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Thesis (M.S.)--Oregon State University, 1970. / Typescript. Includes bibliographical references (leaves 57-59). Also available on the World Wide Web.

Thesis (Ph. D.)--University of Tennessee, 2007. / Title from title page screen (viewed on November 1, 2007). Thesis advisor: David A. Buehler. Vita. Includes bibliographical references.

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Gasification of black liquor could drastically increase the flexibility and improve the profit potential of a mature industry. The continuous efforts made in the area of black liquor gasification (BLG) are bringing this technology closer to commercial realization and potential wide-spread implementation. Research exploring the integration of BLG into the kraft process and the potential of BLG enabled modified pulping technologies on modern pulping operations is important to support this effort. The following effort is focused on such research, utilizing laboratory pulping experiments and process simulation. The separation of sodium and sulfur achieved through gasification of recovered black liquor can be utilized in processes like modified continuous cooking, split sulfidity and green liquor pretreatment pulping, and polysulfide-anthraquinone pulping to improve pulp yield and properties. Laboratory pulping protocols have been developed for these modified pulping technologies and different process options evaluated. The process simulation work around BLG has led to the development of a WinGEMS module for the low temperature MTCI steam reforming process, and case studies comparing a simulated conventional kraft process to different process options built around the implementation of a BLG unit operation into the kraft recovery cycle. The implementation of gasification, functioning as the core of wood pulping recovery operations in a biorefinery, would enable the application of modified pulping technologies while creating a synthetic product gas that could be utilized in the production of value added products in addition to wood pulp. The evaluated modified pulping technologies have indicated the potential of yield increases of 1-3% points with improved product quality, and the potential for capital and operating cost savings relative to the conventional kraft process. Process simulation work has shown that the net variable operating cost for a pulping process using BLGCC is highly dependent on the cost of lime kiln fuel and the selling price of green power to the grid. Under the initial assumptions taken in the performed case study, the BLGCC process combined with split sulfidity or PSAQ pulping operations had net variable operating cost 2-4% greater than the kraft reference. When comparing the BLG cases to the MCC reference, the net variable operating cost break even point based on lime kiln fuel cost is about $47/barrel for the split sulfidity and lower charge polysulfide processes, and about $38/barrel for the higher polysulfide charge process. This is significantly lower than assumed kiln fuel price of $60/barrel used in this work. If the sales price for power to the grid could be increased through green power credits from 3.5 to 6 ¢/KWh cost savings of about $40/ODtP could be realized in the investigated BLG processes. Other alternatives to improve the process economics around BLG would be to modify or eliminate the lime kiln unit operations, utilizing high sulfidity green liquor pretreatment, PSAQ with auto-causticization, or converting the process to mini-sulfide sulfite-AQ.

The objective of this research is to understand the interfacial behavior of cellulase enzymes and its effect on cellulose hydrolysis. This research began with an in-situ monitoring of cellulose hydrolysis using a piezoelectric based quartz crystal microbalance. The time-course kinetics was modeled using a dose response model. The adsorption indicated by the frequency drop followed a Langmuir model as cellulase enzyme increased. Another important part of this research is the development of a new cellulase activity assay based on the piezoelectric technique. This assay provides an easier and more user friendly method for cellulase enzyme activity measurement. It also helps to clarify an element of the interpretation of frequency drops after the injection of cellulase solutions in the hydrolysis of cellulose film, which has been neglected in previous research. Interfacial adsorption of cellulase protein was also investigated using the depletion method. The effects of substrate properties, primarily the crystallinity, which was characterized using X-ray diffraction, were investigated. The effect of surface area, which was measured using both laser light scattering and BET adsorption, on cellulase adsorption were also investigated. It was found that crystallinity played a more important role in cellulase adsorption than surface areas of cellulosic substrate. In characterization of cellulosic substrates, the water retention value (WRV) was also investigated. The results indicated that lower crystallintiy substrates have higher water retention ability. The cellulase adsorption, as well as desorption, was also studied by using sodium dodecyle sulphate polyacrylamide gel electrophoresis (SDS-PAGE). The adsorption results followed the same trend as indicated by the depletion methods. The various isozymes demonstrated a uniform adsorption in proportion to their concentrations. Desorption appeared uniform. Higher pH was found to create higher desorption for a particular cellulase from a particular substrates. It was also found that cellulase from Trichoderma reesei had higher affinity to cellulosic substrates used in this work than the one from Aspergillus niger.

The objective of this research is to understand the drying behavior of cellulose fibers characterized by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). A parameter termed ?hard-to-remove (HR) water content? was defined as the ratio of water mass to fiber mass at the transition between the constant and falling rate drying zones of an isothermal TGA experiment. The HR water content showed a linear relationship with water retention value. TGA and DSC were used to explain the linear relationship. During drying, free water was observed to evaporate first, followed by trapped water, freezing bound water and then non-freezing bound water, with some overlap. Trapped water can be described as water bound to the fibers, but difficult to evaporate. For pilot papermachine samples, all the water in the wet web entering the dryer section was HR water, with no free water detected. Based on the results, a qualitative drying model of cellulose fibers was proposed with regard to decreasing moisture ratio. Changes in the pore size distribution during drying were determined using DSC measurements and the Gibbs-Thomson equation. Larger pores collapsed first followed by the sequential collapse of smaller pores, indicating that pore wall collapse resistance is critical. The average pore size for bleached softwood was calculated to be about 80 nm and decreased with drying. A constant pore size of about 20 nm was observed at moisture ratios below 0.3 g/g, which corresponds to one-to-two layers of non-freezing bound water. The heat of vaporization of water associated with cellulose fibers was determined using modulated DSC and showed a steep increase at moisture ratios below 0.3 g/g, indicating that a higher energy is required to evaporate non-freezing bound water.