SupaVillain
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Arsenic Safety
How do I clean arsenic off of my equipment? Should I just keep everything totally contained in a container and throw it away? (Except for opening it
to retrieve the substrate)
I'm looking to use one of the following arsenic sources for MOVPE (metalorganic vapor phase epitaxy)
Arsine AsH3, Gas
Tertiarybutyl arsine (TBAs), Liquid
Monoethyl arsine (MEAs), Liquid
Trimethyl arsine (TMAs), Liquid
....but im afraid of arsenic contamination. It's really preferably a liquid that has nitrogen bubble through it to push vapors onto a solar panel,
after that the vapors are vacuumed out of the chamber. I'd really like to avoid contaminating my vacuum pump but that seems impossible. Among
phosphine and pyrophoric gases arsenic is the only one Im really worried about
Oh.
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SupaVillain
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By "throw it away" i mean either taking it to hazmat disposal or launching it over the castle wall in my trebuchet while orcs hold me under siege
nomsayin
Oh.
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SupaVillain
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apparently it can be cleaned with the amino acid cysteine. As for the MOVPE system there are scrubbers that have been designed for the dangerous gases
of phosphine, arsines, etc. I think I will have to use arsenic trioxide for synthesis of trimethylarsine, arsenic being the limiting reactant. It
doesn't seem simple to dispose of at all. Normal hazardous waste management doesn't seem to list it. Arsenic trioxide is far more toxic than
trichloride and most other kinds, but the end result trimethylarsine is far less toxic than arsine, being the most toxic, or so I've read.
Oh.
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j_sum1
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I have no experience on this (and no real desire to play with As compounds) so I can't offer much.
All I can say is that this topic is a great post/username combo. Mwaa ha ha ha!
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macckone
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Convert the arsenic using zinc and sulfuric acid then burn the gas onto something more disposable (marsh test). Or just clean the glassware outside
on a windy day. Aresenic compounds are readily reduced by hydrogen to the gas. Arsenic reputation as a poison is overrated. The main problems are
that arsenic is readily absorbed and cumulative. But it generally takes a gram or so to poison someone. It was often used in the past because it was
tasteless and undetectable. The marsh test is credited with ending it's use as poison as it greatly increased the sensitivity of existing test and
it's use was credible in court where prior test were not due to deterioration of the precipitate.
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SupaVillain
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Triphenylarsine!!!
I think I've cut out about 90% of the danger here.... instead of putting arsenic trioxide into trimethylaluminum to get trimethylarsine, I can just
buy triPHENYLarsine, which is cheap and common, also far less toxic than the trioxide. It's also fully ready for MOCVD so that cuts out an entire
synthesis step that involved pyrophoric TMA.
I think i will somehow open its container while it is in its main bubbler. LD50 is 146mg/kg of a rat or mouse, and that's about over 12 grams for me,
whereas I'd only be buying about 5 grams for 20 to 30 dollars before shipping.
The only catch is that it's less simplistic and easy to use a solid for MOCVD than a liquid, but the melting point is around 60 degrees C so I doubt
it'll be annoying and i'd much rather compensate design and complication for a far more dangerous method.
I found the idea of using triphenylarsine from this patent in the background art sections, it suggests some different precursors to use for certain
elements: https://www.google.com/patents/CA1251804A1?cl=en
Oh.
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Fluorite
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Is Arsenic REALLY toxic?
It was believed that with prolonged consumption of small doses of arsenic, the body develops immunity. This fact has been established for both humans
and animals. There are cases when habitual consumers of arsenic immediately took doses several times higher than the lethal dose and remained healthy.
Experiments on animals have shown the originality of this habit. It turned out that an animal accustomed to arsenic when consumed quickly dies if a
much smaller dose is injected into the blood or under the skin. However, this "addiction" is very limited, in relation to the so-called. "Acute
toxicity", and does not protect against neoplasms. However, the effect of microdoses of arsenic-containing drugs as an anti-cancer agent is currently
being investigated.
https://ru.m.wikipedia.org/wiki/Мышьяк
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