[pct-l] Aquamira info

[Bruce Harvey]

Andrew,

Thanks for your discussion.  Anything additional you could add  
regarding chlorine dioxide tablets?  Googling the phrase brings  
several hits.  A sample one is
www.backpackgeartest.org/reviews/Water%20Treatment/Chemical% 
20Treatment/Katadyn%20MicroPur%20Tablets/Steve%20Nelson/Initial% 
20Report/

Thanks


On Mar 5, 2009, at 2:58 PM, Andrew Jones wrote:

> You guys were asking for a chemist's opinion. I'm a chemist at a  
> brewery,
> where we use chlorine dioxide as a surface sanitizer, so here we go.
>
> First off, the shelf life of Aquamira. Sodium Chlorite solution  
> (solution A,
> I believe) is very stable as long as it's kept cool and away from  
> light. I'm
> not technically advising you to use Aquamira past its expiration  
> date to
> absolve my liability, but I can't think of a reason for it to go  
> bad as long
> as it's kept cool and relatively dark (I think it's in a solid  
> white plastic
> bottle...?).
>
> After mixing the solutions, the pH should drop to between 4-5, and the
> chlorite will start to convert to chlorine dioxide. It is this  
> molecule that
> has sanitizing activity, NOT free oxygen. *This is a gas in  
> solution*, so
> the life of the activated solution is somewhat short (a matter of a  
> couple
> hours, depending on concentration). For anybody that cares, what's  
> actually
> happening is an equalibrium is established between the chlorite and  
> chlorine
> dioxide. As the chlorine dioxide leaves the water (remember, it's a  
> gas),
> more of the chlorite is converted until it's gone. This gives the  
> solution
> moderate stability, but as I said, only for a few hours, after  
> which the
> concentration of both chemicals drops to a non-active level. THE  
> BEST OPTION
> IS TO USE IT IMMEDIATELY AFTER ACTIVATION! ONLY THEN CAN YOU BE  
> POSITIVE THE
> SOLUTION HAS THE CONCENTRATION INTENDED FOR USE BY THE MANUFACTURER.
>
> As for homemade kits, if you're a chemist and you know what you're  
> doing,
> feel free to go ahead, at your own risk. I will not give advice on  
> how to do
> this for liability's sake, but keep in mind the activation solution  
> must be
> between 4-5 pH, and I would only trust high quality pH strips to  
> check this
> unless I was VERY confident in my drop size measurement method.  
> These run
> $40 per 100, so you've just increased your cost 40 cents per  
> treatment.
> Hopefully I've talked you all out of this....
>
> And with all treatment options, remember, none are foolproof.  
> Measuring
> treatments by drop size is inaccurate, iodine tablets decompose  
> over time,
> no chemical treatment can really penetrate solid particles unless  
> given
> hours or days to do so, UV-C lights have the same problem with  
> particles,
> and filters honestly are only as good as their o-rings or membrane
> construction (also Cryptosporidium, for example, is small enough to
> penetrate some ceramic membranes). The ONLY 100% reliable treatment  
> option
> is boiling for at least 3 minutes! Not gonna happen! So what cold  
> treatments
> do is REDUCE the bacteria/viruses to a level that can be withstood  
> by an
> average human immune system. If you have a compromised immune  
> system, I
> would recommend using more than one treatment method every time.  
> Otherwise,
> just use the treatment of your choice, and quit your worrying,  
> you're going
> to make yourself sick!!
>
> Andy
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