| Pages:
1
2 |
Fery
National Hazard
Posts: 990
Registered: 27-8-2019
Location: Czechoslovakia
Member Is Offline
|
|
Hi woelen, thx for clarification. I have 0,9 kg of Ca(OCl)2 from fichema.cz for more than 1 year (maybe 2 years I do not know exactly) in a plastic
bottle and it seems be still the same without any change. Shaking the bottle produces that nice sound of crystals or granules or whatever (I did not
yet open the bottle). IRC does Ca(OCl)2 produce easier chlorinated hydrocarbons from traces of hydrocarbons in water unlike more safe TCCA and NaDCCA?
|
|
|
theAngryLittleBunny
Hazard to Others
Posts: 130
Registered: 7-3-2017
Location: Austria
Member Is Offline
Mood: No Mood
|
|
Quote: Originally posted by Boffis  | Well; once I had got the orange coloured cake into solution, in 50ml of hot water, nothing crystallised on cooling. The solution was mixed with an
equal volume of saturated KCl solution but still nothing crystallised out, even after 24hours at 5 C. When a small parts was mixed with a little
dilute sulphuric acid a little bromine separated so some bromate was present but not enough to ppt KBrO3. This should not be taken as an indication
that the technique doesn't work since I am pretty sure that I grossly overheated the mixture during evaporation. The viscous calcium chloride filtrate
was also treated with 25ml of saturated potassium chloride solution as mentioned above and about 1.1g of crude K bromate slowly crystallised out.
I am going to try this again using the OP method using a direct ppt of KBrO3 with saturated Potassium chloride solution and also with barium chloride
solution to get the sparingly soluble barium bromate.
[Edited on 16-12-2021 by Boffis] |
How much water did you use to dissolve the Ca(OCl)2? It's important to use as little water as possible. It has a solubility of I think 200g/L at room
temperature, since commercial Ca(OCl)2 is only 70% it should only take maybe 700mL to dissolve 200g of that.
I only did the reaction twice and the 50% yield was my first try, so I can't say how reproducable it is, I might try it again. I think I might also
have used acetic acid instead of HCl or a mix of them in the first run which I forgot to mention, maybe that makes a difference.
[Edited on 19-12-2021 by theAngryLittleBunny]
|
|
|
theAngryLittleBunny
Hazard to Others
Posts: 130
Registered: 7-3-2017
Location: Austria
Member Is Offline
Mood: No Mood
|
|
| Quote: Originally posted by Antiswat | thats the kind of yield you should write into a note on achievements
how doable is it to make calcium hypochlorite yourself? they dont sell it in europe |
If you have to make it yourself make sodium hypochlorite instead, from that you'll start with a clear solution and end up with a clear solution and
you can also make it more concentrated. You might also be able to bubble chlorine into a solution of sodium hydroxide and potassium bromide, forming
the bromate directly in a one pot reaction. The ratios of Cl2 to NaOH to KBr would have to be 3:6:1. That way any NaOCl immediately reacts with the
bromide and you don't really have the problem of hypochlorite decomposing to chlorate.
[Edited on 19-12-2021 by theAngryLittleBunny]
|
|
|
Boffis
International Hazard
Posts: 1836
Registered: 1-5-2011
Member Is Offline
Mood: No Mood
|
|
I have run some more experiments along this theme of hypochlorite oxidation to bromate. I decided to try the direct oxidation of potassium bromide
with 14-15% industrial sodium hypochlorite which is available locally from farm supply stores very cheap. I ran numerous small scale experiments first
and the procedure that gave the best yield was developed as given below.
For my first reasonable scale experiment I dissolved 20.05g of potassium bromide in 280ml of 15% sodium hypochlorite solution with gentle warming and
the neutralised the excess alkali 1:1 diluted 30% hydrochloric acid. It is important to add the acid as close to the bottom of the liquid with a
narrow pipette to avoid loss of chlorine. About 11ml were required to bring the pH down to 6. If the conditions are made more acid loss of chlorine
and bromine occurs, the solution turns deep orange and the yield is reduced.
The solution was then heated to 90-100 C and simmered for 30 minutes. After about 10 minutes crystals started to form on the surface. After the 30
minutes time the hot plate was switched off and the beaker allowed to cool slowly to room temperature (7-8 C) and vacuum filtered, The white platy
crystals were washed with a little water and dried at 45 C for 4 hours to constant weight. The yield was 22.04g which if the crystals are pure
represent 78%.
The filtrate (about 200ml) was treated with 50ml of 1M barium chloride solution causing an immediate ppt. The suspension was heated to boiling at
which point most of the solid dissolved. The suspension was allowed to cool when much crystalline ppt formed. Once at room temperature the mixtures
was vacuum filtered to recover the white barium bromate and the yellowish filtrate discarded. The cake was dried but is rather yellowish and will need
to be re-crystallised.
Both bromates are easily recrystallised from hot water, the K salt requires about 3ml per g (less can be used but it then becomes very difficult to
filter the solution without premature crystallisation, the Ba salt requires about 20-25ml per g.
I am currently working on the bleaching powder process too, a report later.
|
|
|
| Pages:
1
2 |
![[*]](images/xpblue/default_icon.gif){kind=icon}
