Date of Award

12-1990

Degree Name

Bachelor of Science

Department

Paper Science and Engineering

First Advisor

Dr. Ellsworth Shriver

Abstract

Hydrogen peroxide is an oxidizing bleaching agent that is utilized extensively in the pulp and paper industries to bleach cellulosic fibers to high brightness levels. The main advantage of hydrogen peroxide bleaching of mechanical pulps is the high yield. Peroxide used under mild alkaline conditions can significantly increase brightness 10-20 points by oxidizing lignin constituents without actual lignin degradation. Due to peroxides' inherent quality of lignin preservation, it is an excellent bleach for application to CTMP. This allows a high yield process like BCTMP to compete with kraft pulp in application to many grades of paper.

Peroxide is an expensive bleach agent and it is of utmost importance to achieve sufficient control and understanding of its effects in order to receive maximum benefits while minimizing consumption. The purpose of this thesis will be to optimize the brightness response of the CTMP bleaching process with hydrogen peroxide by periodic additions of bleach liquor at various charges while maintaining a specific process pH.

After bleaching trials were completed, brightness increases of 12 points were achieved with 3% peroxide bleach liquor addition. It was confirmed that increasing applications of peroxide increases the achievable brightness. The application of peroxide at different times during the experiment with pH control show no significant difference to a procedure of full beginning liquor charge with no pH control. It is also concluded that heavy metal ion chelation is a requirement and sufficient mixing is recommended to achieve all the benefits of hydrogen peroxide utilization.

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