jsc
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Absorption of mercury vapor
I am thinking about making a mercury barometer and would like to cover the open end (the basin) with a mercury-vapor-absorbing filter to minimize the
release of mercury vapor. I have two questions:
(1) What would be the most effective type of filter? My main two candidates are an ordinary activated charcoal and silver gauze. Silver gauze would be
made by dissolving silver in nitric acid, drying it onto a disk of cotton fiber (cotton ball) and then using a torch to burn away the cotton, leaving
a silver gauze.
(2) What kind of absorbtion rates can I expect?
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Chemosynthesis
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Interesting questions. I'm not sure, but think this article may help (pay walled):
http://www.sciencedirect.com/science/article/pii/00179310639...
Have you considered adding an iodine stage?
http://www.ohiolumex.com/products/mercury_vapor_filter_scrub...
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IrC
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Question 2 I would think cannot be answered due to the many variables in how you build your filter. Your silver gauze idea is not going to work well,
how much Hg do you think will be taken up as the vapor passed through a thin sheet VS how much raw Hg vapor passed on through unaffected. You need the
vapor to pass through enough medium to stop it all. I was wondering about milling activated Carbon with Sulfur dust and then creating a filter with
that. If some kind of metal sponge like material could be impregnated with the C-S mixture into a column or similar device then the Hg would see more
opportunity to be taken out before it could reach the outside air.
"Science is the belief in the ignorance of the experts" Richard Feynman
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jsc
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Obviously I can test any filter. Just put a cold trap at the outlet and let it run for a week to see how much mercury is produced, then insert the
filter and run it for another week and compare. So, if there is half as much mercury, then it is 50% absorbption, etc.
I have heard that silver is pretty good at absorbing mercury.
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jsc
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Chemosynthesis, I know halogens like iodine are superior absorbers because they actually react with the mercury, but I do not want to use a halogen
because they are volatile. Not only would this require renewing the filter periodically, but then I would have halogen vapors being emitted, which I
do not want.
It has to be a purely passive filter.
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IrC
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Silver is not nearly as good at taking Hg out of the picture as is S, the fact is flowers of S is the most common cure for Hg spills into carpet or
cracks and crevices in a room. Obviously cost is a factor as well. Also I would have to wonder about surface area and time of contact as Hg vapor
passed by a small Ag particle in your approach. I am aware you could measure it on question 2, but you were asking us and I was pointing out it is
unlikely anyone here could answer it with zero information concerning conditions in your filter.
"Science is the belief in the ignorance of the experts" Richard Feynman
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Artemus Gordon
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<a href="http://en.wikipedia.org/wiki/Mercury_(element)#Toxicity_and_safety">Wikipedia</a> says that powdered sulfur or zinc can be used
to collect spilled mercury, so I guess filter paper covered with a thin layer of one of these would probably work to catch most of any Hg vapor
emitted, but just how much vapor are you expecting? Mercury boils at 356.73 °C so there should be very little vapor coming off it at room temp. In
fact, the very operation of a barometer assumes the empty space at the top of the mercury column is close to a perfect vacuum. Unless you plan to keep
your barometer in your house for many months, I wouldn't think you would get much exposure from it.
In high school, many many years ago, I made manometers for a physics project with glass tubing and a bottle of mercury, at the request of the
instructor. So I was exposed to mercury vapor and on my ungloved hands for a week. Admittedly we were not as concerned about toxic exposure in those
days, but I didn't suffer any ill effects from a much greater exposure than I think you are likely to receive.
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jsc
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Yes, thats true, the volatility of mercury is 0.056 mg/hr/cm², so the barometer will just produce 1 or 2 milligrams of vapor every day, but if
possible I would like to reduce that further.
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Chemosynthesis
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Ah. Well, you could try a mixture of silicon dioxide silver nitrate. Marketing claims Mercurisorb is superior to sulfur, silver, and halogens and is
mostly this. MSDS PDF link: http://www.carlroth.com/jsp/en-com/sdpdf/9461e.PDF&sa=U&...
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