Reid Harvey wrote: > Marshall, Ole Bob, Mike M., Ode, Everybody, > As I've occasionally updated here, our project aim is to get lowest > cost possible, household water treatment to the poor, large numbers > vulnerable to the diarrheal illnesses. Please help me out with > observations. As update, I'm still working away, toward a best > practice for silver saturating ceramic water purifiers. > > As I mentioned, for purifier saturation I'm beginning to lean away > from the application of CS, ionic and oxides or the metal, since these > forms of silver can be expensive and hard to procure from outside. > Soon I should be getting out details on the use of silver chloride and > silver nitrate in the purifier saturation and its use. The question > is this: could there be some deleterious health effect associated > with the use of silver nitrate and silver chloride, saturated in a > ceramic water purifier? I do not wish to forget any problem area, so > seeking observations.
Silver nitrate is very soluble, and would quickly wash out unless reduced to silver metal. Silver chloride has low solubility, but will also slowly dissolve. Both are considered to be somewhat toxic to the body, and both I believe can cause argyria in caucasions, nitrate for sure. I am not sure it would cause argyria in darker skinned people. > > > First indications show that silver chloride is a highly effective > disinfectant when properly situated within a ceramic purifier. It's > possible I'm missing some problem, but I do find it encouraging that > the 1000oC of the firing the purifiers is far beyond the burnout of > nitrates, at 500C. And for ultra small particles of silver chloride > dispersed within the media, this is a relatively insoluble material. I believe you will get few ppm of silver chloride in the water until it all dissolves. This low level may not be a problem, it is consistant with the amount of silver chloride the old protocol of adding a pinch of salt as a starter would produce. I would suggest firing some pure silver chloride to 1000 C and see what happens. I suspect it might very well reduce to silver metal! If that is the case I think that would be the way to go for sure. > > > So far my only small concerns are the waste byproduct of processing, > something like 100 mgs. of nitrate per candle. Then there's the > business of managing the sodium chloride, perhaps 50 grams of salt > that comes off. Perhaps this last I could recycle and reuse. Be aware that silver nitrate is very toxic to fish, to take care of how it is disposed. I still think that a mixture of CS, silver nitrate, and a developer could do wonders. Have you tried that? The CS would provide silver atoms/particles for the silver in the silver nitrate to plate out on, and the developer (even caffine works if you keep the ph right), will cause the silver to plate out onto the particles over a few minutes time. A way to do this without having to mix up a new batch each time would be to saturate the unit with CS, or put it in the original mixture before firing. Then once it is dry, slowly force a mixture of silver nitrate and developer through it. When the silver crystals are as large as you want (the whole thing should turn grey then black as the crystals increase in size), flush with clean water to remove the developer and silver nitrate. If you let it sit 15 minutes or so, then most of the silver nitrate should reduce, thus reducing wasted silver. Be sure to pick a developer that you can either completely wash out, or one that is non-toxic. I think caffine may be a good choice for that since it is pretty well non-toxic. For additional insight on this, I suggest researching photo developing techniques. Marshall > > > As to the silver made by electrolysis, of which I wrote some months > ago, I concluded that a quarter of this amount is ionic silver and the > remainder the oxide or hydroxide. I am imagining that this > concentrated silver, made by elecrolysis, would be very practical for > the treatment of static surfaces. But now, needing higher > concentration for our purifiers we're now looking at the chloride and > the oxide. However, it should be understood that colloidals islver, > as opposed to the other forms, should be uniquely suited to saturation > of static surfaces............ > > Yesterday I did come across an EPA reference page: > As to the possible toxicity due to the chlorides and nitrates of > silver, as per use within a ceramic water purifier, there appear to be > no specifics indicated in this EPA page. I don't know whether or not > this addresses the issue of overcoming objection to the chlorides and > nitrates. Or with respect to health and safety is there an issue of > whether or not there is any further guideline on processing these > materials. Sorry for being convuluted, exacerbated by my combining > health and legal aspects. I have no real idea of what to expect, but > would be happy for any helpful observations. > > All this is prelimary to finishing this phase of study, of course, > then publishing results. Any helpful observations would be > appreciated. The consequences of a missed step on my part could prove > unhappy, not to say difficult. > > So long. Or should I say how long. > Reid
