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Mass transport of chemicals into wood is important in kraft pulping. This thesis models small wood particles as cylinders and monitors how tritiated water and sulfide diffuse into the water-filled pores. Tritiated water diffusion is Fickian and diffuses completely into the water contained in the wood. Tortuosity values of the aspen and pine are tabulated. As particle size decreases, the tortuosity of the particles increases. As sulfide diffuses into wood, it is occluded from some water filled areas. Charge exclusion is a possible explanation for this. Sulfide and hydroxide transport into wood chips was displayed using indicators for each component. Pictures show sulfide ingress into the chip core faster, thus confirming the diffusion results. Fractionated sawdust was pulped to determine particle size effect on cooking and pulp properties.

Thesis (Ph. D.)--Institute of Paper Chemistry, 1979. / Includes bibliographical references (leaves 81-82).

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A mechanism for the mass transfer of anthraquinone (AQ) into wood during alkaline pulping has been developed. Although the chemistry of action of AQ is well-developed, there has not been much work conducted on its diffusion properties. The discrepancies between different experiments with AQ indicate that something other than the chemistry is at work. Because most of the differences arise from differences in pulping conditions, it is likely that mass transfer is the source of these discrepancies. A model system was therefore developed to explore the mass transfer properties of AQ. It was shown that AQ must be reduced to anthrahydroquinone (AHQ) at the membrane surface before any permeation of a membrane can occur. It was also shown that increasing surface coverage of the membrane through AQ particle size reduction could improve the rate of membrane permeation. The mechanism described by the model system was then tested against pulping data. It was shown that the addition of surfactants increases the pulping efficiency of AQ. This is probably through better dispersion of AQ particles to cover more chip surface area. Bulk reduction effects were also tested, and it was shown that bulk phase reducing agents decrease the efficacy of AQ in pulping. This led to the development of the mechanism for AQ diffusion in alkaline pulping.

Thesis (M.S.)--Brigham Young University. Dept. of Mechanical Engineering, 2006. / Includes bibliographical references (p. 137-140).

Thesis (Ph. D.)--University of Washington, 2007. / Vita. Includes bibliographical references (leaves 86-89).

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