The rapid accumulation of municipal solid waste is a significant environmental concern in our rapidly growing world. Due to its low cost, high energy recovery and limited environmental impact anaerobic digestion (AD) is a promising solution for stabilizing the organic fraction of municipal solid waste (OFMSW). Hydrolysis is often the rate-limiting step during AD of wastes with high solid content; this step can be accelerated by pretreatment of waste prior to AD. This thesis presents the results of alkaline pretreatment of OFMSW using NaOH and KOH. Four different pH levels 10, 11, 12 and 13 at two temperatures 23±1°C and 80±1°C were examined to study the effects of the pretreatment on (i) enhancing the solubility of the organic fraction of the waste, and (ii) enhancing the AD process and the biogas production. The effects on solubility were investigated by measuring changes in the soluble COD (SCOD) concentrations of pretreated wastes and the enhanced AD was investigated by measuring volatile solids (VS) destruction, total COD (TCOD) and SCOD removal in addition to biogas and methane production using biochemical methane potential (BMP) assay and semi-continuous laboratory reactor experiments. Pretreatment at pH 13 at 80±1°C demonstrated the maximum solubility for both NaOH and KOH pretreated samples; however the BMP analysis demonstrated that pretreatment at pH 12 at 23±1°C showed the greatest biogas yield relative to the removed VS for both chemicals. Thus pretreatment at pH 12 at 23±1°C using NaOH and KOH were examined using semi-continuous reactors at three different HRTs: 10, 15 and 20 days. Pretreatment demonstrated a significant improvement in the AD performance at SRTs of 10 and 15 days.

The rapid accumulation of municipal solid waste is a significant environmental concern in our rapidly growing world. Due to its low cost, high energy recovery and limited environmental impact anaerobic digestion (AD) is a promising solution for stabilizing the organic fraction of municipal solid waste (OFMSW). Hydrolysis is often the rate-limiting step during AD of wastes with high solid content; this step can be accelerated by pretreatment of waste prior to AD. This thesis presents the results of alkaline pretreatment of OFMSW using NaOH and KOH. Four different pH levels 10, 11, 12 and 13 at two temperatures 23±1°C and 80±1°C were examined to study the effects of the pretreatment on (i) enhancing the solubility of the organic fraction of the waste, and (ii) enhancing the AD process and the biogas production. The effects on solubility were investigated by measuring changes in the soluble COD (SCOD) concentrations of pretreated wastes and the enhanced AD was investigated by measuring volatile solids (VS) destruction, total COD (TCOD) and SCOD removal in addition to biogas and methane production using biochemical methane potential (BMP) assay and semi-continuous laboratory reactor experiments. Pretreatment at pH 13 at 80±1°C demonstrated the maximum solubility for both NaOH and KOH pretreated samples; however the BMP analysis demonstrated that pretreatment at pH 12 at 23±1°C showed the greatest biogas yield relative to the removed VS for both chemicals. Thus pretreatment at pH 12 at 23±1°C using NaOH and KOH were examined using semi-continuous reactors at three different HRTs: 10, 15 and 20 days. Pretreatment demonstrated a significant improvement in the AD performance at SRTs of 10 and 15 days.

The rapid accumulation of municipal solid waste is a significant environmental concern in our rapidly growing world. Due to its low cost, high energy recovery and limited environmental impact anaerobic digestion (AD) is a promising solution for stabilizing the organic fraction of municipal solid waste (OFMSW). Hydrolysis is often the rate-limiting step during AD of wastes with high solid content; this step can be accelerated by pretreatment of waste prior to AD. This thesis presents the results of alkaline pretreatment of OFMSW using NaOH and KOH. Four different pH levels 10, 11, 12 and 13 at two temperatures 23±1°C and 80±1°C were examined to study the effects of the pretreatment on (i) enhancing the solubility of the organic fraction of the waste, and (ii) enhancing the AD process and the biogas production. The effects on solubility were investigated by measuring changes in the soluble COD (SCOD) concentrations of pretreated wastes and the enhanced AD was investigated by measuring volatile solids (VS) destruction, total COD (TCOD) and SCOD removal in addition to biogas and methane production using biochemical methane potential (BMP) assay and semi-continuous laboratory reactor experiments. Pretreatment at pH 13 at 80±1°C demonstrated the maximum solubility for both NaOH and KOH pretreated samples; however the BMP analysis demonstrated that pretreatment at pH 12 at 23±1°C showed the greatest biogas yield relative to the removed VS for both chemicals. Thus pretreatment at pH 12 at 23±1°C using NaOH and KOH were examined using semi-continuous reactors at three different HRTs: 10, 15 and 20 days. Pretreatment demonstrated a significant improvement in the AD performance at SRTs of 10 and 15 days.

The rapid accumulation of municipal solid waste is a significant environmental concern in our rapidly growing world. Due to its low cost, high energy recovery and limited environmental impact anaerobic digestion (AD) is a promising solution for stabilizing the organic fraction of municipal solid waste (OFMSW). Hydrolysis is often the rate-limiting step during AD of wastes with high solid content; this step can be accelerated by pretreatment of waste prior to AD. This thesis presents the results of alkaline pretreatment of OFMSW using NaOH and KOH. Four different pH levels 10, 11, 12 and 13 at two temperatures 23±1°C and 80±1°C were examined to study the effects of the pretreatment on (i) enhancing the solubility of the organic fraction of the waste, and (ii) enhancing the AD process and the biogas production. The effects on solubility were investigated by measuring changes in the soluble COD (SCOD) concentrations of pretreated wastes and the enhanced AD was investigated by measuring volatile solids (VS) destruction, total COD (TCOD) and SCOD removal in addition to biogas and methane production using biochemical methane potential (BMP) assay and semi-continuous laboratory reactor experiments. Pretreatment at pH 13 at 80±1°C demonstrated the maximum solubility for both NaOH and KOH pretreated samples; however the BMP analysis demonstrated that pretreatment at pH 12 at 23±1°C showed the greatest biogas yield relative to the removed VS for both chemicals. Thus pretreatment at pH 12 at 23±1°C using NaOH and KOH were examined using semi-continuous reactors at three different HRTs: 10, 15 and 20 days. Pretreatment demonstrated a significant improvement in the AD performance at SRTs of 10 and 15 days.

Continuous population growth and rapid industrial advancement and development have paved the way for ever increasing environmental pollution. At present, water pollution is a serious global issue that threatens environmental sustainability. The contamination of aquatic bodies with potentially toxic organic and inorganic substances are the result of world-wide anthropogenic activities. These pollutants can have detrimental health consequences on humans and ecosystems. Over the past decades, techniques such as chemical precipitation, ion-exchange, adsorption, membrane filtration, and electrocoagulation-flocculation have been developed and employed for the treatment of drinking and wastewater. Among the currently available techniques, pollutant removal by adsorption is most promising due to its cost-effectiveness, simplicity in operation, environmental friendliness, and abundance of adsorbents. This study emphasized the utilization of biochar (BC), after appropriate surface modification, for the removal of potentially toxic contaminants. In the first study, a base activated biochar was synthesized by treating the biochar with potassium hydroxide (KOH) at 700 ℃ in a muffle furnace for 1 h. The resulting high surface area biochar (KOHBC) was used for the removal of Cr(VI), Pb(II) and Cd(II). In the second study, a biochar-supported polyaniline hybrid was synthesized for aqueous chromium and nitrate adsorption. Introduction of amine and imine groups to the biochar facilitated the removal of these contaminants. In the final study, a composite containing Fe-Ti oxide/biochar (Fe2TiO5/BC) was synthesized for sorptive removal of metal cations, oxy anions, inorganics, and organic contaminants from aqueous solutions. Additionally, this composite was used as a photocatalyst towards aqueous methylene blue (MB) degradation. The surface chemistry and composition of these adsorbents were examined by PZC SEM, TEM, XPS, FTIR, TGA, elemental analysis, and surface area measurements.

In this study production and characterization of activated carbon from an agricultural waste, pistachio-nut shells, was investigated. To determine optimum production conditions by chemical activation method, effect of tempreature (300, 500, 700 and 900 oC) and effect of impregnation ratio (1:1, 2:1 and 3:1 as activation agent:sample) were investigated by applying two different methods (raw material activation and char activation) and with two different activation agents (phosphoric acid and potassium hydroxide). To produce activated carbon, all the impregnated samples were heated to the final activation temperature under a continuous nitrogen flow (100 cm3/min) and at a heating rate of 10 oC/min and were held at that temperature for 1 hour. Pore structures of activated carbons were determined by N2 adsorption and micro-mesopore analysis was made by &ldquo / Non-local Density Functional Theory&rdquo / and &ldquo / Monte Carlo Simulation&rdquo / method (NLDFT-Monte Carlo Simulation Method). BET surface areas of produced activated carbons were found from N2 adsorption data in the relative pressure range of 0.01 to 0.15. BET surface areas of phosphoric acid activated carbons by raw material activation method were found between 880 and 1640 m2/g. The highest value of the BET surface area was obtained in the case of the activated carbon which was produced with an impregnation ratio of 3/1 (g H3PO4/g raw material), at an activation temperature of 500 oC. The repeatibility was also investigated on phosphoric acid activated carbons which were produced with conventional raw matererial activation method. Results showed that, both the BET surface area values and pore size distributions were consistent among themselves. On the other hand char activation experiments with phosphoric acid produced activated carbons having lower BET surface areas than the ones obtained with raw material activation method by creating mesoporous structure. When the same char activation method was tried with potassium hydroxide, it was concluded that elevated temperatures could help in producing activated carbons with high BET surface areas by creating microporous structure. Results also showed that properties of activated carbon such as ash content, slurry pH value, true density, elemental composition, methylene blue number and surface morphology were strongly affected by both production conditions and production method, as pore structure was affected considerably.

Submitted by Adriely Bruce (adriely_bruce@hotmail.com) on 2016-12-02T14:22:37Z No. of bitstreams: 1 Dissertação - Gleicyanne O. S. Portela.pdf: 22271229 bytes, checksum: 080a862aceacc66dfad8d9ac34c508bf (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2016-12-02T19:19:50Z (GMT) No. of bitstreams: 1 Dissertação - Gleicyanne O. S. Portela.pdf: 22271229 bytes, checksum: 080a862aceacc66dfad8d9ac34c508bf (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2016-12-02T19:20:26Z (GMT) No. of bitstreams: 1 Dissertação - Gleicyanne O. S. Portela.pdf: 22271229 bytes, checksum: 080a862aceacc66dfad8d9ac34c508bf (MD5) / Made available in DSpace on 2016-12-02T19:20:26Z (GMT). No. of bitstreams: 1 Dissertação - Gleicyanne O. S. Portela.pdf: 22271229 bytes, checksum: 080a862aceacc66dfad8d9ac34c508bf (MD5) Previous issue date: 2016-04-01 / The usage of natural fibers as reinforcement in cementitious matrices has been an alternative to replacing the synthetic fibers. In this work jute fiber were characterized and added in composite. For the production of geopolymer, the activators were potassium hydroxide and potassium silicate hydroxide mixed with metakaolin, cement and sand. Characterization tests utilizing x-ray fluorescence techniques (XFR), X-ray diffractometry (XRD), chemical and physical tests, tensile and flexural tests and analyzis of the microstructu e by scanning electron microscopy (SEM) were performed for characterization of materials. Compressive strength tests on the matrix were performed at the ages of 7, 14 and 28 days, and the samples had a maximum performance of compressive strength at 58,29 MPa. The composites reinforced with three layers of jute fabric were submitted to mechanical tests after 14days and showed a flexural behavior with maximum stress of 21.4 MPa. The results indicated that the use of natural fibers increased mechanical performance of traction and flexion geopolymer composite. / O uso de fibras naturais como reforço em matrizes cimentícias tem sido uma alternativa para substituição das fibras sintéticas. Neste trabalho, as fibras de juta foram caracterizadas e adicionadas compósitos. Para a produção dos geopolímeros os ativadores foram o hidróxido de potássio e silicato de hidróxido de potássio, misturados a metacaulinita, cimento e areia. Ensaios de caracterização utilizando técnicas de Fluorescência de raio-x (FRX), Difratometria de raio-x (DRX), ensaios químicos e físicos, ensaios de tração e flexão e analise da microestrutura por microscopia eletrônica de varredura (MEV) foram realizados para a caracterização dos materiais. Os testes de resistência à compressão na matriz foram realizados nas idades de 7, 14 e 28 dias, amostras apresentaram desempenho máximo de resistência à compressão de 58,29 MPa. Os compósitos reforçados com três camadas de tecido de juta foram submetidos aos ensaios mecânicos após 14 dias e apresentaram comportamento à flexão com tensão máxima de 21,4 Mpa. Os resultados obtidos indicaram que o uso de fibras naturais aumentou o desempenho mecânico de tração e flexão do compósito geopolímero.

Cette thèse porte sur l’amélioration de la résistance au flux laser de la surface descomposants optiques en silice en régime nanoseconde. Ce matériau est utilisé sur lesinstallations de laser de puissance telles que le Laser Mégajoule. Pour augmenter la durée de viedes composants optiques et garantir le fonctionnement nominal de cette installation,l’endommagement laser doit être maîtrisé. Il s’agit d’une dégradation irréversible de la surfacedes composants causée par l’interaction entre le faisceau laser et des défauts précurseurs. Cesderniers sont une conséquence de la synthèse de la silice puis du polissage des composants etleur présence peut être limitée par une action de traitement chimique réalisée à l’issue dupolissage qui consiste à éroder la surface de silice à l’aide d’une solution chimique. Cette érosionne doit cependant pas dégrader la qualité de la surface polie et ses propriétés optiques. Cettethèse se concentre sur la réalisation de cette étape de traitement chimique et se décompose entrois études. La première porte sur la caractérisation de la pollution induite en surface par lepolissage et sa suppression par le traitement chimique. La seconde et la troisième analysentl’impact des traitements chimiques respectivement sur les propriétés optiques de la surface etsur les rayures de polissage. Ces études nous permettent d’évaluer l’influence des différentsparamètres du traitement chimique, tels que la solution, le système de mise en oeuvre etl’épaisseur érodée, sur les performances apportées aux composants optiques. Finalement,l’ensemble de ces connaissances nous conduit à proposer un traitement chimique optimisé quiaméliore la tenue au flux des composants optiques sans dégrader leurs propriétés optiques. / In this thesis, laser-induced damage resistance improvement of fused silica opticsis investigated in the nanosecond regime. This material is used on high power laser facilitiessuch as the Laser Mégajoule. In order to improve the optics life time and to ensure the nominaloperation of this facility, laser induced damage has to be controlled. This phenomenon is anirreversible modification of the components surface because of the interaction between the laserbeam and precursors defects. These defects are a consequence of the synthesis of silica and thepolishing of the optics and their presence can be reduced by a wet etching. This process consistsin an erosion of the surface using a chemical solution however optical properties must remainunchanged. In this thesis, we focus on the wet etching process and we conduct three studies. Thefirst one is about the characterization of the polishing induced contamination and the capabilityof a wet etching to remove it from the surface. The second and the third analyzes are about theimpact of the wet etching respectively on the surface and on the scratches. These studies allowus to evaluate the influence of the wet etching parameters as the chemical solution, the systemused and the deep etched. Finally, the highlights obtained thanks to these studies enable tooptimize the wet etching process and improve the laser induced damage resistance ofcomponents without compromising their optical properties.

Nowadays, the systems that allow simultaneous employment of both focused electron and ion beams are very important tools in the field of micro- and nanotechnology. In addition to imaging and analysis, they can be used for lithography, which is applied for preparation of structures with required shapes and dimensions at the micrometer and nanometer scale. The first part of the thesis deals with one lithographic method – focused electron or ion beam induced deposition, for which a suitable adjustment of exposition parameters is searched and quality of deposited metal structures in terms of shape and elemental composition studied. Subsequently, attention is paid also to other types of lithographic methods (electron or ion beam lithography), which are applied in preparation of etching masks for the subsequent selective wet etching of silicon single crystals. In addition to optimization of mentioned techniques, the application of etched silicon surfaces for, e.g., selective growth of metal structures has been studied. The last part of the thesis is focused on functional properties of selected 2D or 3D structures.

This master's thesis deals with alkaline battery characteristics and it has special consideration of nickel-cadmium cells. There are three main experimental parts in this paper. First one is concerned with positive electrode materials properties and is aimed to investigate impact of magnesium ions formed into nickel hydroxide electrode structure. Second part deals with battery charging/discharging and response measurement tool design. National Instruments hardware PXI modules for data acquisition was used and program in LabView environment was made. Last one is concerned with nickel-cadmium cell properties changes during increased temperature stressing. Investigation of cell self-charge changes during lithium hydroxide addition into electrolyte was made.