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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.
101

Contaminant issues in production and application of biochar

Buss, Wolfram January 2016 (has links)
For widespread use of biochar in agriculture and horticulture, it must be ensured that application will neither adversely affect soil and plants, nor exceed legislated contaminant concentrations. The most relevant groups of contaminants in biochar are potentially toxic elements (PTEs), polycyclic aromatic hydrocarbons (PAHs) and volatile organic compounds (VOC). In this thesis, the concentrations of these groups of contaminants were analysed in 90 different biochars produced by slow pyrolysis. Subsequently, the concentrations were compared to legislation/guideline threshold values and linked to production conditions. The risk these contaminants pose to plant growth was also assessed, to give recommendations on production of safe biochar. PTEs can neither be formed nor destroyed, which means their presence in biochar is predominantly determined by feedstock type. However, significant levels of Cr, Fe and Ni were introduced into biochar from the furnace steel, whilst PTEs with low boiling points, such as As, Cd and Zn, partially evaporated during pyrolysis. PTEs were not responsible for phytotoxic effects observed for PTE-rich biochars despite biochar’s exceedance of available and total PTE threshold values for soil and soil amendments. Although initial tests were promising, the risk that PTE-rich biochars as amendment for soil and growing media pose, needs further investigation. The PAH concentration in biochar was markedly reduced by increasing carrier gas flow rate, and the type of feedstock also influenced the PAH content. However, there was no clear dependence of pyrolysis temperature on PAH concentrations, which was attributed to PAHs being increasingly formed and evaporated at higher pyrolysis temperatures. Ultimately, condensation of pyrolysis vapours and deposition on biochar was identified as the main risk for biochar contamination with PAHs, as this resulted in elevated concentrations of high-risk, higher molecular weight PAHs. Weaknesses in the pyrolysis unit design, such as cold zones, resulted in elevated concentrations of VOCs, as well as PAHs, in biochar. Comparing concentrations and phytotoxic potential of both compound groups, it was concluded that observed toxic effects were much more likely caused by VOCs in biochars containing both contaminants. Overall, formation of VOCs and PAHs cannot be prevented, but their presence in biochar resulting from retention and deposition can be minimised.
102

Forced Overexpression of Translationally Controlled Tumor Protein (TCTP/TPT1) Induces a Growth-Dysregulated Phenotype in Endothelial and Smooth Muscle Cells: Role of TCTP Exosomal Export in Paracrine Cell-Cell Signaling Induced by Endothelial Injury

Hassan, Dhiya 10 January 2019 (has links)
Background: Pulmonary arterial hypertension (PAH) is a lethal disease for which the fundamental molecular mechanisms are only partially understood. Existing therapies, which primarily focus on endothelial dysfunction, have limited effects on improving outcomes. Increases in pulmonary vascular resistance in PAH may be attributed to complex lung arterial remodeling which result in obliterative “plexiform” lesions, a pathological hallmark of this disease. Recent studies have shown that endothelial cell (ECs) apoptosis may be a central trigger for PAH, resulting in the emergence of growth-dysregulated and apoptosis-resistant ECs that contribute to the formation of complex neoplastic-like vascular lesions. However, the mechanism which links ECs apoptosis to dysregulated growth is not yet known. Previous studies in our lab have identified increased expression of translationally controlled tumor protein (TCTP) and its gene (TPT1), previously implicated in the transformation of neoplastic cells in cancer, and in blood outgrowth ECs from patients with PAH. Moreover, TCTP expression was found to be elevated in the lungs of patients with PAH, and tightly localized to complex arterial lesions. In addition, it was detected in obliterative intimal lesions of an experimental rat model of severe PAH. Hypothesis: TCTP represents a central molecular mechanism linking ECs apoptosis to the emergence of growth-dysregulated lung vascular cells and occlusive, complex arterial remodelling in PAH. Specific Hypotheses: - Lentiviral overexpression of TCTP in human umbilical vein endothelial cells (HUVECs) and pulmonary artery smooth muscle cells (PASMCs) leads to a hyperproliferative and apoptosis-resistant phenotype. - Overexpression of TCTP will increase its export into apoptotic extracellular vesicles, thereby augmenting cell-cell signalling between ECs and neighbouring SMCs. Purpose: My objective was to examine the effects TCTP overexpression on ECs and SMCs survival in terms of proliferation and apoptosis, and TCTP release on the survival of nontransduced ECs and SMCs. Methods and Results: The effect of TCTP overexpression on ECs growth and survival was studied using in vitro models. TCTP was overexpressed via a lentivirus vector in HUVECs and PASMCs. Compared to non-transfected or null transfected cells, TCTP overexpression led to increases in BrdU incorporation, consistent with hyper-proliferation, and decreases in caspase activity, consistent with apoptosis resistance. As well, TCTP was selectively exported into the conditioned media of apoptotic ECs, but not SMCs, despite similar levels of overexpression. In addition, the level of release was greater in serum starved conditioned media in comparison to the exosome fraction. Finally, our data demonstrates a selective effect of conditioned media (CM) from serum-starved ECs on PASMCs, but not ECs, in terms of an increase in proliferation and a decrease in apoptosis. Conclusions: These support the idea that TCTP overexpression confers an increase in the survival of SMCs and HUVECs. Moreover, TCTP released from apoptotic ECs leads to a growth-dysregulated phenotype within SMCs (but not ECs) and may contribute to the formation of complex lung arterial lesions, leading to arteriolar obliteration in PAH. Finally, an increase in the level of TCTP expression via lentiviral transduction led to an increased TCTP export into the media, but this appeared to be mostly in the soluble portion, and less was associated with exosomes.
103

Desenvolvimento de metodologia para avaliação de hidrocarbonetos policíclicos aromáticos e derivados em emissões de motores usando diesel/biodiesel / Development of methodology for evaluation of polycyclic aromatic hydrocarbons and derivatives in emissions from engines using diesel / biodiesel

Carina Santos Casal 26 March 2012 (has links)
Os hidrocarbonetos policíclicos aromáticos (HPA) são amplamente estudados na área de meio ambiente, em diversas matrizes ambientais como ar, água, solo e sedimento, devido a sua toxicidade, potencial mutagênico e carcinogênico. Por conta disto, as agências ambientais de países desenvolvidos listaram dezesseis HPA como sendo poluentes prioritários. As legislações a nível mundial não estipulam limites para estes compostos para ar ambiente, somente para emissões de fontes fixas e móveis e ambientes ocupacionais, mas existem diversos estudos, mais especificamente para os 16 prioritários HPA e muito pouco para os homólogos alquilados. Os HPA alquilados são mais abundantes, persistentes e frequentemente mais tóxicos que os não alquilados e a toxicidade aumenta com o número de substituições alquil sobre os núcleos aromáticos. As legislações ambientais em todo o mundo não realizam o controle em nenhuma matriz ambiental para os HPA alquilados. Neste trabalho foi desenvolvido um método para análise dos HPA e seus homólogos alquilados, utilizando cromatografia de fase gasosa acoplado a um detector de espectrometria de massa e com um sistema de injeção para grande volume, associado à vaporização com temperatura programada, que permitiu um nível de detecção na faixa de 0,70 até 103,6 ng mL-1, sendo possível analisar as amostras de material particulado oriundas de emissões veiculares. As amostras foram coletadas de acordo com a Norma ABNT NBR14489, em um dinamômetro de bancada para motor do ciclo diesel (Ciclo de 13 pontos). Os resultados encontrados foram na faixa de 0,5 ng mL-1 até 96,9 ng mL-1 Os resultados indicaram que motores a diesel/ biodiesel têm uma contribuição muito grande na formação destes HPA e homólogos alquilados
104

Desenvolvimento de eletrodos de carbono vítreo modificados com nanotubos de carbono para a determinação de analitos de interesse farmacêutico / Development of modified glassy carbon electrodes with carbon nanotubes for determination of analytes of pharmaceutical interest

Oliveira, Geiser Gabriel de 21 March 2013 (has links)
Made available in DSpace on 2016-06-02T20:34:43Z (GMT). No. of bitstreams: 1 5218.pdf: 2403909 bytes, checksum: d82fc82071edd00ee14aaa70f939364d (MD5) Previous issue date: 2013-03-21 / Universidade Federal de Sao Carlos / In this work, the development of electroanalytical methods for the determination of methotrexate (MTX), propylthiouracil (PTU), propanolol (PROP) and verapamil (VPM) in pharmaceutical formulations is described. In these methods it was employed a glassy carbon electrode (GC) modified with dihexadecyl hydrogenphosphate (DHP) or polyallylamine hydrochloride (PAH) film containing immobilized multi-walled carbon nanotubes (MWCNTs). Initially, the electrochemical behavior of each modified electrode was studied by cyclic voltammetry at different scan rates for a 1.0 × 103 mol L1 potassium hexacyanoferrate (III) in 0.1 mol L1 potassium chloride solution. Applying the Randles-Sevcik equation, it was observed an increase of the active area of MWCNTs-DHP/GC and MWCNTs-PAH/GC electrodes of 1.5 and 3.1 times respectively in comparision with the GC electrode. The square wave voltammetry, differential pulse voltammetry and linear sweep voltammetry parameters were studied and optimized for each analyte and then it was selected the best technique for the development of the analytical method. In the developed method for MTX determination in pharmaceutical formulations, it was used the GC electrode modified with MWCNTs and DHP (MWCNTs-DHP/GC), employing differential pulse adsorptive anodic stripping voltammetry (DPAdASV) technique after the optimization of experimental conditions. The analytical curve obtained was linear in the MTX concentration range from 5.0 × 10-8 to 5.0 × 10-6 mol L-1, with a limit of detection (LOD) of 1.2 × 10-8. The MTX was quantified in commercial samples and the results compared with an HPLC method, and the relative errors ranged from -4.0 to 4.0%. An analytical method for determination of PTU in pharmaceutical formulations was also developed using a modified GC electrode with MWCNTs within a PAH film (MWCNTs-PAH/GC) and linear sweep adsorptive cathodic stripping voltammetry (LSAdCSV). After the optimization of experimental conditions, the analytical curve was linear in the PTU concentration range from 5.0 × 10-6 to 5.8 × 10-5 mol L-1, with a LOD equal to 1.0 × 10-6 mol L-1. The PTU was quantified in commercial samples and the results were compared with those results obtained using the British Pharmacopoeia method. The relative errors obtained were between -1.0 and 2.0%. Using DPAdASV technique and a MWCNTs-PAH/GC electrode, PROP was determined in pharmaceutical formulations. The analytical curve was linear in the concentrations range from 7.5 × 10-8 to 1.0 × 10-6 mol L-1 PROP, with LOD equal to 6.3 × 10-8 mol L-1 and the results were in close agreement whit those obtained using the Brazilian Pharmacopoeia method at a confidence level of 95 %. The relative standard deviation ranged from 2.5 and 1.2%. Finally, as a fourth electroanalytical method, a square wave adsorptive anodic stripping voltammetry (SWAdASV) was proposed for determination of VPM in pharmaceutical formulations using a MWCNTs-PAH/GC electrode. The analytical curve was linear over the VPM concentration range 5.0 × 10-9 - 1.0 × 10-7 mol L-1, with an LOD of 3.6 × 10-9 mol L-1 . The VPM was quantified in pharmaceutical samples and the results compared with results obtained using the method of the Brazilian Pharmacopoeia. / Neste trabalho descreve-se o desenvolvimento de métodos eletroanalíticos para a determinação de metotrexato (MTX), propiltiouracil (PTU), propranolol (PROP) e verapamil (VPM) em formulações farmacêuticas. Nestes métodos foi empregado um eletrodo de carbono vítreo (GC) modificado com filme dihexadecil hidrogênofosfato (DHP) ou hidrocloreto de poli(alilamina) (PAH), contendo, imobilizados, nanotubos de carbono de paredes múltiplas (MWCNTs) tratados quimicamente. Inicialmente verificou-se o comportamento eletroquímico desses eletrodos modificados empregando-se voltametria cíclica, em diferentes velocidades de varredura, para uma solução de hexacianoferrato (III) de potássio 1,0 x 10-3 mol L-1 em cloreto de potássio 0,1 mol L-1. Aplicando-se a equação de Randles-Sevcik, observa-se um aumento da área ativa para os eletrodos MWCNTs-DHP/GC e MWCNTs-PAH/GC de 1,5 e 3,1 vezes respectivamente quando comparado com o eletrodo de GC. Os parâmetros da voltametria de onda quadrada, voltametria de pulso diferencial e voltametria linear foram estudados e otimizados para cada analito e selecionada a melhor técnica para o desenvolvimento do método analítico. No método desenvolvido para a determinação de MTX em formulações farmacêuticas, utilizouse o eletrodo de GC modificado com MWCNTs e DHP (MWCNTs-DHP/GC), empregando-se a Voltametria Adsortiva de Redissolução Anódica por Pulso Diferencial (DPAdASV), após a otimização das condições experimentais. A curva analítica obtida foi linear no intervalo de concentração de MTX de 5,0  108 a 5,0  106 mol L-1, com um limite de detecção (LD) igual a 1,2  108. O MTX foi quantificado em amostras comerciais e os resultados comparados com um método de HPLC, sendo que os erros relativos variaram de -4,0 e 4,0 %. O segundo método analítico desenvolvido foi para a determinação de PTU em formulações farmacêuticas, utilizando como eletrodo o GC modificado com MWCNTs e PAH (MWCNTs-PAH/GC). A técnica eletroanalítica selecionada foi a Voltametria Linear Adsortiva de Redissolução (LSAdCSV), após a otimização das condições experimentais. A curva analítica obtida foi linear para o PTU nas concentrações de 5,0  106 a 5,8  105 mol L-1 com LD igual a 1,0  106 mol L-1. O PTU foi quantificado em amostras comerciais, os resultados comparados com método preconizado pela Farmacopéia Britânica e os erros relativos obtidos ficaram entre 1,0 e 2,0 %. O terceiro método analítico desenvolvido foi para a determinação de PROP em formulações farmacêuticas, utilizando como eletrodo o MWCNTs- PAH/GC, sendo a técnica selecionada a DPAdASV. A curva analítica obtida foi linear no intervalo de concentração do PROP de 7,5  108 a 1,0  106 mol L-1, com LD igual a 6,3  108 mol L1.. O PROP foi quantificado em amostras comerciais e os resultados comparados com o método proposto pela Farmacopéia Brasileira. Os erros relativos obtidos ficaram entre 2,5 e 1,2 %. Na sequência, o quarto método desenvolvido foi para a determinação de VPM em formulações farmacêuticas, utilizando como eletrodo o MWCNTs-PAH/GC, sendo a técnica selecionada a voltametria de redissolução anódica de onda quadrada (SWAdASV). A curva analítica obtida foi linear no intervalo de concentrações de VPM de 5,0  109 a 1,0  107 mol L-1, com um LD igual a 3,6  109 mol L1. O VPM foi quantificado em amostras farmacêuticas e os resultados comparados com os resultados obtidos empregando o método espectrofotométrico preconizado pela Farmacopéia Brasileira.
105

Characterization of soil remediation workers’ dermal exposure to polycyclic aromatic compounds

Johansson, Beatrice January 2018 (has links)
Polycyclic aromatic hydrocarbons (PAHs) are organic compounds that are composed by at least two aromatic rings. PAHs can be found in coal and petroleum, but can also be formed from incomplete combustion of for example fossil fuels, tobacco, wood and when smoking food. PAHs has been shown to cause several health risks such as carcinogenic effects, which led to that the U.S Environmental Protection Agency (U.S. EPA) selected 16 PAHs as priority pollutants. Those 16 PAHs is usually analysed when investigating PAH exposure. To analyze dermal exposure of PAHs a tape-stripping technique can be used. The tape-stripping method involves that a tape piece is placed on the skin to absorb the present PAHs and then the tape is removed and the PAHs can be extracted and cleaned-up from the tape. The aim of this study is to optimize a recently elaborated clean-up method for PAHs sampled by the tape-stripping technique. Also, to apply the method and measure the dermal exposure of 16 PAHs among soil remediation workers. Two clean-up methods were evaluated, Florisil SPE columns and deactivated silica (10%). Clean-up using Florisil columns were evaluated using 10 and 12 ml of n-hexane. For elution, poor recoveries were achieved for both elution volumes tested. On the other hand, tests using deactivated silica generated good recoveries for both elution solvents tested (i.e. 4 ml n-hexane:dichloromethane + 4 ml dichloromethane and 8 ml n-hexane). As for the elution solvents, no significant difference could be seen in the recoveries and the mixture of n-hexane and dichloromethane was used for the real samples. The dermal exposure of PAHs for the soil remediation workers were investigated using dermal tapes from the palm and neck of 18 soil remediation workers. Samples from the palm were sampled before and after a working day and there was a small difference between the total PAH concentration before and after a work-shift. For all categories of workers (office staff, machine operators and persons performing sampling) an increase in dermal concentration of PAHs could be observed for ten of the workers, but this increase were highest among the workers active in taking samples at the contaminated site. However, an increase in PAH exposure was not observed for all study participants and possible this is due to hand-washing after toilet visits. Overall, the concentrations of PAHs on the dermal samples from soil remediation workers were low, especially in comparison to other occupations such as chimney sweeps and pavers where PAH exposure is known to exist. The detected PAHs on the dermal tapes corresponded to PAH profiles in soil samples from the site.
106

ValidaÃÃo de metodologia de determinaÃÃo de hidrocabonetos policÃclicos aromÃticos em Ãguas de produÃÃo por microextraÃÃo em fase sÃlida. / Validation of determinations methods of PAHs in produced water by solid phase microextraction

Pedro Hermano Menezes de Vasconcelos 05 April 2013 (has links)
Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / O descarte de Ãgua de produÃÃo em oceanos à um dos grandes problemas ambientais enfrentados pela indÃstria de petrÃleo e pela populaÃÃo, uma vez que esses efluentes possuem compostos nocivos à saÃde. Dentre estes compostos destacam-se os hidrocarbonetos policÃclicos aromÃticos (HPAs), compostos orgÃnicos caracterizados por apresentarem dois ou mais anÃis aromÃticos conjugados. Neste trabalho utilizou-se um planejamento fatorial para avaliar o efeito de alguns parÃmetros na extraÃÃo de HPAs em amostras de Ãgua de produÃÃo por microextraÃÃo em fase sÃlida (MEFS) e posterior anÃlise por cromatografia gasosa acoplada a um espectrÃmetro de massas (CGMS). Verificou-se que a tÃcnica favorece a prÃ-concentraÃÃo de HPAs em amostras e que os parÃmetros estudados (temperatura, concentraÃÃo de HPA, forÃa iÃnica, tempo de exposiÃÃo à fibra) influenciam de forma significante na quantidade de HPA extraÃda, sendo que o efeito de cada fator depende das estruturas dos HPAs. A anÃlise quantitativa e qualitativa por CGMS foi realizada utilizando a tÃcnica de fragmentos distintos em seus espectros de massas. Foram analisadas quatro amostras de Ãgua de produÃÃo, utilizando-se o mÃtodo de padrÃo interno. Realizou-se a validaÃÃo da metodologia, atravÃs de testes de precisÃo, linearidade, limites de detecÃÃo e quantificaÃÃo, e exatidÃo. A metodologia proposta mostrou-se eficiente visto que apresentou boa reprodutibilidade, linearidade satisfatÃria (os coeficientes de correlaÃÃo obtidos ficaram entre 0,9849 e 0,9999), valores de LD e LQ compatÃveis aos da literatura, e uma exatidÃo adequada na faixa de concentraÃÃo avaliada (valores de recuperaÃÃo variaram entre 84,23 e 148,52 %). O diferencial da metodologia foi ter conseguido analisar os HPAs presentes nas amostras que possuÃam matrizes bastante complexas sem a necessidade de qualquer prÃ-tratamento das mesmas. Os HPAs de menores massas molar foram, em geral, os majoritÃrios nas amostras de Ãguas investigadas. A quantidade total de HPA presente nas quatro amostras variou de 30,41 a 170,41 Âg L-1. Os valores das constantes de distribuiÃÃo calculados indicam que os HPAs de maiores massas molares apresentaram maior afinidade pela fibra de polidimetil-siloxano. / The disposal of water from oil production in the oceans is one of the major environmental problems facing the oil industry and the population, since these compounds have harmful effluents health. Among these compounds, the polycyclic aromatic hydrocarbons (PAHs) stand out. These substances are organic compounds characterized by presenting two or more conjugated aromatic rings. This study evaluated the effect of some parameters on the extraction of PAHs by SPME and subsequent analysis by GCMS using 24 factorial design to optimize the experiments, followed by the analysis of water samples from oil production. It has been found that the technique pre-concentrated samples and the parameters (temperature, PAH concentration, ionic strength, exposure time of the fiber) influence significantly on the amount of PAH extracted, and the effect of each factor depends on the structures of PAHs. The quantitative and qualitative analysis by GCMS was conducted using the technique of distinct fragments in their mass spectra. Four samples were analyzed for water production, using the internal standard method. Conducted to validate the methodology through testing precision, linearity, limits of detection and quantification, and accuracy. The proposed method was efficient, as it showed good reproducibility, linearity satisfactory (correlation coefficients were obtained between 0.9849 and 0.9999), values of LD and LQ compatible with the literature, and an accuracy in the proper concentration range evaluated (recovery values ranged between 84.23 and 148.52%). The factor innovative of the methodology have been able to analyze the PAHs in the samples had very complex arrays without the need for any pretreatment thereof. PAHs of lower molecular masses were, in general, the majority of water in the samples investigated. The total amount of PAH present in all four samples ranged from 30.41 to 170.41 g L-1. The values of the constants calculated distribution indicate that PAHs of higher molecular weights had higher affinity for the polydimethylsiloxane fiber.
107

Investigação sobre a emissão e caracterização dos hicrocarbonetos policiclicos aromaticos (HPA) na bacia do rio Atibaia / Investigation on emissions and characterization of polycyclic aromatic hydrocarbons (PAHs) in the Atibaia river basin

Locatelli, Marco Antonio Fernandes 29 March 2006 (has links)
Orientador: Wilson de Figueiredo Jardim / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-06T21:59:45Z (GMT). No. of bitstreams: 1 Locatelli_MarcoAntonioFernandes_M.pdf: 1462922 bytes, checksum: eff1592d31e618e67b22501e45f45f26 (MD5) Previous issue date: 2006 / Mestrado / Quimica Analitica / Mestre em Química
108

Pirólise e combustão de resíduos plásticos. / Pyrolysis and combustion of plastic wastes.

Cecília Korber Gonçalves 11 June 2007 (has links)
Dois milhões de toneladas por ano de resíduos plásticos são gerados no Brasil. Apenas 16,5% em massa deste resíduo plástico são mecanicamente reciclados, a maior parte restante é levada a aterros ou lixões. Todo este material poderia ser incinerado e, desta forma reduzir em até 90% a massa do volume aterrado, e seu conteúdo energético seria usado para gerar vapor ou energia. Esta investigação foi feita sobre os produtos de combustão incompleta emitidos da pirólise e combustão em estado estacionário do polietileno e poliestireno em um forno vertical de dois estágios, eletricamente aquecido. Separadamente, os polímeros na forma pulverizada foram pirolisados em temperatura constante de 1000°C e, depois da mistura com N2/O2, os produtos de pirólise foram queimados a 900, 1000 e 1100°C. Os testes foram conduzidos com 21% de O2 em volume no forno de oxidação. Diferentes razões de combustível e ar foram usadas no forno de combustão, pela variação da taxa de alimentação de polímero no forno de pirólise. A motivação para a combustão indireta de PE e PS foi obter a combustão nominalmente pré-misturada dos gases de pirólise com ar, assim, obtendo menores emissões dos produtos de combustão incompleta comparativamente à combustão direta do polímero sólido. Este trabalho examinou os efeitos da temperatura de combustão e a razão equivalente de ar e combustível. Os efluentes da pirólise e combustão foram analisados, e as emissões de CO, CO2, O2, hidrocarbonetos leves, hidrocarbonetos policíclicos aromáticos e materiais particulados foram mensurados. Ainda, o material particulado foi caracterizado quanto ao tamanho das partículas. Foi observado que enquanto a quantidade de gás de pirólise diminuiu com o aumento da taxa de alimentação do polímero, sua composição permaneceu praticamente independente da taxa de alimentação. As emissões de CO2 foram máximas perto da razão equivalente 1, enquanto as emissões de CO aumentaram com o aumento da razão equivalente. As emissões totais de hidrocarbonetos leves e PAH na combustão aumentaram tanto com o aumento da razão equivalente, quanto do aumento da temperatura. A maior parte do material particulado teve o tamanho menor que um micrometro. No geral, as emissões de PAH e material particulado da combustão indireta de PE e PS foram uma ordem de grandeza menor que a emissão correspondente da combustão direta e heterogênea do polímero sólido, obtida em outros trabalhos. Como a pirólise destes polímeros requer uma entrada nominal de calor mínima em relação à quantidade de calor gerada na sua combustão, a implantação desta técnica pode ser vantajosa. / Two millions tons/year of plastic wastes are generated in Brazil. Only 16.5% of this plastic waste is mechanically recycled, the rest is mostly landfilled. All these material could be incinerated, in a way to reduce by 90% the volume of landfilled waste, and use its energy content to supply energy. This investigation was conducted on pollutants emitted from steady-flow pyrolysis and combustion of polyethylene and polystyrene in a two-stage electrically-heated vertical furnace. Separately, the polymers, in pulverized form, were first pyrolyzed at constant temperature of 1000°C and subsequently their pyrolyzates were burned at 900, 1000 and 1100°C, upon mixing with air. Tests were conducted with 21% of O2 and different fuel to air equivalence ratios in the oxidizer furnace, by keeping the flow of gases and changing the feed rate of polymer in the pyrolyzer furnace. The motivation for this indirect combustion of PE and PS was to attain nominally-premixed combustion of the pyrolyzate gases with air, thereby achieving lower pollutant emissions than those from direct combustion of the solid polymer. This work examined the effects of the combustion temperature, as well as of the polymer feed rate and the resulting fuel to air equivalence ratio. The effluents of pyrolysis and combustion were analyzed for fixed gases (CO, CO2, O2), light hydrocarbons, polycyclic aromatic hydrocarbons and particulate matter. It was found that whereas the amount of pyrolysis gas decreased with increasing polymer feed rate, its composition was nearly independent of the feed rate. CO2 emissions peaked at an equivalence ratio near unity, while the CO emissions increased with increasing equivalence ratio. The total light hydrocarbon and PAH emissions of combustion increased both with increasing equivalence ratio and with temperature. The generated particulates were mostly submicronmeter in size. Overall, PAH and soot emissions from indirect burning of PE and PS were an order of magnitude lower than corresponding emissions from direct heterogeneous burning of the solid polymer, obtained elsewhere. As pyrolysis of these polymers requires a nominal heat input that amounts to a diminutive fraction of the heat released during its combustion, implementation of this technique is deemed advantageous.
109

Upptag av polycykliska aromatiska kolväten från olika kontaminerade jordar i daggmask (Eisenia Fetida)

Axdorff, Louise January 2017 (has links)
Många antropogena ämnen är toxiska och har lång halveringstid och återfinns därför lång tid efter att de hamnat i miljön. Ett exempel är polycykliska aromatiska kolväten (PAH), som bildas vid ofullständig förbränning av organiskt material och som kan förekomma i höga halter vid före detta gasverk och gamla träimpregneringsplatser där kreosotimpregnering förekommit. I marken på dessa områden kan halterna av PAH vara mycket höga, och det kan påverka markekosystemet negativt. En viktig markorganism är daggmask, som har stor betydelse i många markekosystem. Därför är det viktigt att veta om PAHer i mark är tillgängliga för upptag i mask, eftersom det kan påverka masken negativt. Dessutom skulle eventuella PAHer i mask kunna transporteras vidare i näringskedjor. Syftet med studien var därför att undersöka upptaget av polycykliska aromatiska kolväten (PAH) i Eisenia Fetida från förorenad jord. E. Fetida exponerades under två veckor för nio olika PAH-förorenade jordar som samlats in från två kreosotförorenade områden, en före detta gasverkstomt och en bangård. Sammanlagt 24 PAHer inklusive PAH16 analyserades i jord och mask med GC/MS. Resultaten visade upptag av PAHer i E. Fetida från samtliga jordprov, men upptaget varierade beroende på prov. Ett jordprov från en före detta gasverkstomt, gasverk c hade den högsta uppmätta totala bioackumuleringsfaktorn (BAF) för PAHer från respektive prov. De enskilda BAF-värdena i jorden var högre för de högmolekylära PAHerna, medan jordprov insamlade på en bangård visade på ett högre upptag i mask av de låg- och mellan molekylära PAHerna. Ett av de kreosotförorenade jordproverna, kreosot a hade det högsta enskilda BAF-värdet för PAHer, vilket var trifenylen som hade en BAF 18.Det var inget signifikant samband mellan PAH-halten i jordarna och PAH-halten i mask, vilket tyder på att upptaget i mask inte enbart beror på halten PAHer i jorden. Det var heller inget signifikant samband mellan halten organiskt material och upptaget av PAHer i E. Fetida, men resultaten tyder på att upptaget i E. Fetida beror mer på jordegenskaper som organiskt material än halterna av PAHer i jorden. Det är därför viktigt att fortsätta forska kring PAHer och biotillgänglighet i mark.
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Accumulation, transport and potential treatment of surface sediment on car parks with channel drains

Barlow, James Vincent January 2015 (has links)
Urban pollutants have been identified as a significant source of environmental pollution, posing a risk to human health, the environment, and are toxic to flora and fauna. Highways are recognised as one of the key sources of pollution, from both vehicles, and surrounding infrastructure. A number of studies have investigated accumulation of sediment and the associated pollutants on highways, and the runoff generated as a result of rainfall. Car parks share many potential contributory sources of pollutants with highways, but there is a lack of studies regarding car parks, despite them being identified as a significant percentage of urban land use. A series of experiments were undertaken in order to develop an understanding of the characteristics of car park sediment. The physical and chemical characteristics of sediment were analysed at different stages throughout the drainage system. Firstly on the sediment accumulated on car park surfaces, followed by that mobilised and transported into a channel drain during simulated rainfall events. Finally, potential treatment of pollutants within sediment in a channel was quantified. The physical and chemical characteristics of car park sediment was shown to be similar during both the accumulation (build-up) and wash-off stages, suggesting that the accumulated sediment is generally mobilised and transported to the channel drain (wash-off). Furthermore, both the physical and chemical characteristics of the sediment were shown to be similar to those found on highways, thorough the build-up and wash-off phases. Finally, potential treatment of organic pollutants (PAH) by biodegradation was demonstrated, but not comprehensively proved.

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