The paper specifically states for each test except 5 and 6 in my
original comments that the silver nitrate derived nanoparticles were
used so let's skip discussing silver oxide.
1) Figure 1(a) shows the composition of the silver nitrate derived
silver nanoparticle solution. Figure 5 identifies the XRD peak at (111)
to be Ag. And Figure 1(a) clearly shows a prominent peak at (111). The
broadening of peaks in Figure 1(a) is described as indicating the very
small sizes of Ag crystallites.
Figure 1(b) shows the composition of the silver solution after the
reaction with HCL. The Ag peak at (111) is greatly diminished.
Significant peaks at (200) and (220) now show in the XRD pattern. Figure
5 identifies the XRD peaks at (200) and (220) as belonging to silver
chloride.
Now, combine those results with the UV-vis absorption spectra shown in
Figure 2. The spectra of the silver solution after the reaction with HCL
indicates little or no silver particles remaining.
If the silver chloride resulted from only silver nitrate and not from a
reaction of HCl with the silver nanoparticles, I would expect to see
indications of the silver particles still there. I would also expect to
see smaller XRD peaks at (200) and (220) since little silver chloride
should be produced by residue silver nitrate. Your conclusions would
assume a level of incompetence in the researchers that is unimaginable
to me.
2) Figure 4 (There is no Figure 5) is for a separate test in which the
chemical reactivity of Ag nanoparticles in a polymer matrix was also
been investigated. A separate and unique polyacrylamide (PAM)/Ag
nanocomposite was prepared and used for the test. I believe that the
broad peaks in Figure 4 are caused by the PAM material. In any case,
Figure 4 is not relevant to the Ag/HCl issue.
Regards,
Steve
-----Original Message-----
From: Marshall Dudley [mailto:mdud...@king-cart.com]
Sent: Thursday, September 30, 2010 10:49 AM
To: silver-list@eskimo.com
Subject: Re: CS>CS and killing of pathogens - Comments on HCl Study
Can you specifically tell me what in that paper cannot be explained by
the known actions under such conditions of:
1. Small amounts of silver nitrate or silver oxide combined with HCl and
converted to silver chloride which precipitated out except for about .8
ppm.
2. The colloid aggregated from the drop in pH and also precipitated
out. Figure 5 indicates to me that the major conversion was from very
small consistent sized particles to much broader and varying sized
particles. The very small area under the curve of the HCl peaks tend to
indicate that very very little HCl was formed, as would be expected if
from residual nitrate or dissolved oxide, and the large increase in the
"background" indicate that a broad spectrum of particle sizes were
formed which is what would be expected if the particles aggregated and
dropped out of the solution.
I think one should go by prosaic explanations first, and only resort to
exotic explanations when the standard ones prove unsupported.
Marshall
On 9/30/2010 12:27 PM, Norton, Steve wrote:
> Marshal,
>
> Thank you very much for the article. Here are some comments on the
> study.
>
> The sequence of events I as read them are:
>
> 1) 2 versions of silver nanoparticles were created. One using silver
> nitrate giving a range of particles from 2 to 18 nm and averaging 8.2
> nm. This was called Solution A. The second used silver oxide as the
> source and had particle sizes similar to the silver nitrate version.
> This was called Solution B. The tests were performed using the silver
> nitrate based version. I see no instance where the silver oxide
version
> (Solution B) was used.
>
> 2) A solution was also created using large commercially available
silver
> particles (200 mesh). This was used only for the test demonstrating
that
> bulk silver does not react with HCl. That is the test that involved 3
> days of magnetic stirring. It showed no creation of silver chloride
> after the 3 days.
>
> 3) The concentration of the HCl used was approximately 18.5% HCl.
>
> 4)HCl was added to Solution A and a white product was formed
> immediately. X-ray powder diffraction (XRD) confirmed that little Ag+
> remained in solution and that AgCl was created. This was further
> confirmed by a UV-vis absorption test that verified the disappearance
of
> the Ag+ absorption peak at 302 nm.
>
> 5) The chemical reactivity of Ag nanoparticles in the polymer matrix
has
> also been investigated. Figure 5 shows results similar to (4) above.
> AgCl was created.
>
> 6) The test mentioned in (2) above was performed verifying that bulk
> silver does not react with HCl.
>
>
> I would have to say that it appears to me that the tests did indeed
> demonstrate that Ag nanoparticles have an unusually high chemical
> nanoreactivity in the reaction with hydrochloric acid. And a
> surprisingly rapid conversion to silver chloride.
>
> - Steve N
>
>
>
> -----Original Message-----
> From: Marshall Dudley [mailto:mdud...@king-cart.com]
> Sent: Wednesday, September 29, 2010 10:23 AM
> To: silver-list@eskimo.com
> Subject: Re: CS>CS and killing of pathogens
>
>
> I now have the full article. Anyone wanting it please let me know
and
> I will email it to you.
>
> There are some problems with their methodology.
>
> 1. They say they make CS by two methods, one which leaves a residue of
> silver nitrate in the solution, and the other which does not. I cannot
> find which one they used for the data they are producing.
> 2. They say that they remove all AgO2 from the non-nitrate solution by
> centrifuge. Fact is that it is impossible to removed dissolved silver
> oxide and silver hydroxide by centrifuge.
> 3. Their curve shows a rise on the front end which indicates silver
> oxide/hydroxide before adding HCl, but turns down after adding it,
> indicating that ionic silver was converted to silver
> 4. They say that adding HCl produced silver chloride immediately as
> evidenced by the solution turning milky, but that happens anyway with
> silver oxide or nitrate in the solution from reactions with them.
> 5. They assume that the loss of the colloid is by producing silver
> chloride instead of aggregation and precipitation when HCl is added.
But
>
> it is known that changing the pH of a solution significantly from 7
will
>
> cause aggregation and precipitation.
> 5. Figure 5 shows a peak for colloidal silver of one size particle in
> (b). In (c) it shows some AgCl peaks and a significant broadening of
the
>
> spectrum. This broadnening is I believe proof that instead of small
> consistent particles, it now has variable sized particles, as would be
> expected if the HCl was causing aggregation.
>
> There are too many holes in the paper for me to be convinced that they
> have not done junk science. I conclude from the data they have
supplied
>
> that the ionic portion reacted with HCl and that the colloidal portion
> aggregated, which is exactly what I would have expected.
>
> Marshall
>
>
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