Date of Award
Bachelor of Science
Paper Science and Engineering
Dr. Raja Aravamuthan
This research characterized and optimized the bleaching potential of dimethyldioxirane (DMD) on an -oxygen-delignified hardwood kraft pulp. The DMD wash produced in-situ using a caroate (2KHSO5.KHSO4.K2 SO4) acetone under controlled conditions. The studied variables included chemical concentration, consistency, temperature, reaction time, and chelation. Statistically designed experiments with response surface, methodology were used - to help locate the optimum conditions with respect to pulp brightness and strength. These conditions were located at 2.8% AO (activated-oxygen charge), 5.5% consistency, and 55° C.
It was found that over 95% of the total brightness increase and about 70% of the total viscosity decrease occurs during the first 5 minutes of reaction time. The bleaching response quickly diminishes beyond this initial time. Bleaching. efficiency was improved using a separate chelation stage prior to the DMD stage. Step-wise chemical addition during bleaching improved brightness, but increased viscosity loss.
Thompson, Eric A., "Optimization of a Kraft Pulp Dioxirane Bleaching Stage" (1955). Paper Engineering Senior Theses. 541.