Posting this question here, as not sure where it should go.
After a messy o-toluidine reaction attempt there is a mass of iron chloride that seems to refuse to budge. 3rd day of soaking with hcl and well...its
still happily grunging up the glassware. poking at it loosens it a bit, but will admit to being a lazyass in this as there is a lot of it...
I was thinking of a piranha bath but after reading about it, the stuff worries me. what will its reaction be? violent reaction? explosion? a little
elf appearing to hand me a Darwin award with an evil cackle?
I am considering placing 35%h202 in the flask first, and then add h2so4..this outta clean it out but Id like suggestions first from the more
illuminated types..dilute the h2o2? the h2so4? anyone here clean this mess before?
ThanksThe_Davster - 8-8-2007 at 15:37
No experiance with that particuar reaction, but lots of experiance using pirhanna solution to clean stuff.
The proper method of using pirana is to add the conc. sulfuric first to the mess, and then slowly add cool 30-35% peroxide with stirring/swirling. I
have only ever had one incident with it, and that was when I had lots of organics in the mix, and added the peroxide too fast, and all that happened
was the mix boiling over and making lots of corrosive smoke that horribly oxidized the aluminum test tube rack in the fume hood. I can't imagine how
bad that would have been where there is less than good ventilation...
[Edited on 8-8-2007 by The_Davster]12AX7 - 8-8-2007 at 15:59
What form is it? Just FeCl3? That's soluble in water, and hydrolysis products like Fe(OH)3 are soluble in HCl. So there must be something about its
structure that's making it hard (embedded in rough surface; in a refractory Fe2O3 form; etc.?). Any description on that matter?
Timgreenyppols - 8-8-2007 at 17:44
Thanks Dav, I'll give it a try tomorrow.
12AX7, Beats me. I was surprised at the pain its become. Its black, nasty looking and stubborn. Thats all I know for sure.not_important - 8-8-2007 at 18:02
piranha solution is for organics, if what you have is mostly inorganic then it won't be that much more effective than just the H2SO4.
I'd try 10 to 20 percent HCl, reflux it gently for some time. Note that this concentration is below constant boiling, so it should not have too much
acid vapour coming off.
I assume you were running a reduction, but even in a reduction you can get oxidation if the mix overheats or the reducing agent gets walled off from
the rest of the reactants. So it is possible that you've some good organic gorp gluing things into a lump. But before I went after it with piranha,
I'd do the acid treatment, keep the acid, dry the flask, and reflux kerosene in it - about half full or a little more if that's what it takes to cover
the glorp. Let it cool a bit, pour the hot kerosene into a metal container, rinse the flask with a bit more hot kerosene. After the flask is cold, use
acetone or such to remove the last of the kerosene, let that solvent evaporate, and try refluxing the acid again.
Piranha is sort of the agent of last resort, I even use hot permanganate before goig to piranha when cleaning. As The_Davster said, add the peroxide
slowly, making sure that it's well mixed before adding more.Twospoons - 8-8-2007 at 18:08
IIRC iron stains are particularly hard to remove from glass, as the iron penetrates somewhat. You may be able to try this: http://www.freepatentsonline.com/6297208.html (fluoboric acid)The_Davster - 8-8-2007 at 18:17
Another gentler alternative to pirhanna, which I have used for iron oxide and manganese oxide stains on glassware is peroxide and HCl. I forgot about
this one in my earlier post, but it is what I prefer to use for removing metal oxides. I usually use it in dilute solution, around 15%HCl with 3%
peroxide added, its is not nearly as risky as pirhanna, and I am sure you could also give diluted sulfuric acid and peroxide a try first. No sense
breaking out the pirhanna for anything but the worst.Ozone - 8-8-2007 at 18:29
Are you sure that the stuff is all iron based (and not, say, some polymeric tar and iron-stuff)? This would make a great deal of difference in how it
behaves with a piranha.
ANy Fe 2+ you have in there will decompose your H2O2, catalytically (this can be a bit frisky yielding -OH , .OH radicals and Fe3+).
I'd try conc. HNO3, heat if necessary, with ventilation. This should oxidize and solvate most of the stuff. You may have a brown stain in your glass
forever, but at least the clumps should go away.
Cheers,
O3woelen - 8-8-2007 at 23:09
If I read this, I don't think it is only some inorganic iron stuff. Most likely you have a mix of organics and iron salts. I have been quite
succesfull in cleaning glassware with a mix of 25% HCl and some TCCA or calciumhypochlorite. This makes a strongly acidic chlorine-rich environment,
and such a mix destroys many organics fairly quickly. Some gentle heating may be necessary and occasional adding of some solid TCCA (or better:
calcium hypochlorite) during the process also helps. You need good ventilation though, a lot of chlorine will escape from the bottle.YT2095 - 9-8-2007 at 00:34
if it`s Just iron, then Oxalic acid works wonders greenyppols - 9-8-2007 at 02:59
Wow. Thanks for all the ideas everyone. Im gonna take notes on these and keep 'em around for when needed again.YT2095 - 9-8-2007 at 03:38
I had bad rust stained jeans the once, so bad it even made holes in places, gut a ball of cotton wool, dip in water and then damp some oxalic acid
powder on, rub the material and the rust vanishes right before your eyes
and now as a result I have my hearing 100% intact as the wife never shouted at me for "ruining" them contrived - 27-8-2007 at 10:38
hee hee .. nice bit of realism .. I'm looking for my oxalic as I typeC6H6 - 27-8-2007 at 14:14
I'm new to posting, but just if HCl Doesn't work, and the residue might be organic, you could always try an overnight basebath. (IPA, EtOH, or MeOH
saturated with KOH + a bit of H20). It's easy, and not very risky (the Ethoxide and Methoxide can be poisonous by absorbtion, so careful) I would use
90% rubbing alcohol and saturate it with KOH or NaOH and let the glassware soak.
[Edited on 27-8-2007 by C6H6]unionised - 30-9-2007 at 01:39
OK, so I'm digging up an old thread but I wondered if anyone else had come across these? Given the product's name, I wasn't going to us eit as a topic
title. http://www.cucinadirect.com/go/Product_5265.htmlAntwain - 30-9-2007 at 01:59
How the hell is that supposed to work? Abrasive?
Or snake oil? Eclectic - 30-9-2007 at 12:38
If there is a bit of diamond dust embedded in the copper surface, they will abrade away almost any surface. Finer than 8000 grit and you probably
wouldn't even see any scratching on glass.DJF90 - 5-1-2008 at 19:42
One cleaning solution I've heard of before is Caro's acid (sp?) IIRC it's a dichromate salt in dilute sulphuric acid. might be worth a shot...MagicJigPipe - 5-1-2008 at 20:19
I would like to add that dilute HF does wonders for rust and other oxides. In case you don't want to make it yourself (don't blame you) they sell a
~2% (I think) solution at Wal-Mart in a brown bottle (Wink-it brand I think). It's the one with all the horrible warnings of death and doom on the
front.YT2095 - 6-1-2008 at 04:33
Quote:
Originally posted by DJF90
One cleaning solution I've heard of before is Caro's acid (sp?) IIRC it's a dichromate salt in dilute sulphuric acid. might be worth a shot...
Caros acid is Sulphuric and H2O2 mixed, the one you mention is Chromic acid, often used on glassware to destroy organic matter.chloric1 - 6-1-2008 at 04:59
Quote:
Originally posted by YT2095
if it`s Just iron, then Oxalic acid works wonders
That's no joke. I had a porous porcelain morter without glaze and it had iron oxide stain for 8 years! I dissolved oxalic acid in boiling water and
poured this into the dish and walked away for 3 minutes and came back to morter white as new with a yellow solution. It was very hot and sunny where
I did this so any trioxalatoferrate(III) generated was reduced by the abundant UV rays to the yellow ferrous complex.leu - 6-1-2008 at 18:39
Aqua regia works very well for cleaning up such problems UnintentionalChaos - 9-1-2008 at 10:48
Sorry to deviate from the original topic but in response to chloric's post above: when I get my unglazed porcelain mortar stained badly and can't seem
to get it out with simple (inexpensive!) chemical means, I throw a scoop of white quartz sand in and just grind until it looks clean again. Works like
a charm.unionised - 12-1-2008 at 07:57
"How the hell is that supposed to work? Abrasive?
Or snake oil? "
Well Antwain, I haven't tried snake oil but these work just fine. They are based on a very old idea used by buttlers for cleaning decanters by
swilling a mixture of water lead shot and sand round in the bottle to scrub out the stuff.
Presumably this http://www.rohs.gov.uk/
took out the use of lead shot, but the copper works well enough.chemrox - 12-1-2008 at 16:29
Quote:
Originally posted by The_Davster
No experiance with that particuar reaction, but lots of experiance using pirhanna solution to clean stuff.
The proper method of using pirana is to add the conc. sulfuric first to the mess, and then slowly add cool 30-35% peroxide with stirring/swirling.
Could you give us the ratios? And once mixed is it re-useable like chromic solution?not_important - 12-1-2008 at 16:47
Generally you don't keep piranha around once used, especially if you've mixed the acid and peroxide to some ratio, then started the cleaning. If you
start with the H2SO4 and warm it up, then dribble in H2O2 giving it plenty of time to react and not build up an excess, you can let the used acid sit
for awhile, as often the reaction continues for a period of time, then slowly heat it up to 150 C or so, leaving it as mostly H2SO4 with any inorganic
salts formed in the cleaning. If the acid isn't strongly discoloured, you can store it for reuse. I would not store premixed piranha for any length
of time.stoichiometric_steve - 13-1-2008 at 10:19
Quote:
Originally posted by not_important
I would not store premixed piranha for any length of time.
i left some pretty dilute piranha in an emaille pot for about a week. when i came back, the pot had a tiny hole where the acid crept on the work
bench, ruining the plastic coated wood surface.Magpie - 20-8-2010 at 16:20
I can vouch for that. I recently bought an Allihn condenser off eBay with a bad rust deposit in the cooling jacket. As recomended on this forum I
filled the jacket with aqueous oxalic acid solution (5wt%), and within an hour the rust color had completely disappeared!
I normally woudn't buy glassware that looked that bad but it had the rare 40/50 taper fitting. Sedit - 20-8-2010 at 18:55
Hey maybe Im to much of a free thinker and all but..... Have you tryed to use common rust remover to get ride of it? Its sodium bisulfite and a couple
other things which I cant remember but its made for removing Fe contamination from stuff so it seems like its pretty much what your looking for. Try
the laundry isle.Magpie - 20-8-2010 at 19:26
Buy rust remover, buy oxalic acid. I already had the oxalic acid on hand. Where I live rust from tap water does not occur. So I'm done now.
