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Texium
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Quote: Originally posted by S.C. Wack  | | So how about finding a similar price for TCCA and recalculating, now that you've proven that permanganate is in fact cheaper. Personally if I was
going to special order something I'd go with the lowest price, esp. if it was to my door. And I'd buy a lot of it if it was useful and stable for
decades. |
I didn’t “prove that permanganate is cheaper:” my final conclusion was that at best it’s
about the same cost as TCCA for chlorine production, so I don’t even know what you’re talking about. My main point from the beginning was that
your statement of what is commonly available OTC is completely backwards. Permanganate is rarely available OTC nowadays. TCCA is available at pool
stores and most hardware stores. Doing the math has led me to conclude that if you can get reasonably priced permanganate, it’s just as cost
effective as TCCA. Congratulations, you’ve changed my mind with this exercise. That being said, I’ve also observed that some pool chemicals go on
deep clearance when they’re out of season, so being able to snag some TCCA or possibly NaDCC at a ridiculously low price isn’t unheard of. Bottom
line is, either of these chemicals are good for chlorine production. Which one is best depends on what is locally available for you.
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Fantasma4500
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okay so, what about persulfate? it forms chlorine on contact with table salt or in solutions of chloride
1kg sodium persulfate 13 euros
Na2S2O8 + 2 NaCl = Cl2 + 2 Na2SO4
1000g + 491g = 297g(4.2M) + 1193g
https://www.ebay.de/itm/144018689254?hash=item21882ecce6:g:K...
2 KMnO4 + 16 HCl = 2 KCl + 2 MnCl2 + 8 H2O + 5 Cl2
1000g KMnO4 yields 1121g Cl2- with 1845g HCl .. 6.15L HCl 30%? now we wanna also factor the HCl into this equation. seems about 3e/L 30% here
what about TCCA
C3Cl3N3O3 + 3 HCl = 3 Cl2 + C3H3N3O3
1000g + 470g = 915g + 555g
so 1kg TCCA, 1.5L HCl 30%? one quart the HCl required, while it produces only 200g less Cl2. 81.6% of the chlorine that KMnO4- albeit with 4x as much
HCl. it could appear TCCA is infact more compact
so lets say, for 1kg of Cl2 gas you need:
1100g TCCA 14e/kg = 15.4e
890g KMnO4 29e/kg = 26e
3300g NAPS - 13e/kg = 43e
0.89x 6L HCl at 3e/L would give 16e cost for HCl 30% - 5.34L for KMnO4
and 1100g TCCA + 1.65L 30% HCl =5e
NAPS uses table salt, 1kg is 0.5e, 0.25e.
so the corrected price for the 3, for 1kg Cl2 gas comes out to
TCCA: 20.4e
KMnO4: 42e
NAPS: 43.25e
KMnO4 i would agree is not readily available and is even a watched chemical, NAPS is more under the radar. however KMnO4 does yield KCl and MnCl2 but
manganese can also be toxic. the real bonus with KMnO4 is how colorful it is. i went off with european ebay price for TCCA. infact i cant find
anything but 150g KMnO4 from thailand priced at 45e. KMnO4 MAY however, eventually, be possible for the amateur chemist to make at home, once i
progress into cracking that one. i believe cyanide may be made from cyanuric acid somehow, but i couldnt find my way around last time i looked into
it, so TCCA does also yield a somewhat useful product.
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SWIM
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| Quote: Originally posted by unionised |
It has.
Removal of water, as the vapour from a frozen material is (1) what the plan here was and (2) how a freeze dryer works.
Whether you remove it with a vacuum pump or a desiccant isn't a huge difference.
Obviously the pump works better but, if your idea that cold stuff won't evaporate were true, then freeze dryers wouldn't work.
They do.
It isn't. |
Freeze dryers don't evaporate things.
They sublimate things.
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S.C. Wack
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I'm guessing that you don't use desiccators much? I do; using lime, sulfuric acid, calcium chloride. In fact I'll be posting in another thread about
an experiment with lime that's already been going on for a week. I posted what I did because I'm aware of their limitations.
If one adds a kg of desiccant, with 100 ml of water on a dinner plate on a short pedestal on the shelf, then yes a substantial amount of water will be
transferred at room temperature...after 3 days...but it would be unsurprising if vacuum obviously outperformed that even in such unrealistic use. I
can't imagine that doing it in a freezer would go well at all.
[Edited on 15-3-2022 by S.C. Wack]
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Sulaiman
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on the topic of cost effective chlorine generation ;
it does not matter 
availability, disposability and safety are the important parameters - to me
at amateur level there is no need for industrial volumes or cost effectiveness.
CAUTION : Hobby Chemist, not Professional or even Amateur
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Tsjerk
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Enthalpy of sublimation is a bit higher than enthalpy of evaporation (50 kJ/mol against 40 kJ/mol). But the surface area at which sublimation can
occur quickly becomes much larger during sublimation as pores and cavities are formed. Surely sublimation occurs slower because of the lower
temperature, but the temperature needs to be low here anyway.
I can imagine freeze drying to be fast, I even noticed first hand it can be fast. A vail with a couple of milliliters goes in an hour at -18 at
mediocre vacuum. Larger samples take longer, but when left over night tens of milliliters are gone. But who cares? You have to cool the samples
anyway, so whether it is in a freezer with or without vacuum doesn't really matter.
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unionised
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SRSLY?
You don't realise that sublimation is evaporation?
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unionised
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I guess you don't use vacuum desiccators much.
Perhaps you should.
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SWIM
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Not according to most sources who don't happen to be you.
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MadHatter
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Potassium Permanganate
Texium, that's an excellent price for KMnO4. I used to buy from Sears, retail
store, for well over $30 for 5 LBS. On the plus side, it was truly OTC. As for
NaOCl, just my opinion, there's no need to have it in a "solid" form. It works
fine just the way it is.
From opening of NCIS New Orleans - It goes a BOOM ! BOOM ! BOOM ! MUHAHAHAHAHAHAHA !
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S.C. Wack
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Who said anything about using vacuum desiccators?
The truth/fact (what I deal in) is, my desiccator is the vacuum kind, but I have little desire to run one of my pumps constantly (or buy something
that will measure vacuum and activate the pump at a set pressure) or set up a drying train to keep water out of the pump oil (the recirculating
aspirator pump water gets warm before long). When small amounts of things to be dried are used, it creates its own vacuum.
If one wants to try an experiment in the *actual spirit* of the original suggestion, they could weigh some ice cubes and put them in a cup in a bag
containing silica gel in the freezer and weigh the cup from time to time. I'd be interested to hear the results.
Needless to say, it would be unsurprising if the verdict was that it would be wiser not to freeze the hypochlorite.
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Fantasma4500
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sublimation is change of state but we typically use it in these forums to explain that it goes from solid to gas, such as iodine- as to explain that
the sublimation is abnormal. if that makes sense.
but per textbook you would be right as liquid to solid, solid to gas, gas to liquid etc any change of state is considered sublimation- no im in the
wrong here. sublimation outlines per definition change of either liquid or solid into gas
sublimation, in physics, conversion of a substance from the solid to the gaseous state without its becoming liquid. An example is the vaporization of
frozen carbon dioxide (dry ice) at ordinary atmospheric pressure and temperature. The phenomenon is the result of vapour pressure and temperature
relationships.
but we still- typically use it just to explain solid to gas as evaporation is the term we use for liquid to gas.
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