Дисертації з теми "Zn solid phase speciation"
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Miller, Carrie Lynn. "The role of organic matter in the dissolved phase speciation and solid phase partitioning of mercury." College Park, Md. : University of Maryland, 2006. http://hdl.handle.net/1903/3357.
Повний текст джерелаThesis research directed by: Marine-Estuarine-Environmental Sciences. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
King, Amanda Jane. "The speciation and geochemical reactivity of polycyclic aromatic hydrocarbons in marine water and sediments." Thesis, University of Sussex, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273158.
Повний текст джерелаBérillon, Laurent. "Mg- and Zn-Mediated Synthesis of Heterocycles in Solution and on the Solid Phase." Diss., lmu, 2000. http://nbn-resolving.de/urn:nbn:de:bvb:19-1954.
Повний текст джерелаJonsson, Sofi. "Unraveling the importance of solid and adsorbed phase mercury speciation for methylmercury formation, evasion and bioaccumulation." Doctoral thesis, Umeå universitet, Kemiska institutionen, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-64286.
Повний текст джерелаMonometylkvicksilver, MeHg, bildas under anoxiska förhållanden i naturliga vatten, sediment och jordar och bioackumuleras och magnifieras därefter i den akvatiska näringskedjan med negativa effekter på djur och människor som följd. Det är generellt vedertaget att utfällning av Hg och adsorption av Hg till exempelvis organiskt material och mineralytor begränsar tillgängligheten för biogeokemiska reaktioner av Hg som mobiliserats i miljön via naturliga och antropogena processer. Kunskap om betydelsen av speciationen av Hg i fasta och adsorberade faser för bildning, avgång och bioackumulering av MeHg är dock bristfällig. Denna information är kritisk för att förstå vilka processer som kontrollerar bildning och bioackumulering av MeHg samt för att kunna prediktera hur olika ekosystem kan förväntas svara på exempelvis ändrad deposition av atmosfäriskt Hg eller hur klimatförändringar kan påverka koncentrationerna av Hg i fisk. I denna avhandling har en experimentell metod utvecklades, där isotopanrikade fasta och adsorberade kemiska former av oorganiska tvåvärt Hg, Hg II används som s.k. "tracers". Denna metod användes för att bestämma MeHg bildningshasigheter i homogeniserade sediment prover samt i mesokosmsystem där förhållandena efterliknar de som förväntas i naturliga ekosystem. Från dessa drar vi slutsatsen att speciationen av HgII i fast/adsorberad fas är en viktig kontrollerande faktor som begränsar nettobildningen av MeHg. Mikrokosmexperiment visade att i första hand nyligt bildad MeHg avgick till gasfas vilket understryker betydelsen av MeHg bildningshastighet, snarare än koncentration, i sedimentet för denna process. Från mesokosmexperimenten visar vi, med kvantitativa data, att terrestra och atmosfäriska källor av HgII och MeHg är mer tillgängliga för bildning och bioackumulering av MeHg än HgII och MeHg lagrat eller bildat i sedimenten. Orsaken till detta är framförallt skillnad i speciationen av Hg i fasta/adsorberade faser. Detta innebär att bidraget från MeHg från terrestra och atmosfäriska källor till koncentrationen av Hg i fisk kan ha underskattats, samt att de negativa effekterna på MeHg exponering i områden där exempelvis klimat-förändringar förväntas leda till ökad terrest avrinning kan bli mer allvarliga än vad som tidigare predikterats. Data som presenteras i denna avhandling möjliggör modellering av Hg’s biogeokemiska cykel på en ny detaljnivå samt möjliggör säkrare prediktioner av hur olika ekosystem kan förväntas svara mot miljöförändringar eller ändrad deposition av atmosfäriskt Hg.
Till Finansiärer skall också följande läggas till: Kempe stiftelsen (SMK-2942, SMK-2745, JCK-2413).
CEYLAN, OZCAN. "ELECTROCHEMICALLY-AIDED CONTROL OF SOLID PHASE MICRO-EXTRACTION (EASPME) USING CONDUCTING POLYMER COATED FIBER." University of Cincinnati / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1069853643.
Повний текст джерелаMoberly, James Gill. "Influences of chemical speciation and solid phase partitioning on microbial toxicity single organism to in situ community response /." Thesis, Montana State University, 2010. http://etd.lib.montana.edu/etd/2010/moberly/MoberlyJ0510.pdf.
Повний текст джерелаReinoso-Maset, Estela. "Aqueous and solid phase interactions of radionuclides with organic complexing agents." Thesis, University of Plymouth, 2010. http://hdl.handle.net/10026.1/300.
Повний текст джерелаAmbushe, AA, RI McCrindle, and CME McCrindle. "Speciation of chromium in cow’s milk by solid-phase extraction/dynamic reaction cell inductively coupled plasma mass spectrometry (DRC-ICP-MS)." The Royal Society of Chemistry, 2009. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1001492.
Повний текст джерелаMacDonald, James Douglas. "The partitioning of Cd, Cu, Pb and Zn between the solid and solution phase of forest floor horizons in podzolic soils near metal smelters /." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=85575.
Повний текст джерелаWe developed a standard protocol to produce solutions that resemble lysimeter solutions from podzolic soils using air-dried samples. We hypothesized that the stabilization point of the electrical conductivity (EC) of the soil solution is indicative of the point in which soluble salts and organic material precipitated during sampling and storage are removed from the soil particle surfaces. Solutions produced by leaching the soils, once the EC of wash solutions had stabilized, were comparable to lysimeter solutions from the area where samples were collected with respect to the concentrations of divalent cations, pH, EC and dissolved organic carbon (DOC). The applicability of this procedure to trace metal partitioning in forest floors was explored. Laboratory extractions produced partition coefficients (log Kd) similar to observed lysimeter solutions ranging from 3.4 to 3.9 for Cd, 3.4 to 3.9 for Cu, 3.4 to 4.1 for Ni, 4.1 to 5.2 for Pb and 3.2 to 3.5 for Zn. According to a semi-mechanistic regression model based on observed lysimeter concentrations, the metal concentrations in solution were appropriate relative to known factors that influence metal partitioning in soils: pH, the concentrations of total metals and DOC.
While chemical characteristics of soils have been consistently observed to play important roles in the partitioning and toxicity of metals we wished to place the importance of the chemical characteristics of soil on mobility and toxicity in context. We interpreted field data that had been collected from transects established with distance from two point source emitters in Rouyn PQ, and Sudbury ON. Canada find developed equations that predict dissolved metal concentrations from total metal concentrations, soil pH, soil organic matter (SOM), and DOC contents. We integrated these equations into a simple box model that calculates changes in the concentration of metals in the organic and upper mineral horizons and includes a loop for vegetative return of metals to the forest floor.
Lopes, Aline Soriano. "Extração de especies organoestancias em sedimento por microextração em fase solida acoplada ao forno de grafite e determinação de estanho total por amostragem em suspensão." [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/248604.
Повний текст джерелаTese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica
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Resumo: Este trabalho de Tese visa acoplar a fibra, empregada em microextração em fase sólida (SPME, do inglês solid phase microextraction), ao espectrômetro de absorção atômica com forno de grafite (GF AAS, do inglês graphite furnace atomic absorption spectrometer), visando reter espécies organometálicas volatilizadas nas etapas de secagem e pirólise do GF AAS. O elemento escolhido para avaliar o acoplamento SPME-GF AAS foi o Sn. Primeiramente, a concentração total de Sn foi determinada, utilizando a amostragem em suspensão como estratégia, uma vez que na avaliação da distribuição dos compostos organoestânicos por SPME-GF AAS, a concentração total de Sn seria efetuada a partir de uma suspensão. Para a otimização do método foram avaliados os seguintes parâmetros: solução de preparo da suspensão, e efeito da temperatura de pirólise e atomização. A mistura contendo HF 10 % (v/v) e HNO3 1 % (v/v) foi escolhida para preparar a suspensão, a composição Mg(NO3)2 + NH4H2PO4 apresentou resultados apropriados para ser utilizada como modificador químico convencional, e 1000 e 2200 °C foram as temperaturas ótimas para a pirólise e a atomização, respectivamente. Devido ao efeito de matriz, foi utilizada a técnica de adição de analito para a quantificação de Sn em suspensões de sedimento marinho e de rio, em que os limites de detecção e quantificação calculados foram de 1,5-2,6 e 4,5- 7,6 µg g, respectivamente. Para avaliar o acoplamento SPME-GF AAS, visando à retenção das espécies organoestânicas (butiltricloroestanho, dibutildicloroestanho e tributilcloroestanho) foi utilizada, primeiramente, uma suspensão de sedimento. A suspensão foi sonicada e, em seguida, uma alíquota foi injetada no forno de grafite do GF AAS juntamente com o reagente de derivação (tetraetilborato de sódio - NaBEt4). A programação do forno de grafite foi aplicada e a fibra de SPME foi introduzida no atomizador. Após a retenção das espécies de interesse na fibra, a mesma foi conduzida ao cromatógrafo a gás (CG) para a separação e detecção dos analitos. Os parâmetros instrumentais do CG foram previamente estudados, visando a melhor separação das espécies de interesse. Esses estudos foram realizados utilizando o modo de extração por headspace e SPME (HS-SPME, do inglês headspace-solid phase microextraction). Em relação aos estudos envolvendo suspensões de sedimento no acoplamento proposto SPME-GF AAS, alguns parâmetros foram avaliados frente à retenção das espécies de interesse; entre eles pode-se citar o tipo de fibra, a concentração do reagente de derivação e o pH da reação. Melhores resultados foram observados para a fibra PDMS/DVB, utilizando uma concentração de 0,2 % (m/v) de NaBEt4 para a etilação das espécies de interesse, sendo a reação realizada em pH 5,0. Entretanto, baixa eficiência de retenção (< 20 %) das espécies de interesse em suspensão de sedimento, foi obtida utilizando-se o acoplamento SPME-GF AAS, quando comparada à extração por HS-SPME. Dessa forma, foi realizada uma extração das espécies de interesse das amostras de sedimento, utilizando a energia ultrassônica, anteriormente à sua aplicação no acoplamento proposto SPME-GF AAS. Nesta etapa do trabalho, a temperatura do forno de grafite e o tempo de exposição da fibra de SPME no forno de grafite foram otimizados, visando à máxima eficiência de retenção das espécies de interesse no acoplamento SPME-GF AAS. Os melhores resultados foram observados para temperaturas do forno de grafite de 90 °C, com 986 s de tempo de exposição da fibra no atomizador. Por fim, foram realizados experimentos visando determinar a concentração total de Sn, e reter suas espécies organometálicas simultaneamente, na fibra de SPME, utilizando o acoplamento SPME-GF AAS.
Abstract: The goal of this Thesis was coupling the solid phase microextraction (SPME) to graphite furnace atomic absorption spectrometer (GF AAS) for extracting the organometallic species volatilized in the drying and pyrolysis steps of the GF AAS. For evaluating the SPME-GF AAS coupling, Sn was then chosen. Firstly, the total Sn concentration using the slurry sampling strategy was determined, once in the evaluation of the organotin compounds by SPME-GF AAS, the total Sn concentration would be obtained from a slurry solution. Some parameters were evaluated, such as the nature of the solution to prepare the slurry, and pyrolysis and atomization temperatures effects. The mixture of 10 % (v/v) HF plus 1 % (v/v) HNO3 was chosen to prepare the sediment slurries, the Mg(NO3)2 plus NH4H2PO4 was appropriated as conventional chemical modifier, and the values of 1000 and 2000 °C was used as pyrolysis and atomization temperatures, respectively. The analyte addition was used in the Sn determination in sediment (marine and river) samples by slurry sampling due to matrix effects. The detection and quantification limits were calculated as 1.5-2.6 and 4.5-7.6 µg g, respectively. For evaluating the SPME-GF AAS coupling in the extraction of organotin species (butyltrichloride, dibutyldichloride, and tributylchloride), a sediment slurry was firstly used. For this task, the slurry was sonicated and an aliquot of this solution plus the derivatization reagent (sodium tetraethylborate ¿ NaBEt4) were introducted consecutively into the graphite furnace of the GF AAS. Then, the graphite furnace program was applied, and the SPME fiber was exposed into the furnace. After the extraction of organotin species by SPME-GF AAS, the analytes were separated and detected by gas chromatography (GC). Before this procedure, instrumental parameters of the GC were studied. For this task, it was used the conventional extraction by HSSPME (headspace-solid phase microextraction). Related to studies of SPME-GF AAS coupling, employing slurry sampling, some parameters, such as fiber coating, derivatization reagent concentration, pH of the reaction, among others, were evaluated. Satisfactory results were obtained using the PDMS/DVB fiber in the presence of 0.2 % (m/v) NaBEt4 and pH 5.0. However, low extraction efficiency (< 20 %) was obtained, using the SPME-GF AAS coupling for organotin species extraction from sediment slurries, when comparing to HS-SPME extractions. Then, the extraction of organotin species from sediment samples, using the ultrasonic energy was carried out, before the sample introduction into the SPME-GF AAS coupling. In this step, the graphite furnace temperature and the fiber exposure time in the atomizer were optimized. The better results were noted when 90 °C as the graphite furnace temperature was used, and 986 s was attributed as the fiber exposure time into the atomizer. Additionally, the determination of total Sn concentration, and the extraction of organotin species in the SPME fiber, using the SPME-GF AAS coupling, was simultaneously carried out.
Doutorado
Quimica Analitica
Doutor em Ciências
Wondracek, Marcos Henrique Pereira [UNESP]. "Síntese e aplicação de sílica modificada na adsorção de Cu(II), Cd(II) e As(V) em meio aquoso: pré-concentração em amostras de águas naturais." Universidade Estadual Paulista (UNESP), 2017. http://hdl.handle.net/11449/152253.
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Item merged in doublecheck by Monique Sasaki (sayumi_sasaki@hotmail.com) on 2017-12-07T17:59:08Z Item was identical to item(s): 153113, 153193 at handle(s): http://hdl.handle.net/11449/152063, http://hdl.handle.net/11449/152164
Este trabalho relata o desenvolvido de métodos analíticos que visa à determinação de algumas espécies tóxicas e potencialmente tóxicas de metais e metalóides em níveis ultra-traço em amostra de água naturais, utilizando uma técnica analítica menos sensível, como a espectrometria de absorção atômica em chama (FAAS). Essa técnica foi escolhida por ser relativamente simples e possuir baixo custo operacional. A técnica de extração em fase sólida (EFS), utilizando um novo material sorvente, foi utilizada para separar e pré-concentrar os analitos. Este estudo demonstra o procedimento de uma nova rota sintética via co-condensação visando à produção de uma sílica mesoporosa organofuncionalizada com o ligante 4-amino-3-hidrazino-5-mercapto-1,2,4-triazole e, sua utilização como sorvente para pré-concentração/análise de especiação de íons metálicos em amostras de água. O material produzido foi caracterizado por espectroscopia na região do infravermelho (FTIR), BET, ressonância magnética nuclear (RMN) de 29Si e 13C, dentre outras. As características adsortivas desse material foram estabelecidas em estudos de batelada, onde se estudou o efeito do pH, cinética de adsorção e capacidade máxima de adsorção. A otimização multivariada foi utilizada para obtenção das melhores condições químicas e de fluxo no sistema de pré-concentração, permitindo avaliar as interações principais e secundárias entre os fatores. Por meio da análise dos espectros obtidos por FTIR foi possível observar bandas de estiramento C–H, C–Cl e (NH2) oriundos da fração orgânica do material. A área superficial foi de 369,84 m2 g-1com diâmetro médio de poros em 7,1 nm, relacionados a materiais mesoporosos. Os resultados obtidos por RMN de 29Si comprovam a formação do material híbrido, sintetizado por co-condensação, e o RMN de 13C confirma o ancoramento do ligante na matriz. O pH que favorece a adsorção dos íons foi 5,0 para Cu(II) e 3,0 para Cd(II) e As(V). O modelo cinético de pseudo segunda ordem apresentou melhor ajuste aos dados experimentais, indicando adsorção química. Os dados de sorção desses íons metálicos mostraram bom ajuste ao modelo de Langmuir, com capacidade máxima de adsorção próxima aos valores obtidos experimentalmente, 0,057, 0,018 e 0,060 mmol g-1 para Cu(II), Cd(II) e As(V), respectivamente, indicando que a sorção ocorre em monocamada. Os parâmetros analíticos encontrados para o Cu(II) foram: fator de pré-concentração de 18,1; intervalo linear de 10,0 – 200,0 µg L-1 (R = 0,999) e LD de 1,45 µg L-1. Para o Cd(II): fator de pré-concentração de 15,8; intervalo linear de 2,0 – 100,0 µg L-1 (R = 0,999) e LD de 0,38 µg L-1. Para o As(V): fator de pré-concentração de 5,0; intervalo linear de 0,25 – 2,5 µg L-1 (R = 0,999) e LD de 0,039 µg L-1. A exatidão foi checada pelo método de adição e recuperação e/ou método comparativo com GFAAS ou ICP OES. As recuperações variaram de 97 – 106% (Cu), 100 – 105% (Cd), 88 – 103% (As(V)) e 96 – 106% (As(total)). Os resultados para Cu(II) determinados com os métodos propostos foram concordantes com os obtidos com o método comparativo. Conclui-se que o material produzido apresenta bom potencial para ser aplicado na extração/pré-concentração de cobre, cádmio e análise de especiação inorgânica de arsênio. Provou-se também que baixos limites de detecção e quantificação podem ser obtidos mesmo utilizando uma técnica menos sensível como a FAAS.
This paper reports on the development of analytical methods for the determination of some toxic and potentially toxic species in ultra - trace levels in natural water samples using a less sensitive analytical technique such as flame atomic absorpti on spectrometry (FAAS). This technique was chosen because it is relatively simple and has a low operating cost. The solid phase extraction technique (SPE) using a new sorbent material was used to separate and preconcentrate the analyte. This study demonstr ates the procedure of a new synthetic route using the technique of the co - condensation for the production of a mesoporous organo - functionalised silica with the 4 - amino - 3 - hydrazino - 5 - mercapto - 1,2,4 - triazole ligant and its use as a sorbent for preconcentrati on/ analysis of metal ion s speciation in water samples. The material produced was characterized by infra - red spectroscopy (FTIR), BET, 29 Si and 13 C nuclear magnetic resonance (NMR), among others. The adsorptive characteristics of this material were establis hed in batch studies, where the effect of pH, adsorption kinetics and maximum adsorption capacity were studied. Multivariate optimization was used to obtain the best chemical and flow conditions in the preconcentration system, allowing the evaluation of th e main and secondary interactions among the factors. By means of the analysis of the spectra obtained by FTIR, it was possible to observe C - H, C - Cl and (NH 2 ) stretch bands from the organic fraction of the material. The surface area was 369.84 m 2 g - 1 with a verage pore diameter at 7.1 nm related to mesoporous materials. The results obtained by 29 Si NMR prove the formation of the hybrid material, synthesized by co - condensation, and the 13 C NMR confirms the anchoring of the ligan t in the matrix. The pH 5.0 it w as favors the adsorption of the ions Cu (II), the pH 3.0 it was favors the adsorption of the Cd (II) and As (V). The kinetic model of pseudo second order showed better adjustment to the experimental data, indicating chemical adsorption. The adsorption data of Cu (II), Cd (II), and As (V) were similar to those of the Langmuir model, with a maximum adsorption capacity of 0.057, 0.018 and 0.060 mmol g - 1 for Cu (II), Cd(III) and As(V) , respectively, indicating that the sorption occurs in monolayer. The analyt ical parameters for Cu (II) were: preconcentration factor of 18.1; linear range of 10.0 - 200.0 μg L - 1 (R = 0.999) and LD of 1.45 μg L - 1 . For Cd (II): preconcentration factor of 15.8; linear range of 2.0 - 100.0 μg L - 1 (R = 0.999) and LD of 0.38 μg L - 1 . Fo r As (V): preconcentration factor of 5.0; linear range of 0.25 - 2.5 μg L - 1 (R = 0.999) and LD of 0.039 μg L - 1 . Accuracy was checked by addi tion and recovery method of the standard and/ or comparative method with GFAAS or ICP OES. The recovery ranged from 97 - 106% Cu(II), 100 - 105% Cd (II), 88 - 103% As (V) and 96 - 106% As (total)). The results for Cu (II) determined with the proposed methods were concordant with those obtained with the comparative. It is concluded that the material produced can be successfully applied in the extraction / preconcentration of copper, cadmium and analysis of inorganic speciation of arsenic and low limits of detection and quantification can be obtained even using a less sensitive technique such as FAAS.
Milani, Narges. "Zinc oxide nanoparticles in the soil environment : dissolution, speciation, retention and bioavailability." Thesis, 2012. http://hdl.handle.net/2440/82374.
Повний текст джерелаThesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 2012
Lin, Po-Chang, and 林伯璋. "Low-temperature phase transformation of ZnS and photochemical properties of Ag-In-Zn-S solid solution." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/37068979749559734971.
Повний текст джерела國立中正大學
化學工程研究所
101
Renewable and hydrogen energy are considered solutions for future energy. Solar energy has attracted increasing attentions. Combining these two fields, photocatalyst technology has become an important research area; for example, hydrogen generation from water splitting, methane synthesis and methanol synthesis etc. The solid solutions of Ag-In-Zn-S (AIZS), Cu-In-Zn-S (CIZS) and Ag-Cu-In-Zn-S (ACIZS) with adjustable band gaps possess high hydrogen production activities. However, thin film fabrication process was restricted to the high-temperature thermal treatment (850 °C) leaded to the damage of ITO glass substrate. The hydrogen production rate is related to the band gap of photocatalyst. Generally, the optimal band gap was believed approximated 2.3 eV for these materials. Our investigation stared with wurtzite ZnS, the same phase type with AIZS. The formation temperature of AIZS is expected to be lower than 850 °C when the phase transformation of ZnS is absence. The transition temperature of wurtzite type for pure ZnS is rather high, as 1020 °C. Although there were many articles reporting synthetizing WZ-ZnS at lower temperatures, it was very difficult to obtain WZ-ZnS high-purity. This study controlled the levels of ZnO content in the final products by different amounts of NaOH, WZ-ZnS can be obtained after annealing at 350 °C ~ 700 °C. As opposed to the temperature reduction induced by a smaller particle size, this research pointed out that the existence of ZnO is another critical factor to reduce the processing temperature. Unfortunately, the temperature reduction of AIZS formation is only 50 °C when we utilize WZ-ZnS as a seed to start the reaction. This result drove us to modify our strategy from a chemical bath deposition to the electrophoretic deposition. The annealed powders were deposited on subtracts directly, and the photocurrent of 0.137 mA/cm2 can be obtained successfully in a sacrificial reagent with Na2S and K2SO3. We also varied the compositions of AIZS by increasing the indium content. The indium-rich samples did not induce phase separation between AgxInxZnyS2x+y and AgIn5S8, instead forming a single-phase solid solution. Compared to the steady H2 evolution rate of Pt-loaded photocatalyst obtained with equal moles of indium and silver, that obtained with In-rich photocatalyst is over 5.86 times higher even though the band gaps were fixed. This study demonstrates the interaction, Pt loading and In2S3, played more critical role than band gap on the hydrogen production rate. We further synthesized the crystalline powders of AIZS, CIZS, and ACIZS by solid-state reaction. The H2 evolution rates were compared with the same condition (sacrificial reagent, co-catalyst, luminescence intensity and temperature). UV-Vis spectra and Ultraviolet Photoelectron Spectroscopy (UPS) were employed to identify the Fermi level, valence band and conduction band edges of each samples. These data provide additional information for the physical origin of high-efficiency photocatalyst. Based on the aforementioned findings, the property of band gap adjustable in AIZS, CIZS and ACIZS can be used to tune the relative levels of energy band between the photocatalyst layer and the barrier layer. This strategy can be applied to restrain the photocorrosion and enhance the photocurrent in the future.
Bérillon, Laurent [Verfasser]. "Mg- and Zn-mediated synthesis of heterocycles in solution and on the solid phase / von Laurent Bérillon." 2000. http://d-nb.info/960908374/34.
Повний текст джерелаBos, Mark C. "Part I : development and application of an arsenic speciation technique using ion-exchange solid phase extraction coupled with GFAAS ; Part II : investigation of zinc amalgam as a reductant." Thesis, 1996. http://hdl.handle.net/1957/34660.
Повний текст джерелаGraduation date: 1996
Pereira, Andreia Filipa Dias. "Understanding colloidal speciation events of ASDs through advanced screening tools." Master's thesis, 2019. http://hdl.handle.net/10362/89618.
Повний текст джерелаLee, Cheng-Fa, and 李正發. "Nano-TiO2 Solid-phase Extraction/Separation Coupled with Flow Injection-Atomic Absorption Spectrometer for Heavy Metal Speciation and Its Biomedical and Environmental Applications." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/66459507557077623722.
Повний текст джерела高雄醫學大學
醫學研究所
101
This study describes the development of analytical methods that used nano-TiO2 solid-phase extraction/separation coupled with flow injection (FI)-atomic absorption spectrometry (AAS) for heavy metal speciation. The proposed nano-TiO2 solid-phase extraction/separation-FI-AAS system was validated and applied to the detection of heavy metal species in human urine and environmental water samples. Three methods are presented in this study. Firstly, an on-line nano-TiO2 solid-phase extraction/separation coupled with FI-electrothermal AAS (ETAAS) system was developed for the separation of Se(IV) and Se(VI) in urine samples. The 0.02 M NaOH solution was used to elute the Se(IV) and Se(VI) species from the surface of nano-TiO2 film reactor and the eluent was introduced into the graphite tube by a flow injection system. The detection limits was 0.31 μg L-1 and 0.25 μg L-1 for Se(IV) and Se(VI), respectively. The precisions of the developed method for Se(IV) and Se(VI) were in the rages of 2.1 - 7.4%. The recoveries of Se(IV) and Se(VI) in urine samples were in the rages of 93.9 - 112.2%. The average concentrations of Se(IV) and Se(VI) in urine of patients with diabetes mellitus were found to be 5.7 and 10.5μg L-1, respectively. In subsequent part, an on-line nano-TiO2 photocatalysis reduction device coupled with FI-ETAAS was developed for chromium speciation. The process of chromium speciation in urine was based on the adsorption of Cr(III) and Cr(VI) on this photocatalysis reduction device. The absorbed Cr(VI) was photoreduced to Cr(III), and Cr(III) was eluted using 1.0 M formic acid. The detection limit for Cr(III) and Cr(VI) using this analytical method was 0.08 and 0.13 μg L-1, respectively. The precisions for the analysis of Cr(III) and Cr(VI) were in the range of 4.0 - 6.2%. The spiked recoveries were in the range of 96.0 - 98.3% for the determination of Cr(III) and Cr(VI). This analytical method was applied to the determination of Cr(III) and Cr(VI) in urine samples of human volunteers, during which samples were taken before and after the volunteers’ diets supplemented with chromium picolinate. Lastly, due to the complexity for separating the four arsenic speciesof interest, an analytical method was developed for the determination of them in environmental water samples using a nano-TiO2 solid-phase extraction/separation coupled with atomic absorption spectrometry. The separation of the four arsenic species was based on the selective adsorption of arsenic species onto the surface of TiO2 film at pH 3 or 10 and their subsequent selective desorption through elution with 50 mM NH4H2PO4, 50 mM (NH4)2C2O4 and 50 mM CH3COONH4 solution. The detection limits for As(III), As(V), MMA, and DMA was 0.17, 0.18, 0.14, and 0.11 μg L–1, respectively. The precisions of this analytical method for four arsenic species were in the range of 0.7 - 8.1%. The recoveries for As(III), As(V), MMA, and DMA spiked in water samples were in range of 90.4 - 107.3%. This proposed method was successfully applied for the speciation of four arsenic species in well water samples. In summary, the results of this study confirmed that a nano-TiO2 solid-phase extraction/separation coupled with atomic absorption spectrometry would be a novel and foresighted method for trace metal speciation and could benefit the exploration of trace heavy metals in biomedicial and environmental sciences.
Biaduń, Ewa. "Przygotowanie próbek wód zanieczyszczonych do analizy specjacyjnej As, Cr i Tl." Doctoral thesis, 2019. https://depotuw.ceon.pl/handle/item/3459.
Повний текст джерелаSample preparation for speciation analysis is a difficult task, practically each sample and each analyte requires unique analytical scenarios. As, Cr i Tl belong to the group of elements included in the list of research priorities of the American Environmental Protection Agency (US EPA). Toxicity, mobility, or bioavailability of many elements depend on their oxidation state and chemical form. For this reason speciation analysis is an important element of modern environmental monitoring. The most toxic forms of As are inorganic compounds, while organic arsenic compounds are non-toxic. Cr(III) compounds are less soluble and more stable, while Cr(VI) compounds are more soluble and mobile in the natural aqueous environment. Tl(III) compounds are more toxic than Tl(I) compounds. Water, which is an abiotic element of the environment, is responsible for transport of pollutants and changes of the speciation forms of elements. Water can be divided into two phases: dissolved phase which is responsible for the transport of pollutants and suspended particulate matter (SPM) which is responsible for co-precipitation of chemical forms of As, Cr and Tl. Water samples containing surface active compounds were collected. The affinity of selected As, Cr and Tl forms for SPM was checked. The speciation forms were separated and preconcentrated using solid phase extraction. Various sorbents have been applied, e.g. SGX C18 modified with ammonium pyrolidinedithiocarbamate and alumina modified with sodium dodecyl sulphate (SDS). The possibility of simultaneous separation of As(III), Cr(III) and Tl(III) from water was tested. However, a complete procedure was developed only for separation and preconcentration of Tl(III) from the water matrix. Next, the possibility of application of photocatalysts: tungsten and iron oxides for decomposition of surface-active compounds before the speciation of As, Cr and Tl was tested. Different active layers consisting of tungsten and iron oxides have been proposed. These active layers were evaluated during the decomposition of SDS and Triton X-114. Decomposition efficiency was evaluated on the basis of voltammetric determination of trace amounts of Pb(II) with a mercury electrode, which is very sensitive to interferences from organic compounds. Selected photolayers were tested in the degradation of organic compounds before speciation analysis of arsenic, chromium and thallium. A complete procedure (from sampling to determination) for analysis of As and Tl compounds in waters with high content of surfactants was developed. Analytical scenarios based on photocatalysis could be included in the modern environmental monitoring.
Kińska, Katarzyna. "Wpływ emisji platynowców na środowisko." Doctoral thesis, 2018. https://depotuw.ceon.pl/handle/item/2854.
Повний текст джерелаIntroduction of car catalysts for general use caused an increase in emissions of platinum group elements (PGEs) to the environment. The increased level of platinum, palladium and rhodium is observed, especially in the vicinity of main communication routes, but still, rarely exceeds 1 μg g-1. The aim of the doctoral thesis was to determine an impact which PGEs may have on the environment. To make that possible, it's necessary to develop procedures, guaranteeing both, determination of the total content of analytes at appropriate concentration levels, as well as monitoring the changes they undergo and identification of their chemical forms. In order to get the reliable results, particular attention should be paid to the proper way of sample preparation before analysis. The determination of trace amounts of platinum, rhodium or palladium in environmental samples is not a simple task. The complexity of the sample matrix and the low concentration level of analytes cause that the determination methods must have sufficiently low limits of quantification. Often an additional step of analytes pre-concentration and separation from the matrix is introduced in the analytical procedure. As a part of the conducted research, the digestion procedures of soil and quartz sands samples, using the mixture of HNO3 and HCl acids, were optimized. Based on the results obtained for certified reference material (BCR-723; road dust) the possibility of efficient analytes transfers into the solution was proven. To isolate analytes from the matrix the solid phase extraction method was suggested. During the experiments, cation and anion exchange sorbents, as well as the eluents of various elution strength were used: 0.10 mol L-1 thiourea in 0.10 mol L-1 HCl, 2.0 mol L-1 HCl, 0.025-0.053 mol L-1 ammonium buffer. Developed sample preparation procedures were used to monitor PGEs in soil and quartz sands samples received from the monitoring plots distributed along high-ways and exposed to traffic-related contamination. Particular attention was paid to the possibility of using adsorptive stripping voltammetry (AdSV), which, due to low limits of quantification, can be an alternative method to inductively coupled plasma mass spectrometry (ICP MS). Based on the results obtained, the influence of road traffic on the increasing environmental pollution was proven, along with the indication of car catalysts as main emitters of the platinum group elements. The deposition of PGEs in soils makes that they can be taken up and accumulated by plants, which may cause disturbances in their proper functioning. The influence of platinum, palladium and rhodium on the growth of white mustard (Sinapis alba L.) was defined based on the plant material obtained from hydroponic cultivation. The plants, exposed to stress from the presence of various salts and nanoparticles of PGEs, have been characterized for the total content of metals taken from the nutrient solution and transported to aboveground organs (ICP MS), the presence of nanoparticles in selected tissues (SP ICP MS, TEM) and the formation of complexes with ligands present or de novo synthesized in the plant. The phytochelatins (PC2, PC3 and PC4), formed in plant cells, were identified by high-performance liquid chromatography with fluorescence detection (HPLC FLD) and electrospray ionization mass spectrometry (ESI MS). Additionally, thanks to the use of the SEC ICP MS method, some palladium compounds formed in Sinapis alba L. cells were detected and separated. The application of HILIC ESI MS method enabled identification of several Pd complexes with organic ligands, like histidine and nicotianamine, responsible for metal detoxification processes.