Author Topic: Cation Exchange Membrane  (Read 843 times)

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halfapint

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Cation Exchange Membrane
« on: June 25, 2002, 02:59:00 PM »
All right, I priced Nafion membrane and I'm still kind of in shock. $150 for a square foot? Excuse me, 30 x 30 cm. This exemplifies the type of protection our patent system gives to capitalist pigs, for Dupont probably makes that film for about 11 cents in material... Second sourcing would lead to rapid development and adoption of fuel cells in our world... Half-a-Pint's still ranting.

So what's the back-up plan? The clearest first choice looks like sulfonated polystyrene. Chemists use it in their chromatography columns. No problem. Lo and behold, it's even in water softeners, as the sodium salt, crosslinked with divinylbenzene. OTC and easy. Well, I don't have a water softener, or I could just go and dip out some of the beads, squish them down with heat until they melted onto a fiberglass or cellulose fabric, and have my membrane.

I could pretend to have a water softener, and go get a handful or so of that resin. Here the structure of the economy gets in my way again. Water softeners seem to come in a standard size, 32,000 grains, one cubic foot, 52 pounds where I live. What will I do with the extra 51 3/4 pounds of resin beads? I got friends, but it's not easy to come up with a cover story for taking their water softener apart.

Hmm. Guess I'll need to go to some real chem supplier, and get a rational quantity of cation-exchange resin, dowex or whatever. I just hate to deal with those people, for private reasons, plus I'd have to get ready for another outrage when I find out what it costs. Can I build this stuff for myself?

Seems like if I ground up some polystyrene foam and stuck it in some sulfuric acid, and heat it a bit, I'd get a bunch of black sticky crap that I could call sulfonated polystyrene. I would spend a lot of time making a great mess, trying to get it to harden up and adhere to the backing material. It just seems doubtful that I would ever be willing to use anything like that in my electrochemical cell, for fear of contamination, leaks, etc.

I wonder if polyphosphoric acid might work as a membrane material, I make that by heating naval jelly, but in my highly alkaline medium I would expect it to simply dissolve away. Hate to get stuck this way. Any beez have any suggestions for me?

a half a pints a half a pound a half a world a half a round
Sidearm n. Flask neck tube.

terbium

  • Guest
What is it for?
« Reply #1 on: June 25, 2002, 04:06:00 PM »
If you want suggestions of substitutes it would help if it was specified exactly what it was for.

halfapint

  • Guest
Terbium, that's a secret!
« Reply #2 on: June 26, 2002, 02:35:00 AM »
Just don't tell anybody about it, cuz I want to take this to the market. Not the real corporate commercial market, but the quasi-private trading of auctions and ads and stuff. Out in the real world, I might get asked weird questions about liscensing and infringement and stuff I never want to hear about.

But let's say that ain't true, let's just say for now I want to produce just exactly enough sodium borohydride and lithium borohydride for my own private use, with perhaps a bit left over for a couple of my future incarnations. I mean to implement US 3734842 for the electrolytic production of sodium borohydride. Feedstocks are sodium metaborate in the cation chamber, and lye in the anion chamber, neither real costly. The cathode should contain reduction catalyst, e.q. hydrogenation catalyst, and/or have such catalyst in its chamber, something I can arrange. NaBH4 has decreased solubility in alkaline solution, and will tend to precipitate, making its partial, continuous recovery a breeze.

Well, that's my plan. If you see anybody offering dutch auctions for 100 g lots of NaBH4, that's not me. If it happens to bee LiBH4, I'm the one selling the ten foot pole I wouldn't touch the stuff with.

a half a pints a half a pound a half a world a half a round
Sidearm n. Flask neck tube.

foxy2

  • Guest
nafion
« Reply #3 on: June 26, 2002, 04:19:00 AM »
That stuff is very interesting.
Lots of good uses.

I'll take the scraps

Those who give up essential liberties for temporary safety deserve neither liberty nor safety

sYnThOmAtIc

  • Guest
So what is wrong with nafion
« Reply #4 on: June 26, 2002, 05:57:00 AM »
Man jusy buy a square of it its enough to make 20-30 cells. You could have a elec-wacker cell, reduction cell, peroxide cell, man you could have a separate cell for every thing youd like to make yourself. BTW you can make everythng from formic acid to conc. peroxide anyhitng you can think of really cept a few things maybe.

Osmium

  • Guest
> So what's the back-up plan?
« Reply #5 on: June 26, 2002, 12:19:00 PM »
> So what's the back-up plan? The clearest first choice
> looks like sulfonated polystyrene. Chemists use it in
> their chromatography columns.
> Well, I don't have a water softener, or I could just go
> and dip out some of the beads, squish them down with heat
> until they melted onto a fiberglass or cellulose fabric,
> and have my membrane.

Crosslinked polymers don't melt anymore.

> Seems like if I ground up some polystyrene foam and stuck
> it in some sulfuric acid, and heat it a bit, I'd get a
> bunch of black sticky crap that I could call sulfonated
> polystyrene.

Dissolve polystyrene in solvent, treat with H2SO4 or chlorosulfonic acid, purify by repeated precipitation in a non-solvent (e.g. MeOH). Determine amount of sulfonation by acid/base titration in THF or similar solvent.
Prepare solution of the purified sulfonated polymer, cast it on a glass plate, let solvent evap and remove film carefully. Play around with reaction parameters like amount of sulfonating agent, temp, duration and concentration of polymer in final film casting until you get it right. Easy as pie, just a bit tedious.

I'm not fat just horizontally disproportionate.

UTFSE

  • Guest
.5pt check Journal of Chemical Education online ...
« Reply #6 on: June 27, 2002, 12:52:00 AM »
.5pt check Journal of Chemical Education online for ion exchange resins - seem like they might help - don't remember exactly. if you can't get the article you need let me know pm. have access to all JCE's.

also check American Scientific that also rings a bell.

there is a way for you this day. sticky gooey passing thru that is.

NaBH is one of my favorite subjects.

OTEECEE & meeeee!!!!

halfapint

  • Guest
Glorious few days
« Reply #7 on: June 27, 2002, 08:37:00 AM »
Appreciate everybee's contributions.  JCE and SciAm, eh? Osmium's input seems particularly useful. Knowing I can't remelt sulfonated polystyrene saves a false start. (A thick "membrane" made of such beads or granules would decrease electrical efficiency, by increasing the cathode-anode spacing.) Another bee whom I greatly respect has privately provided invaluable input.

A possible alternative I found today at USPTO is in US 4051002 Electrodialysis for aqueous solution of base. They build a membrane from "a copolymer of ethylene and an unsaturated carboxylic acid" like acrylic, maleic or fumaric, then give various ways to fancy it up. Even with a gaseous reagent, this sounds conceptually simpler. Well, I've never done a polymerization reaction, at least not on purpose, (though I have discovered several novel ways to polymerize asarone!) The grandfather of sulfonated polystyrene/divinyl benzene patents AFAIK seems to be from 1942, US 2366007 to GE.

I have learned today that thin membranes may bee cast on the surface of water, say in a glass loaf pan, between two glass rods which are slowly spread apart as the polymer is gradually streamed in and congealed. Then you may pick it up with suction through sintered glass to avoid stress. Fascinating.

The Hive will hear of any success stories in this area. Meantime I'd bee obliged if some other individual would unass their big stash of NaBH4 on line to protect my cover...

a half a pints a half a pound a half a world a half a round
Sidearm n. Flask neck tube.

Osmium

  • Guest
All these polymers are available for free when ...
« Reply #8 on: June 27, 2002, 12:33:00 PM »
All these polymers are available for free when you find a manufacturer and ask for a small sample. Aldrich sells a lot of them too, usually at 10-20 times the usual market price (fuckers). Do not bother trying to synth them yourself, spend the time at google.com searching for manufacturers instead.

http://www.psrc.usm.edu/macrog/ionomer.htm



I'm not fat just horizontally disproportionate.

sYnThOmAtIc

  • Guest
OR jsut purchse it
« Reply #9 on: June 28, 2002, 02:58:00 AM »
Why go through all this trouble when you can buy the stuff in bulk for under 50 bucks a kg? Though there is a minimum order for such a price with a small investment you would have enough boro to clean spent plating solutions of every electro-plater in the country each week for a year.

UTFSE

  • Guest
symPtoMtic - yes just reach up on the ion ...
« Reply #10 on: June 28, 2002, 07:21:00 PM »
symPtoMtic - yes just reach up on the ion exchange resins shelf and get that big ol jar down and go for it.

or having not the desired substance and not really wanting to attract - oh so too much attention.

OTEECEE & meeeee!!!!

ClearLight

  • Guest
ghetto...
« Reply #11 on: June 28, 2002, 11:02:00 PM »

 Swim spoke with my Membrane guru... he laughed and said use a lambskin rubber... if swim wanted larger, get the ceramic filters used to partion/filter aquariums...

  Says the rubber is good for 1x or 2x... but at the price, hard to beat..


Infinite Radiant Light - THKRA

sYnThOmAtIc

  • Guest
No seriously
« Reply #12 on: June 28, 2002, 11:54:00 PM »
40kg for 40a kg.. Hell they will send you a small sample for free or if a larger is needed they will sell you 25lbs at 25bucks a pound. As long as you keep it profesional and can provide the right type of business licenese they are very eager to get your money and your package. They ship it as sodium borate h4. Of course I never bought any only inquired one of a couple of people who turned them on to me have made purchases. I just recieved theri 100g sample for  use in my lil $25 prebuilt cup shape fuel cell

BooWho

  • Guest
Cation Exchange Resin
« Reply #13 on: July 05, 2002, 02:31:00 AM »
Boo just acquired a large brown jar of this material.
For now it will have to sit in his cabinet as he doesn't have the faintest idea what to do with it.
But soon... very soon...

boo

As if by destiny,
Laughter turns to tears....

BooWho

  • Guest
A new source discovery
« Reply #14 on: July 12, 2002, 12:01:00 AM »
Boo was out shopping the other day and came upon a product that has the cation exchange membrane contained within it. It is a water filtration cartridge that is made by P*r... and is the P*r plus filter.
Short of naming it here PM Boo for more details as this was a very cheap way of procuring this material.
boo

When I'm standing next to a mountain... I chop it down with the side of my hand...

jimwig

  • Guest
aka " standing next to a cation - chop it up with ...
« Reply #15 on: September 05, 2002, 07:25:00 PM »
aka " standing next to a cation - chop it up with edge of my blade "   

also -  so long half-a-pint     "if I don't see ya no more in this world I'll see ya in the next one - and don't be late .   .    ."


sYnThOmAtIc

  • Guest
What was jimmy saying in that phrase?
« Reply #16 on: September 07, 2002, 10:06:00 PM »
What was jimmy saying in that phrase? What the hell is standing next to a cation?

Yes, That pic really is me!

jimwig

  • Guest
the license to travel ----
« Reply #17 on: September 18, 2002, 02:59:00 AM »
emotionally, poetically, metaphorically, spiritually.

i personally think that was the most literal line in any of his lyrics. and i guess i was following suit.

one pill makes you smaller and one pill makes you tall and the one your mother gives you don't do anything at all

when in roam ----

btw its jimi.