DrIronic101
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Purifying a formaldehyde solution w/ blue dye
I have a cleaning chemical (left-over) which contains formaldehyde and methanol that I would like to use in an up-coming experiment. However, it
contains a blue dye which would probably interfere with this. What would be the best way of purifying this product for use in experiments? Thanks!
"Technically, chemistry is the study of matter, but I prefer to see it as the study of change. Electrons—they change their energy levels. Molecules
change their bonds. Elements—they combine and change into compounds. Well, that’s all of life, right? It’s the constant. It’s the cycle.
It’s solution, dissolution, just over and over and over. It is growth, then decay, then transformation." -Walter White on what chemistry is.
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njl
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distillation sound reasonable. do you want just formaldehyde or a solution in methanol?
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clearly_not_atara
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You may be able to just convert it to hexamine and filter out the precipitate. The resulting hexamine will be reasonably pure.
https://www.nrcresearchpress.com/doi/abs/10.1139/cjr47b-062?...
However, I am not aware of good methods for recovering formaldehyde from hexamine, but sometimes you just want hexamine :p
EDIT: if there is a way, it should be in this thesis
https://ecommons.luc.edu/cgi/viewcontent.cgi?article=4186&am...
[Edited on 14-3-2020 by clearly_not_atara]
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Sulaiman
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The blue dye will probably be in trace ammounts only. (e.g. 1ppm)
(I can turn the water of an entire swimming pool blue by adding 5g crystal violet
- if clorine/bromine levels are low as crystal violet bleaches easily)
so, would the blue dye really interfere significantly ?
and, I'd try one drop of chlorine bleach or hydrogen peroxide on a small sample,
the blue may vanish before the methanol or formaldehyde are significantly oxidised,
if it is just the colour that you do not like.
(I suspect that the methanol/formaldehyde may slowly reduce the dye back to blue)
maybe activated carbon would absorb the dye ?
CAUTION : Hobby Chemist, not Professional or even Amateur
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anti
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You could try oxidising the dye or distillation. Try using a bit of H2O2. However, the dye SHOULD be present in trace amounts, as pointed out by
Sulaiman.
Maybe potassium permanganate. But then you would have to reduce it with a bit of sugar to get rid of the purple colour.
Please give us more information about the dye.
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DrIronic101
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Quote: Originally posted by Sulaiman  |
The blue dye will probably be in trace ammounts only. (e.g. 1ppm)
(I can turn the water of an entire swimming pool blue by adding 5g crystal violet
- if clorine/bromine levels are low as crystal violet bleaches easily)
so, would the blue dye really interfere significantly ?
and, I'd try one drop of chlorine bleach or hydrogen peroxide on a small sample,
the blue may vanish before the methanol or formaldehyde are significantly oxidised,
if it is just the colour that you do not like.
(I suspect that the methanol/formaldehyde may slowly reduce the dye back to blue)
maybe activated carbon would absorb the dye ? |
I suppose I'll try a bit of h2o2. I'll report back on what happens.
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Corrosive Joeseph
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It would probably help some if you post your MSDS
/CJ
Being well adjusted to a sick society is no measure of one's mental health
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draculic acid69
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Can formaldehyde solution be distilled like a liiquid with out it boiling the gas out of solution?
I'm doubting it.
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anti
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Actually, I think you're right. For the most part.
Formaldehyde tends to polymerise.
"Aqueous solutions of formaldehyde cannot always be concentrated satisfactorily by methods heretofore generally employed for such purpose for the
reason that such methods involve the fractional distillation of an aqueous formaldehyde solution with the recovery of a distillate which in some cases
may have a concentration of formaldehyde not substantially greater than the concentration of formaldehyde in the solution originally treated.
Depending upon the formaldehyde concentration of the solution originally treated, such prior methods may yield a vapor which has a high concentration
of anhydrous formaldehyde, part of which undergoes polymerization to paraformaldehyde at the temperatures employed, producing sufficient quantities of
solid paraformaldehyde to clog the condensers and vapor and distillate lines, making operations difficult and uncertain, while unpolymerized anhydrous
formaldehyde is difficult to recover because of its very low boiling point and high vapor pressure."
http://www.freepatentsonline.com/2153526.html
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S.C. Wack
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Distilling aq. solutions isn't a problem. Something like an azeotrope of 10% comes over on simple distillation if you have at least 90% water. This on
vacuum distillation gives a distillate with barely an odor up to the point where the residue solidifies on cooling.
The problem is methanol which is not at all unreactive. The reactions are I think reversible hot, for sure if mixed with a lot of water, but maybe not
at vacuum temperatures.
[Edited on 15-3-2020 by S.C. Wack]
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