These darn surfactants! Many household items contain interesting chemicals. I used a lot of experiments trying to separate them. But these damn
gelling agents, this foam... Wasted the entire stock of hydrochloric acid trying to neutralize the soap (resulting in some brown waxy grease that I
couldn't separate without a separating funnel), had to cough up a whole new batch of hydrochloric.
It seems, distilling azeotropic hydrocloric acid from unconcentrated Bat and table salt on a Liebig is a lot easier than dissolving the goddamn gas.
And sorry aga, no photos of my distilling setup at work. I've lost the battery for my phone-slash-camera.
[Edited on 9-12-2015 by ave369]chemrox - 9-12-2015 at 12:06
5 ml Con HCl, 15 g MgSO4 (anhydrous), 40 ml ether. Makes an ethereal HCl solution for crystallizing amines aga - 9-12-2015 at 12:32
What I observed with oil + water + soap, when stirred, the oil layer then became filled with tiny bubbles. It appeared to be foamy, the top oil layer.
Whereas the water layer looked a tiny tiny bit murkier.
I know the hydrophobic tale goes for the non polar molecule, and the hydrophilic end of the surfactant goes for the polar molecules, but that is about
it.
If oil and soap and water were mixed, how would the surfactant be removed? Yttrium2 - 10-12-2015 at 10:51
Bump, I posted some pictures.
Why does the soap make the oil layer foamy, and how can the soap be removedOzone - 10-12-2015 at 16:20
Not foam. Emulsion. If you added more soap, eventually the phases would become one--oil/soap micelles in water.
Getting rid of soap is a pain because it will also emulsify, say, any extraction solvent you might try and use. pH helps. And, it depends on the
surfactant type. Soap is anionic and could be treated with calcium to yield the (relatively) insoluble calcium (say) di-dodecyl sulfate. Cationic
surfactants are relatively rare. Anionics and cationics might be removed with the appropriate ion exchange resin. Non-ionics (e.g.
TWEENs/polysorbates, PEGs) are common; amphoterics, not so much, but with either, you are especially screwed.
Also, the MBAS (methylene blue active substance) test for surfactants (especially anionics) is an easy way to see how much soap you have in there: https://en.wikipedia.org/wiki/MBAS_assay
It's ugly, but it's cool.
O3
[Edited on 11-12-2015 by Ozone]
non-ionics
DirtMcGirt - 11-12-2015 at 11:10
for non-ionics some possibilities are H2O2 and UV (sodium percarbonate and sun, maybe iron per Fenton reaction), Lipase enzymes (digestive aids,
natural septic cleaner) and sonification (ultrasonic tank). You would have to worry what they would do to your target molecule though. Possibly some
fine filtration to mechanically filter out the long chain surfactants. Yttrium2 - 11-12-2015 at 15:51
Truth is, is that I haven't been interested in surfactants for too long. They have interested me though, and confuse. This is why It is a love hate
relationship,I think the love wins though. I'm not sure how much of an application they have, if it is limited to soaps, or if they can do marvelous
marvelous things. It is interesting how they change what is expected, causing unlike substance to mix. Breaking simple rules, making a mystery out of
something expectedYttrium2 - 11-12-2015 at 16:07
Can someone explain the Fenton reaction and how that could remove or isolate a surfactant? What about ion exchange chromatography? I'm mot sure if I'm
getting ahead of myself, perhaps I should listen to the words that were given to me not so long ago...Ozone - 11-12-2015 at 16:42
No. Fenton's reagent involves the disproportionation reaction of peroxide catalyzed by ferrous or ferric ions to yield hydroxyl and peroxyl radicals,
respectively (REDOX cycling). The hydroxyl radical is, IIRC, second only to fluorine in terms of oxidative power. If you successfully get this going
(and maintain it via addition of peroxide), it will attack and destroy just about anything organic in your mixture. Poof. Overkill.
Sonics can and will destroy organic molecules. Macromolecules are particularly vulnerable. But, they don't go poof, you just get smaller pieces.
How come the Fenton reaction I saw was just vitamin c water and a piece of iron, no peroxide added iircave369 - 12-12-2015 at 00:50
I think the Fenton reaction is the right thing to do to free phoshporic acid from surfactant prison in one of my household chems. But with oxalic
acid... thinks are bleakier. How do I liberate oxalic acid from a soapy gel?
Concurred. Experiments by others have shown that UV/H202 are nonselective in their destruction of organic molecules. However, i always wondered if
proper amounts of H202 and UV could be tailored to oxidize a target molecule considering redox potentials of whatever molecules are in solution.
However, any experiment theBrooklynZoo has tried with sodium percarbonate and UV has yielded total destruction of interested organic molecule, along
with most of the others in the solution.
The proper lipase enzyme for target degradation seems more promising.
I have also seem some experiments by others who have used chlorinated solvents and activated charcoal with some success for nonionics. Ozone - 12-12-2015 at 10:09
I've thought about this in the past (Fenton--photo-Fenton is another story). It is almost impossible to control, even with careful addition. And, you
will destroy some of your desired product, even if it's more resilient than the contaminating molecules. It's statistically inevitable with
non-selective oxidants like this.
You need a more selective oxidant. Toward this, if you are to continue this line of thinking, I'd try pH buffering. You may be able to limit how far
it goes (and how selective it is), that way. You could also try to get the iron to relax a bit by ligating (complexes with phenanthroline, porphyrin,
salicylate, etc.) it first.
Peroxide behaves very differently when at acid, neutral or (whoa) alkaline pH. Iron solubility goes to shit around pH 4. I'd try and work within, or
around (say, by ligating the iron) those restrictions.
O3 ave369 - 13-12-2015 at 06:35
Today I've ran an experiment with a heavily surfactanted green gel containing oxalic acid. I ran it through a distillation apparatus with glycerine.
The dystillate was greenish in color, much less gelly than the original substance from the bottle and quite acidic. It had a smell similar to the
green sh* in the bottle, but weaker.
I have three verrsions of what happened.
1. The glycerol-oxalic acid reaction happened, and I got formic acid.
2. Foam from the green goop invaded the liebig and I got oxalic acid.
3. Both things happened at once.
Maybe upon distillation, the most gelly and goopy surfactants stay at home, and we get a less surfactant-invaded solution?Ozone - 13-12-2015 at 07:38
Well, it appears that whatever goop is in there does not interfere with the glycerol-oxalic acid reaction (which is pretty interesting to note), so
if you can contrive an entrainement separator of some sort (a long column would work, but would make the distillation slow and painful), you can just
distill the formic acid-water azeotrope.
Most surfactants are non-volatile, and so would concentrate in the pot. If your distillate was greenish, then you did have entrained stuff coming over
into your collector.
How are you determining if you have formic or oxalic acids? I'd run HPLC. Just curious, here.
But, if oxalic acid is what you want, you could dilute the cleaner, adjust to the pH to, say, 2, and put it through (or dump in a bunch) of weak base
anion exchange resin. Then, filter off the beads (it's best to run a column) and strip the organic acid off with 5% HCl, concentrate under vacuum
(rotavap works well) and crystallize it.
Alternatively, you could frag some sucrose with concentrated nitric acid.
O3unionised - 13-12-2015 at 09:57
Some surfactants can be stripped out with an ion exchange column if you are lucky.
Calcium formate is a lot more soluble in water than calcium oxalate.
