Date of Award

12-1975

Degree Name

Bachelor of Science

Department

Paper Science and Engineering

First Advisor

Dr. Stephen Kukolich

Abstract

The conditions and chemicals for the use of hydrogen peroxide, sodium hydrosulphite and zinc hydrosulphite for the bleaching of groundwood pulp are discussed. Previous research provided guidelines for establishing optimum conditions for temperature, time, pH, consistency and type of buffer. The research carried out determined optimum conditions for a two-stage peroxide-hydrosulphite sequence. The use of an HCl extraction prior to bleaching was found to be as effective as EDTA for the removal of heavy metals. The combination of peroxide-hydrosulphite gave a brightness rise of 26 G. E. points while hydrogen peroxide alone gave 22.2 points and hydrosulphite alone gave 8.7 to 11 points. The effects of combination bleaching are not totally additive.

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