Physical Sciences and Mathematics Commons^™

Mechanistic Studies Of The Oxidation Of Lignin And Cellulose Models, Oh-Kyu Lee

Electronic Theses and Dissertations

Oxygen delignification is an environmentally friendly pulp bleaching system. To develop a selective delignification process that results in high DP retention of carbohydrate with lignin being removed, obtaining better knowledge of reactions occurring during oxygen delignification is essential.

In this work, mixtures of guaiacol (model lignin) and methyl-ß-D-glucoside (model cellulose) were reacted in a pressurized oxygen reaction system (pH 12,65 psi O₂, and 95°C in a glass reaction vessel). In the results, methyl-ß-D-glucoside degraded only in the presence of lignin. This indicates that hydroxyl radicals, that subsequently react with methyl-ß-D-glucoside, are generated in the system. Unfortunately, we could …

Oxygen Delignification Kinetics And Selectivity Improvement, Steven M. Violette

Electronic Theses and Dissertations

Pulp strength loss during oxygen delignification is caused by cellulose chain cleavage resulting fiom attack by oxygen-based radicals generated through reactions with lignin. The objective of this research was to improve the lignin-to-cellulose selectivity during oxygen delignification by using radical-scavenging polymeric additives that adsorb on the cellulose surfaces where protection fiom radicals is needed. Among the polymers evaluated were starch, carboxymethyl-cellulose, galactomannan, xylan, and glucomannan. Oxygen delignification experiments were conducted on Northeast softwood Kraft pulps at different temperatures, sodium hydroxide charges, reaction times, and pretreatments. The effect of polymer additives on the selectivity and kinetics was studied. Polymer adsorption on …

Effect Of Kraft Pulping On Oxygen Delignification, Haixuan Zou

Electronic Theses and Dissertations

The objective of the study reported here was to investigate experimentally the effect of the major Kraft pulping variables on the response of brownstock pulps to medium consistency oxygen delignification. Kraft pulping was performed on mixed Northeastern hardwood chips in a laboratory rocking digester. Kraft pulps of kappa number 16 and 20 mL KMnO₄ were produced by pulping under a variety of conditions. The effective alkali (EA) charged to the digester was varied over the range of 12 to 21% while the sodium sulfide content of the pulping liquor was varied between 0 to 30% sulfidity. Cooking temperatures of …