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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Social Media Portrayals of Three Extractives Companies’ Funding of Sport for Development in Indigenous Communities in Canada and Australia

Latino, Steven 29 June 2020 (has links)
The extractives industry (mining, oil, and gas) engages in corporate social responsibility (CSR) activities to reinforce its organizational legitimacy and enhance its public image. One such approach to CSR that is popular in the industry is through funding sport initiatives aimed at Indigenous peoples (often termed Sport for Development; SFD). On the surface, such funding may seem commendable and innocuous; however, questions have been raised about the ways in which such funding may obfuscate the harmful impacts that the extractives industry has had and continues to have on Indigenous peoples and their traditional territories. Through the adoption of a postcolonial theoretical perspective and in conjunction with netnographic methods and discourse analysis, this project involved a consideration of how extractives companies portray their funding of sport programs in Indigenous communities on social media. Given the research focus on Indigenous communities in the countries known as Canada and Australia, between country differences were also examined. Three discourses related to the extractives industry’s funding of SFD in Indigenous communities in Canada and Australia were developed. These discourses included the following: 1) Extractives companies are proud “partners” of Indigenous communities; 2) Extractives companies are committed to helping Indigenous communities in Canada and Australia; and 3) Canadian extractives companies are future focused and past-blind, while Australian extractives companies are advocates for reconciliation. Overall, extractives companies in Canada and Australia were found to use social media to portray themselves as responsible and committed partners of Indigenous communities, while obscuring the ongoing histories of colonialism through discourses of empowerment and development through sport. Suggestions are made regarding ongoing interrogation of the ways in which the extractives industry perpetuates colonialism.
32

The initial phase of sodium sulfite pulping of softwood : A comparison of different pulping options

Deshpande, Raghu January 2016 (has links)
Single stage and two-stage sodium sulfite cooking were carried out on either spruce, pine or pure pine heartwood chips to investigate the influence of several process parameters on the initial phase of such a cook down to about 60 % pulp yield. The cooking experiments were carried out in the laboratory with either a lab-prepared or a mill-prepared cooking acid and the temperature and time were varied. The influences of dissolved organic and inorganic components in the cooking liquor on the final pulp composition and on the extent of side reactions were investigated. Kinetic equations were developed and the activation energies for delignification and carbohydrate dissolution were calculated using the Arrhenius equation. A better understanding of the delignification mechanisms during bisulfite and acid sulfite cooking was obtained by analyzing the lignin carbohydrate complexes (LCC) present in the pulp when different cooking conditions were used. It was found that using a mill-prepared cooking acid beneficial effect with respect to side reactions, extractives removal and higher stability in pH during the cook were observed compared to a lab-prepared cooking acid. However, no significant difference in degrees of delignification or carbohydrate degradation was seen.  The cellulose yield was not affected in the initial phase of the cook however; temperature had an influence on the rates of both delignification and hemicellulose removal. It was also found that the  corresponding activation energies increased in the order:  xylan, glucomannan, lignin and cellulose. The cooking temperature could thus be used to control the cook to a given carbohydrate composition in the final pulp. Lignin condensation reactions were observed during acid sulfite cooking, especially at higher temperatures. The LCC studies indicated the existence of covalent bonds between lignin and hemicellulose components with respect to xylan and glucomannan. LCC in native wood showed the presence of phenyl glycosides, ϒ-esters and α-ethers; whereas the α-ethers  were affected during sulfite pulping. The existence of covalent bonds between lignin and wood polysaccharides might be the rate-limiting factor in sulfite pulping. / The sulfite pulping process is today practised in only a small number of pulp mills around the globe and the number of sulfite mills that use sodium as the base (cation) is less than five. However, due to the increasing interest in the wood based biorefinery concept, the benefits of sulfite pulping and especially the sodium based variety, has recently gained a lot of interest. It was therefore considered to be of high importance to further study the sodium based sulfite process to investigate if its benefits could be better utilized in the future in the production of dissolving pulps. Of specific interest was to investigate how the pulping conditions in the initial part of the cook (≥ 60 % pulp yield) should be performed in the best way. Thus, this thesis is focused on the initial phase of sodium based single stage bisulfite, acid sulfite and two-stage sulfite cooking of either 100 % spruce, 100 % pine or 100 % pine heartwood chips. The cooking experiments were carried out with either a lab prepared or a mill prepared cooking acid and the temperature and cooking time were varied. Activation energies for different wood components were investigated as well as side reactions concerning the formation of thiosulfate. LCC (Lignin carbohydrates complexes) studies were carried out to investigate the influence of different cooking conditions on lignin carbohydrate linkages.
33

Quantification of resin acids, fatty acids and sterols in process and waste water from forest industry / Kvantifiering av hartssyror, fettsyror och steroler i process och avloppsvatten från skogsindustrin

Ismailov, Taner January 2013 (has links)
This work focuses on wood extractives in effluents from the CTMP plant at Skoghall Mill. Pulp and paper industry effluents contain mostly natural compounds which are part of the trees. They are toxic to aquatic life but harmless in nature, as they are present in low concentrations. Processing tons of wood, such as in a pulp mill, strongly increases the concentrations of the toxic compounds (Ali, M. and Sreekrishnan, T., 2001) which have to be treated before transferring to the aquatic environment.Extractives can be found in different forms, as micelles soluble in water, unprocessed in fibers or absorbed on the surface of fibers. It is important to know in which forms extractives are mostly present in the effluent, so that they can be treated more efficiently. It is desired to have extractives absorbed on the fibers and fibrils present in the waste water, so they can be separated from the water and treated separately, e.g. burned for energy recovery. Dissolved extractives complicate the oxygen transfer in an aerated biological treatment step with their surface active properties (Sandberg, 2012).The aim of this study is quantification of extractives on the fibers suspended in the waste water and extractives dissolved in the water. The distribution between the two forms is an important input when designing future effluent treatment. Wood extractives itself are a wide group with different compounds. This work focuses on the main groups present in waste water: resin acids, free and esterified fatty acids and, free and esterified sterols. These groups are analyzed in different process waters and waste water before the waste water treatment plant. The measured concentrations of extractives were as expected, higher in process and effluent waters, lower in white water. Most of the extract was dissolved in the water and unfortunately fiber samples contained very low concentration from the total extract in the samples.
34

Caractérisation fonctionnelle de petites protéines sécrétées chez les champignons lignolytiques / Characterization of small proteins by lignolytic fungi

Valette, Nicolas 06 December 2017 (has links)
Durant ces dernières décennies, les systèmes enzymatiques de dégradation du bois sécrétés par les champignons ont fait l’objet de nombreuses études aboutissant à la caractérisation fonctionnelle et biochimique des enzymes extracellulaires majeures agissant directement sur le polymère. Cependant, les systèmes annexes associés au processus de dégradation n’ont à l’heure actuelle été que peu étudiés. En particulier, les systèmes de détoxication et de réponses des champignons au stress généré par le processus de dégradation ainsi que les mécanismes lui permettant de croître dans cet environnement hostile sont encore peu connus. Ce stress est majoritairement dû à la présence de radicaux et d’extractibles. Les extractibles sont des molécules issues du métabolisme secondaire de l’arbre qui sont synthétisés pour augmenter la durabilité du bois face aux attaques biotiques et abiotiques. Une analyse transcriptomique réalisée au laboratoire a mis en évidence la surexpression de gènes codant des petites protéines sécrétées (SSP) chez Phanerochaete chrysosporium lors d’une culture en présence d’extractibles de chêne. La fonction de ce type de protéines chez les champignons lignolytiques est inconnue. Mon projet de thèse a porté sur la caractérisation d’une de ces SSP (SSP1). Les résultats obtenus ont révélé des propriétés biochimiques atypiques pour cette protéine qui est capable de former une structure fibrillaire, notamment grâce à la présence d’un domaine C-terminal riche en alanine et glycine. De plus, nous avons pu montrer que cette protéine présentait une activité β-glucuronidase in vitro, qui est dépendante de son état d’oligomérisation. Une approche physiologique a également été abordée grâce à l’obtention de mutants knock-out de SSP de Podospora anserina. La caractérisation de ces mutants a montré un défaut de croissance en condition de stress oxydant et en présence de molécules perturbant l’intégrité de la paroi cellulaire. Enfin, une analyse in silico des orthologues de SSP1 a montré la présence de ce gène dans les génomes d’organismes saprophytes, ectomycorhiziens ou pathogènes suggérant un rôle indirect de cette protéine dans les processus de dégradation du bois, probablement en lien avec la gestion du stress associé / During the last decades, the enzymatic systems involved in wood degradation have been intensively studied in fungi. This has led to functional and biochemical characterization of the main extracellular enzymes that are involved in the process. However, other systems associated to the degradation mechanisms have been poorly studied. In particular, the detoxification and stress response pathways allowing the fungus to grow in and resist the toxic conditions that are associated to the degradative process are still unknown. This stress is mostly due to the presence of radicals and extractives. Extractives are putative toxic compounds produced as secondary metabolites in tree to enhance wood durability against biotic and abiotic attacks. A transcriptomic analysis performed in the laboratory highlighted the up-regulation of genes coding for small secreted proteins (SSP) in Phanerochaete chrysosporium in presence of oak extractives. The functions of these SSP are unknown in lignolytic fungi. My PhD project was focused on the characterization of one of these SSP (namely SSP1) of P. chrysosporium. The biochemical data revealed atypical features for SSP1. Indeed, it is able to form fibrilar structure, thanks to an alanine-rich and glycine-rich C-terminal domain. Moreover, we have shown that this protein exhibits β-glucuronidase activity in vitro which is dependent on its oligomerization state. Physiological data were obtained thanks to the obtention of SSP knock-out mutants in Podospora anserina. These mutants have growth defect in oxidizing stress condition and in presence of cell wall-disruptive compounds. Finally, the in silico analysis of SSP1 orthologues revealed the presence of this gene in genomes of saprophytic, ectomycorrhizal or pathogenic fungi, suggesting an indirect role of this protein in wood degradation processes, probably linked to the associated stress
35

Certificação ambiental : uma estrategia para conservação da Floresta Amazonica / Environmental certification : a strategy for the conservation of the Amazonian Forest

Maciel, Raimundo Claudio Gomes 02 January 2007 (has links)
Orientador: Bastiaan Philip Reyndon / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Economia / Made available in DSpace on 2018-08-09T14:16:14Z (GMT). No. of bitstreams: 1 Maciel_RaimundoClaudioGomes_D.pdf: 1457348 bytes, checksum: 44af1beb8683b0a3d96b7bb9bde6233f (MD5) Previous issue date: 2007 / Resumo: O processo de ocupação econômica da Amazônia tem produzido sérios problemas sociais, econômicos e ambientais. O dano mais visível é o desflorestamento que ameaça os alicerces que mantém o equilíbrio das funções sócio-econômicas e ambientais na região. Corre-se o risco de perdas irreversíveis, como da biodiversidade e do desaparecimento das populações tradicionais. As comunidades florestais estão cada vez mais marginalizadas, mesmo aquelas que moram em áreas de conservação, notadamente nas Reservas Extrativistas (RESEX). Um dos desafios do desenvolvimento sustentável na região é a viabilidade econômica dessas populações. O ponto nevrálgico para o desenvolvimento sustentável está no nível de desempenho econômico da produção de origem florestal sustentável, face aos sistemas convencionais de exploração, visto que os atributos intangíveis das explorações sustentáveis, tais como a manutenção do equilíbrio ecológico, não são capturados pelo mercado. A certificação ambiental florestal surge como um mecanismo que pode capturar, em termos monetários, os fluxos econômicos das funções ambientais da floresta, auxiliando no sustento das famílias e da conservação do meio ambiente florestal. O objetivo geral do presente trabalho é estudar a certificação ambiental como um diferencial competitivo na manutenção de vantagens competitivas sustentáveis para as comunidades extrativistas da Amazônia. O presente estudo tem como referência teórica as recentes abordagens heterodoxas sobre gestão estratégica, especialmente a perspectiva das capacitações dinâmicas, numa visão neoschumpeteriana. Ademais, discute-se um estudo de caso sobre os impactos da certificação ambiental da castanha-do-Brasil, produzida na RESEX Chico Mendes, na manutenção dos extrativistas. De acordo com os resultados encontrados, por intermédio da utilização de medidas de resultado econômico e de eficiência econômica, constata-se que a certificação ambiental em comunidades florestais gera preços justos apropriados pelos produtores florestais, justamente quando estes participam efetivamente de sua gestão e quando encontram nichos de mercados sustentáveis, corroborando a hipótese deste trabalho. Além disso, faz-se uma avaliação estratégica dos recursos e capacitações disponíveis aos extrativistas, na perspectiva de identificar os possíveis gargalos para a sustentabilidade dos resultados econômicos alcançados, além de asseverar a racionalidade econômica na utilização das florestas pelas comunidades florestais da Amazônia / Abstract: The process of economic occupation in the Amazon region has produced serious social, economic and environmental problems. The damage most visible is the deforestation that threat the foundations that the balance of the social, economic and ambient functions in the region keeps. The risk of irreversible losses is run, as of the biodiversity and the disappearance of the traditional populations. Kept out of society the forest communities are each time more, exactly those that live in conservation areas, remarkably in Extractives Reserves (RESEX). One of the challenges of the sustainable development in the region is the economic viability of these populations. The intricate point for the sustainable development is in the level of economic performance of the production of sustainable forest origin face to the conventional systems of exploration, since the intangible attributes of the sustainable explorations, such as the maintenance of the ecological balance, are not captured by the market. The forest environmental certification appears as a mechanism that can capture (in monetary terms) the economic flows of the ambient functions of the forest, assisting in the sustenance of the families and the conservation of the forest environment. The aims of this work are to study the environmental certification as a competitive differential in the maintenance of sustainable competitive advantages for the forest communities of the Amazon region. The present study it has as theoretical reference the recent heterodox approaches on strategic management, especially the perspective of the dynamic capabilities, in a neoschumpeterian vision. Argues a case study on the impacts of the environmental certification of the Brazil Nuts (produced in the RESEX Chico Mendes) in the maintenance of the forest communities. In accordance with the found results, for intermediary of the use of measures of economic result and economic efficiency, evidence that the environmental certification in forest communities generates appropriate rents for the forest producers, exactly when these participate effectively of its management and when they find niches of sustainable markets, corroborating the hypothesis of this work. Moreover, one becomes a strategic evaluation of the resources and available capabilities to the forest communities, in the perspective to identify the possible obstacles for the maintenance of the reached economic results, beyond to assert the economic rationality in the use of the forests for the forest communities in the Amazon region / Doutorado / Desenvolvimento Economico, Espaço e Meio Ambiente / Doutor em Economia Aplicada
36

Politiques fiscales et douanières en matière d'investissements étrangers en Afrique francophone : le cas du secteur des ressources naturelles extractives / Tax and customs policies on foreign investments in Francophone Africa : the case of the extractive natural resources sector

Barry, Mamoudou 27 June 2019 (has links)
Dès le début des années 1980, les États francophones d’Afrique, producteurs de matières premières, ont largement ouvert leur secteur extractif aux investissements étrangers. Cette ouverture a adopté plusieurs stratégies parmi lesquelles la fiscalité et les douanes ont occupé une place de choix. Nos travaux ont porté principalement sur ces dernières. En effet, l’enjeu de ces États a toujours été la conciliation de l’attractivité du secteur et sa rentabilité. Dans un premier temps, notre réflexion a été centrée sur les stratégies de mise en place des dispositifs fiscaux et douaniers de faveur et, dans un deuxième temps, sur la bonne gouvernance de ces dispositifs. Il ressort de nos travaux qu’au primo, si les stratégies fiscales et douanières ont réussi à attirer des investissements étrangers, la question de leur rentabilité est encore mitigée, ce pour de nombreuses raisons que nous avons analysées. C’est à ce niveau que nous avons fait des propositions d’amélioration. Au secundo, il apparaît que les conditions de la bonne gouvernance des dispositifs fiscaux et douaniers mis en place ne sont pas suffisamment réunies par les États francophones d’Afrique, d’où la nécessité de réunir ces dernières tout en améliorant les techniques de prévention et résolution des litiges. / Since the early 1980s, French-speaking African countries, producers of raw materials, have largely opened their extractive sector to foreign investments. This openness has adopted several strategies among which taxation and customs have occupied a special place. Our work focused on the latter. Indeed, the stakes of these states have always been the reconciliation of the attractiveness of the sector and its profitability. Initially, our reflection focused on the strategies for setting up favorable tax and customs systems and, secondly, on the good governance of these systems. Our research shows that, first, while tax and customs strategies have been successful in attracting foreign investments, the question of profitability is still mixed, for many reasons that we have analyzed. This is where we made suggestions for improvement. In the second, it appears that the conditions of good governance tax and customs arrangements put in place are not sufficiently met by Francophone African, hence the need reunite past and improve prevention and resolution techniques disputes.
37

Modification chimique des extractibles de bois : application à la protection du bois et des matériaux métalliques / Chemical modification of wood extractives : Application to the protection of wood and metal materials

Sahmim, Wissem 20 December 2018 (has links)
Dans ce cadre de cette thèse, nous nous intéressons à la conception, à la synthèse et à la caractérisation des propriétés physicochimiques de dérivés lipophiles d’extractibles du bois. Nous avons ainsi envisagé de modifier la structure de trois flavonoïdes dont la ressource est importante à partir de différentes essences de bois : la catéchine, le mesquitol et la naringénine pour incorporer des fonctionnalités supplémentaires. Les applications visées ici concernent principalement la protection des matériaux, en l’occurrence le bois et les métaux corrodables. En ce qui concerne la préservation du bois, il semble possible d’envisager différentes stratégies pour inhiber l’action de dégradation des champignons sur le bois. L’imprégnation des composés antioxydant tels que les polyphénols dans le bois, seuls ou en association avec un biocide pour agir en synergie, permet de limiter les effets des radicaux ou autres oxydants utilisés et générés par les pourritures, L’objectif de la modification structurale est ici d’augmenter leur hydrophobie pour limiter leur lessivage en cas d’utilisation du matériau en conditions extérieures. La deuxième application visée est la protection des matériaux métalliques. En effet, l’utilisation des produits antioxydants naturels comme inhibiteur de corrosion permet de substituer les inhibiteurs inorganiques ou les molécules organiques d’origine pétrochimique (polyamines, Imidazole…), car leur production est coûteuse et elles sont issues de ressources non renouvelables. Le greffage d’une chaîne hydrocarbonée hydrophobe sur des polyphénols ayant des propriétés antioxydantes permet d’obtenir un film protecteur sur le matériau / Within the framework of this thesis, we are interested in the design, synthesis and characterization of the physicochemical properties of lipophilic derivatives of wood extractives. We have thus considered modifying the structure of three flavonoids whose resource is important from different wood species: catechin, mesquitol and naringenin to incorporate additional functionalities. The applications reported here mainly deal with the protection of materials like wood and corrodible metals. With respect to wood preservation, it seems possible to consider different strategies to inhibit the wood degradation related to fungi on wood. Impregnation of antioxidant compounds such as lipophilic polyphenols on wood can limit the effects of radicals or other oxidants used and generated by rots. The second intended application is the protection of metallic materials. Indeed, the use of natural antioxidants as a corrosion inhibitor replace inorganic inhibitors or organic molecules (polyamines, imidazole...), because their production is expensive and toxic. The grafting of a hydrophobic hydrocarbon chain on polyphenols which have antioxidant properties allows the formation of protective films on the material
38

Le droit à l'épreuve du flux financiers illicites dans le secteur extractif : entre manipulation et double discours / Illicit financial flows within the extractive sector : between abuse and double talk

Lemaître, Sophie 11 December 2017
Le pétrole, le gaz et les minerais sont des ressources indispensables pour le bon fonctionnement de nos économies et sont très convoitées. Elles sont, en outre, particulièrement propices à l’émergence de flux financiers illicites tels que la corruption, l’évitement fiscal ou encore le blanchiment de capitaux. La prise de conscience relative à l’ampleur des pratiques illicites dans le secteur extractif est relativement récente. Depuis une vingtaine d’années, diverses mesures formant un régime juridique ambitieux ont été adoptées pour endiguer ce phénomène. Malgré l’existence de ce régime juridique, les pratiques illicites perdurent au sein de ce secteur. Les acteurs du secteur extractif, entreprises et agents publics, ont su s’adapter et faire preuve de créativité pour contourner, détourner et manipuler ce régime juridique, afin de préserver leurs avantages et de perpétuer les flux financiers illicites. Ils peuvent également recourir à l’ingénierie juridique et financière qui leur fournit un arsenal d’outils juridiques et mobilise des experts maîtrisant à la perfection l’environnement juridique, politique et financier dans lequel les acteurs du secteur extractif évoluent. Ainsi le droit peut-il être propice aux flux financiers illicites et même au service de ceux-ci tout en voulant les combattre. / Oil, gas and minerals are indispensable resources for our economies and are sought-after. They are particularly prone to illicit financial flows such as corruption, tax avoidance and money laundering. Awareness of the extent of illicit practices in the extractive sector is relatively new. Over the last two decades, various measures have been adopted, forming an ambitious legal framework to combat illicit financial flows in the extractive sector. Despite the existence of this legal framework, illicit practices are still persistent. Stakeholders within the extractive sector such as companies and public officials have been able to adapt and be creative in order to abuse, circumvent and manipulate this legal framework in order to preserve their advantages and perpetuate illicit financial flows. They can also use legal and financial engineering, which provides them with an arsenal of legal tools and mobilizes experts who master the legal, political and financial environment in which companies and public officials evolve. Hence while wanting to combat illicit financial flows, law can find itself propitious to these illicit practices and even to their service.
39

The Influence of pH, Temperature and Number of Wash Steps on the Washing Efficiency of CTMP Pulp

Monlars, André January 2021 (has links)
In this report, the washing efficiency of chemi-thermomechanical pulp (CTMP) from Norway spruce (Picea abies) was investigated when adjusting the temperature and pH during washing as well as implementing different number of wash steps. Concurrent effects of having a high pH and temperature were also examined. CTMP pulp has many uses, one of which is for the manufacturing of packaging board. Lately, this end product has seen a precipitous increase due to the increasing demand of an environmentally friendly alternative within the food packaging sector. A notorious problem associated with all mechanical pulps is how extractives are to a large extent still present after the pulping process, especially unsaturated lipids which are subject to oxidation. This results in the formation of odorous aldehydes that can be easily transferred into the food product, thus contaminating it by altering the perception of taste and odor. This is a frequent problem faced by the status quo liquid board industry. Washing is thus employed late downstream to lower the final wood resin content. Here, available literature has been collated for some basic introductory subjects such as softwood anatomy, wood resin and structures. All of this is described with a focus on softwood, leading up to a thorough breakdown of P. abies. Mechanical pulping and relevant deresination methods for CTMP production are also described, including washing. The objective of this thesis is to evaluate the trends of the final resin concentration as the chosen parameters are altered during washing. The pulp was provided by Rottneros Mill and their industrial process was simulated by using a Büchner funnel for washing. A Soxhlet extractor was used for determining the final extractive contents. It was found that the implementation of additional wash steps reduced the final resin content (1–4 wash steps). The same was found with increasing temperature (60, 70, 80 and 90 °C). The implementation of a fourth wash step seemed to be more efficient at higher temperatures. No conclusions could be drawn from altering the pH due to scattered data points with high uncertainties (pH 7, 8 and 9). The results are limited in terms of significance and are also subject to bias. / I denna rapport undersöktes tvätteffektiviteten av kemitermomekanisk massa (CTMP, chemi-thermomechanical pulp) tillverkad från gran (Picea abies) och hur den påverkas vid justeringar av temperatur, pH och antal tvättsteg. Ytterligare undersöktes förekomsten av eventuella samverkande effekter vid högre temperatur och pH. CTMP-massa har många användningsområden, däribland vid produktion av vätskekartong. På sistone har efterfrågan av vätskekartong ökat markant som ett svar på en allt större strävan efter ett mer miljövänligt alternativ inom matförpackningssektorn. Ett välkänt problem associerat med mekanisk massatillverkning är den stora mängden exktraktivämnen som kvarhålls i den färdiga massan. En viss del av dessa extraktivämnen utgörs av fleromättade fetter vilket är benägna att genomgå oxidation. Detta leder i sin tur till bildandet av flyktiga aldehyder som kan föras vidare till matprodukten och ge dem förändrad smak och lukt; ett problem som dagens vätskekartongproducenter står inför. Tillgänglig litteratur har sammanställts, där en inledande teoridel beskriver koncept såsom anatomi, strukturer och extraktivämnen hos barrved. Teoridelen övergår därefter till att ge en mer detaljerad beskrivning av P. abies och dess extraktivinnehåll. Ytterligare beskrivs mekanisk massatillverkning över lag och metoder för att eliminera extraktivämnen under produktionen av CTMP-massa (inklusive tvättning). Syftet med detta examensarbete är att utvärdera de trender i den slutliga extraktivhalten då de valda parametrarna justeras under tvättning. Massan tillhandahölls av Rottneros Bruk och deras tvättningsprocess simulerades med hjälp av en Büchner-tratt. En Soxhlet-extraktor användes för att utvärdera den slutliga extraktivhalten. Det visade sig att vid varje insättning av ett ytterligare tvättsteg (1–4 tvättsteg) gav en lägre extraktivhalt hos CTMP-massan. Desamma gällde vid ökande temperatur (60, 70, 80 and 90 °C). Implementering av ett fjärde tvättsteg tycks vara mer effektivt vid högre temperaturer. Det kunde dock inte dras några slutsatser huruvida pH påverkade tvättningen då dessa mätvärden fick stor spridning med höga osäkerheter (pH 7, 8 och 9). Resultaten besitter begränsad signifikans och kan även ha blivit utsatta för bias.
40

Resin Profile in a Bleached Kraft Pulp Process

Berglund, Jennie January 2012 (has links)
The aim with this project was to investigate how the amount and composition of resins varied during the process producing bleached birch pulp at the mill SCA Packaging Munksund. A literature study about how the resin removal can be improved has also been included. Problems with resins in the process are common at pulp and paper mills, especially when birch is used as a raw material. The resin can cause deposits on the equipment leading to process stops, but also lowered mechanical properties and spots on the paper products. The addition of tall oil to the digester is one way of improving the removal of resins, seasoning of wood, and a good debarking are other ones. Also the different washing and bleaching steps can affect the amount of resin remaining in the pulp. In this study pulp samples from eight different positions in the process were analyzed. To extract the samples a Soxtec device was used. Results showed that the most effective resin removal happened during the washing in their first washing step after the digester, a DD-washer. Here 77 % of the resin was removed, of totally 88 % during the whole process. Another step which was effective was the final washing step, the PO-press. About 36 % of the remaining resins in the pulp which entered the PO-press were washed out here. The extracts were analyzed with GC-FID and GC-MS to identify and quantify the substances, and determine how the composition varied over the manufacturing process. Twelve different compounds were identified, and the birch bark resin, betulinol, turned out to be the hardest component to remove. Over all, the sterols and triterpenols were hard to deresinate, while the removal of resin acids, fatty acids, and fatty alcohols was more effective. The PO-reactors showed a positive effect on the fragmentation of components consisting of long carbon chains and double bonds, like squalene and betulaprenols. / Målet med projektet var att utreda hur mängden och sammansättningen av hartser varierade i den blekta björkmassan under tillverkningsprocessen på pappersbruket SCA Packaging Munksund. Att göra en litteraturstudie för att ta reda på vilka metoder som kan användas för att förbättra avhartsningen var en annan del av målet. Att pappers- och massatillverkare har problem med hartser är vanligt, speciellt när björkved används som råmaterial. Hartserna kan orsaka beläggningar på utrustningen som i sin tur kan leda till processtop, men även prickar och försämrade mekaniska egenskaper hos pappersprodukten. Att tillsätta tallolja till kokaren är en vanlig metod som används för att förbättra hartsreningen, att lagra träet innan koket, och lägga fokus på att förbättra barkningen är andra metoder. Även de olika blek- och tvättstegen som används under tillverkningen av massan kan påverka hartshalten. I denna studie analyserades massaprover från åtta olika positioner i processen. En Soxtec-utrustning användes för att extrahera massaproverna. Resultatet visade att den mest effektiva avhartsningen sker under tvätten i det första tvättsteget efter kokaren, DD-filtret. Här tvättades 77 % av hartserna ut, och totalt minskade mängden hartser med 88 % under hela processen. PO-pressen var ett annat tvättsteg som var effektivt ur avhartsningssynpunkt. Här togs 36 % av den kvarvarande mängden hartser bort från massan. Extrakten som erhållits från extraktionen analyserades vidare med GC-MS och GC-FID. Dessa metoder användes för att identifiera och kvantifiera extraktivämnena, och bestämma hur sammansättningen varierade under tillverkningsprocessen. Tolv olika ämnen identifierades och den substans som visade sig vara svårast att tvätta bort var björkbark hartset, betulinol. Stort sett så var steroler och triterpenoler svårast att bli av med, medans avhartsingen av hartssyror, fettsyror och fettalkoholer var mer effektiv. Det visade sig även att PO-reaktorerna hade en sönderdelande effekt på substanser såsom squalen och betulaprenoler, dessa består av långa kolkedjor med många dubbelbindningar mellan kolatomerna.

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