts: 1155
  • Likes: 84
Re: too much sodium carbonate?
« Reply #3 on: April 17, 2020, 12:27:21 AM »
Of all the reducers I've used, by far, Maltodextrin provides the clearest, least "tyndal" Colloidal Silver I've ever made. I use it when I'm making 80-120PPM "naked" but I still use Karo for making gel capped.

Offline rogwhat53

  • Participant
  • **
  • Posts: 52
  • Likes: 2
Re: too much sodium carbonate?
« Reply #4 on: April 17, 2020, 01:22:03 AM »
Thank you Gene and cfnisbet. I have an experiment in mind to try as a result of your comments. I do not have any maltodextrin, but I am going to wait till the 30 or 35ppm point to add the Karo solution and/or use less.

rogerw

Offline Gene

  • Expert
  • Participant
  • ***
  • Posts: 1155
  • Likes: 84
Re: too much sodium carbonate?
« Reply #5 on: April 17, 2020, 02:57:53 AM »
If you're not running at a much higher temperature than room temp (which is 75F and not colder) the most silver oxide you can accumulate in the cell water before it starts precipitating out is 21-22PPM. If you go over this, anything above this will NOT reduce and me? I wouldn't drink that.

If you're running at 150F, you can push it to about 40PPM.

The best way (but it requires running at the higher temp) is to add enough reducer to reduce whatever PPM you plan on making (plus a little extra for insurance - more doesn't hurt anything) and just run the cell up to however long you need to, to reach that PPM.

Where the solubility limit of ionic silver in water is as I stated above, this does NOT apply to reduced colloidal silver because its NOT dissolved anything. Its nanoscopic elemental particles of silver FLOATING in water. A colloid is a suspension, not a solution. So, as long as you keep reduction happening faster than production of silver oxide to keep the total dissolved silver oxide below the stated limits, you can go all the way up to at least 320PPM though here, people usually run just below boiling since it takes so long to do so they're running a high enough current they're producing more silver oxide they need to get dissolved quickly AND reduced quickly.

I routinely run to 120-160PPM at the 150F temp and my Colloidal Silver comes out plenty good enough.

You can buy maltodextrin as Carbogain but they rape you for it.  If you can find a home beer/wine brewing supply shop (there's usually one in every major city), they should have it and it'll be cheap. I bought a pound this way and I think it cost me all of about $3.  For me, thats damn near a lifetime supply.

Start with 20-40PPM and ace this before starting to 'speriment.


Offline rogwhat53

  • Participant
  • **
  • Posts: 52
  • Likes: 2
Re: too much sodium carbonate?
« Reply #6 on: April 19, 2020, 10:59:48 PM »
Well I tried varying both the electrolyte and the karo reducer, but what worked was lowering the temperature to 120degF to 130degF. I am adding the reducer (12 drops of 50%Karo for 40ppm) at the start of electrolysis as before In between those temps it makes a beautiful clear yellow and remains yellow all the way to 40ppm.

At 150degF to 160degF it starts out more yellow-orangish and in the second hour (5mA x 4mg/mA-hr = 2 hrs for 40ppm in a Liter) it would start to form that cloudy precipitate.... the result was a cloudy but pretty yellow-peach color. It seems to me that the higher temp must influence a somewhat larger average silver NP being more yellow-orange.

I do not know what that precipitate at 150degF to 160degF is but I agree with cfnisbet, it is likely not the Na2CO3 electrolyte but likely the karo at the higher temperature.

I do understand the solid solubility limit of Ag20 versus temperature, as Gene states. I will also warn that unless you are stirring well it is the region close to the anode which matters and if the ionized Ag20 does not migrate fast enough away to the rest of the water, it can hit the solubility limit in that limited region and begin precipitating before it carries into the larger total water. If you calculate ppm on the total water, you could get fooled then as to when precipitaion might start.

I had not seen anyone else having trouble with Karo at 150degF to 160degF though..... maybe I missed this somewhere....

Bottom line though is that at 120degF to 130degF I am getting beautiful 40ppm results.

thanks, all.

rogerw

Offline rogwhat53

  • Participant
  • **
  • Posts: 52
  • Likes: 2
Re: too much sodium carbonate?
« Reply #7 on: April 21, 2020, 11:15:54 PM »
a postscript to my last reply:

I suppose the >10Vdc cell voltage and the stated motivation to better "scavenge" the Ag2O from the anode might well mitigate my above claim about stirring or thermal currents helping to diffuse the Ag2O into the larger volume of water and away from the smaller space in which the Ag2O is dissolved (or precipitated).

I am not doubting that this >10Vdc scavenging effect is true, I think I have observed the effect, but I will admit that I do not understand why it should be true....Because, adjusting the cell voltage by adjusting the depth of a thinwire cathode is merely creating a resistance between the thinwire, with its attendant low contact area, and the water/electrolyte. Thus the increased cell voltage (and thus the increased electric field) occurs only along the thin "contact resistance" region between the thinwire and the electrolyte but not in the vicinity of the anode where the electromigration rate would be critical.

Am I wrong on this? I am imagining a contact potential of silver anode to electrolyte and another of copper cathode to electrolyte, both of which are constant voltages if a current flows....  I think Kephra said these sum to something like 3.3V (IIRC) and are determined by electrochemical properties?  Then if the thinwire copper cathode contact area is adjusted, an additional voltage drop occurs across THAT contact resistance but not across the electrolyte between the electrodes???

rogerw

Offline wgpeters

  • Kephra's other account
  • Expert
  • Participant
  • ***
  • Posts: 634
  • Likes: 75
    • SilverTron Support
Re: too much sodium carbonate?
« Reply #8 on: April 22, 2020, 02:38:42 AM »
Quote
Am I wrong on this?
Yes, you are wrong.  The electric field exists between both electrodes, not between just one electrode and the water. 
A person's worth is solely determined by what he does for others.

Offline rogwhat53

  • Participant
  • **
  • Posts: 52
  • Likes: 2
Re: too much sodium carbonate?
« Reply #9 on: April 22, 2020, 05:06:50 PM »
Quote
Am I wrong on this?
Yes, you are wrong.  The electric field exists between both electrodes, not between just one electrode and the water.

Thank you for your reply. I am just trying to understand something I have seen experimental evidence of, but obviously do not understand why. It seems that I often find myself in the position of knowing that, "I do not understand everything I know."

Yes, of course there is an electric field between the electrodes. If the two electrodes have a contact potential of 3.3Vdc (IIRC), then the effective resistance of the electrolyte between the electrode multiplied times the current must be an extra voltage drop in series with those two contact potentials.

Thus the electric field in the electrolyte would be the voltage drop per unit distance along this effective resistance of the electrolyte. (I realize that, for simplicity, I am reducing a 3 dimensional current flow and electric field to a simple 1 dimensional resistor, but perhaps this is not an erroneous simplification for this purpose.)

Thus the equivalent circuit I am imagining has these series components:  an ohmic contact resistance at the anode to electrolyte, a contact potential at the anode to electrolyte, an effective resistance in the electrolyte to the vicinity of the cathode, a contact potential from electrolyte to the cathode, and an ohmic contact resistance at the cathode to electrolyte.

It has been explained to me by others that the motivation for a thinwire cathode is the limited surface area per length, thus more easily adjustable ohmic contact resistance to the electrolyte. That made sense as far as it goes....

If this equivalent circuit assumption is correct, an adjustment in the series ohmic contact resistance at the cathode will not appreciably change the existing electric field in the bulk of the electrolyte between the electrodes (and assuming constant current), or, if so, how? Seems as if it only changes the voltage drop across the cathode's ohnic contact resistance. So, what is wrong with this picture?

Again, I appreciate your reply but perhaps you can see I am hungry to understand more than has been explained (AFAIK) so far.

rogerw



Offline wgpeters

  • Kephra's other account
  • Expert
  • Participant
  • ***
  • Posts: 634
  • Likes: 75
    • SilverTron Support
Re: too much sodium carbonate?
« Reply #10 on: April 22, 2020, 05:22:44 PM »
There is no ohmic resistance at the boundary between electrode and electrolyte.  At the anode, the voltage across the boundary layer is .8 volts regardless of the current.  At the cathode, the voltage across the boundary layer is 2.72 volts regardless of the current through the cell provided of course the cell voltage is high enough.  The only ohmic resistance is through the electrolyte.  The electric field strength is solely determined by the voltage across the electrodes.  This field strength moves negative oh ions toward the anode, and positive ions toward the cathode out of the boundary layers.
A person's worth is solely determined by what he does for others.

Offline rogwhat53

  • Participant
  • **
  • Posts: 52
  • Likes: 2
Re: too much sodium carbonate?
« Reply #11 on: April 22, 2020, 06:22:17 PM »
Ah!  Now I get it..... and my equivalent circuit is basically wrong. Essentially the electrolyte is a 3D current and field that is altered by the thinwire contact area adjustment.

And in the model you present, the way the thinwire adjustment raises the field, or voltage gradient, is by forcing the current in the electrolyte into a smaller and smaller space/volume of electrolyte as it approaches the cathode, I suppose.Thus the voltage drop, is not linear with the distance between the electrodes and is increasingly larger nearer the cathode, but inevitably also some appreciable effect near the anode.

btw, in my understanding and experience, there is ALWAYS a contact resistance between dissimilar conductors but it can certainly be negligible to a calculation, and your claim makes good sense to me in this light.

I shoulda thought of this! (Doh!)

Thank you, sir, for your reply.

rogerw
« Last Edit: April 22, 2020, 06:50:57 PM by rogwhat53 »

Offline RedDogJT

  • Participant
  • **
  • Posts: 198
  • Likes: 8
  • Information junkie & autodidact
Re: too much sodium carbonate?
« Reply #12 on: April 22, 2020, 09:17:43 PM »
I really love the retro look of your custom power supply.  Not since the days of Flash Gordon (I'm dating myself) did you see such cool dials!
Only thing that would make it better is one of these coils!
Nothing is as it seems and nothing is at it appears

Offline rogwhat53

  • Participant
  • **
  • Posts: 52
  • Likes: 2
Re: too much sodium carbonate?
« Reply #13 on: April 22, 2020, 10:05:38 PM »
yeah, RedDogJT, I was actually known as the "Analog Dog" in my old mixed-signal CMOS IC design group.

I like analog gauges where precision is not an issue. I am kinda retro too I guess. Enclosed is a picture of my lab bench at home, :-)

rogerw

ps - btw those meters on top are VTVMs (vacuum tube voltmeters)  largely from the late 1940s and 1950s in terms of state of the art design.......

And where is Tesla when we need him?
« Last Edit: April 22, 2020, 10:12:19 PM by rogwhat53 »

Offline RedDogJT

  • Participant
  • **
  • Posts: 198
  • Likes: 8
  • Information junkie & autodidact
Re: too much sodium carbonate?
« Reply #14 on: April 22, 2020, 10:24:15 PM »
Very cool. Thanks for sharing.  8) ;)
Nothing is as it seems and nothing is at it appears