Sciencemadness Discussion Board - cleaning sulfuric acid

cleaning sulfuric acid

jimmyboy - 5-4-2005 at 14:02

is there an easy way to remove the carbon sludge from the acid besides distilling or centrifuge? any ideas?

thanks

runlabrun - 5-4-2005 at 16:27

what conc is the acid?
Carbon sludge? where did you get it from a car battery?
Hmmm if its a car battery i would have thought the crap was lead sulphate....

-rlr

HNO3 - 5-4-2005 at 18:03

I need to do more experiments, but in my production of Na2SO4 I noticed that when the acid was dilute, the colorant precipitated. Not very energy efficient, but you could try boiling, diluting, decanting, and then concentrating again.

cyclonite4 - 5-4-2005 at 18:31

I agree with rlr. I haven't actually opened a car battery, but I assume it would be PbO, PbO2, or PbSO4.

It can't be filtered out can it?

Blackout - 5-4-2005 at 19:02

cyclonite4, you can't filter out something from a conc. acid with regular filter paper, you need glass fiber ones.

[Edited on 6-4-2005 by Blackout]

sparkgap - 5-4-2005 at 21:57

Glass fiber, or if you don't mind long-term safety (like here, for instance) asbestos sheets.

Maybe he can decant if there's a substantial amount of the sludge.

sparky (^_^)

cyclonite4 - 5-4-2005 at 22:56

Quote:

Originally posted by Blackout
cyclonite4, you can't filter out something from a conc. acid with regular filter paper, you need glass fiber ones.

[Edited on 6-4-2005 by Blackout]

Maybe you should filter it out BEFORE you concentrate it?
And did I ever say use filter paper? No. I just said filter it.

runlabrun - 6-4-2005 at 00:57

car battery acid in itself is still to conc to use on filter papers, you could probably dilute it enough to do it tho.
I would think that the best way would be to decant the acid from the sediment sludge... does it form a sediment?

-rlr

ballzofsteel - 6-4-2005 at 01:18

CAn anybody tell me what might be put in
Hardware store Sulfuric acid to act as a corrosion inhibitor?

12AX7 - 6-4-2005 at 04:38

no personal derision.

[Edited on 17-4-2005 by Ramiel]

12AX7 - 6-4-2005 at 09:32

once more, no derisionary comments.

[Edited on 17-4-2005 by Ramiel]

jimmyboy - 6-4-2005 at 12:07

lead sulfate is white - not black - i am guessing the black is from organics that were left in the acid

Esplosivo - 6-4-2005 at 12:41

The black stuff is lead (IV) oxide, also known as lead dioxide. This is no guess

No really, that black powder was my raw material to start preparing some PbO2 for a potassium perchlorate electrolytic cell, until a really short time afterwards I learnt that it can can be produced by rxn between lead (II) and a hypochlorite. And well yes, some lead (II) sulfate is also present, since it is insoluble (especially in the presence of xs sulfate) but it's colour is white, as already stated.

Oleum - 6-4-2005 at 16:39

okay, I've boiled known battery acid and have never noticed much of any black lead compounds present...I think what some of us (or at least myself) are talking about is that nasty black concentrated sulfuric acid drain cleaner you get at the hardware store...does any body know how to seperate the black stuff out efficiently and easily? Using it is much cheaper than draining car batteries, at least for me...I couldnt imagine that it would be lead (IV) oxide...

runlabrun - 6-4-2005 at 17:21

Easiest way to get rid of the black crap?
find a different source....
There are many apart from the drain cleaner shit that is just watered down H2SO4... boil it down to get the goods... no problems.

-rlr

cyclonite4 - 6-4-2005 at 18:24

Quote:

Originally posted by 12AX7

Quote:

Originally posted by cyclonite4
arrogant?

Hmm, the English language doesn't have a synonym (homonym whatever) strong enough to describe it...

Tim

I'm aware of what you mean by arrogant. I was asking if you were calling me arrogant.

runlabrun is right. Batteries are a crap source. I can't find drain cleaner, but what I found was 'low fume' pool acid. It was a 34% w/v H2SO4 solution. Just boil it down, no filtering.

BromicAcid - 6-4-2005 at 18:26

Add some high strength H2O2 to your sulfuric and heat to 150C or so, should oxidize the carbon to CO2 and any dyes too. At least speculating from my arm chair it would seem so.

cyclonite4 - 6-4-2005 at 18:33

High strength H2O2?
Thats a waste!

Just find a better source of acid.

sparkgap - 6-4-2005 at 23:36

Hey guys, cool it. This ain't the place to be slinging at each other. :cool:

I must now ask: wouldn't adding concentrated peroxide cause some of Caro's acid to form? I shudder to even think about boiling it if so...

Why don't we have a "horrified" emoticon?

sparky (>_<

BromicAcid - 16-4-2005 at 12:35

Quote:

Add some high strength H2O2 to your sulfuric and heat to 150C or so, should oxidize the carbon to CO2 and any dyes too. At least speculating from my arm chair it would seem so.

Added 50 ml black drain cleaner to 15 ml 12% H2O2, the solution lightened slightly and vigourous fizzing ensued. Little droplets of hot H2O2 released hurt. The solution heated of its own accord and it was placed on a hot plate and put on a low heating setting with magnetic stirring. The mixture turned slighlyt yellow and was fairly clear, I took a picture with a beaker held next to it containing some acid before treatment. Being that the acid was clear and bubbles were still coming up like mad I added some more acid, it cleared up in a few minutes so I added some more, overall 15 ml 12% H2O2 treated a little over 125 ml concentrated acid. After a while the fizzing stopped and heating was discontinued. A fairly clean and simple procedure.

decolorized.jpg - 49kB

Man thats GREAT!

chloric1 - 16-4-2005 at 20:36

Bromic acid, Let em be the first to congratulate you on a novel yet simple discovery.

It is uncanny how our thoughts cross paths so often at relatively the same time. I went to the Patent Office website earlier this week looking for information on inhibitors for drain cleaning acid. I dug up the following patent that presents evidence to support your claim and expereimental results.US 5,429,764

The patent suggest a fairly wide variety of cationinc and nonionic surfactants. Some fluorinated. Would boiling until white fumes ensue further purify the acid? well, that certainly seems plausable if not quite correct. I was alreay going to get this stuff to dry chlorine gas but now I guess it can prove further useful. Many stores here don't carry it so I found a couple that do and well I was relieved. I am sure the trend is going to eliminate this product soon enough.

I hope this patent helps shed light on the mysterious nature of the balck acid dilema.

ADP - 14-6-2005 at 16:15

I tryed the same thing this afternoon. I started with a test tube of 10mL of acid. I then proceded to add 2mL of 25% H2O2. White bubbles and foam formed and then I stirred a bit. Finally I got a super clear product. I then tryed to heat the test tube. It boiled a small amount but I didn't want it to boil over so I stopped.

I noticed after a bit of heating however it started to turn back to a slight brown color.

12AX7 - 14-6-2005 at 17:03

Quote:

Originally posted by ADP
I noticed after a bit of heating however it started to turn back to a slight brown color.

Could be ferric iron. Iron, common as it is, wouldn't be too suprising.

Tim

BromicAcid - 14-6-2005 at 18:40

An additional note on decolorizing H2SO4, I have found so far that nearly any strong oxidizing agent works in my case. When I use my black drain cleaner acid in my apparatus to produce chlorine gas by dripping it from a separatory funnel onto Ca(OCl)2 the chlorine inevitably bubbles up through the acid when the stopcock is opened and as a result the acid becomes discolored ending up as off yellow from a starting color of dark brown/black. Also it should be noted that the acid I have contains any of a number of buffers and corrosion inhibitors, in all concentrations even after treatment with by boiling with H2O2 the acid refuses to attack steel wool appreciably even after 24 hours in it, this is at dilute concentrations or moderate concentrations so it is some messed up acid, I really need to distill it.

Which brings me to greenyppol’s thread that was closed earlier, as I stated in another thread I have distilled drain cleaner and I plan to do so again. However it is imperative to have good stirring and above most else there must be some heating element on the top of the boiling flask/still head to prevent water from condensing and falling back into the drain cleaner during the early stages, otherwise each drop hits and causes a violent reaction bouncing the flask and shooting liquid up and sometimes into the condenser. This is similar to the setup for the decomposition of ammonium nitrate to yield N2O, the upper part of the flask is heated to prevent water from dripping back into the reaction flask which gives higher concentrations of side products. Anyway, just some notes.

Also, ADP, I didn’t get any additional discoloration on heating which was what I did to ensure the decomposition of the H2O2 and to drive off some of the water, however as 12AX7 said Iron could be a possibility or maybe some organic matter from one source or another started to oxidize, something in the system unaffected by the H2O2 at the lower temperatures maybe. One other thing ADP, how much did your reagents heat on mixing?

Scratch- - 14-6-2005 at 18:59

Is the clearing of the acid a direct result of the H2O2 or from the formation of a 'pirana solution'? I forgot almost all the information about it and where I heard it. A search of the forums yielded nothing. Can somone elaborate on this?

Roebic

MadHatter - 14-6-2005 at 20:14

Bromic Acid, is that the Roebic Drain Flow brand of sulphuric acid you're describing ? Apparently,
the carbon is thrown in as some kind of warning indicator to a novice. Personally, I never
worried about that shit. Made good vacuum distilled nitric acid in any event. The carbon
was more of a pain-in-the-ass than anything else. Basic filtering through glass wool
was more than enough for my needs. This was until I discovered ROOTO through my local
Ace Hardware. I'll never go back to Roebic ! If you want good sulphuric acid OTC, that's
the way to go ! BTW, Misty is an excellent brand also but harder to get.

Pyridinium - 14-6-2005 at 21:21

BromicAcid, I have also noticed during recycling H2SO4 (contaminated with organic matter and metal ions), the conc. acid by itself will carbonize the organics and oxidize them after protracted heating at around 220-240 C. SO2 and water come off, as well as CO2 and H2SO4 fumes. It takes about a day of heating to make the acid turn from murky brown-black to pale straw-yellow.
I know it's a great deal of work and not really cost effective. Also dangerous.

side note... Oxidizers...

You and the other regulars on this forum obviously know not to put permanganates or chlorates in the acid to oxidize the contaminants, but some occasional readers might not. So we might as well tell them now: DON'T use permanganates or chlorates for this.

neutrino - 15-6-2005 at 02:26

Perchlorates also wouldn't be the best of ideas here.

In response to a previous question, the peroxide works by forming caro's acid (H2SO5

, which then oxidizes any organic matter present.

Organikum - 15-6-2005 at 04:25

A european brand of drain cleaner "STURA FACILE" says it is 66°Be H2SO4 what would be 94% to 98%. It has a reddish tint and foams when used as in in drying bottles or similar.

On heating to the boiling point it first turns black - after prolonged heating it turns almost perfectly clear.

My experieneces with battery acid 38% vary. Some stayed perfectly clear upon concentration and some got greenish - probably from iron salts present from storage in iron vessels.

/ORG

ADP - 15-6-2005 at 10:01

Hmm I wonder what H2SO5 + KNO3 would yield. Or if the H2SO5 would just decomp and make Nitric acid and a salt.

Scratch- - 15-6-2005 at 12:07

I was wondering something similar, I was wondering if H2SO5 could be stabilized by adding NaOH or other strong base?

H2SO5 + 2 NaOH => Na2SO5 + 2 H2O

BromicAcid - 15-6-2005 at 16:46

Persulfates are fairly stable salts, ammonium persulfate being somewhat widely avalible for etching circuits.

neutrino - 15-6-2005 at 17:31

I think SO52- is more accurately called peroxysulfate. Persulfate (the etching ion) is S2O82-.

Pyridinium - 15-6-2005 at 18:32

I'm pretty sure one of the preparations for Caro's acid (peroxymonosulfuric acid) involves reacting persulfate (peroxydisulfate) with H2SO4.

Might've been mentioned in another thread, sorry if it's redundant.

I think in the cold (-80 C) you can get it to form crystals. They are stable as long as the temp doesn't rise...

Purify sulfuric acid

Bonome - 25-2-2008 at 16:25

Is it possible to remove the impurities of Sulfuric Drain Opener? I don't found any topics about the question and I think it would be great if we can find a solution to purify Drain Opener acid because it's inexpensive and personally I'm in canada and I really don't know how to obtain pure sulfuric acid. My idea was to Distill at very high temperature to break the acid to H2O and SO3 but the difference in temperature between the cold condenser and vapour will certainly brake it so maybe you have more idea?

bereal511 - 25-2-2008 at 17:30

IIRC, there was a thread a while ago that discussed the use of hydrogen peroxide by slowly adding it to sulfuric acid drain cleaner and heating the solution gently, withsuccess in getting rid of most of the organics.

BromicAcid - 25-2-2008 at 18:18

Yes there are other topics on this around here though I am not sure about what they are titled. Distillation will work, giving you the azeotrope of something in the neighborhood of 96% sulfuric acid. The peroxide method that bereal mentioned above noteably lightens darker sulfuric acid though that doesn't say anything for any cations/anions that may be present, just some of the organics. Anyway, there are other threads.

If you haven't found out yet our search engine here is somewhat shoddy so I recomend going to google and searching with the modifier

site:sciencemadness.org

which will give results from this site. There are a few threads covering this from various aspects so good luck.

Bonome - 25-2-2008 at 18:54

Thanks, I found the topics.

titled 'cleaning sulfuric acid'

sorry for this double post maybe an administrator can delete mine?

chemrox - 25-2-2008 at 23:13

I made pirhana from drain cleaner and 30% H2O2. It cleared immediately on adding the peroxide. Ala Vogel 100% sulfuric is made by adding oleum (fuming acid) to the 98% which is obtained by distillation. I.e distill the drain cleaner and you've got reagent acid.

Pulverulescent - 7-3-2008 at 04:42

The first time I boiled battery acid, I got a brown acid, which became colourless on prolonged heating. As the colour vanished, small bubbles appeared and a small white precipitate formed.
The precipitate was silica and the colour was caused by dissolved carbon which was subsequently oxidised by hot H2S04.
Silicon carbide, it seems, had been added to the acid to prevent the formation of long lead crystals on the battery plates, which could short the cells.
If the drain-cleaner contaminant was organic it would be fully oxidised by strong heating.
Adding peroxide is a waste since hot H2S04 itself, is a good oxidiser.
I've thought of getting an old-type retort and distilling draincleaner but there's a chance the contaminent would come over with the acid and I don't know if borosilicate would withstand heating to 337*C. . .

MagicJigPipe - 7-3-2008 at 06:26

"and I don't know if borosilicate would withstand heating to 337*C. . . "

It most certainly will. I boil sulfuric acid all the time and have never had problems. Never. Except for the very first time I did it. I didn't realize how hot the H2SO4 was (even nearly 45min after boiling) and poured it in a HDPE container. It melted and sprung a leak while I was holding it so I panicked, dropped it and hot sulfuric acid went everywhere. "Fuckin flying shitballs!", I exclaimed as I deficated in my pants. Just kidding about the defication.

What's funny is at the time, my parents, knowing nothing about chemistry or chemicals said, "Your jeans look like you spilled a bunch of battery acid on them!"

Anyway, I think I may have read about this here somewhere but has anyone attempted distillation of H2SO4? In theory, this should yield extremely pure acid even from drain cleaner. As far as dissolved solids go it should be like reagent grade as someone mentioned earlier.

I always wanted to try it but I don't want my glassware to break. I'm theorizing about a decent way to heat the neck of the flask so that no water drips into the acid. Any ideas other than a topside mantle?

-jeffB - 7-3-2008 at 07:42

I'm working up my nerve to try distilling some drain cleaner. In the past, I've distilled lower-boiling liquids in an all-glass setup where I wrapped Teflon tape around the male connectors during assembly. It looks like the upper temperature limit for standard Teflon tape is somewhere around 300C. How bad an idea would it be to use standard "plumber's" Teflon tape in this temperature regime?

I'm thinking a water-cooled condenser is also a bad idea. I have a straight tube with 24/40 connectors on each end that's maybe 60cm long. If I use that as my first stage, then have a standard water-cooled West or Liebig after it, I'm thinking that I'd get low overall thermal stress and good containment of hot acid vapor. Or is the water-cooled stage overkill?

microcosmicus - 7-3-2008 at 08:01

Glass (of any kind) will withstand heating up to its softening point without any ill effect ---
above that temperature, it begins to sag and gets softer as you heat beyond that point,
ultimately leaving you with a puddle of glass where your flask was. For both borosilicate
and soda-lime glass, that temperature is around 500C, so 337C is within the
capabilities of glass.

What wrecks glass is not heat, but thermal shock. As long as you take care to apply the
heat gradually and evenly and let the glassware cool back to room temperature gradually
and evenly, it won't crack if it isn't scratched and free form internal stress.
For what you are doing --- boiling a liquid --- the liquid acts as a heat bath and keeps
the temperature steady as long as you don't distill to dryness, which is a bad practice anyways.
The advantage of borosilicate glass is that it has a lower coefficient of expansion, so can cope
with larger thermal shocks before it goes kaput. With care, you can certainly distill your
H2SO4 in glass vessels just as it has been done since the time of Gerber.

MagicJigPipe, I'm glad there were legs still left within those wrecked pants

I suppose that urination would at least serve to wash and neutralize
some of the spilt acid

[Edited on 7-3-2008 by microcosmicus]

Pulverulescent - 7-3-2008 at 14:04

Yeah, for one thing, I'd worry that my condenser would crack, even as an air condenser.
No way would I have water in it. . .H2S04 vapours should condense easily because of the high boiling point.
I don't want to endanger an RBF, either, or overheat teflon(teflon flu'?)!
And, using no lube might end with seized joints.
I'd certainly try it with a good retort, if I had one. Even then, though, the side-arm might get too hot to condense the distillate.
Oh, and before distilling I'd try to make sure the water was boiled off first.
MJP, when I was a kid I stuck carbon rods into a jar of battery acid, connected to the mains and switched on. . .a green arc formed even though there was a half inch gap, and the acid fountained up and onto the floor. It was a polished wooden bedroom floor and I thought, "shit it's going to turn to sawdust in a few months, and then I'll get a major bollicking. Nothing happened the floor but I had a few scares when the word floor came up in conversation.
Let's just hope someone else does the distillation and tells us(tongue in cheek)here.
P

Pulverulescent - 7-3-2008 at 14:50

Right now, I've got several litres of dirty acid. It's in a demijohn with rubber stopper. 'Thought rubber was ok, but it's disintegrating with time and now all this shit's sitting in the acid---in the middle of it.
I've just ordered a fritted funnel, though; should arrive any day.
If I want fresh acid, I'll electroplate copper from CuS04 sol..
An inert anode is soooooo useful---expensive but kinda essential, too.
P

Armistice19 - 17-5-2008 at 09:11

I actually had a quick question, I just obtained a couple car batteries from a junk yard, They seemed to still contain at least very small amounts of acid as the liquid fizzled when it came in contact with the concrete in my backyard. I filtered the acid through coffee strainers. As the lead sulfate collected in the mesh of the paper, a clearer liquid dripped into the glass container, and I obtained an atleast somewhat purified weak acid. I then bought a small propane camp-cooking stove from a sports outlet in order to boil the acid (this was much cheaper than buying a laboratory hotplate at the time). I put a teflon skillet filled with cooking oil onto the flame, and a pyrex cooking glass full of the acid into this. After a while the acid began to boil so I went over to a friends house while another friend checked on the acid for me. When I returned I found a yellow oily liquid at the bottom of the pyrex glass just as I had wanted, but to my surprise it was not fuming. In fact, it was fuming less than it was when I was just boiling off the excess water. I then proceeded to pour a drop or two onto concrete... no fizzle. Not being stupid enough to try it on my own flesh I skipped that part and funneled it into a storage bottle, and tried again. I achieved the same result the second time, an oily, yellow, non-fuming, and apparently unreactive liquid. This time when I funneled it into its bottle a drop of it splattered out and touched my leg....no burn, nothing, just a warm oily liquid is all it apeared to be. What did I do wrong? Perhaps I boiled it too long and destroyed the acid?

12AX7 - 17-5-2008 at 10:05

Try diluting it with H2O. If it heats up and acts like an acid, good bet it is what it should be.

Tim

ADP - 17-5-2008 at 10:46

I'm interested in attempting a vacuum distillation of sulfuric acid from drain cleaner. If I do this I'll take some pictures. Does anyone know where I can find a vapor pressure table for sulfuric acid?

MagicJigPipe - 17-5-2008 at 11:34

If it doesn't burn you instantly it is definitely not concentrated H2SO4. I got a pretty bad burn the other day from 35% sulfuric. Yes, it sat there for about 30 seconds but that's only 35%! Concentrated will char your skin instantly. Go to a hobby store (Hobby Lobby) and get some pH paper if you want to know for sure but I doubt you have any acid in there. How long did you boil it? It's possible that you boiled out all of the acid. Also, NEVER use "Pyrex" glass that you buy from Wal-Mart for chemistry purposes. It will go up to 320*C easily to boil sulfuric acid but once it cools down it WILL shatter. It IS NOT borosilicate.

Pulverulescent - 17-5-2008 at 14:05

Armistice 19, the cooking-oil may have contaminated the acid when its temperature reached a certain point.

The boiling temperature of H2S04, 339*C, might be high enough to cause the oil to boil and spatter into the acid.

If the glass was pyrex, you shouldn't have needed an oil-bath.

Careful monitoring and a fume-hood would have helped.

Slow heating, without the oil-bath would have given the result you wanted.

The residue you were left with may just have been the oil that spattered into the glass---the acid having been mostly driven off.

P

MagicJigPipe - 17-5-2008 at 14:14

In my experience a fume hood is not needed. Of course you should use some sort of ventilation, though. IMO, gentle heating isn't even needed either. Real borosilicate (Pyrex brand) beakers are so tough. I have used the same one for boiling H2SO4 for YEARS (easily 20 gallons of 33-35%) using everything from a wire "hotplate" (direct contact, like an electric stove that gets red) turned to full power to a propane flame. It is dirty but it just keeps on ticking.

IMO, there is no need to make it last all day. I just boil that shit on high and it seems to give the same results as taking it slow. For some reason the "fumes" have never bothered me. Not one bit. Maybe it's just because I'm semi-young, who knows... My lungs certainly aren't perfectly healthy, though.

Like Pulverescent stated above, NEVER use an oil bath for something that boils at over 300*C unless it is ABSOLUTELY necessary.

Pulverulescent - 17-5-2008 at 14:40

I'd still say pyrex cooking vessels should not be placed over a roaring flame.

Their sides and bottoms are very much thicker than those of ordinary RBFs and beakers.

Slow heating, at least in the initial stages, is always advisable, IMO.

P

Aqua_Fortis_100% - 17-5-2008 at 19:24

I have experimented cheap chinese iron enameled pan with some sucess.. I just make sure buying the stuff that have no flaws, cracks or other thing that expose the iron f the pan..

I have boiled battery acid in this with a iron enameled lid (with comes with the pan) loosely stoppered until fumes evolved .. Unfortunately I did not continued to raise the concentration since my backyard isn't that great and so the ventilation isn't too good.. But the amazing thing was that the enamel , like all the pan, did not seem to change with and after the procedure.. My sulfuric was slight yellow since I was using charcoal for heating and small flying ashes contaminated my H2SO4, even so I using the enameled iron lid..

IMHO seems to be much greater and probably safer than soda glass (yes.. many years ago I tried to do it in 1,25L coke glass bottle, glass beer bottles and even glass bolw and all these procedures were quite dangerous. Some bottles cracked and spilled hot sulfuric everywhere on the ground..God was good enough that anything occured to me..

) or maybe even pyrex

I have heard somewhere at this forum that conc. H2SO4 does not attack so well iron metal.. Does this make sense? If yes, then would be the enameled iron pan even a better choice..

But as soon as I discovered a chem supplier that sell tech grade 98% real cheap I discontinued concentrating sulfuric from battery acid, although I still like so much the idea of getting that stuff from auto stores (in old used batteries) FOR FREE.. Is actually my prefered source of dilute sulfuric, even with no well know concentration.. So I rarely dilute my conc. acid..

BTW, unfortunatelly this damn cool drain cleaner often discussed at this board is not OTC here.. So the only real way for all of those living in any part of the world is definately the battery electrolyte...

[Edited on 18-5-2008 by Aqua_Fortis_100%]

ADP - 17-5-2008 at 19:30

I did a vacuum distillation of HNO3 today, I am going to go buy a new propane tank and nozzle and attempt a H2SO4 distillation maybe next weekend. I'm going to use liquid lightning which should suffice. I'll let the water come over first and then distill at the hottest temperature to get the H2SO4 to come over. I'll post pics if I get the project underway... Any ideas?

MagicJigPipe - 18-5-2008 at 08:23

Quote:

I'd still say pyrex cooking vessels should not be placed over a roaring flame.

I didn't say anything about a (fake) Pyrex cooking vessel. However, they WILL work up to about 550*F in an oven even if they cool off at room temperature. Just apparently not with a direct source of heat.

Also, I still can't believe that the US seems to be the only country that has "pure" battery acid at it's auto-parts stores. I bought 5 gallons of 33.5% acid for less than $15 a few weeks ago. What about mechanics that refill batteries? How do they get it? I mean, that's what that 5 gallon "bag" was designed for. Mechanic use.

[Edited on 5-18-2008 by MagicJigPipe]

Pulverulescent - 18-5-2008 at 09:39

Quote:

Originally posted by MagicJigPipe

Quote:

I'd still say pyrex cooking vessels should not be placed over a roaring flame.

I didn't say anything about a (fake) Pyrex cooking vessel.

Do you see that (word) in my post, MJP?

The boron additive in glass doesn't eliminate the COTE; it merely reduces it, and heavy-walled vessels, if they're heated too rapidly, can crack from the induced thermal strain.

I once placed a hot pyrex cooking vessel on a wooden bench, only to have it shatter violently before my eyes.

I found that the sharp point of a nail which someone had driven into the bench from its underside had protruded a nano-metre above the surface of the wood, and it was this that caused the vessel to shatter.

The vessel was very hot and the nail not so. . .

If the vessel had been at, say 200*C it would still have happened---just not quite so, um, energetically.

Thin-walled RBFs are another matter, and don't need such precautions.

P

12AX7 - 18-5-2008 at 14:13

I regularly heat a moderately aged Pyrex bowl (must be at least 10-15 years old) over soft propane flame. Fine so far.

Tim

MagicJigPipe - 18-5-2008 at 16:40

I don't share your experiences with the fragility of borosilicate glassware. So far I have had no breakages due to thermal stress (or weak mechanical stress) and I used to abuse the hell out of my glassware because I used to think it was basically impervious to anything except for being broken with physical force. I still have all of my glassware from back then (except for the ones that were broken by the cops), too.

I understand that if it were heated fast enough it would break. But that's true with a lot of things. For me though, using normal lab techniques, they don't seem to break easily at all. Even when using a direct propane flame at full power. Maybe I'm just lucky?

Liquid Lightning

ADP - 18-5-2008 at 19:05

I don't know what the HELL consists of the "12 buffers" added to the "Virgin sulfuric acid" in liquid lightning but they sure know how to fuck it up. I attempted a vacuum distillation of the stuff today - I wanted to get the water out first and then distill over the H2SO4 to bypass the carbon etc. buffers they add in there.

Anyway at about 140dC the stuff started to boil, I'm not sure if the vacuum was on or not but anyway the whole solution started to foam up like soap detergent making it impossible to continue heating without the bubbles shooting up the condenser column.

This picture accurately describes my situation...

It worked fine for nitric acid synthesis/distillation... perhaps the nitric oxidized the carbon etc. buffers... I'm curious if I added a small amount of conc. H2O2 to clear up the buffers and then distilled what would happen. Maybe I'll try that this week. Any suggestions?

MagicJigPipe - 18-5-2008 at 19:55

DO NOT use Liquid Lightning. It is quite possible that it's the worst acid for this purpose. The "virgin" and "12 buffers" comment should have clued you in. If it foams, well, don't buy it again! I assume you got it from Home Depot because that's the only place I've seen it. Another thing that told me to steer clear of it is that it didn't have a plastic bag wrapped around it.

Even if you don't have an Ace Hardware in your area, just about any other brand of H2SO4 drain cleaner will work better. That is the blackest drain cleaner I have EVER seen! Yuk!

Also, you shouldn't use cold water to distill H2SO4. There's a post that Sauron made around here somewhere that explains why and also what temperature your coolant water should be for certain distillate temperatures. I think the general rule was to keep it around 20 degrees below the boiling point of the pot liquid.

Also, where did you buy your West condenser and what brand is it? I have one that looks the exact same (except I broke mine

). (I know they all look basically the same but this one is EXACTLY the same).

Before I stop, here's an anectdote about how sellers on eBay lie their asses off just to make money. One was selling a 200mm Ailhin condenser that was stained so redish (hard water, I assume) you could barely see through it. They claimed that it had "hardly been used" and was "like new". They also had a reserve on it and had started the bidding at $40!! It angered me greatly...

Formatik - 19-5-2008 at 01:33

How about adding anti-foaming agents?

Pulverulescent - 19-5-2008 at 02:54

Quote:

Originally posted by MagicJigPipe
One was selling a 200mm Ailhin condenser that was stained so redish (hard water, I assume) you could barely see through it.

I saw a red-cored condenser recently, too---eBay or UGT; it was very red---scarlet/crimson, and I assumed the glassblower was into red glass and had inserted it into the condenser purely for effect.

I thought it looked really good---so good---I wanted it kinda' badly.

The one you saw may have just had rust in it; my sole condenser has so much rust (reddish-brown) I was afraid it'd interfere with heat transference during distillation.

P

ADP - 19-5-2008 at 03:56

Quote:

Originally posted by MagicJigPipe
Another thing that told me to steer clear of it is that it didn't have a plastic bag wrapped around it.

Also, where did you buy your West condenser and what brand is it? I have one that looks the exact same (except I broke mine

). (I know they all look basically the same but this one is EXACTLY the same).

They started putting plastic bags on them but yes Liquid Lightning is pretty bad stuff. The only problem is that it's the only thing I can really get around here that I KNOW of... I'd love to get a hold of some rooto but that might require a little trip to the next town over. I'll keep it in mind though.

As for my West condenser, it's Ace glass and I actually got it for free. My high school was cleaning out the lab when I went there and it was covered in dust on a top shelf somewhere so I asked to have it... I DO need to run some H2SO4 through the outer case to remove the hard water stain but just haven't yet as it doesn't really affect anything.

Anyway as far as liquid lightning is concerned I think that it is fine for synthesis of say HNO3 and then distilling but I'm going to have to find a better brand if I want to use it alone as H2SO4.

MagicJigPipe - 19-5-2008 at 04:12

Yeah, mine is Ace, as well. That's why I almost cried when I broke it (not really, but, you know). Are you in the US? Try looking your some smaller "Mom and Pop" stores. That's the only place it is available here except for Ace Hardware (and there's only Ace Hardware, all of the other ones have closed down since the late 90s apparently).

ADP - 19-5-2008 at 04:20

Yeah I had a graham condenser that broke once and made me feel the same way. Yeah I'm located in MS in the U.S. There's an Ace hardware in the town over from me that I might visit today if I get time - if I do I might buy a few liters of rooto for the summer. Basically I have all summer to experiment and what not so I'm making the most of it.

ADP - 19-5-2008 at 16:42

I couldn't find rooto at ace but purchased "liquid fire" instead which I know to be good sulfuric. The store was pretty small though so I'm going to go to a bigger one in a week or two. More experiments to come hopefully.

mr.pyro - 24-5-2008 at 21:57

Liquid Fire is good stuff. That should work well for you. It has always worked well for me for nitrations and distilations.

grndpndr - 26-5-2008 at 11:54

Never had any problem with the Santeen brand SA drain cleaner from ace either though its the usual waste sulfuric acid drk brown black.I had assumed it had been used to pickle steel during the manufacturing process and the majority of contaminants were iron oxide.Never the less 0 problems thus far with nitrations.Although despite the cost I prefer buying virgin electrolyte from the local garage and reducing it per hotplate.I am fortuate though in that we have a chemical supply that sells SA and 70%nitric and will deliver free of charge if your on thier truck route.makes for cheap 70% Nitric w/o shippin /hazmat.

Total delivered 2.5l carboy some $36!

Can someone share a Mail order/ chain garden center AN source?CAN calcium AN 27-0-0 is satisfactory.

[Edited on 26-5-2008 by grndpndr]

[Edited on 26-5-2008 by grndpndr]

RFC : distillation of sulfuric acid

Chemist514 - 21-8-2008 at 09:25

Hello all!

Just a request for comments regarding my latest attempt at this process..

After some thought we have decided to leave the drain opener acid sources in the original packages, we have not been able to locate a reputable chemical source for pure sulfuric acid, even requests for battery acid from the usual places results in suspicion, seems this one is not a locally available item.. we will purify only the acid from "various sources"... spent fisher bottles from the local university, discarded batteries etc, and leave the rest for future considerations (pure is not needed to make some other acids etc..)

20 ml or so was placed in a 100ml 14/20 flask connected to a basic distillation setup (no water) and allowed to reach some 350 degrees. the flask was allowed to dry on cooling, after the water had passed over and we waited for the acid to fume it was noticed that the acid was not condensing back, it was leaving as vapor through the vent port on the receiver adapter..

Question : How long must this condenser be? I can chain 2 lieburg and then feed that into a graham but this seems like overkill, what is being used commonly for this app? Looked like basic 14 inch west's in the pics..

This process was again done with a 250 ml flask and much less heat, 270 approx, seems like we have about half volume removed as water, need to test ph.. acid! not strong but that was not expected!!

I really would like some pure, and we have it in 4-5 small bottles that need to be mixed for proper storage.
I wonder whats left in there after bromicacid's H2O2 cleanup?

Additional info.. I added about 10 ml of Clear-line drain opener which is available here.. at about 250 C the pink was gone... well, its not gone, just.. its not pink now.

Update : The 250ml flask is room temp now, and clear as water.. nice that, we know theres scat in there but its alot better to look at!

Scanning over the various threads we find we should not be using a jacketed condenser, I have no tubing with a ground glass joint for this app so I'll chain at least 2 of them or pick one and add the graham..

Sand needed to be roasted? and sifted for smallest grain size...

Erm, well its roasted now! lol. I just sifted it, but we didnt have heat transfer problems so this is just proper procedure I suppose..

And we will leave the hotplate settings fixed one level per hour.. must go slow to see where this window or water end and acid boiling starts..

Kudo's to UGT all 14/20 glassware purchased there and must be at least decent as it survived this... lol.

Wish I had some input but the musing helps muchly. thanks for your time.

New (Last?) Try :

Ok, lets use what we've learned so far...

I believe it was Woelen who saw a reference to using a vigreux as a high temp distillation device.. This is a nice idea!

Placed 200-250 ml of waste acid in a 500 ml flask and added an adapter, stopper in adaper, 14/20 to 24/40 adapter, vigreux metal keck to 24/40 down to 14/20 then a 14/20 "drip tip", maybe 6 inches that, will allow me to switch flasks better...
Used fine sand well dried in the sand bath and wrapped the first adapters in fiber insulation to stop water from dripping back.
Applied heat... I'm suffering from hold up with 14/20 here. need to keep setup microscale though.. maybe a 24/40 adapter should be obtained...
*sigh*
54 mins running and temp at 234 C I see vapor build up in the "condenser"...

[Edited on 21-8-2008 by Chemist514]

[Edited on 22-8-2008 by Chemist514]

Chemist514 - 22-8-2008 at 10:14

Hmmnn... Cant seem to edit, odd.

now 2 hours 11 mins, temp 290 C less water now in hot end of the vigreux.

Must locate info on if system must be cooled and dried before passing over the sulfuric acid itself, temps should be way off, may be hazardous!
The Vigreux is much thinker glass... its not touchable now which is starting to concern me slightly..

This took some 9 hours!
Ok.. next day, all went well with the first batch!!! *DANCE!*

Second batch had some more questionable acid in it, some very strange green-yellow, oily liquid came over before even the water, I think it may be whatever substance would form in boiling H2SO4 a partially dissolved stirring bar, a lot of lead sulfate, plus whatever else is in there that I do not know about... I'll assume silence..
Temp being held for 2 hours at 290 - 300 , that should burn out whatever may be in there, then I'll start over with that batch in clean glass.
*ponder* alot of brown fumes were evolving, perhaps some nitrate was in there.. I think Sulfuric acid vapor is white from what Ive read here..
What color is teflon smoke? lol.

All the best to everyone, be safe!

[Edited on 23-8-2008 by Chemist514]

darel - 28-8-2008 at 23:13

I use a 200mm graham condenser with a drip tip. My setup is simple and get at least 98% concentrate. I put all 32oz of Rooto brand in a 2 liter flask and have an upside down U joint that connects to the condenser so it's parallel with the flask. The flask and elbow are covered in tin foil. The setup is 24/40. The fisrt 100ml or so is water, then a dense milky white smoke shoots back and forth through the elbow and condenser. The smoke doesn't condense but disipates into the air when it make it out. Sometimes a cloud of smoke stays in the apparatus during the run. I collect everything after that plume of smoke in a seperate container because from there on out is damn clean H2SO4. There is a crystalin substance at the bottom of the flask and when 50 ml remains in the flask I shut off the hot platead let everything sit and cool until I can touch it.

I have never tried a reflux setup. How tall is vigruex?

darel - 6-10-2008 at 18:09

I had great success this weekend with a product from lowes. It's called Greased Lightning Power. Less than $7 after tax. I didn't take measurements to figure for the amount of water, but I would say in the neighborhood of 60-70% sulfuric acid. Setup was simple. 2 liter flask with a graham condenser. All 24/40 joints and tin foil around the flask and first half of the elbow.

Boiled off the water first at low on the hot plate. Foam was coming off pretty good, but settled down after a few minutes. You know the water is gone when there is no more bubbles and you have a hot, still brown liquid.

Once all the water was gone, I cranked up the heat to medium. You know you have acid when the last few drops of water came over and the collection beacker warms meaning acid is present in the solution. I switched beackers and started collecting a thick, dense, slightly yellow liquid.

I actually boiled this stuff dry till the black residue was left and the bottom was pretty much dry. I took my hydrometer and the liquid weighed out 1.839

.

I have always used Rooto but I haven't been able to find it lately. The biggest differences with these drain cleaners was with Rooto, during the distillation a thick milky white cloud would come off and the contents in the flask would clear. This stuff from lowes had a little white cloud at the beggining of the acid coming over (another way of telling the water has boiled off) and the contents of the flask was the same color throughout the distillation.

Both of these drain cleaners had the same shinny, glassy crystals leftover. Not sure what it is.

Overall great product. Just thought I'd share.

EDIT BY POLVERONE: 800 pixel width maximum for attached images!

[Edited on 10-6-2008 by Polverone]

cleaning sulfuric acid

darel - 7-7-2009 at 21:40

Anyone know what the crystal like solid on the bottom of the flask is after distilling Rooto?

1281371269 - 8-7-2009 at 05:43

Some high boiling point impurity in the acid I would assume... Do you have any information on what was in the drain cleaner?

hissingnoise - 8-7-2009 at 05:57

It would have to be pretty inert to survive boiling H2SO4---could be SiO2, but why it's there is anyone's guess. . .

watson.fawkes - 8-7-2009 at 10:40

Quote: Originally posted by hissingnoise

It would have to be pretty inert to survive boiling H2SO4---could be SiO2, but why it's there is anyone's guess. . .

I can guess, but only guess, that if it's SiO2 it's there as a nucleation agent for evolved gas. The combination of bumping and enclosed pipes is not a good thing.

Luftwaffe - 24-8-2011 at 01:06

I am curious as to what impurity that is and if non-distilled H2SO4 would be unsafe to use in chemical synthesis's specifically nitrations.

I have recently been thinking of purifying sulfuric acid using a very indirect but possibly successful route which would include vacuum distilling HNO3 from the raw drain cleaner sulfuric acid and a recrystallized nitrate salt found in fertilizers (which in my case is KNO3). I would then use the nitric acid to oxidize SO2 by creating a sulfur dioxide gas generator and bubbling it through the nitric acid which would produce in theory pure diluted sulfuric acid which you could then boil to concentrate. This process assumes that no impurities boiled over in the nitric acid distillation for it to work and from what everyone is saying it seems to have a low volatility which leads me to believe it would not boil over.

Minus the liberation of NO2 when oxidizing SO2, it seems like it would be safer than distilling the raw H2SO4 at high temperatures, even if you were to vacuum distill it. Perhaps I am blowing things way out of proportions and over-complicating the whole purification process. I just want to make impurity free sulfuric acid in a safe manner and whether that be distilling and separating those mystery crystals or doing the whole procedure I lay'd out, I don't know, which I guess is why I'm here!

This is my first post here on Sciencemadness, hopefully I didn't break any rules!

windchime - 28-12-2011 at 12:46

Interesting that the liquid lightning brand drain cleaner up here in Canada is 94% vs. 44% by weight in the states. There is no mention of inhibitors on the Canadian bottle label either.
http://liquidlightning.net/template.php?go=msds
I purchased a bottle the other day. The contents have a bit of a dark brown colour to them, not sure if that's a result of age (oxide buildup) or contaminants/additives. I'm going to try the heating method first to see if i can clear it up.

Amusing the regional differences in product content. I'd make a joke about canucks being more responsible... but I'll save the bad karma for after working with the acid.

freedompyro - 14-2-2012 at 20:14

After further testing I have confirmed that the cleaning of H2SO4 by the addition of 5% H2O2(30%) works somehow...

I first brought a mostly clear solution of Rooto to a full boil which took me about 30 minutes with a propane burner. It turned to pure black with a hint of red when a bright light was shined through it.

It was cooled back to room temperature and maintained it's black color. I poured into another flask. To the original flask I added H2O2(30%) in an amount equal to 5% of the weight of the H2SO4. The H2SO4 was poured slowly back into the original flask and some light boiling occurred in a few spots.

After being heated for 5 minutes the solution had turned clear with a slight hint of yellow and lots of light bubbling. After being brought to a full H2SO4 boil emitting clouds of white fumes after 20 more minutes and being lowered to a simmer for 5... It still maintained the clear color with a slight hint of yellow. No change on cooling... When fully cold it actually appears 100% clear on first glance with 900ml in a 1000ml flask, but if you look at with an angle in a tall clear bottle you can see a very slight yellow tint.

One question I need to ask is... What is the concentration of H2SO4 brought to a full boil for a couple minutes? Is it 98% or is it around 96% or so?

Note: The top half of the flask was insulated with aluminum foil both times. The H2SO4 seemed to radiate so many BTU's that it could not be brought to or held at a boil without the flask being insulated and the heat held against it's lower sides with the use of aluminum foil sheets surrounding the burner.

[Edited on 15-2-2012 by freedompyro]

Neil - 15-2-2012 at 11:25

Quote: Originally posted by freedompyro

After further testing I have confirmed that the cleaning of H2SO4 by the addition of 5% H2O2(30%) works somehow...

I first brought a mostly clear solution of Rooto to a full boil which took me about 30 minutes with a propane burner. It turned to pure black with a hint of red when a bright light was shined through it.

It was cooled back to room temperature and maintained it's black color. I poured into another flask. To the original flask I added H2O2(30%) in an amount equal to 5% of the weight of the H2SO4. The H2SO4 was poured slowly back into the original flask and some light boiling occurred in a few spots.

After being heated for 5 minutes the solution had turned clear with a slight hint of yellow and lots of light bubbling. After being brought to a full H2SO4 boil emitting clouds of white fumes after 20 more minutes and being lowered to a simmer for 5... It still maintained the clear color with a slight hint of yellow. No change on cooling... When fully cold it actually appears 100% clear on first glance with 900ml in a 1000ml flask, but if you look at with an angle in a tall clear bottle you can see a very slight yellow tint.

One question I need to ask is... What is the concentration of H2SO4 brought to a full boil for a couple minutes? Is it 98% or is it around 96% or so?

Note: The top half of the flask was insulated with aluminum foil both times. The H2SO4 seemed to radiate so many BTU's that it could not be brought to or held at a boil without the flask being insulated and the heat held against it's lower sides with the use of aluminum foil sheets surrounding the burner.

[Edited on 15-2-2012 by freedompyro]

Sounds like you had organics which were consumed by your impromptu piranha solution. Take the density to determine the concentration.

AJKOER - 26-2-2012 at 14:03

Here is a somewhat more complex and expensive route, but no distillation of H2SO4 and perhaps interesting to some.

1. For the given amount of H2SO4, calculate how to divide it to produce equimolar amounts of hydrated ferrous sulfate and ammonium sulfate, and also have some residual H2SO4 as well.

2. Prepare the hydrated Ferrous sulfate by dissolving Fe in H2SO4, and separately, bubble pure NH3 into H2SO4 to form Ammonium sulfate. For Ferrous sulfate, follow preparation at:

http://www.crscientific.com/ferroussulfate.html

For Ammonium sulfate, per Wikipedia:

2 NH3 + H2SO4 → (NH4)2SO4

"A mixture of ammonia gas and water vapor is introduced into a reactor that contains a saturated solution of ammonium sulfate and about 2 to 4% of free sulfuric acid at 60 °C. Concentrated sulfuric acid is added to keep the solution acidic, and to retain its level of free acid. The heat of reaction keeps reactor temperature at 60 °C."

3. Mix the equimolar amounts of hydrated ferrous sulfate and ammonium sulfate with the residual H2SO4 to make Ferrous ammonium sulfate. See procedure at: http://motion.kodak.com/motion/uploadedFiles/US_plugins_acro...

4. Dilute and crystallize out the Ferrous ammonium sulfate to form light green crystals.

5. Combine green crystals, distill water and Oxalic acid dihydrate (costs about $2.64 a mole), and heat forming a yellow precipitate of Iron Oxalate, and also some Ammonium oxalate. Separate out the Iron salt and cool to collect the Ammonium oxalate crystals. Boil the solution to remove any remaining Oxalic acid and/or Ammonium oxalate. Reactions:

(NH4)2[Fe(H2O)2(SO4)2]*4H2O + H2C2O4*2H2O --> FeC2O4 (s) + H2SO4 + (NH4)2SO4 +8H2O

(NH4)2SO4 + H2C2O4*2H2O --> (NH4)2C2O4 + H2SO4 + 2H2O

H2C2O4 + H2SO4 --Boil--> H2SO4 + H2O + CO2 + CO

The remaining solution is H2SO4 purified essentially by crystallization and some boiling. Side products are Iron oxalate and Ammonim oxalate.

[Edited on 27-2-2012 by AJKOER]

chucknorris - 10-12-2012 at 07:34

Oh well.. Sulfuric acid boiling temp at 5 pascals(which is the max vac my pump will make) seems to be 62C. Can it be distilled in order to purify it or does it decompose?