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ave369
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Overlooked Ferrates
I have an interest in the ferrate (VI) salts, and I've found it very hard to find useful information about ferrate salts other than potassium, sodium
and barium.
There is almost nothing to be found in the Internet about calcium ferrate, lithium ferrate, magnesium ferrate. Are they unable to be synthesized? Is
there any ferrate solubility table?
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hyfalcon
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Read, read, read.
https://www.google.com/?tbm=pts&gws_rd=ssl#tbm=pts&q...
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BromicAcid
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Sometimes it's amazing how little information is on the internet for a given subject. While on the other hand it would not shock me in the slightest
if there where whole books written previously on ferrates.
Oh, and a quick amazon search says there is at least one:
Ferrates: Synthesis, Properties, and Applications in Water and Wastewater Treatment (ACS Symposium Series) Hardcover – July 25, 2008
Did you check the literature in the SM library? There is likely entries in Mellor's for at least some of these. But as far as I know ferrates do not
need a large cation to stabilize them so any metal cation (in a high oxidation state so it itself is not subject to the oxidation) could be used with
the ferrate. So there is nothing on in the way (at least on the surface) to making calcium, lithium, magnesium ferrate etc. If you could make the
barium then you would be able to easily do a displacement with the sulfate salt of some of those to make your target.
As for the ferrate solubility table, it's hard to find solubility tables for some common salts, let alone something as exotic as ferrates, you may be
out of luck.
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aga
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Are you looking to achieve something specific with Ferrate (VI) salts or is it for general interest ?
Edit:
Ah. I saw your post in an old thread relating to water purification.
From a Survivalist's point of view, surely the biological contaminants can be easily removed by heat.
In extreme conditions, perhaps the removal of heavy metals, radioactivity etc would be more useful ?
[Edited on 9-7-2015 by aga]
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blogfast25
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It's very difficult (virtually impossible) to prepare solid ferrates, they're far too unstable. See this preparation where the solid obtained
contained only barely 42 w% of the target Na2FeO4:
http://pubs.acs.org/doi/abs/10.1021/ja01155a545
One could look into preparing ferrates by anhydrous route but with water the resulting ferrate invariably oxidises water! Yield is therefore by
definition small.
[Edited on 9-7-2015 by blogfast25]
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chemister2015
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http://pubs.acs.org/action/doSearch?text1=ferrates%28VI%29&a...
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ave369
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Quote: Originally posted by blogfast25  |
One could look into preparing ferrates by anhydrous route but with water the resulting ferrate invariably oxidises water! Yield is therefore by
definition small.
[Edited on 9-7-2015 by blogfast25] |
My idee fixe is using solvents other than water. Specifically, solvents that can be cooled to very low temperatures and remain liquid. The idea is
that low temperatures will make the ferrates stable and more easily isolable.
My current idea is electrolyzing a very cold KOH-EtOH solution. As far as I know, ferrates do not react with very cold EtOH and aren't soluble in it
at all. And if you replace KOH with NaOH, you will get an easy way to isolate solid sodium ferrate.
[Edited on 10-7-2015 by ave369]
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AJKOER
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Per this source, "Hydrogen Generation from Alkaline Solutions of Methanol and Ethanol by Electrolysis" by Islay Ulusoy, I suspect you will convert
your KOH into K2CO3 and generate H2 at unusually low electric energy consumption as compared to the standard electrolysis of water.
Link: http://www.academia.edu/534836/Hydrogen_Generation_from_Alka... and see also http://www.evworld.com/news.cfm?newsid=14290 and http://www.sciencedirect.com/science/article/pii/S0378775306...
My speculation as to the underlying radical chemistry with methanol containing water (and similarly with ethanol) at low voltage:
CH3OH ---electrolysis→ CH3 • + HO•
(this source acknowledges the formation of the Methyl radical under electrolysis: http://pubs.acs.org/doi/abs/10.1021/ja01529a021?journalCode=... and see also http://www.ncbi.nlm.nih.gov/pubmed/20580488 and http://journals.plos.org/plosone/article?id=10.1371/journal.... with respect to possible hydroxyl radical and H2O2 formation via electrolysis):
CH3 • + H2O → CH3OH + 1/2 H2 (g)
where the active Methyl radical attacks water (see https://en.m.wikipedia.org/wiki/Methyl_radical ), which may explain the low energy formation of hydrogen as compared to the higher voltage
required to liberate H2 directly from H2O.
HO• + HO• → H2O2
and finally:
CH3OH + 3 H2O2 → CO2 + 5 H2O
2 KOH + CO2 → K2CO3 + H2O
Note, if any O2 was directly formed, I would expect:
CH3• + O2 → CH3O2•
CH3O2• + O2 → HCHO + HO2•
HO2• + HO2• → H2O2 +O2 (reference: http://www2.nau.edu/~doetqp-p/courses/env440/env440_2/lectur... )
that is, a distinct odor of Formaldehyde would be detected. Also, the hydrogen gas created may not be pure due to the formation of a small amount of
Ethane via:
CH3• + CH3• → C2H6
The overall number of products formed is undoubtedly more extensive, but if my take on the chemistry approaches correct, perhaps I have contributed to
a better understanding of the underlying processes.
---------------------------------------------
Note, with respect to the electroIysis, I would also expect, per Wikipedia on the Methyl radical:
"Methyl is very corrosive to metals, forming methylated metal compounds:
M + n CH3• → M(CH3)n "
that an Aluminum electrode in CH3OH, especially containing water, would quickly be subject to corrosion.
Caution: the net reaction upon the electrolysis of say just 404 cc of pure methanol contained in an additional body of water could potentially produce
10 moles of CO2 (or some 224 liters) and 5 moles of hydrogen (112 liters) presenting both a suffocation and a fire/explosion hazard. Fumes from other
reaction products are likely toxic and carcogenic as well.
[Edited on 10-7-2015 by AJKOER]
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DFliyerz
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I have been very interested in ferrates this past week, and have been doing some experiments in preparing barium ferrate, which is a stable insoluble
ferrate salt. I'm linking two videos, one on methods of preparing ferrate, and one on preparing barium ferrate/the properties of ferrates.
https://www.youtube.com/watch?v=5u8LOfTrO6w
https://www.youtube.com/watch?v=2L906yG0-14
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The Volatile Chemist
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Interesting, as I have a small quantity of soluble Barium salt. Could be of interest. Aren't there a lot of interesting mixed-oxidation oxides of iron
that are interesting, at least to a degree?
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DFliyerz
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I have some observations on preparing sodium ferrate by the first method outlined in the first video I linked, and couldn't think of any other place
to report them, so here it goes:
When filtering the solution through fiberglass, I've found that the filtrate starts green and eventually transitions to the violet/amethyst of sodium
ferrate, but the previous filtrate stays green. I'm not sure what's causing this, but an old paper I found suggests the formation of sodium manganate.
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ChemPlayer_
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DFliyers, thanks for sharing; great videos!
I'd read that using stronger solutions of iron (III) chloride and freshly made hypochlorite it was actually possible to obtain dark purple crystals of
the alkali ferrate salts on cooling the reaction mixture. Did you try this or have any luck with obtaining solid salts?
They're interesting compounds and definitely going on my experimentation list.
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AJKOER
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Actually, just found this by accident, "A New Way to Prepare Ferrate Solutions by Microwave Assisted Hypochlorite-Oxidation Method". Per the abstract,
to quote:
"In this article, a new way to prepare ferrate solution was proposed by combining microwave irradiation and hypochlorite-oxidation method. It was
demonstrated that the reactivity speed can be improved as high as 30 times compared to the single hypochlorite -oxidation method."
To repeat, a 30 fold reaction speed bump!
My take is that apparently, free radicals, which can be formed via microwave irradition, are likely very instrumental in ferrate creation.
Link: http://www.scientific.net/AMR.554-556.632
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The Volatile Chemist
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Where did you read this?
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aga
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Solubility at various temperatures is something you can determine experimentally, although there is probably a mathematical route working that out.
Thermodynamics, Gibs's/Higgs's and Kinetics are involved in working out if stuff will react, and at what rate in a given temperature/situation.
It would be of IMMENSE interest (at least to me) if someone could give the workings out of an example.
E.g. NaOH and HCl readily react at room temperature at fairly low concentrations.
At what temperature/relative concentrations will they Not react (as in an imperceptible rate) ?
(0 of everything obviously would be a case, yet significantly less interesting)
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AJKOER
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More details available for a fee at D. S. Li, X. L. Chen, "A New Way to Prepare Ferrate Solutions by Microwave Assisted Hypochlorite-Oxidation
Method", Advanced Materials Research, Vols. 554-556, pp. 632-635, Jul. 2012.
And no, I have not purchased the article.
On free radical formation, if that your question, speaking generally, they can be created via irradition including a radioactive source, plasma
pulses, microwaves, uv light (atmospheric chemistry is mosty radical based), high temperatures (like in the science of combustion of gases),
electrolysis (pollution abatement technique to breakdown nasty organics via methyl, actyl radicals,..)....
The augmenting role of radicals in the formation of ferrates is my speculation as a microwave heating of aqueous mixtures differs not significantly
otherwise, in my opinion, from normal heating by contact with a burning fossil fuel with the noted exceptions of rapid heating, more uniform heating
and bulk heating effects. As such, assuming a non-thermal effect, a likely guess on my part is a radical based increase in reactivity, which is
characteristic of some radicals themselves (and how they can be used to boost chlorate formation, for example, in one of my more obtuse SM threads,
see http://www.sciencemadness.org/talk/viewthread.php?tid=34429#...).
I should also note with respect to ferrous and ferric ions there is a body of work referred to as Fenton chemistry, Electro-Fenton and Photo-Fenton
chemistry involving the formation of the highly reactive hydroxyl radical (as some background, see for example, "Fundamental Mechanistic Studies of
the Photo-Fenton Reaction for the Degradation of Organic Pollutants" at https://www.google.com/url?sa=t&source=web&rct=j&... ). In the case of Photo-Fenton chemistry, the precise pH at which the OH. radical
is efficiently produced appears to be a function of the absorbance ability of the particular Iron species existing at that pH. In the case of ferrate
formation, different Ferric species are likely present at higher pHs which may contribute to a similar ferrate promoting radical based reaction.
The cited article above may only state factually the performance jump, and be clueless (or perhaps unwiling to speculate), as to the underlying (I
would say possibly radical based) chemistry involved.
[Edited on 17-7-2015 by AJKOER]
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blogfast25
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| Quote: Originally posted by AJKOER | Actually, just found this by accident, "A New Way to Prepare Ferrate Solutions by Microwave Assisted Hypochlorite-Oxidation Method". Per the abstract,
to quote:
"In this article, a new way to prepare ferrate solution was proposed by combining microwave irradiation and hypochlorite-oxidation method. It was
demonstrated that the reactivity speed can be improved as high as 30 times compared to the single hypochlorite -oxidation method."
To repeat, a 30 fold reaction speed bump!
My take is that apparently, free radicals, which can be formed via microwave irradition, are likely very instrumental in ferrate creation.
Link: http://www.scientific.net/AMR.554-556.632 |
All you've got is an abstract, 1 page and a nonsensical sentence: "compared to the single hypochlorite -oxidation method".
But we all know you're pleased with a dead mouse as long as it's got the word 'hypochlorite' in it.
Pfffff...
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AJKOER
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Here is a Patent (please see "Method for preparing alkali metal ferrates and novel alkali metal ferrate granules", US 20050053543 A1), to quote the
abstract:
"The invention concerns a method for preparing an alkali metal ferrate, which comprises the following steps: (i) preparing a reaction mixture
comprising at least an iron salt, at least an alkali or alkaline-earth metal hypochlorite and an alkali metal hydroxide; (ii) heating the mixture
prepared at step (i) to a temperature ranging between 45 and 75° C., so as to form the alkali metal ferrate; (iii) recuperating the alkali metal
ferrate formed at step (ii). The invention also concerns novel alkali metal ferrates."
Link: http://www.google.com/patents/US20050053543 that discusses the hypochlorite method among other things.
So, replace "heat" with "heat in a microwave", and yield may improve. In fact, the author of this Patent cites said use, to quote:
"8. Process according to claim 1, characterized in that said mixture is heated using infrared."
[Edited on 17-7-2015 by AJKOER]
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blogfast25
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Sigh. The cations here are spectator ions. I can make any solution of any alkali metal ferrate in a beaker on a hot plate.
Re. how microwaves help in the process, please put up or shut up.
You're chasing another mirage, one of your favourite pass times...
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AJKOER
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Blogfast, a reference "Microwave-Assisted Chemistry: Synthetic Applications for Rapid Assembly of Nanomaterials and Organics", to quote:
"Microwave-assisted chemical reactions are now well-established practices in the laboratory setting although some controversy lingers as to how MW
irradiation is able to enhance or influence the outcome of chemical reactions. Much of the discussion has focused on whether the observed effects can,
in all instances, be rationalized by purely thermal Arrhenius-based phenomena (thermal microwave effects), that is, the importance of the rapid
heating and high bulk reaction temperatures that are achievable using MW dielectric heating in sealed reaction vessels, or whether these observations
can be explained by so-called “nonthermal” or “specific microwave” effects."
Link: http://pubs.acs.org/doi/abs/10.1021/ar400309b
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blogfast25
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I.o.w whether microwaves have an effect other than purely thermal remains up for grabs. Good luck to anyone trying to separate the two effects
(assuming there really is a non-thermal effect).
Try and be a little less credulous.
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AJKOER
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Actually Blogfast, here is a tenative explanation as to how yield could be augmented with microwaving (MW):
1. We start by adding NaOH to say aqueous Fe2(SO4)3, forming a nano-suspension of Fe(OH)3. MW is say to be benefical in creating more uniform
particle sizes,...
2. Apparently, Fe(OH)3 is capable of creating hydroxyl radicals on exposure to UV in a manner similar to TiO2 (source: http://pubs.acs.org/doi/abs/10.1021/j100354a021 ).
3. Apparently, TiO2 forms hydroxyl radicals both via UV and MW. Please see http://www.researchgate.net/publication/223007525_Hydroxyl_r... So, let's assume that Fe(OH)3 behaves likewise in this regard.
4. The equilibrium reaction between hydroxyl radicals and hydrogen peroxide (see, for example, https://books.google.com/books?id=rjEgq4Qf69MC&pg=PA296&...
OH. + OH. + M = H2O2 (where M is a mass)
5. The reaction of H2O2 in the presence of a basic hypochlorite forms nascent oxygen. Please see one of my prior SM's thread and references therein at
http://www.sciencemadness.org/talk/viewthread.php?tid=31729#...
6. The action of any created nascent oxygen could augment the power of the hypochlorite in forming ferrates.
Interestingly, here is an actual historical journal report of the formation of both ferrates and nascent oxygen from the action of Fe(OH)3 on chlorine
bleach over time which likely encompasses uv exposure (see https://books.google.com/books?id=tjIAAAAAMAAJ&pg=PA731&... ).
[Edited on 18-7-2015 by AJKOER]
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blogfast25
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And why would we 'assume' that, huh?
As so often with you, lengthy chains of assumptions designed to make you 'sound interesting'.
Sadly you remain as crashing a bore as ever. Not to mention a prime example of how a little knowledge is a dangerous thing...
But hey, you're in a hole, so keep digging!
[Edited on 17-7-2015 by blogfast25]
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aga
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Personally i like AJ's posts.
Lots of things to click on.
I like yours too, but will not say which i like best 
[Edited on 17-7-2015 by aga]
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blogfast25
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How about a random tinkerwebs surf? Infinite links!
Start here:
https://en.wikipedia.org/wiki/Molten_salt_reactor
... and let the Click-a-Thon begin! 
[Edited on 17-7-2015 by blogfast25]
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