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Author: Subject: How to scrub ethyl acetate vapors before releasing into the outside air? Hundreds of neighbors are complaining.
beerwiz
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[*] posted on 28-12-2018 at 14:21
How to scrub ethyl acetate vapors before releasing into the outside air? Hundreds of neighbors are complaining.


I'm handling multiple gallons of ethyl acetate, acetone, and toluene per filtration, separation, etc. The fume hood removes all the vapors but I live in a densely populated urban area and hundreds of neighbors are complaining about the smell of solvents and of symptoms like burning eyes and difficulty breathing.

What can I do to prevent the vapors from reaching the neighbors/exiting into the atmosphere outdoors?

[Edited on 28-12-2018 by beerwiz]
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Sigmatropic
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[*] posted on 28-12-2018 at 14:54


By not evaporating large quantities of volatile organic compounds in residential neighborhoods.
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beerwiz
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[*] posted on 28-12-2018 at 14:59


Quote: Originally posted by Sigmatropic  
By not evaporating large quantities of volatile organic compounds in residential neighborhoods.


I'm not evaporating anything intentionally, I do large scale filtrations and separations but the solvents are volatile and large amounts of vapors are released while handling them.

It occured to me that if this is done on a very windy day, I may get away with it because the strong wind will disperse the VOC's almost instantly.

[Edited on 28-12-2018 by beerwiz]
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DoctorOfPhilosophy
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[*] posted on 28-12-2018 at 15:16


Can you do the work in a glove box? You can use nitrogen gas to purge the glove box if you're worried about an explosion.
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beerwiz
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[*] posted on 28-12-2018 at 15:23


Quote: Originally posted by DoctorOfPhilosophy  
Can you do the work in a glove box? You can use nitrogen gas to purge the glove box if you're worried about an explosion.


There's no explosion risk other than possible ignition of the solvents. It's too large for a glovebox, we are talking handling 20 gallons of solvent at a time. I wonder if the VOC's will be eliminated by putting a large activated carbon filter at the exit exhaust.
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DavidJR
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[*] posted on 28-12-2018 at 15:25


During filtration etc are you leaving large containers of solvent open to the air? If so then loosely covering it with something would greatly reduce evaporation.
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beerwiz
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[*] posted on 28-12-2018 at 15:50


Quote: Originally posted by DavidJR  
During filtration etc are you leaving large containers of solvent open to the air? If so then loosely covering it with something would greatly reduce evaporation.


I keep covered containers that can be covered. Most of the smell is generated when pouring from one container to the other and during the buchner filtration when the vacuum pump dissipates all the VOC's all over the place.

I wonder if a very large ductless fume hood is the solution?
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DoctorOfPhilosophy
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[*] posted on 28-12-2018 at 16:21


Maybe seal up the garage with plastic film and duct tape and wear a SCBA mask? Ok- maybe that's a bit extreme.

How about running the fume hood vapours through a large dehumidifier? I don't think a carbon filter will work for very long.
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DavidJR
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[*] posted on 28-12-2018 at 16:26


You could maybe set up some sort of activated carbon filter on the outlet of the vacuum pump.
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[*] posted on 28-12-2018 at 18:38


Why are you using of gallons of solvents?

Why not have a sort of cold finger for recovering your solvents after they evaporate. Run the output of your fume hood through some ice water.

The alternative is the find away to burn it as it leaves the hood.

You could also buy or make a large rotary evaporator: Get a 10 L flask, water bath, vacuum pump, and condenser. The whole set up would only cost a few hundred dollars; which is far less than a fine from the EPA.




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beerwiz
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[*] posted on 28-12-2018 at 19:32


Quote:

Why not have a sort of cold finger for recovering your solvents after they evaporate. Run the output of your fume hood through some ice water.


That's not practical, but if I can mod a refrigerated dehumidifier by leaving the refrigeration part and removing the heating element, that will work. The vapors will condense and collect in the tray.

Quote:

The alternative is the find away to burn it as it leaves the hood.


The solvents are flammable, it's a fire hazard to burn them.

Quote:

You could also buy or make a large rotary evaporator: Get a 10 L flask, water bath, vacuum pump, and condenser. The whole set up would only cost a few hundred dollars; which is far less than a fine from the EPA.


I have a setup like that but I'm not distilling the solvents, I'm just handling them when filtering the solutions and when separating them with the separatory funnel. Since it's a large volume, the vapors stink up the whole neighborhood.

My only options as I see it are a carbon filter-air cleaner with high CFM and/or a modified dehumidifier with the heating part removed.

I'm sure I can run the cabon filter only setup attached to my fume hood on a VERY WINDY day and no one will notice any smells.

Any other ideas?

[Edited on 29-12-2018 by beerwiz]
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[*] posted on 28-12-2018 at 19:45


The dehumidifier is an excellent proposition but do you think that the heating element on off the shelf units will ignite the remaining solvent vapors that pass through it?
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VSEPR_VOID
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[*] posted on 28-12-2018 at 20:11


The only reason you are using gallons of solvents that would seem reasonable would be if you were preparing drugs. Dont you have posts about extracting alkaloids? I dont care either way but at least spill the beans on what you are doing. Also please dont gas your neighbors well doing it.



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monolithic
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[*] posted on 28-12-2018 at 21:17


20 gallons of solvent at a time? Are you running a pilot plant out of your apartment/garage? That's a very, very large volume even for large scale amateur chemistry.
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[*] posted on 28-12-2018 at 23:37


You may need to find another location to do your work.
Not going to work out if you are affecting the neighbors
in a negative way.
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[*] posted on 29-12-2018 at 00:31


I agree with the others on this, you should find another locations.
However if you dont want to take that advise you could do it while its raining.




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[*] posted on 29-12-2018 at 02:56


carbon filters are not some type of magic thing that removes every smell in any quantity. if all your neighbor can smell solvents and this even leads to physical symptoms, we are not talking about a few grams of VOC, you would need a small industrial scale filter.
but the important question, why are you using 20 gallons of solvent at a time? this is very overkill for an amateur, at this scale you need a plant, away from homes, an air filtration system, a solvent recovery system, huge glassware and equipment. how do you manage your waste? for us disposing of 1 or 2 liters is not really a problem but 20 gallons?
before working at this scale you should have thought about this, especially if you are doing illegal compounds, hundreds of neighbors complaining about solvent smell is enough to alert everybody





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[*] posted on 29-12-2018 at 03:21


Thanks Sigmatropic your reply was the first thing I read today, it made me laugh. What your filtering is of absolutely no consequence as the question is apt. My suggestion is for you to take a picture of the filtering apparatus you are using or at least a description of what type of funnels, both Sep.
and filtration as well as receiver. Furthermore I would suggest a little ingenuity, transfer pump cover your funnel and run filtration with positive pressures; after which run exhaust fumes through a preexhaust train of charcoal in one, water in another and the last chilled to ultra low temp (liquid N2, CO2 slurry) only then allow fumes to pass through your hood exhaust. This might help but ultimately one has to expect some consequences when operating at manufacturing quantities (no neg. implication intended). That's my limited two cents.
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[*] posted on 29-12-2018 at 06:50


Burn it. Use several flashback arrangements & let the fumes go to into a combustion engine of some sort.
Or a furnace.

Carbons only going to absorb & condense some fumes before becoming wet & it stops working.
Using a Xtra cold freezer & some sort of condenser ( car aircon condenser, 1 cubic foot aluminium radiator ) in the frost free, down to minus 18°C, freezer.
Pipe the liquid output back nto a drum.
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[*] posted on 29-12-2018 at 08:59


Not sure where you are, but in my state doing anything that releases any "appreciable" solvent or chemical vapor into the air is a state EPA/DENR violation with $1000's in fines and likely jail time, if you are found to be operating a business without the appropriate permits, licenses or bribes to various politicians. That is totally up to you, but I would be careful, as if the police or others get some complaints, they will ASSUME that whatever you are doing at the scale is illegal and then the fines will be the least of your worries. Even legitimate businesses get dinged by the EPA/OSHA/etc often, but government type people loves to show that they are protecting the world from polluters right now, so I would be very careful if I was doing anything with chemicals in a residential area, even on a small scale, and I would never consider doing anything there on a large scale.

You will not be able to contain gallons worth of solvent vapors with simple equipment, that is why real chemical facilities cost a lot, they have special equipment for this. While this type of activity was ignored or overlooked back in the 1950-70's, it has not been allowed pretty much since then, due to the Superfund type issues that came of the previously slack rules. And any attempt to contain vapors with plastic sheeting, is likely to make static and blow the place up, which is why OSHA does not allow that type of process. PS, Fire codes often limit the amount of solvent not in a fire proof cabinet to 20 L per room.

[Edited on 29-12-2018 by Dr.Bob]
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[*] posted on 29-12-2018 at 10:14


So far I've concluded that there are two simple things that can be done:

1. Use the fume hood and vent outdoors on very windy days only, nature has the best ventillation system.
2. Transfer, don't pour. Pouring releases lots of VOC's, instead use a transfer pump to transfer from one vessel to another. It won't eliminate the smell but it will greatly reduce it. The strong wind outside will take care of the rest.

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[*] posted on 29-12-2018 at 10:29


Quote: Originally posted by eesakiwi  
Burn it. Use several flashback arrangements & let the fumes go to into a combustion engine of some sort.
Or a furnace.

Carbons only going to absorb & condense some fumes before becoming wet & it stops working.
Using a Xtra cold freezer & some sort of condenser ( car aircon condenser, 1 cubic foot aluminium radiator ) in the frost free, down to minus 18°C, freezer.
Pipe the liquid output back nto a drum.


I second this. The risk of fire/explosion is low since the fumes are diluted in the air. You could still be careful.

The condenser is your best bet, but you will need a lot of cooling which will be energy intensive.




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stoichiometric_steve
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[*] posted on 29-12-2018 at 10:38


If those quantities you're handling emit that kind of stink, you're just doing it all the wrong way.

Vacuum filtration does not usually give off vapours in large amounts unless you use that kind of rotary vane vacuum pump you talk about in another thread, which is probably what you're doing. Ethyl acetate might start to evaporate with a strong diaphragm pump but will cool itself down to a point where almost no more vapours come off, unless you're sucking a lot of air through.

Didn't you say earlier you're operating a -120deg cold trap?
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[*] posted on 29-12-2018 at 11:03


I think I've also seen a gasoline container somewhere with a big main tube for the liquid fuel, and a small vent tube mounted on top of it. The idea is that when you pour the gas into a motor's gas tank, any vapor from the tank is drawn up into the can. Supposedly, that not only reduces the amount of fumes you breathe but also keeps the remaining gas from evaporating in the can (since the air in the head space is already almost saturated with gas vapor) I don't know how much this kind of setup would help in your situation though.

My guess is that the worst of the fumes come from the vacuum filtration. After all, you're pulling air through a porous frit soaked in solvents. Even if you already have a -120C cold trap, maybe you can go to the next step-putting the vacuum pump exhaust through a bubbling stone in -80C acetone? Feeding it through something that will react with the vapors? I want to say shove the vac. exhaust past the water trap of a sink, but that's just worsening the issue by confining the fumes in a sewer, not getting rid of them...

Of course, it goes without saying that handling 20 gallons of any voc at a time has its hazards, other than making the neighborhood suspicious of you. Drop one of those containers and you will likely be poisoned or incinerated before you can move to fresh air and change your clothes. And if you somehow get a flash fire inside a partially filled can, you will spill it, spectacularly. Now imagine that in your lab with close to two orders of magnitude more liquid! I assume you're knowledgeable about all this, but it can't hurt to make sure.

The ideal fix is to build the pilot plant (if that's what it is, and it's gonna be permanent) in an appropriately zoned area, with an almost completely closed apparatus, with the main opening to the air being a flare stack with some really good flashback arrestors, and tons of fire suppression equipment for if (when, if it's like many refineries) something blows up. But that's probably not practical in this case.

We're all still wondering why you need so much solvents. Knowing why would help us help you. Are you dissolving huge batches of some product? Or is it something with horribly low solubility? Is it possible to use a solvent for which the product has higher solubility? Or one with less vapor pressure? Telling more details on why you are pouring so much solvents will probably be the first step to getting any good advice.

Sorry for the long post. I may not be qualified to answer, but again nobody is without knowing more details. I'm throwing these ideas out there, in case I've thought of an idea no one else has yet.

[Edited on 29-12-2018 by Vomaturge]
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[*] posted on 30-12-2018 at 11:21


I will say, learn to deal with the vapors and get the hell away from a residential area that will affect hundreds.
Seriously?
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