Info wrote: > RE: CS>Warning for LV CSJason wrote: > > >When NIST, or any other qualified PHD scientist that does not > > manufacture equipment or sell products, states that TEM is not the best > > analytical method for analysing the most minute particles in colloidal > > suspension, then I'll take a second look. That said, I believe that any > > data you can acquire through studying any substance will provide > > valueable information. When you do comparative analysis of > > various products using the exact same method, the > > results are always enlightening. > > To get the right answer you must ask the right question. > > If the question concerns a colloid, with no ions present, then a TEM may > accurately show the particles. Sample preparation is very important and if > done improperly can produce images that have little to do with what is in > the colloid. > > If you ask a knowledgeable TEM operator about making images of ionic > solutions, they will tell you that what you will see are the compounds > formed when the sample is desiccated. > > A TEM operates under high vacuum so it is not possible to have water present > in the sample. A sample prepared for TEM viewing requires that the sample be > desiccated. When water is removed (evaporated) from an ionic solution, the > metal cations combine with the companion anions to form a solid compound. > > Here is what happens when the water is evaporated from an ionic solution: > > Silver ions in a solution cannot exist without water, so when the water is > evaporated the silver ions (cations) must combine with an available anion to > form a compound. The predominant anions present in a silver colloid solution > (EIS) are hydroxide and carbonate.
Where does the carbon come from? Absorbed CO2? > The compounds thus formed are silver > hydroxide and silver carbonate. Silver hydroxide is unstable and reduces to > silver oxide and hydrogen. I agree. > The silver carbonate will reduce to silver oxide > and carbon dioxide. Silver carbonate is a stable compound. It is available from Acros chemical with 99% purity. Why would it decompose unless exposed to light? > The final compound that remains is silver oxide. > > This process begins as a single silver ion is forced to combine with a > single anion forming a single molecule of the compound. The molecule has no > ionic charge and therefore no repulsive force. The lack of repulsion causes > the molecules to be attracted to each other by van der Waals' force of > attraction which causes them to aggregate and form small particles of the > compound. The size of the particle growth is limited by the reduced mobility > of the molecules as the water evaporates. What remains is particles of > silver oxide whose diameter is 1 - 3 nanometers. It is these particles which > predominate in TEM images made of silver colloid solutions (EIS) which have > a high ionic content compared to the silver particle content. I agree. > > > This is why TEM images of ionic solutions do not represent what was in the > solution. > Once again, I agree. Mashall > > The old saying applies "What you see ain't what you got." > > > Frank Key > Colloidal Science Lab. > www.colloidalsciencelab.com > > > > -- > The Silver List is a moderated forum for discussing Colloidal Silver. > > Instructions for unsubscribing are posted at: http://silverlist.org > > To post, address your message to: silver-list@eskimo.com > Silver List archive: http://escribe.com/health/thesilverlist/index.html > > Address Off-Topic messages to: silver-off-topic-l...@eskimo.com > OT Archive: http://escribe.com/health/silverofftopiclist/index.html > > List maintainer: Mike Devour <mdev...@eskimo.com>
