Author

Simelane

Date of Award

4-1996

Degree Name

Master of Science

Department

Chemical and Paper Engineering

Department

Paper Engineering, Chemical Engineering and Imaging

First Advisor

Dr. Raja Aravamuthan

Second Advisor

Dr. David Peterson

Third Advisor

Dr. E. Shriver

Access Setting

Masters Thesis-Open Access

Abstract

The main objective of this study was to investigate the effect of adding a pretreatment stage in conventional hydrogen peroxide bleaching of high yield pulps. To achieve this, three main variables considered crucial in the effectiveness of manganese peroxidase on the oxidation of lignin substructures, were chosen to evaluate the effect of this enzyme on high yield pulps. The responses to evaluate this effect were brightness, brightness reversion, pulp viscosity, and yield. Other properties included opacity, scattering and absorption coefficients, and the Hunter Lab values.

The pulps were bleached using two sequences Q(MnP), and Q(MnP)QP, to assess the effect of the enzyme alone and when it was a pretreatment. Malonate buffer concentration, MnP charge, and pH were the three factors used and they were varied between two levels, high and low.

An analysis of the data indicate that both sequences raised the brightnesses of the two pulps. Following Q(MnP)QP bleaching, brightness reversion was reduced, pulp viscosity was maintained and sometimes raised, and the yield dropped by about 10%. The bleaching method used in this study was found to be not as effective in bleaching oxygen delignified softwood kraft pulp.

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