Just how explosive is 99% benzoyl preoxide?

[masterofnone]

I have a pound of 99% pure benzoyl peroxide powder in one of my labs. It looks like it's from the fifties or sixties. We're looking into disposal, which looks like it will involve several thousand dollars, bomb suits, and a police escort.

Meanwhile, here it sits in a refrgerator. I see from the MSDS that it auto-ignites at 80C, and can explode due to shock, heat, friction, static, or just spontaneously.

How big a boom would this make? Are we talking about destroying a room, a building, or the whole block?

[Green Cymbeline]

Wow I had no idea that benzoyl peroxide was so explosive! How scary! What was it used for in your lab? Is it really going to cost thousands to dispose of it? Who disposes of it, and how do they do it?

[masterofnone]

Originally Posted by nyctea scandiaca

Wow I had no idea that benzoyl peroxide was so explosive! How scary! What was it used for in your lab? Is it really going to cost thousands to dispose of it? Who disposes of it, and how do they do it?

I didn't either until I went through some old chemicals to dispose of them and looked at the MSDS. I've no idea what it was used for, as it's probably from before I was born. Our normal haz waste guys assumed I'd meant it was a solution that was 99% water, and said they'd take it. Then they showed up, saw that it really is 99% pure benzoyl peroxide powder, and would not touch it. We're looking into disposal, but I don't know the exact cost and method yet. Someone is supposed to show up tomorrow to take a look at it.

[Santo Rugger]

Benzoyl peroxide has a TNT equivalent of about 25. One stick of dynamite is about 1/3 lb TNT equivalent. So you've got about 75 sticks worth of dynamite, or a box and a quarter.

Make sure to keep that refrigerator plugged in! Regardless of the initiating factor (heat, shock, friction), the only way for DDT (deflagration to detonation transition) to occur is for a localized hot spot to generate heat faster than the bulk of the material can transfer it away.

Have you called the local fire department? They may have access to a HazMat team that has the tools to diffuse this situation (no pun intended) for less than a few grand. Let us know how they end up disposing of it, though!

[Busy Scissors]

Normally, I would destroy that chemical exactly as it directs on the safety data sheet, stirring with aq NaOH in a fume hood behind a blast shield. I'm an experienced chemist though, DON'T try doing this yourself if chemistry isn't your line of business. THis method is recommended in the hazardous laboratory chemicals disposal guide, which you can actually read on google.

This would not be a big deal if the peroxide was a recent unwanted purchase. What makes it more awkward is that the peroxide sounds like it is very old, which can mean corroded containers and the like that can catalyse decomposition. Without seeing the state of the material I can't say what I would do, it is best to exercise caution. Can you ask a chemist who knows what they're doing to take a look at it? They should be able to give you better advice on whether a disposal is in order, or whether the cheque book needs to come out to pay the hazmat chimps to take it and burn it for you.

[matt]

Originally Posted by masterofnone

We're looking into disposal, but I don't know the exact cost and method yet. Someone is supposed to show up tomorrow to take a look at it.

The MSDS you linked to suggests it can be destroyed using a 10% solution of caustic soda and flushed down the drain.

Originally Posted by Santo Rugger

Benzoyl peroxide has a TNT equivalent of about 25.

I find this highly unlikely. TNT has a explosive energy of slightly above 1000 calories/gram, say 4.2 kJ/g. The following pdf gives the reaction energy of benzoyl peroxide as 3.47 kJ/g in a "blasting cap test", where it appears a sample is initiated by blasting cap. Table 1, page 14 of http://archives1.iomosaic.com/whitep..._screening.pdf

Originally Posted by Santo Rugger

One stick of dynamite is about 1/3 lb TNT equivalent.

Practically meaningless. Dynamite comes in a range of types, strengths and sizes of cartidge.

In terms of energy, it looks like you have the equivalent of something less than a pound of TNT. Energy doesn't directly equate to explosive power however - it doesn't tell you anything about the brisance. BPO is used in pyrotechnic effects and so is unlikely to generate pressures on the level of TNT.

[Hampshire]

Since Benzoyl Peroxide is the active ingredient in acne creams (usually diluted down to 3-5%) it seems like with the right solution (10% caustic soda like Matt suggested) you could slowly dilute it and rinse it down the drain.

[Duckster]

Originally Posted by masterofnone

Someone is supposed to show up tomorrow to take a look at it.

It's one thing to have it sit there all by itself and no one knew it was there. But now that it's existence is known, the longer it takes to resolve the problem, the greater the chance "someone" will let the cat out of the bag.

Do you really want to risk getting a phone call from a local TV station with a reporter asking a simple question, "why is it taking so long?"

After all, February is ratings sweeps month. Some local TV reporter can get quite a bit of mileage, and a local Emmy award, just reporting on the foot-dragging.

[WarmNPrickly]

Originally Posted by TheCockyWatchman

Normally, I would destroy that chemical exactly as it directs on the safety data sheet, stirring with aq NaOH in a fume hood behind a blast shield. I'm an experienced chemist though, DON'T try doing this yourself if chemistry isn't your line of business. THis method is recommended in the hazardous laboratory chemicals disposal guide, which you can actually read on google.

Given that this is a really old bottle and the material has likely solidified into a huge mass, I wouldn't touch it. Quenching it slowly would involve trying to chisel away at the mass. I've had a perchlorate go off in my hand from just that. Having been the guy responsible for all of the solvent stills in grad school, I have little fear of quenching reactive substances, but this one would be way out of my hands.

[masterofnone]

Originally Posted by The Cocky Watchman

Normally, I would destroy that chemical exactly as it directs on the safety data sheet.

Had we not asked our normal hazmat folks to haul it away, one of our chemists could have made it dissapear using that method. However, we are not licensed to treat hazmat, so that would have been illegal, and I'm not sure we have a blast shield.

Originally Posted by The Cocky Watchman

What makes it more awkward is that the peroxide sounds like it is very old, which can mean corroded containers and the like that can catalyse decomposition.

It's in a half decomposed plastic bag inside a cardboard tube with a label that looks to be ~50-60 years old. It's also beige crystals, instead of the white descibed in the MSDS, so we're calling in a hazmat pro who knows more than the "hazmat chimps" who usually take our hazmat away.

[Santo Rugger]

Originally Posted by matt

<snip> I find this highly unlikely. TNT has a explosive energy of slightly above 1000 calories/gram, say 4.2 kJ/g. The following pdf gives the reaction energy of benzoyl peroxide as 3.47 kJ/g in a "blasting cap test", where it appears a sample is initiated by blasting cap. Table 1, page 14 of http://archives1.iomosaic.com/whitep..._screening.pdf

The source I was using said "25 to 30 percent", but percent was on the next line. Divide all my numbers by 100, and our answers become much more similar. There's not enough for that guffaw!

Practically meaningless. Dynamite comes in a range of types, strengths and sizes of cartidge.

True, but I think using "sticks of dynamite" to equate explosive energy to a layperson is more effective than trying to explain TNT equivalence. Not because they wouldn't be able to understand it, but I imagine few people actually having seen a TNT explosion, whereas more can imagine what a stick of dynamite looks like and how much damage it would do.

In terms of energy, it looks like you have the equivalent of something less than a pound of TNT. Energy doesn't directly equate to explosive power however - it doesn't tell you anything about the brisance. BPO is used in pyrotechnic effects and so is unlikely to generate pressures on the level of TNT.

Agreed. From this CatalystSystems link (specifically Table 1, page 3), it also looks like it's pretty hard to get it to detonate at all. In the case study presented, the explosion happened because the dryers used to purify it got too hot.

[masterofnone]

Originally Posted by Santo Rugger

From this CatalystSystems link (specifically Table 1, page 3), it also looks like it's pretty hard to get it to detonate at all.

That seems to be the opinion of the hazmat guy we've got coming in to check it out. Given that it's in a 4C refrigerator in an secure area, he just told us to leave it alone until he can assess the situation tomorrow.

In the case study you cited, I can't believe they didn't drain the water from the jacket after the contents had reached the desired temperature. It seems to be inviting an explosion to have the water in the jacket 2C above the point of spontaneous combustion of your product.

ETA: Your sticks of dynamite analogy works well enough for me, especially now that we're down to approximately equivalent to 3/4 stick.

[Sigene]

As a first year science teacher I had a pile of old picric acid in the cabinet that had to be close to 30 years old. I called the highway patrol. Bomb squad was there the next morning.

Course, my superintendent was a little pissed, but too damn bad. Call your nearest police bomb squad.

[GameHat]

For what it's worth;

I work with high purity Benzoyl Peroxide (BPO) nearly every day. It's used commonly in my industry to initiate free radical polymerization in composites.

As peroxides go, BPO is comparatively safe. Just keep it cold and you've got no worries. 4C is perfectly fine and well below either the flash or autoignition temp.

You probably don't need to rush to call in Hazmat; just find a cheapish place that does chemical disposal. As long as you are storing BPO properly (COLD) then you are not putting anything in danger and it could probably sit there for 50 years.

How do we dispose of old BPO? We react it! Typically BPO would be used at a 1% - 2% mass concentration to initiate resin curing. We frequently have dozens of pounds of "junk" resin for disposal that we just set off with BPO. The end result is a solid mass of plastic that is non-hazardous in any way and can go in regular trash.

Like I said - in your case, a rush to call in a HAZMAT team is unwarranted as long as you store the BPO properly. Find a cheapish place to do chemical disposal and you are fine.

[masterofnone]

Update:

VT requires a permit to dispose of it. We're having our hazmat people get the permit and deal with it. At first they wanted to bring in a bomb truck + robot to move it out and detonate it, but they decided to get a permit and neutralize it here. They say we're fine as long as it's cold and secure.

[Really Not All That Bright]

Originally Posted by Santo Rugger

it also looks like it's pretty hard to get it to detonate at all. In the case study presented, the explosion happened because the dryers used to purify it got too hot.

Given that it's been sitting in your lab for forty years and presumably hasn't blown up yet, how dangerous could it really be?

[Solfy]

Originally Posted by Really Not All That Bright

Given that it's been sitting in your lab for forty years and presumably hasn't blown up yet, how dangerous could it really be?

The most dangerous chemicals are those who have been sitting around for ages. While it's still sitting around, your point holds - there's probably little danger of allowing it to continue to sit around. Unfortunately some chemicals form degradation products while they're sitting around that are inherently unstable to movement - they can go BOOM when they're moved even the little bit necessary to remove them from a fridge down the hall to the disposal truck.
Frequently these byproducts are slow to form (which is why the longer things have been sitting, the less you know about what's really in them) and hard to detect in a big, solid sample (indicator strips are available to test for things like peroxides in unstable solvents).
Is it likely? Probably not.
Do you want to be the one to gamble and lose and blow up the department?
Benzoyl peroxide roulette! Fun and excitement versus big hazmat fees!

[Santo Rugger]

Originally Posted by Really Not All That Bright

Given that it's been sitting in your lab for forty years and presumably hasn't blown up yet, how dangerous could it really be?

The problem isn't with the BP sitting there. The problem is with trying to move and dispose of it. Right now it's cool, and not in any danger of developing hotspots. But, when you take it out of the fridge, it's going to start warming up, and when you move it, there is going to be friction between granules. Even if it doesn't detonate, it can still deflagrate, which isn't a fun thing to be near unshielded.

The difference is that the combustion in a detonation takes place faster than the bulk speed of sound, while deflagration is slower. It's still a lot faster than a fire, and needs to be treated with respect. Three examples of deflagration are gunpowder, rockets, and fireworks (pyrotechnics). Being close to a deflagration with proper shielding, though, is a blast!

Originally Posted by Sigene

<snip>Course, my superintendent was a little pissed, but too damn bad. Call your nearest police bomb squad.

Lots of times, the bomb squad is part of the HazMat unit. When there's a suspicious package, and you don't know if it's a bomb or some type of nerve agent, it helps to have personnel who are multifaceted.

[Really Not All That Bright]

Originally Posted by Solfy

Do you want to be the one to gamble and lose and blow up the department?
Benzoyl peroxide roulette! Fun and excitement versus big hazmat fees!

Have you read my posts? Of course I want to be that guy!

NB. My attitude toward chemistry is perhaps shaped by the teacher I had in school who blew his right hand up while showing up how to make gunpower and now can't dial phone numbers with 1, 4 or 7 in them....