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Author: Subject: Glassware from fluorescent lamps - How to get rid of Hg?
Tacho
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[*] posted on 18-2-2009 at 03:11
Glassware from fluorescent lamps - How to get rid of Hg?


Fluorescent lamps have soda-lime glass tubes of all sizes and shapes. However, cutting them presents a hazard because of the mercury inside. How can I safely open them?

I was thinking of submerging the lamp in a sulfur-containing liquid, than drilling a small hole with a diamond bit. Hopefully the sulfur solution would be sucked in (to a certain extent) and react with the mercury.

Any suggestions for the liquid?
Any other ideas?
Links?
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bquirky
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[*] posted on 18-2-2009 at 04:16


I have wondered the same thing for quite some time. I have previously tried melting the adhesive that holds the metal end caps off and then grinding the end of the glass off. this predictably ended in a broken tube.

However i suspect it might be possible to immerse all but the end of the tube in water and heat the remaining section with a propane torch the idea being that differential expansion would fracture the glass around the water line.

Another idea that i have yet to try is wrapping some nichrome wire around the tube and running a current through it to achieve the same result.

After the tube ends have been severed it can be ground flat using the finest wet/dry paper you can find at your local hardware.


I dont know about the mercury. I cant lay claim to have thought that far ahead :) i didn't think there was much in there. people brake those things all the time. (not the right attitude i know).

Id be interested in what you find.
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not_important
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[*] posted on 18-2-2009 at 07:34


You can figure on there being less than 20 mg of mercury in a modern tube-style fluorescent bulb. The gas inside is under low pressure, an opening made under the surface of a liquid has a fair chance of breaking the tube from the rush of liquid into the tube.

Save the tubes until winter, then store them outside overnight and open them early in the morning, cutting off one end with a small high speed abrasive wheel or mini air-abrasive gun. Drop in a mixture of a half gram of zinc dust with 5 grams of find sand, stopper the open end of the tube. Leave it for a few days, then repeatedly invert the tube so as to run the zinc-sand mix over all the interior. Repeat each day for several days, Pour the mix out into a collection jar, pour in another gram or so (0,1 g Zn + 1 g sand), shake it well, add to collection jar. Repeat with just plain sand. After you get a lot collected you can leach the mix with HNO3+H2O to dissolve the Zn, Hg, and some of the phosphors. Follow standard inorganic analysis to precipitate mercury as HgS and bottle it for future use.

In general it's more trouble than it's worth. Thin walled soda-lime, very easy to break and not very good with heat. The exceptions are:

1) You're a hippie making an algae farm while spending as close to zero money as you can get, and have little else to do.

2) The tubes are germicidal lamps, which have fused silica bulbs.
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chief
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[*] posted on 18-2-2009 at 14:26


New glassware costs only 2-3 EUR/kg ; for various sizes of tubes, for standars glass. Quartz-glass is expensive ...
Maybe even can be got cheaper than these 2 EUR ...

[Edited on 18-2-2009 by chief]
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Aqua_Fortis_100%
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[*] posted on 18-2-2009 at 17:17


I opened fluorescent lamps just once, to make a improvised distiller.

http://i242.photobucket.com/albums/ff176/tnitrato/P9060028.j...

http://i242.photobucket.com/albums/ff176/tnitrato/P9060029.j...

Inside its a kind of very resistant fluoropolymer tubing..

Simply leached aluminium from ends with NaOH solution in outdoors, removed the glue and tried to cut with a diamond tool (I was able to cut it, but cracked in some points).
To remove the pigment I washed with muriatic acid then water.

I know that I was exposed to mercury even using gloves, dont inhaling adjacent air and such, but I did this just once..
All the other used fluorescent lamps I store thinking to send to recycling center in future (but paciently waiting they make such lamp recycle center here).
With the greater interest about green chemistry, recycling technologies , etc I think that things like this: http://www.youtube.com/watch?v=iHWn0sX09Jo will soon be fully spread everywhere..
BTW, the small transistorized fluorescent lamps are interesting to get usual components and make fun devices like Joule Thief and other things.

@Tacho: veja quanto de Hg eles pegam em SP no centro de reciclagem especial: http://www.youtube.com/watch?v=P9u_xPWgT50

[Edited on 18-2-2009 by Aqua_Fortis_100%]




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chemrox
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[*] posted on 18-2-2009 at 23:59
bad idea


Using old light tube glass to make labware is not at all feasible and given the low cost of labware on ebay these days it's a monumentally bad idea. Sorry, but use your energies more productively.
Cheers, CRX




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Tacho
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[*] posted on 19-2-2009 at 03:37


@bquirky: To cut glass I use a small diamond disk on a Dremel-like tool (small, cheap chinese 12V version) under a stream of water. It takes patience, but gives no surprises. I intent to test the hot wire method in the future.

@not_important: Thank you. The Zn/sand is a good idea, specially because one of the videos linked by Aqua says that 90% of the mercury is adsorbed on the phosphor powder, and the sand would help remove the powder. Wouldn't sulphur be as good as Zn? I also did not know that germicidal lamps use silica. That is indeed a good reason to recicle those at home.

@Aqua: Interesting links, thanks. I would have used PVC instead of glass in that condenser though.

As for the many posts claiming is simply a bad idea because you can find cheap glassware on e-bay, I disagree. It may be a bad idea because of the mercury, and that is why I created this thread, but soda-lime glass is very easy to work with. it only takes a gas blowtorch, and fluorescent lamps are everywhere.


Back to the liquid idea:

Would a solution of sodium bisulfite react with metalic mercury to form some insoluble salt like sulfur does?
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not_important
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[*] posted on 19-2-2009 at 06:05


Sulfur and mercury are fairly slow to react, the amalgamation with zinc goes much more quickly. Sulfur is good for treating floors after a mercury spill cleanup, where it serves to in effect seal any remaining mercury in.

Only the "this lamp causes blindness and cancer" type germicidal lamps, the ones with clear bulbs, are silica.
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chief
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[*] posted on 19-2-2009 at 12:18


But maybe these glass-tubes might be tempered so to get less in diameter and thereby a useful wall-thickness ...
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Tacho
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[*] posted on 20-2-2009 at 03:08


THE LIQUID: Does sodium bissulfite react with mercury? What about colloidal sulfur? Maybe a sulfur slurry. Or a zinc dust slurry.

Any suggestions of liquids that react with mercury to form INSOLUBLE precipitates would be appreciated.

The thin walls may be an advantage if you don't need mechanical strenght. They make the glass easier to work (most of the time) with and increase thermal shock resistance. Incandescent lamps go through pretty good thermal shocks all the time without breaking.
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not_important
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[*] posted on 20-2-2009 at 08:25


NaHSO3 does nothing interesting for your application.

Polysulfides are the best bet for getting a reaction, but they will just leave HgS embedded in the phosphor on the tube interior and still aren't real quick.

The length of opened fluorescent tubes work against them, they readily fracture from minor stresses typically applied to condensers and fractionation columns.
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Globey
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[*] posted on 20-2-2009 at 08:29


If you have to do this, do it outdoors, and preferably in the cold. Remember: Dilution is the Solution too Pollution (NOT!). You might want to consider using elemental sulfur to make an artificial cinnabar. But really. I've thought of doing this, and there really is no justification. Sure, a T8 might fit into a T12, and there you could have a straight jacket condenser, but why not just use CPVC. And for distillations/reflux where the CPVC is prohibited, you can use copper. The one condenser I made consisted of some virgin (heavy walled) polytef tubing, enclosed in some larger diameter CPVC. The idea was to have something as (or more) resistant than boro-silicate, yet not as easily breakable as glass.
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chief
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[*] posted on 20-2-2009 at 09:23


Just do it outdoors when the wind is strong ; most people have more mercury in teyr amalgam-toothfillings than there is in 100 such tubes. It's probably more expensive environmentally to do all that "safe disposal"-stuff mentioned here.
Just find a way to get out the phosphor easily - either some dilute acid, ore some soda-boiling, or maybe just sand-shaking ; then proceed all the bulbs you have and get it past you.
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Tacho
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[*] posted on 20-2-2009 at 09:27


A polysulfide solution seems to be what I was looking for. Easy to make and is already commonly used to treat wastes that contain mercury. It doesn't have to be quick, since the bulbs can stay soaked for a week or two. The phosphor powder along with the HgS will be washed away and discarted.

It seems to me that this would be a safe and environment-friendly solution.

Thanks.

edit: The mercury toxity discussion seems to be endless. I'm tired of it. I'll just stay on the safe side to be sure. If the procedure is as simple as I think, there is no reason not to do it. Hope to post about it soon.

[Edited on 20-2-2009 by Tacho]
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Globey
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[*] posted on 21-2-2009 at 21:46


The sulfide is a great idea as the mercury can't easily cause harm in that form. Same reason I wonder why people are so worried about eating some of the larger game fish high in mercury content. By the time the mercury has done the damage to the fish's protein, it is so tightly bound with the sulfur, that it is almost inert. Also, elemental mercury is fairly non-toxic when injected (by mouth). The old blue pill "Mercury Mass" was used to treat constipation years ago. But then again, they used to use arsenic to treat syphilis!
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not_important
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[*] posted on 21-2-2009 at 22:56


Quote:
Originally posted by Tacho The phosphor powder along with the HgS will be washed away and discarted.

It seems to me that this would be a safe and environment-friendly solution.


I find the phosphor mix more interesting than soft glass tubes; especially with the Hg, although with only 10 mg or so per tube you need hundreds of discarded tubes to get useful amounts of it.

I think you'll find your local environmental laws take a dim view of washing even fractional gram amounts of mercury compounds down the drain. I believe that some bacteria can convert HgS to more mobile compounds, using it in a fashion to other sulfide/sulfur oxidising biology.
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[*] posted on 22-2-2009 at 05:39


(offtopic) I got curious enough with n_i's mention of bacteria possibly mobilizing Hg... then I found these two abstracts... :o

sparky (~_~)




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Paddywhacker
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[*] posted on 28-2-2009 at 16:11


I've thought of this for chromatography columns. Decent-sized preparatory columns.

But wondered about the glass. Can you flame smoothe the edges without it cracking?

Can you soften and draw it out?
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[*] posted on 1-3-2009 at 06:08


It's thin glass as it is, why would you possibly want to draw it out any more?
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Tacho
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[*] posted on 2-3-2009 at 05:45


I believe the diameter can be reduced without "drawing" it, simply by turning it and shaping with a tool while hot. But this requires some skill, of course.

I have made a polysulfide solution by boiling 0,5g of sulfur and 2,0g of NaOH in 20ml of tap water. The sulfur was initially wetted with a few drops of methanol. The result was an orange solution.

I understand that the polysulfide solution will release very POISONOUS H2S if acidified. Is that right?

I mixed a spoonful of portland cement based mortar with just enough of the polysulfide solution to make a paste. The mix was made in a polyethylene bag. It hardened normally overnight. It seems like a good way to dispose the polysulfide+HgS because the cement matrix is very alkaline, preventing the releasing of H2S, and it will keep the HgS safely embedded for a few thousand years. The plastic bag also helps.

I dismantled a compact fluorescent lamp (did not break the glass) and was surprised to see inside a little droplet that seems to be metallic mercury. It's very tiny, much smaller than a pin's head. I always though the mercury was adsorbed everywhere inside the bulb and could not be seen.

[Edited on 2-3-2009 by Tacho]
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[*] posted on 2-3-2009 at 10:09


Quote:
I dismantled a compact fluorescent lamp (did not break the glass) and was surprised to see inside a little droplet that seems to be metallic mercury. It's very tiny, much smaller than a pin's head. I always though the mercury was adsorbed everywhere inside the bulb and could not be seen.

The mercury isn't "absorbed", it's a vapor that fills the tube. There's more mercury in there than can be vaporized at room temp, so some of it is liquid. When it's fully warmed up it should all be vaporized. That's why florescent lights are dimmer when you first turn them on, and take a few minutes to warm up to full brightness.
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Tacho
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[*] posted on 3-3-2009 at 03:10


I meant aDsorbed, not aBsorbed. Mostly by the phosphor powder, I think.

The germicidal lamps I have, with transparent glass (no phosphor), don't seem to have any elemental mercury inside, even when cold.
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