AUTOOXIDATION OF SULFITE IN ALKALI MEDIA

The rate of sulfite ion antooxidation by oxygen in the alkali media wa s studied at different pH. It was shown that, at pH > 10, the reaction rate drastically decreased, whereas at pH 12, it virtually became equ al to zero. This is due to the transformation of iron ions, which play the role of an initiator and are present in trace amounts, into inact ive insoluble iron(II) hydroxide. In the case of sulfite oxidation by free radicals generated by pH-independent homolysis of peroxydisulfate , the reaction rate at pH > 10 remains constant in agreement with the chain mechanism of the process.