[pct-l] chlorine dioxide

[Dan Africk]

Thanks for that link(
http://www.lenntech.com/processes/disinfection/chemical/disinfectants-chlorine-dioxide.htm),
there is some very useful and relevant info on chlorine dioxide. I think
some of these are worth sharing:

"Chlorine dioxide is very different from elementary chlorine, both in its
chemical structure as in its behavior. Chlorine dioxide is a small, volatile
and very strong molecule. In diluted, watery solutions chlorine dioxide is a
free radical. At high concentrations it reacts strongly with reducing
agents. Chlorine dioxide is an unstable gas that dissociates into chlorine
gas (Cl2), oxygen gas (O2) and heat. When chlorine dioxide is photo-oxidized
by sunlight, it falls apart."

"Chlorine dioxide is 2,4 times denser than air"

"One of the most important qualities of chlorine dioxide is its high water
solubility, especially in cold water. Chlorine dioxide does not hydrolyze
when it enters water; it remains a dissolved gas in solution. Chlorine
dioxide is approximately 10 times more soluble in water than chlorine.
Chlorine dioxide can be removed by aeration or carbon dioxide."

This confirms what I already believed, which is that after treating a bottle
of water, if you shake it a lot and then open the cap after a while, much of
the chlorine dioxide turns into free chlorine gas which will then leave the
bottle. Now I know that sunlight also helps break it down, which tells me
that it would be better to put the bottle in a dark place for the treatment
time, and then expose it to sunlight when you want the ClO2 to dissipate.

On the other hand, "In water chlorine dioxide is active as a biocide for at
least 48 hours, its activity probaly outranges that of chlorine" This
contradicts the previous quote, so I'm not really sure what to make of it.

"It is a very strong oxidizer and it effectively kills pathogenic
microorganisms such as fungi, bacteria and viruses. It also prevents and
removes bio film" - So it might be a good idea to use this once in a while
in my water bottles, even when using a filter, to prevent/remove any
funkiness, when I don't have access to a bottle brush and running water to
clean it. Though boiling water probably works just as well.

As an aside, From what I know with any chlorine treatment, either clo2 or
bleach, you should smell a little chlorine when you first open the bottle
after treatment. If you can't smell any, then you should probably add more,
because that means that the chlorine has completely reacted with particles
in the water, and may not have reached high enough concentration to be
effective. From a chart on the linked page, regarding treatment of heavily
polluted water, apparently this is much more of an issue with
chlorine(bleach) than with chlorine dioxide.


One last interesting excerpt: "It is rarely stored as a gas, because it is
explosive under pressure. When concentrations are higher than 10% chlorine
dioxide in air, there is an explosion hazard."
Is anyone else tempted to waste a package of aquamira to see if I can make
some fireworks out of a water bottle? ;)

P.S. If you get the digest, please don't hit the reply button. The time it
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read through all the old messages looking for the new ones.