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unionised
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Quote: Originally posted by Morgan  |
I can't think of any simple getters for oxygen the way limewater works for CO2.
[Edited on 21-10-2018 by Morgan] |
The traditional ones are alkaline solutions of pyrogallol or chromous chloride, or powdered iron or copper in the presence of ammonia and ammonium
chloride solution.
From a home chemist perspective...
https://en.wikipedia.org/wiki/Hand_warmer#Air_activated_(iron)
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Morgan
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There was this cobalt compound said to be able to absorb all the O2 out of a room from phys.org. I suppose the spoonful is actually put over a large
surface area like the way platinum is used on carbon or alumina?
"The material is so effective at binding oxygen, that only a spoon of it is enough to suck up all the oxygen in a room."
Read more at: https://phys.org/news/2014-09-material-oxygen-air.html#jCp
Another slant ..
https://motherboard.vice.com/en_us/article/8qxvna/this-new-o...
[Edited on 22-10-2018 by Morgan]
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wg48
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That’s BS you can not squeeze the oxygen from a room of air in to the volume of a spoon full of anything as its density would be greater than any
known material excluding neutron star material and black holes and assumes regular table spoons and typical room sizes.
Borosilicate glass:
Good temperature resistance and good thermal shock resistance but finite.
For normal, standard service typically 200-230°C, for short-term (minutes) service max 400°C
Maximum thermal shock resistance is 160°C
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Morgan
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| Quote: Originally posted by wg48 |
That’s BS you can not squeeze the oxygen from a room of air in to the volume of a spoon full of anything as its density would be greater than any
known material excluding neutron star material and black holes and assumes regular table spoons and typical room sizes.
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Your reaction was about the same as mine but I wondered how phys.org could be posting the nonsense. There were about a dozen articles that had the
same basic wording including Popular Science. They all ran with the same spoonful story. But then I thought maybe there was some possible way to
transfer O2 to a bulk quasi -zeolite type substrate with a coating of the active ingredient, thinking perhaps that's what they meant. Anyway phys.org
has shown itself on this occasion to be a fizz.org.
From the bottom of the page from the second link I posted ...quite a calculation error all around.
"Update 10/1: We've updated this post to correct a calculation error on the part of the researchers that suggested the oxygen-absorbing compound is
far more efficient than it actually is. In an emailed statement, a representative for Syddansk University said "I am just updating our story on our
website, because it turns out that Prf McKenzie made a calculation error. Pls note that it is not a SPOONFUL of this stuff, that we need to rid a room
of oxygen. It is a bucket (10 litres). We apologize." Motherboard apologizes for any confusion."
https://motherboard.vice.com/en_us/article/8qxvna/this-new-o...
[Edited on 22-10-2018 by Morgan]
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unionised
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Would anyone like to do the arithmetic on a bucket of coal or magnesium turnings?
I suspect that stuff is nothing special in terms of O2 trapping.
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wg48
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| Quote: Originally posted by Morgan | | Quote: Originally posted by wg48 |
That’s BS you can not squeeze the oxygen from a room of air in to the volume of a spoon full of anything as its density would be greater than any
known material excluding neutron star material and black holes and assumes regular table spoons and typical room sizes.
|
Your reaction was about the same as mine but I wondered how phys.org could be posting the nonsense. There were about a dozen articles that had the
same basic wording including Popular Science. They all ran with the same spoonful story. But then I thought maybe there was some possible way to
transfer O2 to a bulk quasi -zeolite type substrate with a coating of the active ingredient, thinking perhaps that's what they meant. Anyway phys.org
has shown itself on this occasion to be a fizz.org.
From the bottom of the page from the second link I posted ...quite a calculation error all around.
"Update 10/1: We've updated this post to correct a calculation error on the part of the researchers that suggested the oxygen-absorbing compound is
far more efficient than it actually is. In an emailed statement, a representative for Syddansk University said "I am just updating our story on our
website, because it turns out that Prf McKenzie made a calculation error. Pls note that it is not a SPOONFUL of this stuff, that we need to rid a room
of oxygen. It is a bucket (10 litres). We apologize." Motherboard apologizes for any confusion."
https://motherboard.vice.com/en_us/article/8qxvna/this-new-o...
[Edited on 22-10-2018 by Morgan] |
I was surprised no one had commented how ridiculous the statement was. My first mental guesstimate was a cubic foot of material would be required
(yes I still think in imperial units when i want a feel for the size of something). I assumed it was hype to increase the chance of more funding or
snagging gullible investors.
As a cross check: there is about .0.25kg of oxygen in a 1m^3 of air, if you assume 10l has the unrealistically high storage density of liquid oxygen
(approximately the density of water ) that’s 10kg of oxygen or 40 m^3 or a 3.4m cube of air.. A more realistic storage capacity is say 10% of
that of liquid oxygen making it a cube of 1.6m of air, ok a small room but close enough to be not immediately ridiculous.
Borosilicate glass:
Good temperature resistance and good thermal shock resistance but finite.
For normal, standard service typically 200-230°C, for short-term (minutes) service max 400°C
Maximum thermal shock resistance is 160°C
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macckone
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Let's run the numbers.
1 mole of activated iron will absorb 1.5 moles of oxygen.
So 56 grams will absorb 33.6L but oxygen is approximately 1/5 of air.
So that would be about 170L of air, of course we are only removing the oxygen portion.
A tablespoon would be 2 moles of iron or 340L of air.
BUT you only need to remove 10% of the oxygen in air to be dangerous.
so a tablespoon of activated iron would reduce oxygen enough to be dangerous in a 3.4m^3 room if spread carefully and totally sealed.
So not much more than a closet.
A 3 x 3M room with a 2.4M high ceiling (approx 10 x 10 x 8ft) would require 63 tablespoons.
about 3.6 kg of activated iron or about a half liter (density 7.87 - the granulating would make it lighter).
boron hydride is going to do better.
of course neither activated iron nor boron hydride is going to be reversable.
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wiglaf
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Thanks for the calculation. It's educational. FWIW, the iron would be far less dense than assumed (no way to get 2 moles of powdered iron in a
Tablespoon)
Except for the danger of having your closet implode from sudden depressurization, removing 10% of the oxygen is likely not "dangerous". Since you're
over a mile high, you already have 15-20% less oxygen than I do (lucky!).
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Tsjerk
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"Serious side effects can occur if the oxygen levels drop outside the safe zone. When oxygen concentrations drop from 19.5 to 16 percent, and you
engage in physical activity, your cells fail to receive the oxygen needed to function correctly. Mental functions become impaired and respiration
intermittent at oxygen concentrations that drop from 10 to 14 percent; at these levels with any amount of physical activity, the body becomes
exhausted. Humans won't survive with levels at 6 percent or lower."
source: https://sciencing.com/minimum-oxygen-concentration-human-bre...
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Morgan
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I remember some mention of oxygen when taking flying lessons, where flying at some particular elevation at night the instructor said taking a few
breaths of pure oxygen was like turning the rheostat up on the instrument panel, the brightness increased.
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macckone
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Where I am removing 10% of the oxygen would definitely be dangerous. Altitude sickness kills people all the time in the denver area, mostly via heart
attack. The worst locally is people flying in and then immediately driving up mt evans (14K feet) which has a pressure of 8.2psi (56% of normal -
equivalent to 12% oxygen). Altitude sickness actually takes a bit of time to kill you though. Where I am, it isn't that bad though. A mile high is
about 20% less, I have less oxygen than that.
And notice I said dangerous, not deadly.
The first effect of low oxygen is increased pulse. Next your body starts trying to remove liquid from your blood, reducing your blood volume. Then
your body releases blood cells from your spleen. Finally it starts producing more red blood cells. In some people the red blood cells are larger.
In others they actually significantly increase the red blood cell counts.
This can lead to heart attack or stroke if you have even slightly clogged arteries.
Altitude sickness itself can lead to pulmonary or cerebral edema.
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VSEPR_VOID
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| Quote: Originally posted by macckone | Let's run the numbers.
1 mole of activated iron will absorb 1.5 moles of oxygen.
So 56 grams will absorb 33.6L but oxygen is approximately 1/5 of air.
So that would be about 170L of air, of course we are only removing the oxygen portion.
A tablespoon would be 2 moles of iron or 340L of air.
BUT you only need to remove 10% of the oxygen in air to be dangerous.
so a tablespoon of activated iron would reduce oxygen enough to be dangerous in a 3.4m^3 room if spread carefully and totally sealed.
So not much more than a closet.
A 3 x 3M room with a 2.4M high ceiling (approx 10 x 10 x 8ft) would require 63 tablespoons.
about 3.6 kg of activated iron or about a half liter (density 7.87 - the granulating would make it lighter).
boron hydride is going to do better.
of course neither activated iron nor boron hydride is going to be reversable. |
There was an incident where one Marine armed with a flamethrower killed something like 50 Japanese infantry with one short burst. the reason why was
because he fired into the entrance of a cave, which cause a large amount of CO to drift down into the tunnel system. The result was CO poisoning of
all the infantry inside.
So a few liters of CO is better than a few Kg of activated iron for clearing rooms.
Within cells interlinked
Within cells interlinked
Within cells interlinked
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wiglaf
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I was referring to a 10% drop in oxygen levels (relative to starting) - NOT 10% oxygen! In other words going from 21% Oxygen to 19%. No doubt that
10% (absolute level vs 21% at standard) is dangerous. I was only trying to point out that a sudden absorption of 10% of the oxygen in the room would
be likely to lower the pressure enough to cause to the walls to buckle.
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wg48
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| Quote: Originally posted by macckone | Where I am removing 10% of the oxygen would definitely be dangerous. Altitude sickness kills people all the time in the denver area, mostly via heart
attack. The worst locally is people flying in and then immediately driving up mt evans (14K feet) which has a pressure of 8.2psi (56% of normal -
equivalent to 12% oxygen). Altitude sickness actually takes a bit of time to kill you though. Where I am, it isn't that bad though. A mile high is
about 20% less, I have less oxygen than that.
And notice I said dangerous, not deadly.
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If they arrived by jet airliner they have already been subject to about 33% less partial pressure of oxygen due to the reduced cabin pressure. Its
what can make your legs swell and ache on long flight not just lack of activity for so many hours.
Borosilicate glass:
Good temperature resistance and good thermal shock resistance but finite.
For normal, standard service typically 200-230°C, for short-term (minutes) service max 400°C
Maximum thermal shock resistance is 160°C
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Morgan
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From Cabin Pressurization topic in Wiki ...
"Scuba divers flying within the "no fly" period after a dive are at risk of decompression sickness because the accumulated nitrogen in their bodies
can form bubbles when exposed to reduced cabin pressure."
"The FAA’s Airman’s Information Manual (AIM) offers a small section entitled “Decompression Sickness After Scuba Diving” that indicates “a
pilot or passenger who intends to fly after scuba diving should allow the body sufficient time to rid itself of excess nitrogen absorbed during
diving. If not, decompression sickness due to evolved gas can occur during exposure to low altitude and create a serious in-flight emergency.”
https://www.tdisdi.com/scuba-diving-and-flying/
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macckone
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wg48:
Altitude sickness is actually made worse by the flight.
It isn't an instant reaction, it takes about 24 hours to develop.
But some people can have reactions that take longer.
The nederland police chief resigned in 2014 because he couldn't adjust to the altitude (8228 ft).
nederland is a crappy little mountain town as they are fond of saying in south park.
south park aka fairplay is actually at a higher altitude (10K ft).
Alma is also in park county and is the highest inhabited town in the united states at 10,578ft.
http://www.townofalma.com/
Morgan:
yes very dangerous. don't dive and fly.
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