Spelling suggestions: "subject:"0nvironmental chemistry."" "subject:"byenvironmental chemistry.""
151 |
Avaliação dos processos oxidativos UV/H2O2 e UV/PAA na degradação de matéria orgânica natural e 2-MIB/geosmina em água de abastecimentoSouza, Fernanda Scuissiatto Mares de 26 October 2012 (has links)
O cloro é o agente desinfetante e oxidante mais utilizado no mundo em sistemas de tratamento de água. Entretanto, a aplicação de cloro em águas superdiciais pode levar a formação de subprodutos de desinfecção, além da ineficiência do oxidante na degradação de micropoluentes. Este trabalho teve como objetivo avaliar a eficiência dos agentes peroxidados, peróxido de hidrogênio (H2)2) e ácidoperacético (PAA), em processo oxidativo avançado (POA) Assistido por UVC, na degradação de matéria orgânica natural e 2-MIB e geosmina em água de abastecimento. A matriz utilizada foi água do Rio Iratí, amostra na região metropolitana de Curitiba/PR. Como pré-tratamento da água, foram abordadas as etapas de coagulação, floculação, sedimentação e filtração com o agente coagulante PAC. Os POAs doram realizados em reatores UVC com lâmpadas de baixa pressão, em modo batelada e modo contímuo. No tratamento UV/H2O2, eficiência máxima de redução nos valores de UVA254 (92%) e fluorescência (95%), foram obtidas em modo contínuo após 15 minutos reacionais e 15 mg.L-¹ de H2)2, na ausência de 2-MIB/geosmina. A formação de TTHM foi reduzida, situando-se em 15,7 ÞL-¹ . A degradação dos contaminantes 2-MIB e geosmina, após prétratamento e processo UV/H2O2, resultou em teores à 0,1 þg.L-¹. A presença do solvente metanol nos contaminantes-padrão foi considerada como fator interferente negativo ao processo UV/H2O2. No tratamento UV/PAA, verificou-se a contribuição negativa de CODNP inerente ao próprio oxidante. No entanto o processo foi eficiente em até 89% na redução de intensidade de fluorescência, com formação de 21,5 þg.L-¹ de TTHM. A análise experimental indicou efeito positivo e significativo para a variável tempo de resistência em todos os ensaios e POAs realizados. Em nenhum dos ensaios foi possível obter a mineralização total do conteúdo carbônico presente nas amostragens. Os tratamentos UV/H2O2 e UV?PAA apresentaram um perfil de resposta não-linear, sendo necessários ajustes para o enquadramento em modelo quadrático. / As a disinfectant and an oxidizing agent, chlorine is the most used chemical in various water may lead the formation of desinfection byproducts, furthermore, the inefficiency on micropollutants degradation. the main purpose of this work is to evaluate the efficiency of hydrogen peroxide (H2O2) and peracetic acid (PAA), in advanced oxidation process under UVC radiation, on degradation of natural organic matter and contaminats 2-MIB/geosmin in supplying water. The environmental matrix involved was water from Iratí River, located near Curitiba/PR. Waterpretreatment included coagulation, floculation and sedimentation operations at jar test equipement, with PAC as coagulant agent. Advanced oxidative treatments were executed at UV reactors, with low-pressure lamps, in batch and continuous mode. in UV?H@O@ treatment, maximum efficiency on UVA254 reduction (92%) and fluorescence (95%), was obtained in continuos flowing mode, after 15 minutes (reaction taime) and 15 mg.L-¹ of hydrogen peroxide, in the absence of 2-MIB and geosmin. The formation of total trihalomethanes was one of the lowest at 15.7 þg.L-¹. Degradation of pollutants 2-MIB and geosmin, after pretreatment and AOP UV/H2O2, ended in concentrations lower than 0.1 þg.L-1. According to these UV/H2O2 tests, certain reduction was obsorved at efficiency results of all response factors monitored, since the presence of methanol intrinsic to the contaminat standard solution applied. In UV/PAA, was noticed some contribution of NPDOC provided by the own oxidizing agent (PAA). However, UV/PAA treatment was efficient at 89% according to fluorescence intensity reduction, associated with the formation of total trihalomethanes at 21,5 þg.L-¹. Experimental analysis indicated positive and significant effect for the variable retention time in all tests. None of the tests resulted in carbon complete mineralization. Treatment with UV/H2O2 and Uv/PAA presented non-linear response profile, being necessary adjustments for quadratic fitting.
|
152 |
Avaliação dos processos oxidativos UV/H2O2 e UV/PAA na degradação de matéria orgânica natural e 2-MIB/geosmina em água de abastecimentoSouza, Fernanda Scuissiatto Mares de 26 October 2012 (has links)
O cloro é o agente desinfetante e oxidante mais utilizado no mundo em sistemas de tratamento de água. Entretanto, a aplicação de cloro em águas superdiciais pode levar a formação de subprodutos de desinfecção, além da ineficiência do oxidante na degradação de micropoluentes. Este trabalho teve como objetivo avaliar a eficiência dos agentes peroxidados, peróxido de hidrogênio (H2)2) e ácidoperacético (PAA), em processo oxidativo avançado (POA) Assistido por UVC, na degradação de matéria orgânica natural e 2-MIB e geosmina em água de abastecimento. A matriz utilizada foi água do Rio Iratí, amostra na região metropolitana de Curitiba/PR. Como pré-tratamento da água, foram abordadas as etapas de coagulação, floculação, sedimentação e filtração com o agente coagulante PAC. Os POAs doram realizados em reatores UVC com lâmpadas de baixa pressão, em modo batelada e modo contímuo. No tratamento UV/H2O2, eficiência máxima de redução nos valores de UVA254 (92%) e fluorescência (95%), foram obtidas em modo contínuo após 15 minutos reacionais e 15 mg.L-¹ de H2)2, na ausência de 2-MIB/geosmina. A formação de TTHM foi reduzida, situando-se em 15,7 ÞL-¹ . A degradação dos contaminantes 2-MIB e geosmina, após prétratamento e processo UV/H2O2, resultou em teores à 0,1 þg.L-¹. A presença do solvente metanol nos contaminantes-padrão foi considerada como fator interferente negativo ao processo UV/H2O2. No tratamento UV/PAA, verificou-se a contribuição negativa de CODNP inerente ao próprio oxidante. No entanto o processo foi eficiente em até 89% na redução de intensidade de fluorescência, com formação de 21,5 þg.L-¹ de TTHM. A análise experimental indicou efeito positivo e significativo para a variável tempo de resistência em todos os ensaios e POAs realizados. Em nenhum dos ensaios foi possível obter a mineralização total do conteúdo carbônico presente nas amostragens. Os tratamentos UV/H2O2 e UV?PAA apresentaram um perfil de resposta não-linear, sendo necessários ajustes para o enquadramento em modelo quadrático. / As a disinfectant and an oxidizing agent, chlorine is the most used chemical in various water may lead the formation of desinfection byproducts, furthermore, the inefficiency on micropollutants degradation. the main purpose of this work is to evaluate the efficiency of hydrogen peroxide (H2O2) and peracetic acid (PAA), in advanced oxidation process under UVC radiation, on degradation of natural organic matter and contaminats 2-MIB/geosmin in supplying water. The environmental matrix involved was water from Iratí River, located near Curitiba/PR. Waterpretreatment included coagulation, floculation and sedimentation operations at jar test equipement, with PAC as coagulant agent. Advanced oxidative treatments were executed at UV reactors, with low-pressure lamps, in batch and continuous mode. in UV?H@O@ treatment, maximum efficiency on UVA254 reduction (92%) and fluorescence (95%), was obtained in continuos flowing mode, after 15 minutes (reaction taime) and 15 mg.L-¹ of hydrogen peroxide, in the absence of 2-MIB and geosmin. The formation of total trihalomethanes was one of the lowest at 15.7 þg.L-¹. Degradation of pollutants 2-MIB and geosmin, after pretreatment and AOP UV/H2O2, ended in concentrations lower than 0.1 þg.L-1. According to these UV/H2O2 tests, certain reduction was obsorved at efficiency results of all response factors monitored, since the presence of methanol intrinsic to the contaminat standard solution applied. In UV/PAA, was noticed some contribution of NPDOC provided by the own oxidizing agent (PAA). However, UV/PAA treatment was efficient at 89% according to fluorescence intensity reduction, associated with the formation of total trihalomethanes at 21,5 þg.L-¹. Experimental analysis indicated positive and significant effect for the variable retention time in all tests. None of the tests resulted in carbon complete mineralization. Treatment with UV/H2O2 and Uv/PAA presented non-linear response profile, being necessary adjustments for quadratic fitting.
|
153 |
Bioacessibilidade de chumbo de solos e rejeitos de beneficiamento de minerio e sua imobilização como fosfatos / Lead bioaccessibility in soils and wastes from smelting activities and phosphate immobilizationBosso, Sergio Tagliaferri 31 January 2007 (has links)
Orientador: Jacinta Enzweiler / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Geociencias / Made available in DSpace on 2018-08-08T10:56:41Z (GMT). No. of bitstreams: 1
Bosso_SergioTagliaferri_D.pdf: 3507482 bytes, checksum: 382e63843f28e5d40450a8a59a249945 (MD5)
Previous issue date: 2007 / Resumo: Os 50 anos de extração e beneficiamento de minérios de chumbo, em Adrianópolis (PR), geraram uma grande quantidade de rejeitos, parte dos quais ainda se encontra disposta nas imediações da refinaria que existia na localidade. Solos da área acumularam chumbo e apresentam concentrações anômalas deste elemento. A ingestão acidental de solos contaminados por chumbo, e de poeiras deles derivadas, é considerada a principal rota para a absorção de Pb, especialmente para crianças, que têm mais contato com solos e também por características do seu organismo, são mais suscetíveis que adultos aos efeitos adversos do chumbo. Em outros estudos, realizados com a população local, um número significativo de crianças e adultos apresentou concentrações de Pb no sangue acima dos valores recomendados, porém a rota de absorção não foi estabelecida. Sabe-se que a biodisponibilidade depende das fases em que o Pb se encontra e não apenas da sua concentração total, e que a fração bioacessível, isto é, solúvel em condições gastro-intestinais, permite inferir sobre os riscos que os materiais apresentam. Neste trabalho, oito amostras de solos ([Pb]= 0,04 ? 4,1% m/m) e quatro de rejeitos ([Pb]= 1,2 - 15 % m/m) da área foram usadas para estimar a bioacessibilidade do Pb em pH=1,5 (estômago) e pH=7 (intestino). Em três testes diferentes, o Pb de todas amostras de solos e de três rejeitos apresentou elevada solubilidade (5090%) nas soluções de simulação gástrica e bem menor (2-22%) nas de simulação intestinal. Nas amostras de solos, nenhuma fase de Pb foi identificada por difração de raios X, mas nos rejeitos havia óxidos de Pb, cerussita e lanarkita, que se caracterizam pela solubilidade em meio ácido, mas a presença de outras fases não pode ser descartada. As mesmas fases foram observadas por microscopia eletrônica de varredura (MEV), tanto nos solos como nos rejeitos. O Pb de uma das amostras de rejeito é menos solúvel (~ 20% em meio ácido) e nela foram identificados, entre outras fases, plumbogumita e plumbojarosita, que são menos solúveis. Amostras de dois solos e dois rejeitos foram colocados em contato com três materiais fosfatados (dihidrogenofosfato de sódio, superfosfato e rocha fosfática), com o objetivo de transformar as fases de Pb mais solúveis em fosfatos de Pb, que são menos solúveis. A bioacessiblidade do Pb após tratamentos por 1, 3 e 6 meses foi reduzida em 90% em pH ácido. Na análise elementar dos produtos formados, realizada no MEV, foi possível identificar a associação de Pb com P em vários grãos, principalmente nos rejeitos com maior teor de Pb. Estes resultados indicam que a aplicação direta de compostos fosfatados aos solos contaminados pode ser uma alternativa para diminuir a biodisponibilidade do Pb nesses materiais. / Abstract: The extraction and refining of lead ores in Adrianópolis (Paraná state, Brazil) for approximately 50 years produced a large amount of wastes, from which part is disposed nearby the former plant. As a consequence of lead processing, Pb has accumulated in soils of the area, which present anomalous concentrations of this element. The incidental ingestion of lead contaminated soils, and derived dusts, is considered as the main route for Pb absorption, specially for children, because they usually have more contact with soils and due to characteristics of their organisms, they are more susceptible to the adverse effects of Pb than adults. In other studies with local population, it was shown that a significant number of children and adults had Pb blood levels above recommended values. It is known that bioavailability depends on Pb speciation rather than just on total concentration, and that the risks presented by the materials can be inferred measuring bioaccessible fraction, i.e., soluble in gastric-intestinal conditions. In this work, eight samples of soils ([Pb]= 0.04 ? 4.1% m/m) and four of wastes ([Pb]= 1.2 - 15 % m/m) from the area were used to estimate bioaccessibility of Pb in pH=1,5 (stomach) e pH=7 (intestine). In three different tests, lead form all soil samples and from three wastes presented high solubility (50-90%) in gastric condition and much lower (2-22%) for intestinal conditions. None Pb phase was identified by X-ray diffraction in soil samples, but wastes contain were Pb oxides, cerussite and lanarkite, which are characterized by solubility in acid media, but the presence of other phases cannot be precluded. The same phases were observed by scanning electron microscopy (SEM) in soils and in wastes. One waste had less soluble Pb (~ 20% in acid pH). In this sample, among other phases, plumbogummite e plumbojarosite, which are les soluble, were identified. Two of the soils and of the wastes were put in contact with three phosphatic materials (sodium dihydrogen phosphate, super phosphate and phosphatic rock), to transform the more soluble Pb phases into Pbphosphates, which are less soluble. The bioaccessible fraction of Pb in the products, measured after 1, 3 and 6 months of treatment, was reduced in up to 90% in acidic pH. With elemental analysis of the products, by EDS-SEM, association between Pb and P was observed in several grains, specially in wastes with higher lead content. Theses results suggest that the direct application of phosphatic compounds on the contaminated soils could decrease the Pb bioavailability of these materials. / Doutorado / Metalogenese / Doutor em Geociências
|
154 |
Determinação de traços de dióxido de enxofre e sulfeto inorgânico no meio ambiente por titulação biamperométrica / Determination of trace amounts of sulfur dioxide and inorganic sulfide in the environment by biamperometric titrationJose Pedro Serra Valente 29 November 1983 (has links)
A titulação biamperométrica mostra possibilidades mais amplas que as relatadas em livros-texto, podendo-se analisar traços com elevadas precisão e exatidão. Duas aplicações foram demonstradas no presente trabalho: as determinações de SO2 e S-- inorgânico em efluentes, com enormes vantagens sobre os respectivos métodos espectrofotométricos. Em poucos minutos pode-se determinar 13 ppb de SO2 (recolhidos em TCM) com precisão de 7,7% e de 10 ppb de H2S (após separação do efluente) com precisão de 8,1%. Foram efetuadas anâlises de amostras naturais gentilmente cedidas pela CETESB e confrontadas com os métodos de referência, encontrando-se perfeita concordância nos resultados. / The biamperometric titration as studied, shows wider possibilities than classical interpretation reported in the text-books. This technique studied in this thesis shows tremendous applications in trace analysis, with higer accuracy and precision. In the present thesis, two applications of The technique were made: the determinations of SO2 in the atmosphere and inorganic S-- in waters, with advantages over the respective spectrophotometric methods. In few minutes one can determine 13 ppb the SO2 (absorved in TCM) with 7,7% accuracy and 10 ppb the S-- (after recovery in ZnAc2) with 8,1% accuracy. Natural samples offered by CETESB (Environmental Protection Agency of the State of São Paulo) and the results found were in good agreement with those obtained by the reference methods.
|
155 |
Procedimentos analíticos em determinações multi elementares de particulados do aerossol atmosférico para uso em modelo receptor / Analytical procedures in multi elemental determinations of particles of atmospheric aerosol for use in receiver modelElizabeth Sonoda Keiko Dantas 10 May 1999 (has links)
O monitoramento da poluição ambiental requer técnicas analíticas confiáveis e efetivas para analisar diferentes níveis de concentração de elementos metálicos. Com este objetivo, foi desenvolvido um método analítico para a determinação de metais presentes (Cd, Co e Cr) no particulado atmosférico, coletados em filtros de celulose, com a introdução direta da amostra sólida utilizando a espectrometria de absorção atômica com forno de grafite (GFAAS). As amostras foram cortadas utilizando um cortador de aço inoxidável com 2 mm de diâmetro e introduzidas no tubo de grafite por meio de pinça de aço inoxidável. Foi investigada a influência do pré - tratamento térmico do tubo com o modificador de matriz Pd/Mg no sinal de absorbância de alguns elementos como Cd, Pb, Sn, Se, Sb, Cr e Co. A calibração foi feita com curva analítica construída com soluções padrão. Concluiu-se que é possível determinar Cd e Co diretamente nas amostras de filtro de celulose com a introdução direta da amostra no forno de grafite. O Cr apresentou interferência, provavelmente do branco, na sua determinação direta por GFAAS. Uma combinação de métodos analíticos diferentes como ICP-AES (espectrometria de emissão atômica com fonte de plasma de argônio induzido); IC (cromatografia de íons), XRFS (espectrometria de fluorescência de Raios X), INAA (análise por ativação neutrônica instrumental) e PIXE (emissão de Raios X induzidos por partícula) foi utilizada para formar um banco de dados para utilização em modelo receptor e intercomparação dos resultados. A Análise de Componentes Principais (APC) foi aplicada para identificar as fontes poluidoras. Foram identificadas quatro fontes: o primeiro fator (Cd, Cu, K, Pb, Se, Sn, Sb) está associado às contribuições industriais (incluindo fundições) e incineradores municipais. O segundo fator com altos pesos para Al, Ca, Co, Fe, S, e também para Na+, NO3- e NH4+ pode ser associado à ressuspensão de partículas do solo e emissão biogênica. O terceiro fator (Cl- e As) pode estar associado a processos a altas temperaturas (indústria) e o quarto fator (SO4=) às emissões de uma fábrica de ácido sulfúrico existente nas imediações ou reações fotoquímicas do S e seus compostos. / Environmental monitoring requires reliable and effective analytical techniques for different concentration ranges. With this aim, an analytical method was developed for direct analysis of atmospheric particulate solid samples using graphite furnace atomic absorption spectrometry (GFAAS) to determine metalic elements (Cd, Co and Cr). The filters were subsampled using clean stainless steel punch (2 mm diameter) and this disc was inserted directly into the graphite tube using a stainless steel tweezer. It was also investigated the influence of the thermal pretreatment of Pd/Mg modifier in the absorbance signal of some elements such as Cd, Pb, As, Se, Sb, Cr and Co. A combination of different analytical methods like ICP-AES (Inductively Coupled Plasma - Atomic Emission Spectrometry); IC (Ion Chromatography), XRFS (X Ray Fluorescence Spectrometry), INAA (Instrumental Neutron Activation Analysis) and PIXE (Particle Induced X Ray Emission) were used to find the requeriments for receptor model analysis and intercomparison of the results. Principal Component Analysis (PCA) was applied to identify the particles sources. Four sources were identified: the first factor (Cd, Cu, K, Pb, Se, Sn, Sb) is associated to industrial emission and garbage burning. The second factor with high values to Al, Ca, Co, Fe, S, and also to Na+, NO3- e NH4+can be associated with resuspended soil dust and biogenic emission. The third factor (Cl- and As) is associated to high temperature process and the fourth factor (SO4=) to sulphuric acid emission from a factory near the sampling point or to photochemical reactions of S and their compounds.
|
156 |
Determinação de íons fluoreto em águas, por titulação condutométrica com nitrato de Lantânio (III) / Determination of fluoride ions in water by conductometric titration in Lanthanum nitrate (III)Joao Carlos Alves 28 November 1986 (has links)
Fluoreto presente em águas de abastecimento, pode ser determinado por titulação condutométrica, usando-se La(NO3)3 como titulante. O método proposto no presente trabalho exige a separação prévia de fluoreto da amostra, por destilação a 135ºC. O pH do destilado é ajustado entre 5,5 - 6,0; etanol é adicionado até atingir-se a proporção de 50%, titulando-se a solução resultante com La(NO3)3. Nessas soluções, fluoreto nas concentrações de 500 ppb e 2,0 ppm podem ser determinadas com precisões de 5% e 4%, respectivamente. Amostras naturais foram analisadas condutometricamente pelo método proposto, potenciometricamente com eletrodo íon seletivo de fluoreto, obtendo-se resultados compatíveis. / Fluoride ions in drinking water can be easily determined by condutometric titraction using La(NO3)3 as titrant. The sample must be destilled in H2S04 previously to separate the fluoride ions, at 1350 C. The destillated, in 50% ethanol is titrated with La(NO3)3 In these conditions, fluoride ions at the concentrations of 500 ppb and 2,0 ppm are determined with accuracy of, respectively, 5% and 4%. Natural samples of drinking water were analysed by this method and by the ion-selective method, with agreement among the results.
|
157 |
The concentration and speciation of sugars in natural watersSweet, Minoo Shakerin 01 January 1979 (has links)
Due to the importance of carbohydrates in biological systems, many efforts have been made to develop a quantitative method for analysis of carbohydrates in natural waters. The low concentrations of dissolved sugars in natural waters require a sensitive analytical method. In this study, gas chromatography of alditol acetate derivatives of sugars was investigated for quantitative and qualitative analysis of individual dissolved sugars in natural waters. The alditol acetate derivatives of sugars give only one derivative for each sugar, yielding qualitative and quantitative results.
The detection limit was 25 nM for each sugar. Because of this very low detection limit, only 100 ml of sample was required for analysis.
From measurements of the alditol acetate derivatives, qualitative and quantitative analysis of pentoses (arabinose and xylose) and hexoses (mannose, galactose, and glucose) were obtained from The Williamson River and its tributaries, which are located near Klamath Falls, Oregon. Total organic carbon concentrations vary greatly in this river system as a result of the river passing through Klamath Marsh, which introduces very high amounts of humic substances into the river system.
The range of total concentrations of dissolved sugars is 0.07 to 7.3 μM; the lowest occurring in the spring waters, and the highest in humic-rich waters.
Monosaccharide, polysaccharide, and humic-bonded saccharide concentrations, which were obtained from three sample sites, showed very low concentrations of monosaccharides, moderate concentrations of polysaccharides, and moderately high concentrations of humic-bonded saccharides.
|
158 |
Reaction of aqueous catechol solutions with mineralsPoocharoen, Boonthong 01 January 1972 (has links)
The effectiveness of catechol, an aromatic vic-diol, in dissolving silicate minerals was studied. A synthetic amorphous magnesium trisilicate, Mg₂Si₃O₈∙5H₂O, as well as the minerals olivine, sepiolite, diopside, augite, and enstatite were used to react with catechol in slightly acidic, basic, and neutral solutions. It was found, depending on the solvent used, that 33-52, 8-17, 14-30, 5-11, 3-6, and 0.5-1 % of the minerals dissolved, respectively.
The reaction with Mg₂Si₃0₈·5H₂0 resulted in the formation of crystals of magnesium tris (catecholato) siliconate nonahydrate Mg[Si(Cat)₃]∙9H₂0. Dehydration of the crystals at room temperature resulted in the loss of 6 moles of water to form a trihydrated complex, Mg[Si(Cat)₃]·3H₂0; further dehydration at 100°C gave an anhydrous complex, Mg[Si(Cat)₃]. By adding guanidine hydrochloride, CN₃H₆Cl, to the reaction mixture after filtering, crystals of guanidinium tris (catecholato) siliconate monohydrate, (CN₃H₆)₂[Si(Cat)₃]∙H₂0, were obtained. Infrared and nmr spectra, and analytical and x-ray powder diffraction data are presented. The possible structures of the magnesium salts of tris (catecholato) siliconate are also discussed.
The reaction of catechol with the minerals listed above gave a water soluble silicon-catechol complex, Si (Cat)₃⁼, which was isolated as (CN₃H₆)₂[Si(Cat)₃]·H₂0 by adding guanidine hydrochloride to the reaction mixture after filtering. The dissolution of these minerals by catechol to form Si(Cat)₃⁼ leads to the conclusion that aromatic vic-diols in nature may play a role in chemical weathering, in transport of silicon into rivers or seas, in soil development, in interconversion of minerals, and in accumulation of silica in plants.
|
159 |
Unrefined Humic Substances as a Potential Low-cost Remediation Method for Groundwater Contaminated with Uranium in Acidic ConditionsGonzalez Raymat, Hansell 25 October 2018 (has links)
Anthropogenic activities such as uranium mining and milling, nuclear weapons production, and nuclear reprocessing have left a legacy of groundwater and soil contaminated with uranium that needs to be addressed. Therefore, developing new remediation technologies to sequester uranium in situ is crucial. The objective of the study was to determine if low-cost commercially available unrefined humic substances, such as Huma-K, can be used to facilitate uranium sorption to minerals in soil and sediment. Sediments from the saturated zone beneath the F-Area seepage basins at the Savannah River Site (SRS) in South Carolina were used for the present study. The SRS site is analogous to many contaminated locations where groundwater acidity enhances uranium and other contaminants mobility.
First, a variety of techniques were applied to characterize Huma-K and SRS sediment. Characterization studies showed that Huma-K possesses functional groups that have an acidic nature such as carboxyl and phenol groups. For SRS sediment, a mineral composition of mainly quartz (93.2%), kaolinite (5.1%), and goethite (1.1%) was identified.
Second, the interactions between Huma-K and SRS sediment were investigated through batch experiments. Sorption, homogeneous precipitation, and surfaced-induced precipitation were observed to be enhanced at pH 4. However, Huma-K removal from solution decreased with an increase of pH. The sorption behavior was not able to be described by any of the models employed (pseudo-first, pseudo-second, Langmuir, and Freundlich).
Third, the interactions between uranium and SRS sediment with and without Huma-K amendment were investigated. In acidic conditions (pH 3-5), the sorption capacity of SRS sediment amended with Huma-K was significantly increased compared to plain sediment. At circumneutral conditions, uranium removal from solution decreased for SRS sediment amended with Huma-K, compared with plain sediments, likely as a result of the formation of aqueous uranium-humic complexes. In summary, the results from the present study suggest that Huma-K, and likely other unrefined humate products, has the characteristics and effects necessary to be suitable for subsurface injection to remediate uranium in acidic groundwater conditions. The treatment zone will persist as long as the pH does not increase sufficiently to cause soil-bound Huma-K to be released, remobilizing uranium.
|
160 |
CHARACTERIZATION OF NAPHTHENIC ACID FRACTION COMPOUNDS IN AN OIL SANDS PIT LAKE USING ULTRA-HIGH RESOLUTION MASS SPECTROMETRY WITH ELECTROSPRAY IONIZATIONBothen, Jacob January 2023 (has links)
Extraction and production of viscous petroleum or bitumen in Alberta, Canada has rapidly developed in the last 30 years, and in 2022 the average daily production was nearly 4 million barrels/day. As a result of the increased global demand of crude oil and technical improvements in the extraction process of surface mining and in situ technologies, this daily output of crude oil is expected to increase further. Surface mining operations are required to invest and implement long-term reclamation strategies in order to properly reduce/manage the large volumes of oil sands process-affected water (OSPW) and tailings and convert the surrounding mining area into an environment similar to its initial state. Commissioned in late 2012 within Syncrude’s Mildred Lake mining site is Base Mine Lake (BML), the first full-scale demonstration of Water Capped Tailings Technology. This aquatic reclamation environment serves as the first of many oil sands pit lakes proposed in the surrounding region, therefore, it is crucial that a comprehensive assembly of scientific pursuits are incorporated into the monitoring and research programs of BML. The presence of petroleum-associated organic compounds, such as Hydrocarbons and Naphthenic acid Fraction compounds (NAFC), remains a top priority for evaluating how BML meets surface water guidelines, but also plays a larger role in the scientific understanding of how biogeochemical and physical processes can impact the environmental fate and transport of these organic compounds in future oil sand pit lakes.
This master’s dissertation is focused on the use of ultra-high resolution mass spectrometry to determine the molecular profile of NAFCs extracted from BML in 2019. In this thesis, electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FT ICR MS) was used to investigate: i) how particular experimental variables impact the qualitative measurements of oil sand NAFCs, and ii) the spatial variability of NAFCs within the BML water cap and FFT with the aim of providing novel insights to key biogeochemical processes and potential transport mechanisms for continued NAFC inputs in the water column. / Thesis / Master of Science (MSc)
|
Page generated in 0.1069 seconds