The current paper recycling processes are surveyed pointing out the major stages and the variety of chemical/mechanical treatments the fibres undergo. The reduction or replacement of chemical/mechanical treatments presents possible advantages in prolonging fibre life. The results from recycled office waste which has been treated with ultrasound show a change in the particle size distribution of toner particles - making these particles easier to remove using established flotation techniques. Particle size distributions were measured using image analysis on thin (20gsm) paper handsheets. To establish the affect of sonication on fibres, a variety of virgin fibres were obtained from UK Paper, Sittingbourne. Results from virgin fibres which have been treated using ultrasound indicate an absence of cutting compared to conventional techniques. Fibres were found to have the same average length (0.6mm) after ultrasound treatment as the control sample, refined fibres were reduced to approximately 0.3 mm in length. Freeness decreased in both virgin sonicated and refined sonicated samples. The decrease in freeness was accompanied by an increase in the strength properties of both categories of fibres. Experiments with a prepared office waste furnish showed that ultrasonic treatment could decrease the size distribution of fused toner particles. The control sample had an average size of 80.9 um, after 1 minute sonication this was decreased to 54.9) um, decreasing further to 46.8)um after 2 minutes sonication. After demonstrating that ultrasound could decrease the particle distribution of the prepared office waste a more realistic and variable furnish was used. The experiments were conducted at room temperature, 50°C and 75°C. These temperatures were chosen to study the behaviour of fused toners as it approaches and exceeds its glass transition point, essentially the melting point of an amorphous polymer. It was found that the toner is easier to remove as the glass transition temperature is approached. Ultrasound is effective in breaking up large toner particles and detaching particles smaller than 25 microns in diameter.

Thesis (M.B.A.)--Boston University

This thesis combines documentation of book, installation, and social art projects from 2012-2015 with reflections on intentions, influences, concepts, and questions.

Anatomia Botanica explores the relationship I have come to develop with my natural environment. It takes the reader through my understanding of three species of flowering plants. These are plants that had a significant impact on my childhood and early adulthood, teaching me to look at our natural environment as far more complex and compelling of respect than we give credit to.

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.

Lignin, the glue that keeps fibers together, is a complex three dimensional network polymer which has shown association phenomena in solution. Following the molecular weight of the biopolymer in solution as a function of time allow us to explore their observable de-association phenomena. These measurements were carried out using multiple angle light scattering (MALS) photometry in the static mode. EMAL (Enzymatic Mild Acidolysis Lignin) from hardwood and softwood were isolated and an additional method for the complete dissolution of such biopolymers in THF was further developed. Once the challenge of the measurement procedures were worked out, some rather accurate dn/dC values for lignin solutions were obtained as a function of time. This effort when coupled to additional work using static light scattering measurements (Zimm plots) for the same solutions offered an insight into the self-assembly processes operating within the lignin biopolymer.

Polyampholytes are polymers that have both positively and negatively charged groups in the same chain. In recent years polyampholytes have started to be used in papermaking applications, as well as in sludge treatment processes. Benefits, in the case of papermaking, have included increased dry-strength and faster removal of water. But the molecular mechanisms by which such benefits are achieved have not been fully understood. This thesis project focused on effects related to polyampholyte charge density. A series of polyampholytes with a fixed charge ratio but different charge density was used for the experiments. Analysis methods included pH titrations, streaming current titrations, and adsorption isotherms. From pH titrations the charge density of cationic and anionic groups under different pH were calculated. From streaming current tests the net apparent charge density under different pH was calculated. And from adsorption tests it was found that the highest adsorbed amounts were achieved in certain cases corresponding to the highest content of ionic groups on the polyampholytes. Adsorption depended strongly on pH. Substantial differences were observed when comparing results obtained with polyampholyte samples versus ordinary polyelectrolyte samples with same charge density of cationic or anionic groups.

This study aims at elucidating a variety of salient features that dictate the kinetics and chain length effects governing the formation and antimicrobial activity of sugar esters of fatty acids. To do this, anomerically pure glucose, sucrose and cellobiose sugars were transesterified with the methyl esters of fatty acids of variable chain lengths C4, C8, C12, C18, and C20. The methyl esters of butyric, caprylic, lauric, stearic and arachidic acids were reacted with the above carbohydrates to give the respective penta and octaesters. The kinetics of these transesterification reactions were followed by quantitative 31P NMR after phosphitylation of the labile OH groups with 1,3,2- dioxaphospholanyl chloride. This approach proved to be a facile and quantitative means to follow the specific substitutions occurring at the various OH positions within the sugars as a function of degree of conversion, and incoming chain length. As anticipated, a variety of steric and hydrophobic effects were shown to play a key role in determining the reactivity of these systems. The various sugar esters were then adsorbed onto cellulose disks and their microbial activity was examined. Finally, cellulose esters of butyric acid were synthesized using the acyl chloride process.