Littérature scientifique sur le sujet « Lignine sulfatée »

Eucalyptus nitens wood samples were subjected to consecutive stages of hydrothermal processing for hemicellulose solubilization and delignification with an ionic liquid, i.e., either 1-butyl-3-methylimidazolium hydrogen sulfate or triethylammonium hydrogen sulfate. Delignification experiments were carried out a 170 °C for 10–50 min. The solid phases from treatments, i.e., cellulose-enriched solids, were recovered by centrifugation, and lignin was separated from the ionic liquid by water precipitation. The best delignification conditions were identified on the basis of the results determined for delignification percentage, lignin recovery yield, and cellulose recovery in solid phase. The lignins obtained under selected conditions were characterized in deep by 31P-NMR, 13C-NMR, HSQC, and gel permeation chromatography. The major structural features of the lignins were discussed in comparison with the results determined for a model Ionosolv lignin.

For the first time, the process of birch ethanol lignin sulfation with a sulfamic acid-urea mixture in a 1,4-dioxane medium was optimized experimentally and numerically. The high yield of the sulfated ethanol lignin (more than 96%) and containing 7.1 and 7.9 wt % of sulfur was produced at process temperatures of 80 and 90 °C for 3 h. The sample with the highest sulfur content (8.1 wt %) was obtained at a temperature of 100 °C for 2 h. The structure and molecular weight distribution of the sulfated birch ethanol lignin was established by FTIR, 2D 1H and 13C NMR spectroscopy, and gel permeation chromatography. The introduction of sulfate groups into the lignin structure was confirmed by FTIR by the appearance of absorption bands characteristic of the vibrations of sulfate group bonds. According to 2D NMR spectroscopy data, both the alcohol and phenolic hydroxyl groups of the ethanol lignin were subjected to sulfation. The sulfated birch ethanol lignin with a weight average molecular weight of 7.6 kDa and a polydispersity index of 1.81 was obtained under the optimum process conditions. Differences in the structure of the phenylpropane units of birch ethanol lignin (syringyl-type predominates) and abies ethanol lignin (guaiacyl-type predominates) was manifested in the fact that the sulfation of the former proceeds more completely at moderate temperatures than the latter. In contrast to sulfated abies ethanol lignin, the sulfated birch ethanol lignin had a bimodal and wider molecular weight distribution, as well as less thermal stability. The introduction of sulfate groups into ethanol lignin reduced its thermal stability.

In this work, we optimized the process of sulfating abies ethanol lignin with complexes of sulfuric anhydride with pyridine and 1,4-dioxane. Experimentally found are the conditions for the implementation of the process of sulfation of abies ethanol lignin by complexes of sulfur trioxide with 1,4-dioxane and pyridine, providing a high sulfur content (12.0–12.6%). It was shown that a high sulfur content of 12.0–13.5% (mass.) in the obtained ethanol lignin sulfate is achieved when the ratio of the amount of chlorosulfonic acid to the amount of abies ethanol lignin is 20.22 : 1 mmol : g and the duration of the sulfation process is 60–120 min and independent of the nature of the sulfating complex. The structure and composition of water-soluble sulfated abies ethanol lignin are confirmed by FTIR spectroscopy, gel permeation chromatography and elemental analysis. In the FTIR spectra of sulfated abies ethanol lignin, in comparison with the FTIR spectra of the initial abies ethanol lignin, there are absorption bands in the region of 1270–1260, 1220–1212, 861–803 cm-1, corresponding to vibrations of sulfate groups. Compared to the initial lignin, sulfated abies ethanol lignin has a low degree of polydispersity. In particular, there was an increase in Mw c ~1.5 kDa to ~3.4 kDa in lignin sulfated for 30 min and a decrease in polydispersity from 2.59 to 1.22 compared to the initial abies ethanol lignin. With an increase in the sulfation time, the profile of the molecular mass distribution curve shifts to a high molecular weight region, with a simultaneous increase in polydispersity to 1.5 and Mw increases to ~4.3 kDa.

The effect of zinc sulfate and ferric sulfate on the pyrolysis process of lignin was studied at three different heating rates by using the thermogravimetric analysis technique. It was found that the pyrolysis of pure lignin is barely affected with the change of heating rates between 10 to 100 °C/min, which is unexpected because of the kinetic nature of pyrolysis. The pyrolysis kinetics of this major component of biomass was studied by using three fitting methods: the differential method with reaction order model n, the isoconversional method, and the distribution of activation energies model, DAEM. The best fit, which allowed calculating acceptable kinetic parameters, was obtained using the last method. The results show the influence of the catalysts and the heating rate on the lignin pyrolysis processes in the presence of the sulfates under study, which is confirmed by obtaining different kinetic parameters. The results suggest that zinc sulfate and ferric sulfate change the kinetic mechanism of lignin pyrolysis.

Ionic liquids (ILs) based on 1-butyl-3-methylimidazolium (bmim) cation have proved to be promising solvents for the fractionation of plant biomass with the production of cellulose and lignin. This study deals with the characterization of lignins isolated from coniferous (spruce) wood using [bmim]OAc and [bmim]MeSO4 ionic liquids and their binary mixtures with DMSO (80:20). Molecular weight distributions, functional composition, and structural features of IL lignins were studied by size-exclusion chromatography, NMR spectroscopy (1D and 2D) and atmospheric pressure photoionization high-resolution mass spectrometry. It was shown that the interaction of ILs with lignin leads to significant chemical changes in the biopolymer; a decrease in the degree of polymerization and in the content of free phenolic hydroxyl groups due to alkylation, the disappearance (in the case of [bmim]OAc) of carbonyl groups and a significant destruction of β-O-4 bonds. The chemical reactions between lignin and 1-butyl-3-methylidazolium cation with covalent binding of ionic liquids or products of their decomposition is evidenced by the presence of a large number of nitrogen-containing oligomers in IL lignins.

Recurriendo al uso de la técnica análisis termogravimétrico, se estudió el efecto del sulfato de zinc y del sulfato férrico en el proceso de pirólisis de la lignina a tres velocidades de calentamiento. Se encontró que la pirólisis de la lignina pura se afecta muy poco con el cambio de las velocidad de calentamiento entre 10 y 100 °C/min, lo cual es inesperado por la naturaleza cinética de la pirólisis. La cinética de pirólisis de este componente de la biomasa fue estudiada teniendo en cuenta tres métodos de ajuste: el método diferencial con modelo de orden de reacción n, el método isoconversional y el modelo de distribución de energías de activación, DAEM. Los mejores ajustes, que permitieron calcular parámetros cinéticos aceptables, fueron obtenidos usando el último método. Los resultados evidencian la influencia de los catalizadores y de la velocidad de calentamiento en los procesos de pirólisis de la lignina en presencia de los sulfatos de estudio, que se confirma con la obtención de diferentes parámetros cinéticos. En términos generales, los sulfatos de zinc y férrico retardan el proceso de pirólisis de la lignina. Los resultados sugieren que los sulfatos de zinc y férrico cambian el mecanismo cinético de la pirólisis de la lignina.

Physcomitrium (Physcomitrella) patens is a bryophyte highly tolerant to different stresses, allowing survival when water supply is a limiting factor. This moss lacks a true vascular system, but it has evolved a primitive water-conducting system that contains lignin-like polyphenols. By means of a three-step protocol, including ammonium sulfate precipitation, adsorption chromatography on phenyl Sepharose and cationic exchange chromatography on SP Sepharose, we were able to purify and further characterize a novel class III peroxidase, PpaPrx19, upregulated upon salt and H2O2 treatments. This peroxidase, of a strongly basic nature, shows surprising homology to angiosperm peroxidases related to lignification, despite the lack of true lignins in P. patens cell walls. Moreover, PpaPrx19 shows catalytic and kinetic properties typical of angiosperm peroxidases involved in oxidation of monolignols, being able to efficiently use hydroxycinnamyl alcohols as substrates. Our results pinpoint the presence in P. patens of peroxidases that fulfill the requirements to be involved in the last step of lignin biosynthesis, predating the appearance of true lignin.

Soda lignin is a by-product of the soda process for producing cellulose from grassy raw materials. Since a method for the industrial processing of lignin of this type is still lacking, several research teams have been working on solving this problem. We first propose a modification of soda lignin with sulfamic acid over solid catalysts. As solid catalysts for lignin sulfation, modified carbon catalysts (with acid sites) and titanium and aluminum oxides have been used. In the elemental analysis, it is shown that the maximum sulfur content (16.5 wt%) was obtained with the Sibunit-4® catalyst oxidized at 400 °C. The incorporation of a sulfate group has been proven by the elemental analysis and Fourier-transform infrared spectroscopy. The molecular weight distribution has been examined by gel permeation chromatography. It has been demonstrated that the solid catalysts used in the sulfation process causes hydrolysis reactions and reduces the molecular weight and polydispersity index. It has been established by the thermal analysis that sulfated lignin is thermally stabile at temperatures of up to 200 °C. According to the atomic force microscopy data, the surface of the investigated film consists of particles with an average size of 50 nm. The characteristics of the initial and sulfated β-O-4 lignin model compounds have been calculated and recorded using the density functional theory.

Polyethylene glycol (PEG) is a low-cost and advantageous embedding medium, which maintains the majority of cell contents unaltered during the embedding process. Some hard or complex plant materials are better embedded in PEG than in other usual embedding media. However, the histochemical tests for phenolics and lignins in PEG-embedded plant tissues commonly result in false negatives. We hypothesize that these false negatives should be prevented by the use of distinct fixatives, which should avoid the bonds between PEG and phenols. Novel protocols for phenolics and flavanols detection are efficiently tested, with fixation of the samples in ferrous sulfate and formalin or in caffeine and sodium benzoate, respectively. The differentiation of lignin types is possible in safranin-stained sections observed under fluorescence. The Maule’s test faultlessly distinguishes syringyl-rich from guaiacyl- and hydroxyphenyl-rich lignins in PEG-embedded material under light microscopy. Current hypothesis is corroborated, that is, the adequate fixation solves the false-negative results, and the new proposed protocols fill up some gaps on the detection of phenolics and lignins.

AbstractA novel lignin-based slow release fertilizer with low environmental impact has been developed. More precisely, a granulated simple superphosphate fertilizer, consisting of calcium phosphate monobasic [Ca(H2PO4)2·H2O] and gypsum (CaSO4·2H2O) was coated with modified kraft lignins and the diffusion of phosphorus was observed as a function of time. The lignin was hydroxymethylated with formaldehyde and subsequently cross-linked with phenol-formaldehyde resin resulting in HML-PF as coating. Moreover, coating films were prepared from a mixture of acetylated lignin (Lac) and acetylated cellulose (Cellac). Both coatings show similar permeability to calcium phosphate and controlled effectively the P-release, particularly at the initial stages of the experiment. The P-release was linear in the decay phase but there is no lag time in the process. A significant P amount was not released from the particles coated with HML-PF, i.e. 80–50% remained irreversible bound, depending on the coating formulation. The maximum fractional P-release varied among the different coatings tested. Phosphorus is partly retained inside the slightly soluble calcium sulfate matrix.

Ce travail sur l’amélioration de la protection solaire suivant un concept éco-participatif propose 2 parties, (i) l’élaboration d’une formulation simple, (ii) la synthèse d’une mélanine de substitution. La formulation contient seulement 8 ingrédients, dont 2 filtres organiques sélectionnés sur leur photostabilité, caractéristiques physicochimiques, et l'absence d'impact (santé, écosystèmes), le BEMT et le DHHB. Une protection totale est atteinte par l’addition de lignine sulfatée (LiS), polymère largement disponible, non toxique, antiradicalaire et soluble dans l’eau. Des méthodologies expérimentales ont permis de minimiser les concentrations, débouchant sur 2 formules stables, SPF30 et SPF50, contenant respectivement 9 et 12% de filtres, et 5% de LiS chacune. De l'effet booster observé, des hypothèses sur les interactions LiS-filtres sont émises. La deuxième partie concerne la production de pyomélanine. Alors que les quantités produites par les microorganismes restent faibles, 3 procédés sont comparés: une autooxydation du HGA-Mn2+ (rendement 0,317 g/g de substrat), une culture induite d’Halomonas titanicae (0,55 g/L), et une polymérisation par une laccase (PyoENZ, 1,25 g/g). Les 3 structures ont été caractérisées par 13C RMN (CP-MAS) et FTIR, une réaction de décarboxylation biologique partielle conduit à la formation d'alcool gentisique et de gentisaldéhyde incorporés dans le polymère. PyoENZ est hyperthermostable, non (photo)cytotoxique, piège les ROS, réduit efficacement le Fe3+, et est proposée pour des applications
This work on the improvement of solar protection according to an eco-participatory concept proposes 2 parts, (i) the elaboration of a simple formulation, (ii) the synthesis of substitute melanin. The formulation contains only 8 ingredients, including 2 organic filters selected on their photostability, physicochemical characteristics, and absence of impact (health, ecosystems), BEMT and DHHB. Total protection is achieved by the addition of lignosulfonate (LiS), a widely available, non-toxic, anti-free radical, and a water-soluble polymer. Experimental design allowed to minimize the concentrations, resulting in 2 stable formula, SPF30 and SPF50, containing 9 and 12% filters respectively, and 5% LiS each. From the observed booster effect, hypotheses on LiS-filter interactions were proposed. The second part concerns the production of pyomelanin. While the quantities produced by the microorganisms remain low, 3 processes are compared: autooxidation of HGA-Mn2+ (yield 0.317 g/g substrate), an induced culture of Halomonas titanicae (0.55 g/L), and a method based on a laccase polymerization (PyoENZ, 1.25 g/g). The 3 structures had been characterized by 13C NMR (CP-MAS) and FTIR, a partial biological decarboxylation reaction was occurred and led to the formation of gentisic alcohol and gentisaldehyde which are incorporated in the polymer. PyoENZ is hyperthermostable, non-(photo)cytotoxic, traps ROS, effectively reduces Fe3+, and is proposed for applications

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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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
The processes of separation and isolation of Kraft lignin obtained have been insufficiently resear ched, since much of the lignin of liqueurs obtained industrially is burned for energy recovery and carbon sources in the industrial processes. Currently, with the technological innovation targeting the pulp and paper industries, it is increasingly importan t to obtain lignin in simple and economically viable way. In addition, it is very important to find conditions under which the proceedings begin minimum degradation into lignin structures. In this work, the concentrated liquor lignin from Kraft pulp proces s was precipitated in acid medium in different conditions of pH and variable times of exposure to acid conditions of precipitation. It was done later, ash analysis, calorific power, Scanning Electron Microscopy with X - ray Spectroscopy (SEM/EDS); Fourier Tr ansform Infrared Spectroscopy (FTIR) and Ultraviolet - Visible Spectrophotometry precipitated (UV - VIS) for the characterization of the lignins and the filtered, for the characterization of the soluble fractions. A general analysis of the results showed that the best yield has occurred in 15 minutes of precipitation time for the pH of 6.71 (less acidic) among all employees. In the second test, the precipitations were performed at pH 2, 4 and 6 and with a time of 5 and 15 minutes, in which was got better yields and lower salt content in lignin. It has been applied statistical analysis in all the results, which many of them were considered equal. Thus, the best case was considered carried out at pH 6 at the time of 5 minutes , since it uses less hydrochloric acid are to perform precipitation. In parallel, it has been done tests to assess the possibility of separate fragments of lignin and sugars. The preliminary tests were conducted with phenol, simulating the lignin, and glucose, simulating the sugars. In order t o carry out this separation was used cellulose acetate Hydrogel as stationary phase in a preparative scale. In the first test conducted in a time of 30 minutes, it was possible to observe that there was a clear separation of phenol and glucose. In the seco nd test, in which the parameters were refined, like the elution time (55 minutes), it was possible to note a great improvement in the separation. The test of fractionation was carried out in order to simulate future tests to improve the conditions of ferme ntation of residual sugar produced by hydrolysis of cellulose waste involved in the production of second - generation ethanol.
Os processos de separação e isolamento da lignina kraft obtidas são pouco estudadas, uma vez que grande parte da lignina de licores obtidos industrialmente é queimado para recuperação de energia e fontes de carbono nos processos industriais. Atualmente, com a inovação tecnológica voltada para as indústrias de papel e celulose, torna - se cada vez mais importante a obtenção de lignina de forma simples e economicamente viável. Além disso, é muito importante que as condições do processo provoquem mínimas degradações nas estruturas da lignina. Neste trabalho, a lignina a partir da pasta de lixívia concentrada do processo kraft foi precipitada em meio ácido, em diferentes condições de pH e tempos de exposição variáveis a condições ácidas da precipitação. Posteriormente foi realizado análise de cinzas, poder calorífico, microscopia eletrônica de varredura com detector de energia dispersa de raio s - x (MEV/EDS), espectroscopia de infravermelho por transformada de Fourier (FTIR) e espectrofotometria no ultravioleta - visível (UV - VIS). Os precipitados foram empregados na caracterização das ligninas e os filtrados, na caracterização das frações solúveis. A análise geral dos resultados mostrou que o melhor rendimento ocorreu em 15 minutos de tempo de precipitação para o pH de 6,71 (menos ácida) entre todos os processos. No segundo teste as precipitações foram realizadas em pH 2, 4 e 6 e com tempo de 5 e 15 minutos, nas quais se obtiveram melhores rendimentos e menores teores de sais na lignina. Foi aplicada análise estatística em todos os resultados. A condição mais eficaz foi obtida em pH 6 no tempo de 5 minutos. Em paralelo, foram realiza dos os testes para avaliar a possibilidade de separação de fragmentos de lignina e açúcares. Os testes preliminares foram realizadas com fenol, simulando a lignina, e glicose, simulando os açúcares. Para realizar esta separação foi usado acetato de celulos e hidrogel como fase estacionária em uma escala preparativa. No primeiro teste realizado em um tempo de 30 minutos, foi possível verificar a separação de fenol e glicose. No segundo teste, em que os parâmetros foram refinados, como o tempo de eluição (55 minutos), foi possível ver uma grande melhoria na separação. O teste de fracionamento foi realizado, a fim de simular ensaios futuros para melhorar as condições de separação dos açúcares residuais produzidos pela hidrólise de resíduos de celulose envolvido na produção de etanol de segunda geração.

Les lignines sont des polymères naturels et renouvelables. C’est le polymère le plus abondant sur la terre après la cellulose. De nos jours, les lignines sont sous-exploitées et seulement 2 % de la lignine est valorisée par an, leur application capital restant comme combustible dans les industries papetières pour la production d'énergie. Au Québec, 130 000 tonnes de liqueur noire contenant de la lignine pourraient être extraites par an afin de les valoriser, sans perturber la production dans ces industries papetières. Sa valorisation pourrait contribuer à créer de nouveaux produits à valeur ajoutée tels que les biocomposites avec une matrice de polyéthylène, polystyrène recyclé ou encore le bois. Ces nouveaux produits de ces industries pourraient améliorer la situation économique dans ce domaine, mais aussi pourraient apporter de nouvelles connaissances dans le domaine des écomatériaux tout en contribuant à la diminution des gaz à effet de serre en favorisant le produit naturel contre le produit de synthèse. Les structures des lignines diffèrent selon certains paramètres (origine, le processus d'isolation ...). Dans ce projet, deux lignines Kraft seront précipitées à partir de liqueur noire de deux industries papetières québécoises en utilisant du dioxyde de carbone comme réactif. Ces lignines seront purifiées et comparées analytiquement à d’autres lignines; une lignine Kraft commerciale, une lignine pyrolytique et une lignine Protobind Soda 2400. Connaissant la structure des lignines, il sera plus facile de les modifier. Les lignines Kraft ont été estérifiées avec l'anhydride maléique et l'anhydride succinique et comparée aux lignines non modifiées par plusieurs techniques d'analyse telles que FT-IR, TGA, DSC, RMN. Les lignines Wayagamack maléatées et non maléatées ont été incorporées dans un biocomposite de polystyrène recyclé et les propriétés mécaniques et thermiques ainsi que la morphologie ont été étudiées. Les composites avec la lignine non modifié ont montré de bonnes propriétés mécaniques et thermiques par rapport au composite avec la lignine maléate où la lignine maléatée était pourtant compatible avec le polystyrène recyclé. Les lignines Windsor non estérifiée et succinate ont été utilisées en tant que liant dans un panneau de bois et leurs propriétés mécaniques ont également été étudiées. Les résultats ont montré les meilleures propriétés mécaniques pour le panneau de bois contenant de la lignine Kraft non modifié. Les réactions de condensation de la lignine Kraft au cours de la compression à chaud du panneau améliorerait la solidité du panneau contrairement à des réactions d'estérification qui pourraient avoir lieu entre la lignine estérifié et les hydroxyles de bois. Mots clés : Liqueur noire, Lignine, Procédé Kraft, Estérification, Caractérisation, Composite, Valorisation, polystyrène, bois.
Lignins are renewable and natural polymers. It is the most abundant polymer on the earth after cellulose. Nowadays, lignins are not fully exploited and only 2% of lignin is valorised per year, their principal application remaining as a combustible in pulp industries for energy production. In Quebec, 130000 tons of black liquor containing lignin could be available from Kraft industry, per year, in order to valorise them, without disturbing the mill production. Its valorisation could contribute to create new value added products like bio composites with a matrix of polyethylene, recycled polystyrene or even wood. These new products of these industries could improve the economic situation in this field, but also could bring new knowledge in the eco materials field, in contributing of the decrease of greenhouse gases in favoring the natural product against the synthetic product. Lignin structure is different depending on several parameters (origin, isolation process…). In this project, two Kraft lignins will be precipitated from black liquor of two Quebecoise paper industries using carbon dioxide as the reagent. These lignins will be purified and compared analytically to others lignins; one Kraft softwood commercial lignin, one pyrolytic lignin and one Soda lignin Protobind 2400. With the knowledge of the Kraft lignin structure, it will be easier to modify these lignins. The esterified Kraft lignins with maleic anhydride and succinic anhydride will be compared to the unmodified lignin according to several analytical technical as FT-IR, TGA, DSC, NMR. Maleated and non modified Wayagamack lignins were incorporated in biocomposite of recycled polystyrene and the mechanical and thermal properties and the morphology were studied. The composite with non modified lignin showed good mechanical and thermal properties compared to the composite with maleated lignin where the maleated lignin was still compatible with the recycled polystyrene The Windsor succinated and non modified lignin were used as a binder in a wood panel and their properties were also studied. The results showed the best mechanical properties for the wood panel containing non modified Kraft lignin. Condensation reactions of Kraft lignin during the hot-pressing of the panel improve the solidity of the panel unlike esterification reactions that could take place between esterified lignin and the wood hydroxyls. Key words: Black liquor, Lignin, Kraft process, Characterisation, Esterification, Composite, Valorization, Polystyrene, Wood.

Orientadores: Rubens Maciel Filho, Eduardo Coselli Vasco de Toledo
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica
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Resumo: Em nível global, a indústria de celulose e papel está começando a experimentar os beneficios dos recentes desenvolvimentos na área de modelagem e controle de processos.Técnicas avançadas de simulação e controle oferecem ferramentas que permitem a análise e o projeto eficiente para processos multivariáveis não lineares e que envolvem o projeto, a inferência, a otimização e o controle automático do processo. A indústria de celulose utiliza cozinhadores, conhecidos como digestores, que são vasos de pressão onde os cavacos de madeira são tratados com licor de cozimento (hidróxido de s ódio e sulfeto de sódio) de composição determinada, a pressão e temperatura estabeleci das, visando a produção de polpa celulósica. Dentro deste contexto, os digestores podem ser classificados como contínuo (Kamyr) e descontínuo (Batch). O objetivo deste trabalho é estudar o processo de obtenção da polpa celulósica a partir da análise dos principais fenômenos fisico - químicos que ocorrem em um digestor kraft descontínuo. As predições a partir do modelo utilizado (Mirams e Nguyen, 1994) permitem a avaliação do comportamento dinâmico e a análise da sensibilidade paramétrica do processo, observando-se quais os parâmetros operacionais e as variáveis do processo que mais influenciam o comportamento do reator. O modelo do digestor descontínuo considera a difusão nos poros da madeira iniciada durante a impregnação dos cavacos. Outra característica do modelo é a sua adaptação de modo a considerar as reações de deslignificação como reações simultâneas de três diferentes tipos de lignina, sendo que a mais reativa reage mais rapidamente. Esta abordagem apresenta um novo ponto de vista para a teoria das três fases da reação, uma vez que seus resultados podem ser interpretados como se a reação de cada lignina fosse responsável por uma fase específica da reação (deslignificação inicial, principal e residual). Com relação à solução do modelo, esta foi baseada no Método das Linhas, a qual consiste na utilização do Método da Colocação Ortogonal para a discretização das equações parciais do modelo. A integração temporal das equações diferenciais ordinárias foi resolvida pelo integrador LSODE, (V asco de Toledo, 1999). Os resultados obtidos pelo modelo reproduziram as principais características dinâmicas do sistema, possibilitando compreender as etapas principais na obtenção da celulose sob determinadas condições operacionais do digestor. Isso permite a sua utilização para estudos de controle, otimização e projeto de reator descontínuos de forma segura e eficiente
Abstract: Global1y, the Kraft pulping process is beginning to get use of the benefits of the recent developments in the modeling area and process control. Advanced techniques of simulation and control offer tools that allow the analysis and efficient design of multivariable non-linear process, involving the optimization and the advanced control of the process. The pulp industry uses some equipment named digesters, which are pressure vessels where the chip of wood are treated with cooking liquor (sodium hydroxide and sodium sulfide) with defined composition, established pressure and temperature, aiming to the cellulosic pulp production. In this context, the digesters can be c1assified as continuous (Kamyr) and discontinuous digester (Batch). The aim of this work is to study the production process of the cellulosic pulp from the analysis of the Physical-Chemical Phenomena that occur in a discontinuous kraft digester. The predictions from the considered model (Mirams e Nguyen, 1994) allow the evaluation of the dynamic behavior and the analysis of the parametric sensitivity of the process, observing which is the operational parameter and variable of process that influence the most reactor behavior. The model for a descontinuous digester considers the diffusion into the wood pores initiated during the impregnation of the chips. Another characteristic of the model is its adaptation in order to consider the delignification reactions as simultaneously reactions with three different types of lignin, with the most reactive lignin reacting more quickly. This approach present a new point of view for the theory of three phases of the reaction, interpreting its results as if the reaction qf each lignin was responsible for a specific phase of the reaction (initial delignification, bulk and residual). Regarding the solution of the model it was based on "Line Method", which consist on usaged of Orthogonal Collocation for discretization of the partial differential equations. The temporal integration of the ordinary differential equations was solved by integrator LSODE (Vasco de Toledo, 1999). The obtained results from the model reproduced the main dynamic characteristics of the system, making possible the knowledge of the main stages in the production of the cellulose under determined operational conditions of the digester. These results can them be used in control, optimization and design studies in a safe and efficient way
Mestrado
Desenvolvimento de Processos Químicos
Mestre em Engenharia Química

The herpes virus family consists of more than hundred members that infect organisms, of which eight, differing markedly in the biology are known to infect humans. HSV- I is the most common one, causing oral lesions and sporadic encephalitis. These infections are highly prevalent affecting at least one in three individuals in the United States.The entry of the herpes virus into the cell is a two-step process. The initial step involves the cell surface heparan sulfate and glycoproteins in the viral envelope which enables the virus to penetrate into the cell. The second step is the fusion step. Depending on the nature of interaction and size of HS chain, a single chain may bind multiple viral ligands on a virion. There is substantial evidence showing that HS plays an important role in viral binding.HS is a heterogeneous, linear sulfated oligosaccharide composed of alternating glucosamine and uronic acid residues, which could specify distinct receptor for various viral ligands. HS, present on most exposed cell surfaces, make an ideal snare for the capture of most herpes viruses and may facilitate subsequent interactions with other co-receptors required for entry. Number of viruses, including HSV- I, HSV- II, HIV- I and dengue virus use sites of HS as receptors for binding to cells. Recently 2000 Liu et.al have characterized a HS based octasaccharide that binds to HSV-I gD. The distinguished feature in the composition of the octasaccharide is the presence of 3-O-sulfate glucosamine residue, which is an uncommon structural modification in HS. Its presence in the HSV-I gD binding sequence may confer specificity of interaction and assist HSV-I entry into the cell.Numerous sulfated molecules have been explored as mimics of HS in the inhibition of HSV-1 entry into cells. To date, most of the sulfated molecules screened for anti-viral activity have been carbohydrates. So, we reasoned that it should be possible to mimic critical interactions of HS with one or more viral glycoprotein using synthetic, non-polysaccharide, sulfated compounds. Further, it may be possible to mimic specific sequence(s) in HS, which play a role in HSV infection, with small synthetic, sulfated, non-carbohydrate molecules. In a search for synthetic mimics of HS as inhibitors of HSV-I infection, we screened a small, synthetic, sulfated flavonoids to discover a potent inhibitory activity arising from sulfation of a macromolecule present as an impurity in a crude natural product.The active principle was identified through an array of biophysical and chemical analyses as lignin sulfate, a heterogeneous; polydisperse network polymer composed of substituted phenylpropanoid monomers. Further, LC-MS with APCI in negative ionization mode, which have been reported in here for the first time for analysis of lignin, has been successfully used to deduce oligomeric structures present in the precursor of the active macromolecule based on the spectrum of the depolymerized lignin. This corroborates well with the structural information obtained using other analytical techniques. We hypothesize that the structural heterogeneity and polydispersity of lignin coupled with optimal combination of sulfate charge and hydrophobicity result in high potency. Given that the native lignin is inactive, lignin sulfate discovered here provides a variety of organic scaffolds that with the critical sulfate groups in space can mimic the HSV-I gD binding sequence.

Anticoagulants are used as the first line therapy for management and prevention of thrombotic disorders. Thrombin and factor Xa have been the prime targets for regulation of the coagulation cascade. In this work, a small library of 17 benzofuran derivatives were synthesized and screened against thrombin and factor Xa. The derivatives that displayed inhibitory potential were docked on the exosite-II of factor Xa using a docking protocol that was developed in our research group. These compounds were based on the β-5 structural unit found in the oligomer -'CDSO3‘, which was prepared in our lab and was found to inhibit both thrombin and factor Xa by an exosite-II mediated allosteric disruption of the catalytic triad.The results revealed that these β-5 like derivatives are inhibitory against thrombin and factor Xa, although their potency is weak. Thrombin and factor Xa appear to recognize different structural features suggesting a significant selectivity in recognition. Furthermore, a slight preference for the benzofuran scaffold was observed with factor Xa. Probing the mechanism of inhibition using Michaelis-Menten kinetics reveal that these compounds display uncompetitive inhibition of these proteases and the mechanism of inhibition is allosteric. Docking of these compounds on factor Xa were done using GOLD (Genetic algorithm for ligand docking) and the results, explain the observed inhibition profile. The computed docked poses also give an idea of the residues on the exosite-II of factor Xa critical for inhibition. The molecules studied here are radically different in terms of structure and mechanism of inhibition from any other ligand described in literature. This represents an opportunity to discover novel molecules with a possibly different pharmacological and toxicological profile.

Bagasse is scientifically defined as waste from the extraction of sugarcane liquid after the grinding process. Bagasse is biomass which is used as raw material to be processed into surfactants. Bagasse fiber cannot be dissolved in water because it consists mostly of cellulose, pentosane and lignin. The optimum conditions for obtaining the highest yield and the best conversion of bagasse to lignin were achieved when used 80 mesh bagasse and 3 M NaOH as a hydrolysis agent. Then lignin is reacted with 0.25 sodium bisulfite to the surfactant sodium lignosulfonate. Lignin and sodium lignosulfonate were further characterized using a FTIR spectrophotometer to determine the components contained therein. The lignin component consists of phenolic functional group elements, aliphatic and aromatic groups, ketone groups, aren functional groups, amine groups and alkyl groups along with standard lignin components. Likewise with lignosulfonates, with indicator components consisting of C═C alkenes, Sulfate S═O, C═O carboxylic acids and S-OR esters. The NMR test was resulted the monomer structure of SLS surfactant bagasse. The results indicate that the lignin isolation process from bagasse has been successfully. Likewise, the sulfonation of lignin to lignosulfonate is also successful.

Anionic surfactants are generally used in surfactant injections because they are good, resistant in storage and stable. Furthermore, Commercially, anions are produced in the form of carboxylates, sulfates, sulfonates, phosphates, or phosphonates. The surfactants used in the process of implementing Enhanced Oil Recovery (EOR) are generally petroleum-based, such as Petroleum Sulfonate. Therefore, an increase in oil price, leads to an increase in the price of surfactant and the operational costs becomes relatively expensive. Lignosulfonate is a type of anionic surfactant which is made with lignin as raw material. This lignin is found in many plants, including wood stalks, plant leaves, peanut shells, corn cobs, bagasse, empty bunches of oil palm and wheat straw. Based on the results of previous studies, 25% of lignin component was discovered in bagasse. This may be a consideration that there is enough lignin in bagasse to be used as raw material in the production of lignosulfonate vegetable surfactants. Furthermore, lignin from bagasse is used because bagasse is easy to obtain, cheap and an environmental friendly vegetable waste. Currently, bagasse is only used as fuel in steam boilers and papermaking, cement and brick reinforcement, a source of animal feed, bioethanol, activated charcoal as adsorbent and compost fertilizer. This is a consideration to optimize the use of bagasse to become lignosulfonate as an alternative for surfactants in the petroleum sector. The purpose of this study is to show that lignin from bagasse has the potential of becoming a lignosulfonate surfactant. There are several studies that have processed bagasse into sodium lignosulfonate. The component test on the results showed that the surfactant component of sodium lignosulfonate from bagasse was almost the same as the commercial standard lignosulfonate component. Furthermore, the results of the HLB (Hydrophilic–Lipophilic Balance) value test show that the sodium lignosulfonate surfactant from bagasse can function as an emulsion form which is a required parameter for the surfactant injection mechanism. Based on the discussion of the study results, bagasse has the potential as a raw material to be processed into lignosulfonates.

Aging is a natural phenomenon that occurs due to diverse changes in cells and tissues over time, and it is impossible to halt or reverse the process. However, extrinsic skin aging, caused by environmental factors, is largely preventable. Natural products have long been used in skin anti-aging treatments. Seaweeds are multicellular, large-sized marine organisms that have a variety of economic values. They are used in cosmetics, cosmeceuticals, and nutricosmetics due to their versatility and richness in valuable bioactive compounds and other nutrients found in different species of seaweed. This category includes phenolic compounds [flavonoids (flavones, flavanols, flavanones, flavonols, anthocyanins, isoflavones); non-flavonoids (tannins, phlorotannins, lignans & stilbenes)], polysaccharides (sulfated galactans, ulvan, sulphuric acid polysaccharides, alginic acid, carrageenans, fucoidan or sulfated fucose, laminarin), peptides and amino acids, fatty acids (docosahexaenoic acid, eicosapentaenoic acid, stearidonic acid and eicosatrienoic acid), vitamins (vitamin B: B1, B2, B3, B5, B6 & B8, vitamin C, vitamin E), vitamin precursors (α-tocopherol, βcarotene, lutein, and zeaxanthin), pigments (chlorophylls, xanthophylls, and carotenoids), and minerals. The presence of these important bioactive compounds plays important roles in cosmeceutical applications by mediating antioxidant, photoprotective, anti-wrinkling, anti-inflammatory, antimicrobial, anti-collagenase, anti-elastase, and anti-metalloproteinase activities through multiple pathways. Furthermore, seaweed nutrients play vital roles in nutricosmetics and are also involved in vital technical features such as moisturizing, thickening, gelling, and emulsifying effects in different skincare products. This chapter specifically describes the skin antiaging properties of seaweeds via different biological activities due to their unique composition.