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dc.contributor.advisorWolcott, Michael P
dc.creatorJiang, Jinxue
dc.date.accessioned2017-06-19T16:20:12Z
dc.date.available2017-06-19T16:20:12Z
dc.date.issued2016
dc.identifier.urihttp://hdl.handle.net/2376/12006
dc.descriptionThesis (Ph.D.), Materials Science, Washington State Universityen_US
dc.description.abstractMechanical deconstruction offers a promising strategy to overcome biomass recalcitrance for facilitating enzymatic hydrolysis of pretreated substrates with zero chemicals input and presence of inhibitors. The goal of this dissertation research is to gain a more fundamental understanding on the impact of mechanical pretreatment on generating digestible micronized-wood and how the physicochemical characteristics influence the subsequent enzymatic hydrolysis of micronized wood. The initial moisture content of feedstock was found to be the key factor affecting the development of physical features and enzymatic hydrolysis of micronized wood. Lower moisture content resulted in much rounder particles with lower crystallinity, while higher moisture content resulted in the milled particles with larger aspect ratio and crystallinity. The enzymatic hydrolysis of micronized wood was improved as collectively increasing surface area (i.e., reducing particle size and aspect ratio) and decreasing crystallinity during mechanical milling pretreatment. Energy efficiency analysis demonstrated that low-moisture content feedstock with multi-step milling process would contribute to cost-effectiveness of mechanical pretreatment for achieving more than 70% of total sugars conversion. In the early stage of mechanical pretreatment, the types of cell fractures were distinguished by the initial moisture contents of wood, leading to interwall fracture at the middle lamella region for low moisture content samples and intrawall fracture at the inner cell wall for high moisture content samples. The changes in cell wall fractures also resulted in difference in the distribution of surface chemical composition and energy required for milling process. In an effort to exploit the underlying mechanism associated with the reduced recalcitrance in micronized wood, we reported the increased enzymatic sugar yield and correspondingly structural and accessible properties of micronized feedstock. Electronic microscopy analysis detailed the structural alternation of cell wall during mechanical process, including cell fracture and delamination, ultrastructure disintegration, and cell wall fragments amorphization, as coincident with the particle size reduction. It was confirmed with Simons’ staining that longer milling time resulted in increased substrate accessibility and porosity. The changes in cellulose molecular structure with respect to degree of polymerization (DP) and crystallinity index (CrI) also benefited to decreasing recalcitrance and facilitating enzymatic hydrolysis of micronized wood.en_US
dc.description.sponsorshipWashington State University, Materials Scienceen_US
dc.language.isoEnglish
dc.rightsIn copyright
dc.rightsPublicly accessible
dc.rightsopenAccess
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/
dc.rights.urihttp://www.ndltd.org/standards/metadata
dc.rights.urihttp://purl.org/eprint/accessRights/OpenAccess
dc.subjectMaterials Scienceen_US
dc.subjectWood sciencesen_US
dc.subjectAccessibilityen_US
dc.subjectCell wallen_US
dc.subjectEnzymatic hydrolysisen_US
dc.subjectMechanical deconstructionen_US
dc.subjectSoftwooden_US
dc.subjectUltrastructureen_US
dc.titleASSESSING MECHANICAL DECONSTRUCTION OF SOFTWOOD CELL WALL FOR CELLULOSIC BIOFUELS PRODUCTION
dc.typeText
dc.typeElectronic Thesis or Dissertation


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