L’identification de marqueurs susceptibles de mettre en évidence et quantifier l’altération du bois par différents agents de dégradation peut présenter un grand intérêt dans la mise au point de méthodes de contrôle du matériau. Dans la première partie de ce travail, la caractérisation et le dosage des composés extractibles de deux essences non durables, le hêtre et le chêne soyeux, exposées à différents champignons de pourritures blanches ou brunes préalablement traitées ou non avec du propiconazole a été effectué. L’évolution de la quantité et de la nature des extractibles dépend directement de la présence du biocide et permet de différencier clairement les éprouvettes en fonction du taux de dégradation de ces dernières. C’est le cas notamment de la catéchine présente dans les extraits de hêtre, qui disparaît rapidement lorsque le bois est exposé à un agent de pourriture et qui peut à ce titre constituer un marqueur de l’attaque du bois. Dans la seconde partie de ce travail, l’évolution de la composition chimique du bois traité par pyrolyse douce à 240°C sous azote a été étudiée. Bien que les résultats obtenus confirment en grande partie ceux décrits précédemment dans la littérature, le dosage des différentes fractions du bois (lignine et holocellulose) et l’analyse des monosaccharides constitutifs de la fraction holocellulose du bois ont permis de mettre en évidence un important phénomène de carbonisation rapporté jusqu’à présent pour des températures plus élevées. Ce phénomène confirmé par RMN13C peut être à l’origine de certaines des nouvelles propriétés du matériau. / The identification of markers able to highlight and quantify wood deterioration by different degradation agents can be of great interest in the development of material control methods. In the first part of this work, the characterization and the quantification of the two non durable wood species extractives, beech and silky oak, treated or not with propiconazole and exposed to various white rot or brown rot fungi were carried out. The evolution of the quantity and the nature of extractives depend directly on the presence of biocide and allowed to clearly differentiate degraded and non-degraded samples. This is particularly true in the case of catechin identified in the extracts of beech, which is rapidly degraded by rotting fungi constituting therefore a valuable marker of wood degradation. In the second part of this work, the evolution of the chemical composition of wood treated by mild pyrolysis at 240°C under nitrogen was investigated. Although the results mainly confirm those described previously in the literature, isolation of lignin and holocellulose fractions and analysis of monosaccharides constitutive of holocellulose fraction highlighted an important carbonization of wood reported up to now for higher temperatures. This phenomenon is confirmed by 13C NMR and could be at the origin of some of the new properties of the material.

With a growing population but scarce primary phosphorus sources, recycling of the vital element has become an important research area throughout the last decades. Several streams in society are potential resources for recirculation but municipal sewage is considered one of the most available materials. With current technologies in wastewater treatment, over 95 % of the influent phosphorus is captured in the sludge along with a variety of other nutrients. However, due to increasing fractions of pharmaceutical residues and heavy metals also following the sludge, direct use as fertiliser is being phased out in most European countries in favour of extraction methods. Extraction of nutrients from the sludge is problematic mainly because of dewaterability difficulties. Thus, pretreatment of the material is required to access the desired components at a reasonable cost and energy consumption. Hydrothermal carbonisation (HTC) is a technology showing high potential for treatment of wet carbonaceous material without necessity of prior drying. The resulting product is hygenised, essentially free from pharmaceuticals and easily dewatered. In this Master’s thesis principal conditions for release of phosphorus from HTC converted digested sludge under acid leaching have been experimentally investigated. Dependence of time, temperature, dry solids (DS) content of HTC sludge and pH have been studied. Also, differences arising from acid type have been considered by comparing acidulation with sulphuric acid and hydrochloric acid. A short investigation of the recovery of the dissolved phosphorus from leachate by precipitation was also performed where calcium ions were added to both sulphuric and hydrochloric acid leachates. Extraction of phosphorus from HTC converted sludge has shown to be easier than from pure metal phosphates under comparable leaching conditions and pH values. Also, the dissolved phosphorus concentrations obtained in the presence of HTC converted sludge was higher than for theoretical equilibrium concentrations where all phosphorus is in the form of iron(III) or aluminium(III) phosphate. A maximum leachate phosphorus concentration was around 2500 mg/L, recorded in leaching experiments performed at a dry HTC product concentration of 10 % (w/w) in an extraction solution of water acidified with sulphuric acid. Leaching procedures performed at pH values between 2 and 1 with 1 and 5 % DS HTC product resulted in dissolution of 90 % of ingoing phosphorus at an acid charge of 0.5 kg H2SO4/kg DS HTC product. At this chemical charge, release of phosphorus from converted sludge is fast. Similar amounts of dissolved phosphorus were recorded after 15 min as after 16 h retention time. Possibly, time dependence becomes relevant at lower charges. The dissolution of phosphorus is negatively affected by temperature increases at moderate acid loads, and by possibly by hydrochloric acid at pH values below 2. Addition of calcium gave a dissolved phosphorus reduction of 99.9 % in both the sulphuric acid and hydrochloric acid leachates. Gypsum, CaSO4, also precipitates from the sulphuric acid leachate resulting in 67 % more dry mass. Due to high release of metals during acidulation, the precipitate was also contaminated with large fractions of metals in addition to calcium. In summary, this investigation has demonstrated that up to 90 % of the phosphorus content of the HTC converted sludge can be released by acid leaching, and almost 100 % of the phosphorus can be recovered from the leachate by precipitation with calcium ions.

Nanoporous carbon materials are widely used in industry as adsorbents or catalyst supports, whilst becoming increasingly critical to the developing fields of energy storage / generation or separation technologies. In this thesis, the combined use of carbohydrate hydrothermal carbonisation (HTC) and templating strategies is demonstrated as an efficient route to nanostructured carbonaceous materials. HTC is an aqueous-phase, low-temperature (e.g. 130 – 200 °C) carbonisation, which proceeds via dehydration / poly-condensation of carbon precursors (e.g. carbohydrates and their derivatives), allowing facile access to highly functional carbonaceous materials. Whilst possessing utile, modifiable surface functional groups (e.g. -OH and -C=O-containing moieties), materials synthesised via HTC typically present limited accessible surface area or pore volume. Therefore, this thesis focuses on the development of fabrication routes to HTC materials which present enhanced textural properties and well-defined porosity. In the first discussed synthesis, a combined hard templating / HTC route was investigated using a range of sacrificial inorganic templates (e.g. mesoporous silica beads and macroporous alumina membranes (AAO)). Via pore impregnation of mesoporous silica beads with a biomass-derived carbon source (e.g. 2-furaldehyde) and subsequent HTC at 180 oC, an inorganic / carbonaceous hybrid material was produced. Removal of the template component by acid etching revealed the replication of the silica into mesoporous carbonaceous spheres (particle size ~ 5 μm), representing the inverse morphological structure of the original inorganic body. Surface analysis (e.g. FTIR) indicated a material decorated with hydrophilic (oxygenated) functional groups. Further thermal treatment at increasingly elevated temperatures (e.g. at 350, 550, 750 oC) under inert atmosphere allowed manipulation of functionalities from polar hydrophilic to increasingly non-polar / hydrophobic structural motifs (e.g. extension of the aromatic / pseudo-graphitic nature), thus demonstrating a process capable of simultaneous control of nanostructure and surface / bulk chemistry. As an extension of this approach, carbonaceous tubular nanostructures with controlled surface functionality were synthesised by the nanocasting of uniform, linear macropores of an AAO template (~ 200 nm). In this example, material porosity could be controlled, showing increasingly microporous tube wall features as post carbonisation temperature increased. Additionally, by taking advantage of modifiable surface groups, the introduction of useful polymeric moieties (i.e. grafting of thermoresponsive poly(N-isopropylacrylamide)) was also demonstrated, potentially enabling application of these interesting tubular structures in the fields of biotechnology (e.g. enzyme immobilization) and medicine (e.g. as drug micro-containers). Complimentary to these hard templating routes, a combined HTC / soft templating route for the direct synthesis of ordered porous carbonaceous materials was also developed. After selection of structural directing agents and optimisation of synthesis composition, the F127 triblock copolymer (i.e. ethylene oxide (EO)106 propylene oxide (PO)70 ethylene oxide (EO)106) / D-Fructose system was extensively studied. D-Fructose was found to be a useful carbon precursor as the HTC process could be performed at 130 oC, thus allowing access to stable micellular phase. Thermolytic template removal from the synthesised ordered copolymer / carbon composite yielded functional cuboctahedron single crystalline-like particles (~ 5 μm) with well ordered pore structure of a near perfect cubic Im3m symmetry. N2 sorption analysis revealed a predominantly microporous carbonaceous material (i.e. Type I isotherm, SBET = 257 m2g-1, 79 % microporosity) possessing a pore size of ca. 0.9 nm. The addition of a simple pore swelling additive (e.g. trimethylbenzene (TMB)) to this system was found to direct pore size into the mesopore size domain (i.e. Type IV isotherm, SBET = 116 m2g-1, 60 % mesoporosity) generating pore size of ca. 4 nm. It is proposed that in both cases as HTC proceeds to generate a polyfuran-like network, the organised block copolymer micellular phase is essentially “templated”, either via hydrogen bonding between hydrophilic poly(EO) moiety and the carbohydrate or via hydrophobic interaction between hydrophobic poly(PO) moiety and forming polyfuran-like network, whilst the additive TMB presumably interact with poly(PO) moieties, thus swelling the hydrophobic region expanding the micelle template size further into the mesopore range. / Nanoporöse kohlenstoffbasierte Materialien sind in der Industrie als Adsorbentien und Katalysatorträger weit verbreitet und gewinnen im aufstrebenden Bereich der Energiespeicherung/erzeugung und für Trennverfahren an wachsender Bedeutung. In der vorliegenden Arbeit wird gezeigt, dass die Kombination aus hydrothermaler Karbonisierung von Zuckern (HTC) mit Templatierungsstrategien einen effizienten Weg zu nanostrukturierten kohlenstoffbasierten Materialien darstellt. HTC ist ein in Wasser und bei niedrigen Temperaturen (130 - 200 °C) durchgeführter Karbonisierungsprozess, bei dem Zucker und deren Derivate einen einfachen Zugang zu hochfunktionalisierten Materialien erlauben. Obwohl diese sauerstoffhaltige Funktionalitäten auf der Oberfläche besitzen, an welche andere chemische Gruppen gebunden werden könnten, was die Verwendung für Trennverfahren und in der verzögerten Wirkstofffreisetzung ermöglichen sollte, ist die mittels HTC hergestellte Kohle für solche Anwendungen nicht porös genug. Das Ziel dieser Arbeit ist es daher, Methoden zu entwickeln, um wohldefinierte Poren in solchen Materialien zu erzeugen. Hierbei führte unter anderem der Einsatz von anorganischen formgebenden mesoporösen Silikapartikeln und makroporösen Aluminiumoxid-Membranen zum Erfolg. Durch Zugabe einer Kohlenstoffquelle (z. B. 2-Furfural), HTC und anschließender Entfernung des Templats konnten poröse kohlenstoffbasierte Partikel und röhrenförmige Nanostrukturen hergestellt werden. Gleichzeitig konnte durch eine zusätzliche Nachbehandlung bei hoher Temperatur (350-750 °C) auch noch die Oberflächenfunktionalität hin zu aromatischen Systemen verschoben werden. Analog zur Formgebung durch anorganische Template konnte mit sog. Soft-Templaten, z. B. PEO-PPO-PEO Blockcopolymeren, eine funktionelle poröse Struktur induziert werden. Hierbei machte man sich die Ausbildung geordneter Mizellen mit der Kohlenstoffquelle D-Fructose zu Nutze. Das erhaltene Material wies hochgeordnete Mikroporen mit einem Durchmesser von ca. 0,9 nm auf. Dieser konnte desweiteren durch Zugabe von Quell-Additiven (z. B. Trimethylbenzol) auf 4 nm in den mesoporösen Bereich vergrößert werden. Zusammenfassend lässt sich sagen, dass beide untersuchten Synthesewege nanostrukturierte kohlenstoffbasierte Materialien mit vielfältiger Oberflächenchemie liefern, und das mittels einer bei relativ niedriger Temperatur in Wasser ablaufenden Reaktion und einer billigen, nachhaltigen Kohlenstoffquelle. Die so hergestellten Produkte eröffnen vielseitige Anwendungsmöglichkeiten, z. B. zur Molekültrennung in der Flüssigchromatographie, in der Energiespeicherung als Anodenmaterial in Li-Ionen Akkus oder Superkondensatoren, oder als Trägermaterial für die gezielte Pharmakotherapie.

Les charbons de bois trouvés en contexte archéologique permettent de reconstituer les couverts forestiers passés et les pratiques sylvicoles associées. Le δ13C de ces charbons a été utilisé pour des reconstructions paléoclimatiques, cependant ses variations peuvent aussi être dues à la carbonisation. Afin de mieux contraindre, à l’échelle du cerne, les variations du δ13C du bois dues à la carbonisation, des carbonisations ont été faites avec des échantillons de chêne cadicufoliés en conditions proches des foyers domestiques. Une diminution du δ13C après la carbonisation a été observée. Cet effet est très variable, notamment en fonction du compartiment du bois considéré (aubier, duramen, bois initial, bois final). Ces mesures de δ13C ont été complétées par celles du taux de carbone montrant qu’il ne varie pas parallèlement au δ13C. De ce fait l’utilisation, prônée par certains travaux, du taux de carbone pour évaluer les variations de d13C suite à la carbonisation n’est pas pertinente. Cependant, les variations cerne à cerne et intracerne du δ13C ne sont pas significativement affectées par la carbonisation, et des reconstructions climatiques à partir du δ13C de bois carbonisés paraissent donc envisageables. Afin de tester cette approche cerne à cerne, plusieurs charbons archéologiques issus du site Néolithique de Chalain, dont les paléoclimats étaient bien documentés, ont été échantillonnés. Cette approche a été couplée à des mesures dendro-anthracologiques (largeurs des cernes, proportion du bois final, rayon de courbure et proportion de vaisseaux avec des thylles) afin de mieux comprendre les variations de δ13C mesurées, et de tenter de les coupler aux pratiques sylvicoles. Les valeurs de δ13C sont en accord avec les paléoclimats déjà inférés et les variations intra-cerne, ou saisonnières, de δ13C révèlent que la période froide était caractérisée par des saisons plus contrastées. Les mesures dendro-anthracologiques ont permis, entre autres, de préciser les variations de δ13C entre les différents compartiments du bois et de proposer une interprétation concernant les variations des pratiques sylvicoles en lien avec le climat. En conclusion, la carbonisation oxygénée provoque un abaissement des valeurs de δ13C du bois mais n’empêche pas les reconstructions paléo-climatiques à partir de leurs variations, notamment saisonnières, mesurées sur des charbons archéologiques. / Archeological charcoals are used for reconstructing past woodland vegetation and the related historical forest practices. Charcoals δ13C are used for paleoclimate reconstructions. To better constrain the use of δ13C, we investigated the effect of oxygenated carbonization on ring scale δ13C variations in oak wood. Results showed a significant decrease of δ13C values after carbonization. This effect, however, is highly variable according to the wood compartment considered: heartwood, sapwood, earlywood, or latewood. Carbon content measurements do not exhibit the same variations along oxygenated carbonization as observed with δ13C. Therefore, the use of carbon content for evaluating carbonization effects on δ13C, which is proposed by some authors, is not appropriate. Interannual and seasonal δ13C variations, however, are not significantly affected by oxygenated carbonization. Thus, paleoclimate reconstruction from charcoals δ13C appears possible. To test both ring scale variations, archeological charcoals were sampled from a climatically well documented Neolithic site of Chalain. Several dendro-anthracological parameters (latewood proportion, duraminization, charcoal-pith distance estimation) were characterized for a better understanding of δ13C variations, in order to integrate historical woodland practices and the climatic interpretations. Charcoal tree-rings exhibited width and δ13C significantly different between the two studied periods, in agreement with previously inferred climatic difference. Intra-ring δ13C suggested that the cool and moist climatic period also corresponded to higher seasonal contrast than the dryer climatic period. Dendro-anthracological parameters allow better understanding of δ13C variations between wood compartments and provide information on past woodland exploitations. To conclude, oxygenated carbonizations induce a decrease in wood δ13C values, but do not prevent the paleoclimate interpretations of δ13C variations in archeological charcoals.

Fire presents a great risk to humans and their possessions. Polymeric compounds are highly flammable and compounds are added to increase their fire resistance. These additives are referred to as flame retardants. Intumescent flame retardants are systems that form a carbon rich foam on the surface of the polymer during thermal degradation. A new field of metal catalysed intumescence is discussed in this document. The influence of both the metal ion and organic backbone of polyhydroxylcarboxylic acid metal salts was studied. The intumescence and foaming properties of selected salts were studied in more detail. Gluconic acid proved to be the best intumescent and showed the best combination of carbon char yield, foam structure and volume, stability and open flame characteristics. As a general rule of thumb, the char volume and structure improved with an increased number of hydroxyl groups in the compound. Carbon char yield increased with an increase in the number of hydroxyl groups for a constant number of carbons in the complex. The number of acid groups in the compound played a lesser role in intumescence. Most metal complexes catalyse intumescent decomposition of polyhydric compounds such as polyhydroxylcarboxylic acids and pentaerythritol. The reduction in the volatilisation losses implies that the metal cations catalyse carbonisation reactions in the polyhydroxyl compound. Unfortunately, the resultant carbon-foams are unstable: the metal residues also catalyse the further oxidative degradation of the char. The low thermal stability of the compositions tested, as well as the afterglow effect makes them unsuitable for use as flame retardant additives in plastics. From the studies of the different metal complexes with acetylacetone and gluconic acid, it was concluded that the calcium ion exhibited the most promise. When pyrolysed in air with an open gas flame or in a furnace, calcium gluconate monohydrate produces voluminous foam. The foam is of a closed cell structure, densely packed and has no mechanical strength. The cell walls are very thin (5 to 50 nm) and the cells are between 50 µm and 200 µm in size. If the sample is compressed before heating, the resultant foam produced during pyrolysis is less voluminous than that of the loose powder. The BET surface area of the calcium gluconate monohydrate foamed at 300°C for 5 min. is 16.0 m2/g. The foam produced after 5 min heating at 300°C has a thermal conductivity similar to standard polystyrene foam. Adding leached silica to the calcium gluconate monohydrate increases mechanical strength of the foam, but influences the foam volume negatively. The optimum silica level was calculated to be 1:1 gluconate to silica on a mole ratio (11.8% SiO2 by mass). The mechanical strength of the foam can also be increased with the addition of expandable graphite. The graphite has a lesser influence on the foam volume than the silica, but also reduces the foam volume. However, the addition of the expandable graphite gives the sample more .opening. force, as the foam volume of a compressed sample pyrolysed, is similar to that of the heated loose powder. Calcium gluconate monohydrate starts to degrade at 120°C, losing its crystal water and shows a mass loss of 4% at 180°C. The exothermic peak (shown in the DSC/TGA data) associated with the metal catalysed carbon oxidation (afterglow) is observed at 570°C in air. For the calcium gluconate monohydrate the transition from CaCO3 to CaO occurs above 650°C in air. It has been shown that the foaming of polyhydroxylcarboxylic acids is due to the formation of water vapour during degradation. For calcium gluconate monohydrate, foaming starts due to the loss of crystal water and is continued by the loss of hydroxyl groups as water. The bulk of the foaming is due to the second reaction. It has been shown that compounds with crystal waters produce a more voluminous and lower density foam. The foam is an amorphous carbon rich residue. The molecular mass of the carbon residue increases up to a heating temperature of 300°C. This implies that the carbon residue crosslinks during formation, forming a stretchable cell wall for the foam. Compounds with a .free. hydroxyl group at the end of the carbon chain produce a foam of larger volume and lower density. This supports the crosslinking theory. The foam produced when calcium gluconate monohydrate is heated for 5 min at 300°C in air is of very low density . 2.5 kg/m3 based on residual mass. The density of the calcium gluconate monohydrate pyrolysed at 1000°C for 5 min in air yields a CaO with a density of 20 kg/m3 . This implies that the high temperature pyrolysis of calcium gluconate can produce an inorganic oxide of low bulk density and possible high specific surface area. The BET surface area of CaCO3 from the gluconate pyrolysed at 600°C is ~ 12 m2 /g. An intumescent coating containing calcium gluconate monohydrate, leached silica and expandable graphite as a system was prepared and compared to commercial formulations. This gluconate based system was at least as efficient as the commercial formulations when painted on balsa wood planks or aluminium plates. On cardboard sheets it did not perform as well as the commercial systems. More work should be done to overcome the afterglow effect observed with metal- based intumescent systems. The crystal structure of calcium gluconate monohydrate should be determined as to understand the decomposition better. It is unclear whether the decomposition is catalysed inter- or intramolecularly. / Thesis (PhD(Chemical Engineering))--University of Pretoria, 2005. / Chemical Engineering / unrestricted

Hydrothermal carbonisation (HTC) could form the basis for rendering human faecal wastes safe whilst at the same time generating a carbon-rich material (hydrochar) and providing prospects for the recovery of energy. The work presented here has an objective of the search for optimal conditions for the HTC conversion of human faecal waste. Primary sewage sludge (PSS) and synthetic faeces (SF), of various moisture contents, were used as feedstocks to investigate the kinetics of decomposition of solids during HTC over a range of reaction times and temperatures. Decomposition was found to follow first-order kinetics, and the corresponding activation energies were obtained. Temperature was of primary importance to influence solid decomposition. Higher temperatures resulted in higher solids conversion to hydrochar. The energy contents of the hydrochars from PSS carbonised at 140 200oC for 4 h ranged from 21.5 to 23.1 MJ kg 1. Moisture content was found to affect the HTC process and feedstocks, with higher initial moisture contents resulted in lower hydrochar yields. The effect of reaction conditions on the characteristics of the hydrochar, liquid and gas products from HTC of faecal material, and the conditions leading to optimal hydrochar characteristics were investigated using a Response Surface Methodology (RSM). Models were developed here which could aid in the identification of reaction conditions to tailor such products for specific end uses. The results showed that the amount of carbon retained in hydrochars decreased as temperature and time increased, with carbon retentions of 64 77% at 140 and 160oC, and 50 62% at 180 and 200oC. Increasing temperature and reaction time increased the energy content of the hydrochar from 17 19 MJ kg 1 but reduced its energy yield from 88 to 68%. HTC at 200oC for 240 min resulted in hydrochars suitable for fuel, while carbonation at 160oC for 60 min produced hydrochars appropriate for carbon storage when applied to the soil. Theoretical estimates of methane yields resulting from subsequent anaerobic digestion (AD) of the liquid by-products are presented, with the highest yields obtained following carbonisation at 180oC for 30 min. In general, HTC at 180oC for 60 min and 200oC for 30 min resulted in hydrochars having optimal characteristics, and also for obtaining optimal methane yields. Maillard reaction products were identified in the liquid fractions following carbonisations at the higher temperatures. It was also found that the TOC, COD and BOD of the liquid products following HTC increased as the reaction temperature and time were increased and that these would require further treatment before being discharged. The results indicated that the gaseous phase following HTC contained carbon dioxide, nitrogen dioxide, nitric oxide, ammonia, and hydrogen sulphide indicating that additional treatment would be required before discharge to the atmosphere. In order to identify the optimum conditions leading to greater filterability of slurry resulted from HTC, the effects of reaction temperature and time on the filterability of PSS and SF slurries were investigated and optimised using RSM. It was shown that filterability improved as the reaction temperature and time at which the solids were carbonised was increased, with the best filtration results being achieved at the highest temperature (200°C) and longest treatment time (240 min) employed here. The specific cake resistance to filtration of the carbonised slurries was found to vary between 5.43 x 1012 and 2.05 x 1010 m kg 1 for cold filtration of PSS, 1.11 x 1012 and 3.49 x 1010 m kg 1 for cold filtration of SF, and 3.01 x 1012 and 3.86 x 1010 m kg 1 for hot filtration of SF, and decreased with increasing reaction temperature and time for carbonisation. There was no significant difference in specific resistance between cold and hot filtration of SF. The RSM models employed here were found to yield predictions that were close to the experimental results obtained, and should prove useful in designing and optimising HTC filtration systems for generating solids for a wide variety of end uses. Mass and energy balances of a semi-continuous HTC of faecal waste at 200oC and a reaction time of 30 min were conducted and based on recovering steam from the process as well energy from the solid fuel (hydrochar) and methane from digestion of the liquid by-product. The effect of the feedstock solids content and the quantity of feed on the mass and energy balances were investigated. Preheating the feed to 100oC using heat recovered from the process was found to significantly reduce the energy input to the reactor by about 59%, and decreased the heat loss from the reactor by between 50 60%. For feedstocks containing 15 25% solids (for all feed rates), energy recycled from the flashing off of steam and combustion of the hydrochar would be sufficient for preheating the feed, operating the reactor and drying the wet hydrochar without the need for any external sources of energy. Alternatively, for a feedstock containing 25% solids for all feed rates, energy recycled for the flashing off of steam and combustion of the methane provides sufficient energy to operate the entire process with an excess energy of about 19 21%, which could be used for other purposes.

Ce mémoire traite de la carbonisation de différents déchets de biomasse par pyrolyse douce dans une première étape. Dans une seconde étape, les charbons produits ont été activés à la vapeur d'eau. Six essences de bois (charme, chêne, douglas, épicéa de Sitka, hêtre et peuplier) ont été carbonisées et l'activation a été étudiée sur 4 essences (chêne, douglas, épicéa et peuplier). La première partie de ce mémoire consiste en une étude bibliographique sur la biomasse et sa valorisation énergétique, la production de charbons et l'activation. La deuxième partie de ce rapport présente les résultats expérimentaux relatifs à la carbonisation. Lorsque la carbonisation est complète, on peut corréler les principales propriétés physiques des charbons produits à partir des propriétés initiales du bois anhydre. Les modifications anatomiques induites par la carbonisation ont été expliquées à partir de mesures sur un porosimètre à mercure et d'observations au microscope électronique. Dans la troisième partie, les charbons obtenus à partir des 4 essences citées ont été activés à la vapeur d'eau à 800 °C pendant une heure. Les principales propriétés physiques caractérisant les charbons activés ont été déterminées. L'adsorption du phénol en phase aqueuse a été étudiée et les isothermes de sorption à 25 °C ont été décrites. L'étude des transferts de matière a montré que l'adsorption du phénol pouvait être caractérisée par un coefficient global de transfert de matière. Pendant l'adsorption, trois étapes limitantes successives ont été observées pendant lesquelles le coefficient global de transfert de matière est assez constant et dont la valeur est divisée par un facteur 10 à chaque changement d'étape / This report concerns the carbonization of different biomass wastes by soft pyrolysis in a first part. In a second part, the charcoals produced have been activated by water vapor. 6 wood species (ash, oak, douglas, Sitka spruce, beech and poplar) have been carbonized and the activation has been investigated on 4 wood species (oak, douglas, spruce and poplar). The first chapter of this report consists in a bibliographical study on biomass, its energetic valorization, production of charcoals and their activation. The second chapter of this report presents the experimental results concerning the carbonization. When the carbonization is complete, the main physical properties of the charcoals produced can be correlated to the initial properties of oven dry woods. The anatomic changes induced by pyrolysis have been explained from measurements performed on a mercury porosimeter and observations on an electronic microscope. In the third chapter, charcoals produced from the 4 wood species cited have been activated with water vapor at 800 °C during 1 hour. The main physical parameters characterizing the activated carbons have been determined. The adsorption of phenol in an aqueous phase has been investigated and the isotherms of sorption at 25 °C have been described. The study of mass transfers shows that the adsorption of phenol can be characterized by a global mass transfer coefficient. During the adsorption, 3 successive limiting steps have been observed. For each step, the mass transfer coefficient is quite constant but its value is divided by about 10 after each change of step

Cette thèse est focalisée sur la contribution de l'étude couplée de l’organisation multi-échelle et de la composition isotopique de C et N des carbones de météorites différenciées (acapulcoites – lodranites (A-L)), pour mieux comprendre l’histoire de leur corps-parent. Nous avons systématiquement combiné observations des carbones de ces météorites avec des analogues expérimentaux. Nous avons développé une méthodologie originale couplant l'étude de l'organisation des échelles micrométriques à nanométriques (par Microscopie Electronique par Transmission et Microspectrométrie Raman) et l'analyse isotopique des carbones (par SIMS) sur rigoureusement les mêmes plages de dimensions micrométriques. La comparaison avec les mélanges expérimentaux indique que le graphite d’Acapulco s’est formé par un mode de graphitisation "catalysée par le fer". L’absence de graphitisation des carbones de Lodran dans un environnement riche en fer et chaud est apparemment paradoxale. Toutes nos observations peuvent être réconciliées si nous considérons une collision tardive du corps-parent des A-L avec un corps chondritique apportant matière organique insoluble et chaleur d'impact. Ce scénario est conforté par les analyses isotopiques qui indiquent une formation des carbones des A-L par carbonisation d’un précurseur chondritique et une migration d’effluents carbonés au sein du corps-parent / This thesis is focused on the contribution of the coupling of multi-scale organization and C, N isotopic composition of carbons in differentiated meteorites (acapulcoites – lodranites (A-L)), in order to better understand the history of their parent body. We systematically combined observations of carbons from these meteorites with experimental analogues. We developed an original methodology associating the study of the organization at the micrometre to nanometre scales (by Transmission Electron Microscopy and by Raman Microspectrometry), and the analysis of the isotopic composition of carbons (by SIMS) on strictly the same areas of micrometre dimensions. The comparison with experimental analogues indicates that the Acapulco graphite was formed by a "catalytic" graphitization mode. The absence of graphite in Lodran, in an iron-rich and hot environment, is apparently paradoxical. All our observations can be reconciled if we consider a late collision of the A-L parent body with a chondritic body bringing insoluble organic matter and impact heat. This scenario is strengthened by isotopic analyses, which indicate formation of A-L carbons by carbonization of a chondritic precursor and migration of carbonaceous effluents within the parent-body

Cette thèse est focalisée sur la contribution de l'étude couplée de l'organisation multi-échelle et de la composition isotopique de C et N des carbones de météorites différenciées (acapulcoites - lodranites (A-L)), pour mieux comprendre l'histoire de leur corps-parent. Nous avons systématiquement combiné observations des carbones de ces météorites avec des analogues expérimentaux. Nous avons développé une méthodologie originale couplant l'étude de l'organisation des échelles micrométriques à nanométriques (par Microscopie Electronique par Transmission et Microspectrométrie Raman) et l'analyse isotopique des carbones (par SIMS) sur rigoureusement les mêmes plages de dimensions micrométriques. La comparaison avec les mélanges expérimentaux indique que le graphite d'Acapulco s'est formé par un mode de graphitisation "catalysée par le fer". L'absence de graphitisation des carbones de Lodran dans un environnement riche en fer et chaud est apparemment paradoxale. Toutes nos observations peuvent être réconciliées si nous considérons une collision tardive du corps-parent des A-L avec un corps chondritique apportant matière organique insoluble et chaleur d'impact. Ce scénario est conforté par les analyses isotopiques qui indiquent une formation des carbones des A-L par carbonisation d'un précurseur chondritique et une migration d'effluents carbonés au sein du corps-parent

La carbonisation hydrothermale (HTC) est un procédé de conversion en énergie de la biomasse dans l’eau sous critique (180-250°C) à faibles pressions (10-40 bars). Ce procédé conduit à la production d’un matériau solide carboné appelé "hydro-char". L’objectif de ce travail est d’optimiser le procédé HTC par l’étude des performances de l’hydro-char comme source d’énergie. La biomasse étudiée est un résidu d’extraction d’huile d’olive dénommé grignons d’olive constitués de peau, de pulpe et de noyau (taux d’humidité de 70%). Ces grignons d’origine marocaine ont été préalablement séchés (GOS). Au cours de l’HTC, la biomasse est décomposée via des réactions de déshydratation et de décarboxylation. Les hydro-chars sont moins humides et plus riches en carbone que les GOS. Aussi, ils s’appauvrissent en cendres en les transférant dans la phase liquide. Les hydro-chars ont un PCS plus élevé que celui de la tourbe et de lignite. Les résultats montrent que le rendement et les propriétés de l’hydro-char dépendent surtout de la température du procédé. Pour mieux analyser l’effet des conditions opératoires, l’approche des plans d’expériences a été appliquée pour optimiser et modéliser le procédé HTC. Grâce au plan de Doehlert, on peut relier les propriétés de l’hydro-char avec son rendement massique et son comportement thermique de combustion. La représentation des surfaces de réponses a permis de définir les zones de production d’hydro-char avec ses propriétés permettant d’orienter l’élaboration de l’hydro-char pour répondre aux critères d’une application prédéfinie. Le liquide issu de l’HTC des GOS montre une sensibilité à la variation des conditions opératoires. Le carbone soluble dans ce liquide lui donne un pouvoir polluant. Pour le diminuer, deux procédés de traitement ont été testés: l’évaporation et l’oxydation en voie humide. Les résultats ont montré que la quantité d’eau utilisée pour le traitement est le facteur le plus influent sur le bilan énergétique du procédé HTC. / Hydrothermal carbonization (HTC) allows pre-treating humid biomass in subcritical water (180-250°C) and at low pressures (10-40 bars) in the absence of air. This process produces a carbonaceous solid material called "hydro-char". The main aim of this work is to optimize the HTC process by studying the potential of hydro-char to produce energy. The studied biomass is a by-product of the olive oil industry called olive pomace containing water, residual oil, olive skin, olive pulp, and olive stones (with 70% moisture content). The moroccan olive pomace was first air-dried (DOP) and characterized. During the HTC process, the biomass is decomposed via dehydration and decarboxylation reactions. The obtained hydro-char has much less moisture and higher carbon contents than that of untreated DOP. Also, the hydro-char becomes poor in ashes by transferring them into the liquid phase. Hydro-chars have a higher HHV than that of peat and lignite. The results show that hydro-char mass yield and its properties depend on the process temperature especially. For a better analysis of the effect of operating conditions, a Design of Experiments Response Surface Methodology (DoE/RSM) approach was applied to optimize the HTC process. The DoE/RSM allows identifying a relationship between hydro-char properties and its mass yield and thermal combustion behavior. Response-surface plots show defined areas of production of hydro-char which allows tailoring hydro-char elaboration to a specific application. The process liquid from the HTC treatment of DOP shows a sensibility to operating conditions. The soluble carbon in the HTC liquid increases its polluting power and to decrease it two treatment process have been tested: evaporation and wet oxidation. Finally, the results show that the amount of water used for the hydrothermal treatment is the most influential factor on the energy balance of the HTC process.