symboom
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Synthesis of Sodium Perborate
According to
http://www.prepchem.com/synthesis-of-sodium-perborate/
Also the procedure is there
3 percent hydrogen peroxide is used surprisingly
This does decompose in water
Though im not sure what causes its breakdown
Heat and neutral pH water
Materials
Sodium Hydroxide
3 percent hydrogen peroxide
Borax
Has anyone done this synthysis
Nothing on youtube seems straight forward
[Edited on 13-12-2016 by symboom]
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j_sum1
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It seems pretty straightforward. I wonder how much stays dissolved when recrystallising and whether yield might beincreased with more concentrated
peroxide.
Give it a shot and tell us how you got on.
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PeterC
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Sodium perborate hydrolyses with water so you might want to cool everything down to see if you can get any crystals and/or use less water.
Chemplayer's video perborate: https://www.youtube.com/watch?v=0pKr5VSYhwY
EDIT: Your issues are probably caused by the weak peroxide (3-6% is way to weak for something like this).
[Edited on 13-12-2016 by PeterC]
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exodia
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If I'm right the video from chemplayer is on sodium percarbonate, I did see a couple of replies to the video sending info and links on sodium
perborate.
which is the same one that the one symboom posted
[Edited on 20-12-2016 by exodia]
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chemplayer...
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You need to watch our Christmas special for sodium perborate. The other video was indeed on sodium percarbonate.
https://www.youtube.com/watch?v=Nz8RUio4_UE
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Fyndium
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I prepared sodium perborate from sodium percarbonate detergent with success. I dissolved borax in hot water, added NaOH, cooled the solution and added
it to a solution of sodium percarbonate based stain removal detergent. Very little heat was evoluted, only 1-2 degrees, because the reaction mass is
so huge compared to the more ordinary version which uses hydrogen peroxide, so basically the borax solution can just be dumped in.
The perborate takes time to settle, and it should be left for at least an hour for full settling. I hesitated once again, and when I was dumping the
waste solution, I discovered a batch-worth more from the bottom and saved it from the drain.
The perborate was decanted to minimun volume, ethanol was added to coagulate it even more, filtered with vacuum to remove liquid, washed twice with
ethanol, dried over suction and placed in desiccator bag. Result was white fluffy crystals that appear similar to the ones in pics in SciMad wiki and
youtube videos. When I get to use it in Baeyer-Villiger, I will see if it's what it's supposed to be.
I don't know how it could be recrystallized. It decomposes in hot water and sol data for other solvents is unknown.
The yield was pretty much quantitive based on molar ratios and presumption that the detergent gunk contains about 60% of percarbonate, balance being
ordinary soda, stink agents and other annoyances. The detergent peroxide content is most likely a little excess, which is good because the solubles
will be filtered off and it should result in more total conversion. Final measurement for weight is yet to be done, because the mass is not yet fully
dry, but I expect 5 to 10 % loss at max based on the free-flowing appearance.
The volume of the solution is rather large, for 50 grams of produce the total volume will be over 1 liter, because sodium percarbonate has only 150g/L
solubility, so producing larger quantities will quickly result in need of very large reaction vessels.
[Edited on 14-10-2020 by Fyndium]
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Fyndium
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Developments for the process:
The solution containing the percarbonate detergent must not be agitated with strong stirring when adding the sodium metaborate, because perborate
crystals forming will be very fine and tend to form suspension and take more time to settle.
Some perborate seem to coagulate on the surface, and very little stirring will cause them to settle.
Upon decanting, the liquor should be left to stand because generally second batch will precipitate. Even third, small final batch can be obtained
after longer waiting. Waiting for very long seems to be less optimal because the liquor remains in suspension state, and decanting the liquid seems to
agitate the settling process, hence taking two or three steps seems to be quite optimal.
The precipitates can be put into large paper filter on top of sieve and left to drain all the liquid off, which contains water, sodium carbonate and
detergent residues. When a mush is left, it is washed with water, which will wash away sodium carbonate and detergents, and then the mass is washed
with ethanol to reduce water and detergent compounds. Finally it is suctioned dry and desiccated to obtain white, free-flowing powder.
The process suffers from high losses due to large volume of liquid. About 30% of perborate will be lost due to solubility. The solubility is 20g/L,
and apparently the perborate/carbonate decomposes in water if it is heated(the source states that perborate quickly decomposes at 60C), so the
reaction must remain below 25-30C preferably. It is left for the consideration of personal matter if it is more feasible or cost-beneficial to perform
the process either with otc sodium percarbonate, or hydrogen peroxide. Somewhat large input of detergent powder is needed, because, as usual, the
manufacturers seldom use pure and good stuff, but instead cut the products with all kind of fillers. For 1 mol scale reaction(from borax), it seems
that over 1200g of powder is needed, when the 40% of filler is deducted and the remaining contains 1.5 moles of H2O2 per mole of sodium carbonate. Due
to calculating variables based on different sources of the reaction mechanism, a 600-gram initial batch resulted in significantly lower yield of
perborate, indicating that the former number seems to be the correct ratio. Considering the maximum theoretical yield is about 600 grams, 365 grams
were obtained from the batch, which represents a loss of 200g left into the main solution, and the rest are apparently processing losses due to
decomposition, decanting, washing steps and material left in containers.
[Edited on 16-10-2020 by Fyndium]
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