Submitted by JÚLIO HEBER SILVA (julioheber@yahoo.com.br) on 2018-05-10T17:06:11Z No. of bitstreams: 2 Dissertação - Carolina Aparecida de Sousa Silva - 2018.pdf: 2891797 bytes, checksum: c1079049ce0d92f7213a7f8f71e94f4a (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2018-05-10T18:11:50Z (GMT) No. of bitstreams: 2 Dissertação - Carolina Aparecida de Sousa Silva - 2018.pdf: 2891797 bytes, checksum: c1079049ce0d92f7213a7f8f71e94f4a (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2018-05-10T18:11:50Z (GMT). No. of bitstreams: 2 Dissertação - Carolina Aparecida de Sousa Silva - 2018.pdf: 2891797 bytes, checksum: c1079049ce0d92f7213a7f8f71e94f4a (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2018-04-20 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The iron oxide (Fe3O4) nanoparticles are promising adsorbents and, in this work, they were synthesized, characterized and applied as adsorbents in the adsorption of lead ions (Pb2+) using solid phase magnetic extraction (MSPE). The iron oxide was synthesized by the coprecipitation method and the obtained nanoparticles presented the crystalline phase of the oxide, being proved by the characterization by X-Ray Diffraction, X-ray Dispersive Energy and Absorption Spectroscopy in the Infrared region. In order to obtain information on the surface charge of the synthesized material, the pH at the zero loading point (pHPCZ) was determined indicating that the oxide surface is negatively charged at pH values above 9.4. Once the best pH (9.0) for adsorption was defined, the influence of the variables agitation time and mass of the adsorbent were evaluated, fixing them in 4 min and 3.0 mg respectively, in order to obtain the best conditions of the adsorption. adsorption process. The maximum adsorption capacity was obtained by the construction of adsorption isotherms, and a value of 31.60 mg.g1 was found. Through the kinetic study, it was observed that the adsorption obeys a pseudo-first-order kinetics. After the adsorption was optimized, the best desorption parameters were evaluated, aiming the development of an extraction/preconcentration method. Thus, 500μL of 0.5 mol.L-1 nitric acid was used as the eluent. The analytical performance was evaluated by means of the parameters, limit of detection (L.D.), limit of quantification (L.Q.), precision (D.P.R) and values found were 5.44 μg.L-1 ; 16.48 μg.L-1 and 0.25%, respectively, with the linear range of the method being 16.48 -500 μg.L-1 . Finally, the accuracy of the method was evaluated from recovery tests on samples of mineral water, micellar water and facial makeup with recovery values in the range of 95.94 - 118%. In addition, analyzes of certified water reference material (APS-1071) were also made to verify the accuracy of the proposed method. / As nanopartículas de óxido de ferro (Fe3O4) são adsorventes promissores e, neste trabalho foram sintetizadas, caracterizadas e aplicadas como adsorvente na adsorção de íons chumbo (Pb2+) utilizando extração magnética em fase sólida (MSPE). O óxido de ferro foi sintetizado pelo método de coprecipitação e as nanopartículas obtidas apresentaram a fase cristalina do óxido, sendo comprovado através da caracterização por Difração de Raio X, Energia Dispersiva de Raio X e Espectroscopia de Absorção na região do Infravermelho. A fim de se obter informações sobre a carga superficial do material sintetizado, o pH no ponto de carga zero (pHPCZ) foi determinado indicando que a superfície do óxido se encontra carregada negativamente em valores de pH acima de 9,4. Uma vez definido o melhor pH (9,0) para adsorção, a influência das variáveis tempo de agitação e massa do adsorvente foram avaliadas, fixando-as em 4 min e 3,0 mg respectivamente, a fim de se obter as melhores condições do processo de adsorção. A capacidade de adsorção máxima foi obtida pela construção de isotermas de adsorção, tendo sido encontrado um valor de 31,60 mg.g-1 . Através do estudo cinético, observou-se que a adsorção obedece uma cinética de pseudo-primeira-ordem. Após ter a adsorção otimizada, foram avaliados os melhores parâmetros para dessorção, visando o desenvolvimento de um método de extração/pré-concentração. Assim, 500µL de ácido nítrico 0,5 mol.L-1 foram utilizados como eluente. O desempenho analítico foi avaliado por meio dos parâmetros, limite de detecção (L.D.), limite de quantificação (L.Q.), precisão (D.P.R) e os valores encontrados foram 5,44 μg.L-1 ; 16,48 μg.L-1 e 0,25%, respectivamente, sendo a faixa linear do método igual a 16,48 –500 μg.L-1 . Por fim, a exatidão do método foi avaliada a partir de testes de recuperação em amostras de água mineral, água micelar e demaquilante facial com valores de recuperação na faixa de 95,94 – 118%. Além disso, análises de material certificado de referência de água (APS-1071) também foram feitas para constatar a exatidão do método proposto.

Made available in DSpace on 2014-10-09T12:34:02Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:59:37Z (GMT). No. of bitstreams: 0 / Composições cerâmicas de CaxSr1-xTi1-yFeyO3-&delta;, x = 0, 0,5 e 1,0, y = 0 e 0,35, foram preparadas por meio de síntese reativa de CaCO3, SrCO3, TiO2 e Fe2O3 e pela técnica dos precursores poliméricos. Os pós-cerâmicos foram avaliados por meio de análise térmica (termogravimétrica e térmica diferencial), difração de raios X e microscopia eletrônica de varredura. Compactos cerâmicos sinterizados foram analisados por difração de raios X, microscopia eletrônica de varredura, microscopia de varredura por sonda e espectroscopia de impedância. A força eletromotriz gerada entre duas faces paralelas de amostras cilíndricas foi monitorada na faixa de temperatura 600 - 1100 oC para pressão parcial de oxigênio de ~50 ppm, utilizando-se uma bomba eletroquímica de oxigênio com transdutores de zircônia estabilizada com ítria. Foram refinadas, por meio de análise de Rietveld as estruturas cristalinas determinadas na análise por difração de raios X: perovskita cúbica (x = 0) e perovskita ortorrômbica (x 0). A condutividade elétrica foi analisada por medidas de espectroscopia de impedância na faixa de freqüências 5 Hz-13 MHz da temperatura ambiente até ~200 C. A deconvolução dos diagramas de impedância [-Z\"() x Z\'()] na faixa de temperaturas 300 < T(K) < 500 mostra dois semicírculos atribuídos às contribuições intragranular (grãos) e intergranular (contornos de grão) à resistividade elétrica. Os compactos sinterizado utilizando pós preparados pela síntese de estado sólido apresentam valores de resistividade intergranular e intragranular maiores que os compactos preparados com pós obtidos pela síntese química. O sinal elétrico (força eletromotriz) gerado sob exposição a oxigênio mostra que esses compostos podem ser utilizados em dispositivos sensores de oxigênio entre 600 e 1100C. Análises topográficas em microscópio de varredura por sonda em superfícies polidas e atacadas termicamente mostram detalhes morfológicos dos grãos, permitindo concluir que compactos sinterizados preparados com pós obtidos pela rota química são menos porosos que os preparados com pós obtidos pela rota convencional de síntese de estado sólido. Estes resultados estão de acordo com os resultados de medidas de espectroscopia de impedância. / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:48:42Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:59:46Z (GMT). No. of bitstreams: 1 09305.pdf: 5404217 bytes, checksum: 19eda8ad49f8cd247304fef0fb69c1bc (MD5) / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2014-10-09T12:51:44Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:08:36Z (GMT). No. of bitstreams: 0 / Investiga-se a influência de diferentes tratamentos sobre o sistema alumínio com cobertura de óxido de alumínio. A anodização do alumínio em meio de ácido sulfúrico e meio misto de sulfúrico e fosfórico foi empregada para alterar a resistência à corrosão, a espessura, o grau de cobertura e a microdureza do óxido anódico; e a eletrodeposição de ferro no interior óxido anódico em meio de sulfato com tratamento químico de selagem com cério, para alterar a sua condutividade elétrica e a sua resistência à corrosão. Para a eletrodeposição de ferro aplicou-se corrente contínua e pulsada e diversificou-se a composição do eletrólito de Fe(SO4)2(NH4)2.6H2O, com a adição dos ácidos bórico e ascórbico e para o tratamento de selagem, variou-se a concentração do CeCl3. A espectroscopia de energia dispersiva de raios X (EDS), a fluorescência de raios X (FRX) e a análise morfológica por microscopia eletrônica de varredura (MEV) permitiram verificar que, a corrente pulsada eleva o teor de ferro na camada anódica e a presença dos aditivos inibe a oxidação do ferro. As curvas cronopotenciométricas obtidas durante a eletrodeposição de ferro indicaram que a mistura dos ácidos bórico e ascórbico aumentaram a eficiência do processo de eletrodeposição. A espectroscopia de impedância eletroquímica (EIE), medidas de microdureza Vickers (H) e análise morfológica evidenciaram que o tratamento de selagem melhora a resistência à corrosão do filme óxido modificado com ferro. As medidas de impedância elétrica por duas pontas permitiram comprovar o aumento da condutividade elétrica do alumínio anodizado com ferro, mesmo após o tratamento com baixas concentrações de cério. Nanofios de ferro foram preparados utilizando os poros do óxido anódico como matriz. / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Les métaux lourds et les radionucléides sont présents dans différents écosystèmes du monde à cause de contaminations naturelles ou des activités anthropiques. L’utilisation de micro-organismes pour restaurer ces écosystèmes pollués, processus connu sous le nom de bioremédiation, suscite beaucoup d’intérêt, spécialement aux pH proches de la neutralité. Les minéraux de fer qui encroûtent les bactéries neutrophiles du fer, notamment les Oxydes de Fer Biogéniques (BIOS en anglais), ont une structure très faiblement cristalline, qui en plus de leur grande surface et réactivité font d’eux d’excellents supports pour le piégeage de polluants inorganiques. Dans cette thèse nous avons étudié les différents mécanismes de piégeage de l’uranium uranium par la bactérie neutrophile Sphaerotilus natans, choisie comme modèle bactérien de micro-organismes du fer capables de filamenter en formant des gaines. S. natans peut croître sous forme de cellules individuelles ou formant des filaments. Ces derniers ont été utilisés pour étudier la biosorption d’U(VI) et sa sorption sur les BIOS. De plus, la sorption d’U(VI) sur les analogues abiotiques de ces minéraux de fer a été testée. Afin d’utiliser les filaments de S. natans pour piéger l’U(VI), il était nécessaire d’identifier les facteurs induisant la filamentation de S. natans. L’influence de l’oxygène a été établie en utilisant des techniques de biologie moléculaire et nos résultats ont démontré que tandis qu’en condition d’oxygène saturé elle croît sous forme de cellules individuelles, une diminution modérée d’oxygène à ~ 3 mg O2.L-1 la fait croître sous la forme désirée, des filaments de S. natans.Les BIOS attachés aux filaments de S. natans ainsi que ses analogues abiotiques ont été analysés pas XAS au seuil K du Fe. Les deux matériaux identifiés sont des phosphates de fer(III) amorphes avec une faible proportion de fer(II), qui présentent une réactivité élevée pour le piégeage de polluants inorganiques. L’EXAFS au seuil LIII de l’U a montré la même structure pour les couches O, tandis que celles P, Fe et C étaient différentes en fonction des sorbants. Une étude intégrée qui combine des techniques expérimentales avec des calculs de spéciation a permis de décrire les isothermes d’adsorption de l’U(VI) en utilisant un modèle de complexation de surface. Ces résultats suggèrent que les groupes phosphoryles et carboxyles sont les groupes fonctionnels principaux pour la biosorption d’U(VI) par des filaments de S. natans. Les résultats de cette thèse vont aider à comprendre les processus contrôlant l’immobilisation de l’U(VI), soit par la biosorption sur S. natans, la sorption sur les BIOS ou la sorption sur les phosphates de fer, et en conséquence le devenir de l’U en conditions neutres / Heavy metals and radionuclides are present in some ecosystems worldwide due to natural contaminations or anthropogenic activities. The use of microorganisms to restore those polluted ecosystems, a process known as bioremediation, is of increasing interest, especially under near-neutral pH conditions. Iron minerals encrusting neutrophilic iron-related bacteria, especially Bacteriogenic Iron Oxides (BIOS), have a poorly crystalline structure, which in addition to their large surface area and reactivity make them excellent scavengers for inorganic pollutants. In this PhD work we studied the different mechanisms of uranium scavenging by the neutrophilic bacterium Sphaerotilus natans, chosen as a model bacterium for iron-related sheath-forming filamentous microorganisms. S. natans can grow as single cells and filaments. The latter were used to investigate U(VI) biosorption and U(VI) sorption onto BIOS. In addition, uranium sorption onto the abiotic analogues of such iron minerals was assessed. In order to use S. natans filaments for U(VI) scavenging, it was necessary to identify factors inducing S. natans filamentation. The influence of oxygen was ascertained by using molecular biology techniques and our results revealed that while saturated oxygen conditions resulted in single cell growth, a moderate oxygen depletion to ~ 3 mg O2.L-1 led to the desired filamentous growth of S. natans. BIOS attached to S. natans filaments as well as the abiotic analogues were analysed by XAS at Fe K-edge. Both materials were identified as amorphous iron(III) phosphates with a small component of Fe(II), with a high reactivity towards scavenging of inorganic pollutants. In addition, EXAFS at the U LIII-edge revealed a common structure for the O shells, while those for P, Fe and C were different for each sorbent. An integrated approach combining experimental techniques and speciation calculations made it possible to describe U(VI) adsorption isotherms by using a surface complexation model. These results suggested the role of phosphoryl and carboxyl groups as the main functional groups involved in the U(VI) biosorption by S. natans. The results of this PhD work will help to better understand the processes governing U(VI) immobilization, either by S. natans biosorption, sorption onto BIOS or sorption onto iron phosphates, an thus the fate of uranium in near-neutral pH environments

The presence of deposits leading to corrosion of the steam generator (SG) systems is a major contributor to operation and maintenance cost of pressurized water reactor (PWR) plants. Formation and transport of corrosion products formed due to the presence of impurities, metallic oxides and cations in the secondary side of the SG units result in formation of deposits. This research deals with the characterization of deposit samples collected from the two SG units (unit 1 and unit 2) at Comanche Peak Steam Electric Station (CPSES). X-ray diffraction (XRD), Fourier transform infrared spectrophotometry (FTIR), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) techniques have been used for studying the compositional and structural properties of iron oxides formed in the secondary side of unit 1 and unit 2. Magnetite (Fe3O4) was found to be predominant in samples from unit 1 and maghemite (g-Fe2O3) was found to be the dominant phase in case of unit 2. An attempt has been made to customize FTIR technique for analyzing different iron oxide phases present in the deposits of PWR-SG systems.

Orientadora: Profa. Dra. Juliana Marchi / Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Nanociências e Materiais Avançados, Santo André, 2018. / A hipertermia e uma terapia de tratamento de cancer que consiste em aumentar a temperatura do tecido biologico contendo celulas cancerigenas a temperaturas ate 43¿C, a qual afeta as celulas cancerigenas e causa minimos danos a celulas saudaveis. Este trabalho visou sintetizar, pelo metodo sol-gel, vidros bioativos do sistema SiO2-CaO-P2O5 contendo fases magneticas de oxido de ferro a fim de obter um material com propriedades magneticas promissoras para hipertermia e com propriedades osteocondutoras favoraveis para regeneracao ossea, podendo assim ser utilizado no tratamento de cancer osseo. As fases magneticas foram introduzidas por dois diferentes metodos: I) cristalizacao por reacoes de estado solido (Parte I); II) dispersao de nanoparticulas de magnetita na matriz vitrea (Parte II). Na Parte I do trabalho, uma rota alternativa de sintese foi desenvolvida e validada para possibilitar a obtencao de vidros contendo fases superparamagneticas nucleadas por cristalizacao. Os materiais foram caracterizados por difracao de raios X (DRX), espectroscopia de infravermelho na transformada de Fourier, calorimetria diferencial de varredura (DSC) e magnetometro de amostra vibrante (VSM-SQUID). Os resultados indicaram que vidros obtidos pela metodologia modificada da Parte I apresentam estrutura quimica similar aos vidros obtidos pelo metodo convencional, i.e. uma fase vitrea contendo fase secundaria cristalina de hidroxiapatita. Foi possivel obter vidros contendo ferro, cuja incorporacao ocasiona uma conversao 3Q2 ¨ 2Q3 na estrutura vitrea, sugerindo um efeito de ion intermediario em relacao ao ferro. O tratamento termico de vidros contendo ferro a 670¿C induziu a nucleacao de nanocristais de hematita, fazendo que os vidros exibissem comportamento superparamagnetico. Na segunda parte deste trabalho (Parte II) os vidros foram obtidos pelo metodo quick-alkali onde as nanoparticulas de magnetita foram dispersas durante a sintese. Os materiais foram caracterizados por DRX, DSC, espectroscopia Raman, microscopia eletronica de varredura por emissao de campo e VSM-SQUID. Os resultados da Parte II indicaram que vidros contendo nanoparticulas de magnetita com propriedades superparamagneticas foram obtidos. Foi observado um efeito de aglomeracao das nanoparticulas, o qual afetou as interacoes dipolares entre as particulas. O processo da sintese induziu uma oxidacao das nanoparticulas de magnetita, levando a uma diminuicao do momento de saturacao, porem ainda com valores adequados para sejam empregados em tratamentos por hipertermia. Os resultados de ambas as Partes (I e II) indicam que materiais promissores para aplicacoes em hipertermia foram obtidos. / Hyperthermia is a cancer treatment therapy that consists of increasing the cancerous tissue temperature up to 45¿C, majorly affecting cancer cells, and minimally damaging healthy ones. The aim of this work was to synthesize, through the sol-gel method, bioactive glasses based on the SiO2-CaO-P2O5 and containing magnetic phases of iron oxide in order to achieve materials with suitable magnetic properties for hyperthermia, and desired biological properties for bone regeneration. Therefore, such material can be used in treatment of bone cancer. The magnetic phases were added in the glass structure by two different methodologies: I) crystallization through solid state reactions (Part I); II) dispersion of magnetite nanoparticles within the glass matrix (Part II). In Part I, an alternative synthesis route was developed and validated to obtain glasses containing superparamagnetic phases nucleated by crystallization.The prepared materials were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and vibrating sample magnetometer (VSM-SQUID). The results showed that glasses obtained by the adapted synthesis of Part I showed chemical structure similar to those glasses obtained by the conventional quick-alkali route, i.e., a glassy phase contenting hydroxyapatite crystals as residues. Iron-containing glasses were also obtained, and it was verified that iron diffusion the glass structure led to a 3Q2 ¨ 2Q3 silicate population conversion, suggesting an intermediate role for iron ions. Thermal treatment in the iron-containing glasses up to 670¿C induced to a hematite nanocrystals nucleation, which makes the glasses to exhibit superparamagnetic properties. .In Part II, the glasses were obtained through quick-alkali route, where magnetic nanoparticles were dispersed during the synthesis. The obtained materials were characterized by XRD, DSC, Raman spectroscopy and field-emission gun scanning electron microscopy and VSM-SQUID. Part II results highlighted that glasses containing magnetite nanoparticles exhibiting superparamagnetic properties were obtained. It was noted that a clustering effect of the magnetite nanoparticles affected dipole-dipole interactions. In addition, along the synthesis, magnetite underwent oxidation, which diminished the saturation moment, but it does not prevent the use of such materials for hyperthermia purposes. Finally, the overall results of both parts (I and II) indicated that promising materials for hyperthermia applications were obtained.

Gegenstand dieser Arbeit ist die wissensbasierte Untersuchung verschiedener Eisenoxid/-hydroxid-Modifikationen für die alternierende Entfernung von Schwefelwasserstoff und Sauerstoff aus regenerativ erzeugten Gasen. Dafür wurden 37 Eisenoxide/-hydroxide systematisch auf ihre H2S- und O2-Adsorption hin untersucht und in Kombination mit deren physikalisch-chemischen Eigenschaften Struktur-Aktivitäts-Korrelationen abgeleitet. Die Aufklärung der ablaufenden Reaktionsmechanismen erfolgte mit spektroskopischen Analysenmethoden (DRIFTS Raman). Relevante Betriebsparameter wurden an einem α-FeOOH systematisch im Labormaßstab ermittelt. Daneben steht die Übertragbarkeit der Laborergebnisse in die technische Anwendung im größeren Maßstab (Upscaling) und mit Realgas im Fokus. Zudem wurde eine Wirtschaftlichkeitsbetrachtung inklusive eines Vergleiches mit Konkurrenzverfahren durchgeführt.

Periglaziale Deckschichten auf carbonatreichen Gesteinen der geologischen Formation des Muschelkalks sind bisher nur peripher Gegenstand wissenschaftlicher Untersuchungen innerhalb der Deckschichtenfor-schung. Um diese Lücke zu schließen, widmet sich die vorliegende Arbeit dem Aufbau des oberflächenna-hen Untergrundes im Muschelkalk in einem Teilgebiet in der ostthüringischen Triaslandschaft. Die Ergebnisse zeigen, dass die periglazialen Deckschichten in Abhängigkeit von lithologischen Gesteins-merkmalen und Relieffaktoren (Exposition, Neigung) eine hohe räumliche Heterogenität hinsichtlich der stoff-lichen Zusammensetzung, der vertikalen Gliederung und Gründigkeit aufweisen. Sie sind in Basislagen (LB), Mittellagen (LM) und Hauptlagen (LH) gegliedert, die ihrerseits eigenständige Schichten beinhalten können. Die Lagenbildungen über carbonatreichen Gesteinen des Muschelkalks weisen Besonderheiten im Aufbau, in den stofflichen Eigenschaften und in ihrer Genese auf. Die Basislagen sind in der Regel mehrgliedrig entwickelt und können bis zu drei, faziell zu unterscheidende Substratkomplexe enthalten. Dies sind i) eine skelettfreie Kalksteinbraunlehm-Fließerde (LB-F), ii) ein Kalk-steinbraunlehmschutt (LB-1) und iii) ein Kalksteinschutt (LB-2). Die Zweiteilung der Basislagenschutte sowie die Abfolge LB-1/ LB-2 (LB-1 über LB-2) können als charakteristische Merkmale der Basislagenbildung über Muschelkalk herausgestellt werden. Skelettfreie Kalksteinbraunlehme (LB-F) stellen eine Besonderheit auf Carbonatgesteinen dar, da vergleichbare Bildungen auf quarz- und silikatreichen Standorten fehlen. Die Hauptlagen werden in eine schluffreiche (LH) und tonreiche (LHT) Fazies unterschieden. Beide zeichnen sich durch eine vollständige Skelettfreiheit aus, die ebenfalls als übergreifendes Merkmal über Muschelkalk gelten kann. Zwei Mittellagentypen sind mit skelettfreier Mittellage (LM) und skeletthaltiger Mittellage (LMs) vertreten. Die Genese der Basislagenabfolge LB-F/ LB-1/ LB-2 fand vollständig im Weichselglazial statt und schließt eine periglaziale Genese der Kalksteinbraunlehme ein. Die Beteiligung von Spülprozessen an der (Geli-) Solifluktion hat die Akkumulation von Lösungsrückständen (= Kalksteinbraunlehm) gefördert. Die Zweiteilung der Basisschutte kann ebenfalls durch die Mitwirkung ablualer Prozesse erklärt werden. Die Kalksteinbraun-lehm-Fließerde entstand synsedimentär zur Bildung der Basislagenschutte durch laterale Ausspülung. Die Variabilität der Lössedimente wird neben Luv-/Lee-Effekten und präsedimentäre karstartige Hohlformen vor allem auch über eine differenzierte periglaziale Bodenfeuchte- und Vegetationsverteilung gesteuert. In der Arbeit wurden u.a. der gU/fU-Quotient, pedogene Eisenoxide (Feo, Fed), Gesamteisengehalt (Fet), Fet/Ton-Quotient und (Fed-Feo/(Fet/Ton)-Quotient (nach GÜNSTER et al. 2001) sowie die Korrelation von Tongehalt und pedogenem Eisen für alle oben genannten Substrate ermittelt. Eine integrative Betrachtung dieser Parameter ist grundsätzlich geeignet, primäre Sedimenteigenschaften der Substrate herauszustellen und eine pedogenetische Überprägung abzugrenzen. Darüber hinaus erlauben sie Aussagen zur Genese. Der Tongehalt der Mittellagen konnte neben der Überformung durch Tonverlagerung als sedimentogene Ei-genschaft belegt werden. Kalksteinbraunlehme mit weniger als 65% Tongehalt müssen nicht grundsätzlich lösslehmbeeinflusst sein. Rezente Lösungsprozesse und eine rezente Weiterbildung der Kalksteinbraunleh-me konnten auch im Liegenden mächtigerer Lösssedimente nachgewiesen werden. Es wird gezeigt, wie die periglazialen Decksedimente in ihrer räumlichen, vertikalen und stofflichen Variabilität Einfluss auf die Heterogenität der Bodendecke nehmen.

M.Tech. (Department of Chemistry, Faculty of Applied and Computer Sciences), Vaal University of Technology / Water contaminated with non-biodegradable organics is becoming increasing problematic as it has a hazardous effect on human health and the aquatic environment. Therefore, the removal of organic contaminants is of importance and an active heterogeneous Fenton catalyst is thus required. The literature indicates that a bimetallic oxide Fenton catalyst is more active than an iron oxide catalyst. This study focused on increasing the activity of iron-based Fenton catalysts with the addition of transition metals such as manganese, cobalt and copper and optimizing the preparation method. In this study, bimetallic oxide (Fe-Cu, Fe-Mn, Fe-Co) and monometallic oxide (Fe, Cu, Mn,Co) catalysts supported on silica SiO2 where prepared by incipient wetness impregnation. The total metal oxide contents were kept constant. The catalysts where calcined in two different ways, in a conventional oven and in a microwave. These catalysts were characterized with XRD, XPS and CV and were tested for the degradation of methylene blue dye at 27°C. The catalysts calcined in a microwave oven had a higher catalytic activity than those prepared in a conventional oven. The bimetallic oxide catalysts outperformed the mono- metallic oxide catalysts in the degradation of methylene blue. The Fe2MnOx prepared by microwave energy were the most active catalyst yielding the highest percentage of degradation of methylene blue dye (89.6%) after 60 minutes. The relative amounts of manganese and iron oxide were varied while keeping the total metal content in the catalyst the same. The optimum ratio of Fe to Mn was 1:7.5 since it yielded the most active catalyst. A 96.6 % removal of methylene blue was achieved after 1 hour of degradation. Lastly this ratio 1Fe:7.5Mn was prepared by varying different microwave power (600, 700 and 800 W) and irradiation time (10, 20 and 30 min). The optimum microwave power and irradiation time was 800W and 10 min with the methylene blue percentage removal of 96.6 % after 1 hour of degradation.