Mabus
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Crystal clear H2SO4 drain cleaner
So I recently found out that a local home improvement retailer sells this product:
http://www.cormen.cz/p/921/5663/cleamen-420-odpady-sanitarni
The label indicates, and I quote: "Contains: >30% sulfuric acid, <5% water. Composition: sulfuric acid 98%" I have no idea why the manufacturers
write the components that way (not the first time I've seen it written that way on a product), but since all drain cleaners I know use >90% H2SO4 I
figured the latter value was the real one. When I picked up the bottle, it felt too heavy to be just 30%, so I decided to buy one to investigate. When
I open the bottle I notice it has a seal with a small opening and when I poured the content in a beaker, the liquid that came out was transparent,
without the typical red or black dye/inhibitors. I tried to determine its density and I got values between 1.82-1.85 (I have crap scale, so I also got
values higher than the density for 98% H2SO4), which means its conc. is above 90%, so it could be ~98%. Since I thought it's too good to be true, I
decided to check for any dissolved salts/inhibitors. I neutralized a small amount of drain acid in a test tube with some ammonium bicarbonate and kept
adding until it stopped fizzling. I then began heating the ammonium sulfate solution with a blowtorch to sublime it and see it there's any residue.
Once the water boiled off, the salt began decomposing and sublimed, kept depositing on the upper part of the tube so I heated all the tube to get rid
of it. The only thing that remained in the tube was a small amount of a high boiling liquid (I assumed to be a tiny amount of sulfuric acid that
reformed from the ammonium sulfate decomposition and condensed back in the tube). Further heating completely eliminated all the liquid and no salt or
any other residue were left inside the tube. The ammonium sulfate did not turn black during decomposition, so I assume no organic compounds were in
the drain cleaner (my baking ammonia is very pure).
Now I feel bad that I've wasted time and money on cleaning dirty drain cleaner acid when I had better options.
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Melgar
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Good to hear! All the cheap acid-based drain cleaners around me are black to start with, but about 10-20mL of 30% H2O2 will clean a liter up in a
week or two, to a very pale yellowish-brown color. The only problem is that it takes about a month for the oxidizing properties conferred by the
peroxide to completely go away, so you don't want to use that stuff beforehand without removing a small amount and adding something like oxalic acid
until the reaction slows. I'm pretty sure the black is just finely-divided carbon, meaning the drain cleaner is probably waste from some benign
industrial process meant to remove organic residue.
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Mabus
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For the dirty acid I used NileRed's tip of simply boiling it without peroxide, as I can only find 3% peroxide and if I'd use that I'd dilute the acid
too much. I only added peroxide afterwards, to remove any leftover impurities.
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Melgar
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Incidentally, I just realized a few days ago that once the color is gone, you can boil the acid, which decomposes any remaining peroxide, I feel kind
of silly not thinking of this sooner.
Mabus: cream peroxide for bleaching hair actually works okay, although I think the highest they sell that in is 12%. The emulsifiers take a while to
break down though, unless you boil it. What might work better actually, is boiling it, and then slowly and carefully adding a
mixture of acid and 3% peroxide once you've gotten as much of the color out as you can. Then boil that, which should drive out most of the water and
also break down anything that might be left.
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woelen
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Quote: Originally posted by Mabus  | | [..]Now I feel bad that I've wasted time and money on cleaning dirty drain cleaner acid when I had better options. |
The glass can be half empty, but it also can be half full 
Look at it from the bright side: Now you have an OTC source of very clean and pure sulphuric acid which you can use from now on. If I were you, I
would buy a bunch of those bottles and put them aside. They may be gone tomorrow!
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Sulaiman
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Good advice. The hardware shop that I used to buy drain unblocker sulphuric acid from, suddenly had no shelf space for it.
On bleaching ...
I recently put anhydrous calcium nitrate in drain unblocker H2SO4 and let it 'soak', with a daily aggitation.
By the first day the liquid was colourless and the sediment white.
No heat applied.
http://www.sciencemadness.org/talk/viewthread.php?tid=70712#...
[Edited on 7-11-2016 by Sulaiman]
CAUTION : Hobby Chemist, not Professional or even Amateur
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Mabus
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@Melgar that sounds interesting
@woelen I'm already planning that. Which reminds me... Some years ago I found fuming HCl (>30%) at a local hardware store being sold in small
bottles and had the brilliant idea of buying about 2 l of the stuff. A bit contaminated with iron, yellowish and was sold in some pretty terrible
plastic bottles, which I changed to more sturdier glass ones. But it was a good idea, because they stopped selling that fuming HCl shortly after I
bought the last bottle (probably they just cleared some stock) and right now all the HCl that I can find is is <20%. Used quite a lot so far, but I
still have enough for my needs.
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