This work is dealing with the utilization of biomass feed stocks and wooden residue for gasification process to produce syn-gas suitable for the implementation of power plants for electricity generation and problem of gas production suitable for further chemical and energy purpose discussing the suitable practical purification methods, given that the complexity of theme and project which carried out through detailed analysis. Since the obtained gas has many types of unwanted contaminants. It was necessary to derive an effective cleaning method for gas purification from chemical contaminants especially tars components. The discussion of the definitions and methods for the determination of gas unwanted components and their removal technologies on the basis of the knowledge of data, collecting and analysis carried out through an experimental massive approach. The theoretical analysis of the gasification process for an effective tar reduction in the produced gas has been studied as well. Since the quality requirements for internal combustion engines, gas turbines and fuel cells using the primary measurement methods cannot be achieved for gas production, this work aimed removing different particulates and tar. The main emphasis is placed on the methods of high cleaning taking in account the chemical and thermal specifications of the gas which is based on the utilization of three different kinds of carbon materials successfully and efficiently char coal, black coke and active carbon for tar removal which has a major impact on the process parameters. The analysis was responding with the mechanism and the techniques of minimizing the resultant allowable concentration by using a suitable materials and verifying the operation conditions without affecting the gas thermal efficiency. The highlights of the theoretical and experimental work has been drawn up by a high concept cleaning allowing the production of a pure gas having a quality that meets the modern technical requirements for electricity generation. Functionality the most efficient cleaning methods were based in the current project for tar reduction on the quantity of tar removed, the materials used for tar cracking and the conditions of the experimental work as well. For a successful application, some proposals have been settled for industrial applications of gas cleaning.

No description available.

No description available.

Yes / Boron dipyrromethene derivates (BODIPYs) are promising photosensitisers (PSs) for cancer treatment using photodynamic therapy (PDT). This study investigates the functionalisation of graphene oxide (GO) with a BODIPY derivate for glutathione (GSH) depletion and PDT. The functionalisation of GO with a 3,5-dichloro-8-(4-boronophenyl) BODIPY via a diol derivatisation with the phenyl boronic acid moiety at the meso position of the BODIPY core, allowed to preserve the intrinsic properties of GO. We demonstrated that both chlorine atoms were substituted by GSH in the presence of glutathione transferase (GST), inducing a relevant bathochromic shift in the absorption/emission features and thus generating the active PS. Ex vitro assessment using cell lysates containing cytoplasmatic GST revealed the intracellular catalytic mechanism for the nucleophilic substitution of the GO-BODIPY adduct with GSH. Confocal microscopy studies showed important differences in the cellular uptake of free BODIPY and GO-BODIPY and revealed the coexistence of GO-BODIPY, GO-BODIPY-GS, and GO-BODIPY-GS2 species inside vesicles and in the cytoplasm of the cells after 24 h of incubation. In vitro biocompatibility and safety of GO and GO-BODIPY were evaluated in 2D and 3D models of prostate adenocarcinoma cells (PC-3), where no toxicity was observed up to 100 µg ml−1 of GO/GO-BODIPY in all treated groups 24 h post-treatment (cell viability > 90%). Only a slight decrease to 80% at 100 µg ml−1 was observed after 48 h of incubation. We demonstrated the efficacy of a GO adduct containing an α-chlorine-substituted BODIPY for the simultaneous depletion of intracellular GSH and the photogeneration of reactive oxygen species using a halogen white light source (5.4 mW cm−2) with a maximum in the range of 500–800 nm, which significantly reduced cell viability (<50%) after irradiation. Our study provides a new vision on how to apply BODIPY derivates and potentiate the toxicity of PDT in prostate and other types of cancer.

The emissions of nitrogen oxides (NOx) are a serious environmental problem due to its relationship with the formation of smog, acid rain and because they are dangerous for human and animal health. These gases are produced in high quantities in diesel engines used for automotive applications, and different strategies are being used to reduce them, among which are the Selective Catalytic Reduction (SCR) systems. For its operation, it is necessary a supply of ammonia as NOx reducing agent, but the inefficiency at low temperatures of the systems used nowadays has led to the conception of the solid ammonia storage units (ASS). Unfortunately, the materials currently used, i.e. metal halides, do not meet the ammonia supply requirements at low temperatures and have problems of swelling and agglomeration. In order to find a material with better properties for its application as an ammonia sorbent material, MgCl2 composites with different carbon materials (graphite, graphene, and SWCNTs) were prepared by direct mixing and wet impregnation methods, and characterized in this work. Despite the decrease of total storage capacity, improvements were found in thermal stability and mass retention, as well as in sorption and desorption kinetics, making these materials a first result towards the improvement of the solid ammonia storage units.

Dans le cadre de la recherche sur les dispositifs post-CMOS, l'électronique moléculaire bénéficie de la polyvalence de la chimie organique,qui offre de nouvelles fonctions alliant spécificités optiques et électroniques, tout en accédant au régime de confinement quantique intrinsèque aux petites molécules. Conducteurs 1D, les nanotubes de carbone font le lien entre l’électronique des petites molécules émergente et la technologie des semi-conducteurs, tout en tirant parti de la chimie organique. Au-delà de la miniaturisation, ils offrent la possibilité de concevoir de nouveaux dispositifs pour des capteurs, l’optoélectronique et l’électronique quantique. Cependant, la plupart des études se concentrent sur leurs applications aux capteurs ou pour le photovoltaïque qui impliquent un ensemble macroscopique de nanotubes. Dans ce cas, les transferts d'excitation sont moyennés sur un ensemble statistique, ce qui empêche l'accès à leurs mécanismes fondamentaux. Il est donc nécessaire de concevoir des dispositifs fonctionnels à base de nanotubes de carbone individuels. Pour cela, les nanotubes double paroi ont de nombreux avantages sur les monoparois. En général, ils présentent une stabilité plus élevée, qui peut être d’une aide substantielle dans des expériences à haute intensité et à fort champ. Ils réalisent un système cœur-coquille: leur structure concentrique suggère leur utilisation pour réaliser indépendamment un dopage ou une fonctionnalisation des tubes intérieur et extérieur.Dans ce projet de thèse, nous étudions des transistors à effet de champ basés sur des systèmes hybrides nanotubes individuels double paroi / chromophore.Nous présentons d'abord le procédé de fabrication de transistors à effet de champ de nanotubes de carbone à paroi individuels (DWFET), qui sont ensuite caractérisés à la fois par des techniques optiques et électriques. Nous avons notamment étudié le couplage électron-phonon par spectroscopie Raman sous dopage électrostatique. Le tube métallique interne apparaît également affecté par la grille électrostatique et montre des changements significatifs de la signature Raman.Nous avons ensuite fonctionnalisé les DWFETde façon non covalente avec deux types de molécules optiquement sensibles (terpyridine d'osmium et complexe de zinc (II) métalloporphyrine). Les hybrides sont caractérisés à la fois en optique et en transport électronique. Il apparaît un transfert de charge entre les molécules et le DWNT qui joue le rôle d’une grille chimique détectable par spectroscopie Raman et transport électrique, ce qui indique que les DWFET peuvent être utilisés pour la détection de molécules. L'excitation lumineuse des molécules conduit à un dopage des hybrides et permet de plus de révéler le couplage entre les parois des nanotubes.De plus, nous avons réalisé des expériences de grille optique à longueur d'onde variable sur les dispositifs hybrides, couplant à la fois la spectroscopie Raman et des mesures de transport électrique de la température ambiante jusqu’à la température de l'hélium. Le contrôle optique du comportement électronique des hybrides est expliqué en termes de transfert de charge photo-induit entre les molécules greffées et le DWNT. Par conséquent, nos FET hybrides peuvent être utilisés comme mémoire à commande optique jusqu’au régime de transfert d'électrons uniques. / In the frame of the intense research on electronics beyond CMOS, molecular electronics offers the versatility of organic chemistry in order to tailor new functions combining optical and electronic specifications, while accessing the quantum confined regime intrinsic to small molecules. As 1D conductors, carbon nanotubes bridge the gap between small molecules electronics and semiconductor technology with great promises while being a playground for organic chemistry. Beyond miniaturization, they offer the opportunity to design new devices from accurate sensors to optoelectronic and quantum devices. However most studies focus on sensor or photovoltaic applications and thus involve a macroscopic assembly of nanotubes. This averages the excitation transfers, which prevents access to their fundamental mechanisms. This requires the design of individual carbon nanotube based functional devices. For this issue double wall carbon nanotubes have many advantages over simple SWNTs. In general, they exhibit higher stability, which can be a substantial help in high-current and high-field experiments. They realize a core-shell system: their concentric structure suggests its use for independent doping or functionalization of inner and outer tubes.In this PhD project, we demonstrate field effect transistors based on hybrid systems of individual double wall carbon nanotubes and optically sensitive molecule.We first introduce the method for making individual double wall carbon nanotube field effect transistors (DWNT FETs), which are then characterized both optically and electrically. We also studied the electron phonon coupling in the DWNT system by Raman spectroscopy with electrostatic gating. The inner metallic tube is also affected by the electrostatic gate and shows dramatic changes of the overall Raman signature.We then functionalized non covalently two kinds of optically sensitive molecules to DWNT and graphene FETs (Terpyridine Osmium complex and Zinc(II) metalloporphyrin). The hybrids are characterized both optically and electrically. Charge transfer between DWNTs and molecules plays as a chemical gating which can be detected by Raman spectroscopy as well as electrical transport measurements, which indicates that the DWNT FETs can be utilized for molecular sensing. Light excitation of the molecules leads to doping of the hybrids and reveals the coupling between the nanotube walls.Moreover, we realized wavelength dependent optical gating on the hybrid device, detected by both Raman spectroscopy and electrical transport measurements at both room temperature and helium temperature. The optical control of the hybrids’ electronic behavior will be elucidated in terms of photo-induced charge transfer between the grafted molecules and the DWNT component. As a consequence, this hybrid FETs can be used as an optically controlled memory down to single electron transfers at low temperature.

Current methods for preparing graphene quantum dots (GQDs) rely on oxidation and reducing agents or require energy-intensive and technologically demanding preconditions. Applying microwave expansion and liquid phase exfoliation (LPE) in a sample of graphite powder enabled us to prepare GQDs that exhibit strong luminescence in the blue region of the visible spectrum. The proposed technique for synthesizing GQDs is energetically undemanding and does not necessitate additional chemical components.

Supercapacitor is the best potential candidate of the energy storage system due to the superior charge or discharge efficiency, high power density (>10 kW kg-1), and long cycling life. Porous carbon materials as the promising electrode material have been widely used in supercapacitor. In fact, conventional porous carbon supercapacitor electrodes cannot fulfil the growing demand of high energy and power densities of supercapacitor. A large number of studies show that nitrogen doping can change the surface electronic structure of carbon materials, thus significantly improving the electrochemical properties. In addition to, the pore structure and morphology of carbon materials have great influence on the electrochemical performance. In this work, we firstly fabricated nitrogen-doped porous carbon nanotubes by using a simple mixed salts (NaCl/ZnCl2) activation strategy. The as-obtained porous carbon nanotubes exhibited excellent electrochemical performance in supercapacitor. Furthermore, two- dimension nitrogen-doping porous nanosheets were prepared by a salt template-assisted monomer deposition method. In this study, by optimizing the synthesis conditions, the as-obtained carbon nanosheets showed a high specific capacitance of 277 F g-1 at 1 A g-1 and excellent cycle stability retained 91 % after 10,000 cycles. / College of Engineering, Science and Technology / M. Tech.( Civil and Chemical Engineering

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Thesis. (M.Tech. (Chemistry)) -- Vaal University of Technology, 2011. / Bis(acetylacetonato)oxovanadium(IV), Manganese(III) acetylacetonate, Co-Zn and Co-Al were prepared as catalyst precursors for the synthesis of carbon materials in a catalytic chemical vapor deposition (CCVD) reactor. The carbon materials produced were characterized with Raman spectroscopy, Scanning electron microscope (SEM), Energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), High resolution transmission electron microscopy (TEM) and Thermogravimetric analysis, (TGA). Carbon material prepared from bis(acetylacetonato)oxovanadium(IV) catalyst precursor showed the presence of carbon spheres with average diameter of 104μm together with small traces of carbon nanotubes or amorphous carbon. Synthesis of bis(acetylacetonato)oxovanadium(IV) catalyst precursor yielded approximately 92% of carbon material. Carbon material prepared from Manganese(III) acetylacetonate catalyst precursor showed the presence of carbon spheres with diameter of 87.5μm. Synthesis of Manganese(III) acetylacetonate catalyst precursor yielded approximately 97% of carbon material. Carbon material produced from Co-Zn and Co-Al catalyst precursors showed the presence of carbon nanotubes with small amounts of amorphous carbon. The use of Co-Zn catalyst precursor yielded approximately 80% of carbon nanotubes, whereas Co-Al catalyst precursor yielded approximately 98% of carbon nanotubes. / Vaal University of Technology; NRF; SASOL