Water + Salt + Energy = Clean! 374
codesmith.ca writes "CTV News is reporting about a device built at the Russian Institute for Medical Engineering that can convert standard water and salt into an antimicrobial solution. Apparently it's works on almost anything (virii, bacteria, cysts...) and it's safe for human consumption to boot. I can't find a site for the institute, but there are articles around. This one is fairly detailed, but hard to reach. Here's the Google cache. Here's one about a paper shows it's not exactly super-new technology." Any chemist care to comment on what sounds to be too good to be true?
Comment removed (Score:3, Informative)
Just a Swimming-Pool Chlorine Generator? (Score:4, Informative)
A more balanced description (Score:5, Informative)
http://www.fwr.org/wrcsa/832100.htm
It's plain simple ... (Score:5, Informative)
Freshman chemistry tells you:
NaCl -> Na+ + Cl-
H2O -> H+ + HO- (actually H3O+ instead of H+ but that's details)
Then, you add some electricity and you get:
At cathode (- electrode), H+ -> H2 (bubbles out) which means a lot of Na+ and HO- are left floating around - thus, per Google cached article in the original post: "The catholyte is a powerful alkaline solution used for [...]" -- not surprising at all, as you can see
Then, at anode (+ electrode) you've got HO- and Cl-
Cl2 + NaOH -> NaCl + NaClO
Now what does the article say?
Damn that highschool chem
END-OF-CHEM-LESSON
Re:Just a Swimming-Pool Chlorine Generator? (Score:3, Informative)
http://www.watermaid.com.au
for one. There are quite a few others, too. Just throw "salt water chlorination" into google.
Re:Just a Swimming-Pool Chlorine Generator? (Score:2, Informative)
Science News had an article on this... (Score:5, Informative)
NaCl + 2H20 + electricity -> Na + Cl + 2H2 + O2
Rather, you get a hypochlorous acid ion, an a sodium hydroxide ion. In effect, the reverse of mixing hypochlorous acid and lye.
However, you get it in VERY dilute quantities, nowhere near what you'd need to damage human skin. But if you are an itty bitty microbe, the oxidizing effect is deadly.
Really, this is just a "bleach on demand" sort of thing.
High School Chemistry (Score:4, Informative)
Oh the pain! The people complaining about the state of science education in the US are RIGHT!!
Electrolysis of salt solution produces a solution of sodium hypochlorite, similar to Clorox bleach. Nothing wrong with that, this is a GREAT disinfectant. But new technology? I DON'T THINK SO. We have been chlorinating water supplies since 1908 or so.
Some technological historians believe that the addition of chlorine to drinking water is the primary reason for increased life expectancies in the 20th century, and claim that this one innovation has done more to prevent disease than the rest of modern medicine combined.
Here are the reactions:
anode: 2Cl- = Cl2(aq) + 2e-
cathode: 2e- + 2Na+ + 2H20 = H2(g) + 2NaOH
2NaOH + Cl2 = 2NaOCl + 2H+
To stabilize the NaOCl it is best to add a bit extra NaOH. (See LeChatlier).
You can use the H2 to power your laptop. (See fuel cells.)
Re:This is SO snake-oil (Score:3, Informative)
OIL RIG
Oxidation is Loss (of electron) Reduction Is Gain (of electron)
Anything atom or molecule that gives up an electron in a reaction is an oxidizer. Anything that gains or takes an electron is a reducer/reducing agent. They're paired reactions.
Oxygen can be either a reducer or an oxidizer, depending on the reaction and its starting oxidation state.
Thank goodness for B. Perens and the post right above his debunking this 'breakthrough' chemistry as high school chemistry lab exercises.
I was beginning to worry that I would have to do it myself, and they did it much better.
Marcus
Re:This is SO snake-oil (Score:2, Informative)
Dammit.
Sodium (Na) and the sodium ion (Na+) are not the same thing. Salt is an ionic compound; when I dissolve it in water, I get water and a whole bunch of dissolved Na+ and Cl-. They're ions, which behave chemically in a fashion distinct from the full atom, which is why the glass of salt water doesn't explode and why I don't oxidize my esophagus if I drink it.
Re:This is SO snake-oil (Score:4, Informative)
Hydrogen a highly-reactive gas, thus antibiotic.
Oxygen, an oxidizer (duh), oxidation is about the most commonly used method of disinfection.
Sodium, a highly reactive chemical and thus disinfectant.
Chlorine, a superoxidizer (see above).
Actually, you just get the most easily reduced/oxidized species coming out. This means chlorine and hydrogen. The water stays water, and the sodium displaces the removed hydrogen to form sodium hydroxide. So, your saltwater turns into oven cleaner, which is not safe to drink, and you get chlorine gas bubbling off, which works quite well as a disinfectant (and is already used).
I wouldn't worry about the hydrogen. It's not terribly reactive, contrary to what you appear to have heard. It does burn, but you won't have enough present to worry about.
If they're using this for disinfecting, what's probably happening is that they're producing sodium chlorate. This can be formed instead of chlorine gas if your electrodes are close enough together that the ion species can mix. Sodium chlorate is a strong oxidizing agent; in weak solutions, it should be a decent disinfectant. I *really* wouldn't drink it, though (it's poisonous in significant amounts).
Contrary to what the article says, I seriously doubt you could mist a letter with chlorate-rich water and have it stay dry while being disinfected. You'd also have the nasty side effect of the letter becoming quite flammable when the mist dried, if you sprayed any substantial amount of solution on it (powerful oxidizer, remember; unstable enough that it can even explode on its own if provoked enough).
Alternatively, they could just be doing standard electrolysis and burning the hydrogen and chlorine together to get hydrogen chloride. On contact with water (or bacteria) it'll turn into hydrochloric acid, and so would be quite poisonous.
Or they could be arcing through the air using the water as an electrode, to produce ozone or nitric acid vapour. The salt wouldn't be doing much in this scenario (except making the water conduct).
In summary, the possible reaction paths are a bit more complicated than you're painting, though I agree that the article's claims are at the very least exaggerated.
I use this in my backyard (Score:3, Informative)
The water in the pool is kept slightly salty. The pump/filter system then add electricity to the water in a controlled manner that causes the salt and water to "decompose" in to the constituent molecules that are deadly to bacteria (mainly chlorine and sodium). As the water leaves the control area the molecules recombine (mostly) to form salt water again. Some chlorine remains free and circulates in the pool.
the only thing different about the Russian system seems to be they may use more power as the story claims the device "dissolves"microbes. Then again chlorine "dissolves" microbes through oxidation.
Trivial details... (Score:5, Informative)
Unfortunately, some of the things Bruce has stated are not entirely accurate. The general facts are correct. but some bits need modification.
Hydrogen is reactive. It's only 'highly' reactive if you haven't played with really reactive stuff, like fluorine, chlorine and, er, oxygen. Potasium is fun too.. (I have only seen Cesium once. That's quite enough).
Skin only catches fire if you get it very hot. An uncontrolled fire in a pure oxygen atmosphere is more likely to vaporize the skin; then the fat underneath will start to burn. Pure oxygen at reasonable (3atm) pressure will not cause spontaneous combustion of people. But if a fire starts in that environment, then you won't be able to put it out. The fire in Apollo 1 was not spontaneous. It was started by an electrical fault. The three astronauts suffocated in flame. Not nice.
You can happily mix hydrogen and oxygen in a 2:1 ratio. You can pressurize the mixture to astonishing levels. If there's a lot less oxygen, you can breathe the mixture for days at a time (google for "deep hydrogen diving"). If you make a spark, then you'll understand just how reactive oxygen is. The lesson learnt will be very short, and terminally instructive.
But hydrogen and oxygen are not hypergolic. Ask a rocket scientist. Even the Space Shuttle needs a match to get it going.
Sodium is a disinfectant. In the same way that a raging forest fire is disinfectant. Kids! treating your grazed knees with sodium metal may sting! Also, your parent's lawyers will have to contend with a stupidity counter-claim.
Oxidizing agents and reducing agents are defined by their ability to grab or release electrons.
If you want to understand this stuff, find somebody who knows what "Gibb's free energy" is about. Then, get them to explain it to me...
Re:This is SO snake-oil (Score:3, Informative)
Oxidation is an increase in oxidation number. If a species increases in oxidation number, it has oxidized, regardless of whether or not oxygen was involved.
Take a portion of finely divided sodium metal. Spray some hot chlorine gas over it. You'll get an oxidation-reduction reaction. Like this:
2Na + Cl2 --> 2NaCl
Na's oxidation number goes from 0 to +1, so it's been oxidized. What did the oxidation? Well, there's no oxygen, so it must have been the chlorine. Chlorine therefore was an oxidizer in this reaction. The Cl went from 0 to -1, so it was reduced. This was a redox reaction.
It involved no oxygen. Sheesh.
See Quackwatch about colloidal silver (Score:4, Informative)
Re:cool (Score:1, Informative)
This is NOT true! (Score:2, Informative)
** SWIMMING POOL SALT CHLORINATORS ** (Score:2, Informative)
The solution was pioneered for swimming pools during the 60's [clear-water.com.au] in Australia.
I learned about saline chlorine generators when researching pool chemistry to find a solution for our daughter's special needs. See Therapy Pools links. [tmisaltpure.com]
An excellent overview of alternate water purification systems is 'Alternate Systems' by Neil Lowery [tmisaltpure.com].
Modern controls and polarity reversing/self cleaning have improved the chlorinators since the 60's. The convenience of computer automated electronic chemistry ORP/pH control [acu-trol.com] is nice.
I now believe that every pool owner should seriously consider saline chlorine generator for their pool. Most people cannot taste any salt at 2800-3500PPM. For more consumer info, follow the product links below:
Autopilot Pool Pilot Systems [autopilot.com]
Clear Tech Automation AutoClear [cleartechautomation.com]
Clormatic [clormatic.com]
Goldline Controls AquaRite [goldlinecontrols.com]
Monarch Pool Systems {various brands} [monarchpoolsystems.com]
Poolpower [poolpower.com]
TMI Salt Pure {excellent information, solution oriented} [tmisaltpure.com]
Zodiac Clearwater [clear-water.com.au]
There is likely more info here than anyone asked for... but our daughters needs motived some serious research.
It's amazing what one can learn by surfing. --Beachcomber