Ok, so in this video I will be showing you how to extract reasonably pure yttrium salts
from the coating of fluorescent lightbulbs, and my attempt at reducing some to yttrium
metal.
The first step is to wash/brush off coating using water as a liquid in which to suspend
the powder, and a testube cleaning brush to just scrape it off.
The powder comes off very easily, and consists of yttrium oxide doped with a couple percent
europium as oxide; and lanthanum phosphate, doped with terbium and cerium, I think at
a similar concentration.
Anyway, you can see this process here on the video with a compact energy-saving bulb.
I also managed to obtain a long strip-light type bulb, and used that as well.
This obviously contained a lot more material, enabled me to make this video!
The next step is to add concentrated sulphuric acid to the water suspension of fluorescent
material.
This dissolves the yttrium and europium oxides, but leaves the lanthanum, cerium and terbium
phosphates intact, because these are insoluble in water, and the addition of sulphuric acid
wouldn't bring them into solution.
I used 5ml (an excess) of concentrated acid for the amount of solid you see here.
At this point also ensure there is sufficient water to dissolve all Y2(SO4)3, otherwise
a solid mass will result.
I then poured/filtered off the solution to leave LaPO4, TbPO4, CePO4 in the filter paper.
These will hopefully be separated in a later video.
After filtering, we need to crystallise out most of the Y2(SO4)3 to concentrate Eu in
the solution.
This will provide a pure sample of yttrium sulphate, for use in studying the chemistry
of yttrium.
Filter the solution when hot, because lanthanide sulphates exibit an inverse solubility profile,
meaning they are less soluble in hot water than cold.
The amount I ended up with was considerably less than I had expected, however, future
extractions will raise the quantity.
I then attempted to separate out the Eu by reducing it with zinc to precipitate EuSO4,
then filtering it off, redissolving in a mixture of sulphuric acid and hydrogen peroxide, followed
by crystallisation.
This didn't really work, probably due to the low concentration of Eu.
I just stored a mixture of Eu and Y sulphates for later separation with more material.
Unfortunately, I didn't film the next few steps, however, I will describe it in detail.
I added excess NaOH to Zn/Y solution, and filtered off the Y(OH)3.
Zinc would form a soluble complex with the hydroxide ions, and so remain in solution.
A yellow precipitate formed, with no apparent reason.
It may have been Eu(II) but I thought would be unlikely due to the ease of oxidation of
Eu(II).
However, it was difficult to make the EuSO4 precipitate fully, so could well be Eu(OH)2
with Y(OH)3.
I gave up on Eu, assuming I had separated it out earlier, and continued regardless.
I added the Y(OH)3 to HCl and added NH4Cl.
The purpose of this was to help form the anhydrous salt when I evaporated solution to dryness.
The YCl3 would form a hydrated double salt with the ammonium chloride, which would then
decompose releasing ammonium chloride and water vapour, leaving anhydrous YCl3 behind.
Simply heating hydrated YCl3 results in the formation of its oxide.
The reason for using a halide rather than oxide was to raise the heat and entropy of
the reaction and hopefully make it go forward more easily.
I then heated the result in a crucible, leaving the anhydrous salt behind.
The next step was to grind the YCl3 to a powder and reduce it.
I hoped to use very finely divided sodium to reduce the yttrium chloride, however, I
had a few difficulties in doing so.
I used toluene as an inert solvent with a high enough boiling point to liquify the sodium.
Then with powerful stirring, I added the sodium, and it form lots of tiny balls.
This form is commonly known as atomised sodium.
I used a bent iron wire rather than my usual teflon stirbar, because molten alkali metals
will corrode teflon.
I then cooled the flask with ice and stirring to prevent the sodium clumping togther again,
and sieved it off.
To my suprise, it caught fire which I should have known because I was using finely divided
sodium.
The alkali metals are pyrophoric anyway, and I had massively increased the surface area.
I tried again, this time with the plan of dunking the sieve into acetone to prevent
reaction with the air.
Turns out, sodium reacts with acetone.
It causes it to undergo an aldol-type reaction forming pinacol, a vicinal tertiary diol,
and some polymers.
I used 1g Na to 2.5g YCl3, and gave up using sodium.
I dismantled a lithium battery, and chopped up that lithium.
I then mixed it with the yttrium chloride, and placed it in a crucible.
After placing a lid on top to help exclude air and oxidation, I heated the crucible with
a blow torch to red-heat for a couple of minutes.
After cooling, the result was a solid, slightly powdery material
with a few metallic glints amongst the slag.
I separated out what seemed to be the best pieces, and you can see them here.
They are nothing like what I was hoping for, but I hope that they are yttrium metal.
I have no way of testing it.
Perhaps a future attempt will result a better result.
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