A catalyzed chemimechanical-anthraquinone pulping of black spruce wood was investigated in this study. The effect of liquor pH on anthraquinone performance, AQ and mass transfer limitations on chemimechanical pulp properties and the effects of AQ, liquor pH and sulphite concentration on pulping kinetic were studied. / It was observed that AQ was not an effective redox catalyst when added to the sulphite liquor at pH 4, but it was very effective at pH 7 and higher. When chemical treatment of chemimechanical pulping was done with the presence of AQ, the sulphur content of pulp was reduced due to preferential reaction of AQ with wood components. AQ, as a pulping agent, is much effective in increasing the delignification rate and at the same time protecting the degradation of carbohydrates. / Pulps produced from wood wafers with cooking liquor at pH 7 containing 0.1% of AQ on oven dry wood, exhibited the following improved properties when compared with those prepared without addition of AQ: increased pulping rate, higher pulp yield and carbohydrates yield at the same level of residual lignin in pulp, and in addition, the strength properties such as breaking length and burst strength improved by 15% even with a minimum AQ charge (0.05% and 0.01%). / With regular wood chips, the penetration of sulphite seems to be superior to that of AQ. It was observed that AQ was not uniformly distributed in the impregnated wood chips even when the compression ratio was increased from 3.5:1 to 5:1. The penetration of AQ into wood chips remains to be a major factor affecting the pulping rate and pulp properties (strength and brightness) in chemimechanical-AQ pulping. / The rate of delignification in the initial phase of both sulphite and sulphite-AQ cooking at pH 7 shows the second order reaction in the remaining lignin. The order with respect to sulphite concentration for sulphite and sulphite-AQ cooking were estimated to be 0.24 and 0.31, respectively. The activation energies of delignification of the initial phase in sulphite and sulphite-AQ pulping were 90.2 and 97.5 kJ/mole which was valid up to 30% lignin removal within the temperature range of 160°C and 175°C. AQ as a pulping additive introduced to the sulphite liquor increased the rate of delignification 1.5 times in the initial phase of delignification during the sulphite cooking process. / At initial pH of sulphite liquor ranging from 7 to 10, the rate of delignification in the initial phase during sulphite and sulphite-AQ cooking appears to be a second order reaction in the remaining lignin. The reaction orders with respect to sulphite concentration increases when the initial pH is below 8 and decreases when the initial pH is above 8 for both sulphite and sulphite-AQ cooking. The raw of delignificafion is dependent on the initial pH of cooking liquor and the addition of AQ.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.35431 |
| Date | January 1997 |
| Creators | Wang, Biao, 1963- |
| Contributors | Kubes, G. J. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Chemical Engineering.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001656554, proquestno: NQ50278, Theses scanned by UMI/ProQuest. |
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