(published on 04/12/07)
Yes, it is possible to separate salt from water, but only if you are careful. As you might already know, a salt water solution lowers the freezing point of water because the salt ions get in the way of the water molecules as they try to freeze by sticking together. However, if you lower the temperature enough, you will get some water to freeze, expelling the salt that would be in that water to the rest of the solution. This will make the rest of the water saltier. Now the water does not form perfect ice crystals, so there could be a bit of salt in some of the spaces in the ice. However, if you let the water freeze slowly, this will give the salt more time to get expelled from the ice. If you want to make sure that all the salt is out of the ice, you should remove the ice, let it melt in another container and repeat again. I you want to read more, look here.
(published on 02/14/13)