HNO3
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Purification of Cerium Metal
I am trying to prepare 90%+ cerium metal for display purposes from Misch metal. I have reacted a rod of misch metal with 31.45% HCl(aq). the rod of
metal is estimated to be approximately 20-30% cerium over all. I now have light green crystals at the bottom of my beaker and a yellow suspension
above that. I now have decanted the liquid... Any pointers?
\"In the beginning, God...\" Wait a minute, God doesn\'t exist!!!!!!!!!! \"OK, in the beginning, ummm, hydrogen...\" Wait a minute, what about the
laws of thermodynamics? \"OK, in the beginning, ummm.....UMMMMM, what\'s left to choose from?
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neutrino
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It would be infinitely easier to just buy some cerium that to try to isolate it from misch metal. Misch metal contains other lanthanides, which will
be very difficult to separate. In fact, it took chemists many years to separate the lanthanides from one another because they (and their compounds)
all have essentially the same chemical properties. If you really want to try this, chromatography would be your best bet, although you will need a
very long column. Then, you’d need to get the chloride back into the metallic form, for which you’d probably need a thermite reaction, as it is
too electropositive for electrolysis.
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JohnWW
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It may be possible to chemically separate Ce from other rare-earth metals (excepting Th and U) using the fact that is the only one that can be
oxidized to a tetravalent oxidation state that is stable in a strongly acid solution, as e.g. Ce(NO3)4. (Pr, Nd and Tb can also be oxidized to
dioxides or tetrafluorides, but they decompose liberating oxygen when treated with aqueous acids). Otherwise, you would have to settle for
packed-column liquid chromatography of trivalent salts, in an acid solution, of the mixture of rare eath metals.
As for electrolysis back to the metal, this could be attained by doing it on a molten Ce(III) salt, most likely a halide.
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I am a fish
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Instead of wasting misch metal, why not start with cerium dioxide? It is readily available from telescope making suppliers, as an agent for polishing
home made telescope mirrors.
I imagine that extracting the cerium from CeO<sub>2</sub> would be difficult, but certainly no more so than extracting it from the impure
CeCl<sub>3</sub> that would results from dissolving misch metal in hydrochloric acid.
1f `/0u (4|\\| |234d 7|-|15, `/0u |234||`/ |\\|33d 70 937 0u7 /\\/\\0|23.
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JohnWW
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BTW The green color of "HNO3"'s "light green crystals" would most likely be due to the presence of praseodymium as Pr(III),
which is pale green. Other colored rare earth trivalent salts are variously pale pink and pale violet, AFAIK.
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HNO3
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| Quote: | | It is readily available from telescope making suppliers, as an agent for polishing home made telescope
mirrors. |
Any links with resonable shipping?
\"In the beginning, God...\" Wait a minute, God doesn\'t exist!!!!!!!!!! \"OK, in the beginning, ummm, hydrogen...\" Wait a minute, what about the
laws of thermodynamics? \"OK, in the beginning, ummm.....UMMMMM, what\'s left to choose from?
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neutrino
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As always, I recommend ebay. Specifically, you might find this interesting.
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HNO3
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Thanks. I think I know what I'm getting myself for Christmas.
\"In the beginning, God...\" Wait a minute, God doesn\'t exist!!!!!!!!!! \"OK, in the beginning, ummm, hydrogen...\" Wait a minute, what about the
laws of thermodynamics? \"OK, in the beginning, ummm.....UMMMMM, what\'s left to choose from?
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Marvin
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For Misch metal that is mostly cerium group, as opposed to yttrium group, from the chlorides, adding sodium sulphate preciputates the cerium group.
The precipitated sulphates are then boiled with sodium hydroxide and then washed with water until free of sulphate. The hydroxides are neutralised
with nitric acid until only slightly basic. This nitrate solution with pot bromate and a few marble pieces will deposit the cerium as basic salts on
boiling.
Its a bit of a mess but its a good method for cerium salts.
As for isolating the metal the best process listed here is to dehydrate ceric chloride in an atmosphere of HCl, add very small amounts of NaCl, KF,
BaCl2 and electrolyse in an iron crucible as the cathode using a graphite anode. Metal is then around 98% pure. Other listed methods produce <90%
pure metal, like thermite, cerious chloride electrolysis, reduction by calcium or potassium.
CeO2 for polishing tends to be of variable purity, but the bigger problem is its very hard to make it react with anything. I had some success with
prolonged strong sulphuric acid, made some nice vivid yellow solutions and deep orange crystals of ceric sulphate. Only a small amount of the CeO2
reacted. btw, how radioactive was your misch metal or didnt you test it?
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HNO3
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| Quote: | | Quote: | Thanks for the info.
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btw, how radioactive was your misch metal or didnt you test it? |
Didn't test it for radioactivity, my geiger counter (from the 60s) didn't register known-to-be-radioactive sources: Plz don't ask about the sources . Really I don't care.
\"In the beginning, God...\" Wait a minute, God doesn\'t exist!!!!!!!!!! \"OK, in the beginning, ummm, hydrogen...\" Wait a minute, what about the
laws of thermodynamics? \"OK, in the beginning, ummm.....UMMMMM, what\'s left to choose from?
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JohnWW
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Several of the rare-earth elements from praseodymium to lutetium, and also hafnium, tantalum, and rhenium, have long-lived naturally occurring
radioactive isotopes, especially the odd-numbered ones. This arises due to the existence in them of partially-filled neutron and proton shells (both
of which are completed in Pb-208) close to the nuclear size limit for stability. One of them, promethium, has no naturally occurring isotopes at all,
the longest-lived having half-lives of only a few years, although macro-quantities of its pink salts have been prepared by neutron or proton
bombardment of the heavier isotopes of neodymium.
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