wilkaaro - 11-10-2010 at 14:03
I was wondering if anyone had a quick efficient way to do this? I have a .07M solution of Silver Nitrate disolved in 95% ethanol, and I want reprocess
the ethanol? So far the only thing I've really tried was a seperatory funnel with a kimwipe and some silica.
Jor - 11-10-2010 at 14:30
I'm not entirely sure, but aren't ethanol and silver nitrate quite incompatible, especially when acidic? I recall it may form silver fulminate, even
more sensitive than mercury fulminate. But this is what I remember, I might be wrong. I am quite sure however that silver fulminate may be formed when
the pH is very low (e.g AgNO3, in conc. HNO3 reacting with ethanol).
Magic Muzzlet - 11-10-2010 at 15:33
Why not just distill it? As I understand you just want to reuse the ethanol.
siver nitrate solution
cyanureeves - 11-10-2010 at 17:12
if silver nitrate is in solution wont it react with a sodium chloride solution and make insoluble silver chloride.silver chloride is easy to filter.
not_important - 11-10-2010 at 19:36
Or Na2CO3, giving silver carbonate which is easier to process into useful silver salts. However the solution still needs not to be distilled to close
to dryness even if alkaline.
wilkaaro - 12-10-2010 at 12:38
I was hoping to avoid distilling I have almost 55 gallons to distill.
not_important - 12-10-2010 at 13:33
Then cation+anion ion exchange resins, just like for deionising water. Replace Ag(+) with H(+), NO3(-) with OH(-), and you end up with slightly
wetter EtOH. Likely the Ag can be displaced from the spent resin with aqueous sodium or ammonium nitrate, if you'd like to recover it.
bahamuth - 12-10-2010 at 14:08
You have close to 2.5 kilo on AgNO3 in your ~55 gallon of EtOH, a lot of silver...
What are your plans for the ethanol afterward? Drinking, lab use?
Anyway, what i would do is to add (slowly to avoid precipitation, and under heavy stirring) a slight molar excess (1.02 molar excess) of potassium
chloride dissolved in the same ethanol(solubility stated as 40g/L EtOH by the Merck index) to the ethanol, let the insoluble AgCl sediment and decant
of the ethanol, use this scaled up: http://www.amazingstill.com/no/Plastbrenneren.pdf to "distill" the ethanol. The apparatus in the pdf is used to distill moonshine, takes time,
especially with 55 gallon but removes the need for a mega glass still... If you want the EtOH for lab use you would need to distill it anyway in a
glass apparatus...
The silver chloride I would reduce with regular sugar in conc. NaOH+heat, filter and clean and store for further use.
zed - 13-10-2010 at 05:00
The reaction of Silver Nitrate with the Chloride ion, usually produces colloidal precipitates, that may be very difficult to filter. They are slow to
settle out, and the particles are so small, that they clog most filter papers.
[Edited on 13-10-2010 by zed]
bahamuth - 13-10-2010 at 13:19
Recovering large amounts of AgCl from Mohr's chloride titration waste I found that if you the stir colloidal AgCl suspension for some time it
aggregates and settles faster after ended stirring, do not know if this will be easy to do if you do it on 55 gallon scale.
Edit: The AgCl might not stay suspended in the EtOH as long as in water due to less polarity of the ethanol..
Also, IIRC when I gravimetrically determined sulfate at school we had the solution hot before adding Ba(Cl)2 to induce growth of larger crystals of
insoluble BaSO4 for easier filtering, might be possible here also, if indeed i am correct about the hot solution/larger crystals....
[Edited on 13-10-2010 by bahamuth]
wilkaaro - 13-10-2010 at 14:58
I'm going to try to distil using the bucket method from the pdf that bahamuth provided. I'm using it in the lab again, something about absolute
ethanol distilled with benzene freaks me out for consumption.
bahamuth - 14-10-2010 at 06:40
I would remove the AgNO3 first somehow,as it might oxidize the ethanol, possibly even with slight heating, this I am not sure about just to have it
said.
Also, some of the AgNO3 might decompose by light, give of enough NOx to react with the small amounts of water left in the ethanol, turn into nitric or
nitrous acid and further catalyze the formation of silver fulminate... Just speculations of course...
zed - 14-10-2010 at 15:09
Forming the Silver Chloride in a very hot solution, should indeed increase the very slight solubility of AgCl somewhat, allowing more time for crystal
growth, and thereby increasing the crystal size.
As for consuming tax exempt ethanol....Don't entertain such thoughts in the US. Somewhere out there, there is an ATF agent that got an erection when
you mentioned the idea.
You screw the US Government, out of their tax money, and the ATF screws you. The individual states also levy a tax.
US tax is $27/Gallon of 100% Ethanol. Forty Gallons, equals about 1080.00 Dollars. Agents tend to be understimulated, bored, and itching for
action. Leading you away in handcuffs, could be the highpoint of the week.
[Edited on 14-10-2010 by zed]
[Edited on 14-10-2010 by zed]
peach - 15-10-2010 at 03:55
Here's some more information on the bucket still (alcoholics dream) method
It's won't get it very pure, but it'll knock a lot of the water out for not a lot of effort or expense. Then the rest can be cleaned up with
glassware.
Remembering, the water / ethanol azeotrope breaks somewhere under about 70mBar.
If you get a sturdy enough container, you may even be able to get the thing boiling. There are heavy duty shipping barrels that are designed to
withstand a blasting with boiling water / steam to re-sterilize them for the next batch of food products to go in (olives in the case of mine, it
smelled really nice on arrival!
)
I absolutely love mine. I got it for £10, and can kick it round the floor and it barely does anything to it (it's designed for serious shipping
abuse). The lid has a big retaining ring that screws on and a rubber seal. Since it's plastic, porting the lid to take bits of equipment is easy; e.g.
push fit plastic plumbing is rated to 3bar at 70C, and the connectors just screw to seal with rubber or push in. A 200l sterilizable fermenter /
whatever you can think of that's compatible, portable reactor. Nice.
I haven't checked, but I think it may be HDPE given the toughness levels, which is the best you'll get in terms of plastics prior to going for the
fluoropolymers. I think you can actually buy fluoropolymer barrel liners for storing chemicals as well (a bin bag made of it that sits inside); lots
of the metal ones have a liner of some description if it's for chemical storage (liners like, a spray of thick epoxy).
Polypropylene can withstand autoclaving as well. Pretty much all the disposable, premade, melt sealed food you buy in packs is in that, because it can
be made reasonably transparent to let the customer see the goodness inside. But it also starts going a bit soft at those temperatures. Polysulfonate
is another, but that costs a god damn fortune! And it's mainly for biology lab equipment (Nalgene membrane vacuum funnels for collecting cells /
spores / bacteria, the amber coloured ones).
John
[Edited on 15-10-2010 by peach]
zed - 20-10-2010 at 17:03
Turns out, KNO3 isn't very soluble in ETOH either.
Might be able to freeze it out. Though, all things considered, since it is such a large amount of ethanol, distilling might be easier.