HCl is often used as reducing agent in production of chlorine dioxide, by there is also formation of chlorine gas which contaminate your end product
with hypochlorite. I think that oxalic acid (or some oxalate) or methanol are better choices, because end product of their oxidation is CO2. Another
cheap alternative is ethanol or sodium bisulfite.
Chlorine dioxide disproportionate in alkaline solution in to chlorite and chlorate - this is why reducing agent must be present in the mixture. Most
often used reducing agent is H2O2, but MeOH also can be used.
Be careful, because gaseous chlorine dioxide is explosive.
[Edited on 11-1-2021 by Bedlasky]woelen - 11-1-2021 at 12:59
It is made commercially by reducing NaClO3 with H2O2 at high pH.
I always thought that you need chlorine dioxide in this reaction (in other words that chlorate can't be reduced by H2O2 in alkaline solution). So why
they bother do it from chlorine dioxide in industrial scale, if they can just mix NaClO3, NaOH and H2O2 together?woelen - 12-1-2021 at 00:05
My mistake, the process is as follows:
- Make ClO2 from NaClO3, HCl and some reductor (frequently, some sulfite or bisulfite is used).
- Pass the ClO2 through a solution of NaOH. This gives NaClO2 and NaClO3. If the alkaline solution also contains H2O2, then only NaClO2 is formed,
together with oxygen. The H2O2 acts as reductor in this case.
My mistake was that I thought that the NaClO3 is reduced by H2O2, but probably, in the presence of H2O2, no chlorate is formed at all, and ClO2 is
reduced and chlorite is formed.Bedlasky - 12-1-2021 at 03:40
Woelen: Maybe you are right. In the link I posted in my original post says:
Even though steps are taken to minimize its production, sodium chlorate must still be reduced before the sodium chlorite can A chemical reaction that
creates sodium chlorite.
A chemical reaction that creates sodium chlorite.
be isolated. This is accomplished by adding extra hydrogen peroxide.
