On 9/30/2010 3:03 PM, Norton, Steve wrote:
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.
I presume you mean figure 4, there is no figure 5. Actually they
identify it as Ag(111). Do you know what these number (111, 220) are
referring to? Somehow they do not make sense, for instance in Fig. 1(b)
311 is locatd between 220 and 222, and 222 is located between 311 and
400. Also the 111 peak jumps around depending on where they seem to
want it, moving far left on the 1(b). Somehow this does not seem right
and is inconsistent with other paper's reports of these peaks.
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.
The peak at 111 is simply one of many possible forms of Ag crystal,
including 200, 220 and 311.
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.
Are the peaks at 200 and 220 REALLY silver chloride? Figure 1B of
another paper ( www.springerlink.com/index/710W187LW403T65T.pdf ) says
that this is simply different forms of silver crystals - "Figure 1B .. A
number of strong Bragg reflections can be seen which correspond to the
(111), (200), (220), (311) reflections of cc (cubic crystals of)
silver." If this is accurate, and I believe it is, that completely
blows their theory out of the water since these peaks correspond with
aggregated silver crystals and not silver chloride. Since (111) is I
believe the smallest crystal form, then that it diminishes and the other
forms increase is completely expected when particles aggregate into
larger crystals.
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.
This is true for both of our analysis. They presume that the silver
chloride precipitates out, I presume that the aggregated silver
particles precipitate out. That is that this result supports both
hypothesizes. Actually it is VERY easy to test which is correct. Take
some 20 ppm EIS, and add a pinch of salt to it and let the silver
chloride precipitate out. Then add the HCl and see if you get any
additional silver chloride, if not then I am right, if so then they are.
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.
Not if they aggregate and precipitate out as I have found they do when
the pH is dropped significantly. Colloidal silver is only stable in
water that is very near neutral or pH of 7. I see nothing that they are
doing that would prevent this expected aggregation and precipitation
when they drop the pH significantly.
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.
No, they should be larger. First when hydrochloric acid is added to
silver nitrate it produces silver chloride and nitric acid. But that
should not change the peaks at 200 and 220 since those are crystalline
forms of silver (see additional analysis of this below). When the
crystals aggregate then the 111 drops and the higher orders increase.
These lines are NOT silver chloride but simply larger silver particles
as expected. I am not making any assumptions, I am simply analyzing the
data, but I do question their competence somewhat now upon further research.
If we follow what happens if ANY silver nitrate is present we get the
following actions:
AgNO3 + HCl - > AgCl + HNO3 (nitric acid)
HNO3 + Ag - > AgNO3 + HCl
This means that if you have ANY silver nitrate available, it will take
place in a sequence of actions that will result in the conversion of
silver to silver chloride when HCl is added, but will remain unchanged,
that is it would be an active catalyst. Thus even if silver chloride IS
generated when adding HCl, the results are nullified if there is even a
trace of silver nitrate available since it would be taking place in the
reaction.
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.
Except they are erroneously attributing the 200 peak to Silver chloride,
when in fact it is the peak of one of the crystalline forms of silver
particles.
Marshall
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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