>
>Colloid chemistry is a complex field and only those involved know much
>about it. It is not surprising that many chemists no little of colloid
>properties. Indeed not many chemists know much about electrolysis. To
>make matters worse, metallic sols are an obscure subset of colloid
>science. There is not much call for nano-sized pure metal solutions,
>even though nano-sized metallic powders are showing new and exciting
>properties and are under active investigation and experimentation.
>There is some use for gold sols in marking organic molecules for
>measurement etc. and these sols do display the characteristics of
>changing colour with particle size.***
>
>>
>> 2nd subject
>***The Tyndal effect is often included in the formal definitions of
>colloids vs solutions, but is only a minor effect which has been over
>shadowed by such effects as Raman scattering etc. which are the basis
>for many laser particle sizers. However, you will be hard pressed to
>find particle sizers that measure below 10nm, and even these are
>pretty sophisticated lab models. To measure below about 2nm is quite
>difficult and measuring the speed of particle travel is often
>employed.***
^^^## On that note, My friend says the light shift effect, at least in atmospheric application, is due to [UV] light accelerating particles and the color will always shift downwards into the less energetic as the particle absorbs whatever frequency of light that accelerated it. I presume that yellow is a less energetic frequency than UV? Shifting to red is certainly common enough in the sky.##
>> >========================
>>
>> >
>> >The colour of a colloid is dependant on the particle size, and
>> >how that affects the reflection, refraction and extinction of
>> >visible light. The smaller the particle size the smaller the
>> >wavelength of light it will absorb leaving its complimentary
>> >colour to be transmitted.
>
>***Colorimeters use a complexing agent to bind with the specimen, the
>resultant colour density is measured.***
### OK ##
>
>> Also, why does that color stick to the glass after storing for
>several weeks leaving the suspension clear yet still potent?
>> Do I have defective glass? Has anyone else noticed this? Honest, it
>happens without fail, for me at least.
>
>*** The colour is a property of the particles plating out upon the
>walls. The question is why do particles plate out at all ... the
>answer no doubt includes all sorts of reasons, including particle
>size, the charge of the particle, the particle makeup etc. I do not
>have this problem myself, but the vessels I use to generate in, do
>show plating on the walls.***
##^^ Yes, this happens with me too, especially when using cold water and letting the generator run for several hours, but that's not what I'm talking about.
What I'm saying is that AFTER the process is complete and after the CS is placed in a storage container, the color migrates to the container leaving the suspension clear, with a good T.E. and metallic flavor. It takes several days or weeks for this to happen. This is different from silver plate out that occures while the suspension is still energized.###
>
>
>[It seems clear that the colour of colloids is both a function of
>particle size and light absorption.
>The particle size would seem to influence which wavelength is
>absorbed, and so which is transmitted , reflected and scattered.
>The concentration effects the colour depth as per Beer's Law.
>
>From:
>
>http://www.svpvril.com/Tyndall.html
>
>If the particles are much less than 0.1 micron in size, they may be
>difficult to discern even with an ultra-microscope, but the beam of
>rays passing through the liquid will still be observed. Finally, if
>the particles are as small as 1 millimicron, the light scattering
>becomes so insignificant that this phenomenon also disappears and the
>liquid appears quite homogeneous or, as we say, "optically void."
>Such, for instance, are ordinary solutions of various substances.
## I ran a little experiment with table salt dissolved in distilled water. To my surprise, it had a strong T.E. Now, several days later, the T.E. is much dimminished but still present....no visible precipitate.
>
>From:
>http://chemwww.bham.ac.uk/research_labs/Research_Profiles/gbpeacock/co
>lloidal.htm
>
>Colloidal, Nanoparticulate Gold
>
>For a long time now, one of the fundamental scientific conundrums has
>been the crossover between discreet molecules and bulk solids. The
>behaviours of both are well known and studied, but the intermediate
>ground - particles which are neither molecules, nor solids - is more
>of a wilderness. This is the area of clusters, nanoparticles and
>colloids - entities with dimensions of the order of a few nanometers -
>containing a finite number of atoms. One of the most striking examples
>of finite-size effects is the vivid red colour of colloidal gold, used
>since ancient times for colouring jewellery and staining glass. The
>colour arises from a collective oscillation of electrons within the
>finite-sized fragments of metallic gold. Nanoparticles of gold remain
>suspended in water by Brownian motion, although their charged surface
>means that they are severely solvated, and almost certainly have other
>ions associated with these otherwise unstable clusters.
>
>From:
>http://mole.chm.bris.ac.uk/goodwin/simon.htm
>
>Semiconductor Nanoparticles
>
>My Ph.D. research centres upon the formation and growth of colloidal
>nano-particles within complex surfactant media. There are many
>industrial applications for ultra-small colloidal particles. For
>example, nano-particles have been incorporated in printing inks. In
>fact, colloidal particles could be used for virtually anything
>coloured (paints, cosmetics, lipsticks, see 9/9/95 issue of New
>Scientist). The colour is changed by tuning the size and size
>distribution of the colloidal particles.
>
>It is the optical properties of nano-particles that are of particular
>interest here. Precise control of the colloids' scattering and
>absorbance properties may be achieved by their growth in surfactant
>media
>
>From:
>
> http://www.sciencedaily.com/releases/1998/11/981123081416.htm
>
>Microbiologist Develops Method For Dyeing Fabrics With Gold
>"The reagents reduce metallic ions, which are then formed into
>particles and grown," Todd explains. "By controlling their size, we
>can vary the color.
>
>"The particles are so small they can't be seen with a microscope," he
>adds. "But they produce a bright signal with a very small amount of
>metal. And since metals can be combined into alloys, different
>combinations can produce a variety of colors."]
>
>It must be remembered that colloids exist in a state of tenuous
>equilibrium, dependent on the balance of the forces of dispersion and
>the forces of attraction. And it does not take much to alter this
>balance. Colloids do not exist as single atoms (or ions) but discrete
>groups of these. It is thought that the groups of atoms form fractal
>arrangements, which means definite steps in size and stability. It is
>my view that when CS is formed with a low current density, the atoms
>form small groups, and become solvated quickly, resisting further
>grouping of these groups into larger fractals. Mechanical dispersion
>helps in this regard. In this way, there is little fallout, and
>minimal dendrite formation on the cathode. One can generate clear sols
>of high concentration in this manner, that are very stable.
### Crystaline structures are fractal in nature?
" Elemental Silver has a face centered cubic crystal structure."
>
>> One pole produces hydrogen
>> Other observation of tarnish on silver tells me that silver oxides
>can take on several colors including all those mentioned above.
>Granted, there may be numerous chemicals floating around in the air to
>account for that color variation. Perhaps no relationship?
>
>*** Firstly, the tarnish found on silver in air is not silver oxide,
>but silver sulphide. Silver is stable in oxygen and water.
### OK, maybe not related...but... " Silver sulphate, a white precipitate...silver phosphate, a yellow precipitate...silver sulphide, black..."
I find three different silver oxide compounds mentenioned.
1] "Ag2O the normal oxide of silver made by action of oxygen under pressure at 300 deg C or by precipitation of a silver salt with carbonate free alkali metal hydroxide."
I believe you mentioned something about the formation of silver hydroxide under certain voltage parameters of hydrolysis?
2] "AgO is formed when ozone reacts with silver"
I notice increased formations of black stuff when using fresh ozonated distilled water. If the water is heated or allowed to stand for several days loosely capped, the deposits are greatly reduced. Furthermore, on one website that loves that yellow color recomends the use of ozonated distilled water saying they get a nicer richer color when ozonated DW is used. [a para quote]
3] Ag2O3 "has been obtained in impure state by anodic oxidation of silver"
Maybe that applies?
{{ Quotes are from Van Nostrands scientific encyclopedia 5th edition 1976}}}
Incidently, this encyclopedia makes two mentions of silver being used in minute abounts to kill bactria, specifically referencing its use in water treatment.
I think that any componds that could possibly be made, would be made, under the ionic energized conditions of electro-colloidal silver production. There is massive reaction surface available and free electrons going everywhere and a varying range of voltages and currents. [depending on the type of generator and stage of process]
>
>Secondly, the reason that there are no observable oxygen gas bubbles
>at the anode is because there is none.
## Actually, there are "some"...just not many. And that pole gets quite black.
Add that to qoutes about silver oxides and the fact that silver oxides are dark colored [but see no mention of exact colors for each oxide form] so it stands to reason that the oxygen is oxidizing silver ions.
It may also be creating silver hydroxides which further react to form silver oxide#1 Ag2O
>The reduction potential (the energy required to remove an electron) of
>silver in water is 0.79V, the reduction potential water into oxygen
>gas is 0.815V which requires slightly more energy, but in fact
>electrolising water requires an overvoltage of about 0.6v which means
>the actual voltage reqired to produce oxygen is double that required
>to produce silver ions.
## Moot point? Starting voltage for me is between 24.5 and 29 volts going down to 6 volts. More than high enough for electrolysis and to produce silver ions as well?
Under a low current the reaction is that which
>requires the least energy. Silver is oxidised preferentialy to water.
## Not sure what that says but it sounds like silver will oxidize more easily than water. Does water oxidize? Certainly water will hold dissolved oxygen...which will probably find a silver ion pretty fast and start swapping electrons. [making a compound]
>
>The situation is different at the cathode, hydrogen gas is produced at
>0.41v but needs an overpotential of about 0.3v, netting just over 7v
>under but very close to that required by silver.
>Therefore you will see hydrogen gas bubbles but not oxygen.
## But I do see some oxygen bubbles form. It doesn't hang around long or bubble off.
>Silver is much more likely to form silver hydroxide than silver oxide
>in any event, and it is likely that there is a small amount of this
>present in the solution.***
## Again, forming oxide #1 under present energetic conditions ?
>
>>" By all indications I find it likely that, if the theory is accurate,
>it's being applied to the wrong particle and make no mistake, there
>are 'at least' two distinct and different molecular structures, quite
>easily observable, present in low voltage CS production. Their
>location and concentration varies." [KD'C]
### Shoot , now I see at least 4 possible combinations other than pure metallic silver. The color of the plot deepens.
>>
>> A note on HVAC. If the electrodes are open to the atmosphere you'll
>get ozone [which will oxidize silver ions even more violently than
>pure oxygen], nitric acid [if there is moisture and atmospheric
>nitrogen present and since the discharge is into water...moisture is
>present.], hydrogen and oxygen become a part of the nitric acid. So,
>there will also be some silver nitrate made.
>
>***Only if the electrodes arc and ionise the air.***
## Agreed. Air must be involved.
>
>> If the electrodes are submerged in water, they still produce ozone,
>oxygen and hydrogen but little or no nitric acid. If there is no
>current control, all this stuff emulsifies into a sludge which very
>quickly turns black. [I have a HVAC generator that does just that in
>less than 4 minutes]
>> I understand that the leading HVAC unit isolates the electrodes from
>the atmosphere and doesn't allow direct contact with water. A Very
>good idea that probably makes very good CS.
>
>*** Again, the electrodes must arc to create ozone or H202, this is
>acutally closer to Bredig's system than most realise, he arced
>submerged DC electrodes, if my source is correct. I know of no HVAC
>colloidal silver generator whose electrodes do not contact the water,
>at least after start up.
## Maybe they do arc [Oh, you said that] in a self created pure oxygen / hydrogen atmosphere within the surrounding water. As we see in the 'quotes'above, ozone reacts with silver. The 'Silver Genie' I have uses submerged electrodes with high voltage, makes LOTS of bubbles fast enough to actually emulsify the water and produces black sludge in mere minutes. Under AC arcing, water split into its componants should recombine, but the instructions for the Silver Genie give a clue that perhaps it uses high voltage DC. That would account for the emulsion seperating into two layers. It doesn't specify which [AC/DC].
>
>Ozone doesn't do anything to silver ions, these are already oxidised
### Hold on there! If it's oxidized it has formed an oxide. Ozone DOES react with silver according to the scientific encyclopedia and since ozone is oxygen in it's most corrosive unstable radical form...
>and the energy required to remove a further electron from the Ag+ is
>more than ozone can supply.
### There are massive amounts of energy available from the power supply not only from the ozone. Granted, ozone will not ionize silver but it will oxidize.
However both ozone and H2O2 will oxidise
>metallic silver, producing water and O2 gas in the process.
## A silver ion is metallic silver with an extra electron..or is that minus an electron? I see also references to ionic crystals but no specific mention of silver ion crystals, how they are formed or thier maximum size.
An
>interesting experiment, and one which should put to rest the idea of
>silver oxide inclusion (I think) is to add a few ml of H2O2 to some
>yellow CS, if there are any metallic silver particles they will be
>oxidised to Ag+ amid much bubbling and the colloid will probably
>become clear, as the large particles are oxidised and broken into
>small ionic ones. The H2O2 when applied to ionic yellow colloid with
>little metallic inclusion will have no reaction and not lose colour,
>H2O2 being stabilised by silver ions and probably visa versa.***
## Or maybe seperate the yellow residue I find on glass and subject it to ozone and see if it oxidizes, Heat it up and see if it de-oxidizes and makes a silvery coating, then subject the clear suspension to ozone and see if it turns whatever color.
>
>***Yes well, don't get me wrong... we have talked about this in the
>past, and the consensus would be, that colloidal silver is quite safe
>and effective as a clear solution or as a light golden one, with clear
>being the one to strive for.
>Even if silver oxide is present it does not present any more of a risk
>than does silver.
>Hey, no offence taken... nice to meet you!***
## Glad for that and completely agreed with a light color not being a problem. But as you can tell, I'm still not satisfied with what people tell me that color is. Personally, if I can leave that color on the glass...and I can...that is preferable.
KD'C
>>
>
>Ivan.
>
>
>
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