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Author: Subject: How to clean a separatory funnel?
monolithic
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[*] posted on 19-5-2019 at 13:31
How to clean a separatory funnel?


After some use my once sparkling clean separatory funnel is dirty. I've disassembled the stopcock and cleaned the outside quite easily, but there's still residue on the inside. I've tried hot water, hot soapy water, acetone, ethyl acetate, dilute sulfuric acid, and NaCl in isopropyl alcohol. There's still a small surface layer of something on the inside that appears when the funnel is allowed to dry. I've considered some sort of base bath but I don't want to destroy the ground glass joints or the clearances on the stopcock. Are there any other tricks to cleaning this out? I'm aware of the powers of aqua regia and piranha solution, but I want to avoid those if at all possible.
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CobaltChloride
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[*] posted on 19-5-2019 at 13:41


I soak my glassware in a Na3PO4 bath with soap to clean it when I encounter difficult stains. Works very well. Na3PO4 is strong enough of a base to hydrolyze fats, but never damaged any ground glass joints. It also has the added benefit of not reacting with atmospheric CO2 unlike NaOH so the bath is stable indefinitely. Near my sink I have a 13l bucket to which i added a kilo of commercial Na3PO4 and 9l of water along with ~500ml of concentrated universal detergent.

Another option I really like is applying some non scratch scouring powder with bleach, wetting it with a bit of warm tap water and then either swirling the wet paste around or rubbing it on the glassware depending on whether I can get my hands into that particular spot. This seems to work wonderfully for most gunk.

The gunk might also be calcium salts which don't easily dissolve in dilute H2SO4 so you could also try dilute HCl.
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TGSpecialist1
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[*] posted on 19-5-2019 at 13:52


Fenton's reagent - first dissolve 0,2 g of FeSO4 in 20 ml of boiling water, add 20 ml of 30% H2O2 then quickly transfer the mixture into a funnel. Turn on the vacuum for a second to let it seep into the sinter and stand back (that sounds worse than it is). When the reaction is complete wash the sinter with dilute H2SO4.
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monolithic
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[*] posted on 19-5-2019 at 13:53


Quote: Originally posted by CobaltChloride  
I soak my glassware in a Na3PO4 bath with soap to clean it when I encounter difficult stains. Works very well. Na3PO4 is strong enough of a base to hydrolyze fats, but never damaged any ground glass joints. It also has the added benefit of not reacting with atmospheric CO2 unlike NaOH so the bath is stable indefinitely. Near my sink I have a 13l bucket to which i added a kilo of commercial Na3PO4 and 9l of water along with ~500ml of concentrated universal detergent.

Another option I really like is applying some non scratch scouring powder with bleach, wetting it with a bit of warm tap water and then either swirling the wet paste around or rubbing it on the glassware depending on whether I can get my hands into that particular spot. This seems to work wonderfully for most gunk.

The gunk might also be calcium salts which don't easily dissolve in dilute H2SO4 so you could also try dilute HCl.


That's a great idea, I didn't consider that they might be calcium salt deposits. :)
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[*] posted on 19-5-2019 at 14:36


Best is always elbow grease and a bottle brush. Second best is methanol and rock salt and swirling it around vigorously to scrub the surface. If you're worried about the joint, grease it and put it in place then put a septum or something in the bottom joint or put it into a bucket and fill the whole thing so the grease protects the joint.




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monolithic
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[*] posted on 19-5-2019 at 15:25


Quote: Originally posted by BromicAcid  
Best is always elbow grease and a bottle brush. Second best is methanol and rock salt and swirling it around vigorously to scrub the surface. If you're worried about the joint, grease it and put it in place then put a septum or something in the bottom joint or put it into a bucket and fill the whole thing so the grease protects the joint.


Does anyone make a specialty separatory funnel brush -- I'm not seeing any? Mechanical cleaning would be effective, I think, but there's no way to reach the afflicted area of the flask with a bent conventional flask brush. I tried table salt and IPA, maybe rock salt would be a better choice if dilute HCl doesn't work.
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DavidJR
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[*] posted on 19-5-2019 at 15:45


Just base bath it. I routinely use a base bath for all of my glassware (except sintered filters and volumetric stuff) and it's honestly not going to kill your joints/stopcocks. And I am lazy and forget about stuff so sometimes glassware will sit in the base bath for a week.
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[*] posted on 19-5-2019 at 19:48


These are not the brushes I use but they are similar, being wire in the center you can bend them so they angle against the wall to clean the inside of flasks / funnels / etc.

https://www.amazon.com/Bottle-Cleaning-Bristles-Radial-Chemi...




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[*] posted on 19-5-2019 at 20:13


If the flow control is ok and everything that you throw at it failed to remove the stain,
then it is unlikely that the stain will significantly contaminate future usage.
So you have to balance cosmetic beauty against risk of damage.




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monolithic
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[*] posted on 20-5-2019 at 03:44


Quote: Originally posted by Sulaiman  
If the flow control is ok and everything that you throw at it failed to remove the stain,
then it is unlikely that the stain will significantly contaminate future usage.
So you have to balance cosmetic beauty against risk of damage.


That's a good point. Dilute HCl appears to get most of it off, there's only a very small amount left on the inside, which I can tolerate. I'll be sure to write down the other suggestions in this thread, if needed in the future. Thanks everyone.
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[*] posted on 20-5-2019 at 04:04


HCL or windex (nh3 and alcohol), or bleach straight from the bottle then get a chopstick from the sushi restaurant and stick a scourer or paper towels on the end of it and scrub or hot nitric acid or hot concentrated sulphuric acid.i believe chromic acid is also used somehow to clean glass if none of these work its too hard.
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[*] posted on 20-5-2019 at 15:10


EtOH and HNO3 mix works well also for stubborn cleaning. It produces copious amounts of NO2 so be careful.



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[*] posted on 16-6-2019 at 13:38


When I have some dirty glassware that seems impossible to clean, I always try with aqua regia, and if it fails, with chromic mixture.
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[*] posted on 16-6-2019 at 14:05


I've had good luck with deposits by using commercial lime scale cleaners, like Lime Away (US product).

I believe they are based on sulfamic acid.

This works for most of the white deposits on used glassware i run into.





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[*] posted on 16-6-2019 at 15:44


Fuming HCl and fuming HNO3 work well by themselves for organics and limescale, and you only need to put a small bit in the funnel or flask, cap it and put it in a hood (or outside), and rinse it when it has done it's work.

BromicAcid's tip about masking the ground glass joint with grease is a good one. Someone mentioned that they leave their glass in a base bath for a week without consequence, idk what kind of base bath they use, but I would advise against that.

I use absolute etOH and 90% KOH, and if I leave it in a flask for 2 days I get visible pitting.
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[*] posted on 17-6-2019 at 06:08


You could try hot sodium persulfate + 254 nm UV (from a germicidal lamp). It cleans glass very well and makes a water film.
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[*] posted on 16-10-2019 at 10:09


in some place I read a guy mixing nitric and hydrofluoric and this make the glass clear like pure air but I lost the link message???
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[*] posted on 16-10-2019 at 11:36


HF is an excellent solution to getting rid of those bits of glass that are clinging onto dirt :)

[Edited on 16-10-2019 by RedDwarf]
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[*] posted on 16-10-2019 at 12:14


Hot hydrogen peroxide (both diluted and concentrated) is a good option to destroy organic traces from glassware.



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[*] posted on 16-10-2019 at 17:45


Sulfamic acid can sometimes be found OTC, as grout cleaner in home improvement stores. Also, commercial food service stores sometimes have it, for use as a haze remover for coffee decanters, which is essentially what you want it for, too.



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