Activator for the Peroxide Bleaching of Mechanical Pulp, 1996 Pulping Conference Proceedings

C. Leduc, C. Montillet and C. Daneault

Université du Québec à Trois-Rivières,

In-situ activation of peroxide via the use of TAED to produce strong oxidant is a safe and low cost (capital intensive) alternative to the use of pre-formed peracids or other strong oxidizing agents. Unlike pre-formed peracids, the combination of TAED and peroxide can provide effective bleaching. TAED is a colourless, stable solid which is safe and easy to handle. It is biodegradable and non-toxic. In alkaline medium, one mole of TAED reacts with two moles of perhydroxyl ion (hydrogen peroxide) to produce two moles of peracetic anion. Generally peracids are considered to be better and more active bleaching agents than peroxide. In this study, we have investigated various aspects of peroxide process of a commercial thermomechanical softwood pulp. Important factors such as temperature, time, charge, peroxide/TAED ratio, alkalinity, and buffer have been studied in order to maximize the brightness gain. Considering the fact that the bleaching process varies from mill to mill, experiments have been conducted to evaluate the impact of the sequence of addition of activator in one- and two-stages using peroxide and TAED. The use of TAED in the peroxide bleaching liquor offers a mean to improve the pulp brightness significantly. An enhanced bleaching efficiency is achieved using a short time cycle. It implies less required energy and a reduction in production cost. KEYWORDS Mechanical pulp, Bleaching, Oxidizing agent, Hydrogen peroxide, Activator, Tetraacetyl ethylenediamine, TAED