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Author: Subject: Gitting rid of Cl2
SsgtHAZMAT
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smile.gif posted on 8-3-2007 at 21:29
Gitting rid of Cl2


I have a lot of Cl2 in industrial cylinders that I have to get rid of. I am letting it escape by running it through a hose, into a barrel of water and percolate up into the atmosphere.

After a few hours the water turned so green it was dark blue to black.

Question, how long should I wait before I start getting rid of the water?
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Sauron
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[*] posted on 8-3-2007 at 22:02


I don't know what you have there, you probably made chlorine water Cl2.6H20 and that probably reacted with the container walls and made whatever your blue-black mung is.

If I were you, I'd run the Cl2 into a cold (iced) soln of NaOH and thereby make NaOCl soln (bleach). If you don't keep it cold you will make sodium chlorate instead.
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[*] posted on 8-3-2007 at 22:48


Why are you wasting precious chlorine??
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Sauron
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[*] posted on 8-3-2007 at 22:58


My guess it that the tanks are no longer safe and can' be shipped. I don't know why he can't transfer the Cl2 into new cylinders (with a refilling station) but releasing the Cl2 to the atmosphere is not only a bad idea, it is probably highly illegal.

However so called HAZMAT disposal outfits do shady shit like this all the time...
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[*] posted on 9-3-2007 at 03:42


Where in the world are you located at?

If within a days drive I'll gladly come get some and take it off your hands!

Anyhoos, you should do as Sauron says and add sodium hydroxide, or lye, to the water which will form the hypochlorite, aka bleach.

Actually if you added it to HOT water, you would form the chlorate which ain't in itself a bad molecule... sodium chlorate makes a good weed killer and you can sell it on the internet, pehaps to some of those pyro follks.
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[*] posted on 9-3-2007 at 03:52


Hey, is that you Sarge? Still in the desert? Did you not ask a while back on <a href="http://sciencemadness.org/talk/viewthread.php?tid=3780">how to dispose of hypochlorite</a>?

Yeah, turn the chlorine into hypochlorite with lye, then have a go about it with oxalic acid, I guess. ;)

sparky (~_~)




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[*] posted on 9-3-2007 at 04:56


geez........ they hiring hazmat guys nowadays that don't know basic chemistry?


pls bubble it into naoh as all seeing one eye guy says

but the best would be CaOH since that'll solidify instead of eventually releasing the Cl gas again when the NaOCl decomposes

[Edited on 9-3-2007 by Maya]




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[*] posted on 9-3-2007 at 05:03


SET is a good environmental company for cylinder disposal.

http://www.setenv.com/

I posed a similar question for how to dispose of chlorine in this thread:

http://www.sciencemadness.org/talk/viewthread.php?tid=1264




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Maya
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[*] posted on 9-3-2007 at 05:07


I'm guessing he's in Iraq somewhere needing to get rid of a lot of WMD precursurs :o



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[*] posted on 9-3-2007 at 05:24


Sodium Thiosulfate is another way to destroy it, perhaps another hazmat station has an excess of this they don`t want?



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[*] posted on 9-3-2007 at 06:30


Do you know anyone who owns a swimming pool? That would be a good way to dispose of your chlorine - use it to chlorinate the pool water.



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[*] posted on 9-3-2007 at 07:37


or go to the local water sanitation department, they would love to use the Cl to clorinate, sanitize their water supply



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[*] posted on 9-3-2007 at 11:09


@Maya, excellent suggestion to use Ca(OH)2 to get the Cl2 into solid form as bleaching powder. However, if this fellow IS in the sandbox (middle east, slang used by expats who work there and hate it) then that would make great sense since bleaching powder = military DC decontamination agent, which is standard stuff for decontaminating mustard, many OP agents etc.

However, doing anything as logical as this would go so completely against the illogic of the military that the shockwaves of sanity would cause chaos all the way back to the five sided cookie factory in Arlington. Grown men would swoon. Women would belch. Dogs and cats would lie down together, Arabs and Jews would kiss and make up. Defense contractors would go begging, their kids would go shoeless, their wives would have to sell pencils on the street around Dupont Circle. In short, it would be the end of civilisation as we know it.
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[*] posted on 9-3-2007 at 13:40


Any Cl2 salvagable could simply be diverted to water treatment .

Cyanuric acid , pool chlorine stabilizer could possibly
soak up the chlorine , forming TCCA ....or perhaps
a sodium dichloro derivative is another way of salvaging the chlorine in a safely storable form , which can be used
as disinfectants , or for water treatment .

For the rest :

Convert the Cl2 to hypochlorite and then use urea in the
reaction scheme which is optimized for hypochlorite
decomposition under conditions where hydrazine is
not the intended result .

There are patented decontamination processes describing this method ....
and I know I mentioned this in the hydrazine thread
when trying to explain about the narrow window of
reaction conditions required for producing hydrazine ....
and how even a slight variation away from that window
would simply decompose the reactants with no hydrazine
produced .

[Edited on 9-3-2007 by Rosco Bodine]
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[*] posted on 11-3-2007 at 03:12


Quote:
Originally posted by sparkgap
Hey, is that you Sarge? Still in the desert? Did you not ask a while back on <a href="http://sciencemadness.org/talk/viewthread.php?tid=3780">how to dispose of hypochlorite</a>?

Yeah, turn the chlorine into hypochlorite with lye, then have a go about it with oxalic acid, I guess. ;)

sparky (~_~)


Bingo

Yes it was I that was getting rid of the other cl back a couple of years ago.

And all good answers, and I do know a lot of chemistry, but the problem is that I cant move it and have almost none of the other items that have been listed as ways to help out. Hell, it is stunning that I have the web as much as I do off the satellite!

So I am pretty limited in what I have that I could mix it with. Also to mix it I would be running my torch tubes into a 55gal barrel with limited.
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[*] posted on 11-3-2007 at 03:19


Quote:
Originally posted by Sauron
I don't know what you have there, you probably made chlorine water Cl2.6H20 and that probably reacted with the container walls and made whatever your blue-black mung is.

If I were you, I'd run the Cl2 into a cold (iced) soln of NaOH and thereby make NaOCl soln (bleach). If you don't keep it cold you will make sodium chlorate instead.



Ok I may have some NaOH but I dotn think I have enough. Also Ice is in low supply, but this method may be useful.

Thanks! I have to go check.
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[*] posted on 11-3-2007 at 06:03


Sarge, are you (ahem) in a non CONUS location?

No need to be specific.

Can you tell us how many cubic feet or meters of Cl2 you have to dispose of? If so we can tell you how much calcium hydroxide or NaOH and water would be needed. If water is scarce then we will have to think of other options.

Can you dig a pit and wrap the cylinders in primacord and cut them open (remotely) underground? You'd need earth movers and manpower and EOD guys or engineers.

Can you get some airlift, tape TH3 grenades to each clinder and drop them on Iran? (Just kidding.)

I had assumed you were somewhere out passed Barstow and dealing with a few old cylinders, but if this is more serious than that then we must be creative.

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[*] posted on 11-3-2007 at 06:24


Lets say I am in the desert. (I wish I was in Ca!!!)

I have roughly about 9 tanks. There is no way to know how much is in the tanks as they do not have marking that anyone would trust, and we do not have a reliable pressure gage. Lets just say they are the same sized as a shop O2 tank for a torch cutting kit. Like what you would find in your local auto fix-it shop.
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[*] posted on 11-3-2007 at 06:40


All right, 9 standard cylinders so if we assume, arguendo, that they are all full to normal pressure for a Cl2 tank then we can get a reliable maximum quantity of Cl2, in Kg therefore moles and start writing some stoichiometry from there. You may have less in fact but not more. Nine cylinders is manageable. Could be worse. Could be ISO tankers, eh?

Let me check around and I'll come back with a number for you pronto.

Oh, if you knew average tare weight of those tanks empty you could weigh them and tell how much Cl2 is in there, if you had a cylinder scale that is. Never mind. This way will be as we used to say - close enough for govt work. :)

----------------------------

That didn't take long. A standard cylinder is designed to hold a maximum of 150 lbs of liquid Cl2 which will occupy not more than 89% of cylinder volume @ 72 C.

I am attaching my source document which pertains to hazard of overfilling such cylinders for use with chlorinators (chlorine injectors) for water treatment.

So if you assume your tanks are full but not overfilled then you have a maximum of 1350 lbs Cl2 to deal with. Probably less. Some cylinders are still in circulation that are designed for only 100 lbs liquid CO2 but we can't assume these are such.

Say 614 Kg. Atomic weight 35.4527 so mol wt 70.954

You have max. 8648 mols Cl2 to react.

Ca(OH)2 + 2 Cl2 -> Ca(OCl)2 + 2 HCl and I think only about 50% of the calcium hydroxide will go to hypochlorite, the rest racts with the HCl formed to give CaCl2. So if this is correct then you need equal number of mols Ca(OH)2 to your Cl2 or 8648 mols slaked lime (which I believe is normally used for mixing cement or concrete.)

1 mol calcium hydroxide (slaked lime) = 74.09 g

you need 641 Kg slaked lime.

You will end up with beaucoup bleaching powder equivalent to US military DC decontaminating powder which someone might actually have a use for somewhere in...the desert.

Now, I would guess that the reaction between Ca(OH)2 and Cl2 needs to be done in a slurry with water. Let me look into that for you.

-----------------------

Looks like the calcium hydroxide need only be moist. Which is in your favor where you are.

I will dig further in Kirk Othmer and Ullman's for details. In the lab it is possible to make 90% Ca(OCL)2 but the commercial proct is typically 50%+ so to be conservative, let's stick to that figure.

Anyone want to help by double checking my calculations?
-------------------

A correction: the reference to Cl2.6H2O should be read as chlorine water, which is just a saturated solution and concentration is temperature dependent. Cl2.6H2O is chlorine hydrate, s solic stable below 10 C and above that decoposing into Cl2 and chlorine water. Of no practical import in the desert!

[Edited on 12-3-2007 by Sauron]

Attachment: 5009-OverfilledCylinders[1].pdf (191kB)
This file has been downloaded 607 times

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[*] posted on 11-3-2007 at 10:08


All that chlorine gas just WASTED ?! I want some!:D
And where does one procure such a quantity of WAR GAS?

"Actually if you added it to HOT water, you would form the chlorate which ain't in itself a bad molecule... sodium chlorate makes a good weed killer and you can sell it on the internet, pehaps to some of those pyro folks."
This would be preferable to just getting rid of it altogether.




F. de Lalande and M. Prud'homme showed that a mixture of boric oxide and sodium chloride is decomposed in a stream of dry air or oxygen at a red heat with the evolution of chlorine.
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[*] posted on 11-3-2007 at 10:49


Ahem. You don't get out much. huh? About 10 days ago someone parked a tanker of chlorine in a small town in Iraq and detonated a bomb, the resulting green cloud killed about a dozen people.

So you want to know why maybe some surplus cylinders that might in fact be aging and unsafe ought to be destroyed?

There's no shortage of Cl2 in the world, we won't run out anytime soon.

Also to characterize Cl2 as a war gas is inaccurate. Every municipality in the world uses it in abundance for water treatment; it has a multitude of industrial uses and its laboratory utility is the very reason why you want some. As a military chemical it was obsolete after WW I. It's an industrial chemical and an important one.

----------------------------

Ullmann's was no help. They did not describe manufacture of calcium hypochlorite at all, and gave a somewhat misleading equation for its formation:

Ca(OH)2 + Cl2 -> CaOCl2 + H2O

which is the old double salt fallacy.

What happens is

Ca(OH)2 + 2 Cl2 -> Ca(OCl)2 + 2 HCl
Ca(OH)2 + 2 HCl -> CaCl2 + 2 H2O

There is no Ca(Cl)OCl double salt.

The bleaching powder also contains a little calcium carbonate and calcium perchlorate.

The two equations can be combined as

2 Ca(OH)2 + 2 Cl2 -> Ca(OCl)2 + CaCl2 + 2 H2O

which is what I used above except I omitted the water out. As the object was to figure how much slaked lime was needed, rather than to get a perfect overall mass balance, I didn't think it was important at the time.
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[*] posted on 11-3-2007 at 16:49


The other way to get rid of it would be conversion to ferric chloride (FeCl3). This is another common industrial disposal method. The process involves a tank full of ferrous chloride (FeCl2) soln, and scrap steel. Bubbling in chlorine converts ferrous to ferric, which then eats away more steel, producing ferrous chloride again .. ad infinitum. Ferric choride can be dried and sold to the PCB industry.

It may be sufficient just to throw some steel into your chlorine water to generate the ferrous chloride in the first place - don't really know for sure.




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[*] posted on 11-3-2007 at 18:07


These chlorination processes are all very old technology, and the best descriptions are usually to be found in old chemical literature as opposed to current sources :P The attached file from Thorpes Dictionary of Applied Chemistry from 1921 gives many practical details about what's needed, a pallet of bags of caustic soda would be the best solution :D These files can be viewed by a freeware program:

http://www.irfanview.com

Attachment: thorpes-hypochloriteprep.zip (586kB)
This file has been downloaded 447 times





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[*] posted on 11-3-2007 at 22:01


I'm getting a headache trying to read that scan.

Anyway @Sarge is not going into the bleaching powder business, he is just trying to bind the contents of nine old cylinders into a manageable form. He and his principals will decide whether solid or liquid product is preferably. We can't make that decision. @Maya suggested solid Ca(OCl)2 is preferably to NaOCl soln and I see the logic of that.

Industrial efficiencies are not required. @Sarge needs to figure how many containers (say 55 gallon drums) will hold 1/9 of the total slaked lime I calculated. Then these need to be connected in series like drying towers, with an inlet at one end and an outlet at the other. Then connect the first to chlorine cylinder #1 and pass in Cl2 at such a rate that almost no Cl2 exits the last drum. Continue till cylinder is empty. Repeat eight more times, and he's done. I would think plastic (HDPE) Mauser style drums would work well, they are cheap and lighter than SS drums. Mild steel drums would corrode.

The calcium hydroxide should be wetted but not slurried, and the reaction conducted at ambient or slightly higher (not a problem to arrange in the desert!). I'd do all this in the open under a canopy and I'd close the final vent with a bubbler scrubber of saturated NaOH soln to monitor effluent Cl2 for purposes of establishing appropriate rate of release from the cylinder. Other than getting that established, watching to see if the soln in the scrubber turns yellow-green, and waiting for the cylinder to empty, it's time to kick back and relax.

Once the cylinders are all emptied, the drums can be sealed off and disposed of in whatever matter @Sarge and his employers/commanders deem appropriate. The exhausted cylinders should be perforated by thermite or thermate grenades or other convenient means to render them unserviceable. Then they are scrap.
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[*] posted on 11-3-2007 at 23:03


All good info. We are looking into the metal method described above. Mostly because I have more scrap metal here than you can shake a stick at!

I also have a whole collection of various drums, plastic and otherwise.

Now it is off to order chemicals.

On a lighter side, we were planning to use the once empty tanks as well, targets for tanks!

Wish I could give you some photos.... maybe later in the year.

Now it is off to try to req some chemicals. I can see it now from supply, "You want what? WTF is that?"
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