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Showing 1 to 8 of 8 (0.05 seconds)Spelling suggestions: "subject:"good extractive"" "subject:"food extractive""
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A study of the fluorescence of wood and of the extractives of woodMarteny, William W. (William Wesley) 06 1900 (has links)
No description available.
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Profiling of organic extractives in wood and dissolving pulping process by chromatographic and spectroscopic methodsKilulya, Kessy Fidel 05 November 2012 (has links)
Ph.D. / The main objective of this study was to investigate the presence, variations and the fate of lipophilic extractives during all the stages in the dissolving pulp production process. Lipophilic wood extractives which include fatty acids, sterols, hydrocarbons, steroid hydrocarbons and ketones are organic compounds present in the wood and dissolving pulp which are soluble in organic solvents. Their presence in wood and pulp has negative effects on both the pulping process and the quality of the produced dissolving pulp. Comparison of two Eucalyptus species (E. grandis and E. dunnii) at three different sites (Richmond, Umvoti and Ixopo in KwaZulu-Natal Province, South Africa) revealed that lipophilic extractives were higher in E. dunnii than in E. grandis in all the sampled sites and that the woods at the Ixopo site were found to have the highest amount of lipophilic extractives. The quantitative variation of lipophilic extractives in wood was found to be significantly affected by respective sites and tree species. The principal component analysis (PCA) model, which was used to correlate soil parameters and amount of lipophilic extractives in woods per each site, revealed that high amounts of lipophilic extractives were found in trees grown at sites with a high composition of clay soil and organic matter. Thus if the industry is to avoid the high levels of lipophilic extractives in wood, sandy sites should be the choice to grow the trees. Partial least squares (PLS) modelling revealed that sterols and saturated fatty acids significantly influence the quality parameters (Kappa number, viscosity, copper number, cellulose yield and retained carbohydrates) of dissolving pulp, whereas unsaturated fatty acids and unsaturated sterols in particular were found to positively correlate with the Kappa number, thus affecting its measurement.The main objective of this study was to investigate the presence, variations and the fate of lipophilic extractives during all the stages in the dissolving pulp production process. Lipophilic wood extractives which include fatty acids, sterols, hydrocarbons, steroid hydrocarbons and ketones are organic compounds present in the wood and dissolving pulp which are soluble in organic solvents. Their presence in wood and pulp has negative effects on both the pulping process and the quality of the produced dissolving pulp. Comparison of two Eucalyptus species (E. grandis and E. dunnii) at three different sites (Richmond, Umvoti and Ixopo in KwaZulu-Natal Province, South Africa) revealed that lipophilic extractives were higher in E. dunnii than in E. grandis in all the sampled sites and that the woods at the Ixopo site were found to have the highest amount of lipophilic extractives. The quantitative variation of lipophilic extractives in wood was found to be significantly affected by respective sites and tree species. The principal component analysis (PCA) model, which was used to correlate soil parameters and amount of lipophilic extractives in woods per each site, revealed that high amounts of lipophilic extractives were found in trees grown at sites with a high composition of clay soil and organic matter. Thus if the industry is to avoid the high levels of lipophilic extractives in wood, sandy sites should be the choice to grow the trees. Partial least squares (PLS) modelling revealed that sterols and saturated fatty acids significantly influence the quality parameters (Kappa number, viscosity, copper number, cellulose yield and retained carbohydrates) of dissolving pulp, whereas unsaturated fatty acids and unsaturated sterols in particular were found to positively correlate with the Kappa number, thus affecting its measurement. Viscosity of pulp which is an important quality parameter was also found to be positively influenced by sterol residues, whereas the reducing properties of pulp were found to be affected by sterols and saturated fatty acids with a carbon chain length of less than C20.
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Coagulation and size fractionation studies on pulp and paper mill process and wastewater streamsLeiviskä, T. (Tiina) 05 January 2010 (has links)
Abstract
This thesis aims to increase our knowledge about the characteristics of chemical pulp process and wastewaters and how problematic substances, e.g. wood extractives, could be removed effectively and selectively by coagulation–flocculation with either internal or external water treatment. Characterization was performed by investigating kraft pulp bleaching filtrates, as well as wastewater, before (influent) and after (effluent) the activated sludge treatment by means of a range of chemical analyses and by carrying out size fractionation studies. Cationic polyelectrolytes were used to purify oxygen stage bleaching filtrate, and charge analyses (zeta potential, charge quantity) were carried out in order to understand the coagulation phenomenon. In activated sludge treatment, the enhancement of particle removal, either by filtration or using a chemical in the primary clarifier, would lead to savings in aeration costs and result in a more stable process. Microfiltration already with a large pore size (8 µm) removed 30–50% of the wood extractives from the influent. Separate treatment stages for certain wastewater fractions, e.g. debarking plant effluent, would ensure cost-efficiency. After the activated sludge process, the wood extractives were present as particles (18%) and < 3 kDa fraction (82%). β-sitosterol occurred only in particles in the effluent. The release of harmful components into the environment could be decreased by microfiltration (e.g. 0.45 µm) of the final effluent or using a chemical in the secondary clarifier. Interestingly a huge increase in BOD was realized in the 3 kDa fraction of both influent and effluent, which indicated the presence of toxic substances in the larger fractions. After passing the effluent into the water system, there might be a similar jump in the BOD because the effluent is diluted many-fold. This would contribute to the formation of areas with an oxygen deficit. In the coagulation–flocculation studies, effective and selective removal of wood extractives (92%) from the oxygen stage filtrate was obtained with a cationic polyelectrolyte of medium molecular weight and medium charge density at 72 °C and pH 5–6. The multimodal zeta potential distribution gave more information than the average zeta potential. Aggregation of colloidal particles occurred when only one zeta potential was observed. The number of different zeta potentials diminished with decreasing pH and after exceeding a certain polyelectrolyte dosage level.
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Measurement, nature and removal of stickies in deinked pulpSarja, T. (Tiina) 21 May 2007 (has links)
Abstract
Stickies refer to tacky contaminants in recovered paper, excluding wood extractives. Stickies originate from adhesives, ink binders and coating binders. Stickies able to pass a sieve of 100 or 150 μm (depending on standard) are called micro stickies, whereas the particles retained on the screen are called macro stickies. Dissolved and colloidal stickies are called secondary stickies. There are standard methods for macro stickies, but a standard method measuring the total amount of stickies is lacking. Furthermore, the size distribution, and nature of stickies in the sense if they are free particles or agglomerated with some other substances, has not been previously known. The information on the removal of stickies in different unit operations was also not known very well except for macro stickies. The aim of this thesis was thus to develop an analysis method for the total amount of stickies, determine the size distribution and nature of stickies, and find ways to better remove stickies in the deinking process.
Extraction with tetrahydrofuran (THF) and High Pressure Liquid Chromatography (HPLC) with Size Exclusion Column (SEC) was used here to separate hydrophobic polymers (stickies) from the pulp suspension. An Evaporating solvent Light Scattering (ELS) detector was utilized to quantify the polymers after SEC. This analysis procedure was used in this thesis to measure stickies. Fractionation of pulp before the analysis was carried out if information of different-sized stickies was desired.
The majority of stickies are micro stickies. A significant, although lower, portion of stickies are macrostickies, especially in the beginning of the deinking process. The dissolved and colloidal phase was found to contain wood extractives, and only trace amounts of stickies.
Flotation is very effective in stickies removal. Ink and micro stickies were removed nearly equally in flotation, because they both are hydrophobic and are both in an optimal size range for removal in flotation. Ink measurements may be used for estimating the trends of stickies removal in flotation. The stickies removal in flotation may be enhanced by optimizing the pulper chemistry.
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Treatments of hemi caustic and extractives streamsGandi, Ravikishor 22 May 2012 (has links)
Disposal of effluent from pulp and paper industry is one of the major problems faced by entrepreneur in view of increasing environmental standards day by day. In addition to this, industry loses economic value by disposing the effluent or selling it for a low price to other industries. Therefore, to address this problem, in the present study, 2 pulp mill effluents were selected to recover the economic value namely Hemi caustic stream and brown stock filtrate.
As far as the recovery of value of hemi caustic stream is concerned, freeze concentration technique was used to recover water in its pure form and membrane separation was used to separate hemi cellulose from effluent so that permeate can be used as a pure source of caustic elsewhere. In addition to this, hemi caustic stream was subjected to acid hydrolysis to convert hemi cellulose into sugars. These sugars can be used to produce bioethanol.
As far as the recovery of values of brown stock filtrate is concerned, it was proposed to recycle brown stock filtrate as a source of washing water for brown stock washers in the mill. However, continuous recycling of brown stock filtrate into the process causes building up of extractives in the recycle stream which in turn might deposit on the pulp and affects the quality of the pulp. Therefore, it was decided to separate extractives from the brown stock filtrate before recycle it into the mill. Dissolved Air flotation technique was used to achieve the above mentioned objective. An attempt was made to develop an improved and most reliable version of existing extractives measurement method to quantify the performance of Dissolved air flotation technique.
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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 skogsindustrinIsmailov, 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.
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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 materialsSahmim, 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
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Actions of lignocellulolytic enzymes on Abies grandis(grand fir) wood for application in biofuel productionCherdchim, Banyat 27 October 2010 (has links)
No description available.
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