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blogfast25
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@not_important:
Oh, that second *.pdf is great too. All this info should keep me sweet for days!
I don't have a single nickel compound at hand right now, what is it supposed to do? Our coins don't contain any, IIRW. But boiling the 200 mL of
emulsion with 200 mL commercial bleach for 10 minutes caused clear separation with the hydrophobic phase sitting neatly on top of the clear (well,
very slightly turbid) watery phase. Separating completely will be easy and done tonight.
But I'm weary to reduce the watery phase down to almost dryness at this point. Will this not Diels-Alder some of the remaining fragile organics into a
carbonised mess? I'm not entirely sure but I seem to have had this problem at the first attempt. One way to get rid of carbonised matter is boiling
with strong alkali of course.
Right now I'm more tempted to thoroughly filter the watery phase, dilute it and eliminate the aluminium at pH = 10 - 11 with strong NaOH. Any
remaining fatty acids should saponify and dissolve.
A second treatment with strong bleach is certainly tempting.
I might just test both routes separately on small quantities...
[Edited on 27-4-2010 by blogfast25]
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not_important
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Nickle salts added to sodium hypochlorite form 'nickle peroxide' which functions as a catalyst for oxidising a number of substrates, not all of which
behave as well or react as completely as without the nickle catalyst.
I'd not worry about Diels-Alder, if for no other reason than ingredients list generally go from major to minor components, those complex organics are
fragrances and only present in small quantities. Diels-Alder isn't noted for carbonising, if you mean dehydration A) most of the H-O-C stuff should
have been oxidised by the hypochlorite, and B) we're talking evaporating as you would on a steam bath, and only until the stuff gets mushy from the
NaCl crystallising out. Bleach is dilute enough that you want to get rid of a goodly percent of the water, which also decomposes most of the
remaining hypochlorite; the result after adding con HCl should salt out the fatty acids and some of the other now oxidised surfactants in the mixture
while holding Al and Zr tied up in MCl4<sup>-</sup> type complexes in the aqueous phase.
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blogfast25
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I mentioned Diels-Alder in relation to a problem that occurred with the first batch: after dissolving the crude Zr(OH)4 in hot 6 M HCl and boiling off
the liquid, I noticed the solution turned noticeably brown near the end. Without absolute evidence I believe this may be due to carbonisation of
organics picked up from the paper filter, upon contact with strong HCl. I have some reason to believe the presence of ZrOCl2 actually aggravates the
problem. Unfortunately the brown stuff doesn't precipitate but it does co-precipitate when re-precipitating the Zr(OH)4 with alkali. I thus have a
batch of Zr(OH)4 (from the first attempt) that is slightly tinged with a beige colour (pure Zr(OH)4 is snow-white) and may be in need of the bleach
treatment.
To avoid this, all filtering of acid solutions is now done after partial neutralisation to pH ≈ 4.
On the watery phase of the second batch, after filtering (it's still very slightly turbid), two treatments have been applied:
Treatment A: eliminating aluminium first.
100 mL of the crude, filtered solution was slightly diluted and alkalised with 5 M NaOH to pH = 11. Upon standing something fairly typical of Zr
happened. After a few hours the clear supernatant started to slightly cloud over. Taking pH again it was near neutral! Presumably the cloudiness was
due to hydrolising aluminate. Due to polymerisation Zr water soluble compounds tend to show some 'sponginess' before settling for a final pH. Here I
adjusted the pH to about 13 - 14 and left to stand overnight. It was hoped that most fatty acids would saponify into water soluble soaps.
The next day the crude Zr(OH)4 was amply washed with dilute NaOH (pH about 10) and ample amounts of hot tap water until the filtrate ran almost
neutral.
The precipitate was then dissolved in 100 mL of hot 6 M HCl but the solution remained very turbid, presumably because of organics. 100 mL of bleach
was added and the solution turned a chlorinish light green-yellow! This solution was then boiled down to about 100 mL and until no chlorine was
detected by smell. It was then re-diluted. The colour remains and some whitish precipitate collected at the bottom. This will now be part-alkalised to
pH ≈ 4 and filtered. The filtrate will be diluted and alkalised with 9 % ammonia to about pH ≈ 7 for re-precipitation of the Zr(OH)4.
Treatment B: without eliminating aluminium first
To 50 mL of the crude, filtered solution was added 50 mL of bleach and a small dash of 6 M HCl. This solution was boiled down to almost dry and then
50 mL of 6 M HCl was added: this caused precipitation as well as the appearance of the chlorinish light green-yellow colour. It could not a priori be
excluded that much of the precipitate might be ZrOCl2 because the latter is poorly soluble in conc. HCl (a preferred method of re-crystallisation,
apparently). So another 50 mL 6 M HCl and water up to about the 200 mL mark was added and the solution brought briefly to the boil again: much of the
precipitate, but not all, seemed to redissolve. This will now be part-alkalised to pH ≈ 4 and filtered. The filtrate, which still contains the
aluminium, will be diluted and alkalised with strong NaOH to about pH ≈ 13 - 14 for re-precipitation of the Zr(OH)4 and elimination of the
aluminium as aluminate.
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blogfast25
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With some delays about half of the ZrOCl2.8H2O has now been crystallised. A first estimate shows that 100 mL of the roll on antiperspirant contains
about 15 g of the zirconylchloride octahydrate. This is only a rough estimate because the yield varied somewhat from batch to batch, Treatment B for
instance giving higher yield than Treatment A (but B is easier with only one precipitation). I'm not sure what those differences are due to but poor
definition of the hydrate may be a cause.
The crystallites were all obtained by dissolving the purified zirconia hydrate (Zr(OH)4.nH2O) in an appropriate amount of 6 M HCl and boiling till
almost dry. When the first onset of crystallisation is observed, near dryness, heat is then switched off and on cooling the compound then crystallises
out. But not all of it may be the octahydrate. Hygroscopicness seems also to vary. I may need to cut the heat slightly earlier.
All crystallites are coloured yellow (to varying degrees) and KSCN shows the culprit is ferri(III)chloride, picked up from the commercial bleach (also
shown by KSCN to contain Fe3+). This may explain also the varying degrees of hygroscopicness.
When all the ZrOCl2 has been collected, I will try and recrystallise the whole lot to try and eliminate the FeCl3. ZrOCl2 can be recrystallised from
strong solutions by adding conc. hydrochloric acid. Alternatively, from strongly acid solutions the ziroconyl chloride can also be precipitated by
adding water (acc. F. Venables).
Unfortunately the sources I have on ZrOCl2 say little about solubility or precise methods of recrystallisation. So a little trial and error will be
required.
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blogfast25
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Although I've still not completely finished with this method of extracting a water soluble Zr source for an OTC material like a roll on antiperspirant
(aerosol antiperspirants contain no Zr, by law, not sure why), I've certainly learned a lot about it...
Firstly, no matter what method it became clear I was always doing something wrong:
1. product yields varied wildly despite very similar treatments,
2. product didn't really behave like ZrOCl2.8H2O is described: there was hydrolysis immediately upon contact with water but product did dissolve
easily when small amounts of HCl were added,
3. each time I tested for Al, some was found.
I began to believe that the product was severely contaminated with Al (as well as with Fe, from the bleach, see bottom of post).
In total about 65 g of variable 'product' had been obtained from 400 mL of antiperspirant. I decided to try another procedure and treated 100 mL of
virgin antiperspirant with 100 mL of commercial bleach and some 50 mL of 6 M HCl. On boiling, the phases separated completely and the hydrophobic
phase sat on top. Decanting and filtering I obtained the clear watery phase (about 200 mL) containing the aluminium zirconium chlorohydrex Gly.
At this point, a word needs to be said about these aluminium zirconium chlorohydrex Gly complexes (AZGly). Here's the datasheet of a typical AZGly, in
this case Zirconal ® AP4G (pdf):
http://www.bk-giulini-pcg.com/dyndata/AP-AP4G.pdf
It's chemical formula is Al4Zr(OH)12Cl4Glyx.nH2O
Note the atomic ratio of Al/Zr = 4 in this case. A bit more research showed that ratio can vary from 2 to 10 for various AZ complexes (which may or
may not contain Glycine, depending on brand)!
It's structure is reminiscent of the real structure of ZrOCl2.8H2O, which does not contrary to popular belief, contain the cation ZrO2+ but far more
likely the polymeric cation [Zr4(OH)8(H2O)16]8+.
Going back to the treatment, the 200 mL of watery phase were then mixed with 100 mL of water in which about 15 g of solid NaOH had been dissolved.
This was stirred strongly and heated in an oven at 150 DC for 2 hours, then filtered and the filtrate checked for Al by neutralising: there was a lot
of precipitate, at least as much as the precipitate on the filter (which I assumed to be Zr(OH)4.nH2O). The precipitate was first amply washed with
boiling 1 M NaOH, then with ample hot tap water, then re-dissolved in 200 mL of 6 M HCl, then re-precipitated from a more dilute solution and at much
lower pH (about 5.5), to avoid occlusion of the NaCl in the zirconia hydrate.
Redissolving again in 6 M HCl and boiling down to about 100 mL, I left the solution to cool and a white precipitate formed: most of the liquid had in
fact turned into a slushy semi-solid. Taking a teaspoon full of sample and adding water, it dissolved effortlessly into a perfectly clear solution,
without any hydrolysis. This looked more like the real thing! I then checked the dissolved sample for Al by adding quite some NaOH, boiling,
filtering and neutralising the filtrate: it still contained Al! Comparing the precipitate on the filter and the precipitated alumina hydrate in the
filtrate, I'd say the 'real thing' contains still at least 10 -30 % Al!
This is a little puzzling: is it possible that the large amount of NaOH wasn't sufficient to convert all the Al into Al(OH)4 (-)? Was the amount of
water too small to dissolve all the aluminate? How then to explain it wasn't washed out with the hot 1 M NaOH?
Another explanation is that when treated with NaOH the AZGly does not split easily into aluminate and zirconium hydrate. I found a reference that
states that to split an AZGly with strong acid (e.g. for titrometric determination of Al or Zr with EDTA) prolonged boiling with acid is necessary.
Could this be true also of the complex in alkaline conditions? Is it possible that the complex tends to lose some Al, thereby being
transformed in another complex, this one with a lower Al/Zr ratio? Either way, it would appear so far that using 'my' method, the 'alkali fusion' may
need to be repeated until all Al has been removed...
Another problem is the contamination with Fe3+, which has proved hard to remove. I hoped firstly that recrystallisation from slightly acid solution
would concentrate the FeCl3 in the mother liquor but the solubilities of ZrOCl2.8H2O and FeCl3 are both quite high. Recrystallisation by adding conc.
HCl (37 %) should be possible but my 20 % doesn't cut it.
Separating out the Fe (after reduction to [+II]) as FeS, Fe(OH)2 or FeCO3 in conditions where Zr doesn't precipitate (pH < 4) isn't possible.
Complexation to ferrocyanate (Fe(CN)6 4-) or ferricyanate (Fe(CN)6 3-) would probably do the trick but I've no cyanides. The ferri thiocyanate
(FeSCN2+) complex isn't stable enough I think.
So, I'm a bit stuck on that.
This afternoon I carried out the first proper attempt at fusing zircon (ZrSiO4) with NaOH according to the Brazilian paper's wet method (see above).
The fusate is now soaking in some water overnight, to loosen it up. Hopefully the fusion will have been successful. Fingers crossed...
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not_important
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Part of the purpose of using hypochlorite is to destroy the glycine, removing issues of the complex changing solubility patterns.
see http://www.biochemj.org/bj/030/0484/0300484.pdf
I suspect that your NaOH concentration may be too low to fully dissolve all the aluminium, the concentration more than the total amount of NaOH. Also
stirring while heating would be better. On the other hand 2 hours seems excessive, I suspect you would do better with a shorter heating and then do a
second extraction with NaOH solution. You should be aware that you may be forming extremely fine precipitate that is getting through your filter
paper.
I see three ways of cleaning up the iron
1) to a nearly neutral solution of the crude product, add some pieces of zinc. Iron should plate out on the zinc, allowing both to be filtered off.
Zn(OH)2 will dissolve in NaOH, like Al(OH)3, and even in strong aqueous ammonia, so it can be leached out of the Zr upon precipitation (or
reprecipitation).
2) Both Al and Fe can be kept in solution as the pH is raised by the presence of acetate. This is done by bringing the pH just to the point that
precipitate starts to form, adding dilute HCl to dissolve that, and adding acetic acid and/or ammonium acetate, then raising the pH in a controlled
fashion. NH3 or Na2CO3 are used in preference to stronger bases. You'll find this in older books on inorganic analysis, it's the sort of thing you'd
want to do after earlier purification.
3) After precipitating the Zr(OH)4 and washing it, stir it into some quite dilute HCl with the hope of leaching out the Fe while dissolving very
little Zr. Or use acetic acid + ammonium acetate, if you can get reasonable strong acetic acid.
Another trick used to remove iron was extraction with ether from HCl solutions, doesn't seem like the best alternative.
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blogfast25
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That's possible but I tested the filtrate for amfoterics by toggling the pH from high to neutral to low and back. Zirconia hydrate does not
re-dissolve at high pH. So any precipitate formed would be in all likelihood hydrated alumina.
As regards removing the Fe, 1) wouldn't work because zirconyl chloride starts precipitating (hydrolising) at about pH = 5. If a neutral solution could
be obtained, I'd have reduced the Fe to +II and precipitated it as Fe(OH)2 (Ks = 4.87 E-17, at pH = 7, [OH-]^2 ≈ E-14).
But I like 2) and 3) which come down to leaching out the Fe3+ and the lowest possible pH without re-dissolving the zirconia hydrate.
Alternatively, avoid Fe altogether, perhaps by using a homemade bleach? Or another strong oxidiser? K2Cr2O7 didn't work and KMnO4 would have the
drawback that the Mn2+ wouldn't be easy to get rid of either...
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not_important
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Consider the H+ ion concentration - there's not too much at pH 5, you'd want to get the pH to the point cloudiness just starts to appear, then
re-acidify a tiny bit. You'll lose some of the zinc to acid, but the iron still should plate out.
Sorry, H2O2 is the best alternative oxidiser, then maybe hot dilute HNO3. Making your own hypochlorite is a bit of a bother, you could do it right in
a mix of the starting goop and aq NaOH and bubble in Cl2, but you may be fighting the Al-Zr hydroxide ppt.
The amount of iron in the bleach has to be small, as the bleach is A) oxidising and B) alkaline, meaning iron should be Fe(III) and drop out as the
low solubility hydroxide-hydrated oxide, which as a rather low Ksp.
The acetate trick should work as it is/was used analytically to separate Zr from Al and Fe.
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blogfast25
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I will attempt to dissolve the contaminated zirconyl chloride into a pH = 5 acetate buffer and plate out the iron with zinc.
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blogfast25
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Applying what had been learned from the previous experience with extracting zirconyl chloride from roll on antiperspirant (ROAP) I applied the
following procedure to get a better idea of zirconyl chloride content:
1. 100 mL ROAP ('Mitchum 48 h - women'), 90 mL of thin commercial bleach and 10 mL of 32 % HCl were mixed and simmered for about 10 min. The phases
separated and the watery phase was filtered off.
2. 20 g of NaOH, dissolved in 100 mL of water were slowly added with intensive stirring to the filtrate and simmered under reflux for 1 hour.
3. The precipitate (very crude ziconia hydrate) was filtered and washed with 500 mL of cold 5 M NaOH, then with copious amounts of boiling water until
pH of the wash water was about 11.
4. The washed precipitate was dissolved in 70 mL of 32 % HCl, with heating to boiling point. The solution was reduced by part refluxed boiling to
about one third of the original 200 mL. This gets rid of a lot of the HCl (thus saving a bit on alkali), without causing hydrolysis of the Zr.
5. The reduced volume was diluted to about 1 L and carefully neutralised to pH = 11 with strong NaOH.
6. The precipitated hydrated zirconia was filtered and washed with copious amounts of boiling water until pH ≈ 8.
7. The washed precipitate was dissolved in 70 mL of 32 % HCl and boiled in (covered) to about 50 mL and allowed to cool and stand overnight. A
semisolid mass of ZrOCl2.8 H2O formed, typically slightly yellow by FeCl3 from the HCl.
8. The crude zirconyl chloride was washed with several small amounts of acetone (distilled from nail polish remover) to remove water and FeCl3, then
given a final rinse with pharma acetone, allowed to dry and dried further for about 15 h in a CaCl2 dessicator.
About 8.15 g of snow white product was thus obtained. Allowing for minor losses, it would appear 100 mL of ROAP contain about 9 g of zirconyl
chloride.
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