Oxidation of bleached wood pulp by TEMPO/NaClO/NaClO2 system: Effect of the oxidation conditions on carboxylate content and degree of polymerization

Abstract

Oxidation of bleached wood pulp by the TEMPO/NaClO/NaClO2 system was carried out at pH 3.5-6.8 and 25°-60°C with different amounts of NaClO, and investigated in terms of effects of the reaction conditions on carboxylate content and degree of polymerization (DP) of the oxidized pulp. Oxidation was accelerated by the addition of NaClO, when carried out at pH 6.8 and 40°-60°C. Addition of NaClO of more than 0.5 mmol per gram of the pulp was effective to accelerate the oxidation. Carboxylate content of pulp oxidized under such conditions increased to approximately 0.6 mmol/g within 6 h. Although DP of the oxidized pulp gradually decreased with oxidation time, no significant differences in DP of oxidized pulps were found at oxidation temperatures between 25° and 60°C, and DP values of more than 900 were maintained after oxidation for 54 h at 60°C. © 2010 The Japan Wood Research Society.