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Author: Subject: Cleaning of various ''materials''
Antiswat
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[*] posted on 11-5-2013 at 12:01
Cleaning of various ''materials''


I thought it would be a good idea to have a thread where we can discuss/contribute with different 'tricks' or facts about different kinds of substances/surfaces.
As im pretty sure all of us on here does chemistry that will ofcourse involve cleaning up afterwards, in a such way theres still some 'laboratory' left (;

So lets see...


Glassware:
Basically for any type of stains i would say hydroxides, highly concentrated solutions, preferably hot.
This will or should remove a tiny layer depending on how long time its cooked in the container, if you have say.. carbon on the sides of a container the glass its attached to's surface will be etched away, still this is just the absolute surface and not the entire glass.


Spills:
I happen to have a wooden table of some sort coated with something, anyhow sometimes all kinds of things decides to sink down into it, including some nickel tetraammine just lately, leaving a huge purple spot, anyhow i got partially rid of it with a new 'method' i discovered by somewhat accident while grinding up CuO in my heavily Fe2O3 stained mortar.

The CuO was dominating all the Fe2O3, when i added HCl it instantly turned into CuCl2 and somehow the Fe2O3 was removed also, this can be done aswell with tables as long as youre not able to directly soak them in it, which could leave some CuCl2 in it, impossible to get away.

I havent gotten 100% rid of the tetraammine stain tho, but i started with conc. ammonia, then rubbed CuO on it with great force (very little wettened CuO) as in with a bottlecap.

The rest is pretty selfexplanatory, tho i did one more thing:
i raised the heat while the CuCl2 and HCl was on there with aluminium foil, this reacts vigourously and gets hot very fast, and ofcourse hydrogen is formed.

H2O2 seemed as a good idea, somehow it turned the nearly invisible stain into green (i gave up trying to understand what happened at this point) whereafter i needed a few CuO washes to make it nearly invisible again.

Sandpaper is usually good, especially very fine sandpaper thats worn out for sinks and such.

For copper i guess you could try vinegar + salt, works surprisingly well to clean up copper based coins.

For a carpet im not really sure of how to do it, i guess you just wanna neutralize if possible, then soak it all in water and drag the liquid out using paper, perhaps if its insoluble first try with vacuum cleaner then try to dissolve it and remove it while dissolved.

For KMnO4, im not sure how useful this would be but, to turn KMnO4 almost colourless you could try adding NaOH and sugar solution to turn it more transparent, if you want to avoid using gloves this could make sure you dont have contact with KMnO4 but rather some hydroxides, abit of sugar and MnO2.


Yourself as in your hands:
Theres a few things infamous for making some pretty neat stains on yourself being KMnO4 and ofcourse MnO2.

KMnO4 is said to be more easily removed with use of lemon juice (i guess citric acid for higher efficiency)

For MnO2 you should be able to use NaHSO3 or concentrated HCl, if this is succesful you can smell SO2 coming off with the NaHSO3, so you know that something is happening at least.


About stains on objects i havent actually tried removing MnO2 stains with my CuO method, but its plausible to work aswell, of what i see it has great potential and making or buying CuO isnt that hard.
It will also allow for speeding it up with adding a metal thats reactive to HCl.

Potentially for carbon stains you could try heating up some nitrate, but problem would be if you heated the glass (assuming its glass) too fast resulting in it breaking apart.

Give in with ideas





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[*] posted on 11-5-2013 at 12:31


This one should be sticky.

I have a similar method to your CuO/HCl method. It is used also industrially in some processes, AFAIK.
You can try, for example: You do not have any HCl yet and you have brown stains from KMnO4 inside your glassware. Just take some dilute H2SO4 (which can not remove it by itself) and add some Zn or ZnSO4. Heat it up and the stains are gone. It works by displacing the zinc in ZnSO4 by Mn, which goes into solution, and the formed ZnO dissolves again. So it is a catalyst.




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[*] posted on 12-5-2013 at 05:36


oh yes.. stains from KMnO4 as in MnO2.. i might try that, but im not sure what i should use for it tho.. glass would be too easy i think..
ill definately try it.. but ZnO reacts pretty fast with acids, so if we cover the surface of something with that, which is stained its likely to act the same way as with CuO




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[*] posted on 12-5-2013 at 06:32


I made this thread sticky. Cleaning (and more general, working cleanly) is an important aspect of practical chemistry. It is good to have ideas about this collected in a single thread and ready to be read. I would like all contributors to adhere to some practical rules:
- Do not post speculative and vague procedures in this thread, let's keep things practical and useful.
- If dangerous cleaning procedures are posted, then clearly warn about the dangers and clearly specify why such a dangerous procedure should be used. An example which comes to my mind is the use of piranha solution in some cleanup procedures, or the use of hot chromic acid in sulphuric acid.




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[*] posted on 12-5-2013 at 06:43


Glassware containing char/large chunks of carbonized organics stuck to it can be cleaned cheaply and safely with a boiling mixture of sodium hypochlorite (bleach is alright, but more concentrated pool grade stuff works better) and vinegar. I found that this softens the rock hard char so that it can be removed easily by scraping or might even pop off by itself. It takes some time though, but is much safer (cheaper too!) than using something like piranha solution or a mix of chromic and sulfuric acids, although it does smell a bit and can produce small amounts of chlorine gas (so this should be done outside).

Oxalic acid easily removes traces of iron oxides on glassware as well as on metal.
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[*] posted on 15-5-2013 at 01:35


Quote: Originally posted by weiming1998  
Glassware containing char/large chunks of carbonized organics stuck to it can be cleaned cheaply and safely with a boiling mixture of sodium hypochlorite (bleach is alright, but more concentrated pool grade stuff works better) and vinegar. I found that this softens the rock hard char so that it can be removed easily by scraping or might even pop off by itself. It takes some time though, but is much safer (cheaper too!) than using something like piranha solution or a mix of chromic and sulfuric acids, although it does smell a bit and can produce small amounts of chlorine gas (so this should be done outside).

Oxalic acid easily removes traces of iron oxides on glassware as well as on metal.


about NaClO concentration, i have been able to not only make NaClO extremely concentrated, but actually still being NaClO and not NaCl + NaClO3 EVEN after i boiled it down into a solid several times.
several times i had to repeat this in order to get NaClO3, or well this was infact KClO but surely very same properties as NaClO
in short, with careful heating NaClO should be possible to concentrate just as with H2O2 (:

thanks for making it a sticky, first realise now why i didnt find the thread looking under the non-stickies :D




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[*] posted on 15-5-2013 at 03:16


Quote: Originally posted by Antiswat  
oh yes.. stains from KMnO4 as in MnO2..
A very good way of removing such brown stains is rinsing with an acidified solution of sodium sulfite or bisulfite. Stained glass becomes clear again at once. Equally well works a solution of 1% H2O2 in dilute acid. Both solutions reduce the brown MnO2 to colorless Mn(2+), which goes into solution at once.



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[*] posted on 15-5-2013 at 06:10


oh yes acidified H2O2
my hands are pretty well covered in MnO2 speaking about it.. i might try that..
tried 30% HCl and solid NaHSO3 rubbed on my hands then small amounts of water added
even both at once.. forgot NaHSO3 and HCl reacts :s

another one giving the reason for my MnO2 covered hands is water, oxalic acid and conc. H2SO4
on turning MnO2 into MnSO4 for then MnCO3 and finally Mn(NO3)2 you can use 300 mL water, 30g oxalic acid and 12 mL 98% H2SO4
the H2SO4 becomes fairly dilute so i doubt this would have much of a danger to your hands unless if you fall asleep with your hands in the solution
what happens is the oxalic acid first reacts with the MnO2 to reduce it, whereafter the H2SO4 is capable of reacting with it




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[*] posted on 15-5-2013 at 06:58


Quote: Originally posted by weiming1998  
Glassware containing char/large chunks of carbonized organics stuck to it can be cleaned cheaply and safely with a boiling mixture of sodium hypochlorite (bleach is alright, but more concentrated pool grade stuff works better) and vinegar


Found what is likely my last surviving piece of lab glassware, a beaker with burned down black gunk in it...It was 10 years ago I don't remember what but something boiled dry on me I think. Gonna try this I think.
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[*] posted on 16-5-2013 at 05:42


Quote: Originally posted by weiming1998  
Oxalic acid easily removes traces of iron oxides on glassware as well as on metal.


I have an anecdote I'd like to add to this. A friend of mine was etching circuit boards on his back porch and ended up with a lot of ferric chloride stains on the concrete floor. He tried my oxalic acid on that, but it did not work to clear it up. The stain would seemingly disappear, but when the deck was rinsed it would show up again. I think concrete is too porous for much of anything to work well. He might have to resort to using my hydrochloric acid for the purpose it was intended - etching concrete!


I've also found that minor iron stains on glassware can be removed by a soak in hardware-store-grade HCl over a day or two.
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[*] posted on 16-5-2013 at 11:09


Quote: Originally posted by MrHomeScientist  
Quote: Originally posted by weiming1998  
Oxalic acid easily removes traces of iron oxides on glassware as well as on metal.


I have an anecdote I'd like to add to this. A friend of mine was etching circuit boards on his back porch and ended up with a lot of ferric chloride stains on the concrete floor. He tried my oxalic acid on that, but it did not work to clear it up. The stain would seemingly disappear, but when the deck was rinsed it would show up again. I think concrete is too porous for much of anything to work well. He might have to resort to using my hydrochloric acid for the purpose it was intended - etching concrete!


I've also found that minor iron stains on glassware can be removed by a soak in hardware-store-grade HCl over a day or two.


i think your mate may have a serious problem.. tell him to cover it up (:
as of what i have seen FeCl3 goes into Fe2O3 over time and thats really a bitch to attempt removing.. i got a table stained with that stuff all over, to my luck its a smooth surface unlike concrete, where i can then use CaO + HCl method on it..
careful HCl etching (dilute?) and then sudden neutralization when wanted result is acquired might be the thing for him..
dont know how smooth concrete were talking about here tho

that last sentence sounded hilarious to me, no idea how tho..




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[*] posted on 16-5-2013 at 21:43


I'd like to add the following: I work with iodine a fair bit, and consequently my clothes sometimes get nasty, otherwise unwashable brown stains. I was told to try dilute sodium thiosulfate. It worked wonders, but only if you treat the stain right after it happens.
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[*] posted on 1-6-2013 at 03:49


on a sitenote process stated by Adas can potentially with 37% H2SO4 and 900 mesh zinc powder evolve SO3 so have some ammonia ready (=
you can recognize this gas by breathing through your mouth and if you get the feeling of a bus covered in P80 sandpaper sliding down your throat, then theres SO3 in the air ^^




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[*] posted on 10-6-2013 at 21:51


I got copper oxide decomposed from a copper salt in test tube. It solidified to the tube, don't want to waste tubes :p .. any ideas ?



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[*] posted on 10-6-2013 at 21:56


Any acid should work to get rid of the copper oxide - I'll recommend sulfuric or hydrochloric (given the availibility of the former). Vinegar can also be used.

I found that to remove a tough, brownish-black stain on one of my RBF's, stoppering it with some soap, water and a quarter-flask's worth of sand, followed by a good, hard shake for 2-3 minutes works wonders.




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[*] posted on 6-7-2013 at 15:13


indeed, idk about acetic acid but HCl works straight away
green colour and.. you could add some aluminium to it and then drop HCl on, the heat will raise the reaction temperature

can you have test-tube-phobia anyhow?
dont want testtubes, surely gonna end up filling up a test tube with solid carbon and thats kind hard to remove




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[*] posted on 6-7-2013 at 15:45


Quote: Originally posted by Antiswat  
Yourself as in your hands:
Theres a few things infamous for making some pretty neat stains on yourself being KMnO4 and ofcourse MnO2.
KMnO4 is said to be more easily removed with use of lemon juice (i guess citric acid for higher efficiency)

Quote:
Finally the outer layer of skin might be removed with a 4% solution of potassium permanganate. The purple stain from the permanganate would be removed with 4% sodium bisulfite.


[Edited on 14.1.14 by bfesser]




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[*] posted on 6-7-2013 at 17:41


Today I was going to thread/tap a thick piece of stainless steel tubing and decided to anneal it first by heating it to a red heat and letting it cool slowly. As the metal was being blowtorched, it started to discolor greatly, moreso apparent a little distance away from the red hot surface with a few colorful hues, as well as some tarnished ugly shades. After threading the tubing, I didn't like the oxidized patina at all. So I remembered Barkeeper's Friend which contains oxalic acid and it almost removed every single trace of heat damage with a soft scrub sponge using the finely woven abrasive side. If I'd put in more effort it might have restored entirely like new.
Bar Keeper's Friend "Once tried, always used". Good slogan.
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[*] posted on 7-7-2013 at 18:13


Is it OK to soak standard taper glassware in concentrated NaOH/EtOH mixture, or will it ruin the ground glass joints? I thought I'd read that before but I couldn't manage to find any threads mentioning a problem...
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[*] posted on 9-7-2013 at 02:17


i wont reply to everything as it would just get exaggerative
a question however..
bob800: i dont think you want fine glasspieces to be in contact with NaOH at all, really.
BUT however if you manage to keep the 'flow' of NaOH solution very even i dont see much could happen
whats it for anyways?
infact the ground glass joints could potentiall be ruined by the NaOH, might or might not
im not sure.. if you have a broken piece of glass joint soak it in the solution and see




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[*] posted on 9-7-2013 at 17:27


Quote: Originally posted by bob800  
will it ruin the ground glass joints?


The quick answer is yes, it will ruin it. However, for short periods of time (20-60 minutes) it will not do any noticeable damage.

In my lab, we scrub and dissolve almost all the junk on the glassware and then place them in the "base bath" for rather short periods of time. We do this for any ground glass piece, so you could say this is a well tested method. If you forget it in the bath overnight, you may have problems, but I have accidentally done it before with heavy walled round bottoms and no noticeable damage has befallen them.




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[*] posted on 9-7-2013 at 18:03


Omnia prius dicta sunt!

[corrected from "dictum est"]

[Edited on 7/15/13 by bfesser]




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[*] posted on 9-7-2013 at 19:07


Well, guess it's about time to close this thread? I like the compilation, unless you are grabbing posts from in here for your new sticky thread :P



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[*] posted on 14-7-2013 at 09:46


I see no reason to close it. I just wanted to point out that there's a lot already here for anyone who knows how to find it. There's always room for addition.



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[*] posted on 15-7-2013 at 11:51


I've had trouble with silver stains on my lavatory. I don't have a sink in my (garage) lab and so have to use the bathroom lavatory. The stains seem to come from traces of silver nitrate, that perhaps via the chloride eventually turn into silver. Scrubbing does not help. I would use nitric acid, except it would attack the metal fixtures around the drain. I've been thinking of piling up sodium carbonate in a mound around the drain, to protect it when the nitric acid drips down, and then scrubbing the silver stains with the nitric. If I do this, I will rinse in distilled water, to avoid chloride formation and to flush all the silver down. Any advice for alternatives would be appreciated.

bfesser, I think it should be omnia prius dicta sunt.




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