[quote=dvice]
As the world's population continues to grow, fresh water is becoming one of the most valuable (and contested) resources on the planet. Whether it's for drinking, agriculture, or keeping our armpits clean, we need more of it, and we now may be able to make that happen with little more than a fancy battery.
Trying to get fresh water out of the ocean is not a new idea, and we've been pulling it off successfully for a long using techniques like evaporation and reverse osmosis. It's hard work, though, which means a lot of energy is required, which also means a lot of money is required, to the point where California has been considering the importation of fresh water in bulk from Canada using converted oil tankers.
Until the oil tankers thing gets going, it might be worth checking out a new technique that only requires a battery. Last year, some researchers at Stanford University discovered that you could generate an electrical current by pumping salty water followed by less salty water through an electrochemical cell. That's neat, but if you run the same experiment backwards, it turns out that adding electricity to an electrochemical cell with salt water running through it will make that water less salty.
Here's how the system works: you put together an electrochemical cell with two electrodes, add seawater to it, and then turn on an electric current. The current sucks chlorine ions onto an electrode made of silver and sodium ions onto a an electrode made from manganese oxide nanorods. Once the ions have been removed, the fresh(er) water is taken out of the battery, and more salt water is put in. Then, those trapped ions are released into that water, you get rid of it as a waste product, and start over again. Since no heat or pressure is involved, it's very efficient, and it's also much cheaper and easier to construct.
There's still plenty of work to be done before a system like this will be able to produce water that's suitable for drinking. At the moment, one pass through the battery removes 50% of the salt from seawater, but to call something "fresh," it needs to be 98% salt-free. Sulfates still need to be taken care of, and there are questions about how reliable the system will be, but this is all stuff that's to be expected in a brand-new technology that's just barely out of the lab.[/quote]
[url]http://dvice.com/archives/2012/02/battery-turns-s.php[/url]
That is a pretty kool piece of tech.
It would also help ship wreck survivors on the sea for a much longer time improving survivability chances.
I was hoping it would generate electricity and remove the salt. A bit too much too ask i suppose.
[QUOTE=sami-pso;35966074]I was hoping it would generate electricity and remove the salt. A bit too much too ask i suppose.[/QUOTE]
I know right?
I am still waiting for the car which goes for free and every few kilometers you can pour off some extra gasoline it produces on the way.
Wouldn't the current electrolyse the water molecules themselves?
If you use wave power then it could be pretty much self-supplied with electricity.
Free water :D
So what happens to the sodium ions left over from the sodium chloride?
I'd rather drink sodium chloride than sodium hydroxide, just saying.
This isn't new. Its fucking Electrolysis and I'm sure its been around since the 1800s.
So it doesn't quite turn saltwater into freshwater yet; more like saltwater to brackish water at the moment.
Nonetheless it's a good start for an advanced application of electrolysis; it just needs to increase efficiency so that salinity is reduced to at least 2% or lower, as well as taking care of any potential toxicity.
Also, is there any kinda method by which clouds can be attracted towards a very VERY tall antenna? If there is then a theoretical Rain Tower could prove handy for bringing rains to drier lands. When autumn comes, California can HAVE our rainclouds; we've enough of them as it is.
[QUOTE=ironman17;35967605]So it doesn't quite turn saltwater into freshwater yet; more like saltwater to brackish water at the moment.
Nonetheless it's a good start for an advanced application of electrolysis; it just needs to increase efficiency so that salinity is reduced to at least 2% or lower, as well as taking care of any potential toxicity.
[/QUOTE]
If they use this electrical technology to lessen the amount of salt, would it make it easier (and cost less power/money) to put the same water through a desalination plant?
[QUOTE=JgcxCub;35966383]Wouldn't the current electrolyse the water molecules themselves?[/QUOTE]
Yeah. I'm thinking they are separating the O2 and H2 and then recombining them in another chamber or something. The oxidation and reduction potential on NaCl is far too high to be separated in water.
[QUOTE=ironman17;35967605]So it doesn't quite turn saltwater into freshwater yet; more like saltwater to brackish water at the moment.
Nonetheless it's a good start for an advanced application of electrolysis; it just needs to increase efficiency so that salinity is reduced to at least 2% or lower, as well as taking care of any potential toxicity.
Also, is there any kinda method by which clouds can be attracted towards a very VERY tall antenna? If there is then a theoretical Rain Tower could prove handy for bringing rains to drier lands. When autumn comes, California can HAVE our rainclouds; we've enough of them as it is.[/QUOTE]
There is a way to make rain drop before it reaches a certain place, but this causes a lot of issues in the ecosystem... in the long run its worse
In other words- you have to take away rain from someplace else in order to gain that rain in drier lands...
[QUOTE=thegrb93;35967681]Yeah. I'm thinking they are separating the O2 and H2 and then recombining them in another chamber or something. The oxidation and reduction potential on NaCl is far too high to be separated in water.[/QUOTE]
It's not, you just need a special membrane so you don't end up remaking NaCl and NaClO through the salt bridge.
[QUOTE=Kendra;35967755]It's not, you just need a special membrane so you don't end up remaking NaCl and NaClO through the salt bridge.[/QUOTE]
In electrolysis, the reduction potential of chlorine is 1.36 and the reduction potential of water is 1.23. The reaction with the lowest potential is carried out first, so you'll hydrolysize all of the water before any NaCl is electrolized, and it would be a solid by then.
So, it's pretty much this thing with salt water instead of metallic ions?
[img]http://www.shodor.org/unchem/advanced/redox/ex9.gif[/img]
[QUOTE=Angus725;35967868]So, it's pretty much this thing with salt water instead of metallic ions?
[img]http://www.shodor.org/unchem/advanced/redox/ex9.gif[/img][/QUOTE]
Close, but that is a battery.
[url]http://en.wikipedia.org/wiki/File:Electrolysis_Apparatus.png[/url]
or in this case.
[url]http://www.instructables.com/image/F4A54HNF5R8MQ53/Electrolysis-of-Water-An-Explanation.jpg[/url]
Why is this in the news, this is a science experiment that I did when I was 8 years old, and probably about 12 times since. Please note that on one of the electrodes [URL="http://en.wikipedia.org/wiki/Chlorine#World_War_I"]chlorine gas[/URL] forms as well, so large scale operations are actually quite dangerous (or at least I'd imagine so, don't know what you're going to do with the chlorine)
[QUOTE=thegrb93;35967850]In electrolysis, the reduction potential of chlorine is 1.36 and the reduction potential of water is 1.23. The reaction with the lowest potential is carried out first, so you'll hydrolysize all of the water before any NaCl is electrolized, and it would be a solid by then.[/QUOTE]
Take a 9V battery, stick some wire on it, put it around some pencil rods, stick it in a saturated solution of brine, your solution will start turning yellow from the chlorine.
Physical evidence contradicts.
[QUOTE=Kendra;35967987]Take a 9V battery, stick some wire on it, put it around some pencil rods, stick it in a saturated solution of brine, your solution will start turning yellow from the chlorine.
Physical evidence contradicts.[/QUOTE]
That yellow is probably from the wire being oxidized, but I'll look it up.
This thread pretty much rules out chlorine making the solution yellow.
[url]http://www.physicsforums.com/showthread.php?t=476708[/url]
Does this mean they take the salt and refine it for commercial use as well?
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