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Madikane, Mzekelo. "Biosulphidogenic hydrolysis of lignin and lignin model compounds." Thesis, Rhodes University, 2002. http://hdl.handle.net/10962/d1003976.
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Lignin degradation under biosulphidogenic conditions has not been extensively reported in the literature. Although aerobic degradation of lignin is well documented, anaerobic biodegradation has focused mainly on methanogenic systems with biosulphidogenic systems receiving less attention. Sulphate reducing bacteria are known to generate moderately high levels of both sulphide and alkalinity at room temperatures, and these conditions draw some comparison with the Kraft pulping process. In the Kraft pulping process, lignin is degraded chemically at ±170°C under high sulphide and alkaline conditions and may provide a model for understanding biosulphidogenic lignin degrading activity. The aim of this study was to investigate the biosulphidogenic hydrolysis of lignin within the context of the chemical and biological conditions generated by a mixed sulphate reducing bacteria consortia. Bioreactor studies with a mixed sulphate reducing consortia and pine wood powder (both untreated and depectinated) resulted in the generation of comparable levels of sulphide and alkalinity used in the chemical hydrolysis studies. Aromatic compound yields were between 20 to 50% of the chemical hydrolysis studies. This fluctuation may have been due to the utilization of these aromatic compounds as electron donors by the sulphate reducing consortia as evidenced by the high rate of sulphate reduction in both the untreated and depectinated wood bioreactors. Biodegradation of lignin model compounds was investigated in order to elucidate lignin degradation mechanisms. Both mono-aromatic and dimeric lignin model compounds were used as electron donors and carbon sources for the mixed sulphate reducing consortia. Biodegradation and mass spectrometer analysis of mono-aromatic compounds, ferulic acid and ferulic acid ethyl ester resulted in the production of intermediates such as catechol, cyclohexane carboxylic acid and adipic acid. These intermediates were also observed in the degradation of dimeric ferulic acid. Biodegradation of salicin resulted in the production of salicyl alcohol, ortho-cresol and acetate. Biodegradation of benzylic ether resulted in the production of vanillin and acetate as end products. The results of these studies provide evidence for a biosulphidogenic hydrolysis of lignin, and also the utilisation of lignin-derived aromatic compounds as electron donor sources, by a mixed sulphate reducing consortia.
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Betts, Walter B. "Microbial degradation of lignin and lignin related aromatic compounds." Thesis, Loughborough University, 1987. https://dspace.lboro.ac.uk/2134/12210.
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Galkin, Maxim. "Palladium-catalyzed lignin valorization : Towards a lignin-based biorefinery." Doctoral thesis, Uppsala universitet, Syntetisk organisk kemi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-265315.
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The work described in this thesis focuses on the cleavage of the β-O-4′ bond, which is the most abundant interunit linkage in the lignin polymer. In the first part, three methods based on palladium catalysis have been developed and their applicability has been verified using lignin model compounds. A transfer hydrogenolysis of the β-O-4′ bond using formic acid as a mild hydrogen donor together with a base. An aerobic oxidation of the benzylic alcohol motif in the β-O-4′ linkage to generate a key intermediate in the cleavage reaction was performed. A redox neutral cleavage of the β-O-4′ bond was accomplished in which no stoichiometric reducing or oxidizing agents were added. In the second part of the thesis, a mechanistic study is presented. The corresponding ketone from a dehydrogenation reaction of the benzylic alcohol motif was identified to be the key intermediate. This ketone and its enol tautomer was found to be responsible for the β-O-4′ bond cleavage reaction under the employed reaction conditions. In the final part of this thesis, the methodologies have been applied to native lignin. The depolymerization reaction was combined with organosolv pulping. This approach was successful, and together with cellulose and hemicellulose, propenyl aryls were generated in excellent yields directly from wood. In this transformation, the lignin derived molecules have been reduced by an endogenous hydrogen donor from the wood.
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Johal, Amrit. "Chemicals from lignin." Thesis, University of Nottingham, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.716671.
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This Thesis investigates the production of high-value chemicals, such as vanillin and guaiacol, by the decomposition and oxidation of lignin in high temperature water. Currently, there is significant global interest in developing chemical production methods that utilise biorenewable feedstocks in place of crude oil and natural gas. Lignin, a complex set of biopolymers found in wood, straw and similar plant materials, is a viable biorenewable raw material for the production of aromatic chemicals. However, currently lignin is mostly used as a low-value fuel in pulp mills. Chapter 1 highlights the concerns that have led to the current demand for greater utilisation of biomass. In that respect, the potential uses of lignin are described. Supercritical water is discussed in relation to green chemistry and specifically as a medium for carrying out oxidation reactions on methyl aromatics. The equipment and methodology used for carrying out experiments and the instruments used for product analysis are described in Chapter 2. Preliminary work that was carried out is described in Chapter 3. These experiments look at the stabilities and oxidation of monomeric aromatic aldehydes, acids and phenols in high temperature water. These substrates each contained either a p-hydroxyphenyl, guaiacyl or syringyl unit. The work in Chapter 4 examined the use of metal bromides and hydrobromic acid as catalysts in the oxidation of three lignin model compounds; 2-methoxy-4-methylphenol, 4-ethyl-2-methoxyphenol and eugenol. These reactions were performed in the near-critical to supercritical region of water. Lignin samples from both Kraft pulping and sulfite pulping sources were shown to breakdown to vanillin, vanillic acid and guaiacol through oxidative treatment in a high temperature water continuous-flow reactor. This work is described in Chapter 5. The overall conclusions of this Thesis are summarised in Chapter 6.
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Kvainauskas, Darius, and Martin Johansson. "Biodrivmedel från lignin." Thesis, KTH, Skolan för industriell teknik och management (ITM), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-232835.
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Lignin är en molekyl som finns i alla växter och kan användas för att framställa nya generationens biodrivmedel. Ligninbaserade biodrivmedel är bra från en miljöaspekt för att det minskar växthuseffekten, men också för att utvinningen av svartlut kan effektivisera tillverkning av pappersmassa. Vid tillverkning av massa fås en restprodukt vid namnet svartlut. Svartlut har ett högt energiinnehåll och kan vara ganska besvärlig att hantera. Det kan användas till värme eller energi internt i massabruken, men fås ofta i större mängder än massa- och pappersbrukens sodapannor kan ta hand om. Det är från svartlut som lignin kan utvinnas. Idag finns det processer som bland annat LignoBoost som utvinner lignin från svartlut. Lignin behöver därefter omvandlas till en flytande form för att sedan blandas in som en komponent i bensin och diesel. Detta kandidatexamensarbete utforskar möjligheter att använda svartlut för utvinning av lignin till ligninbaserade biobränslen. Utöver det har hela råvaruflödet av lignin kartlagts. Kartläggningen av råvaruflödet har utförts med hjälp av en litteraturstudie och intervjuer. Vidare har uppskattningar gjorts på hur stor del av energianvändningen i transportsektorn som kan ersättas med energi från lignin. Energipotentialen från ligninet har baserats på tre olika fall där olika stora andelar av det tillgängliga ligninet används. För Fall 2, där 50% av ligninet utvinns, beräknades även kostnaden för en energikälla (skogsflis) som kan ersätta den energi i svartlutet som annars används som bränsle i massa- och pappersbruken. Från litteraturstudien och intervjuerna är slutsatsen att det i nuläget inte finns ett färdigt råvaruflöde för lignin, däremot är det tre steg som behöver gå ihop för att ett fungerande råvaruflöde ska skapas; utvinning av lignin, omvandling till flytande lignin och distribution. Samtliga aktörer i detta råvaruflöde behöver samarbeta för att hitta en lösning alla kan dra fördel av och subventioner kan behövas för att drivmedlet ska ha ett rimligt pris. Resultatet visar att det finns 3,1 miljoner ton lignin tillgängligt under ett års tid från massa- och pappersbruken i Sverige. Från detta lignin är energipotentialen 12,81 TWh ifall det antas att 30% av allt svartlut används. Detta motsvarar 13,6 % av energibehovet i transportsektorn och räcker till bränsle för 1,56 miljoner personbilar årligen. Ifall 50 % av svartluten används är energipotentialen 21,34 TWh, vilket motsvarar 22,7 % av energibehovet i transportsektorn. I detta fall skulle 25 miljoner ton trädbränsle behöva användas för att ersätta energin, med ett beräknat pris på 1,56 miljarder SEK.Lignin is a molecule found in all plants and can be used to produce new generation biofuels. Lignin-based biofuels are beneficial from an environmental aspect because they help to reduce the greenhouse effect, but also because the extraction of black liquor can streamline the production of pulp. In the manufacturing process of pulp, a residual product is obtained by the name of black liquor. Black liquor has a high energy content and can be quite difficult to handle after extraction. It can be used for heat or energy internally in the pulp mill, but it is often available in larger quantities than infrastructure at the pulp- and paper mills can handle. It is from black liquor that lignin can be extracted. Today, there are processes such as LignoBoost that extract lignin from black liquors. The lignin then needs to be converted into a liquid form and then mixed as a component of gasoline and diesel. This Bachelor's Degree Project explores the possibilities of using black liquor and making ligninbased biofuels. In addition, the entire raw material flow of lignin has been mapped. The mapping of the raw material flow has been carried out using a literature study and interviews. Furthermore, estimates have been made of how much of the energy consumption in the transport sector that can be replaced by the energy that is obtainable from lignin. The energy potential of the lignin is based on three different cases, with different proportions of available lignin. For Case 2, where 50% of the lignin is recovered, the cost of a replacement source (wood chips) is also calculated. This energy source can replace the energy in black liquor that is used as fuel in the pulp- and paper mills. From the literature study and the interviews, it is concluded that there is currently no raw material flow for lignin, but there are three steps that need to work together to create a functioning one; recovery of lignin, conversion into liquid lignin and distribution to consumers. All stakeholders in this raw material flow need to work together to find a solution everyone can benefit from and subsidies may be needed for the fuel to have a reasonable price. The result shows that there are 3.1 million tonnes of lignin available for one year from pulp and paper mills in Sweden. From this lignin the energy potential is 12.81 TWh if it is assumed that 30% of all black liquor is used, which is equivalent to the energy used by 1.56 million cars. This corresponds to 13.6% of the energy demand in the transport sector. If 50% of the black liquor is used, the energy potential is 21.34 TWh, which corresponds to 22.7% of the energy demand in the transport sector. In this case, 25 million tons of wood fuel would need to be used to replace energy, which costs 1.56 billion SEK.
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Nakatsubo, Tomoyuki. "Characterization of O-methyltransferases and pinoresinol reductases involved in lignin and lignan biosynthesis." Kyoto University, 2008. http://hdl.handle.net/2433/123964.
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Kyoto University (京都大学)0048
新制・課程博士
博士(農学)
甲第14173号
農博第1734号
新制||農||964(附属図書館)
学位論文||H20||N4412(農学部図書室)
UT51-2008-N490
京都大学大学院農学研究科応用生命科学専攻
(主査)教授 梅澤 俊明, 教授 宮川 恒, 教授 矢﨑 一史
学位規則第4条第1項該当
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Dodson, A. P. J. "The use of lignin peroxidases to degrade lignin in plant cell walls." Thesis, Imperial College London, 1991. http://hdl.handle.net/10044/1/46747.
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Tan, Xin. "Effect of Organosolv Lignin and Extractable Lignin on Enzymatic Hydrolysis of Lignocelluloses." University of Cincinnati / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1613752000022518.
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Jennings, John Adam. "HETEROGENEOUS BASE METAL CATALYZED OXIDATIVE DEPOLYMERIZATION OF LIGNIN AND LIGNIN MODEL COMPOUNDS." UKnowledge, 2017. http://uknowledge.uky.edu/chemistry_etds/81.
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With the dwindling availability of petroleum, focus has shifted to renewable energy sources such as lignocellulosic biomass. Lignocellulosic biomass is composed of three main constituents, lignin, cellulose and hemicellulose. Due to the low value of cellulosic ethanol, utilization of the lignin component is necessary for the realization of an economically sustainable biorefinery model. Once depolymerized, lignin has the potential to replace petroleum-derived molecules used as bulk and specialty aromatic chemicals. Numerous lignin depolymerization strategies focus on cleavage of β-aryl ether linkages, usually at high temperatures and under reductive conditions.
Alternatively, selective benzylic oxidation strategies have recently been explored for lignin and lignin models. In this work, heterogeneous catalytic methods using supported base metals and layered-double hydroxides were evaluated for the oxidation of lignin models both before and after benzylic oxidation. Additionally, by studying putative reaction intermediates, insights were gained into the mechanisms of oxidative fragmentation of the model compounds.
Generally, it was found that after benzylic oxidation models were more susceptible to oxidative fragmentation. Indeed, several heterogeneous oxidation systems were found to convert lignin models to oxygenated aryl monomers (mainly benzoic acids and phenols) using inexpensive primary oxidants (i.e., hydrogen peroxide and molecular oxygen). Reactions were conducted at relatively mild temperatures and at low oxygen concentrations for the purpose of an easy transition to large-scale experiments. Finally, the catalytic systems that resulted in significant cleavage of lignin models were applied to a Kraft lignin. Oxidation of Kraft lignin resulted a mixture of products for which analytical data and increased solubility are consistent with interunit cleavage within the lignin macromolecule.
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Dodge, Luke A. "FRACTIONATION OF LIGNIN DERIVED COMPOUNDS FROM THERMOCHEMICALLY PROCESSED LIGNIN TOWARDS ANTIMICROBIAL PROPERTIES." UKnowledge, 2018. https://uknowledge.uky.edu/bae_etds/54.
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The overuse of antibiotics in agriculture is an emerging concern, due to their potential detrimental impact to the environment. This study focuses on exploring antimicrobial properties of lignin derived compounds. Lignin is of interest as a feedstock to replacing some petroleum-based chemicals and products because it is the most abundant source of renewable aromatic compounds on the planet. Two lignin rich streams, residues from the enzymatic hydrolysis of dilute acid and alkaline pretreated corn stover, were decomposed via pyrolysis and hydrogenolysis, respectively. The resulting liquid oils were subjected to sequential extractions using a series of solvents with different polarities. Chemical compositions of the extracted fractions were characterized through HPLC and GC/MS. These extracted compounds were screened against Saccharomyces cerevisiae (S. cerevisiae), Escherichia coli, and Lactobacillus amylovorus for antimicrobial properties. Six lignin model monomers: guaiacol, vanillin, vanillic acid, syringaldehyde, 2,6-dimethoxyphenol, and syringic acid were compared to the oils and extracted fractions for antimicrobial properties. Development of lignin-derived chemicals with antimicrobial properties could provide a novel use for this underutilized natural resource.
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Luo, Jie. "Lignin-Based Carbon Fiber." Fogler Library, University of Maine, 2010. http://www.library.umaine.edu/theses/pdf/LuoJ2010.pdf.
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Houssain, Feroza. "Inhibitors of lignin peroxidase." Thesis, Imperial College London, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283289.
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Camargo, Francisco Adão de. "Obtenção e caracterização das blendas de ligninas (sulfonadas, bagaço de cana de açucar, eucalipto) e taninos com o poli(3-hidroxibutirato-co-3-hidroxivalerato)/PHBV." [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/267094.
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Orientadores: Lucia Helena Innocentini Mei, Nelson Eduardo Duran CaballeroTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica
Made available in DSpace on 2018-08-13T07:57:38Z (GMT). No. of bitstreams: 1 Camargo_FranciscoAdaode_D.pdf: 5687735 bytes, checksum: 30f309fc3c8612bce1b126f965cd65a9 (MD5) Previous issue date: 2009
Resumo: A produção de plásticos sintéticos tem aumentado ano após ano, por ser barato, resistente, etc. Mas, os especialistas advertem que o lucro obtido na industrialização e comercialização dos plásticos não pode por em risco o futuro da humanidade. Os fatos demonstram que o planeta já foi prejudicado, principalmente a fauna e a flora marinha. A solução para este problema é o desenvolvimento de materiais biodegradáveis, que garantam um desenvolvimento sustentável, onde o homem e o meio possam conviver sem causar prejuízos entre si. Com este princípio, buscamos neste trabalho o desenvolvimento de blendas biodegradáveis de polímeros naturais, com potencial para substituir alguns dos plásticos convencionais, contribuindo para o binômio produção versus preservação ambiental. A lignina é uma biomacromolécula, assim como o tanino, os quais são disponíveis em grande quantidade no Brasil. O outro componente da blenda, o copolímero de poli(3- hidroxibutirato-co-3-hidroxivalerato) ou PHBV, é uma biomolécula, termoplástico natural, biodegradável e biocompatível. Foi escolhida esta proporção (50:50)% (m/m), esta proporção foi a proporção estudada anteriormente, para a blenda de lignina de bagaço de cana com o PHBV, no aparelho Haake. Os estudos das propriedades mecânicas mostraram boas características de resistência, sendo processada na extrusora dupla rosca e injetada para a confecção dos corpos de prova. Foi estudada a biodegradação das amostras, em meio sólido, por ação dos fungos e bactérias do solo. As caracterizações das blendas (50:50) %, (m/m), ligninas, taninos, PHBV e PHB foram feitas por: Infravermelho com Transformada de Fourier (FT-IR), Calorimetria Diferencial de Varredura (DSC), Análise Dinâmico Mecânica (DMA), Microscopia Eletrônica de Varredura (MEV), Análise Elementar (CHN), Espectroscopia de Fluorescência, Fluorescência de Raios-X e Ressonância Magnética Nuclear de Hidrogênio (RMN- 1H).
Abstract: The production of synthetic plastics has been increasing year after year, for being cheap, resistant, and soon however, the specialists notice that the profit obtained in the industrialization and commercialization of the plastics should not put in risk the Humanity's future. The facts demonstrate that the planet was already harmed, mainly the fauna and the sea flora. The solution for this problem is the development of biodegradable materials to guarantee a sustained development, where the man and the environment have together without causing damages amongst themselves. With this objective, we decided to study in this work the development of biodegradable blends of natural polymer, with potential to substitute some of the conventional plastics, contributing thus the binomial production versus environmental preservation. The lignin is a biomacromolecule, as well as the tannin, theses components are available in great amount in the tropical countries like Brazil. The other component of the blends, the copolymer of poly(3-hydroxybutirate-co-3-hydroxyvalerate) or PHBV, is a natural biomolecule, thermoplastic, biodegradable and biocompatible. It was chosen this proportion (50:50) % (w/w), also this proportion was studied previously in our research group, for the blend of lignin of sugar cane bagasse with PHBV, in the apparatus Haake. The studies of mechanical properties because showed good resistance characteristics. The blends were processed in the twin screw extruders and injected for the making of the test sample. It was studied the biodegradation of the samples, in solid medium, in presence of the fungi and bacteria of the soil. The characterization of blends (50:50%) (w/w), lignins, tannins, PHBV's and PHB's were made by: Fourier Transform Infrared (FT-IR), Differential Scanning Calorimetry (DSC), Dynamic Mechanical Analysis (DMA), Scanning Microscopy Electronic (SEM), Elementary Analysis (CHN), Spectroscopy of Fluorescence, Fluorescence of ray-X and Nuclear Magnetic Resonance of Hydrogen (NMR -1H).
Doutorado
Ciencia e Tecnologia de Materiais
Doutor em Engenharia Química
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Rinesch, Torsten [Verfasser]. "Oxidative Spaltung von Lignin und Lignin-Modellverbindungen und Funktionalisierung der Spaltprodukte / Torsten Rinesch." München : Verlag Dr. Hut, 2019. http://d-nb.info/1181514312/34.
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Bacha, Carolina Barbosa. "Determinação do teor de lignina em amostras de gramíneas ao longo do crescimento através de três métodos analíticos e implicações com as equações de ″Cornell Net Carboydrate and Protein System″." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/10/10135/tde-12012007-163126/.
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Quantificou-se o teor de lignina em cinco amostras de plantas forrageiras, nas frações caule e folha, em quatro estádios de maturidade, através de três métodos analíticos: lignina detergente ácido (LDA), lignina permanganato de potássio (LPer) e lignina Klason (LK), todos de natureza gravimétrica. Os três métodos não foram concordantes entre si, sendo que para a maioria das amostras, o método LK mostrou valores mais elevados que os outros dois métodos, e o método LDA exibindo os menores valores. A fração caule exibiu teores mais elevados de lignina do que a folha; forrageiras maduras mostraram maiores concentrações de lignina do que plantas mais novas. Para quase todas as amostras, a digestibilidade in vitro da matéria seca foi negativamente correlacionada com os teores de lignina estimados pelos três métodos analíticos. O método LDA estimou razoavelmente bem a digestibilidade de forrageiras, seguindo-se a LPer. A LK não estimou bem a digestibilidade de gramíneas. Conclui-se que, nenhum dos três métodos foi totalmente satisfatório, sugerindo que a determinação analítica da lignina seja mais profundamente estudada. Este trabalho também quantificou as frações de carboidratos pelas equações da ″Cornell Net Carbohydrate and Protein System (CNCPS)″. A utilização da preparação parede celular (PC) nas equações da CNCPS, em substituição à fibra em detergente neutro (FDN), não proporcionou diferenças quanto aos teores de carboidratos de todas as frações. Porque foi realizada a comparação entre PC e FDN, foi descoberto que a equação da fração C, que estima os carboidratos indigeríveis da parede celular, pode ser simplificada, relacionando a fração indigerível em função do teor de lignina na matéria seca, e não em função da FDN, como é atualmente amplamente utilizado. Em outras palavras, o cálculo da fração indigerível da parede celular pode ser obtido independentemente da FDN isenta de cinzas e proteína. Como os valores da fração B1 (amido e pectina) pelo sistema CNCPS foram menores em relação à determinação laboratorial e com base nos resultados obtidos pelo emprego da PC nas equações de Cornell, sugere-se que a fração B2 seja destinada exclusivamente à pectina. E para os carboidratos digeríveis da parede celular, uma nova fração seja denominada, a B3 . Evidências colhidas na presente pesquisa sugerem que, pelas equações de Cornell, a pectina nunca esteve presente na fração B1 e sim na fração A. Portanto, do conteúdo da fração A, dever-se-ia subtrair o valor da pectina. A fração C continuaria inalterada e a fração B1 seria constituída apenas de amidoLignin was quantified in five forage samples, in the fractions stem and leaf, at four maturity stages, through three analytical methods: acid detergent lignin (ADL), permanganate lignin (PerL) and Klason lignin (KL), all gravimetric procedures. The three techniques yielded different values for the same samples; in general, the KL method showed higher lignin concentrations than the two other methods, being the ADL which showed the lowest data. Stem fraction exhibited higher levels of lignin than leaf tissue; mature forages had higher concentrations of lignin than younger plants. For almost all the samples, lignin concentration was negatively correlated with the in vitro dry matter digestibility. The method ADL estimated reasonably well the digestibility of grasses, followed by PerL. The KL method was not a good predictor of digestibility of grasses. It was concluded that none of the three methods was totally satisfactory, suggesting that the analytical determination of lignin should be more deeply studied. This work also quantified the carbohydrate fractions through the Cornell Net Carbohydrate and Protein System (CNCPS). The utilization of crude cell wall instead of neutral detergent fiber in the CNCPS equations showed no differences in the estimates of all carbohydrate fractions. Because it was made a comparison between CW and NDF, it was discovered that the equation for the fraction C could be simplified where lignin expressed as a ratio of NDF, could be described on dry matter basis and not on NDF basis as it is largely used nowadays. In another words, estimate of indigestible cell wall could be obtained independently of ash + protein-free NDF. Because estimates of B1 fraction (starch and pectin) by means of CNCPS equations were lower than wet chemistry determinations and based on the results obtained by the substitution of NDF for PC in the Cornell equations, we suggest that B2 fraction be allocated exclusively for pectin. And for the digestible cell wall carbohydrates a new fraction, B3, be named. Evidences collected in the present experiment suggest that in the Cornell equations pectin was never part of B1 fraction but present in the A fraction. Thus, from the content of fraction A, pectin must be subtracted. The fraction C would remain unaltered and the fraction B1 would be constituted only by starch
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Fuzeto, Adriana Paula. "Determinação do teor de lignina em amostras vegetais através de três métodos analíticos e correlação com digestibilidade in vitro." Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/10/10135/tde-17092007-165756/.
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A digestibilidade in vitro da matéria seca e da parede celular, de diferentes amostras vegetais arranjadas em três grupos: forragens, madeiras ou bambus, foi correlacionada com os teores de lignia estimados por três métodos analíticos. Os métodos empregados foram: lígnina em detergente ácido (LDA). lignina Klason (LK) e lignina permanganato de potássio (LPer). Os teores de lignina foram diferentes entre os métodos, para as mesmas amostras analisadas, sendo no geral maiores para LK e LPer. Para quase todas as amostras, os teores de lignina foram negativamente correlacionadas com a digestibilidade in vitro da matéria seca e da parede celular. O método LDA estimou razoavelmente bem a digestibilidade de forrageiras e bambus, seguindo-se a LPer. A LK não estimou bem a digestibilidade de gramíneas. Quanto às madeiras, nenhum dos três métodos foi um bom indicador da digestibilidade, mesmo o método LK, tradicionalmente usado para madeiras. Conclui-se que, nenhum dos três métodos foi totalmente satisfatório, sugerindo que a determinação analítica da lignina seja mais profundamente estudada.The in vitro digestibility either dry matter or cell wall of different vegetable samples arranged in three groups: forages, wood or bamboos was correlated with lignin concentration determined through three analytical methods. The employed methods were: acid detergent lignin (ADL), Klason lignin (KL) and potassium permanganate lignin (PerL). Lignin concentrations were different among the methods for the same samples, generally larger for KL and PerL. For almost all samples, lignin concentration was negatively correlated with in vitro digestibility of dry matter and cell wall. ADL method predicted digestibility of grasses and bamboos reasonably well, followed by PerL. KL content was not a good predictor of grass digestibility. Concerning woods, none of the three methods was a good predictor of digestibilty, even the KL method, traditionally used for wood. It is concluded that none of the three methods was totally satisfactory, suggesting that analytical determination of lignin needs more research effort.
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la, Placa Antonia. "Comparison of Miscanthus grass lignin with spruce lignin from organosolv process for nanoparticles production." Thesis, KTH, Skolan för kemi, bioteknologi och hälsa (CBH), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-278835.
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There is a growing global energy demand and the society is forced to shift towards renewable energy sources due to the depletion of fossil fuels. Lignocellulosic biomass is a renewable resource available in vast amounts and could therefore have the potential to become a primary source for fuel production. Lignin, as a substantial part of the biomass, is underutilized due to its complex structure which can limit the potential of applying lignin towards value- adding products. However, one way to promote lignin valorization is to produce lignin nanoparticles (LNPs) that are considered valuable in the biomedical field. The aim of this report was to investigate if different botanical origins will affect the properties of LNPs, such as size, polydispersity index, 𝜁-potential and morphology. LNPs from Miscanthus sinensis grass lignin, obtained by the organosolv process, was successfully produced via solvent exchange and compared with LNPs from spruce organosolv lignin. The experimental part resulted in Miscanthus LNPs ranging from 133.7 to 377.4 nm, where a higher initial concentration yielded larger particles, and the average ζ- potential was -38.7 mV. This work has shown that the botanical origin will affect both size and shape of LNPs produced with the same method. Miscanthus LNPs were larger in size and ellipsoidal in shape compared to the spherical spruce LNPs. The lignin concentration influenced the particle size for both origins and the difference in LNP size became more significant as the concentration increased. However, to only explore two different types of plant origins is not sufficient enough to reach a general conclusion. Also, there are many influential steps from plant origin to LNP and to reach a more generalized conclusion, it is arguable that there is a necessity to explore and determine both the applied pulping method, the process to isolate the lignin and the method used to produce the LNPs.Det globala energibehovet ökar och samhället tvingas därmed att växla till förnybara resurser eftersom de fossila bränslena kan ta slut. Biomassa är en förnybar resurs som finns tillgänglig i stora mängder och kan därför bli en potentiell primär energikälla. Lignin, som är en väsentlig del av biomassan, används inte i lika stor utsträckning på grund av dess komplexa struktur. Komplexiteten begränsar därför användandet av lignin i värdeskapande produkter. Men en väg för att ta tillvara på lignins värdefulla egenskaper kan vara framställandet av nanopartiklar (NP), vilket öppnar upp för användning av lignin inom det biomedicinska fältet. Syftet med den här rapporten är att undersöka om lignin från olika botaniska ursprung påverkar nanopartiklarnas egenskaper, som exempelvis storlek, polydispersitet, 𝜁-potential och morfologi. NP av lignin från gräsarten Miscanthus sinensis framställdes genom solvent exchange och jämfördes sedan med NP från granlignin. Både miscanthus- och granligninet var isolerat genom organosolvprocessen. Den experimentella delen av arbetet visade att NP from miscanthuslignin gav partiklar inom intervallet 133.7 to 377.4 nm, där högre koncentration gav större partiklar, och medelvärdet för 𝜁-potentialen var -38.7 mV. Resultatet från arbetet visade att det botaniskt ursprunget påverkar både storleken och formen på NP av lignin som framställts med samma metod. NP från miscanthuslignin var större och hade en mer elliptisk form, i jämförelse med de mer sfäriska partiklarna från granlignin. Ligninkoncentrationen påverkade partikelstorleken för båda typerna av lignin, dessutom blev skillnaden i partikelstorlek större när koncentrationen ökade. Däremot var det svårt att dra någon generell slutsats genom att bara undersöka två olika ursprung. Eftersom det finns flera steg i processen från växters ursprung till NP av lignin som kan påverka partiklarnas egenskaper kan det vara nödvändigt att utforska både den tillämpade massaprocessen, isoleringsmetoden och metoden som används för att framställa NP av lignin.
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Wessén, Anna, Eliot Diklev, and Lejla Al-Tamimi. "Development of magnetic lignin nanoparticles from low-molecular-weight eucalyptus and spruce lignin fractions." Thesis, KTH, Skolan för kemi, bioteknologi och hälsa (CBH), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-277112.
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Lignin is one of the most common biopolymers in the world. Together with cellulose andhemicellulose it constitutes the fibers in the wood. It has a high molecular weight due to its complexstructure consisting of crossed-linked phenolic monomers and is concatenated with different types ofcarbon and ether bonds.In pulping processes, lignin is extracted in large quantities and used on site to produce energy for milloperations but is also removed as a waste product. This enables a product with high resources andaccessibility due to lignin's diverse properties. Therefore, lignin has the potential to be utilized inhigher value applications such as polymer materials, as well as a source of platform chemicals. Atpresent, the value applications of lignin are promising as additives for different kinds of productssuch as emulsifiers and especially as biofuel due to lignin's high carbon content.New technologies for development for utilization lignin are emerging for different kinds ofapplications due to lignin’s biocompatibility. The possibilities of lignin combined with existingresearch of nanotechnology gives opportunities to improve biomedical applications. By designinglignin derived nanoparticles with incorporated magnetic materials, the NPs obtainsuperparamagnetic properties which can be utilized for target drug delivery. This could be promisingagainst intractable cancer such as pancreatic cancer.This report presents a protocol for developing magnetic lignin nanoparticles from the lowestmolecular weight kraft lignin fractions of eucalyptus (hardwood) and spruce (softwood). By a methodof self-assembly, particles with a doughnut and core-shell morphology, as indicated by SEM and TEM,were yielded with a 10-50μL content of water-stabilized magnetite. The particle size distribution andzeta potential were determined by DLS and the possibility of the particles being suitable forbiomedical applications was discussed.
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Ämmälahti, Erja. "Application of NMR spectroscopy to structural studies of lignin /." Espoo [Finland] : Technical Research Centre of Finland, 1999. http://www.inf.vtt.fi/pdf/publications/1999/P395.pdf.
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Nieh, Li-Shih World. "Synthesis and properties of lignin epoxide." Thesis, Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/101357.
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A lignin epoxide resin was synthesized and characterized.
The epoxidation reaction was studied by reacting hydroxypropylated guaiacol (a lignin-like model compound) and epichlorohydrin using a catalyst system of potassium hydroxide and a phase transfer catalyst in toluene. The parameters studied were different epichlorohydrin level and temperature. The reaction was followed by HPLC and the structure of the product was identified with IR, ¹H and ¹³C NMR spectroscopy.
The lignin epoxide was synthesized by reacting hydroxyalkylated (hydroxypropyl and hydroxybutyl) lignin with epichlorohydrin using the reaction conditions defined by the model compound studies. The reaction was studied at different epichlorohydrin level and at elevated and room temperature. The epoxy content of the lignin epoxide was determined by titration with HBr and its structure was identified with IR, ¹H and ¹³C NMR spectroscopy.
Lignin epoxides were cured by crosslinking with a diamine and with phthalic anhydride. An amine-terminated rubber was added as toughening agent. Sol fraction and swelling behavior, stress-strain behavior and dynamic mechanical behavior of the cured lignin epoxides were studied in relation to cure conditions.M.S.
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Norberg, Ida. "Carbon Fibres from Kraft Lignin." Doctoral thesis, KTH, Träkemi och massateknologi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-92256.
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Kraft lignin has a high potential for use in more valuable applications than its current use as fuel in pulp mills and integrated pulp and paper mills. The possibility of using kraft lignin, a green material with a carbon content of more than 60 %, for the manufacturing of carbon fibres was investigated in this thesis. The strong and lightweight carbon fibre material has many potential application areas, e.g. in cars; the main obstacle limiting its demand is the high production cost, with the raw material (petroleum pitch and polyactrylonitrile) and fibre spinning constituting approximately 50 % of the cost. Industrial kraft lignins originating from both softwood (spruce/pine) and hardwood (birch/aspen) were isolated with the LignoBoost technique and then purified and characterized to determine the best suitable lignin for the production of carbon fibre. Using ultrafiltration of the black liquor before isolation using the LignoBoost technique, a kraft lignin with satisfactory high purity was obtained. The fractionated kraft lignin can be used either as such or as a softening agent during melt spinning to obtain continuously spun kraft lignin fibres. The behaviour during thermal treatment was found to differ depending on the type of kraft lignin used. After oxidative stabilisation, the studied lignins became more stable, and thus, the final yield after carbonisation was increased by 10-20 % in comparison to stabilisation in absence of oxygen. The identified products indicate that the main reactions during oxidative stabilisation are radical, oxidation, condensation and rearrangement reactions. The structural differences between softwood and hardwood kraft lignins facilitated the stabilisation of the softwood lignin fibre as compared with the hardwood lignin fibres. Thermal stabilisation in an inert atmosphere using only heat was successfully achieved for the softwood kraft lignin fibres. Stabilisation and carbonisation was successfully performed in a one-step operation on softwood kraft lignin fibres. Thus, it seems possible that the separate stabilisation step can be omitted, which may reduce the processing costs of softwood kraft lignin-based carbon fibres.Sulfatlignin har hög potential för att kunna användas i mer värdefulla applikationer jämfört med idag då det främst används som bränsle i massabruk och integrerade massa/pappersbruk. I egenskap av ett grönt material med en kolhalt på mer än 60 %, har möjligheterna att använda kraftlignin vid kolfibertillverkning undersöks i den här avhandlingen. Kolfiber är lätt och starkt med många olika potentiella användningsområden. Det som idag huvudsakligen begränsar efterfrågan är den höga produktionskostnaden, där råmaterialet (petroleum pitch och polyakrylonitril) och fiberspinningen står för ca 50 % av kostnaden. Industriella sulfatligniner från både barrved (gran/tall) och lövved (björk/asp) har framställts enligt LignoBoost-processen och har därefter renats och karaktäriserats med syfte att hitta det mest lämpliga råmaterialet för tillverkning av kolfiber. Genom att använda ultrafiltrering av svartlut innan isolering med LignoBoost-tekniken, kan man få ett kraftlignin som är tillräckligt rent. Det fraktionerade kraftligninet kan användas antingen rent eller som mjukgörare under smältspinning, för att få fram kontinuerligt spunna sulfatligninfibrer. Sulfatligniner från olika vedslag beter sig olika under termisk behandling. Efter oxidativ stabilisering blir ligninerna mer stabila jämfört med stabilisering i frånvaro av syre, vilket medför ett högre utbyte med 10-20 % av den slutgiltiga kolfibern efter karbonisering. De viktigaste reaktionerna som sker under oxidativ stabilisering av fibrer från sulfatlignin är radikal-, oxiderings- och omlagringsreaktioner. De strukturella skillnaderna mellan sulfatlignin från barrved och lövved gör det möjligt att stabilisera barrvedslignin mycket fortare. Termisk stabilisering i inert atmosfär med endast värme har lyckats med sulfatligninfibrer från barrved. Vidare har även stabilisering och karbonisering i ett enda steg lyckats med sulfatligninfibrer från barrved. Detta kan göra det möjligt att utesluta stabiliseringssteget, vilket förhoppningsvis kan reducera processkostnaderna för kolfiber från barrvedssulfatlignin.
QC 20120330
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Giummarella, Nicola. "Towards Liquid Fuels from Lignin." Thesis, KTH, Skolan för kemivetenskap (CHE), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-159172.
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The solubility of Lignoboost lignin was compared with softwood lignin precipitated from filtered black liquor and explained by Hilebrand as well as Hansen solubility parameters theory. The ability to dissolve efficiently lignin rises as the hydrogen bonding capacities together with the polarity of the solvents increases; similarly, their solubility parameter, according to Hildebrand, lay within the range between twelve and fourteen. Lower molecular weight lignin obtained by ultrafiltration is definitely more soluble than lignin obtained by Lignoboost process, especially at higher concentration. In addition, viscosity measurements show that solutions obtained from low molecular weight lignin are always less viscous than Lignoboost solutions. The gap in viscosity, between two lignins, becomes even higher at high concentration. The relationship between molecular weight of lignin and viscosity has been demonstrated by SEC analysis and application of Mark–Houwink–Sakurada equation. By ash content evaluation it has been possible to find out the most efficient conditions to lower salts formation when lignin is burnt. Several washes carried on with cold and acidic water have decreased the amount of ash to a value lower than 0,5% of dry weight. The effect of methanol fractionation on the molecular weight and its distribution of Lignoboost lignin has been investigated showing phase separation. The heavy and high lignin content fraction shows a pseudoplastic behaviour; however, its viscosity at low shear rate is too high to be interesting in a fuel production context and because the high volatility of methanol.
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Ayixiamuguli, Nueraimaiti. "Lignin degradation using lignolytic enzymes." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/35262/.
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Lignin is the only plant biomass that contains aromatic groups in its structure and can provide a wide range of low molecular weight aromatic chemicals if its depolymerisation can be achieved successfully. Currently, lignin is mainly produced as a waste by-product by the paper and pulp industry and biorefineries. Therefore, the transformation of the phenolic-rich lignin into value added aromatic platform chemicals can be regarded of primary concern to improve the economic profitability of biorefining. Moreover, being a renewable resource, the consumption of fossil fuels will be reduced if lignin can be utilised efficiently. Between chemical degradation and enzymatic degradation, the latter could be a more sustainable method to break down lignin due to its enhanced substrate specificity and ability to preserve the aromatic ring structure compared with chemical processing. Therefore, laccase from Trametes versicolor (LTV), lignin peroxidase (LiP) and manganese peroxidase (MnP) were studied to determine the scope to depolymerise both water-soluble and insoluble lignins nder mild reaction conditions. The enzymatic activity and stability of all three enzymes was investigated and optimum assay conditions were achieved. LTV was found to be the most stable enzyme as it maintained 55 % of its activity at least for the first 6 h at 30 °C whereas LiP was deactivated after 2 h at 25 °C, and MnP was deactivated after 1 h at 28 °C. However, LTV stability decreased at higher temperatures during the oxidation of 2,2’-azino-bis (3- ethylbenthiazoline-6-sulphonic acid (ABTS)). One of the non-phenolic lignin model compounds, veratryl alcohol, was oxidised by LTV in the presence of ABTS, thus confirming the published data. The enzymatic degradation of Organosolv lignin (OSL) by LTV resulted in the formation of 2,6-dimethoxy-1,4-benzoquinone (DBQ). The OSL degradation by LTV was not improved by ethanol addition as a co-solvent although ethanol could stabilise LTV at 40 % (v/v). LTV catalysed the degradation of Kraft lignin although it indicated little effect on lignosulphonates. Lastly, the effect of varying the concentrations of 92 ionic liquids (ILs) and their equivalent metal salts on LTV activity was investigated to find a suitable co-solvent to improve the poor mass transfer in OSL degradation. The study showed that 62 ILs were laccase compatible at an IL concentration of 6 % (w/v) and more than 50 % laccase activity was retained in 18 ionic liquids up to 10 % (w/v), and 80 % (v/v) of dioctyl sulfosuccinate quaternary ammonium salt, [N4,4,4,4][AOT]. However, there was a progressive loss of activity when the concentrations of the ILs increased. Further study on the enzymatic degradation of ILs-pre-treated OSL is currently ongoing in our research group so that the decomposition of water-insoluble lignin will be understood more comprehensively.
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Gilardi, Gianfranco. "Spectroscopic studies of lignin biodegradation." Thesis, Imperial College London, 1991. http://hdl.handle.net/10044/1/46785.
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Destiné, Jean-Nicolas. "Photodegradation of milled wood lignin." Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=69666.
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The photodegradation of lignin has been investigated using milled wood lignin (MWL) as a model. Solutions of MWL were exposed to ultraviolet (UV) light under aerobic and anaerobic conditions. Changes in the molecular weight distribution (MWD) of the lignin were assessed by gel permeation chromatography (GPC). To elucidate the chemical changes induced in the lignin by irradiation, infrared (IR) and UV spectra of the irradiated solutions were also studied. Irradiation under nitrogen causes the formation of both high molecular weight (MW) condensation products and low MW fragments; whereas, irradiation under oxygen yields only low MW fragments, similar to those found under nitrogen. Since the formation of condensation products can be attributed to free radical coupling, it follows that oxygen is probably reacting with free radicals to form peroxyl free radicals thereby avoiding condensation to higher MW products. Finally, the chemical basis of the photoinduced changes in the MWD of the lignin are discussed.
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Wells, Tyrone. "Lignin for bioenergy & biomaterials." Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/53575.
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Sustainable waste treatment and lignin development strategies targeted for biorefineries will benefit industry, consumers, and the environment. This dissertation demonstrates the feasibility of a novel biochemical pathway capable of converting sugars and lignin sourced from biorefinery waste streams into microbial oils suitable for biodiesel, cosmetic, and biopharmaceutical applications. This biochemical pathway also presents interesting avenues for the commercial production of higher-value intermediate metabolites such as catechol, protocatechuate, pyruvate, and succinate. Alternatively, this dissertation also demonstrates a unique polymerization strategy for lignin that can be adopted towards the production of green polymeric biomaterials. Overall, these strategies jointly present intriguing routes for lignin valorization.
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Choudhury, Hasneen. "Photoyellowing of lignin containing materials." Thesis, University of Kent, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.282456.
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Pedlar, Louise. "The microbial degradation of lignin." Thesis, University of York, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.333707.
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Ji, Xiaoyue. "Photochemical transformations of lignin models." Thesis, Queen's University Belfast, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.679240.
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The main aim of this project was to investigate the photochemical degradation pathways of lignin models using singlet oxygen and other photo-induced reactive species, in order to understand the photochemical transformations of the lignin polymer and other lignin-like polymers. The sensitized photolytic oxidation of lignin models containing the 13-0-4' lignin substructures using visible light, Rose Bengal and oxygen was studied in an attempt to understand and develop photocatalytic oxidation as a method for the conversion of lignin into added-value chemicals, Initial studies using a simple model dimer and attempting to replicate a published method[1] resulted in significant differences in the products when compared with the previous literature studies. A time study was carried out and a possible mechanism of a photo catalysed dimerization has been proposed. The observed radical coupling reaction has been shown to precede the eventual cleavage of a key benzylic ether bond in the tetramer and the formation of a quinone product and guaiacol by-product. Similar radical couplings were also observed for 13-5' dimer and trimer lignin models, Identification of the coupling products was obtained by spectroscopic characterization and corroborated by independent synthesis. Batch and flow reactors were tested and compared for the photolysis reactions. The flow reactor was proved to be more efficient than the batch reactor in terms of time-space conversion and yield. It was also shown that the flow reaction is a good method for the study of mechanism and optimization of the conditions required for the process, The dimerization process was then used for the preparation of three novel unsymmetrical coupling products. Successful cross-coupling of lignin models in this way provides a flexible new synthetic strategy for the preparation of more complex lignin models which is competitive with previous synthetic routes.
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de, Albuquerque Fragoso Danielle Munick. "Lignin conversion to fine chemicals." Thesis, University of Glasgow, 2018. http://theses.gla.ac.uk/30847/.
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The large availability of Kraft lignin as an industrial by-product and its polyaromatic characteristic, is ideal to consider the potential for recycling it into fine chemicals. To depolymerise lignin, solvolysis and hydrogenolysis experiments were performed. This research considered whether the low yields of products (fine chemicals) were related to the low content of β-O-4 bonds or if it was also associated to the dissolution of lignin in the solvent solution employed in the reactions. The type of solvents chosen to check the dissolution effect were those with low cost and were more sustainable than traditional solvents. Water, ethanol, isopropanol (IPA) and acetone were used. The water mixtures were applied in the tests in various proportions (25:75, 50:50, 75:25 solvent/water v:v). Due to their ability to break C-C and C-O bonds in lignin model compounds [1][2], the efficiency of platinum and rhodium in these reactions supported on alumina was also studied. It was found that the non-catalysed (solvolysis) and catalysed reactions showed different selectivities but similar overall yields ~ 10 % wt of monomeric phenols. The difficulty in increasing yields was mainly associated with the highly condensed character of Kraft lignin and re-polymerisation issues. To achieve an understanding of Kraft lignin depolymerisation, isotopic labelling reactions were completed in the presence of deuterated solvents as well as deuterium gas. This gave information on how Kraft lignin depolymerises, the influence of solvent to products formation and the involvement of hydrogen in the rate determining steps in the reactions. These results have led to an initial mechanistic understanding on how this complex molecule may yield alky-phenolic compounds. It was revealed that the solvent was directly involved in the products’ formation and that they were not generated by simple thermolysis. In addition, the presence of catalysts and hydrogen influenced product formation. The compounds showed different kinetic isotopic values, suggesting that each of these molecules came from individual mechanisms, highlighting the complexity of their formation. This was a relevant study as most of lignin depolymerisation mechanistic insights are based on model compounds and not on lignin itself. It was of interest to this project to explore not only different catalysts and their relationship to lignin depolymerisation, but also different lignin types. A simple pre-treatment for lignin extraction using sawdust (from oak and birch wood) in a Parr autoclave reactor in the presence of hydrogen, solvent and high temperature was developed. The lignins obtained after the pre-treatment were named parr-lignin and successfully resulted in polyaromatic molecules with less condensed character compared to lignins from Soda or Kraft pulping. Reactions were carried out with these lignins and a sugar-cane lignin. 4 5 Different catalytic systems with these lignins were investigated and how depolymerisation was affected by the metal and support used. The catalysts involved in the reactions included platinum, rhodium, nickel and iron. Various supports such as alumina, zirconia and carbon were tested along with the metals described. It was found that the supports were not inert in these experiments presenting catalytic activity. Materials with low surface area (zirconium catalysts) gave a poor performance compared to the others. In addition, nickel, a non-noble metal, showed as good a catalytic effect in the depolymerisation of these lignins as Pt and Rh. The components in the system influenced the reactions to different extents, especially product distribution. The catalysts had different selectivities and the solvents were not only dissolving lignin but also influencing the results. GPC analysis was performed to give an overview of the condensed level of these lignins and degrees of depolymerisation compared to the original material. GC-MS enabled the identification and quantification of 18 monomeric compounds. The post reaction characterisation of selected alumina catalysts (Pt/Al2O3, Ni/Al2O3 and Al2O3) was performed using XRD, BET, CHN, TPO and Raman Analysis to study the nature of the carbonaceous layer deposited on these materials. The work showed that after reaction the catalysts turned black in colour and the carbon laydown consisted of not only one simple type of carbon, and included graphitic species. The amount of carbon deposited depended on the type of lignin. Oak and birch parr-lignins had the highest and lowest amount of carbon over the catalysts respectively. No obvious trend relating to the type of catalyst, lignin and solvent used to the carbon nature was identified. This work showed that lignins with less condensed nature were less susceptible to solvolysis and more to hydrogenolysis. For example, sugar-cane lignin gave 3.9% of phenolic compounds in the solvolysis while reaction with Rh/Al2O3 gave 12.9% of products. This indicated that more selective cleavage of bonds were promoted by heterogenous catalysts. The results suggested that some compounds were mainly generated via dealkylation and hydrodeoxygenation, allowing a future possibility to generate target molecules. These results were mainly due to the presence of more labile bonds, vulnerable to hydrogenolysis. Highlighting that prior to depolymerisation, the pre-treatment used to extract lignin must be appropriate to avoid depletion of the alkyl-aryl ether bonds (β-O-4 bonds, especially) relevant for fine chemicals generation.
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Honkanen, M. (Markus). "Lignin depolymerization:significance of formic acid." Bachelor's thesis, University of Oulu, 2016. http://urn.fi/URN:NBN:fi:oulu-201604011373.
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Tämän työn tarkoituksena oli tutkia muurahaishapon toimivuutta vedynluovuttajana ligniinin depolymerisoinnissa ilman erillisen katalyytin käyttöä. Korkeissa lämpötiloissa ligniinin tiedetään kondensoituvan korkeasti polymerisoituneeksi hiileksi, mutta vedyn avulla tätä reaktiota voidaan ehkäistä. Muurahaishappo tunnetusti vapauttaa vetyä hajoamistuotteenaan. Työn toisena tavoitteena oli tuottaa teollisuuden sovelluksille käyttökelpoisia tuloksia. Tästä johtuen reaktiolämpötilat (250 °C ja 300 °C) ja liuoksen happamuus (8,82 m-% ja 17,64 m-%) pidettiin suhteellisen matalina. Tutkimus suoritettiin kahdessa osassa, joista ensimmäisessä keskityttiin löytämään reaktio-olosuhteet, joissa ligniiniä saataisiin depolymerisoitua mahdollisimman tehokkaasti. Reaktioissa syntyneet kaasumaiset ja nestemäiset reaktiotuotteet analysoitiin kaasukromatografilla. Reaktiossa käytettyä lämpötilaa sekä liuoksen happamuutta muunneltiin eri kokeiden välillä, jotta voitiin arvioida näiden tekijöiden vaikutusta reaktiotuotteiden koostumukseen. Tavoitteena oli tuottaa mahdollisimman paljon kaasua annettujen määreiden rajoissa, sillä teoreettisesti suurempi kaasuntuotto muurahaishapon hajotessa viittaa suurempaan vedyn määrään tuotteissa. Vety puolestaan on tärkeässä roolissa ligniinin polymerisaatiota ajatellen. Tutkimuksen toisessa vaiheessa ligniiniä lisättiin liuokseen olosuhteissa, jotka olivat ensimmäisen vaiheen tulosten mukaisesti parhaat ligniinin depolymerisoitumiseen. Kaikkien kokeiden aikana syntyneiden kaasu- ja nesteseoksien koostumukset analysoitiin kaasukromatografilla. Työn tuloksena saatiin jatkotutkimukseen hyödyllistä dataa matalan lämpötilan ja laimean hapon reaktiotoiminnoista ligniinille. Toistaiseksi juuri kyseisiä laimeita olosuhteita on tutkittu suhteellisen vähän. Vastoin aiempaa tietämystä, myös laimealla happoliuoksella kyettiin tuottamaan suhteellisen suuria määriä kaasua, mikä viittaa myös merkittävään vedyn määrään. Myös lämpötilan havaittiin vaikuttavan reaktioihin enemmän kuin alkuun oletettiin: korkeassa lämpötilassa suoritetut kokeet nostattivat reaktorin paineen huomattavasti korkeammaksi kuin matalan lämpötilan kokeet, jolloin myös kaasua syntyi enemmän. Kaasun CO/CO₂-suhde käyttäytyi painetta epäjohdonmukaisemmin, sillä sen arvo vaihteli riippumatta reaktio-olosuhteista. Yleisesti ottaen tulokset viittasivat vedyn määrän kasvamiseen lämpötilan noustessa. Molemmissa ligniinikokeissa syntyi sama määrä tuhkaa (noin 2 g). Tuhkan korkean koheesion vuoksi kunnollisen näytteen kerääminen osoittautui hyvin vaikeaksi, eikä sen tarkkaa massaa voitu siten mitata. Muurahaishappo osoittautui testien perusteella lupaavaksi vedynluovuttajaksi ligniinin depolymerisointiin. Ligniinitestien aikana onnistuttiin tuottamaan selkeästi suurempi hiilidioksidimäärä kuin pelkillä ensimmäisten testien muurahaishapon hajoamisreaktioilla. Tämä viittaisi ligniinin osittaiseen dekarboksylaatioon reaktioiden aikana. Jatkotutkimuksen kohteina voisi olla ligniinin depolymerisoinnin tarkastelu pidemmillä reaktioajoilla, eri vedynluovuttajien käyttö tai lisätutkimus laimean happoliuoksen riittävyydestä ligniinin rakenteen pilkkomiseenThe basis for this thesis was to explore how formic acid performs as a hydrogen donor in lignin depolymerization, when no additional catalyst is used. It is known that at high temperatures, lignin tends to recondense into highly polymerized fractions (char), and active hydrogen can cap these reactions to hinder char formation. Formic acid is known to release active hydrogen during its decomposition. Another goal was to make the results usable for the industrial applications. To succeed in this, only relatively low temperatures (250 °C and 300 °C) and acid content (8.82 wt % and 17.64 wt %) were used. The research was conducted in two stages, the first of which concentrated on finding the optimal reaction conditions for depolymerizing lignin into smaller fractions. The gas and liquid produced by the reactions were analysed by gas chromatography. The reaction temperature and acid content were changed to see how it affected the composition of the gas and liquid products. The goal was to achieve the greatest possible amount of gas within the defined parameters, because in principle more gas produced in the decomposition of formic acid suggests more potential hydrogen present in the product. The hydrogen in turn is essential for lignin depolymerization. In the second stage lignin was added to the reaction mixture at the conditions determined during the first stage. The products were analysed by gas chromatography. The research resulted in some useful data about the reactions occurring at low temperatures and acid contents. These conditions have remained relatively scarcely researched. Contrary to earlier knowledge, significant amounts of carbon dioxide could be produced even by using low acid content, which suggests that also notable amount of hydrogen was present. The temperature was also observed to affect the results more than was initially thought: the runs done at higher temperature saw an exponential increase in pressure and a greater gas yield than the ones done at low temperature. However, the CO/CO₂-ratio did not seem to be consistent, as it changed regardless of the conditions. These indicators suggested that more hydrogen was released by the reactions at higher temperature. Both depolymerisation experiments yielded about the same amount of char (ca. 2 g). However, due to the difficulty of char recovery given its high cohesion, the weight could not be accurately measured. Formic acid proved to be a promising hydrogen donor. During the lignin solvolysis experiments, a significantly larger amount of carbon dioxide was released than during the formic acid decomposition experiments. This suggests that lignin was partially decarboxylated during the reactions. Additional research should be conducted by using longer reaction times, having a different hydrogen donor or looking into the sufficiency of mild acid solution to depolymerize lignin
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Oliveira, Willer de. "Star-like macromers from lignin." Thesis, Virginia Tech, 1987. http://hdl.handle.net/10919/43255.
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Star-like macromers were prepared from hydroxypropyl lignin by reaction with propylene oxide. The average number of arms per macromer was controlled by partial capping with diethylsulfate, and the average arm length by the degree of chain extension with propylene oxide.
Six methods of analysis were applied for characterizing of the star-like macromers: total hydroxyl (by titration), vapor pressure osmometry, hydriotic acid/gas chromatography, ultraviolet spectroscopy, proton-nuclear magnetic resonance spectroscopy and thermal analysis.
Number average molecular weights were measured by vapor pressure osmometry. Total hydroxyl content was determined after acetylation by potentiometric titration. Based on HPL molecular weight and hydroxyl content it was estimated that the average HPL molecule generates a star-like structure ("macromer”) with an average of 6 arms.
Hydriodic acid/gas chromatography proved to be the most appropriate method for the quantitative determination of the degree of capping. Based on this technique it was possible to classify star-like macromers with between two and six radiating arms per average molecule. The same method could also be applied for the determination of arm length. Two different propoxylation reaction conditions produced macromers with an average of 2.5 and 3.5 propylene oxide units per arm.
Ultraviolet spectroscopy was the simplest and most rapid method of analysis investigated. The decrease in copolymer absorptivity coefficient was found to be related to an increase in non-UV absorbing mass after capping and/or chain extension.
Results indicated that H-NMR spectroscopy is an adequate method of analysis for star-like macromers. Macromer arm length was calculated from the ratio of signals representing the methyl group of acetyl (i.e. hydroxyl) and propoxyl functionality. Two levels of propoxylation produced star-like macromers with 2.2 - 2.5 and 3.9 - 4.0 propylene oxide units per arm.
Thermal analysis by DMTA of lignin derivative-containing blends with ethylene-vinyl acetate copolymer indicated that the glass transition behavior of the star-like macromers follows the Gordon-Taylor relationship for copolymers. Although variable, the results revealed a consistent decrease in Tg as a consequence of an increase of propylene oxide chain length.Master of Science
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Linder, Kristoffer. "Optical Characterization of Lignin Nanoparticles." Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-79864.
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Lignin is one of the main components of wood and plants that acts as a kind of glue providing mechanical strength. It is a main polymer component composed from three phenolic structures, i.e. p-hydroxyphenyl (H), guaiacyl (G) and syringyl (S) units. It currently draws a lot of attention due to its eco-friendly. Recently, it has been shown that it is possible to produce lignin nanoparticles, small spherical particle that are composed out of lignin, that could possibly be used to replace the hazardous silver nanoparticles that are today used frequently in numerous applications. Lignin nanoparticles could potenitally also be used as functional coatings, as well as biologically degradable adhesives and float switches. Five samples, of nanoparticles, were investigated in this study. The first contained pure lignin nanoparticles, the second pure silver nanoparticles, and the three remaining samples contained lignin-coated silver nanoparticles, extracted from acetone, tetrahydrofuran (THF), and dimetylformamid (DMF) solvents. All samples were characterized using spectroscopic methods, e.g. infrared- and dark-field imaging, as well as UV-Vis-, fluorescence-, and Raman spectroscopy. In this thesis it was shown that lignin-coated silver nanoparticles exhibit surface plasmon resonance which induces a heat effect upon infrared irradiation. To identify the phenolic structures of lignin, UV-Vis spectroscopy was used. It was found that the spectra of the samples exhibited several intense bands. The objective of the UV-Vis spectroscopy was to examine the absorbance characteristics of the lignin-coated silver nanoparticles. Possible surface plasmon resonance wavelengths were determined, and two of the phenolic structures were identified. In this study, Raman spectroscopy was used to define characteristic bands of the samples. This was done to investigate if the lignin nanoparticles have the same characteristics as bulk lignin. Raman spectroscopy provide structural information of lignin. Furthermore, p-hydroxyphenyl, guaiacyl and syringyl structures could be identified with an excitation wavelength of 532nm. A comparison of the spectra of the lignin-containing samples indicated the the Raman features of the specimens were similar meanwhile almost no signs of silver were present, which might show that the particles were fully covered with lignin. Main lignin bands were identified and assigned. The fluorescent properties of the nanoparticles were investigated by obtaining emission spectra for blue-, green- and UV light excitation. The spectra were deconvoluted into their Gaussian components. Emission spectra were obtained for blue-, green- and UV light excitation. It was found that the fluorescence, after UV light exposure, increased with time of exposure. Dark-field microscopy was used to generate light scattering images of the particles. As a result, optical images with different colors (white, yellow, blue and red) could be revealed. The color information, that is related to the size of the particles, was used to estimate ratios of the different particle sizes. The lignin-coated silver nanoparticles, extracted from acetone, exhibited a strong surface plasmon resonance effect, which could be due to the absorbance at 463nm. The lignin-coated silver nanoparticles, extracted from DMF, exhibited a medium surface plasmon resonance effect, which could be due to the absorbance at 362nm. The lignin-coated silver nanoparticles, extracted from the THF solvent, exhibited a weak surface plasmon resonance effect, which could be due to the absorption at 379-380nm. The pure lignin- and silver nanoparticles merely showed bulk heating but no surface plasmon resonance effect could be detected.Lignin är en av huvudbeståndsdelarna av trä och plantor som fungerar likt ett lim som ger mekanisk styrka. Lignin är en biopolymer, som består av tre fenylgrupper: p-hydroxifenyl (H), guaiacyl (G) och syringyl (S). På senaste tid har det visat sig att det är möjligt att tillverka lignin nanopartiklar, det är små sfäriska partiklar som är helt gjorda av lignin, som skulle kunna ersätta de miljöfarliga silver nanopartiklarna som i nuläget används i många olika tillämpningar. Lignin nanopartiklar kan potentiellt också användas som funktionella ytbeläggningar, såväl som biologiskt nedbrytbara lim och flottörer. Fem prover, av nanopartiklar, undersöktes i denna studie. Det första provet innehöll lignin nanopartiklar, det andra silver nanopartiklarna, och de tre återstående proverna innehöll ligninbelagda silver nanopartiklar, extraherade från aceton, tetrahydrofuran (THF) och dimetylformamid (DMF). Alla prover karakteriserades med hjälp av spektroskopiska metoder: infraröd- och mörkfältavbildning, liksom UV-Vis-, fluorescens- och Ramanspektroskopi. I denna avhandling visades att ligninbelagda silver nanopartiklar uppvisar ytplasmonsresonans, vilket inducerar en värmeeffekt vid infraröd bestrålning. För att identifiera ligninets fenylgrupper användes UV-Vis-spektroskopi. Det visade sig att spektra från proverna uppvisade flera intensiva band. Målet med UV-Vis-spektroskopin var att undersöka absorptionsegenskaperna hos de ligninbelagda silvernanopartiklarna. Möjliga ytplasmonresonansvåglängder bestämdes och två av fenylgrupperna identifierades. I denna studie användes Ramansspektroskopi för att definiera karakteristiska band för proverna. Detta gjordes för att undersöka om lignin nanopartiklarna har samma egenskaper som bulk lignin. Ramanspektroskopi ger information om ligninets struktur. Vidare identigierades p-hydroxifenyl-, guaiacyl- och syringylstrukturerna med en excitationsvåglängd på 532nm. En jämförelse av spektra för de lignininnehållande proverna indikerade att provernas Raman-kännetecken var liknande medan nästan inga tecken på silver fanns, vilket kan visa att partiklarna var täckta med lignin. Huvudsakliga ligninband kunde identifieras. Fluorescensegenskaperna, hos nanopartiklarna, undersöktes genom de erhållna emissionspektra efter exponering av blå-, grön- och UV-ljus. De erhållna spektra dekonvoluterades till dess gaussiska komponenter. Det visade sig att fluorescensen, efter exponering av UV-ljus, ökade med exponeringstiden. Mörkfältmikroskopi användes för att generera bilder på partiklarna. De resulterade i bilder med olika färger (vitt, gult, blått och rött) som motsvarade olika partikelstorlekar och geometrier. På så sätt kunde färhållandena mellan de olika partikelstorlekarna uppskattas. De ligninbelagda silver-nanopartiklarna, extraherade från aceton-lösningen, uppvisade en stark ytplasmonresonanseffekt, vilket kan bero på absorptionen (från absorptionsspektrat) vid 463nm. De ligninbelagda silver-nanopartiklarna, extraherade från DMF-lösningen, uppvisade en medelstark ytplasmonresonanseffekt, vilket kan bero på absorptionen vid 362nm. De ligninbelagda silver-nanopartiklarna, extraherade från THF-lösningen, uppvisade en svag ytplasmonresonanseffekt, vilket kan bero på absorptionen vid 379-380nm. De rena lignin- och silver-nanopartiklarna uppvisade endast uppvärmning men ingen ytplasmonresonanseffekt.
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Mehta, Akul. "Synthetic, Sulfated, Lignin-Based Anticoagulants." VCU Scholars Compass, 2014. http://scholarscompass.vcu.edu/etd/598.
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Chemoenzymatically synthesized low molecular weight lignin polymers have been previously found to be potent inhibitors of a number of serine proteases via allosteric mechanisms targeting heparin binding sites. Herein, we describe the creation of synthetic sulfated β-O4 lignin (SbO4L) polymer, which is more homogenous compared to previous lignins with respect to its inter-monomeric linkage. SbO4L is a selective inhibitor of thrombin and plasmin. SbO4L was found to act via a unique mechanism targeting thrombin exosite 2 in a manner similar to platelet glycoprotein Ibα (GPIbα). Advanced hemostasis and thrombosis assays demonstrated that SbO4L acts via a dual mechanism: as an anticoagulant, by allosteric inhibition of thrombin catalysis; and as an antiplatelet agent, by competing with platelet GPIbα. These mechanisms are comparable in potency to low molecular weight heparins currently used in the market, indicating that targeting exosite 2 may yield clinically useful drugs in the future. Since the β-O4 type lignin was found to be selective for thrombin and plasmin, we hypothesized that other scaffolds from lignins could be potent inhibitors of other serine proteases. In particular, we screened a library of synthetic sulfated small molecules against factor XIa – an emerging target for prophylactic anticoagulation. Our search identified a sulfated benzofuran trimer (a mimic of β-5 type linkage found in lignins) as a potent inhibitor of factor XIa. Surprisingly, this inhibitor did not compete with heparin. A plausible binding site in the A3 domain of factor XIa was proposed by using molecular modeling techniques. The binding pose demonstrated good correlation with the structure activity data from in vitro studies. Further confirmation that the apple domains were required was proved by testing the trimer against recombinant catalytic domain. A 40-fold decrease in activity was observed. A temperature-dependant perrin plot demonstrated that factor XIa undergoes a large conformational change in the presence of the trimer, which is possibly converting the enzyme back into the zymogen-like shape. In general, the synthetic sulfated lignins can act as a useful foundation to develop anticoagulant, antiplatelet, and anti-inflammatory molecules in the future.
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Kozik, Patrycja. "Prépolymères à base de lignines pour la rigidification de formulations d'élastomères." Thesis, Reims, 2016. http://www.theses.fr/2016REIMS023.
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Le cadre industriel de ce projet est de trouver une alternative à la résine phénol-formaldéhyde (RFP) et à son durcisseur, utilisée actuellement en pneumatique pour améliorer les performances aussi bien des compositions de caoutchouc que celles des produits semi-finis. Un des aspects essentiels de la pneumatique est d’augmenter la rigidité à faible déformation des pneus sans augmenter l'hystérésis des élastomères durcis chargés de noir de carbone. Ainsi, l'objectif de ce travail de thèse est de proposer un système thermodurcissable alternatif aux résines RFP actuelles. Ce nouveau système doit être riche en carbone renouvelable et doit être chimiquement modifié au moyen de procédés écologiques. La lignine a été choisie comme source de carbone renouvelable. Une étude préliminaire a souligné les potentialités d'une classe de lignines époxy pour l'application visée. Notre approche consiste en la conception de lignines modifiées par des époxy par une méthode originale évitant l'utilisation de l'épichlorhydrine suivie de son durcissement par des agents de réticulation appropriés. Des tests préliminaires avec un composé modèle de lignine ont donné la gamme des composés époxy et les conditions à tester pour la réaction avec la lignine. Les expériences avec la lignine ont alors confirmé le potentiel de l’ester diglycidylique de l’acide 4, 5-époxytetrahydrophthalique, un composé époxy contenant à la fois un groupement cycloaliphatique et deux types de groupements époxy glycidyliques, comme alternative à l'épichlorohydrine pour la préparation de lignines modifiées. Dans les conditions que nous avons définies, la réaction donne des prépolymères de type lignine-époxy sous forme de poudre avec un niveau d’époxydation de 1,2 mol/kg déterminé par spectroscopie FTIR. La série de tests effectuée sur des mélanges de caoutchouc a montré que la nouvelle lignine époxy associée à la p-xylylènediamine peut être mélangée avec succès avec le caoutchouc naturel et peut atteindre les propriétés de notre mix de référenceThe industrial framework of this project is the substitution of phenol formaldehyde resin (RFP) and its methyl donor hardener currently used for improving the performances of rubber compositions of tires or semi-finished products for tires. A critical aspect is the need for an increase of rigidity at low deformation without enhancement of the hysteresis of the cured elastomers filled with carbon black. The specific aim of this PhD work was to propose an alternative thermosetting system to the current RFP resins. This new system should be rich in renewable carbon and chemically modified by environmentally friendly processes. Lignin was chosen as the source of the renewable carbon. A preliminary study emphasized the potentialities of a class of epoxy-modified lignins for the targeted application. The main approach was the design of epoxy modified lignin to be obtained by an original method avoiding the use of epichlorohydrine and to be subsequently cured by appropriate cross-linkers. A preliminary screening with a lignin model compound gave the range of the epoxy compounds and the conditions to be tested for the reaction with lignin. Then various experiments with lignin confirmed the potential of 4, 5-epoxytetrahydrophthalic acid diglycidylester, an epoxy compound containing both one cycloaliphatic and two glycidyl type of epoxy groups, as an alternative for epichlorohydrine for the preparation of modified lignin. In the conditions we have defined, the reaction yielded epoxy lignin-based prepolymers as a powder with epoxy level as high as 1,2 mol/kg determined by FTIR spectroscopy. The series of evaluation campaigns in rubber blends showed that the new epoxy-modified lignin associated with p-xylylenediamine can be successfully mixed with natural rubber and enable to reach the properties of our reference mix
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Esakkimuthu, Esakkiammal Sudha. "Etude de nouvelles techniques de dérivation chimique de la lignine en vue de l'analyse par chromatographie d'exclusion stérique." Thesis, Université Grenoble Alpes, 2020. https://tel.archives-ouvertes.fr/tel-02612598.
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La lignine, deuxième biopolymère le plus abondant sur Terre, possède une structure aromatique tridimensionnelle hautement ramifiée, porteuse de différents groupements fonctionnels, principalement alcooliques et phénoliques. Le travail de recherche a porté sur les méthodes de dérivation chimique de la lignine permettant de quantifier les hydroxyles et de déterminer les distributions de masses molaires des lignines par chromatographie d’exclusion stérique et multi-détection. Cinq lignines techniques ont été étudiées : Protobind 1000, Organosolv (CIMV), lignine Kraft de pin, lignine Kraft d’Eucalyptus et lignine Indulin. L’acétylation, méthode classique de dérivation des hydroxyles, a été comparée aux nouvelles méthodes de fluoro-dérivation développées durant l’étude (fluorobenzylation et fluorobenzoylation). Les fonctions hydroxyle ont été quantifiées par titrages conductimétriques et potentiométriques, aminolyse-GC, spectrométries IR et UV- différentielle, et spectrométrie RMN (1H, 13C, 19F et 31P). La distribution des masses molaires des lignines dérivées a été déterminée en utilisant différentes colonnes et solvants (DMAc et THF). La méthode d’étalonnage standard, utilisant différents polymères standards de calibration, et la méthode dite “d’étalonnage universel”, utilisant la détection viscosimétrique couplée à la réfractométrie, ont été comparées. La fluoro-dérivation augmente la solubilité de la lignine dans le THF et améliore les résultats chromatographiques. L'étalonnage universel conduit à environ trois fois les valeurs de masses molaires calculées par étalonnage standardLignin is the second most abundant biopolymer on earth and it consists of highly-branched, three dimensional aromatic structures with variety of functional groups, mainly phenolic and alcoholic functions. This research work was focused on derivatization methods to quantify hydroxyl groups in lignins and to determine lignin molar mass distribution by size-exclusion chromatography coupled to multi-detectors. Five different technical lignins were studied: Protobind 1000, Organosolv (CIMV), Pine Kraft, Eucalyptus Kraft and Indulin. Lignin samples were washed and derivatized by classical acetylation, which was compared to fluoro-derivatization using the new methods developed in this work, such as fluorobenzylation and fluorobenzoylation. Hydroxyl groups present in the lignin samples were quantified by potentiometric and conductometric titrations, GC-aminolysis, IR and differential UV spectroscopies and NMR spectroscopy (1H, 13C, 19F and 31P). Molar mass distributions of derivatized lignins were calculated using different columns and solvents (DMAc and THF). Conventional calibration, using different standard polymers as calibrants, was compared to the so-called “universal calibration method”, which uses viscometric and refractometric detectors. Fluoro-derivatization enhanced lignin solubility in THF and improved chromatographic results. Universal calibration led to about three times higher molar mass values than by conventional calibration
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Olarte, Mariefel Valenzuela. "Base-catalyzed depolymerization of lignin and hydrodeoxygenation of lignin model compounds for alternative fuel production." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/39613.
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This study considered the potential use of lignin as possible renewable fuel and chemical feedstock source. Among the various polymers present in lignocellulosic biomass, the polyaromatic lignin is the one component that is most chemically similar to petroleum. However, it still contains a much larger amount of oxygen compared to crude oil. As such, two strategies were employed in this study: (1) studying the lignin depolymerization in the presence of high temperature and base catalysts; and, (2) employing hydrodeoxygenation as a means to decrease the O/C ratio in lignin-derived model compounds.
The base-catalyzed depolymerization (BCD) of organosolv lignin was done in a 500-mL Monel Parr reactor at temperatures ranging from 165°C to 350°C. Complete solubilization of lignin derivatives was possible in the presence of NaOH and KOH, except at 350°C. NMR experiments revealed formation of oxidized groups (carboxylic and hydroxyl groups) as well as alkyl groups. On the other hand, the use of NH4OH showed N incorporation. Identified and quantified DCM-soluble monomeric compounds were at most 6% of the starting material and are mainly phenolic. This study revealed the apparent susceptibility of syringyl units over guaiacyl units in BCD. This could in turn guide the choice of substrate on which base-catalyzed depolymerization could be applied.
Syringaldehyde was used as the starting material to study batch hydrodeoxygenation (HDO) using several non-cobalt/molybdenum based catalysts. A 50-ml Parr reactor was used, pressurized by 1000 psig of H2 and heated to 300°C. Nickel based catalysts (nickel phosphide, nickel oxide and nickel phosphate) as well as supported precious metals (Pt and Pd) were tested as HDO catalysts. Of the three O-containing functional groups of syringaldehyde, the aldehydic group was found to be the most susceptible. In the presence of the Al2O3-supported catalysts, the methyl groups liberated were found to be incorporated back into the aromatic ring, forming alkylated compounds.
In the last section of this dissertation, hydrothermally synthesized supported Ni on mesoporous silica (MCF) and acid catalysts (HY and H-Al-MCF) were used for probing the effect of bifunctional metal-acid catalysis on phenol hydrodeoxygenation/hydrogenation. Catalyst configurations were varied from the previously studied wet-impregnated Pt/HY catalyst. Based on a hypothesis that coking catalyzed by the acidic zeolite in the wet impregnated Pt/HY catalyst was the main cause of catalyst deactivation and decreased phenol conversion, separately synthesized metal and acid catalyst systems were tested. Complete phenol conversion was sustained for at least three times longer in a continuous flow reactor operated at 200°C and 0.79 MPa of flowing H2. The separation of the metal and acid sites generated a tunable system capable of producing cyclohexanol, cyclohexane or cyclohexene at very high selectivities, even achieving 99% selectivities for cyclohexane.
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Pattrick, Calum. "Lignin it, to win it : transformation, toxicity and transport in the microbial utilisation of lignin." Thesis, University of Sheffield, 2017. http://etheses.whiterose.ac.uk/19046/.
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Devadas, Suchitha. "Fabrication of Lignin-Based Nanofibers: Influence of Lignin Type, Blend Ratios, and Total Polymer Concentration." University of Dayton / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=dayton160831003121355.
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Sobczak, Jullyana Cristina Magalhães Silva Moura 1984. "Controle do teor de lignina em Eucalyptus, variação interespecifica e induzida por frio." [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/315661.
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Orientador: Paulo MazzaferaDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia
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Resumo: O controle de deposição de ligninas em diferentes espécies de Eucalyptus foi estudado utilizando baixa temperatura como modulador. Em baixas temperaturas, foi observada redução significativa dos crescimentos foliares de E. camaldulensis, E. grandis e E. pellita e isto pareceu ser um mecanismo adaptativo a este tipo de estresse. Em E. camaldulensis e E. pellita ocorreram reduções significativas dos crescimentos caulinares. Já em E. globulus, foi observado um aumento significativo destes crescimentos, demonstrando existir temperaturas preferenciais para cada espécie que podem estar relacionadas com a distribuição natural das mesmas, bem como com padrões de atividades enzimáticas, expressões gênicas e acúmulo diferencial de ligninas. Foi observada uma atividade diferencial de guaiacol peroxidase (GPX), siringaldazina peroxidase (SPX) e polifenoloxidases (PPO) nas espécies de Eucalyptus expostas às baixas temperaturas. Adicionalmente, foi observado também um padrão de expressão gênica diferenciado para as enzimas envolvidas na biossíntese dos precursores monolignóis das ligninas e variações na deposição de ligninas, indicando haver um efeito dos tratamentos de baixas temperaturas nestes processos. Em E. pellita, as maiores atividades de peroxidases e polifenoloxidases nas regiões apicais das plantas expostas aos tratamentos de baixa temperatura foram acompanhadas de um maior acúmulo de ligninas nessas regiões, bem como de uma redução do crescimento caulinar. Em E. grandis e em E. camaldulensis observou-se que as atividades de peroxidases e polifenoloxidases tendem a ser maiores em baixas temperaturas. Observou-se também uma maior expressão de importantes genes envolvidos na biossíntese dos monolignóis precursores das ligninas, mas isto não foi acompanhado de uma maior deposição de ligninas nestas plantas. Em E. grandis não ocorreram reduções dos crescimentos caulinares em baixas temperaturas, mas em E. camaldulensis as reduções observadas poderiam estar relacionadas como outros fatores, como uma maior degradação de AIA, promovida pelo aumento das atividades de peroxidases. Em E. globulus foram observadas reduções significativas das atividades enzimáticas analisadas, tanto nas amostras de ápices quanto em bases caulinares, expostos às baixas temperaturas. Esta menor atividade enzimática também foi acompanhada de uma menor expressão de genes envolvidos na biossíntese de ligninas. Observou-se uma redução da concentração de ligninas determinadas por ácido tioglicólico nas amostras de ápice e base das plantas expostas às baixas temperaturas e a quantidade de lignina insolúvel e solúvel, determinada pelo método Klason, aumentou nas amostras de ápices. Deste modo, em E. globulus, a maior tendência de redução de ligninas poderia estar associada com o maior crescimento desta espécie em baixas temperaturas. Ao utilizar um estresse como modulador da biossíntese de ligninas, alguns dos genes envolvidos puderam indicar possíveis pontos específicos do metabolismo de ligninas a serem alterados para se produzir plantas melhoradas com menor teor deste polímero
Abstract: The control of lignin deposition in different Eucalyptus species was studied using low temperature as a modulator. Under low temperatures, a significant reduction of leaf growth was observed in E. camaldulensis, E. grandis and E. pellita and this seemed to be an adaptive mechanism to this type of stress. Significant reductions of stem growth were observed for E. camaldulensis and E. pellita. In contrast, a significant increase of stem growth was found for E. globulus, indicating that the optimal growth temperatures for each species might reflect their natural distribution or patterns of enzymatic activities, patterns of gene expression and differential accumulation of lignins. Differential activities of guaiacol peroxidase (GPX), syringaldazine peroxidase (SPX) and polyphenol oxidases (PPO) were observed for the Eucalyptus species exposed to low temperatures. It was also observed that a pattern of differential gene expression exists for the enzymes involved in the biosynthesis of monolignol lignin precursors, as well as variations in lignin deposition, indicating an effect of the low temperature treatments in these processes. The increased peroxidase and polyphenol oxidase activities in the stem apical regions of E. pellita plants exposed to the low temperature treatments were accompanied by an increase in lignin accumulation in these regions. A reduction in stem growth was also found in this species. It was observed that the peroxidase and polyphenol oxidase activities tend to be greater under low temperatures for both E. grandis and E. camaldulensis. Additionally, a transcriptional increase of important genes involved in the biosynthesis of monolignol lignin precursors was found, although this was not accompanied by an increase in lignin deposition in these plants. A reduction in stem growth was not observed at low temperatures for E. grandis but in E. camaldulensis the observed reduction in growth could also be related to others factors, such as a greater degradation of AIA promoted by the increase in the activity of peroxidases. A significant reduction was observed for all of the enzymatic activities analyzed, in both shoot tips and shoot bases of E. globulus plants exposed to low temperature treatments. This lower enzymatic activity was also accompanied by a lower expression of genes involved in lignin biosynthesis. The amount of lignin determined by thioglycollic acid in the samples of shoot tips and shoot bases of the plants exposed to low temperatures was reduced and the amount of acid insoluble and soluble lignin, determined by the method of Klason, increased significantly in the shoot tips. Thus, the tendency of reducing lignin content under cold treatment observed for E. globulus could be associated with its increase in growth at low temperatures. By using a stress as a modulator of lignin biosynthesis, some of the genes involved may indicate possible specific points of lignin metabolism that could be changed when breeding plants for lower content of this polymer
Mestrado
Mestre em Biologia Vegetal
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Takahashi, Natália Gonçalves. "Caracterização molecular do fator de transcrição shine e seu potencial como regulador master na síntese de parede celular secundária em Sorghum bicolor L. /." Jaboticabal, 2017. http://hdl.handle.net/11449/150860.
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Orientador: Dilermando PerecinCoorientador: Michael dos Santos Brito
Coorientador: Silvana Aparecida Creste Dias de Souza
Banca: Elisson Antônio da Costa Romanel
Banca: Luciana Rossini Pinto
Resumo: A busca pela diversificação de fontes da matriz energética, priorizando fontes renováveis, acarreta no maior consumo de etanol de primeira geração, podendo este ser insuficiente em suprir a necessidade da frota brasileira. Dessa forma, o etanol de segunda geração (E2G) surge como uma alternativa para aumento da produção de combustíveis renováveis. Ele é produzido a partir da fermentação dos resíduos de glicose após a quebra da celulose presente na biomassa vegetal. Contudo, além da celulose, a biomassa vegetal é também composta pela lignina, composto considerado recalcitrante no processo de obtenção deste tipo de etanol. Para transpor este obstáculo, é necessário encontrar maneiras de diminuir a quantidade ou modificar a composição da lignina. Fatores de transcrição (FTs) são alvos altamente promissores para a modificação deste polímero, uma vez que estão envolvidos com a regulação de sua via de biossíntese, bem como, da formação de toda parede celular secundária (PCS). Plantas de arroz transformadas para a superexpressão de AtSHN2 de Arabdopsis, apresentaram uma diminuição na quantidade de lignina e mostraram uma modulação na via de celulose, enquanto que a superexpressão do outro gene SHN de Arabidopsis (AtSHN1) em Arabidopsis apresentou uma modificação na via de biossíntese de cera e cutina. Isto ressalta a necessidade de avaliar os FTs de maneira espécie-específica. Assim sendo, este trabalho vem com o objetivo de ajudar a elucidar os mecanismos de funcionamento do FT SHI... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The search for alternative sources of the energy, prioritizing renewable sources, increase the consumption of first generation ethanol, which could not be enough to supply the needs of the Brazilian flex fuel car fleet. In this scenario, second generation ethanol (E2G) appears as an alternative to increase production of renewable fuels. E2G it is produced from the fermentation of glucose residues after breaking the cellulose present in the plant biomass. However, adhered to the cellulose is lignin, a compound considered recalcitrant in the process of obtaining this type of ethanol. To overcome this obstacle, it is necessary to find ways to decrease the amount or modify the lignin composition. Transcription factors (TFs) are highly promising targets for the modification of this polymer, since they are involved in the regulation of its biosynthesis pathway, as well as the formation of the whole secondary cell wall (PCS). Rice plants transformed for the overexpression of AtSHN2 from Arabidopsis showed a decrease in the amount of lignin and a modulation of cellulose pathway whereas the overexpression of another gene of SHN (AtSHN1) in Arabidopsis showed a modification in the biosynthesis pathway of wax and cutin. This highlights the need to evaluate TFs in a species-specific manner. Basing on this, the present work has the objective of helping to elucidate the mode of action of TF SHINE (SHN), considered a potential regulator of PCS in grasses. Aiming to characterize SbSHN TF in ... (Complete abstract click electronic access below)
Mestre
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Velasquez, Alejandro Vargas. "Comparação dos métodos lignina detergente ácido (LDA), lignina permanganato de potássio (LPer), lignina Klason (LK) e lignina brometo de acetila (LBA) na determinação do teor de lignina em plantas forrageiras e correlação com digestibilidade in vitro da matéria seca (DIVMS)." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/10/10135/tde-10092014-113254/.
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O desempenho animal pode ser melhorado pelo incremento na digestibilidade dos alimentos. Um dos elementos neste processo é a acurada caracterização da composição química. Objetivando avaliar quatro métodos para determinar o teor de lignina, foram estudadas cinco gramíneas: Brachiaria brizantha cv. Marandú, Brachiaria brizantha cv. Xaraés (MG-5), Panicum maximum cv. Mombaça, Pennisetum purpureum cv. Cameroon e Pennisetum purpureum cv. Napier. As frações fibrosas da parede celular (PC), fibra em detergente neutro (FDN) e fibra em detergente ácido (FDA) aumentaram conforme as plantas amadureceram, refletindo as mudanças na composição dos componentes da parede celular (celulose, hemicelulose e lignina). Os valores de PC foram superiores aos da FDN indicando solubilização da pectina e outros oligossacarídeos da parede celular na solução de detergente neutro. O método LDA apresentou os menores teores de lignina, evidenciando a solubilização de parte da lignina na solução de detergente ácido. Os resultados de LPer foram maiores que os de LDA, que pode ser devido à oxidação da celulose e pectina pelo permanganato de potássio. Os teores de LK foram maiores que os de LDA possivelmente por contaminação protéica, mas, menores que os de LPer. Os teores de LBA foram maiores que os outros três métodos. A digestibilidade acompanhou, de forma inversa, o estádio de maturidade das plantas. A digestibilidade in vitro apresentou forte correlação negativa com os teores de lignina para todos os métodos, menos para LPer. Encontrou-se um valor de relação de 2,23, entre os métodos LDA e LBA, que, ao ser aplicado, nos teores de LDA, resultou em reta similar ao da LBA. Chama a atenção como este valor de 2,23 é muito próximo ao 2,4 utilizado nas equações B2 e C das frações de carboidratos do \"Cornell Net Carbohydrate & Protein System\" e nas equações do National Research Counsil de 1996, para corrigir o teor de lignina. O método LBA é um método fácil e conveniente para determinar a concentração de lignina em forrageiras e uma boa opção para uso rotineiro nas análises de laboratório.Animal performance can be improved by enhancing feed digestibility. One of the elements for this process is an accurate characterization of feedstuff chemical composition. With the objective of evaluating four methods used today for lignin determination, five grasses were used: Brachiaria brizantha cv. Marandú, Brachiaria brizantha cv. Xaraés (MG-5), Panicum maximum cv. Mombaça, Pennisetum purpureum cv. Cameroon e Pennisetum purpureum cv. Napier, All fibrous fractions, neutral detergent fiber (NDF), acid detergent fiber (ADF) and cell wall (CW), increased as the plants matured, reflecting the changes in the CW composition (cellulose, hemicellulose and lignin). The values obtained for CW were higher than those obtained for NDF, indicating solubilization of pectin and other cell wall oligosaccharides in the neutral detergent solution. The ADL method produced the lowest lignin values, reflecting lignin solubilization by the acid detergent solution. PerL results were higher than those of ADL, possibly due to hemicellulose and pectin oxidation by potassium permanganate. The values for KL were higher than those of ADL, possibly due to protein contamination, but were lower than PerL values. ABL values were the highest among all methods. Digestibility inversely followed plant maturity throughout the study. In vitro dry matter digestibility showed high negative correlation with lignin contents. A 2,23 ratio between ADL and ABL methods was found, which when applied to ADL values, resulted in a curve similar to ABL method curve. It is interesting to note that, this value of 2,23 is very close to the 2,4 used in carbohydrate fractions B2 and C of the \"Cornell Net Carbohydrate & Protein System\", for the correction of lignin content. The ABL method is easy and convenient for total lignin content determination in forages.
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Ahmad, Mark. "Development of novel assays for lignin breakdown and identification of a new bacterial lignin degrading enzyme." Thesis, University of Warwick, 2010. http://wrap.warwick.ac.uk/4477/.
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Two novel spectrophotometric assays have been developed for high throughput screening of microbial lignin degradation. The first assay involves fluorescently labelled lignin, which gives a time dependent increase in fluorescence with lignin degradation. The second involves nitrated lignin where an increase is seen at 430nm when lignin is broken down. These assays have allowed identification of a number of new strains of lignin degrading bacteria including R. jostii RHA1. They have also allowed the comparison of bacterial and fungal degraders and a study of lignin specificity. Bioinformatics has been used to identify two putative lignin degrading enzymes in R. jostii RHA1. Their role in lignin degradation was investigated by assaying of gene knockouts. This led to the detailed study of a new recombinant peroxidase, DypB, using lignin, lignocellulose and lignin dimer model substrates. This represents the first recombinant bacterial lignin degrading enzyme to be characterised. In addition methods for studying the products of lignin breakdown by HPLC, GC/MS and LC/MS have been developed. This has led to the identification of several low molecular weight aromatic products including ferulic acid. It has also been shown that the products released from lignin model compounds can be controlled by addition of the reductive enzyme diaphorase.
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Mottweiler, Jakob [Verfasser]. "Transition metal-catalyzed oxidative cleavage of lignin and lignin β-O-4 model compounds / Jakob Mottweiler." München : Verlag Dr. Hut, 2016. http://d-nb.info/1100968946/34.
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Chaudhary, R. "Employment of heterogeneous base catalysts in the depolymerization of lignin and upgradation of lignin model compounds." Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2017. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/4509.
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Eberhardt, Thomas Leonard. "Studies on lignin biosynthesis and structure." Thesis, This resource online, 1988. http://scholar.lib.vt.edu/theses/available/etd-04122010-083702/.
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Cui, Futong. "Biomimetic studies related to lignin degradation." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/30993.
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Lignin is the second most abundant biopolymer on Earth. It is an amorphous, cross-linked, aromatic polymer composed of phenylpropanoid units. There has been an ever growing interest in the biodegradation of this complex polymer for the last 30 years. White-rot fungi have been found to be an important lignin degraders in the natural environment. With the discovery of two groups of hemoprotein enzymes, lignin peroxidases and manganese(II)-dependent peroxidases, from the lignin degrading culture of a white-rot fungus, Phanerochaete chrysosporium, rapid progress has been made in understanding the mechanism of lignin biodegradation.
Synthetic metaUoporphyrins, the iron(III) and manganese(III) complexes of meso-tetra(2,6-dichloro-3-sulfonatophenyl)porphyrin (TDCSPPFeCl and TDCSPPMnCl) and meso-tetra(2,6-dichloro-3-sulfonatophenyl)-B-octachloroporphyrin (Cl₁₆TSPPFeCl and Cl₁₆TSPPMnCl), were used in this study to mimic the functions of the "lignin degrading" enzymes. Factors affecting the catalytic activities of these biomimetic catalysts were studied. TDCSPPFeCl could closely mimic lignin peroxidase in the degradation of a number of lignin model compounds, including veratryl alcohol, B-l, B-O-4, B-5, 5-5' biphenyl, phenylpropane, and phenylpropene model compounds. The reactions catalyzed by TDCSPPFeCl include benzyl alcohol oxidation, C[formula omitted],-C[formula omitted] side chain cleavage, demethoxylation, aromatic ring cleavage, benzylic methylene hydroxylation, and C[formula omitted]-C[formula omitted] double bond hydroxylation (glycol formation). Novel solvent incorporated compounds isolated from the oxidation of veratryl alcohol give insights about the site of attack of substrate cation radical by solvent molecules. The isolation of a solvent incorporated product from the oxidation of a phenylpropene model compound suggests a cation radical mechanism for the oxidation of this lignin substructure. The formation of
a number of direct aromatic ring cleavage products during the oxidation of some model compounds supports the previously proposed mechanism of aromatic ring cleavage. TDCSPPFeCl was also able to catalyze the oxidation of environmental pollutants such as pyrene and 2,4,6-trichlorophenol.
Veratryl alcohol and manganese(II)-complexes have been suggested to function as redox mediators for lignin biodegradation. Evidence has been provided to demonstrate their mediating power during electrochemical and biomimetic degradation of lignin model compounds.
In addition to the mechanistic information obtained, the successful oxidation of the model compounds suggests that metalloporphyrins can be important catalysts for the pulp and paper industry and for pollution control.Science, Faculty of
Chemistry, Department of
Graduate
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Zhu, Hui. "Plasticized lignin-PVC blends for flooring." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0017/MQ54313.pdf.
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Wadenbäck, Johan. "Lignin studies of transgenic Norway spruce /." Uppsala : Dept. of Plant Biology and Forest Genetics, Swedish University of Agricultural Sciences, 2006. http://epsilon.slu.se/200664.pdf.
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Holmgren, Anders. "Biochemical Control Aspects in Lignin Polymerization." Doctoral thesis, Stockholm Stockholm : KTH, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4632.
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