PRE-BLEACHING OF MIXED-HARDWOOD PULP WITH SULFURIC ACID

Abstract

The present report describes the experimental method and results of study conducted over mixed hardwood pulp by using sulfuric acid as a pre-bleaching stage. The pre-bleaching of mixed hardwood pulp resulted in more reduction of kappa number of unbleached pulp than oxygen-alkali delignified pulp at same dose of acid. The increase in dose reduces the viscosity.of both pulp below kappa number 8 or above the dose of 35 kg/t. there was minor change in tensile and burst strength of pulp, but the major, drop in tear strength was observed. The pulp was further bleached with DED stage and final pulp properties were observed with optimum dose of sulfuric acid. The final brightness obtained was 80% ISO at kappa factor 0.3 the pulp properties were not much affected.