Co(II) catalyzed oxidation of organic compounds by peroxomonosulphate

The Co(II) ion catalyzed decomposition of peroxomonosulphate (PMS) and the influence of organic substrates such as ethanol, t-butanol, a-hydroxy acids (AHA) and glycine is studied at pH <= 1.0 and 4.0-5.2. In strong acid medium, the reaction is inhibited by the organic compounds and the present results, in accordance with the earlier reports, suggest redox process through the formation of sulphate radical intermediate. Ethanol and AHAs are more effective quenchers than t-butanol. However in buffered medium (pH 4.05-5.20), the substrate other than t-butanol catalyze the reaction and get oxidized quantitatively. Ethanol is oxidized in the presence of AHA and glycine, suggesting a molecular mechanism involving a complex intermediate EtOH-Co(II)-SO52- and subsequent oxygen atom transfer from SO52-. The catalytic effect, of Co(II) is observed with concentrations of ppm or lower level.