Sciencemadness Discussion Board

chlorates from calcium hypochlorite

bold_ing - 11-6-2019 at 16:29

hello !

i have tried before to make potassium chlorate from bleach and it worked but the yeild and cost didn't satisfy me
i don't have a direct source of potassium chlorate nor can i get electrodes for a cell , but what i do have is a wotta lotta cheap as dirt calcium hypochlorite 65%
so any ideas on how can i proceed to convert it into beautiful crystals of KCLO3?with the best possible efficiency ?

j_sum1 - 11-6-2019 at 17:39

What is your potassium source?

bold_ing - 11-6-2019 at 17:48

potassium chloride , I make it from potassium sulfate and calcium chloride , I'm wondering if just putting the calcium hypochlorite in a bunch f water and boiling it for a couple of hourse would work but the decmop temp is around 178C

j_sum1 - 11-6-2019 at 22:49

Why not use potassium sulfate and the same precipitation of calcium sulfate? Leaving you with potassium hypochlorite in solution?

bold_ing - 12-6-2019 at 04:10

It's hard to filter what is basically plaster lf paris, a lot of the potassium hypochlorite would be left behind and that also means using a lot of water.
It's viable bit since I have already prepared pounds of KCL ill use that

Prepic - 12-6-2019 at 07:40

Well hopefully you have read through this first http://www.sciencemadness.org/talk/viewthread.php?tid=10727

I've actually tried "Wouters method" and it provided me with low yeild. (although that could easily be my fault)

Since then I thought of repeating it but first by adding sodium bicarbonate to precipitate calcium carbonate, zinc carbonate,cooper carbonate and aluminum hydroxide and leave behind sodium sulphates and sodium hypochlorite followed by filtration(CaSO4, ZnSO4, CuSO4, Al2(SO4)3 are impurities according to the MSDS of my calcium hypochlorite )

From here I'd imagine boiling it for some time and then throwing in KCl should yield some potassium chlorate. I believe the disproportionation of soidum hypochlorite is more favorable than with calcium hypochlorite.

bold_ing - 12-6-2019 at 11:03

Quote: Originally posted by Prepic  
Well hopefully you have read through this first http://www.sciencemadness.org/talk/viewthread.php?tid=10727

I've actually tried "Wouters method" and it provided me with low yeild. (although that could easily be my fault)

Since then I thought of repeating it but first by adding sodium bicarbonate to precipitate calcium carbonate, zinc carbonate,cooper carbonate and aluminum hydroxide and leave behind sodium sulphates and sodium hypochlorite followed by filtration(CaSO4, ZnSO4, CuSO4, Al2(SO4)3 are impurities according to the MSDS of my calcium hypochlorite )

From here I'd imagine boiling it for some time and then throwing in KCl should yield some potassium chlorate. I believe the disproportionation of soidum hypochlorite is more favorable than with calcium hypochlorite.

Where did you get the hypochlorite from? I'm guessing in a product premade for laundering or maybe pool chlorinator?
If everything goes well I should be expecting at least 300g KCLO3/KG of 65% calcium hypochlorite, I'll run a few batches and see what I get in terms of yeild

Prepic - 13-6-2019 at 07:15

I used pool chlorinator (68% calcium hypochlorite). 300g/kg would be pretty good. Please do let me know your yields if u get around to doing the experiment(s).

fusso - 13-6-2019 at 07:29

What about making a Cl2 generator using Ca hypochlorite and lead Cl2 into a hot KOH soln?

Prepic - 13-6-2019 at 11:45

Its a cool idea and maybe it could work but how i see it:

3Ca(ClO)2 into 6NaClO
6 NaClO → 4NaCl + 2NaClO3
(3mol Ca(ClO)2 for 2 mol NaClO3 product)

and

3Ca(ClO)2 to generate 3Cl2
6NaOH+3Cl2→5NaCl +NaClO3+3H2O
(3mol Ca(ClO)2 for 1 mol NaClO3 product)

So far better potential yield via the disproportionation reaction. Also, you will be left with so much chlorides it might be very hard to purify.

j_sum1 - 13-6-2019 at 15:46

Quote: Originally posted by fusso  
What about making a Cl2 generator using Ca hypochlorite and lead Cl2 into a hot KOH soln?

Not hot. Chilled.

fusso - 13-6-2019 at 19:50

Quote: Originally posted by j_sum1  
Quote: Originally posted by fusso  
What about making a Cl2 generator using Ca hypochlorite and lead Cl2 into a hot KOH soln?

Not hot. Chilled.
But he wants chlorate so isn't hot the way to go?

j_sum1 - 13-6-2019 at 22:06

70°C is optimum for electrolysis.
But if you are bubbling a gas through then that is a different process. You want the equilibrium to favour dissolution of the gas so the reaction can take place. If you think about it, if you heat a chlorate solution you liberate Cl2 gas. Conversely, cooling it will retain the gas. This is on top of the fact that cooler temperatures increase solubility of gases.

clearly_not_atara - 14-6-2019 at 12:10

S.C. Wack's post about the hypochlorite decomposition is very interesting:

http://www.sciencemadness.org/talk/viewthread.php?tid=10727&...

It would appear that, contrary to expectation, alkali is not beneficial in this reaction. In fact it lowers yields and increases the heat required. In fact, the reaction mixture should not be heated, and it is more important to control the pH, so that it is neither too alkaline (inhibits decomposition) nor too acidic (leads to chlorine evolution).

So I'm tempted to suggest experimenting with very weak acids like sodium bicarbonate or sodium sesquicarbonate rather than heating. Caution is essential because excess acidity will lead to evolution of chlorine.

AJKOER - 15-6-2019 at 17:48

I have prepared and tested (like mixed with powdered sugar and ignited) in more than one thread. See if you can get something out of this one http://www.sciencemadness.org/talk/viewthread.php?tid=34429 .
-----------------------------------------------------------

My recent expansion in knowledge suggests to partially acidify aqueous Mg(OCl)2 (or Ca(OCl)2) with CO2, apply mild heat, O2 and sunlight. Both MgCO3 and CaCO3 suspension in sunlight are photocatalyst capable of inducing needed radicals especially, the hydroxyl radical.

A simple alternate path to introduce the hydroxyl radical is periodic low dosing with H2O2 (which decomposes ClO- eventually leading to O2 (which I would keep in the system) but apparently the reaction commences with some .OH creation (see https://www.researchgate.net/publication/230651663_Hydroxyl_... ). Cited reaction (1):

OCl- + H2O2 --> .OCl + .OH + OH- (1)

I may soon try the action of microwaving (MW) on a form of activated carbon (AC) in an acidified hypochlorite in the presence of oxygen. Logic, the action MV on the carbon surface forms zones of excess and deficiency in electrons:

C(surface) + MV = C(+) + e-

O2 + e-(aq) = .O2- (aq) (the superoxide radical anion)

.O2- + HOCl = .OH + O2 + Cl- (see Eq 2 at http://protein.bio.msu.ru/biokhimiya/contents/v78/pdf/bcm_14... )

The superoxide would likely have a longer half-life in the presence of ions of Al, Mg or Ca (see below). One may consider the action of O2 converted to superoxide reacting with hypochlorous acid resulting in the hydroxyl radical precursor as an explanation as to why certain bleaches (like Mg(OCl)2) are claimed to be more sensitive to air exposure leading to decomposition/chlorate formation.

An alternate path to .OH absence O2 may proceed as follows in the presence of solvated electrons:

HOCl + e-(aq) = .OHCl-

The above radical may breakdown depending on pH above or below 5 as follows:

.OHCl- --> .OH + Cl- (pH > 5) (Source: Supplement Table S1 at: http://www.mdpi.com/1420-3049/22/10/1684 and click on Supplement F1 to download)

.OHCl- --> OH- + .Cl (pH <5) (Source: Supplement Table S1)
----------------------------------------------

Mg(OCl)2 can be sourced from mixing common sodium hypochlorite (pool strength is available in grocery stores in more southern states) and Epsom Salt (actually, a very pure MgSO4 hydrate as people take baths in Epsom Salt and could ingest through the skin heavy metals if not pure) is a good start. I recommend freezing out the Na2SO4 as the SO4- ion will scavenge valuable hydroxyl radicals needed for chlorate formation.

My reasons are, in addition to purity, I recall a patent claiming problematic chlorate formation as Mg(OCl)2 is apparently more sensitive than NaOCl in converting to chlorate on warming (like 70 C and not boiling). Also, if you read my thread on how Al3+ complexes with superoxide radical (.O2-) (link: http://www.sciencemadness.org/talk/viewthread.php?tid=96347#...), there is a mention of similar occurrences with Ca and Mg ions in one of the papers. This Al[.O2]2- ion apparent extends the life span of .O2- (created by e- acting on O2), which can reduce transition metals like Fe(3+) to Fe(2+), which is a precursor to fenton production of the hydroxyl radical (.OH), which is an important precursor to ClO3- creation. Carbon produced by accidentally burning vegetables is also a source of radicals especially in a pan (of Al or Fe?) with boiling bleach. In fact, there is a report in Bretherick on an explosion occurring by someone trying to clean a pot with burnt vegetables on boiling with NaOCl, and forgetting it was on the stove! An accidentally revealed chlorate route!

Burnt food activated carbon has even more uses. See my thread http://www.sciencemadness.org/talk/viewthread.php?tid=151055 especially for a fast track to CuSO4, which in place of MgSO4 would create Cu(OCl)2 upon freezing out the Na2SO4 hydrate after mixing CuSO4 with NaOCl.

An experiment I would consider with Cu(OCl)2 is to acidify (perhaps a small amount of acetic or critic acid), insert a copper tube, pump in air while warming to 70 C. Logic:

Cu + Cu(ll) = 2 Cu(l)

H+ + OCl- --> HOCl

Cu(l) + HOCl = Cu(ll) + .OH + Cl-

O2 + Cu(l) = Cu(ll) + .O2-

.O2- + HOCl = .OH + O2 + Cl-

.O2- + Cu(ll) = O2 + Cu(l)

......

Little mentioned about Copper hypochlorite as it is unstable, but even if it leads easily to chlorate, having a trace of copper ion, probably makes it an unsafe product!

Here is some more recent literature than Mellor: https://pubs.acs.org/doi/abs/10.1021/ie00026a010 .

[Edited on 17-6-2019 by AJKOER]

bold_ing - 16-6-2019 at 18:20

The threads are pretty good , but going the chlorine way would be better-ish with TCCA and HCl but idk if I can handle running a Cl generator for long periods of time unsupervised,maybe im a few weeks when I have more time on my hands
And the mildly acidified disproportionation is definitely intresting, I'll try a couple small batches and see what I get.

AJKOER - 17-6-2019 at 06:44

Quote: Originally posted by bold_ing  
The threads are pretty good , but going the chlorine way would be better-ish with TCCA and HCl but idk if I can handle running a Cl generator for long periods of time unsupervised,maybe im a few weeks when I have more time on my hands
And the mildly acidified disproportionation is definitely intresting, I'll try a couple small batches and see what I get.


On the mildly acidified disproportionation path, it is important to have some hydroxyl radical presence, otherwise a very poor yield. The .OH sourcing is the major place for innovation, whether via electrolysis, or from a photocatalytic salt (like MgO, TiO2,...), or the action of a microwave on activated carbon, or perhaps a fenton-type reactions based on small amounts of Fe(ll), Cu(l),.... , or perhaps even formed superoxide radical, working on HOCl (and unfortunately, after all the HOCl is consumed, available HClO3 is attacked, so harvest product (add KCl and freeze out the KClO3 followed by adding more acidified bleach thereby maintaining a HOCl presence). To expand on my last point, think of the so called 'bleach battery', which involves an electrochemical reaction where one reagent is consumed entirely, and then goes on to the next reagent capable of producing an electrical charge (but now at a lower level, but higher than other possible candidates) for the battery cell, etc.

[Edited on 17-6-2019 by AJKOER]