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careysub
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Radiochemistry
This may turn into a Donnybrook, but I want to open a reasoned, factual discussion of amateur radiochemistry - on the same level of other discussions
on this website.
This site has many discussions of handling dangerous materials - such as the long running thread on the preparation of gram-scale amounts of phosphorus
(mostly by processes that distill vapor), for a material that causes severe poisoning in amounts of 15 mg, and with a lethal dose of 50 mg.
Other popular threads include discussions of shaped charges, in fact there is an entire forum devoted to preparing high explosives (Energetic Materials).
Although special, unusual hazards are called out on occasion when an ill-advised preparation procedure is described, notable absent are comments that
seek to shut down the entire discussion.
With the mention of radioactivity on the other hand, then such comments pop up with some regularity. [I can cite examples if others insist.]
I am interested in at least discussing, if not performing, replication of some of the key processes of the early nuclear era: isolation of the more
stable daughter nuclides from uranium ore, the separation of americium and preparation for display, etc.
Due the availablity of materials, if for no other reason, these types of experiments are limited to working with microcurie amounts - amounts where
the hazards of exposure are confined to the hazards of actual ingestion.
Under the NRC General License for the use of nuclear materials quantities of not more than 5 microcuries are generally exempted from filing for a
specific license, i.e. are normally legal to possess. The only substantial hazard from sources of this magnitude is ingestion.
For example the skin dose for 1 microcurie of Ra-226 (i.e if you applied it to your skin, not recommended, and easily avoidable) is 20 mRem an hour.
You would have to leave it on your skin for 40 hours to raise an average annual exposure to radiation (350 mRem) to the average annual exposure that
people living in Denver receive every year (1200 mRem), and that is only in the region of the skin affected.
For Am-241 the skin dose is only 1 mRem, and if it were in a test tube the exposure would be near zero (low energy gammas are too weak to penetrate).
I submit we should be able to discuss microcurie level experiments without evoking cries of great alarm.
Discussion of actual safety precautions is desired and indeed, welcomed.
[Edited on 7-8-2014 by careysub]
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careysub
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To start off any discussion that may follow, it is obviously necessary to have some way of detecting radiation to follow what is happening with any
manipulation since you cannot see the material.
Designs for a variety of simple and inexpensive ionization detectors are readily available, one that in particular looks well suited is the "polonium
pen" described here:
http://www.techlib.com/science/ion.html
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Brain&Force
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Quote: Originally posted by careysub  | | For Am-241 the skin dose is only 1 mRem, and if it were in a test tube the exposure would be zero (gammas are too weak to penetrate).
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You need lead sheets to stop gamma rays. Test tubes won't cut it.
I would be interested, but what kind of projects do you have in mind (specifically, with what elements/sources?)
At the end of the day, simulating atoms doesn't beat working with the real things...
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Texium
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Perhaps he meant alphas? Am-241 is an alpha emitter after all, that would have made a lot more sense.
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careysub
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Lets see if I "misestimated" from taking a quick look at penetration energy graph.
Am-241 produces gammas of three energies 14, 16 and 60 keV. The mass attentuation coefficient for borosilicate at these energies are ~5.2 cm^2/g for
the first two, and 0.24 cm^2/g for the third. You can get thick-walled test tubes with a 2 mm wall, and the density is 2.2, for a mass-thickness of
0.44. I calculate that 90% of the lower energy gamma flux would be blocked, but only 10% of the most energetic. A roughly similar amount (~10%) of the
higher energy would be blocked by the layer of fluid, if the material is in solution.
So 80% or so of the 60 keV gammas (produced by only about 1/3 of the decays) would escape the tube wall.
So you are right, only partial protection (but more than you thought I expect). It represents only about 0.3% of the total decay energy.
But lead is not required, 1/8" of stainless steel would block 95% of the escaping 60 keV gammas.
http://physics.nist.gov/PhysRefData/XrayMassCoef/ComTab/pyre...
| Quote: | | I would be interested, but what kind of projects do you have in mind (specifically, with what elements/sources?) |
Replicating the separation of radium from pitchblende, performed by Mme. Curie for example.
Replicating the separation of a transuranic (americium) from uranium and other elements by the bismuth phosphate process used by the Manhattan
project.
Preparing a phosphor/americium or a phosphor/radium mixture for display.
[Edited on 7-8-2014 by careysub]
[Edited on 7-8-2014 by careysub]
[Edited on 7-8-2014 by careysub]
[Edited on 7-8-2014 by careysub]
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vmelkon
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I don't see why you can't discuss it.
Have you done any of these experiments?
Do you want to discuss actual experiments or talk about possible experiments.
Personally, I have only done Am-241 + Al foil.
Signature ==== Is this my youtube page? https://www.youtube.com/watch?v=tA5PYtul5aU
We must attach the electrodes of knowledge to the nipples of ignorance and give a few good jolts.
Yes my evolutionary friends. We are all homos here. |
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IrC
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I have no doubt on many sites this hyper hysteria is what you are used to encountering. However here I think you will find many who are very
interested in the science, myself being one of them.
I submit you should begin by posting a working plan on solvent extraction of Uranium from it's ores. Mostly because I am tired of waiting for United
Nuclear to actually write the page on it they have promised to do for many years yet have not.
I suspect you are Carey Sublette, and have forgotten more on the subject than most will ever know. I read your pages "Nuclear Weapons Frequently Asked
Questions" many years ago. Very good read.
http://nuclearweaponarchive.org/Nwfaq/Nwfaq.zip
Nice to have someone here very well versed on the subject. We have a few threads on building detection devices also. You will find people here are
more into the science of things and less into the hysteria so prevalent most places online.
By the way Carey welcome to SCM. You are no doubt one of the most knowledgeable people on the subject of nuclear energy ever to post on this site (if
not indeed the most knowledgeable) . I hope you stay for a long time. Someone with your knowledge is a great benefit to this site.
"Science is the belief in the ignorance of the experts" Richard Feynman
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neptunium
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when the litterature mentioned "on contact with the skin" they dont think you are actually going to put a source of radium or Americium in your pocket
and walk arround with it for a day or two...
they mean the dust that we cannot see the radioactive powder generated by the chemical treatment of radio active element in chemical reactions. the
short lengh particle like alpha and beta (or low energy gamma)
become a real threat to the health if not removed from the skin or the inside of the human body,
having said that, the fear of contamination and death by exposure when it comes to milicurie is vastly exagerated and simple common sense and
protection eliminate most of the risk.
it is in fact less dangerous to react 5milicu of Am241 than 5 ml of PCl3 ! i think we will all agree to that!
even with large amount of uranium ore , the danger of exposure to lethal radiation is often exagerated .
we are always reminded of Marie Curie brutal fate ,lets not forget that after years of manipulations of enormous amount of Radium it still took over
a decade to develope leucemia. and no one knew what to look for at the time!
again common sense and normal laboratory safety habit inhibit most of the risk when it comes to radiological hazard or not.
in conclusion, as for explosives/toxic chemicals i would sudjest the same approach....
do the research ( know the danger)
low quantities and
always wear safety gears
that kept me out of trouble so far...
now what do you want to do ?
the chemistry of radio isotope ( in particular trans uranium group) is fascinating and very well deserve a chapter in this site !
[Edited on 8-8-2014 by neptunium]
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Texium
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| Quote: Originally posted by neptunium |
the chemistry of radio isotope ( in particular trans uranium group) is fascinating and very well deserve a chapter in this site !
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Indeed it does... maybe even its own subforum if it really takes off.
I'd love to do some (careful) dabbling with radioactive experiments. I wanted to buy a cheap ionization smoke detector at the hardware store the other
day to dissect, but my dad wouldn't let me because he thought it was a "waste of a perfectly good smoke detector"  which surprised me because normally he lets me buy whatever I want for my experiments.
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neptunium
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hhaa yeah i remember those fustrating days of not being able to afford much and dreaming about having my own lab....
patience my friend! we all get old to soon...
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Marvin
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I am a fan of the nuclear weapons archive. That aside I remember a biological description of radiation from a tv program about 20 years ago Gammas
were likened to air pellets, sailing through matter and scattering without a lot of damage. I don't remember what betas were likened to but alpha
particles were bowling balls, they'd knock everything over if they could get through the dead layer of the skin. Inhalation or ingestion removes this
block and the alphas blast everything to bits with their high specific ionisation. Uranium ore is of the order 1uCi per gram of uranium, but that
comes with up to the same amount of polonium, the same amount of long half life radium and all the daughters in between and down to lead in
essentially invisible amounts.
If you use a Geiger counter to follow the chemistry you can be fooled. Boiling a uranium salt in slightly alkaline solution (a transition metal
co-precipitant helps) produces a highly active precipitate and a 'dead' solution. The ppt is actually short half life thorium and the solution
regains it's activity over days/weeks.
All wet chemistry contaminates every surface around it and is absorbed to some extent by the chemist. Most nasties discussed in this forum are
rendered safe by natural processes in human acceptable time-scales, phosphorus, cyanide, even metallic mercury is excreted by the body pretty well
given a non-contaminated environment. Radium is quickly laid down in bones and stays their for life (it's or yours) with all it's daughters as an
alpha emitter.
I know I have a tendency to be preachy and patronising but I think a lot of the members of this forum are young and high spirited and would happily
try things that could seriously affect their life span. SM has had at least 1 death and RS has had at least two. The radioactive boy scout did
end up with radiation poisoning and I think doing radiochemistry at home is like a child stirring dog shit with a stick.
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neptunium
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Marvin is right , we have to consider the youngest home scientist reading these posts.
I have a degree in physics and decontamination in nuclear power plant where i worked in a lab for school 15 years ago. and although i would love to do
some radiochemistry at home i am not willing to contaminate
my family or anyone else`s.
the danger cannot and should not be underestimated although low the consequences of a small mistake could be dire.
things always happen in the lab sometimes benine sometimes bad . dealing with the clean up is one thing, dealing with a doctor telling you about your
rare cancer is another
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IrC
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So I guess the first thought careysub had was right.
"Marvin is right , we have to consider the youngest home scientist reading these posts."
I agree first off close down the energetics forum and lock it from all access since I have no doubt far more young and upcoming scientists have been
harmed dabbling with explosives by orders of magnitude than radio-chemistry.
"dealing with a doctor telling you about your rare cancer is another"
I never noticed every thread in Organics being given this warning even though I have no doubt statistically cancers have been caused by exposure to
chemicals in greater numbers than radiation. We all know many if not most organic solvents are carcinogenic.
Why is it the two of you are not busy posting warnings to stay away in all other sub forums on this site? I implore you to show the statistics on harm
caused by this topic as compared with all other topics in amateur science.
"Science is the belief in the ignorance of the experts" Richard Feynman
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neptunium
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the point was to not encourage younger maybe foolish readers.
the science is always good and i strongly beleive in self responsabilities
and consequences . god knows i did my share of foolish experiments! we all did..
Also firm beleiver in free expression so no need to shut down energetics and radio chemistry.
However , i am reluctant encouraging spoon feeding and detailled procedures to inexperienced
beginers or bored sunday teens.
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careysub
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I had been working on this position paper on radiophobia for a couple of days, and I think that it is good to post it to provide a safety context:
On Chemophobia and Radiophobia
The ScienceMadness Wikia has an article entitled "Chemophobia", which begins: "Chemophobia is an irrational fear of chemicals, particularly synthetic
chemical...".
What does it mean for a fear to be irrational? What objective test will distinguish between one such, and a rational fear? Or is it all a matter of
subjective name-calling?
There is an objective way of determining whether a risk is being perceived in an irrational way: if it is being accorded a level of concern that is
inconsistent with the viewers other views about risks of similar magnitudes. If risks that are measurably larger are being accepted with equanimity,
while substantially smaller ones are regarded with alarm, then this is a "phobic" attitude.
One cannot live life without taking risks. Even making a quick trip to a nearby store exposes one to the possibility of death in a traffic accident.
Currently the risk of death in the U.S. per mile travelled in a car is about one fatality per 50 million miles travelled. A five mile round trip to
the store then amounts to accepting a 1-in-ten million risk of traffic death in exchange for the convenience of buying what ever it is you wanted to
buy. Very few people give this a first thought, much less a second.
When dealing with fatal hazards it is also important to consider the concept of "number of years of life lost". A fatal traffic accident will kill you
today, and the remaining years of your life will be lost. If you are 30, we might estimate this loss at 50 years. On the other hand the risk of
exposure to a weak chemical carcinogen might exposure you a risk of death from the exposure of 1-in-ten million (like the 5 mile car trip), but that
death would occur decades later so the loss of life-years would be greatly reduced.
With chemophobia fear is largely driven by sheer misinformation - believing risks are far larger than they really are, often any risks are
immeasurably small if they exist at all.
A parallel phenomenon exists with regards to radiation, which affects a fair number of the ScienceMadness community. In this case potentially severe
hazards from handling chemicals are often taken in stride, while risks from very low-level radiation exposure that are immeasurably small give calls
of alarm.
The accepted point of view on this forum with regards to chemical safety is that experiments in general can be conducted "safely" (with a small chance
of adverse result to the individual) if proper procedures are followed. Not infrequently there is discussion of proper safety procedures, and
sometimes a proposed experiment is nixed as being excessively dangerous without extraordinary precautions, but generally experiments are discussed
without explicit reference to safety procedures, because otherwise all discussions would be vastly expanded with the same sort of boilerplate warnings
that occupy the first ten pages of every product manual these days.
In the 13 page long lead salts preparation thread there is only one poster referring to the severe chronic lead toxicity problem. OSHA recommends a
lead body burden limit of only 400 micrograms per kg, or 28 mg in a 70 kg adult. Many of the experiments discussed on the thread were processing
amounts tens of thousands of times larger than that, so that an accidental absorption of only 0.01% of the material being handled would expose you at
a level regarded as unsafe.
By contrast discussions about handling radioactive materials with permissible levels of radiation, levels low enough that the NRC feels that they do
not need any sort of license to possess or handle, often evoke cries of generalized alarm.
As a specific example, in a recent thread I mentioned that it was possible to make a striking glowing display specimen of americium for an element
collection by dissolving it (0.9 microcuries) from its gold smoke detector carrier (requiring aqua regia), and deposit on zinc sulfide for enclosure
in a sealed tube for display.
Whereupon another poster, ignoring the hazard of the aqua regia, declared it irresponsible to suggest that such a thing could be done.
But consider the contrast in risks.
What is the worst thing that could happen if aqua regia is mishandled? It could cause agonizing burns, permanent disfigurement and blindness, and if
you were so daft as to swallow it, a fatal result from internal injury could not be excluded.
What is the worst thing that could happen if 0.9 microcuries of Am-241 is mishandled?
The worst case would be to swallow it all. And what then?
First off the exposure would within OSHA limits of acceptable workplace exposure if averaged over a period of 15 months, so it would not be out of
line with accepted workplace safety standards.
Second, it would impossible to detect any adverse affect on the individual from the ingestion, ever. The amount ingested is less than the amount of
natural radioactive potassium in your body (1.2 microcuries). The only hazard from the exposure would be to increase the lifetime cancer risk of the
individual from about 30% (the chance everyone takes), by an incremental amount of 0.03% to 30.03% if factored over a 50 year period (older people
would have less risk exposure). If one eventually did get cancer, there is only a one in one thousand chance that swallowing the americium was
responsible.
But the same lab safety procedures than keep you from swallowing lead, or the aqua regia, will be just as effective in keeping you from swallowing
americium. If we felt that is was achievable to limit lead intake to less than 0.01% of the material you were handling in the lab, then those
procedures would do the same with the heavy metal americium, limiting actual exposure to something like 0.09 nanocuries (3.7 Bequerel), or less than
1/10 of the radiation in a 1/4 tsp serving of Nu Salt salt substitute.
[Edited on 10-8-2014 by careysub]
[Edited on 10-8-2014 by careysub]
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careysub
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| Quote: Originally posted by Marvin | ... Inhalation or ingestion removes this block and the alphas blast everything to bits with their high specific ionisation....
If you use a Geiger counter to follow the chemistry you can be fooled. Boiling a uranium salt in slightly alkaline solution (a transition metal
co-precipitant helps) produces a highly active precipitate and a 'dead' solution. The ppt is actually short half life thorium and the solution
regains it's activity over days/weeks. |
Depends on what you mean by "fooled".
The counter is giving you an accurate assessment of the radiation present. If you know your nuclear chemistry there is nothing "fooling" going on -
freshly separated natural uranium will reach equilibrium with the 24 day Th-234 and Pa-234 (1.5 minutes) and its net by 150% radioactivity, to match
any other "old" sample of separated uranium. Meanwhile that active precipitate will decay way over several months.
| Quote: | | All wet chemistry contaminates every surface around it and is absorbed to some extent by the chemist. |
What fraction of the chemicals you handle normally get absorbed into your body would you estimate?
One advantage of radioactive materials is that surface contamination is very easy to detect. Not so chemical poisons.
| Quote: | | Most nasties discussed in this forum are rendered safe by natural processes in human acceptable time-scales, phosphorus, cyanide, even metallic
mercury is excreted by the body pretty well given a non-contaminated environment. |
Metallic mercury (as in mercury vapor) passes easily through the blood-brain barrier, and the estimated retention time there is 25 years.
Lead? Not excreted - it accumulates. The permissible body burden is only 24 mg.
Maybe we shouldn't discuss handling mercury or lead in our forums?
| Quote: | | Radium is quickly laid down in bones and stays their for life (it's or yours) with all it's daughters as an alpha emitter. |
True. You don't want to absorb it, just like you don't want to absorb metallic mercury or lead. Appropriate safety precautions should be taken.
But if you are working with the amount permitted without license by the NRC, 5 microcuries, and successfully avoid absorbing more than a tiny portion
(which I believe would be typical for properly conducted set of chemical operations), then you are talking about very small life-time risks.
| Quote: | | I know I have a tendency to be preachy and patronising but I think a lot of the members of this forum are young and high spirited and would happily
try things that could seriously affect their life span. |
It is impossible for any amount of radioactive material complying with the NRC general license to do this, no matter how it was mishandled. The worst
case for the maximum amount would be something like a 1-in-1000 chance of contracting cancer late in life.
| Quote: | | SM has had at least 1 death and RS has had at least two. |
I would guess from energetic materials, which are discussed quite extensively and freely here, yes?
Are you calling for a shut-down of that forum?
| Quote: | | The radioactive boy scout did end up with radiation poisoning |
No, David Hahn has never shown any adverse symptoms from his radiation exposure. Nor is it expected that he ever will.
| Quote: | | and I think doing radiochemistry at home is like a child stirring dog shit with a stick. |
An odd comparison. I have never known any harm to come from that activity.
[Edited on 10-8-2014 by careysub]
[Edited on 10-8-2014 by careysub]
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careysub
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| Quote: Originally posted by vmelkon |
I don't see why you can't discuss it.
Have you done any of these experiments?
Do you want to discuss actual experiments or talk about possible experiments.
Personally, I have only done Am-241 + Al foil. |
No, haven't done any of these experiments yet.
I am considering plans for doing some over the next few years, and I intend to discuss those plans to solicit comment in advance of actually carrying
them out.
Discussing safety procedures, and safe quantities, are an important topic to be covered.
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careysub
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| Quote: Originally posted by zts16 | | Quote: Originally posted by neptunium |
the chemistry of radio isotope ( in particular trans uranium group) is fascinating and very well deserve a chapter in this site !
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Indeed it does... maybe even its own subforum if it really takes off.
I'd love to do some (careful) dabbling with radioactive experiments. I wanted to buy a cheap ionization smoke detector at the hardware store the other
day to dissect, but my dad wouldn't let me because he thought it was a "waste of a perfectly good smoke detector" which surprised me because normally he lets me buy whatever I want for my experiments. |
The first thing you should do is make a radiation detector in advance of trying anything else with radiation.
Detecting radiation with a cloud chamber is really cool (especially since it uses dry ice).
A smoke detector source is way too strong for this, a cloud chamber source needs to be about 0.01 microcuries not 1.0 microcuries (it would just make
the chamber a "fog chamber").
You can do a safe radiation demo if you get a smoke detector source and a zinc sulfide coated scintillation screen like this one:
http://www.ebay.com/itm/ZnS-Ag-scintillation-screen-spinthar...
You can also make a gold-foil electroscope and show how a smoke detector source makes it lose its charge immediately. A sample of uranium ore works
well too.
Making a spinthariscope is pretty neat also.
Then consider getting a Geiger counter kit (there are several available), or making an ionization chamber detector.
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careysub
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Radiophobia and Chemophobia
The high alarum some have raised at the very mention of manipulating radioactive materials however small the amount represents an extreme
inconsistency in how they themselves ordinarily evaluate risk, even in the case of radioactivity (more on this below).
Recall that the quantity of radiation currently under discussion is at the level of several microcuries or less, amounts typically permitted under the
NRC general license without registration. At these levels even gross mishandling of the material (the worst case is ingesting all of it in soluble
form) is swamped by ordinary daily exposures. The resulting radiation exposure hazard from ingesting the one microcurie of Am-241 in one smoke
detector is 15 millirem a year, similar in risk to an extra 375 millirem all at once if you are 25 or so (similar to a lower one if you are older).
For comparison the exposure from natural radioisotopes found in everyone's body (K-40, C-14) is 40 millirem a year. Flying three coast-to-coast round
trips a year exposes one to 15 millirem. The average total annual exposure from natural sources is about 350 millirems, and the variation in
background radiation in different parts of the U.S. varies from a low of 250 millirems to a high of 1500 millirems. A 15 millirem additional annual
exposure amounts to about 1% of the extra hazard of living in parts of New England or Colorado.
How many people out there regularly (or ever) consult a map like this one of the US background radiation field?
http://www.goldismoney2.com/attachment.php?attachmentid=7223...
Travelling from a low radiation area to a high radiation area constitutes an added exposure as large as 100 millirems a month. If you are from Florida
and spend four months in some parts of Colorado your added cancer risk from that trip is as large as "eating the smoke detector". Where are the stern
admonitions about the peril of visiting the Rocky Mountain State?
If you don't care about small incremental radiation exposures at any other time in your life, why is it now so alarming that the mere discussion of
it in the context of chemistry is considered intolerable?
Consider the practice of ordinary chemistry. There are many terribly dangerous activties involved, that can easily cause injury, severe property
destruction, or even death. Activities like using fire.
Seriously - has anyone here ever thought that the use of an alcohol lamp or other burner, even by a young person epxerimenting with chemistry, is an
intolerable hazard?
In one year in the U.S. there are nearly half a million house fires that require fire department attention, kill 2500 people, injur some 15,000
(severely enough to be reported). I will bet that a large portion of the readers here have at least one burn scar, however small, somewhere on their
body. This represents a real, and painful, physical injury that is disfiguring, if only slightly.
Use of an exposed flame in an environment where flammable chemicals are present is an extreme potential hazard. But I submit, the attitude toward this
risk is: follow appropriate safety procedures, don't do something stupid, and you will be fine. No problem. But the worst case potential accident is
often dire indeed.
Consider the hazard represented by the chemicals typically used in experiments.
The worst case scenario with microcurie amounts of radioactive substances is the extreme one of consuming all of the sample. And the most apocalyptic
result is a very small theoretical ("theoretical" since it is projected from theory and can never be detected in practice) cancer risk increase
decades in the future.
Let us use this same standard for risk-assessment with most any of the experiments described on this site - how many of the experiments here would
produce no detectable adverse effect if you ate all of the reactants? A large share of them would kill you outright. This represents a risk factor
something like four orders of magnitude greater, yet such potential risks normally pass here without any comment. Again proper procedure protects
against accident it is believed, and no one is upset.
And consider this: chemistry allows you to make highly toxic substances when before you have none. A 16 year old who frequented this site apparently
died because he made phosgene and poisoned himself a few years ago.
Radiochemistry is restricted to the quantity of radionuclides you start with. You cannot make more (only nuclear physics can do that), and NRC
regulations and the sheer cost make it all but impossible to obtain genuinely hazardous amounts.
If microcurie chemical manipulations are deemed too hazardous to discuss on this site, I submit that consistent behavior would require complete
shut-down of the entire site, not just the "explosives group". Chemistry could hurt someone! Think of the children! Better to forbid it be discussed!
The opposition to responsible radiochemical investigation is radiophobia, the precise parallel of chemophobia, and every bit as extreme in
mischaracterizing the risks. This is "Science Madness", not "Reefer Madness".
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careysub
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Microchemistry
One attractive feature of pursuing amateur radiochemistry is the boost it gives to a very interesting area of chemical technique: microchemistry. I
understand this sort of a cutting edge thing - being adopted by universities around the world to improve the quality of chemical education (you can
contemplate more elaborate procedures with tiny amounts), and reduce costs, and environmental impact.
Here is a an article detailing this state-of-the-art field of chemistry:
http://actinide.lbl.gov/gtsc/seminars/2012/PuLab_LifeInterna...
Yes, it is a 1946 Life magazine article detailing the advances in microchemistry created by the Manhattan Project. This technique was well established
70 years ago! Unfortunately those nifty little necked "microcones" used by Seaborg and company do not seem to be made anymore. Cone-shaped microwell
plates seem to be what people use.
(Microchemistry actually dates from the century before - it was founded by Francois-Vincent Raspail in the 1830s).
Handling chemicals present in microgram amounts calls for equipment scaled down by a factor of 1000 from what you might use when treating milligrams
or grams. A "large" flask is not 1000 mL, but 1 mL and so on. Tiny amounts of solvents and other reagents are used. This has the advantage of making
very expensive reagents, or ones that can ony be made in low yield, practical.
More exotic lab conditions can be obtained more easily:
Want to use a hyper-corrosive solution? Pressing a bit of platinum foil into a conical microwell cavity will give you a platinum reaction chamber.
Want to test a reaction at a very high temperature? A sample can be set-up for heating in an oxyhydrogen torch, or an arc furnace on a benchtop.
If you are interested in the chemistry itself, instead of performing production processes (nothing wrong with that - not a thing), then microchemistry
has many attractions and advantages.
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MrHomeScientist
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| Quote: Originally posted by careysub | | If you are from Florida and spend four months in some parts of Colorado your added cancer risk from that trip is as large as "eating the smoke
detector". |
That's exactly my situation! Except I'll only be visiting for a week, so my risk would be 1/16 of a smoke detector 
| Quote: | | One attractive feature of pursuing amateur radiochemistry is the boost it gives to a very interesting area of chemical technique: microchemistry.
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I'm not a big fan of microchemistry for the amateur chemist, personally. The amounts discussed are so miniscule that you really have no idea what
you're working with without fancy equipment to detect your products. Plus I think a lot of amateurs (myself included, probably) don't have the skill
or equipment necessary to manipulate such tiny amounts. When your entire stock of a chemical is contained in a single drop, a shaky hand could ruin
the whole experiment. And what of that last bit of solution that stays in the pipette? I guess my point is that any losses are magnified extremely in
microchemistry - 0.01mL adhered to a beaker means nothing when working with liters, but is significant when you only have microliters. Finally, when
your experiment is done you have a barely visible product, which to me doesn't seem worth the effort. Perhaps I have "microphobia," though.
More on topic with radiochemistry, I definitely see what you mean. Even I am quite wary of radioactive substances - too much so, it seems. Your
reasoned arguments have really given me pause and made me think more about how I assess risk. I too have been waiting for forever for United Nuclear
to post Part 2 of their uranium extraction. It would be great to see some work in this area here on the board.
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Texium
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| Quote: Originally posted by MrHomeScientist | | Quote: | | One attractive feature of pursuing amateur radiochemistry is the boost it gives to a very interesting area of chemical technique: microchemistry.
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I'm not a big fan of microchemistry for the amateur chemist, personally. The amounts discussed are so
miniscule that you really have no idea what you're working with without fancy equipment to detect your products. Plus I think a lot of amateurs
(myself included, probably) don't have the skill or equipment necessary to manipulate such tiny amounts. When your entire stock of a chemical is
contained in a single drop, a shaky hand could ruin the whole experiment. And what of that last bit of solution that stays in the pipette? I guess my
point is that any losses are magnified extremely in microchemistry - 0.01mL adhered to a beaker means nothing when working with liters, but is
significant when you only have microliters. Finally, when your experiment is done you have a barely visible product, which to me doesn't seem worth
the effort. Perhaps I have "microphobia," though. |
I agree with you about that. I've tried doing really small
scale experiments before (not even true micro) and it got very confusing ("I think it reacted...?"). In the end, I got what I thought was a good
product, but I had so little of it that if I tested to ensure its purity (or at least its identity), I would have lost most of it, and then I wouldn't
have it anymore after working so hard for it. I'm all for macro scale experiments, test tube scale at least. Last night I read through this thread that was a debate about microscale vs macroscale and their place in both professional labs and amateur labs.
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careysub
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| Quote: Originally posted by MrHomeScientist |
...
I'm not a big fan of microchemistry for the amateur chemist, personally. The amounts discussed are so miniscule that you really have no idea what
you're working with without fancy equipment to detect your products. Plus I think a lot of amateurs (myself included, probably) don't have the skill
or equipment necessary to manipulate such tiny amounts. When your entire stock of a chemical is contained in a single drop, a shaky hand could ruin
the whole experiment. And what of that last bit of solution that stays in the pipette? I guess my point is that any losses are magnified extremely in
microchemistry - 0.01mL adhered to a beaker means nothing when working with liters, but is significant when you only have microliters. Finally, when
your experiment is done you have a barely visible product, which to me doesn't seem worth the effort. Perhaps I have "microphobia," though.
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Thanks!
Perhaps we could declare a middle ground: "mini chemistry"?
The fact is, with practical radiochemistry you are working with a radioactive tracer - something that can only be detected by its radiation emissions
and while you could dissolve it in a liter, a milliliter would do as well.
The only way you can work with bulk, macroscopic material is to work with natural radionuclides of ancient cosmic origin (uranium*, thorium*, and
potassium) or to have your radionuclide embedded in a carrier (as with radium and barium).
Reasonably priced scales with a sensitivity down to one milligram are readily available, beakers and test tubes with volumes of 2-3 mL. Although it
seems hard to find a flask less than 10 mL I'm not sure there is need on any. Volume measuring precision is limited to about 100 microliters (using a
graduated syringe) or 40 (maybe 25?) microliters using a calibrated dropper, but you can weigh solutions with 1 microliter accuracy. Working with
masses on the order of 10-100 mg, and fluid volumes of 0.1 to 1 mL seems to allow acceptable precision with readily available equipment. Certainly it
is small scale if not what is considered true "micro".
Even here you're raw materials are running $10/g and up.
[Edited on 13-8-2014 by careysub]
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careysub
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| Quote: Originally posted by MrHomeScientist |
I too have been waiting for forever for United Nuclear to post Part 2 of their uranium extraction. It would be great to see some work in this area
here on the board. |
You must be referring to this page (which I had not seen until now):
http://www.unitednuclear.com/extract.htm
Since he is selling uranium ore for around $3/g (as best I can determine) the 300 g he starts with in the demo would cost around $1000 if bought from
him.
The best deal I know of on uranium is ore is 1 kg of German pitchblende for $175 from Shannon and Sons.
I can start working on a process flow chart, but it will be theoretical for a good while, and my focus is on extracting and separating all of the
radionuclides to the extent that is possible, not just extracting the uranium.
I'll be publishing a series of essays over time (see, I've already started), the initial focus will be on detectors and calibration sources without
which nothing much can be done (except maybe extracting uranium).
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MrHomeScientist
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That's good stuff, carysub. The page you linked is indeed what we were talking about. He does occasionally get in 'bulk' uranium ore,
or larger pieces of high activity ore, but is frequently sold out. I imagine that would be cheaper per gram, but your point is well taken.
I think "mini chemistry" is certainly acceptable, especially when dealing with expensive reagents. In fact pretty soon I'm going to try my hand at
purifying natural placer gold via aqua regia, which necessarily will be with under 1g of gold as a starting material. That's pretty mini, and I didn't
really even think about that until just now!
Something else I'd love to see, to know if it's practical, is to reduce the AmO2 found in smoke detector sources to elemental Am. I'm using one such
pellet as my sample for my element collection, but it would be much better as the element rather than a compound
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