Formation
Patented in 1986, the primary method of isolating Sodium Selenate is to dissolve metallic selenium in nitric acid, producing selenous acid. The selenous acid is then treated with an alkali metal hydroxide, alkali metal carbonate and/or some other metal oxide/hydroxide to form an alkali metal selenite. Next, the selenite is oxidized in a basic environment with an oxidant in the form of hydrogen peroxide to form a selenate, which is then spray-dried.
- Reaction
- Se + 2HNO3 → H2SeO3 + NO + NO2
- H2SeO3 + Na2CO3 → Na2SeO3 + H2O + CO2
- Na2SeO3 + H2O2 -> Na2SeO4 + H2O.
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