Electrolysis membrane

[Bandil]

Hi!

I was just testing some membranes for cell divided electrolysis today, for my reduction tomorrow. I used an unglazed clay pot, and filled it with dilute HCl and some dilute HCl on the outside. I really didnt expect to be able to pass current through it, but i wanted to be sure, before making sheep gutted version tomorrow. As expectet not a single milliamp passed through. I used 15 V on each side of the pot wall(cleaned it thourghly etc) attached to lead electrodes.

Have either of you been able to pass current through one of these buggers? I doubt it, so ill by some sheep gut from the butcher tomorrow. I have higher hopes for this material! I will of course post my results, as i am attempting to reduce with Zn-HCl and electrolytical at the same time.

Regards
Peter

[hest]

It take some time for the acid to penetrate theclay (houers), before that it's a good insulator.

[Bandil]

So i have to leave it in the solution for a while? I guess it does not have to be hooked up on the current meanwhile. The claypot is currently soaking 10% HCl. Is that doable, or should i usem what i plan on using for catholyte?

Regards
Peter

[hest]

Sounds good to mee.

[Bandil]

Allright! This morning the clay pot pulled 0.2 A at 24V... Its somewhat better than 0.0A, but still not good enough. Dp you think the conductivity will improve, if it is soaked for another 24 hrs?

[hest]

No, not much. mabee a bigger elektrode/setup ??

[Bandil]

No... The electrodes had a surface area of about 15 cm2, which gives it a current density of 0.013 A/cm2(thats a bit small right?), which is way to small. I really dont want to regulate the voltage more up, as it already is 24 V. I think ill have a go with the lamb gut setup.

Ideas?

Regards
Peter

[Bandil]

Just attemped electrolysis with pig intestines as membrane. The g... da... thing broke after two minutes of running. So much for the natural approach!

I will try to get other materials for the membrane. In first attempt it will be a flower pot with thinner walls.

Any ideas for other practical materials for use as membrane?

Regards
Peter

[Rhodium]

A fritted glass disc? They are available in all porosities from chem equipment suppliers.

[Bandil]

Do you have more details on the membrane? Name etc... Is it something that can be bought from Fluka or alike?

Thanks
Regards
Peter

[Rhodium]

Not chemicals suppliers, but rather those selling glass and equipment. I have no exact source in the US.

[Osmium]

I hope you didn't use 15 or even 24 volts on those intestines.

What about dialysis membranes? Anybody ever tried that?

I've seen soft polyurethane foam being used in electrolysis reactions. Improvised and ghetto, but it worked (or so I was told).

[Bandil]

I looked at dialysis membranes some time ago, and boy did i get confused. There where cathion one way, both ways, protein permitable and yadeyadeyade. There where litteraly 100's of different types, so i did not know which one to get. Any ideas on which ones of the dialysis membranes, that would work?

Regards
Peter

[Osmium]

The cheapest, most general one. Or the one with the prettiest colour  

Since the current is transported by the movement of the water molecules the pore size doesn't have to be big at all. Smallest pore size should be more than adequate, and will also help keeping the solutions separate.

I really don't know if it will work, just an idea. Ask the manufacturer for some free samples and find out if it works and which one is best.

[Antoncho]

Or the one with the prettiest colour  

Speaking of which - i don't know if a regular condom would pass molecules of water but it surely lets through gaseous HCl - at good rate, BTW! (And i used some really tough, studded Soviet condoms from my late grandpa's stock )

HCl molecule is bigger than H2O, does anything else matter?

You also might have to stretch it for this.

Antoncho

[pimpmaster]

need a membrane how´s about this procedure. wet a sheet of paper, wrap it several times around a large test tube or beaker,folding it in to close at the bottom. mold the paper into shape, then coat it inside out with a solution made by dissolving 75 grams of gelatin and 100g K4Fe(CN)6 in one liter of water. When the cup has drained and cooled it should be removed and inverted until dry.
sounds nice except for the K4Fe(CN)6 i wonder what could be used instead ?

[sYnThOmAtIc]

Wow people are finally starting to get into electrochemical cells lately.... Pinky is using a stainless steel cup in a pot of acid for his reduction. No worry about goods being oxidised since there is absolutely no particle travel but conducts electricity fine. Machined carbon cups and unglazed fritted porcelin mugs can be bought and work much better thatn clay.

[Natrix]

I think gore-tex could be used for a membrane.

[dwarfer]

.2ampsat24 v is an unusually low current for that V:

?? get another pot:

10 V should give you 2X that much: although without knowing your set up, this is specious reasoning...

The worlds easiest set up is a standard pot inserted into the BOTTOM of a cut-off 2 liter soft drink bottle.

The cathode is in the bottom, symettrically placed, the teflon wrapped current supply wire passes through a sealed hole..

There IS a standard pot which will JUST FIT, and the tera cotta RIM rests on the rim of the cut off bottle...

Note that this seals the catholyte from air, enhancing appropriate reactivity therein

Now you take another 2 liter soft drink bottle, cut it off at the appropriate height to accomplish the following:

1.  melt a hole in the screw cap 3/8 diameter to pass the carbon electrode anode which you got from a welding supply shop for $.50

2.  A standard condom will be passed thru the screw on opening from the bottom, maybe 1/2 inches worth, and the screw on cap will be screwed on tightly enuff to hold it in place, and not so tight as to rip it. They ARE tough..

3. the top section will be placed INSIDE the tera cotta pot:
this will necessitate 3 verticl slits symettrically place so the "legs" thus form can overlap to accomodate the reduced diameter of the pot inside...

4.  The height will be adjusted so that the condom reaches down to about an inch from the pot bottom.

5.  Your 10 to 15% HCl will be added to the pot, and to the condom through the anode hole, keeping the levels about thesame.

6. You will insert the anode, NOT allowing contact with the skin.

This dual membrane system will have significantly less R than your set up: probably because of the large submerged pot surface area.

It was found to be as effective as a pressurized systemI built in reductive process.  And takes about maybe an hour to build...

I'll take some pictures...

             
dwarfinger: He's the dwarf wit' der GOLdenNose <hmm>

[Antibody2]

please do dwarfer
"All those memories lost like rain..."

[Bandil]

@sYnThOmAtIc>

A stainless steel cup? Interesting indeed, but there are some things i am not quite sure of here:

a)
Wont the metal be dissolved over time, because of various side reactions?

b)
How can it conduct current, when it does not allow ions to pass, which are the ones responsible for the current?

How are your yeilds using this method?

Regards
Peter

BTW: Great idea...

[sYnThOmAtIc]

This is a little off topic but is realted to the electrochemical reduction.

Could the procedure for making pt and pd on carbon catalysts be applied to a section of carbon rod? As a pd/c electrode could be quite helpful to improving yields in the amination of ketones to sec. amines wiht an electrochemical cell.

[sYnThOmAtIc]

I meant it doesn't allow the reactant molecules to pass but does allow current to pass. Dunno about yields as pinky is still piecing together a procedure for the reduction. But in tests his partitioned cell worked fine.

It consists of a dispensing vessel submerged in a glass carboy with top hacked off the carboy. The bottom of the carboy has a piece of graphite plate in the bottom cut to fit in the bottom. Then the carboy was filled halfway with NaCl solution and the vessel is lowered into carboy and filled with NaCl solution and a graphite rod is lowered into the vessel and a current is appied. Chlorine gas is evolved in the vessel and Iodine can be seen collecting on the graphite in little clumps.

With an acid solution substituted in the carboy and ketone/amine in vessel reaction should be a success if a proper cathode is used in the vessel.

[terbium]

I meant it doesn't allow the reactant molecules to pass but does allow current to pass.
A stainless steel cup!!! I am beginning to suspect that you have zero knowledge of electrochemistry.

[sYnThOmAtIc]

Gee which is exactly what I stated in the post about NaCl electrolysis it's not a big secret. Besides whats your itch today? If you have a better idea then post it and quit burning my ass. I'm just trying to help as much as I can with what I have. Hell I'm just barely old enough to be out of highschool and if I had about thirty grand maybe I'd buy some education in the field, if some other field doesn't interest me more.

[Bandil]

@terbium>
Could you please comment why it is a bad idea? I woudl suspect that the steel walls, would work as either a intermediate cathode/anode, reducing/oxidizing, whatever product that has been reduced.

Regards
Peter

[sYnThOmAtIc]

Cause stainless steel is the most unreactive metal to acids and strong chemicals without putting a bunch of impurities into the solution, while keeping the solutions in each compartment separate. Any pourous membrane is gonna leak some goods to be oxidized and lost resulting in a loss in yield. Unless you order a special and most likely expensive membrane of some sort. I'm trying to use the cheapest most readily available components while still obtaining good results.

 If this could be done with a pyrex dish and a few pencils and dog food bowls along with some wire and a transformer imagine what kind of leap this would be in the war. And I'd like to see the DEA keep people from buying graphite and stainless steel. HA!

Besides even if I'm no expert as you may be that is what this place is for to help each other  overcome thses bulshit restrictions. And quite frankly electrochemical reactions look the most promising in the defeat.

Anyway back to the subject. As long as the anode is not in contact with the stainless dish then no oxidation will occur in the compartment or else Cl gas would have evolved in it when powered up but it didn't only Cl came from anode and none at al from the sides of the dish, as was expected. So as long as the stainless steel is of reasonable purity then ther should be no problem with any side reactions.

[Bandil]

I cant see how it would work, without working as anode/cathode at the steel wall. Something has to be oxidized/reduced in order for the system to conduct current. It is a good idea, but i have a hard time seeing how it is different from a one celled electrolysis w/o membrane. Sure the steel keeps the products from mixing, but the reduced PEA, would simply float to the steel wall and be oxidized.

Im not saying this as facts, its just the only way that i can make the system work in my mind. Please someone tell me that im wrong, as it would be a really easy way to do it!

Regards
Peter

[lugh]

Hell I'm just barely old enough to be out of highschool and if I had about thirty grand maybe I'd buy some education in the field, if some other field doesn't interest me more

There's more than one way to skin a cat, in this particular instance a visit to a local public library (generally free   ) would exponentially increase your creativity. While education is a good thing, few universities teach electrochemistry    

What terbium is getting at is the function of the cup/membrane/diaphragm in electrolysis is to allow certain ions to travel through the diaphragm and reach the electrode, while not allowing other species to penetrate. Obviously, stainless steel isn't permeable, and thus not suited for this purpose.

[PrimoPyro]

Allow me to interrupt just once and very shortly:

lugh! CONGRATULATIONS on the promotion!  

Alright, Im done. (slinks away)

                                                  PrimoPyro
Vivent Longtemps la Ruche! STRIKE For President!

[Bozakium]

Have you tried lambskin(not rubber) condoms? Fester has had good luck with these as cell dividers.

[TrickEMethod]

I am somewhat out of date as to the status of everything, been on hiatus from the world of creative chemistry.  About six months ago, I was playing with the Fester
electrochem method with minimal success before I was so rudely abducted by aliens.

At that time I was using lamb skin condoms with no problems whatsoever, but I had rigged up a fairly effective ghetto CV/CC (constant voltage or constant current) power supply($100 from simple Walmart and Shack components).  I had also begun digesting several hundred pages of papers and books on the various factors governing electro chem reactions... cell design, current density, temp control, circulation, cathode\anode selection and solvents were all significant to the outcome of the reaction. 

I need to refamilarize myself with the subject for sure, but one thing stands out from what I gathered very distinctly; small or even unnoticed variations in the configuration can impact the results dramatically.  Since the literature provides a number of frameworks to anticipate and calculate the impact of many of these factors, I would encourage you to sketch a few impact estimations for yourself to get a ballpark feel for the significance.

It is well documented that subtle variations can lead to highly diverse outcomes, with many interesting possibilities for additional research identified but as yet resolved.  I learned first hand that propper control of the voltage potential, solution temp and monitoring shifts in the current flow were minimum ante for predictable results using this method.  Getting a successfull result from a car charger, run blind with ambient cooling would seem as likely as picking a catalyst, reaction temp and solvents at random.  It could happen... but not often.

I didn't mean to preach, and I certainly havn't perfected this strategy.  But I did become aware of some of the loose ends that were being under appreciated.

TrickE
BTW, if anyone is interested in construcing a powersupply it is described in an older post.  A $60 Shack multi-meter with rs-232 output is used to monitor the output of a PC driven power source.  The power source is simply a cheep($35) 80 watt audio amp driven by a PC sound card.  The amp delivers a modulated signal (AC), which is rectified and smoothed with a medium sized capaciter.  Software reads the meter and adjusts the 'volume' of the tone output to make necessary adjustments.  The software not only controlled the feedback loop, but as a bonus, plotted the effective conductivity using fairly basic factoring and estimation methods to provided helpfull clues to the progress of the reaction over time.  (actually this wasn't finished, but fairly staightforward)
And on the eight day, God created Meth...
... and hasn't done much of anything usefull since!

[foxy2]

Nice TrickE

Are you going to write a comprehensive electrolysis FAQ when you get your apparatus built?
Do Your Part To Win The War

[sYnThOmAtIc]

Alright how bout this one....

Fuel cells, they use noble metals/and oxides as electrodes some gas diffusion and solid that not being that important but the vulcan/nafion/and carbon cloth membranes can be bought cheap precut for use in a fuel cell or custom ordered sizes, but still cheap. Electrodes can be bought really cheap with a 20% loading by wt of a choice of sitloads of metals a few being  pt/pd/ru/ni/and their oxides for about 1-2 bucks per cm2 solid and porous some hydrophobic or teflon resin backed blah blah bla... they come on carbon or a variety of other mediums some specailly for use in acid and alkaline cells nafion112-117/vulcan xc72 with teflon coating would be good for chemical resistance .. so you can purchase the pieces and rig a setup or if you have simple machining equipment you can put together a fuel cell yourself for about 1/80th of what these price gougers sell theirs for and have a 3kw cell to help save on the electric bill. Or you really get into it and invest a lil the you can have all your electricity and vegies/spices for free as long as you have sun a water oh and a halide light or two. But back to the point, those who at least under stand the aspect of electro oxidations and reductions should see the usefulness in this if not then jsut ignore this post. Most all cells I have looked at are easily dismantled by removing the bolts from the sandwhich array which can then easily be altered for your purposes electrolysis/power generation oxidation/reduction blah blah yadda yada.

[Bozakium]

Keep it simple and save your sound card, thats way too Rubie G-berg.. An LM317 voltage regulator can also be configured as a current regulator with only an additional resistor.   BUT You want to regulate voltage rather than current with electrochem rxns because the various reactions that can occur with a given compound are V dependant, and, while keeping V steady, current will fluctuate as electrolyte composition changes during the rxn.
 What I'm trying to come up with is an integrator circuit that(not integrated circuit, DUH) that will integrate current with respect to time (dI/dT) to give an output in coulombs. This would be very tidy since cell current varies and constantly plotting it is apain in the ass with other things to watch in the lab.
  OH yes, the fuel cell people have mannnny interesting things available...........

[Bozakium]

I read in an old chem text that hollowed-out fruits and vegetables can be used. If you're interested, I'll look it up, or you can just experiment!Im serious.

[Osmium]

What about hollowed out roadkill? W need a use for the hide too, after we isolated lactic acid, GHB and cadaverine from the meat and P from the bones.