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peach
Bon Vivant
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@NI & smuv
Ar huh, it'll be surface tension.
There are permeable membranes that can do some fairly neat tricks with solutions.
Maybe a film of the silicone would work for alcohol and other miscibles?
Organics tend to soak into plastics. The halogenated solvents will do it with PTFE and the other fluoropolymers. Say I had some PTFE tubing and filled
it with damp DCM, the PTFE would, to some extent, separate the two. I have a video on there were I'm replying to a guy a Saint Gobain about some
tubing he sent me to try, and I explain how it swells up. They mention that on their site and the guy had already seen that happening, and I predicted
it would happen. So it's a known effect and not random chance or unknown interactions. Obviously, there is the possibility a very thin film of PTFE,
or one of it's friends, would work for that.
I am trying to produce a continuous film of just the silicone at the moment, so I'll have a look and see if it's done it tomorrow. If it has, I'll add
that to the list of things to try.
Chemistry forums seem full of alky's trying to get drunk even faster. 
@Picene
About 1.5, 1.75l, out of which I need around 150ml, stuck in the boundary.
I may see if I can get it through the washing machine in bottles and if the g's in a high speed spin cycle will be enough to help.
Tried salting it, and freezing. Not much luck.
I know there are emulsion busting additives available, but that means buying more bottles of things at the moment. Bottles which may not function for
the mountain of gunk at the boundary.
I'm trying to extract nicotine from cigarette butts. Almost 200 of them. I washed with 5% NaOH to freebase it, then blended to get the filters smashed
up; already having stripped the papers by hand. The blending and base seems to have been enough to digest the filters, which (combined with all the
now saponified tars) is the mass of gunk at the boundary, trapping the xylene.
[Edited on 8-10-2010 by peach]
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peach
Bon Vivant
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I checked the xylene soaking papers. They've been in there, submerged, for 6-9h.
Let them dry, tried the water. Both let the water through, at a very slow rate.
However, I noticed the meniscus was still flipped, and the paper wasn't whetting normally. And that, when I messed with the paper, the rate shot up.
Lifting the paper out, it seemed to be dripping only from the crimped seam at the bottom. As I had to fold the papers up to get them in the xylene, I
figured I may have damaged the seam (where they usually break).
I cut swatches from the walls of the papers and am looking at water penetration for those. Thus far, ~45 minutes on, not a single drop has gone
through.
Again, pretty predictable stuff. If you scrumple coffee filters up, bend them, fold them, the seam is going to start going with or without the spray.
It's either the paper it's self opening to a point where normal capillaries have formed again due to the seam parting, or it's opened a little and
broken a film of the silicone.
Whichever it is, it's not a problem. Unless you plan to soak for 6-9h in xylene and be folding / bending the papers in the process. These ones are
reused as well.
I don't recommend spraying a normal flat disc, then fluting it, as you may damage the effect. Flute, then spray. With a flat filter paper, as you'd
normally use in a Buchner, that's a lot less of an issue; kind of, not an issue at all, as there are no seams and it's not folded or bent.
There's ANOTHER test. Bend / fold up flat discs after spraying and see if they leak. If they do, it's a film of silicone breaking. If not, the coffee
ones are the seam parting. Which will demonstrate whether the spray is penetrating to a fibre by fibre level or not.
See how they're doing tomorrow.
[Edited on 8-10-2010 by peach]
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smuv
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Quote: Originally posted by peach  | @NI & smuv
Organics tend to soak into plastics. The halogenated solvents will do it with PTFE and the other fluoropolymers. Say I had some PTFE tubing and filled
it with damp DCM, the PTFE would, to some extent, separate the two. I have a video on there were I'm replying to a guy a Saint Gobain about some
tubing he sent me to try, and I explain how it swells up. |
That's different, it swells because of solubility or the organic in ptfe; that is simply an extraction,the partition coefficient has nothing to do
with how porous the pfte is (the kinetics do however), and is therefore a completely different system.
[Edited on 10-8-2010 by smuv]
"Titanium tetrachloride…You sly temptress." --Walter Bishop
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aonomus
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http://www.informaworld.com/smpp/content~db=all~content=a779... is an interesting note describing the use of phase separation paper in a vapor
path. The authors note the eventual dissolution of the silicones over time with organics, as well as the potential for backpressure buildup.
I don't think that phase separation paper will work for a solvent drying system unfortunately since it can't remove trace dissolved amounts. You
wouldn't pour solvent into a SPS that had visible immiscible water droplets in it anyway, so the best thing to do would be to use it to substitute
separatory funnels to save time and glassware cleaning.
Because it uses wetting, vacuum filtration is probably out of the question as well.
I have some scotchgard spray which I might try impregnating onto some Whatman filter paper and drying, we'll see how that turns out.
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food
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hey
you didn't mention celite here
I'm curious; I'd read that read that vacuum filtering through celite (or diatomaceous earth for the $ challenged?) was an option for stubborn
emulsions. I've never tried it, but I've a plastic bottle of diatomaceous earth ('Insectigone'; guarantee: silicon dioxide 80% available as
diatomaceous earth ) just waiting to go. Any thoughts?
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Hexagon
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| Quote: Originally posted by food | hey
you didn't mention celite here
I'm curious; I'd read that read that vacuum filtering through celite (or diatomaceous earth for the $ challenged?) was an option for stubborn
emulsions. I've never tried it, but I've a plastic bottle of diatomaceous earth ('Insectigone'; guarantee: silicon dioxide 80% available as
diatomaceous earth ) just waiting to go. Any thoughts? |
I've heard that sticking a vibrating dildo to your separatory funnel does wonders on emulsions...
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smuv
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| Quote: | | I'm curious; I'd read that read that vacuum filtering through celite (or diatomaceous earth for the $ challenged?) was an option for stubborn
emulsions. I've never tried it, but I've a plastic bottle of diatomaceous earth ('Insectigone'; guarantee: silicon dioxide 80% available as
diatomaceous earth ) just waiting to go. Any thoughts? |
It works. Simply filtering through fritted glass (I assume filter paper as well but don't have experience with that) helps break up emulsions.
"Titanium tetrachloride…You sly temptress." --Walter Bishop
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spirocycle
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I dont understand
what do you mean by "break up emulsions"
will one component go through first?
or will the whole lot go through, but be in two distinct layers in the collection vessel?
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Mister Junk Pile
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Some water repellent products use fluorinated surfactants to induce hydrophobicity. It is likely that these would be much more resistant to being
dissolved by organics than regular siloxanes. In fact, at least one perfluoro acid salt is almost completely insoluble in at least 20 different types
of organic solvents. This would be the potassium salt of perfluorooctanesulfonic acid.
If the acid could somehow be deposited on the paper as the potassium salt I believe it would last a VERY long time. I suspect the paper would begin
to fall apart before that compound fully dissolved regardless of what solvent was passed through it.
Maybe the acid could be dissolved in a solvent and then a potassium base could be added to precipitate the salt on the paper somehow.
I know this isn't exactly "at-home" stuff (PFOS happens to be quite expensive but maybe a little bit would go a long way?), but it's interesting to
think about.
[Edited on 11-9-2010 by Mister Junk Pile]
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franklyn
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Commonly available in pint to nearly quart size , a liquid dish soap plastic bottle
is an effective improvised separation funnel. The kind with a telescoping spigot
that snaps close serves well as a stopcock. A small hole in the base of the plastic
bottle just large enough to let the stem of a funnel to fit allows the pouring in of
the mixture. After standing and draining the lower phase one need only place a
finger over that hole to severely restrict the flow , concluding by just pressing
the spigot against the bench top to close it.
Treating filter material to serve as a diaphragm in electrolysis separation is an area
wanting of experiment and development. The durability of the substrate is what
determines the limits of it's use. Paper is cellulose and must be regarded as such
in contemplating an intended application. There are other materials with attributes
more suited to harsh use , for example polyethylene ' paper '. See Tyvek here _
http://en.wikipedia.org/wiki/Tyvek
If you wonder what Tyvek is like , inspect the Express Mail envelope at the U.S. Post office
http://upload.wikimedia.org/wikipedia/en/thumb/f/f6/TyvekExp...
No reason why it could , pore size is in the micron range , an azeotrope requires
molecular scale openings to discriminate.
[Edited on 10-11-2010 by franklyn]
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scientician
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Sorry to keep digging this old shit up. I worked on this last night, both with a 25% solution of water in ethanol (everclear, bitches!) and some 5%
vinegar.
The everclear just slipped through, albeit slowly. I was disappoint.
The vinegar seemed to be working well. I observed the same thing as peach, wondering if I hadn't ruined the seams. On closer inspection, I realized
I was using the pre-fluted, seamless style of coffee filter.
It seems that if you crease or even bend the paper after the spray has dried, water can get through.
Not being one to be dissuaded, I whipped out my AeroPress coffee thinger (a great buy for the home scientist as a replacement for vacuum filtration in
certain circumstances, IMHO. Have a butcher's; http://aerobie.com/products/aeropress.htm) I prepared one of the 2" diameter circular paper filters and dried it in the oven at 250 F.
Excitedly, I set it up to collect pure GLACIAL ACETIC ACID and poured some of my freeze distilled vinegar in. It promptly sat there and did nothing
at all, smiling at me the whole time. I may as well have poured it into a cup.
After I finished throwing some of my glassware at the wall, I sat down and thought about it, and realized that although paper might not be ideal,
there are these nylon, re-usable coffee filter thingers that might really work well. (The spray is designed for cloth, after all.) I'm going to play
with this a while, and report back how it goes.
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chemrox
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what is phase separator paper? https://www.zoro.com/whatman-phase-separator-paper-150cm-pk1...
Is it only for vapor phase water removal and how would that be done? What is the use generally speaking? i.e. how would it be applied? I assume it's a
fairly useful item as it is a Whatman product sold in packages. Anyway, "Zoro" is worth looking into. Some really high prices other reasonable and a
wide range of products. Hint: use the backspace key rather than backing up on the listed pathways.
[Edited on 29-3-2016 by chemrox]
"When you let the dumbasses vote you end up with populism followed by autocracy and getting back is a bitch." Plato (sort of)
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Dr.Bob
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The phase separator papers are great for using in place of sep funnels, especially for small amounts. They work well in whatman type filter rigs,
but they can be used inside a syringe barrel or other tube to allow you to quickly filter off DCM from water solutions. You can put a solution in a
syringe, and add a squirt of DCM, which will have enough time to extract some material and then drip through. Over a few washes, you can extract a
solution several times, and even do it in parallel or with an automated system. That is what makes them better than sep funnels. I have seen
manifolds that do 8, 12, or 24 samples at once.
If some people want to test the Whatman ones out, I have a few boxes of them I found recently, I can provide a few samples or sell a box of them. I
don't remember the exact sizes, but I think they are 90, 110, or 150 mm in diameter. I might even have some other forms of them, but I have no idea
exactly what box they were in.
Bob
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RogueRose
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Can anyone explain what these papers are? The video shows an error when I try to view it.
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Dr.Bob
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They are a type of filter paper which has been treated to be hydrophobic, aka "water-hating". So water beads up on them, just like it would on
chloroform or when mixed with grease. But hydrocarbons can still wet them, so they flow through. It is almost like a cell membrane, keeping water
in, but letting some molecules pass through passively. They will only separate immiscible liquids, not miscible ones, like ethanol and water.
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gatosgr
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Vinylidene fluoride is hydrophobic, what is the process of the OP?
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Dr.Bob
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| Quote: Originally posted by Mister Junk Pile | Some water repellent products use fluorinated surfactants to induce hydrophobicity. It is likely that these would be much more resistant to being
dissolved by organics than regular siloxanes. In fact, at least one perfluoro acid salt is almost completely insoluble in at least 20 different types
of organic solvents. This would be the potassium salt of perfluorooctanesulfonic acid.
If the acid could somehow be deposited on the paper as the potassium salt I believe it would last a VERY long time. I suspect the paper would begin
to fall apart before that compound fully dissolved regardless of what solvent was passed through it. |
Some of the hydrophobic frits and papers are or were made from perfluoroacids or sulfonic acids, most were actually activated as the acid chloride and
then reacted with the paper, the hydroxyls in the cellulose react with the acid chloride to covalently attach the perfluoro material. For a while,
there was a big fad in chemistry to use perfluoro materials for that. It has since died down a bit, due to costs and being overhyped. But the papers
work well for some uses.
Waterless urinals also use a similar principle but different membrane to let urine flow through, but not let sewer gasses flow back.
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Firmware21
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Not working for me ;(
Anyone got a link to the video ?
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chemrox
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was there a video somewhere? I didn't see one
"When you let the dumbasses vote you end up with populism followed by autocracy and getting back is a bitch." Plato (sort of)
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