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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1001

Mise au point dun réacteur biphasique eau/huile de silicone destiné au traitement des composés organiques volatils hydrophobes au sein des effluents gazeux/Development of a water / silicone-oil two-phase partitioning bioreactor for the treatment of hydrophobic volatile organic compounds from gas effluents

ALDRIC, Jean-Marc 24 August 2009 (has links)
Récemment, de nombreuses recherches ont été dévolues à la mise au point de réacteurs biphasiques, perçus comme une nouvelle technologie pour le traitement des polluants organiques dans les effluents gazeux. Ces réacteurs impliquent lutilisation dune seconde phase non aqueuse pour améliorer la solubilité et le transfert de masse des composés hydrophobes. Dans ce travail, nous avons développé un réacteur biphasique agité utilisant lhuile de silicone comme seconde phase. Initialement, Rhodococcus erythropolis T 902.1 a été sélectionné sur base de sa capacité à dégrader lisopropylbenzène (IPB), un composé choisi comme modèle représentatif de la famille du benzène. Deuxièmement, le transfert de masse de loxygène et de lIPB a été étudié en relation avec les conditions hydrodynamiques du réacteur et le type dhuile de silicone. Lutilisation dune proportion de 10 % dhuile de faible viscosité (10cSt) naffecte pas significativement le transfert de masse de loxygène. Cependant la grande solubilité de lIPB dans lhuile de silicone conduit à une forte augmentation du potentiel de transfert, spécialement pour les proportions en huile les plus élevées. Néanmoins, il ne semble pas utile de dépasser une proportion de 10 % car le KLaIPB et le KLaO2 diminuent drastiquement pour des proportions supérieures. Lexistence dune concentration optimale en élément biotique apparaît également. En effet, les concentrations optimales en biomasse (B) et extrait surfactant (ES) peuvent être évaluées à, respectivement 0,5 g/L et 0,7 g/L, elles assurent une valeur maximale du coefficient global de transfert de masse de loxygène (KLaO2). Plus spécifiquement, lES augmente laire interfaciale « a » en diminuant le diamètre des bulles tandis que la biomasse la diminue dès quune concentration de 1 g/L est atteinte. Au contraire, lES agit négativement sur le KL tandis que la biomasse laméliore globalement. En terme de performance, il est clairement montré que la taux de biodégradation de lIPB est davantage corrélé au débit gazeux de leffluent quà la concentration en polluant. Le réacteur biphasique a été suivi sur une période de 38 jours afin de caractériser son comportement à moyen terme pour différentes conditions opératoires. Lors dune phase dalimentation transitoire (10h/j), la capacité moyenne délimination est denviron 240 g/m3 pour une charge massique de 390 g/m3. Finalement, une approche originale a été développée en utilisant un bioréacteur de type scale-down pour reproduire les conditions hydrodynamiques rencontrées dans les réacteurs industriels. Il est clairement démontré que le polluant (IPB) affecte négativement lextrapolation en augmentant la vitesse de séparation de phase. Cependant cet impact négatif est largement compensé par la présence déléments biotiques qui stabilise fortement le système biphasique, rendant totalement envisageable lextrapolation à grande échelle. En conclusion, lutilisation dun réacteur biphasique eau-huile de silicone pour lélimination de concentrations élevées (~ 6g/m3) en polluants hydrophobes est adéquate. Le réacteur proposé présente de réelles opportunités pour le traitement biologique deffluents pollués par des composés hydrophobes. Son utilisation pourrait être envisagée lorsque loxydation thermique savère trop onéreuse ou lorsque les biofiltres classiques atteignent leurs limites ( >1 g/Nm3 et une charge volumique de 90m3/m3.h.)./Recently, a lot of research has been devoted to the study of two-phase partitioning bioreactors (TPPB) as new technology for xenobiotic degradation in gaseous effluents. These reactors involve the use of a second non-aqueous phase to improve the solubility and transfer of hydrophobic compounds. In this work, we have developed a stirred two-phase partitioning bioreactor using silicone oil as second phase. Initially, Rhodococcus erythropolis T 902.1 was selected on the basis of its capacity to metabolize isopropyl-benzene (IPB), used as representative of the benzene-containing compounds. Secondly, the mass transfer of both IPB and oxygen has been considered with relation to their influence on the hydrodynamics of the reactor and the type of silicone oil used. The addition of 10% low viscosity silicone oil (10 cSt) in the reactor does not significantly affect the oxygen transfer rate. The very high solubility of IPB in the silicone oil leads to an enhancement of the driving force term, especially when high proportion of silicone oil are used. However, it is not necessary to use a volume fraction higher than 10% since KLaIPB and KLaO2 decrease sharply at above such proportion. In addition, an optimal concentration appeared to exist for both biotic components, respectively 0,5 g/L and 0,7 g/L for biomass (B) and surfactant extract (SE) when the global mass transfer coefficient (KLa) of oxygen was measured in the TPPB. More specifically, SE improved the interfacial area a by decreasing the bubble diameter, while B reduced it at concentrations up to 1 g/L. In contrast, the SE concentration acted negatively on KL, while it was favoured by the B concentration. In term of performances, it was clearly shown that the biodegradation rate is more directly related to the inlet flow of IPB than to the concentration of IPB in the inlet gas. The TPPB was monitored for 38 days to characterise its behaviour under several operational conditions. During an intermittent loading phase (10 h/day), the average elimination capacity remained above 240 g/m3.h for an average IPB inlet load of 390 g/m3. h. Finaly, an original approach was developed using a scale-down bioreactor allowing to reproduce the hydrodynamics encountered under full scale TPPB. It was clearly shown that the IPB affects negatively the scaling-up of the process by increasing the speed of phase partitioning. However, this negative impact was strongly compensated by the presence of biotic compounds stabilizing the two phase system and rendering the scaling-up process feasible. In conclusion, the use of a water-silicone oil TPPB to remove a high inlet load of IPB was successful. The proposed reactor retains a high potential for the biological treatment of gas effluents polluted by hydrophobic aromatic compounds. The suggested process might be applied in the range of concentration and flow where thermal oxidation is too expensive (between 1 and 7 g/Nm3) or when the biofilters are usually limited, i.e. to treat a polluted effluent concentrated with > 1 g/Nm3 at a flow of 90m3/m3.h.
1002

The Sink-Effect in Indoor Materials : Mathematical Modelling and Experimental Studies

Hansson, Peter January 2003 (has links)
In this thesis the sink-effect in indoor materials wasstudied using mathematical modelling and experimental studies.The sink-effect is a concept which is commonly used tocharacterise the ability of different indoor materials to sorbcontaminants present in the indoor air. The sorption process ismore or less reversible, i.e. molecules sorbed in materials athigh contaminant concentrations may again be desorbed at lowerconcentrations. Knowledge of the sorption capacity of materialsand the rate at which sorption and desorption takes place is offundamental importance for mathematical simulation of indoorair quality. The aim of this work is to contribute withknowledge about how the sink-effect can be described inmathematical terms and how the interaction parametersdescribing the sorption capacity and sorption/desorptionkinetics can be determined. The work has been of amethodological nature. The procedure has been to set upphysically sound mathematical models of varying complexity andto develop small-scale chamber experiments. Two differentdynamic chamber methods have been used. One is based on amodified standard FLEC-chamber while the other uses a chamberwith two compartments, one on each side of the material. The"twin-compartment" method was designed due to the observationthat the contaminant readily permeated straight through theselected materials, which resulted in uncontrolled radiallosses in the FLEC-chamber. In order to be useful forcomparison between experiments and calculations and parameterfitting, the boundary conditions in the chambers must beprecisely known and controlled. This matter has shown to be themost crucial and difficult problem in the research. A varietyof mathematical models for the sink-effect have been proposed.In some models advanced fluid simulations were used in order totest the influence ofill-defined flow boundary conditions. Theaim of the modelling is to find a formulation with a minimum ofinteraction parameters, which is generally useful, i.e. both insmall-scale laboratory environments and in full-scale like anoffice room. Estimated model parameters are shown to be able toyield a reasonably good fit to experimental data for thesorption process but a less satisfactory fit for the desorptionprocess. <b>Keywords:</b>sink-effect, sorption, adsorption, diffusion,indoor air quality, volatile organic compounds, VOC,contaminants, building materials
1003

Utsläpp av Flyktiga Organiska Föreningar och Partiklar i Falun : Trafiken och industrins bidrag av PM10 och VOC

Björkman, Joanna January 2009 (has links)
Emissions from Particles and Volatile Organic Compounds (VOC) in Falun.-How is the emission divided between particles and VOC? This study investigates the air quality in Falun, a small city in central Sweden, with a focus on particles and volatile organic compounds (VOC). Falun is located in a valley which makes it sensitive to inversions, when the vertical mixing of air over the city is prevented. When this happens emissions over the city can stay for days and the pollution levels can be high. The report is based upon a literature review, calculation of emissions from traffic and a survey of industrial emissions. Emission of VOCs can be dangerous to people and contributes to the production of ground- level ozone. Particles can be a carrier for other dangerous compounds. The result shows that high pollution levels caused by inversions can happen. The temperature, wind and temperature differences show that inversions during the winter months are possible up to half of the time. Emissions from cars and industries are a problem. The municipality forced to control air pollution and in Swedish law there is a threshold value for both particles and the volatile organic compounds benzene. Spreading of pollution in air in Falun is centered around the emission sourses. Because it´s hard to prevent inversions, the municipality must focus on reducing emission of pollutants. This can be done through road planning and diverting traffic to other routes around the city.
1004

The influence of soil and contaminant properties on the efficiency of physical and chemical soil remediation methods

Jonsson, Sofia January 2009 (has links)
A vast number of sites that have been contaminated by industrial activities have been identified worldwide. Many such sites now pose serious risks to humans and the environment. Given the large number of contaminated sites there is a great need for efficient, cost-effective  remediation methods. Extensive research has therefore been focused on the development of such methods. However, the remediation of old industrial sites is challenging, for several reasons. One major  problem is that organic contaminants become increasingly strongly sequestered as they persist in the soil matrix for a long period of time. This process is often referred to as ‘aging’, and leads to decreasing availability of the contaminants, which also affects the remediation efficiency. In the work underlying this thesis, the influence of soil and contaminant properties on the efficiency of various physical and chemical soil remediation methods was investigated. The investigated contaminants were polycyclic aromatic hydrocarbons (PAHs), polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs). Briefly, the results show that as the size of soil particles decreases the contaminants become more strongly sorbed to the soil’s matrix, probably due to the accompanying increases in specific surface area. This affected the efficiency of the removal of organic pollutants by both a process based on solvent washing and processes based on chemical oxidation. The sorption strength is also affected by the hydrophobicity of the contaminants. However, for a number of the investigated PAHs their chemical reactivity was found to be of greater importance for the degradation efficiency. Further, the organic content of a soil is often regarded as the most important soil parameter for adsorption of hydrophobic compounds. In these studies the effect of this parameter was found to be particularly pronounced for the oxidation of low molecular weight PAHs, but larger PAHs were strongly adsorbed even at low levels of organic matter. However, for these PAHs the degradation efficiency was positively correlated to the amount of degraded organic matter, probably due to the organic matter being oxidized to smaller and less hydrophobic forms. The amount of organic matter in the soil had little effect on the removal efficiency obtained by the solvent-washing process. However, it had strong influence on the performance of a subsequent, granular activated carbon-based post-treatment of the washing liquid. In conclusion, the results in this thesis show that remediation of contaminated soils is a complex process, the efficiency of which will be affected by the soil matrix as well as the properties of the contaminants present at the site. However, by acquiring thorough knowledge of the parameters affecting the treatability of a soil it is possible to select appropriate remediation methods, and optimize them in terms of both remediation efficiency and costs for site- and contaminant-specific applications.
1005

Two-Phase Partitioning System Using Elvax 40W Polymer for the Biodegradation of Aqueous Phenols

Ghode, Amit Suresh 01 December 2010 (has links)
A solid-liquid two phase partitioning system (TPPS) is a new technology platform for destroying toxic organic compounds. TPPS have traditionally been operated by using an immiscible organic phase which partitions organic compounds into the aqueous phase. TPPS using an immiscible organic phase suffers from several limitations such as the organic phase could be biodegradable and hence only certain compatible microbial strains could be used. This therefore, eliminates the desired use of mixed microbial populations for efficient degradation. A solid-liquid two phase partitioning system, in which solid polymeric beads replace liquid organic phase, appears to have benefits over the traditional liquid-liquid partitioning systems. The choice of suitable polymeric material should have similar absorption properties as the liquid organic solvent but have the added benefit of being able to be used with mixed microbial population. In this study, poly (ethylene-co-vinyl acetate), brand name ELVAX 40W, was selected as the test polymer in an effort to lower the concentrations of selected analytes; phenol, 4- nitrophenol and o-cresol in aqueous solutions. Studies were performed to determine the degree of partitioning using HPLC and UV-VIS. Kinetic studies were also performed and illustrated a first order dependence on the absorption of the phenols tested. Activation energies were also determined for each analyte. Rate constants were on the order of 10-4 min-1. Activation energy ranged from 19-46 kJ/mol. Regeneration tests showed that a release of analyte from the polymer is possible when the beads are placed in water. Therefore the ability to reuse the polymer is possible and therefore cost efficient. The polymer was observed to lower high concentrations up to 2000 ppm suggesting its potential use to treat the high concentrations of toxic organic compounds.
1006

Analysis of Kyrock for Leaching of Impurities in Synthetic Rainwater

Kasulavada, Santhosh Kumar 01 August 2013 (has links)
Kyrock is a coarse grained sandstone with a complex mixture of organic and inorganic compounds. Mining of Kyrock is for use in road construction and roofing. Kyrock samples were analyzed using scanning electron microscopy to obtain elemental analysis. High levels of carbon indicate the presence of organic compounds. Analysis of an acid digestion of the samples using inductively coupled plasma spectroscopy showed inorganic compounds such as titanium oxide, vanadium oxide along with traces of arsenic. Elemental analysis of samples indicates a percent of carbon, and sulfur with no notable traces of nitrogen. Pyrolysis of the samples was done using gas chromatography mass spectroscopy with a gradual increase in temperature to 160o C resulted in the release of inorganic and organic compounds. Synthetic rainwater was prepared to examine the leaching of compounds and the leachate was analyzed using liquid chromatography mass spectroscopy and gas chromatography mass spectroscopy.
1007

Bi-Based Oxide Anodes for Direct Hydrocarbon SOFCs at Intermediate Temperatures

Sano, Mitsuru, Harada, Ushio, Hibino, Takashi, Hashimoto, Atsuko, Hirabayashi, Daisuke January 2004 (has links)
No description available.
1008

Design and Performance of a VOC Abatement System Using a Solid Oxide Fuel Cell

Borwankar, Dhananjai January 2009 (has links)
There has always been a desire to develop industrial processes that minimize the resources they use, and the wastes they generate. The problem is when new guidelines are forced upon long established processes, such as solvent based coating operations. This means instead of integrating an emission reduction technology into the original design of the process, it is added on after the fact. This significantly increases the costs associated with treating emissions. In this work the ultimate goal is the design of an “add-on” abatement system to treat emissions from solvent based coating processes with high destruction efficiency, and lower costs than systems in current use. Since emissions from processes that utilize solvent based coatings are primarily comprised of volatile organic compounds (VOCs), the treatment of these compounds will be the focus. VOCs themselves contain a significant amount of energy. If these compounds could be destroyed by simultaneously extracting the energy they release, operational costs could be substantially reduced. This thesis examines the use of model-based design to develop and optimize a VOC abatement technology that uses a Solid Oxide Fuel Cell (SOFC) for energy recovery. The model was built using existing HYSYS unit operation models, and was able to provide a detailed thermodynamic and parametric analysis of this technology. The model was validated by comparison to published literature results and through the use of several Design of Experiment factorial analyses. The model itself illustrated that this type of system could achieve 95% destruction efficiency with performance that was superior to that of Thermal Oxidation, Biological Oxidation, or Adsorption VOC abatement technologies. This was based upon design criteria that included ten year lifecycle costs and operational flexibility, as well as the constraint of meeting (or exceeding) current regulatory thresholds.
1009

Design and Performance of a VOC Abatement System Using a Solid Oxide Fuel Cell

Borwankar, Dhananjai January 2009 (has links)
There has always been a desire to develop industrial processes that minimize the resources they use, and the wastes they generate. The problem is when new guidelines are forced upon long established processes, such as solvent based coating operations. This means instead of integrating an emission reduction technology into the original design of the process, it is added on after the fact. This significantly increases the costs associated with treating emissions. In this work the ultimate goal is the design of an “add-on” abatement system to treat emissions from solvent based coating processes with high destruction efficiency, and lower costs than systems in current use. Since emissions from processes that utilize solvent based coatings are primarily comprised of volatile organic compounds (VOCs), the treatment of these compounds will be the focus. VOCs themselves contain a significant amount of energy. If these compounds could be destroyed by simultaneously extracting the energy they release, operational costs could be substantially reduced. This thesis examines the use of model-based design to develop and optimize a VOC abatement technology that uses a Solid Oxide Fuel Cell (SOFC) for energy recovery. The model was built using existing HYSYS unit operation models, and was able to provide a detailed thermodynamic and parametric analysis of this technology. The model was validated by comparison to published literature results and through the use of several Design of Experiment factorial analyses. The model itself illustrated that this type of system could achieve 95% destruction efficiency with performance that was superior to that of Thermal Oxidation, Biological Oxidation, or Adsorption VOC abatement technologies. This was based upon design criteria that included ten year lifecycle costs and operational flexibility, as well as the constraint of meeting (or exceeding) current regulatory thresholds.
1010

On-Metal Synthesis of Some Aryl Substituted Rhenium &#951<sup>5</sup> Cyclopenta[C] Pyridazyl Complexes

Sriramulu, Phenahas Gandu 01 August 2010 (has links)
Heterocyclic organic and organometallic compounds (e.g. polypyrrole) and their derivatives have been of great interest for conductive polymers due to their novel properties and environmental stability as compared to non-aromatic analogs (e.g. polyacetylene). We are interested in synthesizing organometallic pyridazines and rhenium pyridazyl complexes for polymer research. SeveraI5,6-fused ring pyridazines (1,2-CsH3(CRNH)(CRN) have been synthesized and characterized. Additionally, pyridazyl complexes of rhenium were synthesized in three steps beginning from fulvenes 1,2-CsH3(COHR)(COR). On-Metal synthesis and characterization of (Re(CO)3 {1,2- CSH3(CRN)(CRN)}] (R=C6RtOMe, C6RtCI, C4H30) and some off-metal pyridazines are reported here. Our research is focused on synthesis of a variety of 5,6- fused ring pyridazines which will serve as synthetic models and building blocks for organic and organometallic conducting polymers. Our research focused on synthesis of 5 membered pyridazines and their organometallic rhenium complexes for polymer studies. Several aryl-substituted 5,6- fused ring pyridazines have been synthesized and characterized.

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