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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.
1

Chemical fingerprinting of naphthenic acids by comprehensive two-dimensional gas chromatography mass spectrometry at reclamation sites in the Alberta oil sands

Bowman, David Thomas January 2017 (has links)
The processing of bitumen in the Athabasca oil sands region (AOSR) produces extensive volumes of oil sands process-affected water (OSPW) and tailings, which are stored within tailings ponds and settling basins to promote the consolidation of solids and the recycling of water. Oil sands operators are actively investigating dry and wet reclamation strategies in order to reduce their inventory of tailings and return disturbed land back to its original state. An important component of the reclamation of tailings is understanding the environmental fate of naphthenic acids (NAs), which are considered the most toxic constituents of OSPW and tailings. However, since NAs exist as a complex mixture comprised of thousands of compounds from dozens of chemical classes, the characterization of NAs within environmental samples poses significant challenges to analytical chemists. This dissertation is focused on the characterization of naphthenic acids by comprehensive two-dimensional gas chromatography coupled to mass spectrometry (GC×GC/MS). GC×GC/MS offers unparalleled chromatographic separation and peak capacity and has been used in recent years to resolve individual constituents within complex mixtures, including structural isomers. Since the biodegradation and toxicity of NAs is structure-specific and can vary between structural isomers, the profiling of individual NAs by GC×GC/MS is expected to enhance the monitoring of NAs within environmental samples impacted by oil sands activity. In this thesis, GC×GC coupled with time-of-flight mass spectrometry (TOFMS) was used to structurally elucidate a number of ‘unknown’ classical and sulfur-containing naphthenic acids by interpretation of their electron ionization (EI) mass spectra and, if available, confirmed by comparison with the spectra of references standards. GC×GC/TOFMS was also utilized as a fingerprinting tool to assess the temporal and spatial variability at two reclamation sites in the AOSR: Syncrude’s Sandhill Fen reclamation site and Base Mine Lake. Lastly, a methodology was developed which coupled GC×GC with a high resolution quadrupole time-of-flight mass spectrometer (QTOFMS) for the improved profiling of NAs. GC×GC/QTOFMS is advantageous for the monitoring of NAs since it can provide useful fingerprints via isomer distributions, differentiate NAs from several chemical classes, and provide a global overview of the elemental compositions (assigned by mass accuracy) within NA mixtures. / Thesis / Doctor of Philosophy (PhD)
2

[en] CHEMICAL CHARACTERIZATION OF PARTICULATE MATTER (PM10) COLLECTED IN STRATEGIC POINTS IN THE METROPOLITAN REGION OF RIO DE JANEIRO / [pt] CARACTERIZAÇÃO QUÍMICA DE MATERIAL PARTICULADO (PM10) COLETADO EM PONTOS ESTRATÉGICOS DA REGIÃO METROPOLITANA DO RIO DE JANEIRO

BEATRIZ SILVA AMARAL 15 May 2019 (has links)
[pt] O objetivo deste estudo foi determinar a concentração de metais, compostos orgânicos e inorgânicos por suspensão aquosa e análise dos metais por abertura ácida presentes nas amostras de PM10 coletadas em áreas urbanas, industrial e rural da Região Metropolitana do Rio de Janeiro. A concentração de PM10 foi determinada por análise gravimétrica. Espécies inorgânicas e orgânicas presentes nos extratos aquosos foram determinadas por cromatografia de íons e carbono orgânico total (TOC). Os extratos ácidos, e também os aquosos, foram analisados por ICP-MS (espectrometria de massa com plasma indutivamente acoplado) e por ICP OES (espectrometria de emissão óptica com plasma indutivamente acoplado) para determinar a concentração de metais. As correlações entre as concentrações de PM10 e de metais foram avaliadas, considerando os dados meteorológicos para cada ponto de coleta e origem das massas de ar. Os resultados mostraram que as concentrações médias de PM10 foram de 36 micrograma m-3 na área rural, 50 micrograma m-3 na área urbana e 74 micrograma m-3 na área industrial. A concentração de PM10 medida na área industrial ultrapassou, em geral, o limite estabelecido pela resolução CONAMA, de 50 micrograma m-3. O teor de metais apresentou maior concentração na área industrial, sendo predominantes ferro, zinco, alumínio, titânio, manganês, cromo, níquel, cádmio e chumbo. Na área de maior tráfego, foi detectada a maior concentração de cobre e vanádio. As espécies iônicas foram maiores na área urbana, devido à proximidade do oceano. Na área rural, menores concentrações de espécies antropogênicas, como sulfato, nitrato e alguns metais (Pb, Cr, V e Ni) foram medidas. Assim, as concentrações das espécies estudadas são influenciadas pelas características locais. Porém, também foi observado a influencia do transporte de poluentes de longa distância, como queimadas e poeiras dos desertos do continente africano. Os percentuais dos extratos ácido/aquoso demonstraram que os metais extraídos de forma mais eficiente foram V e Ni (maior que 45 porcento), enquanto que os menos extraídos foram Al e Fe (menor que 3 porcento), conforme o esperado. A fração aquosa é importante para avaliar a biodisponibilidade de metais associados a danos à saúde. / [en] The scope of this study was to measure the concentration of metals and organic and inorganic anions in aqueous and acid extracts of PM10 samples collected in urban, industrial and rural zones of Rio de Janeiro. PM10 concentration was determined by gravimetric analysis and the organic and inorganic species in the aqueous extracts were determined by ion chromatography and total organic carbon (TOC). The aqueous and acid extracts were analyzed by inductively coupled plasma mass spectrometry (ICP-MS) and by ICP OES (inductively coupled plasma optical emission spectrometry), in order to determine metal content. Correlations between PM10 and metal concentrations were evaluated, considering meteorological data for each site. Results showed that the average PM10 concentrations were 36 microgram m-3; 50 microgram m-3 and 74 microgram m-3 at the rural, downtown and industrial sites, respectively. The measured PM10 concentration in the industrial site exceeded the limit allowed by the Brazilian law, which is 50 microgram m-3. While industrial area had the highest concentrations of metals, such as Fe, Zn, Al, Ti, Mn, Cr, Ni, Cd and Pb, the highest concentrations of Cu and V were found in areas with higher traffic densities. Ionic species had higher concentrations in the urban site due to the proximity to the ocean. The lowest concentrations of species from anthropogenic sources, such as sulfate, nitrate and some metals (Pb, Cr, V and Ni) were measured in the rural area. Hence, studied species concentrations are influenced by site locations, but the influence by the transportation of long distance pollutants, such as biomass burning and dust from African deserts was also observed. The acid/aqueous percentiles showed that the most efficiently extracted metals in the aqueous phase were V and Ni (greater than 45 percent) while the less efficiently extracted were Al and Fe (less than 3 percent), as expected. The aqueous fraction is important to evaluate the bioavailability of metals that are associated to damage to the human health.

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