Oxidation of sulphur species on active carbons: the suggested mechanism

The oxidation of sulphur (II) species with oxygen in the absence of catalysts is very slow, due to the unfavourable symmetry of the spin state resulting from the different
electronic configurations of the reactants. Among the efficient catalysts for the oxidation of sulphur (II) species the activated carbons are indicated, being able to
change the electronic configuration of the reactants (S(II) or O2). The type of the products and intermediates formed during the oxidation process with oxygen depends largely on pH, reagents concentrations (S(II), oxygen), and the type
of the activated carbon (as catalyst).
In this work the experimental results were corroborated with literature data, and plausible mechanism or reaction scheme was suggested for each case of active carbon used.