Electrolysis to reduce water's saltiness

[Phytochem]

Hi

I wonder if we can reduce the quantity of salt (mostly Cl^- and Ca²⁺) from water by electrolysis and still be safe to drink. I know that with inert electrods (not sure wich ones although) Cl^- would be trun into Cl_2(g) and I'm concerned by its toxicity even though it's going in the air. But I'm don't know what's going on about the Calcium: if it can be precipitated or if I can't get rid of it and will just need to adjust the pH.

Thanks

[EdEarl]

Electrolysis of water generates H2 and O2; thus, concentrating dissolved solids. See: https://phys.org/news/2018-02-efficient-sustainable-filter-salt-metal.html

[Sensei]

Result of electrolysis is release of Hydrogen gas mostly, and Oxygen gas (if there is used e.g. Gold or similar metal as positive electrode)..

So during electrolysis amount of water is decreased. While Na⁺ Ca²⁺ Cl^- and other heavy ions still remain in the same water..

 

You could boil water, condense vapors, and receive distilled water.

It can be done quite efficiently, especially in tropics (without additional power source from burning oil, gas or coal). Concentrate light from the Sun, using mirrors on hermetic container with water, with output going to Graham condenser. From time to time fill container with new amount of water. Output will be pretty good distilled water.

 

Alternative methods of cleaning dirty water are reverse osmosis:

https://en.wikipedia.org/wiki/Reverse_osmosis

and active coal.

 

Edited February 12, 2018 by Sensei

[swansont]

You create hydrogen and oxygen only if the voltage is high enough to dissociate the water. If you limit the voltage, that won't happen.

You can use electrodes to remove ions

https://phys.org/news/2012-06-wires-salt-freshwater.html

[Phytochem]

20 hours ago, Sensei said:

You could boil water, condense vapors, and receive distilled water.

That is good to know but actually I'm working on a product containing water meant to be drank and I'm concerned about reducing its saltiness without degrading the container (made from calcium alginate, allowing ions to go through), that's why I thought about electrolysis.

I'll keep on working on it, see if indeed I can avoid the hydrolysis and still get the electrolysis to be efficient.

Thank you all for your answers

[John Cuthber]

"I wonder if we can reduce the quantity of salt (mostly Cl^- and Ca²⁺) from water by electrolysis and still be safe to drink. "

Yes

https://en.wikipedia.org/wiki/Electrodialysis

 

[fredreload]

My idea is to use a graphene filter, they said it's too slow, but you can increase the surface yield

[Phytochem]

Yes actually I end up finding this company: http://www.cdi-electrosorption.org/

They are using this method to remove saltiness with a very low energy cost and no impact to the environment