Separating Na+ and Cl- in saline

Hello!

Is it possible to have a tank of saline where one side has more Na+ than Cl-, and the other side has more Cl- than Na+?

I'm trying to figure out how to do do this, maybe with two similar metals with a circuit charge through them - maybe with a north/south magnet?





No big deal, but I'm also just curious if anyone has experience with nerve axon experiments in saline

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. Thanks for your insight!

 

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Hang on, are you trying to do this with cells or with just a tank of water? If cells yes its easerly possible because the Na + channels are highly selective, when triggered they ONLY alow Na in, Cl comes in through a different channel and is activly kept out because it lowers the resting potential meaning that more is needed to trigger the cell (alchole works by ataching to tjese channels)

If just water its also possible with a current which will have a possitive and negitive side

 

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I was hoping to do this in a tank of water, and freeze it so the na+ and cl- won't come back together.

So essentially, it would be a block of ice where the left side of the ice will have more na+ than cl-, and the right side will have more cl- than na+.

I know I won't be able to do experiments in this, but oh well, I want to separate these!

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This how they make bleach Chlorine go to the Anode and sodium should go to the cathode but the discharge in the cathode will be Hydrogen das

 

Electrolysis?
This is a new method I recall that has to do with desalination and removing all particles and salt from water, however maybe something similar could suit your purposes. That is the only reason I mentioning here.

http://www.cleantechblog.com/2009/11/low-cost-desalination-saltworks.html

http://planetgreen.discovery.com/tech-transport/water-desalination-portable-solar.html

It is not my field, so I apologize if these articles are not of assistance, but thermionics seemed like a idea that might be handy here.

 

A word of warning about a potential hazard. In aqueous solutions (particularly alkaline and at elevated temperature) a couple of unexpected reactions can occur when electrolizing halogen compounds, ie chlorine, bromine, and iodine salts. The first is spontaneous oxidation of the halogen ion, for example Cl- + O -> ClO- . The second is called disproportionation. In the case of chlorine 3 ClO- -> ClO3- + Cl2 + 2e- . To make a long story short you can accidentally make chlorate, a powerful oxidizer. Potasium chlorate is the oxigen source for the space shuttle solid rocket boosters. Not a good thing. Be careful.

 

To convince yourself this is very simple, get a battery, two pieces of copper wire, a glass of water, and some salt. Or in place of a battery you can use a battery charger.

Put a few spoons of salt in the water. Stick the wires in. Attach them to the battery. In a minute or so you will see bubbles. You are smelling chlorine evolving as gas from one electrode. Sodium metal will settle on the other side, and the water will look dirty.

At this point your energy input is low, so you hazards are low.

You can collect the sodium with a coffee filter. The chlorine won't easily solidify - not sure you want that - but can be crystallized in some other compound for storage. It Depends on what you're after.

So this is electrolysis.

To go further, you can capture the chlorine gas in an inverted beaker, or devise a way to pump into a tank. At this level you will want to clear it with police and fire officials, get any permits etc., because you are starting to manufacture a hazardous material, with toxic, flammable and explosive risks. There are statutes to protect public safety, so you would need a specialist to help you do it legally.

At that point, you can get away from water and use molten salt. It's a widely used process, you can look it up.

 

After rereading you original question, I see you are wanting the separation in one vessel. Divide the vessel with a wall. Install one electrode on each side of the wall. Run them through the tank outer wall, insulated and pressure sealed. Use a semipermeable isolator between the two partitions. Ions will pass through and separate. It's a little more trouble but maybe this is what you were wanting to do.

Be careful and good luck.

 

Thanks for the heads up on the side products made besides hydrogen and oxygen gas.

I did this exact thing last night, and put the saline + battery + electrodes in a freezer overnight. I used a 1.5v AA, thinking that would be good enough to see if it would work, and the battery would exhaust it's capacity after the water froze, and wouldn't perform electrolysis, since electrolysis is still possible in ice, to the best of my knowledge.

Thanks allot for this tip... I didn't think about this. Just curious, what's the purpose of the semipermeable membrane?

I'll report back here.

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Safety question

I'm planning on (again) performing electrolysis in saline while in a freezer, in an attempt to freeze the excess Na+ and excess Cl- regions.

Once the freezing is complete, and the air has been ventilated properly, would it be safe to handle the brick of polarized saline like any other piece of ice? I'd like to observe it while it melts, recording the voltage difference between the two regions.

Thanks for your help guys. I'll post a photo of what the solution looks like.

 

I wonder how will you produce sodium metal in an aqueous system ?
It seams you missed chemistry or perhaps you forgot

 

No I didn't mean pure sodium. Just wanted to get the point across about a simple way to get started.