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Bioreactor landfills have become a feasible alternative to the typical "dry tomb" landfill. By recirculating leachate and/or adding additional liquid wastes, bioreactor landfills operate to rapidly degrade and transform organic wastes. The reactions within a bioreactor landfill create elevated temperatures. The intent of this study was to determine the effect of elevated temperature on the degradation of lignocellulose compounds. In order to observe the effects of temperature on lignin, small bioreactors were created in the laboratory. Several experiments were performed by the authors. Solubility of lignin based on temperature and time of thermal exposure were conducted. In addition, degradation studies were conducted based on biological treatment of lignin as well as a combination of biological and thermal treatment. Samples were collected at specified intervals to determine the amount of water soluble lignin (WSL), volatile fatty acids (VFAs), lignin monomers, and/or methane present. Lignin solubility increased as temperature rose in the thermal solubility experiments. The rate of solubility increased 15 times for office paper and 1.5 times for cardboard in the biological experiments when compared to the thermal treatment. The thermal and biological study indicates that as lignin is solubilized, it breaks down into lignin monomers, which can be converted easily by anaerobic bacteria into VFAs and subsequently, methane. These experiments indicate that temperature is crucial to the degradation of lignin compounds in a bioreactor landfill. / Master of Science

Thesis advisor: Dunwei Wang / As an inedible component of biomass, lignin features rich functional groups that are desired for chemical syntheses. How to effectively depolymerize lignin without compromising the more valuable cellulose and hemicellulose has been a significant challenge. Existing biomass processing procedures either induce extensive condensation in lignin that greatly hinders its chemical utilization or focus on fully depolymerizing lignin to produce monomers that are difficult to separate for subsequent chemical synthesis. Here, we report a new approach to selective partial depolymerization, which produces oligomers that can be readily converted to chemically recyclable polymer networks. The process takes advantage of the high selectivity of photocatalytic activation of the β-O-4 bond in lignin by decatungstate catalysts (DT). In the photocatalytic system, DT works as both catalyst and oxidant, leading to two different reaction pathways, slow and steady bond cleavage pathway, and fast but limited oxidation pathway. The availability of exogenous electron mediators or external oxidants promotes cleavage or oxidation of this bond, respectively, enabling high degrees of control over the depolymerization and the stoichiometry of a key functional group, C═O, in the products. The resulting oligomers can then be readily utilized for the synthesis of polymer networks through reactions between C═O and branched −NH2 as a dynamic covalent cross-linker. Importantly, the resulting polymer network can be recycled to enable a circular economy of materials directly derived from biomass. / Thesis (PhD) — Boston College, 2024. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

After cellulose, lignin is the second most abundant natural polymer in the world. It has multiple functional groups, providing great potential for polymer production. In this project, we explored the use of this renewable and valuable resource in two different adhesive applications to displace petroleum-based additives, thereby providing a more sustainable and “green” product. In this regard, two types of lignin, water-soluble (Amalin LPH) and non-water-soluble lignin (Amalin HPH) provided by the British Columbia Research Institute (BCRI) were used. In the first case, lignin was added to a pressure-sensitive adhesive (PSA) formulation via in-situ seeded semi-batch emulsion polymerization. It was seen that lignin does not readily take part in the polymerization reaction; rather, its presence results in reaction inhibition. Therefore, Amalin LPH lignin was modified via acrylation to overcome this issue. In another modification approach, maleic anhydride was used to produce maleated Amalin HPH lignin. Both the acrylated and maleated lignins were used in butyl acrylate/methyl methacrylate emulsion copolymerizations to produce PSA films. A series of controlled experiments with different lignin loadings was conducted. Adhesive properties of the PSA films were measured and compared with the corresponding acrylic base case formulation. The incorporation of lignin in the PSA formulation was a “green” solution to conventional PSA production and led to a simultaneous increase in tack and shear strength. Further characterization of the latex films via transmission electron microscopy (TEM) showed that lignin was successfully incorporated into the polymer particles. It also showed that the use of maleated lignin at a higher concentration led to a core-shell morphology. In the second application, unmodified Amalin LPH lignin was used to create a starch-based adhesive through the Stein-Hall process, a two-step process involving a “carrier” portion and a “slurry” portion. Several formulations with lignin loadings up to 35 wt% distributed in varying ratios in the carrier and slurry portions were prepared. It was shown that the addition of lignin to the starch-based adhesive formulation increases the water-resistance of the adhesive. Therefore, lignin addition is a solution for a common issue in starch-based adhesives, their lack of water-resistance due to the high affinity of starch toward water. Lignin incorporation solely in the slurry portion significantly increased the strength of the glued joints in a paper board adhesive test. The use of lignin as a renewable replacement of petroleum-based components in two different adhesive formulations was demonstrated successfully. This research strongly suggests that lignin can be used as a high value-added property modifier in adhesive applications.

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Thesis (Ph. D.)--Institute of Paper Chemistry, 1942. / Includes bibliographical references (p. 68).

The use of fossil fuels is depleting the petroleum resources and the emissions exhausted during the use is contributing to the planets temperature rise, glaciers reciding and rised sea level etc. In a global perspective, the liquid petroleum fuels are dominating the fuel market. In the coming ten years, the use of liquid fuels is expected to grow.   In this work a method of preparing a biodiesel microemulsion between petroleum diesel and kraft lignin has been examined. Lignin is a renewable by-product from the pulp- and paper industry, extracted from black liquor. In its natural appearance, lignin is not soluble in water and has to be modified to work as the hydrophilic phase in the microemulsion. The modification is achieved in a oxidative ammonolysis process. As an indication of how well the modification is performing, the amount of dissolved lignin in water were measured. The influence by the reaction time, pH-value and water content on the amount of dissolved lignin were examined in a statistical model in the software MODDE. A screening examination was performed to find the most influential factors. The MODDE model was optimized and could thereafter be used as a predictive tool and predict the outcome of responses within the experimental range. Ultrasonication was used to create the microemulsion. A stabilization test was performed by observing the created lignin diesel samples during three weeks. The operational cost of producing lignin diesel was calculated based on the chemical cost and the cost of electricity consumed during the production process.   A microemulsion was not created between diesel and modified lignin, rather an emulsion was achieved. The highest amount of dissolved lignin in the oxidative ammonolysis process were 99.77 %. The most influential factor was the pH-value in the oxidative ammonolysis process. The water content also affected the amount of dissolved lignin, while the reaction time factor within its range did not affect the amount of dissolved lignin. The statistical model design, execution and predictive ability were evaluated in MODDE and given a satisfying grade. In the stability test, a separation in the bottom of the samples were observed after 0.5 h time. After one week, there was a small colour gradient in the top of one of the samples. After two weeks, the same colour gradient were observed in all of the samples. In none of the samples, a total phase separation was observed under the three weeks. / Användningen av fossila bränslen utarmar jordens petroleum resurser och under användning utsöndras emissioner som bland annat bidrar till den globala uppvärmningen, smältande glaciärer och höjda havsnivåer. Globalt sätt dominerar de flytande petroleum bränslena bränslemarknaden och dess användning förväntas inom de närmsta tio åren öka.   I detta examensarbete undersöks och testas en metod för framställning av lignindiesel. Lignindieseln består av petroleumdiesel och lignin, vilka hålls ihop med hjälp av en mikroemulsion. Lignin är en förnybar restprodukt från pappers- och massaindustrin som utvinns från svartlut. I naturligt utförande är lignin inte blandbart med vatten och behöver därför modifieras för att kunna agera som hydrofil fas i mikroemulsionen. Modifieringen görs genom en oxidativ ammonolysprocess. Som indikation på hur modifieringen verkade på ligninet mättes mängden löst lignin i vatten. Påverkan av faktorerna reaktionstid, pH-värde och vatteninnehåll på ligninets löslighet i vatten undersöktes i en statistisk modell som gjordes i programvaran MODDE. Den statistiska modellens design, utförande och predikteringskapacitet utvärderades. En screeningundersökning utfördes för att identifiera hur de olika faktorerna påverkade lignets löslighet i vatten. Modellen i MODDE optimerades och kunde därefter användas som en predikterande modell inom undersökningens omfattning. Ultraljudssonikering användes för att skapa mikroemulsionen. Ett stabiliseringstest gjordes genom att de olika lignindieslarna placerades i provrör som observerades under tre veckors tid. Driftkostnaden i form av kemikaliekostnad och kostnad för konsumerad elektricitet under produktionen beräknades.   En mikroemulsion kunde inte framställas. Dock skapades en emulsion mellan diesel och modifierat lignin. Den högsta halten av löst lignin i vatten var 99.77 %. pH-värdet under reaktionen var den faktor som påverkade ligninets löslighet mest. Vatteninnehållet i det modifierade ligninet påverkade också lösligheten samtidigt som reaktionstiden inte påverkade lösligheten nämnvärt inom det givna spannet. Den statistiska modellens design och utförande var tillfredställande och den prediktiva kapaciteten var mycket bra. Stabilitetstestet visade att en separation observerades i botten ett av lignindieselproverna efter 0.5 h. Efter en vecka observerades en liten färggradient i toppen av ett av provrören. Efter två veckor syntes samma sorts färggradient i alla lignindieselproverna. Inget av lignindieselproverna undergick fullständig fasseparation under the tre veckornas separationstest.

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