Sciencemadness Discussion Board

Diaphragm cell (pictures)

plante1999 - 18-12-2013 at 13:54

I just started building a very crude prototype of diaphragm cell using polypropylene food container. I used an asbestos diaphragm supported by a cheap iron sheet with drilled holes. A mesh would be better. One top and a bottom had an hole cut in them and they were soldered together. The cathode is supported on the side of that. There is no catholyte in a diaphragm cell in general, the asbestos serving that purpose. See the pictures for more details...

P.S: Sorry if the writing seams botched, as been 4 time I write for 20 min the posts and when I post it it does not post...


http://i1103.photobucket.com/albums/g469/plante1999/DSC00229...

http://i1103.photobucket.com/albums/g469/plante1999/DSC00234...

http://i1103.photobucket.com/albums/g469/plante1999/DSC00235...

http://i1103.photobucket.com/albums/g469/plante1999/DSC00238...

http://i1103.photobucket.com/albums/g469/plante1999/DSC00241...

http://i1103.photobucket.com/albums/g469/plante1999/DSC00244...

Paddywhacker - 18-12-2013 at 14:07

> P.S: Sorry if the writing seams botched, as been 4 time I write for 20 min the posts and when I post it it does not post...

Yeah, I've learned to highlight and copy my text on some boards so that I can repeat it with just a Ctrl-V if it fails.

Is that asbestos fiberboard? I haven't seen any of that for years.

It will be interesting to read how it works out. I would have thought that the iron, mesh, or any conductor, would polarise with one side an anode and the other side a cathode.

[Edited on 18-12-2013 by Paddywhacker]

plante1999 - 18-12-2013 at 14:15

I think I will try that next time...

It is an asbestos fiber sheet, grandfather had a few sheet left which he gave me long ago. The anode is in the top solution while the cathode is directly on contact with the asbestos. The NaOH drip from the cathode to the bottom container.

Here is a rough idea of the cell.



[Edited on 18-12-2013 by plante1999]

Diaphragm cell.bmp - 871kB

blogfast25 - 19-12-2013 at 06:13

Is this to illustrate/investigate the general principle of a diaphragm cell or for actual production of lye solution? What power source are you using?

plante1999 - 19-12-2013 at 13:24

Simply investigating, as if I build one for use it will be made with soldered plastic for cleanness and precision, maybe acrylic to make the design perfect and another plastic for the lasting one.

blogfast25 - 20-12-2013 at 05:48

And the power source?

plante1999 - 20-12-2013 at 06:08

My usual 1940-1970 erra 3-7 V variable power supply made of 1/4 al plate. Rated 10 amps.


We see it well there:

http://i1103.photobucket.com/albums/g469/plante1999/009-1.jp...

blogfast25 - 20-12-2013 at 09:49

It'll be interesting to hear what concentration of NaOH you can reach and what kind of problems you will (inevitably) encounter.

plante1999 - 21-12-2013 at 05:33

In industry, the concentration is said to be 15%. That is mostly why the mercury process was mostly used at the time the membrane process was not yet commercialized.

blogfast25 - 21-12-2013 at 06:03

The real 'fun' is to get solid lye from that! ;)

macckone - 23-12-2013 at 23:31

Interesting design.
what flow rate is the pump?
And how are you processing
the hydroxide solution?

testimento - 9-2-2014 at 15:01

This is very interesting!

Could the asbestos be replaced with something else, like modern syntetic ceramics?

This idea might sound very stupid and amateurish, but would micropore tape work? This could be literally taped onto a glass wool or similar thin material and placed onto cathode plate as in pic.

What about gore-tex membrane?

[Edited on 9-2-2014 by testimento]

macckone - 9-2-2014 at 20:03

Quote: Originally posted by testimento  
This is very interesting!

Could the asbestos be replaced with something else, like modern syntetic ceramics?

This idea might sound very stupid and amateurish, but would micropore tape work? This could be literally taped onto a glass wool or similar thin material and placed onto cathode plate as in pic.

What about gore-tex membrane?

[Edited on 9-2-2014 by testimento]


Anything that won't dissolve or be otherwise damaged in 15% NaOH and will provide sufficient resistance to flow should work as a diaphragm.

Some HEPA vacuum cleaner bags are made of polypropylene and
have a very small pore size. I would think several layers of that
might do the job. I know they work for filtering.