Sciencemadness Discussion Board

Trying to Build First Electrolytic Cell: Diaphragm/Ion Permeable Membrane?

CwisGons - 21-6-2022 at 21:14

Hello everyone. I want to try to start a big project. Eventually, I wanna build an electrolytic cell that makes sodium hydroxide, bleach, and maybe even hydrogen chloride, possibly purely powered by a bicycle.
But first baby steps,
I wanna begin making the cell by first designing the diaphragm/ion-permeable membrane.
I was inspired by both these videos:

I wanna make the design mostly based on this:
https://www.youtube.com/watch?v=iZH5fB0iM7U

However, I also wanna make/add the membranes shown off in this video, since I think I can make these fairly cheaply.
https://www.youtube.com/watch?v=tiMt4tIced8

First, he mentioned that some cleaning products can be used to make the dechlorination solvent, even shampoo. Can I use this shampoo?

https://www.walmart.com/ip/2-Silkience-Salon-Series-Advanced...

I chose this shampoo because it seemed to contain the highest amount of quaternary ammonium salts due to containing both Cocamidopropyl betaine and polyquaternium-7, and was only a dollar where I found it. However, this product appears to have no SDS. How do I know how much to add to the solution?

Also, a more important question is how I construct the membrane/diaphragm, or if it would even work? Essentially, I would sandwich the bottom of a clay pot between two of these membranes, and stick them together using vegetarian gelatin or agar agar.
Or maybe perhaps I stick them using the citrate/PVA mixture, and bake them together?

Would this work? Any advice or tips?





mysteriusbhoice - 22-6-2022 at 05:31

the membrane relies on an ion exchange resin containing functional groups that bind to cation in solution sodium potassium hydrogen ions etc.
the citric acid + PVA membrane needs to be baked at 160C for 35 mins in order for the citric acid to crosslink esterify the PVA chains where the unlinked carboxylic acid acts as the ion exchange group.
when electricity flows through the unit is when it allows for ions to be transferred against the concentration gradient.

Porous pots work like clay and agar work on osmosis and also this allows for a delay on the transfer of ions across a concentration gradient. The electricity flow allows for ions to be transferred across the 2 chambers to whichever electrode they are attracted to.

To construct a membrane cell you need a substrate for the membrane which would either be fiber glass or cotton cloth. The PVC resin is a binder/primer which when dechlorinated create a reactive surface to allow for crosslinking between partially dechlorinated PVC and PVA chains via citric acid.
The PVC itself can act as a porous barrier without ion exchange properties and you can actually just use it as is or partially dechlorinate it to increase porosity without having to bake layers of PVA ester ion exchange resin.

NaOH works better using an ion exchange resin but it also works with porous barriers.
bleach cannot be made using ion exchange membranes as it will just produce Cl2 and NaOH and when bleach is produced it means the membrane is destroyed which happens when NaOH reaches a high concentration.

Try the use of ionomer Cement which is better than claypot and has both porous properties and ion exchange resin properties.
2 kinds of ionomer cement are possible to make
1. CaSO4 based ionomer cement which can be used for chloroalkali process and sodium hydroxide (below 10%) but not for preparation of acid like H2SO4 from soluble sulfates.
2. Ion exchange resin impregnated concrete which can be used for everything!!.

This video shows the process.
https://www.youtube.com/watch?v=crAlzaicWFM

Corrosive Joeseph - 22-6-2022 at 06:27

Lead acid batteries contain the membrane you are looking for.....
Quote:

In case the electrodes come into contact with each other through physical movement of the battery or through changes in thickness of the electrodes, an electrically insulating, but chemically permeable membrane separates the two electrodes. This membrane also prevents electrical shorting through the electrolyte


https://www.pveducation.org/pvcdrom/lead-acid-batteries/oper...



/CJ

Hexabromobenzene - 22-6-2022 at 17:10

I want to make a membrane from sulfonated polystyrene from a used water filter. I reactivated it with hydrochloric acid. I'm thinking of dissolving it in dichloromethane and soaking the polypropylene fabric from the bags(meltblown). This fabric can also be used to secure the membrane to the container like a rope or collar. Also for her protection.

I also have porous polypropylene membranes from car batteries. 1 car battery contains 32 sheets approximately 25cm x 15cm. Before use, you must wash it with a thought of lead oxide. The membrane can also be removed from a lithium-ion battery, but often used batteries contain a damaged membrane or with clogged pores. It is also thinner and has less mechanical strength.

I will probably test both membranes, but the porous membrane seems to be more reliable since it cannot be destroyed by chemical

[Edited on 23-6-2022 by Hexabromobenzene]

[Edited on 23-6-2022 by Hexabromobenzene]

mysteriusbhoice - 25-6-2022 at 05:55

Quote: Originally posted by Hexabromobenzene  
I want to make a membrane from sulfonated polystyrene from a used water filter. I reactivated it with hydrochloric acid. I'm thinking of dissolving it in dichloromethane and soaking the polypropylene fabric from the bags(meltblown). This fabric can also be used to secure the membrane to the container like a rope or collar. Also for her protection.

I also have porous polypropylene membranes from car batteries. 1 car battery contains 32 sheets approximately 25cm x 15cm. Before use, you must wash it with a thought of lead oxide. The membrane can also be removed from a lithium-ion battery, but often used batteries contain a damaged membrane or with clogged pores. It is also thinner and has less mechanical strength.

I will probably test both membranes, but the porous membrane seems to be more reliable since it cannot be destroyed by chemical

[Edited on 23-6-2022 by Hexabromobenzene]

you can also use fiberglass cloth as a substrate which should be very chemically resistant.

Hexabromobenzene - 16-8-2022 at 12:25

I took out an ion exchange resin from an old water filter. These are transparent orange balls. They are made from a sulfonated polystyrene-dvinylbenzene copolymer. The ion exchange resin was treated with hydrochloric acid to give the acidic form. Then it was dried

The obtained dry round granules are insoluble in organic solvents. They are insoluble in acetone and dichloromethane. To obtain a diaphragm, it is necessary to apply the resin to a porous carrier, but the polymer is not soluble in anything. What should I do with this substance? I have dismantled many used water filters and I have about 4 kg of this ion exchange resin.
How to make a diaphragm out of it? How to dissolve it?

mysteriusbhoice - 17-8-2022 at 05:02

Quote: Originally posted by Hexabromobenzene  
I took out an ion exchange resin from an old water filter. These are transparent orange balls. They are made from a sulfonated polystyrene-dvinylbenzene copolymer. The ion exchange resin was treated with hydrochloric acid to give the acidic form. Then it was dried

The obtained dry round granules are insoluble in organic solvents. They are insoluble in acetone and dichloromethane. To obtain a diaphragm, it is necessary to apply the resin to a porous carrier, but the polymer is not soluble in anything. What should I do with this substance? I have dismantled many used water filters and I have about 4 kg of this ion exchange resin.
How to make a diaphragm out of it? How to dissolve it?


You can imbed them into cement like in this video.
https://www.youtube.com/watch?v=crAlzaicWFM
iONOMER CEMENT.

Organikum - 17-8-2022 at 07:55

Gore Tex makes great cell dividers/membranes for electrochemistry, if it is a good choice in this application I cannot say, but it can be bought at tolerable prices or just ripped out of discarded higher end functional winter jackets and similar. When it says big "Gore Tex" on the label then it might be even true. Not always though. ;)


/ORG

Mateo_swe - 4-10-2022 at 11:31

If you are not doing this for the satisfaction of doing it yourself you can just buy a professional membrane.
There is a lot of variants to choose from and its not always as expensive as you may think.
Look at Fumatech or https://www.fuelcellstore.com/ or similar that sells membranes.
I bought a membrane from Fumatech in their webshop but i cant find the webshop anymore, mabe they just sells via fuelcellstore these days.
It was not particular expensive.

If you want to do it yourself you can make a clay membrane if you have access to a oven for hardening/burning the clay.
Its just like the orange flower pots without the hole in the bottom, or if you can find such a pot without the hole.
If you go for clay you must start with a pure clay base and not a ceramic clay as the ceramic variant doesnt have open pores after the hardening/burning in the oven.
Ask in the clay store what is clay and what is ceramic based clays.
Also you can put glaze on the top rim where the pot is above the liquid in your cell, this seals the pores in that section and prevents that the liquids creep over the rim.

[Edited on 2022-10-4 by Mateo_swe]

[Edited on 2022-10-4 by Mateo_swe]

Hexabromobenzene - 1-3-2023 at 03:18

Is it possible to make a diphragm from an ordinary plastic bag? The lithium of ion batteries uses porous polypropylene, but it is difficult to find a separator of a suitable size and not contaminated with the material from the cathode and anode. The plastic bag is probably poorly conducted, but this can be compensated by a large area

mysteriusbhoice - 4-3-2023 at 11:43

Quote: Originally posted by Hexabromobenzene  
Is it possible to make a diphragm from an ordinary plastic bag? The lithium of ion batteries uses porous polypropylene, but it is difficult to find a separator of a suitable size and not contaminated with the material from the cathode and anode. The plastic bag is probably poorly conducted, but this can be compensated by a large area


no but you can make porous PVC membranes by adding PVC glue to cleaning cloth substrate and soaking in water then drying.
If you need ion exchange properties then you can use a mix of PVA and citric acid and baking it at 160C for 30 mins and washing unreacted and repeating up to 4x.

Hexabromobenzene - 6-3-2023 at 12:06

I dont have PVC glue and solvent for PVC. I can make polystyrene glu

mysteriusbhoice - 8-3-2023 at 00:14

Quote: Originally posted by Hexabromobenzene  
I dont have PVC glue and solvent for PVC. I can make polystyrene glu


that can be put on fiberglass substrate and treated with 98% sulfuric at 80C and it will form polystyrene sulfonate membranes.

Mateo_swe - 8-3-2023 at 13:04

The absolute easiest membrane is a clay pot, preferably without the hole in the bottom.
It can have problems with liquids creeping over the rim but it can be avoided by applying a glaze on the top part.
One can probably use other DIY alternatives to clay glaze.

Edit: It must be an unglazed clay pot as a glazed one dont let anything through.
The common orange clay flower pots works.

[Edited on 2023-3-8 by Mateo_swe]

DXFlatline - 11-11-2023 at 11:51

Use the search term "porous cup" for a clay pot specifically made for voltaic cells. They're easy to find and cheap. Amazon sells them for $10