Electrolysis

[Externet]

Hi.
If seawater is exposed to an anode and cathode, the Cl- and Na+ ions attach to them, don't they?
As ions migrate and attach, the conductivity of the seawater should decrease, does it?
Why there is no electrolytic desalinization machines? Or are they?
Miguel

[Ron H]

I remember electrolyzing (table) salt water as a teenager (yeah, Dean, we actually had crude batteries back in those days). As I recall, hydrogen bubbles off one electrode, chlorine off the other, and sodium hydroxide precipitates.

[rshayes]

The charge of the ion is neutralized at the electrode by transferring an electron from the electrode to the ion in the case of Na+, or from the ion to the electrode in the case of Cl-. In some cases the atom is plated onto the electrode (as in copper, gold, or aluminum plating). In other cases, the atom reacts to form a molecule (as in Chlorine gas, Hydrogen gas, or Sodium metal). If there was no water present, electrolyzing NaCl gives Chlorine gas and metallic Sodium, which sinks to the bottom. If water is present, the Sodium would react with the water to form Sodium Hydroxide. This should remain in solution until the solution becomes saturated.<p>When water is present, there are several possible reactions. The water may be split into Hydrogen and Oxygen, which would escape as gas. Each of the reactions has a potential which will determine which one goes first. This is the basis for an analysis technique called Polarography. In the case of salt water, the water might be removed before the salt began hydrolyzing. The salt would precipitate, since it normally does not conduct electricity. If the salt was melted by raising the temperature, it could be split into Chlorine and Sodium.<p>[ May 02, 2004: Message edited by: stephen ]</p>

[perfectbite]

electrolytic desalinization machines<p>Long ago I was once told by a lab technician that the conductivity of water was a standard for testing the purity of water. Absolutely pure water, basically just H2O, doesn't conduct electricity. Stuff in the water does.<p>I am not sure that such an electrolytic desalination machine would not also (like a distilled water 'boiler') be a demineralizing machine too. The produced water would quench your thirst but, if it were used to any great extent, one's teeth would rot out very quickly.

[haklesup]

Cleaner water does not promote accelerated tooth decay or chemical erosion of tooth enamel.<p>The DI water may not taste as good as water with trace minerals but it will not hurt your teeth. <p>Unless you have an unusually clean mouth, water is contaminated with ions in your saliva as soon as it enters your mouth.

[josmith]

Too pure water will deplete your body of electrolytes and minerals. Purified water is made completely pure and then standardized by adding minerals.

[jwax]

Externet, there are electrolytic desalinization processes, but is a very expensive way to get the salt out. Reverse osmosis, de-ionization, molecular sieves are all effective to a degree, but also expensive. We find a cheap way to do it, and well, rich isn't the word for it! $$$$$$$$$$!

[techno]

Not sure but I think Nuke subs do this. This is how they get their oxygen but not sure if they also get water from this method or not. Recombine the Oxygen and Hydrogen since they have the power.<p>BTW pure water has a dielectric strength of 40Kv. I remember because I read it as 14 KV and built a spark gap switch with it- didn't work of course since only had 15 KV.
They use pure water in the high powered Cyclotrons and others for switches. Water is conductive like everything- just feed it enough!

[Chris Smith]

The reason it doesn’t work for making pure water is because the curve of efficiency drops as more and more of the minerals/elements are extracted. <p>They use the process commercially to produce chlorine and sodium products, but as the level drops, so does the efficiency of the electrodes.

[Clyde Crashkop]

You can get hydrogen gas and oxygen from electroysis for fuel. Together they are Brown's gas that will burn in a torch without any extra oxygen, or run an engine set up for propane. See OUPower.com for more info.