Improving peroxide bleaching by decreasing manganese induced peroxide decomposition

Pretreatment of pulp fibres with a small amount of hydrogen peroxide under an acidic condition prior to a peroxide stage can improve its bleaching performance. This is explained by the experimental evidence that hydrogen peroxide can reduce high valence manganese, Mn(III), to its low valence form, Mn(II), and that addition of stabilizers, such as sodium silicate and magnesium sulfate, to an Mn(II) system is more effective in decreasing hydrogen peroxide decomposition than if they are added to an Mn(III) system. Detailed results from a laboratory study are presented.