Sciencemadness Discussion Board - Obtaining rare earths from around the house

Pulled this off Wikipedia...

Quote:

Madagascar and Iveland-Evje region in Norway have the only deposits of minerals with high scandium content, thortveitite (Sc,Y)2(Si2O7) and kolbeckite ScPO4·2H2O, but these are not being exploited.[12]

... I always wanted to go to Norway, wanna come? Pack a pick axe, on second thought, as the mineral is called thortveitite... pack a hammer

[12] is a market report about scandium, I've done the courtesy of attaching it here for those interested in scandium in general.

Attachment: Scandium report.pdf (82kB)
This file has been downloaded 672 times

[Edited on 9-4-2014 by deltaH]

Zyklon-A - 9-4-2014 at 06:21

Oh, I guess I was wrong. I remember hearing that approximation of gold-titanium, I don't remember where.
There is surprisingly little, information on scandium in the book.
I'm hand typing this so bare with me:

Quote:

Scandium heads a list of 10 metals called the first row transition elements, which occupy the center of the periodic table. As the number protons in the transition elements increases across the row of these elements, electrons are added to an incomplete inner shell, rather than the outer valence shell. Consequently, the number of valence electrons is virtually the same for all of these elements.
Scandium is a scarce element that makes up approximately 0.0025% of the earth's crust. Scandium is a very lightweight metal with a fairly high melting point, and a good resistance to corrosion. These property's have made it of great interest to the aerospace industry in the production of aircraft. The pure metal was not available until 1937, and some of the first samples of the silvery-white metal were produced for the US air force. Pure scandium is usually prepared by electrolysis of ScCl₂. It has a tendency to develop a yellowish color when exposed to air.
Scandium has few useful compounds. The metal itself has found some use in electric devices, such as high-intensity lamps that produce light with a color close to that of natural sunlight. Lamps of this kind are often used to illuminate football and baseball stadiums.

Sorry, it looks like it took away all my paragraph breaks, and margins. Which makes it harder to read, I took the time to hand type this, so at least take a few seconds and read it.

[Edited on 9-4-2014 by Zyklonb]

eidolonicaurum - 9-4-2014 at 07:23

If anyone can find/work out/discover/stumble up a method of separating praseodymium and neodymium without having to fractionally crystallise or use ion-exchange columns, that would be both a huge relief anr a massive breakthrough! On the other hand, if cheap/readily available ion-exchange resin is available, that too would be very useful. However, I expect it will be rather expensive (I havent looked, but it just seems to be).

Zyklon-A - 9-4-2014 at 07:27

It wont be easy, but maybe possible. But even if we can't get praseodymium and neodymium, the rest would be great!

eidolonicaurum - 9-4-2014 at 07:37

Quote: Originally posted by Zyklonb

what about cerium from ferrocerium flints?
[Edited on 9-4-2014 by Zyklonb]

I've investigated these too, only theoretically for the time being because I don't have any yet, but that procedure is very similar. According to wikipedia, they contain:

Quote:

Element Iron Cerium Lanthanum Neodymium Praseodymium Magnesium Percentage 19% 38% 22% 4% 4% 4%

The iron is present as the oxide. My theory was to use this fact to avoid dissolving the iron, since I have had difficulty deliberately dissolving ferric oxide before, so this should separate it out. An identical method to the NiMH batteries could then used to separate the remaining elements.

blogfast25 - 9-4-2014 at 08:41

Praseodymium/neodymium separation should be one of the easier ones because Pr shows a IV oxidation state that Nd doesn't. There are plenty of threads here relating to Nd from neomagnets by the resident RE nutters, 'Brain&Force', 'Mr Home Scientist' and myself.

Setting up a resin exchange column needn't be expensive at the hobby level. But detecting the various fractions isn't so easy.

RE prices have come tumbling down in recent years: simply buying the elements or some of their compounds has become within reach of the hobbyist. It will often be cheaper than to extract them from stuff, no matter how much fun that can be.

Yttrium sulphate from Y-Gadolinite:

http://www.sciencemadness.org/talk/viewthread.php?tid=28071#...

[Edited on 9-4-2014 by blogfast25]

MrHomeScientist - 9-4-2014 at 08:47

I see you included my blog under neodymium! The source of that procedure (and the results of my attempts at it) are here on the forum, in The trouble with neodymium... thread. There's a ton of information there, way more than on my blog.
Spoiler alert: I was never able to get much of anything out of that method. Just a few tiny flakes of what might be the metal. Work in progress!

eidolonicaurum - 9-4-2014 at 11:01

It certainly does appear that extracting the metal from a rare earth compound is extremely difficult, but half the procedure is separating and purifying the different compounds. Even if the metal cannot be obtained, I expect a lot of fun can be had with just the compounds alone.

With regards to detecting the various different fractions in a resin exchange column, could the colour not be used, or is there a glaring error with this idea? I have never seen one of these columns, so I have no idea. I understand the principle though. Alternatively, the fluorescence of some of the compounds, along with other unique properties could possibly be used? eg different colour in different lights etc

Bert - 9-4-2014 at 11:57

Quote: Originally posted by deltaH

I would be very intrigued to hear from members here who may know of other places scandium alloys may be lurking...

In the USA, ask a gunsmith?

The revolvers in particular seem to have a durability problem, should be some scrapped frames out there.

Brain&Force - 9-4-2014 at 12:00

And I shall complete the trio of rare-earth nutters!

The more distant the lanthanides are on the periodic table, the more likely you are to separate them. Seperating, say, neodymium and ytterbium is easier than erbium and holmium. Note that many RE salts are colorless, but the colored ones can be identified quite easily. These would be cerium, praseodymium, neodymium, samarium(II), europium(II), holmium and erbium.

Some glasses contain praseodymium, neodymium, and erbium as colorants. Green laser pointers contain neodymium yttrium orthovanadate. Ytterbium is used in some forms of stainless steel. The SoundBug gadget contains Terfenol-D, which is an alloy of iron, terbium, and dysprosium. Gadolinium is used in contrast agents, and some high quality magnets may use dysprosium and holmium as polepieces.

If you want to seperate cerium, praseodymium, europium, and terbium, you can oxidize them to a higher state (or reduce it in the case of europium, which I have started a thread on). I have some information on terbium and how to seperate it from iron if it's an impurity, but I don't know about seperating it from other

Scandium is actually less abundant in earth's crust than it should be, but most of the problem arises from the fact that scandium has a very small atomic radius and doesn't deposit with the lanthanides. The uses of scandium are also pretty few and far between, though it can be used to strengthen aluminum.

As far as I can tell, lanthanides don't fluoresce in solution, so this may present a problem for tracking them in mixtures.

elementcollector1 - 9-4-2014 at 12:04

And then there's me, attempting to be a rare-earth nutter on the side but not really succeeding.
I wish there were better sources for more of the RE's, but I had no clue about the NiMH batteries. Is this a similar composition to mischmetal?

phlogiston - 9-4-2014 at 12:07

For your list: you can get tungsten welding electrodes with lanthanum or cerium (usually around 1 to 2%) as an alternative to thorium-containing electrodes.
Also, some gas mantles may contain rare earth oxides these days (also replacing thorium), but I recall most use zirconia.

deltaH - 9-4-2014 at 12:08

Excellent suggestion Bert and nice link, thanks.

aga - 9-4-2014 at 13:26

Wonderful.

Absolutely wonderful.

Chemosynthesis - 9-4-2014 at 13:39

Extremely curious about your video to come!
I've been looking at working with praseodymium and I would be using the chloride route as per a modified procedure of J. Inorg. Nuc. Chem 1962, Vol. 24, pp. 387-391.

Dan Vizine - 9-4-2014 at 14:55

Quote: Originally posted by deltaH

I have always been fascinated by scandium, .... but simply because it appears to hardly have practical applications ...

According to tables of natural abundance of elements in the earth's crust, scandium's abundance is comparable to cobalt

Meanwhile, tellurium, with an abundance similar to gold, trades around $110/kg

Supply and demand :mad:

Actually, if Scandium were cheaper you'd see it everywhere. It has excellent structural properties. Verry high end bicycle frames (and other parts) were made of scandium or (more likely) scandium with alloying additions.

Abundance is not in any way to be confused with ease of isolation from nature. The paramount factor is beneficiation (concentration). That is, if nature gathers it together, it's cheap (generally). Think Monazite sands, ore veins, etc. Some elements (Rb for example) simply don't have ores. They are "widely dispersed" and thus costly. High processing costs (isolation & purification) are secondary.

[Edited on 9-4-2014 by Dan Vizine]

Subcomputer - 10-4-2014 at 01:19

elementcollector: for what it's worth, the wikipedia article looks like it says that NiMH batteries using high lanthanum mischmetal or lanthanum improved mischmetal have been on the market, but that doesn't mean much as to whether the batteries you get will be of a certain purity. Especially with mischmetal industrially meaning essentially "the lanthanum-cerium and whatever RE else that's left over after it's no longer economically viable to separate out the good stuff", and that was before the survival kit companies decided to redefine terms to include ferrocerium, added magnesium, etc.

Speaking of dropping prices, I bought 10g each of ampouled "cerium" for ~$12 and "neodymium" for ~$16 from ebay seller yaolihong2013 . Can't wait to see what I actually get.

blogfast25 - 10-4-2014 at 04:40

With regards to detecting the various different fractions in a resin exchange column, could the colour not be used, or is there a glaring error with this idea?

Many of these compounds are colourless, and the colourful ones often are only that in quite concentrated solutions (something ion exchange resins don't 'do' well)

Even Classic XRF apparently isn't capable of telling them apart: the techniques has to be combined with XRD to separate the emissions, which are very close together in terms of eV.

I'm not sure but I think detection of REs in an ion exchange eluate would be by means of UV/VIS spectrometry.

Dan Vizine - 10-4-2014 at 05:00

The first chromatography I ever did in my life was the separation of 6 RE compounds on ion exchange resin in a freshman chemistry class. Each RE compound was visually detected in the eluate. They were all different colors. Unfortunately the identities of the compounds are lost in the mists of time.

That being said, I think chromatography is your best bet. Fractional crystallization is generally a horribly lossy and labor intensive process.

Is your goal to experiment or attain samples? It will be cheaper to buy RE materials than separate them (probably). If this is a learning exercise, have at it. Good luck!

blogfast25 - 10-4-2014 at 05:52

The first chromatography I ever did in my life was the separation of 6 RE compounds on ion exchange resin in a freshman chemistry class. Each RE compound was visually detected in the eluate. They were all different colors. Unfortunately the identities of the compounds are lost in the mists of time.

Visually as in 'by the naked eye'? No photometric detection?

[Edited on 10-4-2014 by blogfast25]

Dan Vizine - 10-4-2014 at 06:42

Think small college, early 70's, freshman lab....nope, just eyeballs.
It worked remarkably well.

blogfast25 - 10-4-2014 at 08:13

A remarkable exercise for a freshman lab, IMHO.

Maybe I'll have to reconsider and clean our local tobacconists out of ferrocerium.

Dan Vizine - 10-4-2014 at 13:25

Y'know, I could be wrong about the stationary phase. I really can't remember if it was ion exchange resin or something like alumina. It could even have been silica gel for all I know, although alumina maybe makes more sense.

eidolonicaurum - 10-4-2014 at 23:09

So how would a chromatography column be set up? Is it simply a long tube (how long?) filled with aluminia, silica gel, resin of some sort, etc.? I am a complete novice when it comes to these sorts of things.

[Edited on 11-4-2014 by eidolonicaurum]

blogfast25 - 11-4-2014 at 05:36

So how would a chromatography column be set up? Is it simply a long tube (how long?) filled with aluminia, silica gel, resin of some sort, etc.? I am a complete novice when it comes to these sorts of things.

[Edited on 11-4-2014 by eidolonicaurum]

My Shriver and Atkins 'Inorganic Chemistry' practically gives a recipe for it. I'll try and dig it up tonight.

[Edited on 11-4-2014 by blogfast25]

Dan Vizine - 11-4-2014 at 06:18

My Shriver and Atkins 'Inorganic Chemistry' practically gives a recipe for it. I'll try and dig it up tonight.

[Edited on 11-4-2014 by blogfast25]

Quite generally, here is how you prepare a chromatographic column.

Just as you said, a chromatography column is nothing more than a long tube with some kind of stopcock at the bottom to control flow. The amount of material the column can handle at once is a function of the column's diameter. The degree with which it can separate different materials is a function of the column length.

To fill a chromatography column, follow this procedure. If the column has a fritted glass disc at the bottom, you're good to go. If it doesn't, you need to make a ball of glass wool and push it down there. The function of this is to keep the stationary phase (the solid) inside the column and out of the stopcock. Next, take a large beaker and fill it with somewhat more adsorbent than your column can hold (this is dry packed material, it will settle). Add enough of whatever solvent you intend to run the column with (called the eluent) and stir the mixture until you have a slurry free of bubbles. That bubbles thing doesn't sound too important, but it is. In fact, uniformity is probably the single most important aspect of filling the column. Discontinuities between successive pours should be minimized as much as possible. Pour some of the slurry into the column with the bottom stopcock opened. As the liquid level runs down low enough to allow an additional pour of the slurry to be made, do so. Rapping on the side of the column with a cork ring or your knuckles helps the solids settle evenly. The top surface should be absolutely flat when the column has been totally poured. Close the stopcock when you have added sufficient stationary phase. Leave enough space at the top of the column for solvent to be added, several inches at least. Cover the top of the adsorbent with a layer of heavy sand, maybe a quarter of an inch to a half an inch thick. Alternatively, take a piece of filter paper the same diameter as the column and punch dozens of tiny holes in it with a pencil point. Lay this on top of the adsorbent. Either of these methods serve to defuse the stream of fresh solvent added to the top of the column.

Dissolve the material to be separated in the minimum amount of solvent. This is crucial because the width of the band of material you apply to the top of the column has everything to do with how well it will separate. The thinner the band, the cleaner the separation generally. Using a pipette, slowly add this material to the top of the column. Open the stopcock and allow this band to slowly adsorb into the top layer of the stationary phase. Follow this by fresh solvent also added by a pipette for fine control. Once the band has started moving down the column, you can pour additional solvent in from a beaker. An elegant solution to this need to add solvents regularly can be achieved using a separatory funnel. Fill the separatory funnel all the way with solvent. Put the stopper in and use supports to position the drain of the separatory funnel an inch or two above the sand in the column. Open the stopcock of the separatory funnel slowly. At first solvent will flow out somewhat quickly, this will rapidly come to a stop due to the vacuum generated inside the funnel. When the level of the liquid in the chromatography column goes below the tip of the separatory funnel, air leaks back in and solvent comes out until it once again prevents air from getting in. This process repeats over and over and will maintain a level of liquid inside your chromatography column without continual work on your part.

The stationary phases which are commonly used are neutral alumina, basic alumina, silica gel, reverse phase silica gel and ion exchange resins. This is not an exhaustive list, many things can be used as adsorbents but these are the most common. Refer to the literature for the stationary phase most appropriate to the materials you are separating. Silica gel generally has the best resolving power. However silica gel is considered to be slightly acidic and is not appropriate for all compounds. Alumina, any of the kinds, generally interacts with most organic molecules less strongly than silica gel. They also will allow chromatography of things which fall apart on silica gel. Reversed phase silica gel is a specialty product and very expensive, you don't need to consider this. Ion exchange resins look like little tiny plastic beads. Their most important use is for ionic compounds. Not only can they be used to chromatograph materials but they will also swap out the anion or cation depending if you are using an anion exchange resin or cation exchange resin.

The polarity of the solvent used to elute the material down the length of the column determines how fast the material moves, how well it separates from other materials as well as the broadness of the band as it moves. Solvent mixtures are very frequently employed. Sometimes the relative amounts of two solvents are varied as the process proceeds, but this complication is generally not needed for regular organics. It seems to enjoy more use with biologicals. The solvent must have good solubility for your compound and must have sufficient polarity to allow you to run the column in a reasonable length of time with reasonable volumes. As the solvent runs out of the bottom stopcock, you collect it in many small fractions. The contents of these fractions are assayed by any one of a number of methods. Being primarily an organic chemist, I heavily favor thin layer chromatography plates. You simply make a spot of each fraction at the bottom of the plate, put the plate into a jar containing a tiny bit of solvent in the bottom, and as the solvent absorbs up the length of the plate it performs a mini chromatography. You examine the plates by shortwave or longwave ultraviolet light, by placing them in a chamber filled with iodine vapors, by spraying them with a mixture of alcohol and sulfuric acid and then heating them until the organic compounds char, by examining them with UV/VIS light, by spraying with o-vanillin/alcohol/sulfuric acid and heating or any other method you can think of which will allow you to discriminate among them. There are developing reagents which will detect non-aromatic hydrocarbons, even alkanes. Fractions containing comparably pure material are combined and evaporated to give you back your purified component.

This was dictated using voice recognition, so if you see any craziness, blame it on that. I'll undoubtedly edit this as the day goes on and I find more errors.

[Edited on 11-4-2014 by Dan Vizine]

[Edited on 11-4-2014 by Dan Vizine]

Bert - 11-4-2014 at 06:50

The term "elute" eluded the voice (non) recognition software-

Dan Vizine - 11-4-2014 at 07:50

Quote: Originally posted by Bert

The term "elute" eluded the voice (non) recognition software-

I can't even find the word elute in there. Although "eluant" is spelled wrong, eluent is correct.

Ohhh! Now I see it, thanks.

[Edited on 11-4-2014 by Dan Vizine]

blogfast25 - 11-4-2014 at 10:25

From 'Inorganic Chemistry' (Shriver and Atkins, third edition), my interpretation:

For resin, sodium polystyrene sulphonate can be used. If I’m not mistaken that’s box standard Dowex ion exchange resin, normally used to exchange cations for H+. Soak in brine to ‘load’ fully with Na+. Then wash with deionised water, then with eluent solution.

Eluent solution is an ionic citrate, lactate or better a 2-hydroxy isobutyrate, probably about the same concentration as the RE solution.

Load the column (a burette, for instance) with resin, add eluent (note the volume used), then load the top with dissolved Ln3+ salts. A second burette, ‘coupled’ to the first one could be used to administer the eluent. Open stopcock of the top one fully, then open stopcock of the column to get a steady drip.

It works because of the competing equilibria: ion exchange of Ln3+ with the resin and complexation of the Ln3+ by the complexing agent. The smallest (thus heaviest) REs elute out first.

Quite doable. Another one on my ‘list of things to do before I leave this mortal coil’…

[Edited on 11-4-2014 by blogfast25]

eidolonicaurum - 11-4-2014 at 11:22

Could I therefore use a burette filled with silica gel beads as the stationary phase to separate these rare earths? And what else could I use this set up to separate, eg could a mixture of d-block salts be separated using this method?

Chemosynthesis - 11-4-2014 at 12:12

Excellent post, Dan!

One caveat about the wool plug for an unfritted column is to only use a small amount. It's to keep sand from etching your stopcock, so a tiny amount to just keep your packing level is sufficient. Do not forget it or you will create a permanent leak (until you replace the stopcock).

Silica and alumina are pretty standard column materials for column chromatography. One tip I learned is that you can pour a thin layer of sand on top of your packed column prior to adding more solvent, to avoid disrupting the evenness the top of the packing. It's not necessary, but can be helpful to keep bands straight, and narrow down your fraction selection/maintain resolution.

Do not let your column dry out with product inside. You need to keep the solvent level above your stationary phase by refilling. The thin sand toplayer trick can help out there. If you have to leave a column overnight, try to wrap it in foil and foil/parafilm the top to keep your solvent system from evaporating. The easiest way I am familiar with to unpack a column is a very light stream of compressed air through the tip, with the column aimed into a trashcan. If you have compressed gas that is unreactive to your chromatography system, check out flash chromatography. I always hated gravity chromatography because of the time consumption. I ran plenty in synthesis before getting into better funded labs and switching fields.

Edit- check out these articles... you might need to manually run a gradient, which I always found annoying, or run multiple columns. Silica gel with nitric acid eluent is mentioned. I haven't run that system before, so be careful when mixing since you might heat the column. DMSO and silica, if I recall correctly, can heat up. I remember seeing people crack columns that way.
http://pubs.acs.org/doi/abs/10.1021/ac00277a069
http://www.chemeng.lth.se/exjobb/E546.pdf

[Edited on 11-4-2014 by Chemosynthesis]

eidolonicaurum - 11-4-2014 at 12:41

If I had, say, 100ml of substance in solution, how would that be processed in a burette sized column? Would I pour it in bit by bit and separate the whole lot at once or put some in, separate the components, add more and repeat the process?

blogfast25 - 11-4-2014 at 12:44

Could I therefore use a burette filled with silica gel beads as the stationary phase to separate these rare earths?

I don't see how alumina or silica, without some surface treatment, can possibly retain RE ions.

In Seaborg's 'The Transuranium Elements' there are plenty of references to separating REs or actinides using Dowex-1 or Dowex-50 resins and 0.2 M citrate buffer as eluent. Not a word about alumina or silica though. Chemosynthesis' second reference does use silica gel and di-(2-ethylhexyl)
phosphoric acid (good luck getting that!) as eluent.

Dowex style ion exchange resins aren't hard to obtain.

If I had, say, 100ml of substance in solution, how would that be processed in a burette sized column? Would I pour it in bit by bit and separate the whole lot at once or put some in, separate the components, add more and repeat the process?

That wouldn't work: for a 25 ml burette you would have to concentrate all substances in a few ml at most. For a 100 ml you'd need a much wider column bed, like several cm radius.

[Edited on 11-4-2014 by blogfast25]

Chemosynthesis - 11-4-2014 at 12:51

You almost have to do it at once or your different materials can begin to overlap among samples. The only way to do them piecemeal is to know your resolution, theoretical plates, etc. I never did any of that.

Dissolve your substance in just enough solvent to get an even coating of your sand. I always liked using the sand topcoat because, as I alluded to, this step can depress some sand, but should leave the stationary phase flat. Flat, narrow/sharp bands are key in any kind of chromatography, including gel electrophoresis, which I am finishing a bunch of right now. Once you have your coating, you should very gently try to pour on your solvent, possibly using a stir rod or something to disperse the pressure along your column wall. I would rotate my stirring rod around to avoid hammering one of sand with solvent.

Once you fill up pretty high, you are now ready to open the stopcock and fill up your tubes. If you run a lot of tubes, you need a big rack and a couple hours time, possibly. Make sure you have a system of tube filling order. Always go left to right, or always zig zag. Whatever you like... keep it consistent so you never lose track of your tube count. Just as Dan Vizine said above with TLC being an excellent way to determine your solvent system... TLC is also an excellent way (only way?) to determine your fractions. TLC every single tube you fill, and make notes on which eluents are in which tubes. Discard/keep accordingly.

Hopefully I remembered all that accurately. I haven't done the synthesis/purification/characterization side in awhile, but want to get back into it.

Dan Vizine - 11-4-2014 at 16:17

Thanks, Chemosynthesis, likewise with your contributions.

Blogfast, At a very basic level, all a molecule needs to be retained on any of these phases is a dipole moment or a charge or even high polarizability. Even alkanes don't have Rf values of 1.0 in all solvents.

For those who may not know the term, Rf = distance material moves on a tlc plate divided by the distance the solvent traveled. Generally, higher polarity = lower Rf

But actually, eidolonicaurum, this is something you will need to read about to do. Our explanations will not be good enough given the time & space, etc. Blogfast's specifics are a push in the right direction. Dowex is the most universally used ion exchange resin and it is tiny golden colored beads. Columns will run very quickly. This is not always the best thing, resolution may suffer and you'll want to throttle the flow a bit in all likelihood.

Btw, Silica gel (SiO2) and alumina are white powders.

Every chromatography I've ever done which had water as a co-solvent on silica gel always brought a tiny amount of an inorganic residue with it.
You won't have this problem at all with Dowex beads.

To totally change the form of the resin, run 5 bed volumes of an aqueous soln of the desired ionic form through the column followed by 3 volumes of distilled water. More washing is better if you have the time/ambition.

[Edited on 12-4-2014 by Dan Vizine]

Chemosynthesis - 11-4-2014 at 20:16

Thanks, Chemosynthesis, likewise with your contributions.

I appreciate it! Posters like you and Blogfast are the reason I joined instead of lurking.

My Shriver and Atkins 'Inorganic Chemistry' practically gives a recipe for it. I'll try and dig it up tonight.

You just convinced me to get a copy of that book. I had a different upper level inorganic text in undergrad and let someone borrow it, and this is exactly the kind of text I need lying around to refresh the Jahn-Teller effect and orbital mixing for ideas on what do with the PrCl3 I was going to use in a catalysis.
Thank you.

I don't see how alumina or silica, without some surface treatment, can possibly retain RE ions.

Good call. I forgot to mention as per my
"Model Calibration of Chromatographic Separation of Rare Earth Elements" by Frida Ojala Department of Chemical Engineering, Lund University January 2010 link that di-(2-ethylhexyl) phosphoric acid (HDEHP) reagent was cited as being able to separate lanthanides on silica columns with the nitric solvent front. Maybe not the best idea.

[Edited on 12-4-2014 by Chemosynthesis]

blogfast25 - 12-4-2014 at 05:25

A bit more from Atkins and Shriver: an admittedly somewhat oversimplified guide to colours of the Ln3+ aqua ions, in function of the number of 4f electrons:

0 or 14: colourless
1 or 13: colourless
2 or 12: green
3 or 11: red
4 or 10: pink
5 or 9: yellow
6 or 8: pink
7: colourless

So at Gd3+ the colour series more or less turns back on itself. It also means that out of the 14 elements, 9 have colourful aqua 3+ cations, 5 don't.

Dan, I appreciate your point about alumina/silica, but in the case of cations, a cation exchange resin really does sound like the logical choice. As you also pointed out.

And some more from The Transuranium Elements: for the actinides/lanthanides they used a Dowex-50 resin, which is essentially a sulphonated cation exchange resin, somewhat old fashioned probably (this is pre-war research). A 0.2 M ammonium citrate/citric acid buffer (pH about 3.5) was used as eluent solution, at 100 C (87 C for the actinides). A remarkable similarity in the elution behaviour between the two series was observed.

I'm not sure what the purpose of the temperature is: affecting Rf values probably.

It also describes experiments with Dowex-1, using 13 M HCl as eluent.

[Edited on 12-4-2014 by blogfast25]

Brain&Force - 12-4-2014 at 10:30

Here are the colors of different lanthanide compounds:

Lanthanum: colorless (0 f-electrons)
Cerium(IV) sulfate: yellow (0 f-electrons)
Cerium(III): generally colorless, except cerium(III) oxide is yellow(?) (1 f-electron)
Praseodymium(III): pale green - limeade color (2 f-electrons)
Neodymium: varies depending on light source: reddish-magenta to lilac in sunlight, colorless in CFL light (3 f-electrons)
Samarium (III): pale yellow (5 f-electrons) Fluoresces deep red(?)
Samarium(II): blood-red but unstable (6 f-electrons)
Europium(III): colorless to pale pink (6 f-electrons) Fluoresces red
Europium(II): yellow (7 f-electrons) Fluoresces blue
Gadolinium: colorless (7 f-electrons)
Terbium(IV) oxide: black (non-stoichiometric)
Terbium(III): colorless (either 8 f-electrons or 7 f-electrons and a d-electron, I've see both) Fluoresces green
Dysprosium: colorless (9 f-electrons) Fluoresces yellow(?)
Holmium: varies depending on light source, yellow in sunlight, pink in CFL light (10 f-electrons)
Erbium: pink (11 f-electrons)
Thulium: either colorless or green(?) (12 f-electrons) Fluoresces blue(?)
Ytterbium(III): colorless (13 f-electrons)
Ytterbium(II): green (14 f-electrons)
Lutetium: colorless (14 f-electrons)

Would separation through magnetism be feasible at all? Just an idea...

blogfast25 - 13-4-2014 at 05:29

Would separation through magnetism be feasible at all? Just an idea...

No idea.

Incidentally, the 4 % Ho oxide in HClO4 standard for spectrophotometers is decidedly pink, at least as shown in Wiki...

elementcollector1 - 13-4-2014 at 12:43

Half off-topic, but I just calcined a (presumably) 2:1 mix of Ce and La oxalates to oxides. What should I do to separate these two? According to the Wiki page, cerium salts are insoluble in nitric acid, but I'd rather avoid that, as I don't have any nitric acid and don't want to go to the trouble of distilling it for this one purpose.

Chemosynthesis - 13-4-2014 at 13:01

Half off-topic, but I just calcined a (presumably) 2:1 mix of Ce and La oxalates to oxides. What should I do to separate these two? According to the Wiki page, cerium salts are insoluble in nitric acid, but I'd rather avoid that, as I don't have any nitric acid and don't want to go to the trouble of distilling it for this one purpose.

This has a good procedure of the type you describe... which unfortunately, uses nitric acid.
http://link.springer.com/article/10.1007%2FBF00468565#page-1

Seems better than my next alternative from Indian Journal of Chemistry Vol. 44A, March 2005, 497-503... which suggests N-phenylbenzo-18-crown-6-hydroxamic acid, or the solvent impregnated resin of http://dx.doi.org/10.1016/j.seppur.2013.07.047
and similar un-home-friendly sounding reagents here:
http://dx.doi.org/10.1016/j.hydromet.2003.10.008

I hope I'm wrong, but it looks like nitric might be your best bet. That or borrow a gas centrifuge.

blogfast25 - 13-4-2014 at 13:13

Try fusing the oxides with an excess NaHSO4 for about an hour or so. This should convert the La2O3 to the La sodium double sulphate which is very poorly soluble. Assuming the Ce was present as CeO2 that should convert to Ce(SO4

2 which is relatively soluble.

This is assuming the calcination of the oxalates to oxides was successful.

[Edited on 13-4-2014 by blogfast25]

12AX7 - 13-4-2014 at 13:58

Regarding scandium, AFAIK, its use in aluminum alloys is as a modifier, similar to titanium. Titanium finds use as a grain refiner: it is present as fine TiSix (TiSi2 comes to mind?) intermetallic grains, which have low solubility in molten aluminum and act as nucleation agents, resulting in a finer, stronger crystalline structure on casting. The amount is usually < 0.1%. This is probably less important for rolled or wrought products.

My short understanding of odd Russian alloys is limited to this: they used lithium-aluminum alloys in rocket parts (skin, structural?). Whether these (or any other military or special purpose) alloys contain Sc, I don't know.

Tim

elementcollector1 - 13-4-2014 at 14:07

2 which is relatively soluble.

This is assuming the calcination of the oxalates to oxides was successful.

[Edited on 13-4-2014 by blogfast25]

Well, I obtained a tan / light brown powder of a very smooth, almost liquid consistency, so I think that a major portion got converted at the very least.

I'll have to prepare some NaHSO₄, then.

Another odd thing happened while I was doing the same with what I'm fairly sure was neodymium oxalate (all these white powders!). At first, it went rather smoothly, and the compound turned consistently dark gray. However, upon further heating around the edges of the crucible (this was done with a blowtorch), a whiter substance began to appear. Curious, I heated the gray compound further until all of it was the white compound. What could this be? In addition, it appears the white compound partially melted - upon scooping into water to check for solubility, some of the substance had collected into 'chunks'. So far, it does not appear to be soluble, so I am very confused.

blogfast25 - 14-4-2014 at 04:31

NaHSO4: pool supplies, if I'm not mistaken.

I wouldn't worry too much about that colour change: it could be caused by all sorts of things like the last but of volatile contamination blowing off. It's very hard to tell what it is precisely and colour is deceptive in any case, probably more so at high temperature. If it's nice and white it's probably fairly pure. Iron would tinge it red to brown for instance.

[Edited on 14-4-2014 by blogfast25]

MrHomeScientist - 14-4-2014 at 06:20

I'll confirm what blogfast said above - I got my sodium bisulfate from Home Depot as a pool supply called "dry acid." It's only listed as 93% bisulfate, but it's worked for my purposes so far. I just add a bit extra dry acid to make up the difference. I used mine to isolate bromine.

elementcollector1 - 14-4-2014 at 10:06

I wouldn't worry too much about that colour change: it could be caused by all sorts of things like the last but of volatile contamination blowing off. It's very hard to tell what it is precisely and colour is deceptive in any case, probably more so at high temperature. If it's nice and white it's probably fairly pure. Iron would tinge it red to brown for instance.

[Edited on 14-4-2014 by blogfast25]

Maybe. I've always heard of Nd₂O₃ being gray or grayish-blue, never white. Plus, it remains just as white when cooled...
A thought: Are neodymium's odd color-changing properties coming into play here? Looking at Google Images for neodymium oxide, there are two versions of the same photo: One with my coloration, and one with what I consider the 'standard' blue-gray.
I'm going to try calcining it one more time - couldn't hurt, right?
After that, I'll try some acids to see if it really is neodymium.

As for the bisulfate, I'll take a look around.

blogfast25 - 14-4-2014 at 12:32

My own homemade neodymium (III) oxide was very light beige. I was sure it was at least 99 %. I'm not too worried about these slight differences...

Dan Vizine - 14-4-2014 at 15:49

Quote: Originally posted by 12AX7

Regarding scandium, AFAIK, its use in aluminum alloys is as a modifier, similar to titanium. Titanium finds use as a grain refiner: it is present as fine TiSix (TiSi2 comes to mind?) intermetallic grains, which have low solubility in molten aluminum and act as nucleation agents, resulting in a finer, stronger crystalline structure on casting. The amount is usually < 0.1%. This is probably less important for rolled or wrought products.

My short understanding of odd Russian alloys is limited to this: they used lithium-aluminum alloys in rocket parts (skin, structural?). Whether these (or any other military or special purpose) alloys contain Sc, I don't know.

Tim

The lithium-aluminum alloys had strength similar to steel. Similar to the strength exhibited by stir-plates tops of aluminum with a little copper (Dural, I think). Are these two basically the same thing, inappropriately sized impurity atoms screwing up the smooth slide of slip faults, teamed with creating smaller grains, or is it deeper than that?

Re. Sc in Al, Wiki says:The positive effects of scandium on aluminum alloys were discovered in the 1970s, and its use in such alloys remains its only major application. You could probably expect to see this in applications where cost is secondary, military or not.

[Edited on 14-4-2014 by Dan Vizine]

Brain&Force - 14-4-2014 at 17:00

MiG-29 components contain scandium-aluminum alloys.

One of the problems with scandium as a pure metal is that it splits water to form the hydroxide. This excluding its low concentration and high cost. Scandium turnings are also highly flammable.

I'm interested as to what alloys one can form with lithium, magnesium, aluminum, scandium, titanium, and yttrium. All of which are light metals that form strong alloys. The problem is making them and forming them - again, these alloys tend to burn instead of melt.

12AX7 - 14-4-2014 at 23:54

Dunno. The phase diagram looks surprisingly typical (a thick intermetallic in the middle, usually suggesting a brittle, fairly strong phase, with aluminum with solid solubility on one side, and more intermetallics towards the lithium side), so it would be precipitation hardening without a doubt, like most aluminum alloys (Cu, Mg, Si and Zn among the most important).

AFAIK, interstitial (dissolved) atoms add a little strength, but as I recall, 6061-T0 (annealed) isn't too much stronger than most other non-hardening alloys (1000 series, 3003, etc.). Which are still a lot stronger than pure aluminum (1199 I think?), which is just ridiculously soft (like lead), but a long ways to go compared to 6061-T6 (worked, precipitation hardened and aged) or others.

As for scandium and other grain refiners, I guess you could figure those act to prepare the microstructure for what it's best at. Crystal boundaries are weak, so having many of them means more strength (very crudely). The intergranular impurities also act as wedges, locking slip planes around and between crystals. I expect this isn't as important for worked material (deformation elongates and refines the crystal structure already), but maybe it's still fairly useful. And of course, precipitation hardening involves creating very fine particles (<1um IIRC) which lock slip planes within a crystal.

That's about the extent of my knowledge on this... I've forgotten so much metallurgy since I last used any of it!

Tim

blogfast25 - 15-4-2014 at 04:18

Scandium turnings are also highly flammable.

You have a reference for this?

Dan Vizine - 15-4-2014 at 08:07

Tim said "That's about the extent of my knowledge on this... I've forgotten so much metallurgy since I last used any of it!"

To which I reply....hmmm, someone who has forgotten more than I know...glad to make your acquaintance. I have an immense amount of respect for matalurgists. Metal is the exact opposite of the flat, unchanging, static thing it appears. The levels of complexity under the surface are mind blowing. Static it is not! I've been self-educating in this field for a decade, on and off, depending on my latest crazy fascination of the moment, and I only know the surface. I'm humbled by the complexity.

blogfast25 - 15-4-2014 at 08:55

On an old repeat of 'Cajun Pawn Stars' last night our pawners sold a 'scandium revolver'. It was a small hammerless revolver, quite futuristically looking, but it wasn't clear at all what part was supposed to be scandium or whether there was a scandium minority or majority alloy in the gun or what.

Dan Vizine - 15-4-2014 at 15:41

The positive effects of scandium on aluminum alloys were discovered in the 1970s, and its use in such alloys remains its only major application.-- Wiki

You could probably expect to see this in applications where cost is secondary, military or not.--Me

A few % Sc in Al is all that is needed. You get a gun light as aluminum but strong as steel. As I noted before, verry expensive. These guns set records*. In bicycles they allowed the ultimate in weight reduction. I guess it maybe didn't catch on in bikes as I never hear about it, usually Ti/Al is the thing I believe. Probably too pricey.

*not accuracy

[Edited on 15-4-2014 by Dan Vizine]

blogfast25 - 16-4-2014 at 04:43

Wait until someone finds a decent deposit, it's only a matter of time...

Zyklon-A - 16-4-2014 at 07:03

Scandium turnings are also highly flammable.

You have a reference for this?

Not exactly a reference, but here is the FIRE AND EXPLOSION HAZARDS DATA for some Scandium:

Quote:

Flash Point: N/A
Autoignition Temperature: N/E

Flammable Limits: Upper: N/E Lower: N/E

Flammability: Highly flammable

Extinguishing Media: DO NOT USE WATER or halogenated extinguishers. Use special powder for metal fires.

Special Firefighting Procedures: Firefighters must wear full face, self-contained breathing apparatus with full protective clothing to prevent contact with skin and eyes.

Unusual Fire & Explosion Hazard: Scandium dust is flammable when exposed to heat or flame or oxidizing agents. May react violently in air and to halogens. Reacts slowly with water to liberate hydrogen gas. Thin foils can be ignited by spark or static electricity.

Here's the site I found this on:Site.
You might be able to buy some scandium here - I'm not sure.

elementcollector1 - 16-4-2014 at 12:29

Some pictures of my 'mischmetal oxide' and neodymium oxide, made by calcining their oxalates via blowtorch:

The white neodymium oxide:

I swear, the cerium/lanthanum oxide isn't nearly this brown in reality - more of a dark tan.

The neodymium was purified from magnets using HCl, then oxalic acid. The lanthanum/cerium mix was purified from mischmetal rods (those from magnesium firestarting blocks) using the same method.

blogfast25 - 16-4-2014 at 12:52

. The lanthanum/cerium mix was purified from mischmetal rods (those from magnesium firestarting blocks) using the same method.

Did you mean "lanthanides/cerium mix"? Real mischmetal is supposed to be a mixture of more than just La and Ce... Did your rods come with a specification?

elementcollector1 - 16-4-2014 at 13:04

. The lanthanum/cerium mix was purified from mischmetal rods (those from magnesium firestarting blocks) using the same method.

Did you mean "lanthanides/cerium mix"? Real mischmetal is supposed to be a mixture of more than just La and Ce... Did your rods come with a specification?

No... but I remember a while back that the composition was 25% La, 50% Ce, bal. Fe and MgO, as well as small amounts of other RE's (<1%).
Curiously, Encyclopedia Britannica lists 50% Ce, 25% La, 15% Nd (???), 10% other RE's + iron.

blogfast25 - 17-4-2014 at 04:37

Curiously, Encyclopedia Britannica lists 50% Ce, 25% La, 15% Nd (???), 10% other RE's + iron.

Curiously? This is closer to what most chemists would expect from misch metal: mostly light REs with traces of the heavier ones... even though the EB is hardly an authority on these things.

Subcomputer - 17-4-2014 at 05:43

There is no defined mix at all for mischmetal, even the majority lanthanum/cerium mix is up in the air. It really is the mix that came out of the mine that day, once it it no longer cost effective to separate out the other REs. Essentially a waste product that has found a new life. The Fe (and Fe compounds) come from making additives for hardening it up at which point it becomes "ferrocerium", again with no particular formula as far as REs go, although there are guidelines as far as how much Fe. Mg is getting into the survival strikers, where there might be a particular breakdown for a particular brand or product, but that's about it.

Brain&Force - 17-4-2014 at 06:30

Scandium turnings burning: http://youtu.be/s1i90S0vsW8

I haven't got a clue about the bulk metal.

ESPI metals requires two trade references to order from. Try Metallium instead.

As for mischmetal and ferrocerium, it's economical now to remove the last traces of praseodymium and neodymium, so a lot of the firestarter products on the market today only contain these two lanthanides. Also note that mischmetal shouldn't contain much (if any) iron or magnesium. However, it's harder to get than the ferrocerium used in most firestarting products.

Try looking for "Rare Earth Chloride" if you want a mixture of the lanthanides - but at this point I would just order the metals online.

Dan Vizine - 17-4-2014 at 06:59

Once I bought a block of Lanthanum to section for preparing samples. I used my horizontal metal-cutting band saw and a continuous stream of sparks about an 1/2" diameter sprayed out of the cut continuously until the cut finished.

Scandium metal is frequently on e-Bay. It is simple to acquire although costly. Most "real" companies look at you and me and see zero commercial potential, unless they are hobbyist oriented. They just see liability, only to make peanuts on a sale.

There are a few people on eBay who specialize on RE's from China and Poland.

[Edited on 17-4-2014 by Dan Vizine]

blogfast25 - 17-4-2014 at 07:45

Thanks, B&F.

Dan: I hope to be one of them, 'shortly'.

IrC - 17-4-2014 at 09:21

Quote: Originally posted by Subcomputer

There is no defined mix at all for mischmetal, even the majority lanthanum/cerium mix is up in the air. It really is the mix that came out of the mine that day, once it it no longer cost effective to separate out the other REs. Essentially a waste product that has found a new life. The Fe (and Fe compounds) come from making additives for hardening it up at which point it becomes "ferrocerium", again with no particular formula as far as REs go, although there are guidelines as far as how much Fe. Mg is getting into the survival strikers, where there might be a particular breakdown for a particular brand or product, but that's about it.

This is lacking in chemistry knowledge and misleading in so many ways. Merely reading the wiki page would point this out.

http://en.wikipedia.org/wiki/Mischmetal

Neither Mischmetal nor Lanthanides (in the form of the pure metals alloyed into Mischmetal with metal oxides mixed in for hardness) 'come out of the mine' in any sense of the term. As to Fe or Mg they are added as their oxides "an alloy of only rare-earth elements would be too soft to give good sparks. For this purpose, it is blended with iron oxide and magnesium oxide to form a harder material known as ferrocerium". I think you will learn on SCM a higher level of technical competency is desired before posting anything as a 'fact' or 'facts'.

Lanthanides come primarily from Monzanite sands (and from ores mined), separated and reduced to pure metals through a very complex series of chemical procedures. Never pure metals in their natural state, the statement "It really is the mix that came out of the mine that day" just makes no sense from a technically accurate view. The metals after being refined are mixed. You do not find Ce or La metal pure in nature ever. Far too reactive. Mischmetal quite simply never 'came out of the mine that day' in any sense of the term. Being more precise and accurate in technical descriptions is to be desired over blanket statements not thought through as to scientific accuracy. Maybe some will think I am picking at details, so be it. I think it is important to point out the flaws in the statements.

[Edited on 4-17-2014 by IrC]

unionised - 17-4-2014 at 10:18

The metal never came out of the mine, but the mixture of ores did.
And, if all you want to do is make sparks, there's no point going to the expense of refining the individual metals so, the stuff in lighter flints is a mixture that contains the oxides in the same proportions as the elements were present in the ore that came out of the mine.
It's reduced to the metal and some iron and Mg thrown in.

The point being made was that nobody is likely to have analysed the stuff for the proportions of the RE metals before turning it into flints so the statement "There is no defined mix at all for mischmetal" is true- it will, for example, vary with different mines.

It is the "mix that came out of the mine" in the sense that nobody bothered to un-mix them (OK there' may have been some partial separation to get some of the more valuable ones)

Brain&Force - 17-4-2014 at 11:44

And it is "the mix that came out of the mine" because depending on the production site, the composition may vary. (Of course, as mentioned earlier, some places remove all other rare earths except lanthanum and cerium because it's cost effective.) The only important thing is that cerium is included to allow sparking.

However, this pure LaCe alloy (you know, lace would be a good name for it) is extremely soft and unstable in air. That's why other metals are added, especially Mg to allow some passivation and Fe to improve hardness and sparking. Thus you get ferrocerium. It is possible to buy pure mischmetal online - it is used in some different types of strikers because it's soft and produces huge globs of burning metal rather than sparks.

I would like to get ahold of cerium and determine whether the pure metal can spark significantly.

IrC - 17-4-2014 at 13:54

I never disputed the variables in proportions, merely the sloppy way the creation of mischmetal was stated. I know as I have several pounds of mischmetal, also of Ce, La, Nd, Eu, and most other Lanthanides. Except Tm, Tb, Lu, only tens of grams each of those. Expensive. All actually except for the unobtainable Pm. I know what they all look like, act like, and so on. They look like the metals they are not rocks dug out of the ground as was implied by the wording I was complaining about. By the way do not hacksaw Ce, once it starts burning not easy to put out. I do have some nice oxides though. Mischmetal you can hacksaw but do it where you will not be setting your lab on fire as the sparks are thick. I also have lighter flint metal and the composition is not identical to my ingots of mischmetal. You can lay cleanly cut flint metal on a table for months and it does not oxidize all that much. However mischmetal does. Best to keep it well sealed in plastic or under oil. It degrades very slowly but I always have various oxide powders of differing colors when I unwrap a bar of mischmetal. Actually chemically separating the oxides should be one way to find percentages. While I have no assay on my mischmetal I can say I see no irreducible transition oxides left after long oxidation of slices of the ingots which has lead me to believe mischmetal is used to make flint metal but I do not think flint metal is exclusively raw mischmetal. I have long thought the Fe and Mg oxides were combined with mischmetal to create flint metal but am not positive. Just guessing from toying with large quantities of each over years.

Subcomputer - 17-4-2014 at 19:03

I definitely could have said it better, but my main point was that there is no defined, nor way to predict the composition of mischmetal without having your specific piece tested. Are they processing a monazite or bastnäsite load, which RE did that load lean toward, are they set up to pull out neodymium, was neodymium judged economically worth pulling out that day, etc. Plus the question of if you're getting "true" cheap (from the original source...) mischmetal end product, or "purified" RE-only ingots ready for separation.

IrC - 17-4-2014 at 20:39

I agree with that. I have several ingots left and I have no idea what an assay would show. Lots of green, yellow, and white powder when I unwrap one mostly because I am too lazy to can them in oil and bought them around 11 years ago. I just have them wrapped in plastic. Seem to be very high in Ce and La percentage, would be nice to have received an assay sheet with them but the price was too good to pass on to let that get in the way of the purchase. I just bought them with the thought in mind of separation, until I studied the subject enough to realize that would be hard. Not a problem if they are low in Nd though as I have a 2.25 pound ingot of Nd in a paint can of mineral oil. Keeps well even after a decade since I only see a slight swirl of color in the oil from the trace of powdered oxide.

Dan Vizine - 18-4-2014 at 16:18

Thanks, B&F.

Dan: I hope to be one of them, 'shortly'.

BF: I expect to be a customer.

elementcollector1 - 18-4-2014 at 18:42

Kind of a cross-thread question, but here is as relevant as the other threads. Is there some type of valve that could be used during vacuum (e.g. purge the reaction container, and close the valve so it stays at low pressure, and then open it again when the reaction is finished)?

blogfast25 - 19-4-2014 at 11:55

Is there some type of valve that could be used during vacuum (e.g. purge the reaction container, and close the valve so it stays at low pressure, and then open it again when the reaction is finished)?

If you have reaction going on with production of volatiles, your vacuum will always suffer, hence the need to keep pumping.

elementcollector1 - 19-4-2014 at 12:05

If you have reaction going on with production of volatiles, your vacuum will always suffer, hence the need to keep pumping.

If that is the case, how do I prevent volatile products from entering the vacuum system (and presumably destroying it from the inside out)?

Chemosynthesis - 19-4-2014 at 13:21

If that is the case, how do I prevent volatile products from entering the vacuum system (and presumably destroying it from the inside out)?

I would use at least two vacuum traps in that case. You can try to run with dry ice to condense fumes. I've seen aqueous ethylene glycol used as the liquid in these types of traps due to the solvent effects on fumes, and the formation of a cold bath. Additionally, it's a high boiling point, non-volatile solvent, so less of it would get into your pump than acetone, EtOH, i-PrOH, etc.

blogfast25 - 21-4-2014 at 05:46

If that is the case, how do I prevent volatile products from entering the vacuum system (and presumably destroying it from the inside out)?

Depends how volatile they are. In Dan's preparation of Cs the condenser he uses appears to be enough to protect the vacuum pump, if I recall well.

Volatiles needn't be detrimental to the pump either: it depends what they are. If you really need to eliminate them, cold traps are probably best, as the previous poster indicated.

elementcollector1 - 21-4-2014 at 09:21

Sounds good. What I was hoping to do was build an "all-purpose" steel reactor that can either be connected to a condenser for volatile products (Cs, etc.), or simply be capped off for sublimation or non-volatile products (As; Nd, La, Ce, etc.). This would have had a vacuum takeoff *before* the condenser outlet.

blogfast25 - 21-4-2014 at 09:25

This would have had a vacuum takeoff *before* the condenser outlet.

Unless I understand your idea wrongly, that would mean sucking Cs or volatiles into the pump. The condenser should be between the reactor and the pump. The pump needs to pump constantly to maintain the vacuum required.

elementcollector1 - 21-4-2014 at 09:29

Yeah... But then how would sublimation under vacuum work? No matter what you did (short of putting some insanely long length of tubing to the vacuum takeoff, so that everything condenses before it reaches the pump), you would end up having a direct line from the gaseous products to the pump.

Perhaps I should just use the distillation setup for those reactions as well...

Chemosynthesis - 21-4-2014 at 09:37

Yeah... But then how would sublimation under vacuum work? No matter what you did (short of putting some insanely long length of tubing to the vacuum takeoff, so that everything condenses before it reaches the pump), you would end up having a direct line from the gaseous products to the pump.

You usually use a cold finger. That, coupled with a vacuum trap or two should essentially prevent volatiles from entering the pump in sufficient concentrations per time to cause issue.

elementcollector1 - 21-4-2014 at 10:35

Don't have a cold finger on me, but I do, in fact, have a vacuum trap handy. Another thought - how does one link the vacuum pump and the system without flexible tubing?

Back on topic, I guess I'll suck it up and get some nitric acid.

blogfast25 - 22-4-2014 at 12:59

Yeah... But then how would sublimation under vacuum work?

Trust me, condensing something with such a high ambient BP is not a problem under vacuum: the condenser surface temperature is still much lower than the near vacuum BP.

[Edited on 22-4-2014 by blogfast25]

Brain&Force - 23-4-2014 at 16:27

I'm still wondering if fluorescence can be used in the solid or liquid states to track the presence of certain lanthanides in mixtures. In the terbium thread, I've mentioned that ferric ions quench the fluorescence of terbium (though this appears to be due to conflicting absorption and emission bands).

Does anyone know (or at least have any ideas) as to why dissolved terbium compounds do not fluoresce in solution?

The positive effects of scandium on aluminum alloys were discovered in the 1970s, and its use in such alloys remains its only major application.-- Wiki

You could probably expect to see this in applications where cost is secondary, military or not.--Me

A few % Sc in Al is all that is needed. You get a gun light as aluminum but strong as steel. As I noted before, verry expensive. These guns set records*. In bicycles they allowed the ultimate in weight reduction. I guess it maybe didn't catch on in bikes as I never hear about it, usually Ti/Al is the thing I believe. Probably too pricey.

*not accuracy

[Edited on 15-4-2014 by Dan Vizine]

The problem with these guns is that they have WAY too much recoil - I've read this in several places.

Chemosynthesis - 24-4-2014 at 08:01

The problem with these guns is that they have WAY too much recoil - I've read this in several places.

The earlier ones actually cracked frames due to the recoil sheer forces and metallurgical missteps. I'm of the opinion this decreased sales initially.

Dan Vizine - 27-4-2014 at 13:53

If that is the case, how do I prevent volatile products from entering the vacuum system (and presumably destroying it from the inside out)?

In my case, with Cs, the volatiles were primarily non-corrosive gasses and no trap was needed. This represents one of the most vexing things for a basement lab to do...to simply protect your rotary vacuum pump from nasty volatiles. And this is because of only one reason, you need a supply of dry ice or LN2. For most of us this is inconvenient (I have to drive into South Buffalo, over 12 or 13 miles, to get dry ice) or impossible.

One previous post confused me...about getting acetone or 2-PrOH vapors into the pump because of cold traps. The dry ice/ acetone surrounds the outside of the trap. None of it gets into the pump. I favor an alcohol for this, isopropanol or ethanol.

[Edited on 27-4-2014 by Dan Vizine]

Dan Vizine - 27-4-2014 at 14:08

Don't have a cold finger on me, but I do, in fact, have a vacuum trap handy. Another thought - how does one link the vacuum pump and the system without flexible tubing?

Copper lines are good if you watch what you pump through them. You still need a small length of flexible tubing to transition to the glassware. I have no clue where you are, but Home Depot, Lowe's and most hardware stores carry rubber and plastic tubing. The vinyl tubing is cheaper, less durable and can be used with thinner walls than the rubber tubing requires. It is less collapsible.

Chemosynthesis - 27-4-2014 at 14:14

One previous post confused me...about getting acetone or 2-PrOH vapors into the pump because of cold traps. The dry ice/ acetone surrounds the outside of the trap. None of it gets into the pump. I favor an alcohol for this, isopropanol or ethanol.

I was thinking of dry vacuum pumps. I'm not very familiar with them, but I am under the impression they are open to solvent fumes, potentially even from traps or open solvent containers outside of a fume hood, since they lack an oil seal or gas ballast, but I could be mistaken.

Dan Vizine - 27-4-2014 at 14:39

Quote: Originally posted by Chemosynthesis

Do you mean the modern laboratory style? Those pumps (often scroll pumps) will handle nasty stuff as they have Teflon parts in the vacuum train. They are great for many things, although expensive. They don't achieve comparable ultimate vacuums vs. oil filled pumps, but that wasn't what they were designed for.

Chemosynthesis - 27-4-2014 at 15:49

Interesting. I'm actually not very sure what I mean, now that I think of it. Is dry vacuum synonymous with the diaphragm pumps I see with rotovaps?
http://www.sigmaaldrich.com/analytical-chromatography/analyt...

Most vacuum pumps I've ever had to deal with were conceptual black boxes to me. They either had some kind of port in the hood, or a plastic encased switch you press. Whenever I asked people about them, I got the run-around, or strange stories about pump explosions. I know I've had to use at least two types of vacuum pump: one was recirculating, and I assume was a peristaltic pump in a grey enclosed tub. The other is standardized through the lab and attached to every rotovap (all Buchi, that I've seen), and then the mysterious high vac came from a barb in one of the hoods.

IrC - 27-4-2014 at 22:11