Calling all Chemistry gurus...

Ok, odd question but it does involve water and chemistry...let me preface with I am not a chemist nor do I play one on TV. I have garden pest I have it on very reliable authority can be eradicated by spraying with "colloidal silver" solution. This is derived by electrolysizing pure silver rods to a concentration of 20PPM. Using 3ea 9V batteries wired in series and passing 27V thru the rods in a flask on a magnetic stirrer for about 2 hrs. When I use my TDS meter(I verified it works by checkin my tap waster...110PPM)before process distilled water reads ZERO...after 2 hrs and lots of evidence of electrolysis(lots of charred material on the anode rod)but dag nabbit it still reads 0PPM. Can anyone help?

TFP

 - Would need one a doze hi scoo diplomas to answer dis here question.

Haha!!! I thought the same thing. I read the post and was like...um, ah...he said, ROD...

I'll email it to a chemist friend of mine and report back any answer he may have.

Thanks Karawolf and Anderson. At least your replies were an effort to help... I appreciate yer efforts with yer chemist friend. So Kara, I get yer point and actually did some quick reading to confirm that Silver is an ELEMENT and NOT considered organic. But I know that my TDS meter measures TOTAL dissolved solids....

"Total Dissolved Solids (often abbreviated TDS) is a measure of the combined content of all inorganic and organic substances contained in a liquid in molecular, ionized or micro-granular (colloidal sol) suspended in solution..."

So I SHOULD be getting a reading...a friend purchased a commercial CSG(colloidal silver generator) for $500!!! He gets a solid TDS reading with his. This is SO frustrating. Last night I tried the process again after a chem professor reccomendos a few drops of saline for a electrolyte...still evidence of Electrolysis but 0 PPM after 2.5 hrs...

TFP

Here is the response from my friend:

"So there are a few things:
When they say "colloidal silver" what do they mean? Colloidal silver is made up of very fine unionized silver particles (ag0). A silver solution will have some kind of ionized silver in it (most likely ag+1). They are very different things and you can't produce (very much) colloidal silver via electrolysis, you'll mostly end up with ions.

I couldn't find much info on pure silver electrolysis (most literature is about silver nitrate or silver chloride), but what little I could find seemed to indicate that 20 ppm via electrolysis is unlikely.

9 volt batteries don't provide much amperage, so while some weak electrolysis may occur it is probably not enough to cause a significant amount of silver to enter solution. It would be important to check that both the anode and cathode were pure silver and that they were situated as far apart in the solution as possible. Heating the distilled water before hand may help with solubility.

As with most things "colloidal silver" I would be highly skeptical that there isn't a cheaper and easier solution to the problem.

Nate"

I understand a TDS meter is simply a measurement of conductivity in the water. In other words, it is representing a measurement of resistivity in the water... in other words, how are particles inhibiting electrical flow in the water. Note I didn't say "how many" but rather "how are". Based on this conductivity/resistivity measurement, they use a conversion, from something like ohms to dissolved solids assuming a typical aquarium solution composition. So your TDS meter isn't going into the water and counting particles, but rather zapping a beam from one probe to the other and counting what % of the beam got through.

Now, silver is a very good conductor, probably closer to pure water than to water with dissolved poop (a good resistor from what I hear!). So when the beam goes through the particles, since they conduct more electricity than say poop, the TDS meter will see a high % of the original beam go through, and thus you would expect a low TDS reading.

I don't know the numbers, but you could probably look online for the conductivity of silver, water and carbon/nitrogen compounds to get a feel for the expected TDS ratio between the TDS meter and actual silver ppm. My guess is I wouldn't be surprised if it takes something like 2000pmm of diluted silver to register 1 TDS ppm in your meter.

(full disclosure, it's been like 20 years since my chemistry/physics classes )

Carefull you don't want to turn smurf blue

hobbyorobsession wrote:Carefull you don't want to turn smurf blue

  That was the first thing I thought about when I read it too.

Let me preface with this: I have taken 18 credits of college level chemistry, however I am no guru by any means.

Distilled water does not conduct electricity, upon the addition of a soluble ionic compound (NaCl, which becomes Na+ and Cl-) it does. I assume that a TDS meter is basically a measure of the ions (or lack thereof) floating around in your water by testing its conductivity. I would try to find an easily soluble silver compound, and then try to precipitate whatever anion that it is with, and then filter out the precipitate, leaving you with a solution of Ag+. You may be able to do this with electrolysis, but I dont think you will be able to using the methods you have described.