# What is the best way to separate ions in water?

1. Jul 28, 2013

### sr241

What is the best way to separate ions in water? for example separating Na+ and Cl- ions from a sodium chloride water solution ( water is a ionizing solvent). is using magnets a best way or is electromagnets a best way or using Lorentz force(combination of electrical and magnetic force) a best way.

How to calculate energy required to separate these ions, is there any chance this energy would be less than enthalpy of formation of sodium chloride?

2. Jul 28, 2013

### Staff: Mentor

How would you separate ions with magnets?

Electrolysis looks like an obvious solution.

What do you plan to do?

3. Jul 28, 2013

### epenguin

I suspect someone with much understanding of chemistry would not use the term 'separate the ions' in solution which basically you cannot do.

You can electrolyse a NaCl solution with slightly complicated results, products are chlorine gas Cl2 hydrogen H2 and NaOH. This is an industrial process you can fnd in school chemistry books, I have a vague uncertain memory of seeing it done in a laboratory apparatus at school.

You can in solution use ion-exchange resins to exchange the ions for others, e.g. the Na+ by K+or H+ or the Cl- by OH- or by SO42- (in a 1:2 ratio obviously). Probably done in your school if you are in one to prepare 'deionised water', and in dishwashers etc. (to get rid of Ca2+ particularly.

4. Jul 28, 2013

### sr241

What do you plan to do?

Magnets poles attract +vely charged ions and -vely charged ions separately. if we flow the ionic solution through a pipe and place a "C" magnet over it and split the +ve and -ve ions into separate vessels; what is the energy requires to separate these ions how to calculate it.

5. Jul 29, 2013

### Staff: Mentor

No they do not. Magnetic poles would attract magnetic charges, but those do not exist (or have not been found yet).

Independent of the mechanism, you need at least the amount of energy you can get if you mix them again afterwards.

6. Jul 29, 2013

### sr241

Magnets can propel ions (Charged particles) that's why Ion thrusters in rocket science works.
Large hadron collider works using this principle they can accelerate proton (H+ ion).

What is the known best way to separate ions in solution?

7. Jul 29, 2013

### Staff: Mentor

Static magnets can change their direction, but not their velocity (in the frame of the magnets). Ion drives use electric fields to accelerate the ions.

Again, magnets are just used to keep the particles in the circular path. Acceleration is done via electric fields.

Did you see my suggestion of electrolysis?

Last edited: Jul 29, 2013
8. Jul 29, 2013

### sr241

Can we flow ionic solution (NaCl water solution) through a pipe and put a "C" magnet over it and split th flow of +ve ions and -ve ions into two separate vessels. does this idea work? has any one tried this? can this idea called a novel one? is this idea is of any use to practical problems?

9. Jul 30, 2013

### Staff: Mentor

You can get a small displacement, but that is quickly cancelled by the electric field that forms. If you connect the sides electrically, it might be possible to separate some ions. I doubt that this process has a reasonable efficiency.

10. Jul 30, 2013

### sr241

since magnets only change directions and does no work I thought I made a free energy device to split ions in solution

11. Jul 31, 2013

### hilbert2

This sounds like you're asking how to force Na+ and Cl- ions apart from each other so you could have "1 mole of positive ions in one jar and 1 mole of negative ions in another jar". That is NOT possible, the electromagnetic interaction is just too strong. If you know Coulomb's law, you could calculate as an exercise the force that one mole of positive charges and one mole of negative charges would exert on each other even if the distance between them was 10 kilometers. Or estimate by dimensional analysis the pressure that would be needed to confine 1 mole of free Na+ ions in a volume of 1 dm3.

What is a "free energy device"? I hope you don't mean some kind of perpetual motion machine...

12. Jul 31, 2013

### Staff: Mentor

That is not possible, and it is pointless to try - in addition, it violates the forum rules to discuss that.

Your deflected ions would slow down due to the electrical potential that forms, and slow down the water flow.

13. Jul 31, 2013

### sr241

If we use an inverted "Y" tube with short hands at the end of flow tube and place "C" shaped magnet at the junction of "Y" tube. will this work?

I am some what sure that a simple device like this will not be enough to tweak a well established law like conservation of energy.

14. Aug 1, 2013

### Staff: Mentor

The complexity is completely irrelevant. You can show (with mathematics) that the known laws of physics conserve energy. It is pointless to try to violate mathematics. You would need some violation of the known laws of physics, and this can be found with a real experiment only. You do not have this (in particular: you do not have this in a peer-reviewed journal), so this thread cannot lead to anything interesting. I closed it.