Techn. Universiẗat, Diss., 2004--Dresden.

Organic ligands, such as EDTA, accelerate the dissolution of silicate and oxide minerals. In natural systems oxyanions can compete with organic ligands for mineral surface sites thereby affecting ligand-promoted dissolution rates. Oxyanions can either enhance or inhibit dissolution depending upon pH. It has been suggested that the type of surface complex formed by the oxyanion is responsible for differences in ligand-promoted dissolution rates with mononuclear being dissolution enhancing and bi- or multinuclear being dissolution inhibiting. However, recent research has demonstrated that the type of surface complex formed by the oxyanion is not responsible for differences in ligand-promoted dissolution rates of oxide minerals. Accordingly, this manuscript examines the influence of selenite, molybdate, and phosphate on the EDTA-promoted dissolution of goethite and proposes a mechanism for the observed differences in dissolution rates over a pH range of 4 - 8. We propose that the surface complex formed by EDTA is the controlling factor for the observed dissolution rate, with mononuclear EDTA surface complexes accelerating goethite dissolution compared to bi- or multinuclear complexes. These experimental results suggest that EDTA forms multinuclear complexes with goethite surfaces at pH values greater than or equal to 6 and mononuclear complexes with goethite surfaces at pH values < 6. Dissolution results show that when the oxyanion and the EDTA are present in the system at concentrations nearly equaling the surface sites available for adsorption, the oxyanion reduces the adsorption of EDTA and inhibits dissolution over the pH range of 4 - 8. However, a different mechanism occurs at pH values greater than or equal to 6 when the oxyanion is present at 0.1 mM. EDTA adsorbs but the number of carboxylic groups that can sorb to the surface is reduced causing the formation of mononuclear complexes. This shift from multi- to mononuclear surface complexes enhances the EDTA-promoted dissolution of goethite in the presence of the oxyanions compared to EDTA-promoted dissolution in their absence. / Master of Science

O interesse em utilizar terras raras para investigar propriedades e funções de sistemas bioquímicos tanto quanto de determinar substâncias biológicas tem crescido em diferentes áreas, incluindo biomarcadores em imunologia (fluoroimunoensaios). Atualmente, o uso de terras raras no diagnóstico de diversas doenças tem se tornado muito importante com o desenvolvimento de kits de diagnóstico. Como característica principal, as terras raras podem apresentar longo tempo de vida, fotoestabilidade e bandas de emissão finas e bem definidas na região do visível, demonstrando vantagens únicas quando comparadas a outras espécies luminescentes. O presente trabalho teve como objetivo sintetizar molibdatos de terras raras pelo método de coprecipitação, assim como caracterizá-los através de técnicas como: difração de raios X, espectroscopia do infravermelho, análise termogravimétrica, microscopia eletrônica de varredura, microscopia eletrônica de transmissão e estudos de luminescência. Nesse trabalho foram desenvolvidos três diferentes estudos de síntese: a influência da variação da velocidade do dispersor no momento da precipitação; a influência do tratamento térmico na estrutura, morfologia e propriedades luminescentes; e a influência da concentração do íon dopante nas propriedades estruturais e espectroscópicas. Outro passo importante desse trabalho foi o de aminofuncionalizar as nanopartículas utilizando um organosilano (APTES) para recobrir e estabelecer pontos para que essas partículas pudessem se ligar a espécies biológicas. Foi comprovado pelos resultados das caracterizações que esse processo foi eficiente e a incorporação da sílica foi bem sucedida. O Antígeno Específico da Próstata (PSA) foi então ligado às nanopartículas funcionalizadas para possibilitar o diagnóstico de câncer de próstata através de fluoroimunoensaios e dessa forma, níveis de detecção foram estabelecidos. / The interest in using rare earths to investigate the properties and functions of biochemical systems as well as to determinate biological substances has increased in several fields, including biomarkers in immunology (fluoroimmunoassays). Nowadays the use of lanthanides in the diagnosis of various diseases have become more important through the development of commercial diagnostic kits. As main feature, these rare earths can show a long lifetime, photostability and emission bands of atomic like behavior and well defined, in the visible region, demonstrating unique advantages when compared to other luminescent species. The present work had as its goal to synthesize rare earth molybdates by the co-precipitation method as well as to characterize these materials by X-ray diffraction, near infrared spectroscopy, thermogravimetric analysis, scanning electronic microscopy, transmission electronic microscopy and luminescent studies. In this work, three different studied were developed: the influence of the vortex speed variation during co-precipitation in the structure of the final product, morphology and luminescence properties; the influence of the annealing temperature also in the structure, morphology and luminescence properties; and the influence of concentration of the doping in the luminescence properties. Another important step of this work was the functionalization of nanoparticles using an organosilane (APTES) to coat and establish points for binding the particles to biological species. It was proved that this process was very efficient by the characterization results and the silica incorporation was well succeeded. Specific prostatic cancer (PSA) was then linked to the functionalized nanoparticles to diagnostic prostatic cancer by fluoroimmunoassay and levels for detection were established.

Emission of odorous and gaseous compounds such as hydrogen sulphide (H2S) from livestock facilities can be a major impediment to its daily operations and potential expansion. Occupational and environmental concerns require the control of H2S emissions. A treatment approach used in the oil industry in which nitrite and/or molybdate are used as metabolic inhibitors to control the production of H2S in oil reservoirs was shown to be effective in controlling H2S emissions from swine manure.<p> The addition of nitrite and molybdate to swine manure was investigated in closed laboratory scale systems and then evaluated in semi-pilot scale open systems and in specifically designed chambers aiming to simulate an actual swine barn. The effect of manure age (extent of storage) on H2S emissions and the levels of nitrite and molybdate required for effective control of these emissions were assessed. Laboratory scale tests showed that emission of H2S was dependent on manure age. Fresh manure emitted the highest level of H2S and the level of emission decreased as manure age (1-6 months) increased. With fresh 1, 3, and 6-month old manures average H2S concentration in the headspace gas of the closed systems were 4856b460, 3431b208, 1037b98 ppm, and non-detectable (<0.4 ppm), respectively. This translated to lower levels of nitrite or molybdate required to control H2S emission with increase in manure age. When compared to molybdate, the addition of nitrite initially led to lower levels of H2S but its effect was only temporary and not as persistent as molybdate. In the semi-pilot and room scale tests H2S levels emitted from untreated fresh manure (831¡Ó26 ppm and 88.4 ppm, respectively), were significantly lower than those observed in the laboratory system (4856¡Ó460 ppm). Moreover, the levels of molybdate required to control the emission of H2S were much lower in both the semi-pilot system and in the room scale chamber than in the closed system (0.1-0.25 mM as opposed to 2 mM).<p> Small scale land application of manure treated with 0.1 mM molybdate did not raise the level of molybdenum in the soil that could cause potential toxicity to plants and animals. No major differences in the nutrient properties of the soils exposed to the treated and untreated manure were observed. Finally, a preliminary feasibility study of this treatment approach showed that the cost associated with this control approach was less than 1% of the total production cost.

Emission of odorous and gaseous compounds such as hydrogen sulphide (H2S) from livestock facilities can be a major impediment to its daily operations and potential expansion. Occupational and environmental concerns require the control of H2S emissions. A treatment approach used in the oil industry in which nitrite and/or molybdate are used as metabolic inhibitors to control the production of H2S in oil reservoirs was shown to be effective in controlling H2S emissions from swine manure.<p> The addition of nitrite and molybdate to swine manure was investigated in closed laboratory scale systems and then evaluated in semi-pilot scale open systems and in specifically designed chambers aiming to simulate an actual swine barn. The effect of manure age (extent of storage) on H2S emissions and the levels of nitrite and molybdate required for effective control of these emissions were assessed. Laboratory scale tests showed that emission of H2S was dependent on manure age. Fresh manure emitted the highest level of H2S and the level of emission decreased as manure age (1-6 months) increased. With fresh 1, 3, and 6-month old manures average H2S concentration in the headspace gas of the closed systems were 4856b460, 3431b208, 1037b98 ppm, and non-detectable (<0.4 ppm), respectively. This translated to lower levels of nitrite or molybdate required to control H2S emission with increase in manure age. When compared to molybdate, the addition of nitrite initially led to lower levels of H2S but its effect was only temporary and not as persistent as molybdate. In the semi-pilot and room scale tests H2S levels emitted from untreated fresh manure (831¡Ó26 ppm and 88.4 ppm, respectively), were significantly lower than those observed in the laboratory system (4856¡Ó460 ppm). Moreover, the levels of molybdate required to control the emission of H2S were much lower in both the semi-pilot system and in the room scale chamber than in the closed system (0.1-0.25 mM as opposed to 2 mM).<p> Small scale land application of manure treated with 0.1 mM molybdate did not raise the level of molybdenum in the soil that could cause potential toxicity to plants and animals. No major differences in the nutrient properties of the soils exposed to the treated and untreated manure were observed. Finally, a preliminary feasibility study of this treatment approach showed that the cost associated with this control approach was less than 1% of the total production cost.

Thesis (Ph. D.)--Columbia University, 1937. / Vita. Bibliography: p. 20.

O interesse em utilizar terras raras para investigar propriedades e funções de sistemas bioquímicos tanto quanto de determinar substâncias biológicas tem crescido em diferentes áreas, incluindo biomarcadores em imunologia (fluoroimunoensaios). Atualmente, o uso de terras raras no diagnóstico de diversas doenças tem se tornado muito importante com o desenvolvimento de kits de diagnóstico. Como característica principal, as terras raras podem apresentar longo tempo de vida, fotoestabilidade e bandas de emissão finas e bem definidas na região do visível, demonstrando vantagens únicas quando comparadas a outras espécies luminescentes. O presente trabalho teve como objetivo sintetizar molibdatos de terras raras pelo método de coprecipitação, assim como caracterizá-los através de técnicas como: difração de raios X, espectroscopia do infravermelho, análise termogravimétrica, microscopia eletrônica de varredura, microscopia eletrônica de transmissão e estudos de luminescência. Nesse trabalho foram desenvolvidos três diferentes estudos de síntese: a influência da variação da velocidade do dispersor no momento da precipitação; a influência do tratamento térmico na estrutura, morfologia e propriedades luminescentes; e a influência da concentração do íon dopante nas propriedades estruturais e espectroscópicas. Outro passo importante desse trabalho foi o de aminofuncionalizar as nanopartículas utilizando um organosilano (APTES) para recobrir e estabelecer pontos para que essas partículas pudessem se ligar a espécies biológicas. Foi comprovado pelos resultados das caracterizações que esse processo foi eficiente e a incorporação da sílica foi bem sucedida. O Antígeno Específico da Próstata (PSA) foi então ligado às nanopartículas funcionalizadas para possibilitar o diagnóstico de câncer de próstata através de fluoroimunoensaios e dessa forma, níveis de detecção foram estabelecidos. / The interest in using rare earths to investigate the properties and functions of biochemical systems as well as to determinate biological substances has increased in several fields, including biomarkers in immunology (fluoroimmunoassays). Nowadays the use of lanthanides in the diagnosis of various diseases have become more important through the development of commercial diagnostic kits. As main feature, these rare earths can show a long lifetime, photostability and emission bands of atomic like behavior and well defined, in the visible region, demonstrating unique advantages when compared to other luminescent species. The present work had as its goal to synthesize rare earth molybdates by the co-precipitation method as well as to characterize these materials by X-ray diffraction, near infrared spectroscopy, thermogravimetric analysis, scanning electronic microscopy, transmission electronic microscopy and luminescent studies. In this work, three different studied were developed: the influence of the vortex speed variation during co-precipitation in the structure of the final product, morphology and luminescence properties; the influence of the annealing temperature also in the structure, morphology and luminescence properties; and the influence of concentration of the doping in the luminescence properties. Another important step of this work was the functionalization of nanoparticles using an organosilane (APTES) to coat and establish points for binding the particles to biological species. It was proved that this process was very efficient by the characterization results and the silica incorporation was well succeeded. Specific prostatic cancer (PSA) was then linked to the functionalized nanoparticles to diagnostic prostatic cancer by fluoroimmunoassay and levels for detection were established.

In der vorliegenden Arbeit wurden Lanthanoidmolybdate der allgemeinen Zusammensetzung Ln2MoO6, Ln2Mo2O9, Ln2Mo3O12, MLnMo2O8 (Ln= La, Pr-Lu und Y; M = Li-Cs) bezüglich ihrer kristallographischen sowie spektroskopischen Eigenschaften untersucht. Die Darstellung dieser Verbindungen erfolgte über Festkörperreaktionen bei Temperaturen zwischen 800 und 1000°C. In den Molybdat-Wirtsgittern mit Ln = La bzw. Ln = Gd wurden Lanthan bzw. Gadolinium in Abstufungen von 10, 30, 50, 75 und 100% durch trivalentes Europium substituiert und daraufhin mittels Lumineszenzspektroskopie eine Anwendung in pcLEDs evaluiert. Als herausragend erwies sich das System LiLnMo2O8 (Ln = La, Pr-Lu und Y). In diesem tetragonalen Wirtsgitter lassen sich alle Lanthanoidionen unabhängig vom Ionenradius miteinander kombinieren, ohne dass es zu einer Phasenumwandlung kommt. Somit kann eine Vielzahl von interessanten optischen Materialien entwickelt werden. Als geeigneter LED-Leuchtstoff wurde LiLa1-xEuxMo2O8 hergestellt und auf seine optischen Eigenschaften hin untersucht. Dieses Wirtsgitter zeigt auch bei einer vollständigen Substitution von Lanthan durch Europium keine Löschung der Lumineszenz. Durch Optimierung der Synthesebedingungen konnte mit LiEuMo2O8 bei Anregung mit 465 nm reproduzierbar eine Quantenausbeute von 100% erreicht werden. Das Lumenäquivalent ist mit 280 lm/W für eine Leuchtstoffanwendung ausreichend hoch.

Inhibitors used as dopant anions in polymer films are responsible for the anticorrosion behaviour of polypyrrole (Ppy). Ppy film doped with MoO42- and TiF62- showed the role of anions in corrosion protection of iron. Ppy doped with 3-nitro salicylate was used for zinc protection. The results of XPS revealed that molybdate exist in two types: [MoO4]2- (62%) and [Mo7O24]6- (28%). Electrochemical Impedance Spectroscopy (EIS) has indicated the change of the resistance RPM and the capacitance CPM of the Ppy film during reduction. Electrochemical Quartz Crystal Microbalance (EQCM) has shown: the mass of the Ppy film decreased in the cathodic region and increased in the anodic region. The anion flux was also observed in Scanning Kelvinprobe (SKP) and X-ray Photoelectron Spectroscopy (XPS) experiments. The release behaviour of molybdate anions depends much on the size of cations in the electrolyte. TiF62- anions has shown good inhibitor properties. However, the mechanism of this action is not yet known. 3-nitro salicylate (3-nisa) was used as inhibitor dopant for zinc in this work. Ppy film could be formed on Zn without any special pretreatment. The dissolution of Zn decreased dramatically in the presence of 3-nisa. The application of Ppy/metal inorganic composites in corrosion protection for mild steel and galvanised steel may be a better selection. Mixture of core-shell particles with matrix polymer was used as primer for protective coatings.

Inhibitors used as dopant anions in polymer films are responsible for the anticorrosion behaviour of polypyrrole (Ppy). Ppy film doped with MoO42- and TiF62- showed the role of anions in corrosion protection of iron. Ppy doped with 3-nitro salicylate was used for zinc protection. The results of XPS revealed that molybdate exist in two types: [MoO4]2- (62%) and [Mo7O24]6- (28%). Electrochemical Impedance Spectroscopy (EIS) has indicated the change of the resistance RPM and the capacitance CPM of the Ppy film during reduction. Electrochemical Quartz Crystal Microbalance (EQCM) has shown: the mass of the Ppy film decreased in the cathodic region and increased in the anodic region. The anion flux was also observed in Scanning Kelvinprobe (SKP) and X-ray Photoelectron Spectroscopy (XPS) experiments. The release behaviour of molybdate anions depends much on the size of cations in the electrolyte. TiF62- anions has shown good inhibitor properties. However, the mechanism of this action is not yet known. 3-nitro salicylate (3-nisa) was used as inhibitor dopant for zinc in this work. Ppy film could be formed on Zn without any special pretreatment. The dissolution of Zn decreased dramatically in the presence of 3-nisa. The application of Ppy/metal inorganic composites in corrosion protection for mild steel and galvanised steel may be a better selection. Mixture of core-shell particles with matrix polymer was used as primer for protective coatings.