Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 27 for “"delignification"”.
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Delignification of wood with aqueous n-butanol solutions
Electronic Thesis or Dissertation
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The electrochemical mediation of oxygen delignification of pulp with a manganese polyol complex
… redox cycle did not significantly enhance the delignification or cellulose degradation reactions in factorial experiments at 20 °C or 90 °C. At 20 °C it is believed that increased peroxide stability prevented the delignification and cellulose degradation reactions. The formation of free radical …
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Delignification of Kraft-AQ Southern Pine Pulp with Hydrogen Peroxide Catalyzed by Mn(IV)2-Me4DTNE
… of a bleaching sequence. However, the degree of delignification achieved by a hydrogen peroxide stage is usually modest. That is because in alkaline condition the hydroperoxy anion reacts with chromophores in pulp as a nucleophile that does not oxidize residual lignin to a significant extent. In …
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Towards a comprehensive model for cooking processes
… mathematical models that describe the course of delignification and carbohydrate degradation during cooking processes as a function of cooking temperature and cooking chemicals concentrations. The cooking processes investigated in this work were the kraft and the autohydrolysis processes. In the …
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Pretreatment and hydrolysis of recovered fibre for ethanol production
… utilized for this research was oxygen delignification, which is a standard process stage in the production of bleached chemical pulp. The model substrate utilized as a feedstock for bioethanol was recovered fibre. An analysis of the substrates digestibility resulted in a hexose yield of …
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About the gel structure of lignin
… ether, and ethanol were subjected to acidolytic delignification treatments of increasing severity, and the lignin sol fractions were analyzed with regard to chemical structure and molecular architecture. Treatments with 0.2 N HCL in 90% aqueous dioxane ranged between 12 hr. at room temperature …
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Assessment of pre-treatment technologies for bio-ethanol production using multi-objective optimisation
… both acid and enzymatic hydrolysis. The use of delignification using sodium hydroxide prior to hydrolysis was investigated. The benefits of producing methane from the xylose-rich liquid leaving the pre-treatment unit were also included. The superstructure, which embeds the aforementioned …
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Evaluation of ligninolytic enzymes of (coptotermes curvignathus) gut bacteria for oil palm residues biodelignification
… research aims to identify alternative method for delignification by utilizing lignin degrading enzymes secreted by the termite gut bacteria, and also to explore the green delignification of oil palm residues for sustainable pulping. The lignin degrading bacteria (LDB) from the termite gut were …
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EVALUATION OF CELLULOLYTIC ENZYMES FROM A NEWLY ISOLATED BREVIBACILLUS SP. JXL; AND OPTIMIZATION OF COSLIF PRETREATMENT VARIABLES OF SWEET SORGHUM BAGASSE USING A RESPONSE SURFACE METHOD
… hydrolysis process. Accordingly, changes in delignification, total reducing sugar (TRS) yield, glucan retention, digestibility and overall sugar yields resulting from various combinations of reaction times and temperatures were determined. The results suggested that both pretreatment …
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Modeling Solvent Extraction of Lignin from Hardwoods
… sites for native lignin. The model simulates delignification as depolymerization of lignin macromolecules into fragments small enough to be soluble. This process competes with intrachain condensation that consumes labile bridges without forming new fragments, and with recombination that forms …
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Oil palm residue biodelignification by bacillus cereus ligninase from coptotermus curvignathus gut for handsheet production
… curvignathus gut’s bacteria was tested for biodelignification capability on palm oil biomasses: oil palm leaves (OPL), oil palm trunk (OPT) and empty fruit bunch (EFB). The biopulp was produced under submerged fermentation (SmF) using Luria Bertani (LB) broth at pH 6.5, 120 rpm and 37 °C for 7 …
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Electrochemically mediated oxygen bleaching of pulp
… generated ferricyanide increased the rate of delignification and cellulose degradation and gave a small increase in selectivity. As well, electrochemical oxygen bleaching provided milder operating conditions than employed in conventional oxygen bleaching. The highest selectivity in the …
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ΜΕΛΕΤΗ ΤΟΥ ΜΗΧΑΝΙΣΜΟΥ ΠΡΟΚΑΤΕΡΓΑΣΙΑΣ ΓΙΑ ΤΗΝ ΜΕΤΑΤΡΟΠΗ ΤΗΣ ΒΙΟΜΑΖΑΣ ΣΕ ΚΑΥΣΙΜΑ ΚΑΙ ΧΗΜΙΚΑ: ΕΠΙΔΡΑΣΗ ΣΤΗ ΣΤΕΡΕΑ ΦΑΣΗ
… THE CHEMICAL PRETREATMENTS UTILIZED WERE DELIGNIFICATIONS WITH AQUEOUS ALKALINE SOLUTIONS (NAOH, KOH, NA2CO3) AND ALCOHOL-WATER MIXTURES (METHANOL, ETHANOL, ISOPROPANOL, N-BUTANOL). THE EFFECT OF PRETREATMENTS ON THERMOCHEMICAL CONVERSION TO CHARCOAL, ON ENZYMIC HYDROLYSIS WITH ASPERGILLUS …
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ΠΑΡΑΓΩΓΗ ΧΑΡΤΟΜΑΖΑΣ ΑΠΟ ΑΧΥΡΟ ΜΕ ΤΗ ΜΕΘΟΔΟ ΟΞΥΓΟΝΟΥ
… ADVANTAGES OF THE ROLE OF OXYGEN AT THE STRAW DELIGNIFICATION STAGE WERE CLEARLY SHOWN PURE OXYGEN GAVE BEST RESULTS IN THE CASE OF UNTREATED STRAW, ON THE OTHER HAND AIR WAS FOUND BEST ON THE CASE OF PREHYDROLYSED STRAW. OPTIMAL RESULTS IN TERMS OF PULP YIELD AND KAPPA NUMBERS WERE GIVEN WHEN …
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Microbial Pretreatment of Cotton Stalks by Phanerochaete chrysosporium for Bioethanol Production
… were fair (R2=0.6133). Although significant delignification occurred during fungal pretreatment indicating the presence of ligninolytic enzymes, common spectrophotometric enzyme assays failed to detect lignin peroxidase (LiP) and manganese peroxidase (MnP) activities in fungal pretreatment …
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Supported Metalloporphines as novel and bioinspired Lignolytic Peroxidase-like Catalysts
Current, classical delignification processes are affected by some economical and environmental drawbacks. These approaches often seem to be inadequate, particularly in the perspective of a sustainable green process. Since immobilized metalloporphines can strictly emulate the active site of …
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Dynamic simulation of brown stock washers and bleach plants
… A linear relationship was derived to correlate delignification and brightening. Unit operation models for mixing, reactions and washing were formulated using mass balances on liquor, fibres, chromophores, chemicals, pH and dissolved solids. Bleaching kinetic models from the literature were …
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Application of bacterial ligninase enzymes from rynchophorus ferrugineus’s gut consortium in agropulp biodelignification
… in OPL and CG respectively, in which the highest delignification is obtained by the combination of all species. Furthermore, traces of small molecular weight compounds generated after the enzymatic breakdowns were identified through HPLC and GC-MS analysis as part of the complementary study. …
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Performance Assessment and Evaluation of Hydrophobic and Ultraviolet Protective Treatments for Historic Log Structures
… exposing untreated surfaces for further delignification and loss of fabric. Accelerated weathering was conducted using a QUV Weatherometer in the Architectural Conservation Laboratory (ACL) which simulates weathering by subjecting samples to cycles of UV-B light, heat, condensation, and …
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Two-stage acidic-alkaline pretreatment of Miscanthus for bioethanol production
… carried out lime pretreatment primarily for delignification. The process was optimized by using Response Surface Methodology (RSM) analysis taking account of temperature, catalyst loading and residence time. It was demonstrated that the maximized sugars yield could be attained at medium …
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