[AlMn(II)(H(2)O)W(11)O(39)](7-) Anion oxidation kinetics and simulative overall studies of catalytic oxygen bleaching

The kinetics of a reaction between the polyoxometalate (POM) anion [AlMn(II)(H(2)O)W(11)O(39)](7-) and O(2) at various conditions (pH 3, 5, and 7; reaction temperature 55, 66, and 76 degrees C; oxygen pressure 0.3 and 0.5 MPa; ionic strength 0.05 mol V) was determined. Oxidation was observed only at pH 3 and 5, at temperatures 66 and 76 degrees C and at oxygen pressure 0.5 MPa. According to the reaction scheme postulated, superoxide and hydroperoxy radicals inhibit the oxidation of the POM anion. Unknown kinetic parameters of the scheme were optimised; the activation energy of the oxidation reaction was determined to be 112 +/- 16 kJ mol(-1). Bleaching simulations based on the optimised parameters suggested that the investigated POM is likely to be inefficient in catalysing oxygen delignification of chemical pulp.