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clearly_not_atara
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A new challenger approaches:
https://pubs.rsc.org/en/content/articlehtml/2024/cc/d4cc0250...
| Quote: | | While the tremendous potential of peroxodicarbonate as a sustainable oxidant was recognized early on, reports on applications up until 2022 have been
sparse, since the challenging synthesis and the low overall concentrations of peroxodicarbonate posed large obstacles.33 This changed with the
publication of the landmark paper by Waldvogel and Gooßen.45 One important aspect which was solved is the enhancement of the carbonate concentration
in aqueous media. When using a mixture of sodium and potassium carbonate, a peroxodicarbonate concentration of up to 0.337 M was obtained in a similar
setup to that of Comninellis and co-workers.33 By adding bicarbonate to the solution the concentration of peroxodicarbonate could be further enhanced
to 0.406 M. The authors assumed that bicarbonate balances the hydroxide ions released over the course of the electrolysis. Consequently, a composition
of 1.125 M K2CO3, 0.9 M Na2CO3 and 0.225 M KHCO3 provided optimal results.To achieve even higher concentrations, not only was the composition of the
electrolyte crucial, but also the heat dissipation during and after the electrolysis event. It was found that efficient cooling by addition of an
in-line heat exchanger resulted in a concentration of 0.588 M.45 Based on this finding, a new electrolysis cell design with an elaborate heat-transfer
system was developed, enabling the production of peroxodicarbonate with a concentration of up to 0.919 M. |
...
| Quote: | | The total content of oxidizing agents can be determined by adding H2SO4 and converting all peroxodicarbonate species into hydrogen peroxide.
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[Edited on 8-9-2025 by clearly_not_atara]
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Mister Double U
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An interesting read!
With a well-designed cooling system, it could be a route.
I have also thought about a switch of the chemical compound for H2O2 generation. My choice would be Sodium Perborate. I have tried the electrolysis a
couple of times, but without any success. The white powder which crystalized from the solution was simply Sodium Tetraborate (Borax). This is probably
due to the acid environment around the anode. I remember mixing NaHCO3 stoichiometrically with Borax to make Sodium Metaborate by boiling down the
solution. This seems to be not the right ratio. 'The Manufacture of Chemicals by Electrolysis' states "45 grams of borax and 120 grams of sodium
carbonate per liter".
This method would also come with the benefit, that one Perborate molecule contains 2 peroxo groups.
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Alkoholvergiftung
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Perborate should be similar to Potassiumpercarbonate. They are made with an diaphragma cell with an Pt Anode and an Pt Kathode. The Chamber is cooled
down to -16C. The temperatur is allowed to fluctuat betwenn -10 C and -15 C.
high current densitys are favored. Source " fabrikation of Bleaching Agents"
Maybe you need to work with lower temerpatures.
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clearly_not_atara
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According to the paper, BDD works better than Pt for percarbonate.
Primarily I think percarbonate is of interest because it is more easily hydrolyzed, so the peroxide can be obtained from a solution containing less
H2SO4. Also, probably bisulfate can be substituted as the acid for hydrolysis (it is reported to be hydrolytically unstable below pH 8!), avoiding
H2SO4 altogether. But even a concentration of 0.9M is relatively low. So in order to obtain a good concentration of H2O2 from e.g. K2C2O6 you would
most likely want to precipitate the salt and then hydrolyze it with acid. Alternatively, you may concentrate the solution under vacuum. But I think
you will find that crystals form.
| Quote: | Potassium peroxodicarbonate, obtained
as a microcrystalline, light blue powder, was filtered and washed with
ethanol and diethyl ether. The peroxide content was determined iodo-
metrically. [16] K 2 C 2 O6 decomposes rather slowly when stored below 20 8C
for several weeks (8 % per week)
According to the results of thermal analysis (DTA/TG/MS; Metzsch STA
429; 20 8C ± 800 8C; 2 8C min1 ) and in agreement with previous exper-
iments, [3e] K 2 C2 O 6 decomposes at 141 8C by generation of oxygen and
carbon dioxide.
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https://onlinelibrary.wiley.com/doi/abs/10.1002/1521-3773(20020603)41:11%3C1922::AID-ANIE1922%3E3.0.CO;2-T
Thankfully, it does not appear to be a violent decomposition 
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