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Jstuyfzand
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[*] posted on 21-3-2016 at 14:07
Chlor Alkali Membranes


I am planning on building a chloralkali cell to then make hydrochloric acid
By burning the hydrogen and chlorine and dissolving it.
This is not the most efficient process, I know, but I it is relatively easy and I find making my own materials fun and educational since I am wuite new to chemsitry.

My idea was to connect 2 soft plastic bottles with a 1" plastic tubex with a membrane in it.
I have heard of people using drywall and filter paper, and salt bridges.
I myself dont see how the salt bridge and filter paper wont leak into the solution, and isnt drywall gypsum? That cant handle water....

If anyone could comment his experiences with these membranes, or some easy alternatives that are readily available, that would be awesome!

Ps: I have tried the flower pot, did not went well.
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[*] posted on 21-3-2016 at 15:36


http://www.sciencemadness.org/talk/viewthread.php?tid=2154
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[*] posted on 21-3-2016 at 17:17


"Making a short story long??" Good call Neuro! It sounds like a lot of fun but dangerous so please take care and avoid sparks. and remember the search engine.. inefficient as it sometimes is. Since you're new: we try to include references. You get better answers that way. Also it shows you've done some work before asking. That's basic courtesy. Welcome to you and have fun here.



"When you let the dumbasses vote you end up with populism followed by autocracy and getting back is a bitch." Plato (sort of)
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[*] posted on 21-3-2016 at 21:24


Quote: Originally posted by Jstuyfzand  
I am planning on building a chloralkali cell to then make hydrochloric acid

Hello, I am involved in a similar project too. My results in combining H2 and Cl2 seem to be promising ( http://www.sciencemadness.org/talk/viewthread.php?tid=2154&a... ) but my progress in separating the cell (to keep NaOH out of the anode compartment) is almost zero.

Quote: Originally posted by Jstuyfzand  

Ps: I have tried the flower pot, did not went well.

May I ask what did go wrong? Do you think it is something that can be solved with a better approach or the flower pot idea is fundamentally wrong?

I was thinking also of a simple "salt bridge" using only filter paper to bridge the two compartments but I wonder also if this is capable from keeping the solutions unmixed. Also, Im afraid that the high resistance of that "bridge" may cut the electrolysis current to very low amounts.

I've seen online that there are some educational chloralkali cells available for shopping but I would like to keep it the simplest possible.
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Jstuyfzand
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[*] posted on 22-3-2016 at 08:11


Quote: Originally posted by experimenter_  


Quote: Originally posted by Jstuyfzand  

Ps: I have tried the flower pot, did not went well.

May I ask what did go wrong? Do you think it is something that can be solved with a better approach or the flower pot idea is fundamentally wrong?

I was thinking also of a simple "salt bridge" using only filter paper to bridge the two compartments but I wonder also if this is capable from keeping the solutions unmixed. Also, Im afraid that the high resistance of that "bridge" may cut the electrolysis current to very low amounts.

I've seen online that there are some educational chloralkali cells available for shopping but I would like to keep it the simplest possible.


The flower pot limited the current to extremely low current, and regarding the salt bridge, I have my doubts, the same as yours.

I wondered if a silicon kit mixed with a salt like NaOH could conduct the electricity and act like a membrane and transfer the ions.
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[*] posted on 22-3-2016 at 09:04


Quote: Originally posted by Jstuyfzand  

The flower pot limited the current to extremely low current, and regarding the salt bridge, I have my doubts, the same as yours.

I wondered if a silicon kit mixed with a salt like NaOH could conduct the electricity and act like a membrane and transfer the ions.

Hm, I see.

Did you mean silica gel bridge ( http://www.sciencemadness.org/talk/viewthread.php?tid=20816#... ) instead of silicon kit? (I don't know what silicon kit is)
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Jstuyfzand
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[*] posted on 22-3-2016 at 10:20


Quote: Originally posted by experimenter_  
Quote: Originally posted by Jstuyfzand  

The flower pot limited the current to extremely low current, and regarding the salt bridge, I have my doubts, the same as yours.

I wondered if a silicon kit mixed with a salt like NaOH could conduct the electricity and act like a membrane and transfer the ions.

Hm, I see.

Did you mean silica gel bridge ( http://www.sciencemadness.org/talk/viewthread.php?tid=20816#... ) instead of silicon kit? (I don't know what silicon kit is)


I do yes, but I just realized NaOH dissolves the gell, damnit, I am just going to try densely packed filter paper with NaOH
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[*] posted on 22-3-2016 at 12:05


Quote: Originally posted by Jstuyfzand  

I do yes, but I just realized NaOH dissolves the gell, damnit, I am just going to try densely packed filter paper with NaOH

I 've just tried filter paper with NaCl. In the anode compartment I put a steel needle. The anolyte became green very quickly. However, after 2 hours of electrolysis at 60mA, there was no green color in the catholyte, neither on the "bridge" paper! I think also that the bridge can carry more current than 60mA easily. It seems promising...
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[*] posted on 22-3-2016 at 13:23


Did you guys ever think about using agarose for the salt bridge? After solidifying it is practically insoluble, and 3% gel makes a really sturdy gel. It practically conducts the same amount of current as the solution you prepared it in would normally do.

In bigger (250gramish) amounts the really pure high quality stuff is about one euro per gram, but at 3% that would last you a life time.

It is even remold-able after melting at 100 degrees.

Ps. I believe you can also find it at an vegan alternative for gelatine, I don't know about the purity of that stuff, but as a role of the tumb; If it is white it is pure.

[Edited on 22-3-2016 by Tsjerk]
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Jstuyfzand
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[*] posted on 23-3-2016 at 13:53


Quote: Originally posted by Tsjerk  
Did you guys ever think about using agarose for the salt bridge? After solidifying it is practically insoluble, and 3% gel makes a really sturdy gel. It practically conducts the same amount of current as the solution you prepared it in would normally do.

In bigger (250gramish) amounts the really pure high quality stuff is about one euro per gram, but at 3% that would last you a life time.

It is even remold-able after melting at 100 degrees.

Ps. I believe you can also find it at an vegan alternative for gelatine, I don't know about the purity of that stuff, but as a role of the tumb; If it is white it is pure.

[Edited on 22-3-2016 by Tsjerk]


I will look into both, sounds promising, I assume you just mix in some electrolyte into the gelatin? Going to look at it now!
1€ a gram sounds expensive, and I try to keep the costs zero, I'm still a kid :D
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[*] posted on 23-3-2016 at 13:59


This is great, I read the wiki page on a gelatin (vegan) called agar and it is even mentioned as an ootion for a salt bridge.
And it is cheap too! Just mix it with an electrolyte, I will have a lroject this weekend. ill keep you guys updated.
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[*] posted on 23-3-2016 at 15:02


Yes, it also called agar or ''agar agar'', the cheap stuff is usually brownish and a bit less pure, but for a first try and depending on what you want to make it is probably fine.

About the price; don't forget you only need 2-3%, so a couple of grams will already make you 100ml of the gel.

To make it you make a suspension of it in your electrolyte of choice and heat it to 100 degrees while stirring, hold it against light to check if it completely dissolved, this usually takes a couple of minutes. When it cools down it solidifies, poor it in a watertight mold that can stand 100 degrees before it does.

You can let the solution cool down to about 50 to 60 degrees before it solidifies, when you want to melt it again you have to heat it to 100 degrees again.

Edit: To get any (charged) impurities out, you could just run your cell with plain electrolyte for multiple hours. This will "wash" any charged stuff out of the gel. Your electrodes have to be able to handle the voltage you run at for prolonged time though.


[Edited on 23-3-2016 by Tsjerk]
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[*] posted on 24-3-2016 at 13:35


Quote: Originally posted by Tsjerk  
Yes, it also called agar or ''agar agar'', the cheap stuff is usually brownish and a bit less pure, but for a first try and depending on what you want to make it is probably fine.

About the price; don't forget you only need 2-3%, so a couple of grams will already make you 100ml of the gel.

To make it you make a suspension of it in your electrolyte of choice and heat it to 100 degrees while stirring, hold it against light to check if it completely dissolved, this usually takes a couple of minutes. When it cools down it solidifies, poor it in a watertight mold that can stand 100 degrees before it does.

You can let the solution cool down to about 50 to 60 degrees before it solidifies, when you want to melt it again you have to heat it to 100 degrees again.

Edit: To get any (charged) impurities out, you could just run your cell with plain electrolyte for multiple hours. This will "wash" any charged stuff out of the gel. Your electrodes have to be able to handle the voltage you run at for prolonged time though.


[Edited on 23-3-2016 by Tsjerk]


For convenience, I will try the agar method, but if that fails
I will look into the other options!

Another question, Will SS electrodes be enough for Brine electrolysis or does the Anode need to be MMO, Platinum or carbon?
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[*] posted on 24-3-2016 at 20:49


Agar agar works but limit NaOH to about 3%.
Polypropylene 5 micro fabric, ie hepa vacuum bags, will
work as well. But with any diaphram method the chlorine side
must maintain osmotic pressure. SS will not work.
You need mmo, this is what its made for.
Ideal material is nafion and it is available but expensive.
Only a mercury cell can go to 50%.
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[*] posted on 26-3-2016 at 17:39


http://fuelcellstore.com/membranes/nafion

Surprisingly affordable. If I recall, this is the material of choice for commercial separate-cell electrolysis.




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[*] posted on 26-3-2016 at 20:01


The lower prices are 10 cm x 10 cm, the current density of membranes is fairly low compared to diphrams and mercury cells. So for a good current you need at least the 30 cm x 30 cm.
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[*] posted on 9-4-2016 at 16:52


I've made a cell using a "salt bridge" out of filter paper only. It works fine for the time being. The electrolysis current is not impeded too much by the bridge. It can carry more than 1A when voltage is elevated.

More details:
https://www.sciencemadness.org/whisper/viewthread.php?tid=65...
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[*] posted on 23-3-2017 at 07:27


Hy
I think divided cell will work better
For divided cell filter paper is not suitable
I made NaOH by divided cell
But i used saperator which is used in charging battery for anod and cathod sepration
It worked better
If u find any leackage use double
It is made of fiber and work great
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[*] posted on 23-3-2017 at 07:28


Hy
I think divided cell will work better
For divided cell filter paper is not suitable
I made NaOH by divided cell
But i used saperator which is used in charging battery for anod and cathod sepration
It worked better
If u find any leackage use double
It is made of fiber and work great
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XeonTheMGPony
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[*] posted on 23-3-2017 at 16:37


mercury bridge, made these and don this befor works great.
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