[Bill]

Hello,

I am master student from belgium and I'm trying to investigate the parameters that have an influence on the production of H2SeO3. H2SeO3 is produced by oxidising Se-residue with H2O2. The problem is the formation of selenic acid (H2SeO4). The thing is when you look at the pourbaix diagram, H2SeO3 as well as H2SeO4 is formed at a certain pH and potential. My goal is to reduce the formation of Se(VI) in the form of H2SeO4.

So far I am doing a litterature study on the mechanics of the formation of H2SeO4 and H2SeO3 but I can't find a lot of articles on this subject. Can anyone give me advice how or where to look to serve this problem.

Thank you

[AWK]

The method with hydrogen peroxide produces mainly H₂SeO₄ (JACS 58(1), 180, 1936.

http://en.wikipedia.org/wiki/Selenic_acid
http://en.wikipedia.org/wiki/Selenium

[Hunter2]

Better is to oxidize selenium with nitric acid

http://en.wikipedia.org/wiki/Selenium_dioxide

[AWK]

... and even directly to H₂SeO₃ with diluted HNO₃.

[Bill]

The reaction that occurs in the reactor is:
Se (residu) + 2H₂O₂ SeO₂ + 2H₂O H₂SeO₃ + H₂O

The thing is that I can't change the way they oxidize the Se-residu. So I need to figure out what parameters can influence the formation of selenic acid. The parameters I think that can influence this reaction, is the concentration of other metals in the Se residu, the rate by which they add H₂O₂. I added a file with a simplified diagram of the process.