Sciencemadness Discussion Board - Porous Pot for Voltaic Cell

Porous Pot for Voltaic Cell

gravityzero - 13-10-2017 at 10:04

Would like to start looking into electrolysis cells a bit further.
Found a patent example that calls for a porous pot basically 65mm x 190mm
Examples have been given using a terra cotta flower pot as a suitable vessel.
Attempting to keep the diagram as true to form as possible is causing some issues.

Other than actually making the vessel, nothing within the dimensions, purchasable, has been found.
The closest item found is 50mm x 150mm, which is fairly far off.
Any ideas on how or where to get such an item is much appreciated.
Thanks to all in advance.

CRUSTY - 16-10-2017 at 05:05

Do you mean 190 mm wide or tall?

Melgar - 16-10-2017 at 22:29

Crush up all the terracotta. You don't need it anyway.

Crush it to powder then mix it with water. Mix it until it forms a workable clay.

Mold it into the shape you want. Make 3-4 in case something bad happens.

Let it dry. Like, completely.

Fire it. Kids have done it for school projects, so how hard could it be? http://www.homeschooling-ideas.com/smoke-firing.html

unionised - 18-10-2017 at 13:25

Quote: Originally posted by Melgar

Crush up all the terracotta. You don't need it anyway.

Crush it to powder then mix it with water. Mix it until it forms a workable clay.

I rather doubt that will work. The terra has already been cotta

Chemical changes take place during the first firing, so a second firing won't work properly.

gravityzero - 18-10-2017 at 13:50

Thanks for all the suggestions. It is appreciated. The width is 65mm x height of 190mm.
I agree with Melgar, except I would just use terra cotta clay that is new, not previously fired.
It appears that this can be done easier than originally thought.

New clay would be shaped, dried, then fired.

Sulaiman - 18-10-2017 at 14:34

For my very disappointing experiments in electrochemical voltaic cells I used two of these pots
http://www.edulab.com/prod/daniel-cell-porous-pot-150x50mm
which, judging by dimensions alone, are probably similar to the pots that you originally mentioned.
They are MUCH more porous than a teracotta flower pot.

Although it is best to follow a working example as closely as you can,
in this case just a few considerations will allow scaling with no detrimental effects;
- scale currents in proportion to areas of electrodes to achieve constant current density (A.m^-2),
which is, I believe, what has a great effect on the electrochemistry at the electrodes
- maintain molar concentrations of electrolytes (overall cell e.m.f.) rather than quantities/portions/weights etc.

Melgar - 28-10-2017 at 04:38

Quote: Originally posted by unionised

I rather doubt that will work. The terra has already been cotta

Chemical changes take place during the first firing, so a second firing won't work properly.

It was my impression that firing clay bound the particles together via partial vitrification, which is more of a physical rather than chemical process, and could be repeated. Oh shit, never mind. Forget I said anything. Last thing I want is to get into another argument with you about glass chemistry. (In the real world, there's no such thing as vitrification, right?)

The reason so many experiments are done using porous unglazed pots, is because of how widely-available those were during the 19th century, when much of the initial experimentation was done, regarding electrochemistry. They did not have the variety of inert materials that we have today, especially plastics. PETE plastic is quite inert to decomposition, and conveniently, is also the polymer that's used to make polyester fabric. So if you had some thick polyester fabric, and perhaps access to a sewing machine to make it the correct shape, this would allow you to make a superior divided cell to those terra cotta pots.

unionised - 28-10-2017 at 12:04

Quote: Originally posted by Melgar

Your impression was mistaken.
It's a dehydration reaction, then a vitrification.
The dehydration isn't reversible on any sensible timescale.
You could get into fewer arguments with me and others by not posting stuff that's plainly wrong.
As you say, "The first step in the process of learning something is admitting that you don't know it already."

[Edited on 28-10-17 by unionised]

Sedit - 28-10-2017 at 22:12

I always just used a regular old flower pot with the hole plugged up. Sometimes you can find them without a hole which is even better. Standard use calls to place a material that has the same Ion you wish to use in it as an electron transfer, you run the voltage backwards and it causes the Ions to get trapped inside of the clay pot. You can then run take it out, wash it off and put in your working chemicals and it acts like a solid barrier to the chemical you did not want to come through.

What Meglar said BTW has 0 chance of working. Fired Clay is an Aluminum Silicate, you cant reverse the process. Before hand Aluminum Oxides work with Silica to form the fun sticky mess you know of as clay through hydrogen bonding but after firing its a totally different chemical.

Quote:

So if you had some thick polyester fabric, and perhaps access to a sewing machine to make it the correct shape, this would allow you to make a superior divided cell to those terra cotta pots.

Sorry this is just not true either, it would be very hard to get the fabric to produce pore sizes on the scale that you will get using fired clay, Fired clay is great, its basically porous glass, what could really be better?

[Edited on 29-10-2017 by Sedit]

Melgar - 29-10-2017 at 00:08

For the record, I'm not actually that invested in whether crushing up a terracotta pot could make it so you could mold and fire it again. I still think you could sort of do it, based on my understanding of ceramics, since there would be SOME partial melting where the vitrified parts touched each other, but the results would probably be crap. I don't remember why I actually suggested doing that in the first place, but I meant it in the same way that I might put "1) Smack yourself in the face for being that careless with nitric acid" as a step in a process. Trying to amuse myself while giving advice, I suppose. The real point I was trying to make was that it's not that hard to fire clay yourself, even without a kiln.

Quote:

However I am somewhat invested in the idea that thick polyester cloth could make a suitable divider for a divided cell. Porous clay is really not that great. Salt moves around in it via capillary action and clogs up those pores very easily if it dries out at all. Often, it will clog up those pores even if it stays immersed, due to the higher resistance and greater heat generated within the ceramic. This heat will drive out the water, and leave behind the salt. And once the pores are clogged up with salt, it can be next to impossible to unclog them. Additionally, how do you come to the conclusion that the pore size in porous ceramic is ideal? Because so many people on these boards have had nothing but success with them? Of course not; everyone is trying to find superior alternatives because of how much grief clay pots have caused them. The resistance is almost always too high, and they run into the problem with heat driving out the water and leaving salt, if they turn up the voltage to compensate. Now, if you look at every single divided cell that's in use in the modern world, they're either made of paper (cheap), fritted glass (long life), or a porous polymer (compromise between the other two). Really, the divider just has to provide enough of a physical barrier to prevent too many ions from going back and forth between the electrodes, getting subsequently oxidized and then reduced. (edit: or in the case organics and some inorganics, being irreversibly oxidized or reduced) If a small fraction cross over though, and get on the wrong side, it's not typically a huge problem. The bigger problem is likely to come from a resistance that's much too high. Also, clay is more like a zeolite full of miscellaneous ions, than it is like glass. Now, if you don't mind random iron, aluminum, magnesium, calcium, sulfate, silicate, etc. ions getting into your solution and doing whatever they're prone to do, then have at it. Maybe they were necessary for the reaction that OP is trying to replicate? However, for a general-purpose cell divider, a terracotta pot is far from ideal.

[Edited on 10/29/17 by Melgar]

unionised - 29-10-2017 at 02:26

Quote: Originally posted by Sedit

Quote:

So if you had some thick polyester fabric, and perhaps access to a sewing machine to make it the correct shape, this would allow you to make a superior divided cell to those terra cotta pots.

OK, on this one, I agree with Melgar.
You can use cloth, and they do (albeit asbestos cloth was traditionally used in this case).
It seems you can get asbestos free versions; it's not clear if this stuff is asbestos or not, but it's a cloth diaphragm for electrolytic cells.
https://www.alibaba.com/product-detail/Non-Asbestos-Diaphrag...

Sulaiman - 29-10-2017 at 04:18

If you are experienced in electrochemistry (I am not) then choosing and using a membrane is a complex subject,
there are membranes far superior to a porous pot,
but I think that it is best to start with something which even though not perfect, it is predictable, and it produces results similar to those published,
then go on to look for the ultimate membrane once you have an appreciation of the subject.
I just want to experience and understand the principles involved, for which porous pots work just fine,
if I wanted an efficient commercial cell - - I'd buy one made commercially

The pots that I used are I guess as good as were used by the pioneers, and all of the problems experienced in the early voltaic cells can be investigated.
I have not yet tried these pots with electricity going in, only out, as primary voltaic cells,
so I do not know how they would perform in electrolysis cells for example,,
but the pots are inert, durable and cleanable (mostly), so they are very re-usable.

When starting a new topic of experimentation I like to minimise the number of ways that I can fail (I'm expert at failing !)
and as the membrane is a critical part of an electrochemical cell,
it is best for me to start with a known good performer.

For high current electrochemical cells I would expect the resistance of the electrolyte filled pores to be significant but not insurmountable.

In summary: I recommend porous pots for initial electrochemistry experimentation and learning,
(unless someone can point to a tried and tested, foolproof (especially in my case), reliable, available, cheap, general purpose membrane)

bobdring - 29-10-2017 at 15:00

Have you seen the porous pots on Haines educational?

https://www.haines.com.au/

They have two listed but the largest is
Porous pot, 150 x 50mm L x D
Item Code : GE364501
Price
$3.00 (excl. GST)
$3.30 (incl. GST)

macckone - 29-10-2017 at 18:51

polypropylene 5 micron hepa vacuum cleaner bags.

https://www.homedepot.com/p/Cen-Tec-Replacement-HEPA-Vacuum-...

You can get these things at just about any store that sells vacuum cleaners.
I would assume the same is true in other countries.

Melgar - 30-10-2017 at 01:08

Quote: Originally posted by unionised

OK, on this one, I agree with Melgar.

Wow. I certainly wasn't expecting that.

Hug?

Err.. maybe later.

Reading more on the subject, I'm seeing that it's beneficial for the membrane to have ion exchange capabilities. This provides a sort of buffer layer of neutral ions between the two sides, so that when an ion enters one side, it quickly bumps a stationary ion off of its site, which then takes its place carrying the charge. With glass or fiberglass, these ions are typically sodium, calcium, silicate, and carbonate, possibly others. Clay has plenty of its own ions, which vary depending on the clay. With polymers, you need the surface to be somewhat polar, because otherwise it'd repel water and ions, and typically the treatment that makes the surface polar consists of partially oxidizing it. To provide ions for ion exchange, paper and polymer membranes are often impregnated with a salt, chosen for having relatively inert ions. Potassium sulfate, for example. This step would probably be unnecessary, though, if you only cared about what was going on in one of the two half-cells.

Sulaiman - 30-10-2017 at 10:24

Quote: Originally posted by macckone

polypropylene 5 micron hepa vacuum cleaner bags.

https://www.homedepot.com/p/Cen-Tec-Replacement-HEPA-Vacuum-...

You can get these things at just about any store that sells vacuum cleaners.
I would assume the same is true in other countries.

Have you actually tried this material ?
Does water wet it (do the pores fil with electrolyte) ?

unionised - 30-10-2017 at 10:34

Quote: Originally posted by Sulaiman

Quote: Originally posted by macckone

Have you actually tried this material ?
Does water wet it (do the pores fil with electrolyte) ?

The usual cheat for that is to soak it in alcohol or acetone, then rinse out the solvent with water.

Melgar - 30-10-2017 at 10:48

BTW, apparently the ultimate membrane for divided cells is made of this stuff:

http://www.fuelcellsetc.com/store/N117

Nafion 117. Basically, ion-exchaging teflon with triflic acid exchange sites. If you were a positively charged ion trying to get through a membrane, this stuff is like the SNES game "Ghosts and Goblins".

Corrosive Joeseph - 30-10-2017 at 17:33

Quote: Originally posted by macckone

polypropylene 5 micron hepa vacuum cleaner bags.

https://www.homedepot.com/p/Cen-Tec-Replacement-HEPA-Vacuum-...

If this works it is absolute genius

/CJ

macckone - 30-10-2017 at 17:56

The polypropylene bags need to be rinsed with alcohol to get a
good wetting which may or may not interfere with a particular
reaction. Other surfactants can be used. For making sodium
hydroxide it is a fair material. It is definitely better than the
clay pot method. I have also used agar which breaks down if
the hydroxide gets too concentrated. Diaphragm cells are less
effective than membrane cells. Clay pots are actually a diaphragm
cell. Membrane cells are only permeable to certain ions like sodium,
hydrogen, sulfate or chloride depending on the material.

Mesa - 6-11-2017 at 05:10

Quote: Originally posted by bobdring

Have you seen the porous pots on Haines educational?

https://www.haines.com.au/

They have two listed but the largest is
Porous pot, 150 x 50mm L x D
Item Code : GE364501
Price
$3.00 (excl. GST)
$3.30 (incl. GST)

You ever tried ordering anything from haines? They don't sell to the public.

EDIT: @OP You've gotten worried about a pretty meaningless detail tbh.

The specific physical dimensions of the pot are superfluous. The only details relevant to you is volume and surface area at the interface.

Get a pot that holds roughly the same amount of liquid, and has roughly the same wet surface area when submerged. The rest is irrelevant.

[Edited on 6-11-2017 by Mesa]

bobdring - 19-11-2017 at 08:04

I bought a few of the porous pots from Haines without any problems. They only supply chemicals to government/businesses however.

JJay - 11-7-2018 at 10:15

I remember doing lots of electrochemical reactions in chemistry classes, but I don't remember ever using a porous pot. I do remember using salt bridges. It seems to me as though a salt bridge would provide much more reliable performance than a porous pot. Is there any reason a salt bridge can't be substituted for a porous pot? Is there any advantage to using a porous pot instead of a salt bridge?

Melgar - 19-7-2018 at 21:10

Quote: Originally posted by JJay

I remember doing lots of electrochemical reactions in chemistry classes, but I don't remember ever using a porous pot. I do remember using salt bridges. It seems to me as though a salt bridge would provide much more reliable performance than a porous pot. Is there any reason a salt bridge can't be substituted for a porous pot? Is there any advantage to using a porous pot instead of a salt bridge?

Clay pots can transmit current through a much larger area. Salt bridges only make sense when you have no interest in scaling up, I guess. Also, consider how alkaline batteries are shaped. The goal of the design is clearly to maximize the interface area between the two half-cells.

Anyway, clay pots are supposedly a decent off-the-shelf approximation of how cell dividers are shaped when the goal is to maximize current.

JJay - 19-7-2018 at 21:39

Hmm... if I'm reading this right, just looking at this chart, assuming that sodium sulfate is the electrolyte in the salt bridge, that it has a 1 cm^2 cross-section and is 10 cm long, the resistance would be an additional 3 ohms at high temperatures: https://pubs.acs.org/doi/abs/10.1021/i460002a019

My power supply only goes up to 3 amps but will do 15 volts, so I think I'm perfectly ok using something like a 1 inch PVC hose filled with agar and sodium sulfate.

I have no idea what the resistance of a porous pot would be.

There are issues with scaling, but the same scaling issues that affect salt bridges affect porous pots (the volume of the pot follows a cubic law and the surface area follows a square law); if there is a problem with scaling the size of the cell, you can scale up by simply using more cells.

Melgar - 19-7-2018 at 22:34

Well, if you make a supported cloth dividing membrane in the shape of a clay pot, and then impregnate it with the same medium in your salt bridge, current would be a lot higher.

It's been my experience that salt bridges are only used when the main constraint is a lack of custom-made equipment. Also, because it makes the mechanism more obvious to students.

JJay - 19-7-2018 at 22:50

Quote: Originally posted by Melgar

Well, if you make a supported cloth dividing membrane in the shape of a clay pot, and then impregnate it with the same medium in your salt bridge, current would be a lot higher.

It depends really. There's a problem in that a piece of cloth might let too much mixing occur. I'm pretty sure that most porous pots won't permit nearly as much liquid-liquid contact as a piece of cloth, but that means that resistance is higher with a porous pot than a piece of cloth.

Quote:

It's been my experience that salt bridges are only used when the main constraint is a lack of custom-made equipment. Also, because it makes the mechanism more obvious to students.

What is your experience? You do realize that you can buy porous pots as pre-made components from educational suppliers, right? They're less messy to set up than salt bridges, and the mechanism is really in no way easier to understand with salt bridges than porous pots.

I think salt bridges lead to results that are more easily reproduced.

Sulaiman - 19-7-2018 at 23:54

3 Ohms passing a current of 3 Amperes will have 9 Volts across it,
9 V x 3 A = 27 Watts of heating inside a thermally insulating tube = molten agar

JJay - 20-7-2018 at 00:05

Quote: Originally posted by Sulaiman

3 Ohms passing a current of 3 Amperes will have 9 Volts across it,
9 V x 3 A = 27 Watts of heating inside a thermally insulating tube = molten agar

Right, but 1 inch = 2.54 cm, and one square inch = 5.08 cm^2.

That works out to 1.77 volts or 5.31 watts, and of course, the cell I'm planning will have cooling.

edit: The power loss across the salt bridge will actually be slightly more than 5.31 watts since the cross section of 1 inch PVC isn't a square inch; it's a half inch squared times pi, but close enough....

[Edited on 20-7-2018 by JJay]

Measurement of resistance of porous pots

Sulaiman - 20-7-2018 at 03:05

I just did a few quick mesurements using the porous pots that I mentioned above,
Vessel: c9.5cm diameter polypropylene tub
Cathode: copper sheet, 24cm wide with c14cm immersed = 336 cm² active area
Anode: 3.5cm dia. copper pipe with c13cm immersed = 143 cm²
Electrolyte: Tap water, 1M H₂SO₄ or 1M CuSO₄

1) Water no Pot 10V, 0.4A = 25 Ohms .. (initially very high resistance dropped within seconds to this value)
2) Water & Pot 10V, 0.5A = 20 Ohms ... (probably due to ionic salt residues in Pot)
3) H₂SO₄ & Pot 2.5V, 1A = 2.5 Ohms
4) H₂SO₄ no Pot 1.5V, 1A = 1.5 Ohm
5) CuSO₄ & Pot 2V, 1A = 2 Ohm
6) CuSO₄ no Pot 1V, 1A = 1 Ohm

So with 1M sulphuric acid OR 1M copper sulphate solution,
these particular porous pots add about One Ohm resistance.

EDIT: Notes;
The voltages were read on an analogue dial 0-30V meter built into the power supply so are very approximate.
I suspect that the Pot resistance measurements would be lower if I had dried the pots and then pre-soaked the pots in their electrolytes.
These were quick-and-dirty measurements, use them as an indication only.
The water measurement was done on two pots/vessels/cells concurrently,
since both cells gave similar results,
the others were done using one pot/cell for CuSO₄ and the other for H₂SO₄
The copper sulphate solution was probably slightly less than 1M
because even though I used the correct weight of copper sulphate per litre,
it was cloudy / not all crystals completely dissolved.

The 1M copper sulphate being more conductive than 1M sulphuric acid was a surprise result.

[Edited on 20-7-2018 by Sulaiman]

JJay - 20-7-2018 at 07:32

Nice work. I need to buy some agar....

Boffis - 25-7-2018 at 05:14

I found that piezometer tip filters can be used. Normally the pore size I too large but this is easily overcome by dipping them in sodium silicate solution and then mopping them dry before dipping in dilute HCl and finally wash with water. They bleed sodium and chloride ions for some time so you may need to run a few blank runs to clean then out but I suspect that they need some ionic impurity to keep the resistance low. You can use any appropriate support for this type membrain providing it is wetable with sodium silicate solution. They don't like being dried out though so keep them wet.

JJay - 26-7-2018 at 04:08

That is interesting. It looks like the membranes used for piezometer tip filters are available with standardized and predictable properties.

Laboratory of Liptakov - 12-3-2019 at 12:04

Did anyone use a ceramic tile? Like a membrane? It is very cheap and the surface is large. Tiles can be cut. But mainly easy to get rid of glazing surface. Disc grinder. The tile thickness can also be reduced by a disc grinder. For example, from 5 mm to 3 mm. An aquarium can be used as a bath. A silicone sealant can be used as a sealant for the membrane (in the middle). Ordinary silikone (acid) sealant is resistant to Cl2 and ClO2. Tested, confirmed. Materials that Resist Cl2 and ClO2: Titanium, Silicone, Plastic NaClO2 Cleaner Bottle. Other plastics and metals dissolve in hours or days. The silicone is unchanged. Another idea is. Use these two described modified tiles. For example with a 2 cm gap between. And fill dry NaCl between them. Pour dH2O and create porridge from NaCl. Like a salt bridge. The salt bridge maybe will automatically maintain a high level of NaCl concentration which we need during a process). And maybe it will create an effective diaphragm. It's just an idea, it's untested. Carbon rods can be used as anodes. I'm talking about a cell on NaClO3. Maybe shloud by this device decrease erozing of carbon rod. Maybe should by possible preparate even perchlorates in this device.

markx - 12-3-2019 at 13:31

One also might try the ceramic CO2 diffuser discs meant for planted tanks as a cell membrane. They are sintered glass I think....very fine in terms of porosity....and often come supplied with silicone gaskets. Easy standard sizes that can be readily adapted for a cell membrane application without further mechanical manipulations regarding shape and size.

Laboratory of Liptakov - 14-3-2019 at 12:18

English Text extract from patent:
We have found by actual tests that with an apparatus constructed as above described, provided the anode is surrounded by any appreciable quantity of the acid solution, we can , on a commercial scale, continue to convert the chlorate until practically the whole of it is changed into perchlorate, for our tests shows a conversion efficiency of say 50% or greater of the total amount of current employed-------Prior to our invention, it it has been erroneously believed that no commercial quantity of perchlorates could be produced in an electrolytic cell using a carbon anode. This erroneous belief belief has been founded partly on the fact, that the oxygen liberated at the carbon anode in an acid solution gives rise to a disintegration, or oxidation, of the carbon material. And hence it was thought that such disintegration would be sufficient to destroy the anode to such an extend as to make the process ompracticable commercially.------- Further, it is a well recognized fact, that, if the solution is mantained neutral or alcaline throughout the process, the the discharge potential from a carbon anode will not be great enough to commercially form perchlotates.-------In carrying out our process, we employ an anode consisting essentially of carbon, or of silicon, and preffer to start with an acid solution of the chlorate corresponding to the perhalate to be made, but of course, we may start with neutral, or even alcaline solution, and permit the action of the current to render the solution acid as the process proceeds.--------We prefer three to twenty amperes per one hundred square centimeters on the anode surface, and it is also preferred to keep the solution cold during the entire process. As the current passes the usual cathode reactions take place in the hydroxid solution 6, provided of course , sucha solution surrounds the cathodes 4, and at the anode 3 likewise, the usual reactions will take place which in this case consist of the discharge of the oxygen ions from the water, and the reactions of this oxygen with the chlorate ions at the surface of the carbon anode.-------This last mentioned reaction will form perchlorate ions and free electrons which pass out through the pole. The hydrogen ions left from the water molecules of which the oxygen has been used up, remain free in the solution and render the same acid in character.-------The anode is surrounded by any appreciable quantity of the acid solution, we can, on a commercial scale, continue to convert the chlorate until practically the whole of it is changed into perchlorate, forour tests shows a conversion efficiency of say 50 % of greater of the total amount of current employed. On the other hand theseresults are impossible if the anode is in contact with an alkaline solution.-------Our tests further show that although a small decomposition of the carbon anode actually takes place, yet, it has not proved to be at all prohibitive, and in some cases it has been as low as 9 % by weight of theweight of the perchlorate produced.-------Hence to overcome both of these sources of trouble, we have separated the cathodes 4 by porous diaphragms (5) from the anode liquid , thus preventing access of the acidified chlorate solution to the cathode and its consequent reduction to the chlorid.------- We have further discovered that the decomposition of the carbon anodes may be greatly diminished and the current efficiency increased, by the following treatment, preliminary to their use: heating the anodes, plngining them into a bath of melted parrafin and allowing them to remain until cool, whereupon the outer conducting surface may be exposed by mechanically cleaning off the excess of wax like material.------- This treatment not only prevents the solution from penetrating into the pores of the anodes, thus causing a mechanical disintegration by the evolution of gases therein, etc, but it also limits the active surface to an outer surface of known extent, and makes it possible to provide a definite current density. This latter is very diserable, because,too low or too high a current entails a lower current efficiency.
The claim 6:
The process of producing sodium perchlorate and perchloric acid which consists in electrolyzing an acid solution of sodium chlorate, with an anode of carbon, and separating the anode liquid from cathode , substantially as described. In testimony whereof we affix our signatures.
Eugene Paul Schoch.
Rufus Hubbard Pritchett.

markx - 15-3-2019 at 00:43

I've seen this patent, but for the life of me I can not figure out a reasonable explanation as to why in the separated anode compartment the perchlorate formation on carbon electrode would be more successful than in a cell with no separation?
I mean the lack of cathodic reduction could not be the only cause. And the perchlorate formation takes place around the anode, so if the material is not able to provide this property in a nondivided cell, then why should it do so in a separated one?
Perhaps I'm missing a critical point here....

Tempting though, I guess in time I shall test this kind of a setup. I've already got the carbon dioxide diffuser discs for the purpose. Just got to come up with a reasonable cell design. Soaking open clay pots in solutions does not sound like a very appreciable approach

cell on NaClO3/4

Laboratory of Liptakov - 17-3-2019 at 11:16

Maybe will works it: Important is big surface the carbon rod. For low current load on rods. And temp. 40 C I estimate. Double diaphragm should by works as saturator NaCl for both sides. Between ceramic tiles should by crystallic NaCl as consistency as the porridge. Thus holding high concentration of salts on both sides. And maximal conduction. Maybe . Not tryied was it. Higher level of solution in saturator bridge prevents mixing between the two liquids sure. Maybe will in this model too much high teperature and converzion on NaClO3 minimal. Because double diaphragm sure will increase the electric rezist. Is it only scheme model. Not more.