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Author: Subject: How to filter oily sludge/slurry ?
CycloRook
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[*] posted on 3-3-2022 at 15:17
How to filter oily sludge/slurry ?


I have done a reaction and I have a product/solvent layer and a water/salt layer. There is a suspension of sludge and salt that my oily product is partially trapped in.

I'm using vacuum filtration with a sintered glass Funnel.

I've hit one full 350ml Funnel for over an hour and it's not quite done.

Does anyone know a better method for filtering hard to filter products?

Thanks

[Edited on 3-3-2022 by cycloknight19]

20220303_181726.jpg - 3.5MB

[Edited on 3-3-2022 by cycloknight19]

20220303_181745.jpg - 3.5MB
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CycloRook
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[*] posted on 3-3-2022 at 15:19


As you can see the top layer is sludge with oil mixes in bottom is I believe water.
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Rainwater
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[*] posted on 4-3-2022 at 13:52


Pressure filtering works better than vacuum filtering. It's more dangerous too.

Vacuum filtering is the equivalent of ~14psi or 1 atm

I use an air compressor filter. Just secure a piece of filter paper over the factory filter with a hose clamp.

I clean and dehydrate my used vacuum pump oil by salting out the water with dry mgso4, then decanting the top layer into 2 gallon air tank.

Then i hook everything up to the air compressor and push 90 pounds on it.




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Antiswat
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[*] posted on 10-3-2022 at 07:25


ive heard adding zeolite or similar mineral powders can help it, yesterday i filtered about 300mL of cobalt hydroxide sludge, it wouldnt go through my lab filter papers designated for filtration but using cotton pads, the round ones women use for makeup works a lot better, but they do have a limit, so you wanna replace it every now and then and work with a small amount of liquid at a time
if you can by any chance concentrate down the sludge that would maybe be a great idea
as reference filtering aluminium hydroxide is a lost cause, rather you just evaporate it to dryness where the gel will then solidify and once put back into water it will just barely gel up
otherwise you may wanna look at precipitating out the mess in a different way, the slower the reaction the bigger the "crystals", ive produced workable piperine sludge by slowly dripping water into an ethanolic solution of piperine i achieved from pepper
i have also seen using more concentrated reagents produced a less spongy and more dense precipitate




~25 drops = 1mL @dH2O viscocity - STP
Truth is ever growing - but without context theres barely any such.

https://en.wikipedia.org/wiki/Solubility_table
http://www.trimen.pl/witek/calculators/stezenia.html
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CycloRook
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[*] posted on 10-3-2022 at 07:35


Quote: Originally posted by Antiswat  
ive heard adding zeolite or similar mineral powders can help it, yesterday i filtered about 300mL of cobalt hydroxide sludge, it wouldnt go through my lab filter papers designated for filtration but using cotton pads, the round ones women use for makeup works a lot better, but they do have a limit, so you wanna replace it every now and then and work with a small amount of liquid at a time
if you can by any chance concentrate down the sludge that would maybe be a great idea
as reference filtering aluminium hydroxide is a lost cause, rather you just evaporate it to dryness where the gel will then solidify and once put back into water it will just barely gel up
otherwise you may wanna look at precipitating out the mess in a different way, the slower the reaction the bigger the "crystals", ive produced workable piperine sludge by slowly dripping water into an ethanolic solution of piperine i achieved from pepper
i have also seen using more concentrated reagents produced a less spongy and more dense precipitate
I lowered the temp and it definitely worked better I was actually able to separate everything. It was still a nightmare and I'm pretty sure I lost a lot of product to the magnesium bromide crystals.

I'm thinking to get a bigger funnel with more surface area so as to not build a giant slurry cake. It was dry at the bottom of the funnel but the top was full of wet slurry.
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zed
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[*] posted on 21-3-2022 at 21:34


As previously discussed; is your product temperature sensitive? If not, you might simply be able. to steam distill it out of the muck.

Another possible angle is to produce larger crystals of inorganics, is not via lower temperatures but by higher temperature neutralization.

The logic being this.... The faster crystals are formed, the smaller they are. Crystals because of their insolubility, tend to be forced out of solution more quickly, when reactions take place cold. In near boiling solutions, because of higher heat, inorganic components are more soluble and therefore crystalize out more slowly... Thereby yielding larger crystals, that are more filterable.

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BromicAcid
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[*] posted on 22-3-2022 at 05:41


@Rainwater - those frits are usually not designed for massive pressures. In practice we use frits like that all the time at my work, they are the sealed body type that allows you to pressurize them and keep things under nitrogen atmosphere. There have been instances with larger frits when putting ~5 PSIG nitrogen on the top and full vacuum on the bottom that they have catastrophically failed. Point being that just mainlining the air pressure from a air pump might - at best - blow out your sintered glass, and at worst explode your setup.



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Rainwater
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[*] posted on 22-3-2022 at 14:12


Sorry. I was not referring to putting pressure on glassware.
home depot link
This is a stainless steel fitting with acrilic housing.
50 micron sand filter
90 psi max
1in ntp threads.

The container may not be compatible with all solvents.
Ive seen glass containers aswell.




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Antiswat
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[*] posted on 4-6-2022 at 06:07


OKAY- im gonna give my silly input as i just had to deal with some piece of shit hydroxide ppt and lord knows what. impossible to vacuum filter this demonic stuff, no matter what kinda filtering medium i use
however adding some water and going for good old regular filtration over a large pot with some cloth clamped at 4 points does the trick- i had to resort to this back when i was purifying chromate through copper chromate precipitation (sludge hell)

simply put: oldschool. letting it run through properly first time will ensure you get most of the liquid out, adding 3x the volume of water to the filter cake makes the stuff come through with a 3x dilution rate




~25 drops = 1mL @dH2O viscocity - STP
Truth is ever growing - but without context theres barely any such.

https://en.wikipedia.org/wiki/Solubility_table
http://www.trimen.pl/witek/calculators/stezenia.html
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Sulaiman
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[*] posted on 4-6-2022 at 07:56


Is there a low bp solvent for the oil?
(eg liquid butane from lighter refill canister, ethanol, acetone,.. something should work)
Use excess solvent, allow sludge to settle, decant into filter, remove or recover solvent etc. ?




CAUTION : Hobby Chemist, not Professional or even Amateur
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