Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This work elaborates on the determination of crystal and molecular structures of four pro-ligands, emphasizing bis(triazenes), triazene 1-oxide and a new class of bis(triazenes) macrocyclic, and eight complexes involving Cu+, Cu2 +, Ni2 + and K+. Pro-ligands triazenes 1-oxide are relatively small and simple molecules. When they are deprotonated they presen a high ability to form supramolecular assemblies, either because they are planar and facilitate the metal-metal approach and the formation of π···π interactions _ as in the case of complex (2) _, or because they have substituents with capacity of act as agent of secondary complexation forming polycationic structures _ as in the case of complex (3). Pro-ligand bis(triazenes) are double agents of complexation. The bis(triazene) (4) complexed Copper(I) forming a binuclear complex (5). The same ligand also led to binuclear complexes of Copper(II) through the chelate and macrocyclic effect, forming two types of crystal structures, one non-centrosymmetric (6), the other centrosymmetric (7). The pro-ligand bis(triazene) macrocyclic (8) has a cavity with ideal size for the complexation of transition metals, resulting, for example, in complex (9) with the cation Nickel(II). The ligand in this complex has substituents in para position. These substituents, two pyridine molecules (in the coordination sphere of the metal) and two pyridine molecules (as solvate of crystallization) form weak electrostatic interactions in the supramolecular arrangement. The bis(triazene) macrocyclic (10) has a central cavity larger than the bis(triazene) macrocyclic (8), allowing the complexation of larger molecules or ions. The analysis by X-ray diffraction on single crystal for the compound (10) revealed the presence of disordered water molecules inside the cavity, forming a chain of water molecules perpendicular to the stacked molecules of (10). When the compound (10) is deprotonated with a weak base such as pyridine, the deprotonation occurs partially, leading to a binuclear complex with Copper(II)-bridged μ2-OH (11). Two molecules of the ligand coordinate the two Copper(II) cations, and the coordination sphere is completed by two axial pyridine molecules. When the compound (10) is deprotonated with a strong base such as sodium or potassium ethanolate, the deprotonation occurs totally, leading to a binuclear conmplex with Copper(II)-bridged μ2-OCH2CH3 (12). One molecule ligand coordinates two Copper(II) cations and the coordination sphere is also supplemented by two axial pyridine molecules. The synthesis of a new class of macrocyclic triazenes has been successfully performed as well as the synthesis of their metallic complexes. The characterization of their structures and supramolecular assemblies was performed using the analysis by X-ray diffraction on single crystal and other secondary methods. / Este trabalho apresenta as determinações das estruturas cristalinas/moleculares de quatro pró-ligantes, enfatizando bis(triazenos), triazeno 1-óxido e a nova classe de bis(triazenos) macrocíclicos, e oito complexos envolvendo os cátions Cu+, Cu2+, Ni2+ e K+. Pró-ligantes triazenos 1-óxido são moléculas relativamente pequenas e simples, que quando desprotonadas apresentam elevada capacidade de formação de arranjos supramoleculares, sejam pelo fato de serem planares e facilitarem a aproximação metal-metal e a formação de interações π···π, como no caso do complexo (2), ou pelo fato de apresentarem substituintes capazes de atuarem como complexantes secundários, formando estruturas policatiônicas complexas, como no caso do complexo (3). Pró-ligantes bis(triazenos) são agentes duplos de complexação. O bis(triazeno) (4) mostrou-se capaz de complexar o íon cobre(I) formando um complexo binuclear (5). O mesmo ligante, ainda, originou complexos binucleares de cobre(II), através do efeito quelato e macrocíclico, formando dois tipos de estruturas cristalinas, uma não-centrossimétrica (6) e outra centrossimétrica (7). O pró-ligante bis(triazeno) macrocíclico (8) apresenta uma cavidade com tamanho ideal para a complexação de metais de transição, originando, por exemplo, o complexo (9) com o cátion níquel(II). O ligante neste complexo apresenta substituintes em posição para e estes subtituintes, adicionados às moléculas de piridina que completam a esfera de coordenação do metal e às moléculas de piridina como solvato de cristalização, formam o arranjo supramolecular, através de interações eletrostáticas fracas. O pró-ligante bis(triazeno) macrocíclico (10) apresenta uma cavidade central maior que o pró-ligante bis(triazeno) macrocíclico (8), possibilitando a complexação de moléculas ou cátions maiores. A difração de raios-x em monocristal de (10) revelou a presença de moléculas de água desordenadas no interior da cavidade, formando uma cadeia perpendicular às moléculas empacotadas do pró-ligante macrocíclico. Quando o composto (10) é desprotonado com base fraca, como piridina, a desprotonação ocorre de maneira parcial, originando um complexo binuclear de cobre(II) unido por pontes μ2-OH (11), onde duas moléculas de ligante coordenam os dois íons cobre(II) e a esfera de coordenação quadrática é completada por duas moléculas de piridina axiais. Quando o composto (10) é desprotonado com base forte, como etóxido de sódio ou potássio, a desprotonação ocorre de maneira total, originando um complexo binuclear de cobre(II) unido por pontes μ2-OCH2CH3 (12), onde uma molécula de ligante coordena os dois íons cobre(II) e a esfera de coordenação quadrática também é completada por duas moléculas de piridina axiais. A síntese de mais representantes da nova classe de triazenos macrocíclicos foi realizada com sucesso neste trabalho, bem como a síntese de complexos, envolvendo triazenidos macrocíclicos. A caracterização de suas estruturas e arranjos supramoleculares foi realizada através de difração de raios-x em monocristal e outros métodos secundários.

Orientadores: Roberto Perez Xavier, Lena Virginia Soares Monteiro / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociencias / Made available in DSpace on 2018-08-14T22:53:15Z (GMT). No. of bitstreams: 1 Torresi_Ignacio_M.pdf: 10387814 bytes, checksum: 10ae1f36fa8d66f6046d5f1bb6d6a4aa (MD5) Previous issue date: 2009 / Resumo: O depósito de óxido de ferro-cobre-ouro (IOCG) Alvo 118 (170 Mt @ 1,0 wt% Cu, 0,3 g/t Au), junto aos depósitos de classe mundial de Sossego e Cristalino, situam-se no setor sul da Província Mineral de Carajás (PMC) alinhados e uma zona de cisalhamento subvertical regional, de direção WNW-ESE, e 60 km de extensão, próximo ao contato do Supergrupo Itacaiunas, uma sequência metavulcano-sedimentar (~2,76 Ga), com o embasamento arqueano (Complexo Xingu; ~3,0 Ga). A mineralização de Cu-Au no deposito Alvo118 e hospedada por rochas vulcanicas máficas e intermediarias, corpos de granitos e gabbros, que foram sujeitos a seguinte sequência de alteração hidrotermal em direção ao minério de Cu: (1) alteração sódica representada por albita e escapolita, o que indica circulação de fluidos quentes (>500°C) e salinos; (2) alteração potássica dominada pela presença de biotita e k-feldspato, respectivamente, nas rochas máficas e intermediarias, acompanhada de formação de magnetita e silicificação; (3) alteração a clorita, espacialmente associada brechas quartzo-carbonaticas mineralizadas a calcopirita e stockworks de veios que normalmente apresentam estruturas de preenchimento de espaço; (4) alteração a quartzo-sericita tardia a mineralizacao. A assembléia mineral da mineralizacao e dominada por calcopirita (80%), acompanhado de bornita (10%), magnetita (10%), hematita (10%), e traços de teluretos de Au-Ag, galena e cassiterita. Diferente de outros depósitos do tipo IOCG da PMC, onde ETRL estão presentes em apatita, allanita e monazita, no Alvo 118 o enriquecimento e em ETRP. Neste deposito os ETRP estão concentrados principalmente em apatite e em um mineral pobre em alumínio, um silicato de Be-B-ETRP do grupo da gadolinite, que nunca foi descrita em qualquer deposito do tipo IOCG do mundo. Estudos de inclusões fluidas em quartzo e calcite apontam pra um regime de fluidos, em que soluções hipersalinas e quentes, representada por inclusões trifásicas, fossem progressivamente esfriadas e diluídas por fluidos de baixa salinidade, representada por inclusões bifásicas, que dominam na mineralizacao do Alvo 118. Valores de d18OH2O em equilíbrio com calcita (-1.9¿ a 10.7¿ a 300°C) sugerem forte interação entre os fluidos mineralizantes e as rochas hospedeiras, como também prolongada mistura com fluidos meteóricos. A composição de d34S em calcopirita (5.1¿ a 6.3¿) difere daquela de fonte mantélica/magmática, reforçando a possibilidade de fontes de enxofre mais pesado (sulfatos de evaporitos?) para os sulfetos da brecha e dos veios mineralizados. A alteração sódica de alta temperatura, a sobreposição de alteração potássica e a alteração a clorita proximal, a brecha de quartzo-carbonatica mineralizada e os valores de d18O indicam que o Alvo 118 e um sistema IOCG que evoluiu em níveis estruturais superiores, nível crustal raso, envolvendo o influxo de águas meteóricas. / Abstract: The Alvo 118 iron oxide-copper-gold (IOCG) deposit (170 Mt @ 1,0 wt% Cu, 0,3 g/t Au), together with the world-class Sossego and Cristalino deposits, lie in the southern sector of the Carajas Mineral Province (CMP) along a steeply-dipping, WNW-ESE-striking, 60 km-long shear zone, close to the contact of the Itacaiunas Supergroup metavolcano-sedimentary sequence (~2,76 Ga) and the basement (Xingu Complex; ~3,0 Ga). The Cu-Au mineralization at the Alvo 118 is hosted by mafic and felsic metavolcanic rocks and crosscutting granitoid and gabbro bodies that have been subjected to the following hydrothermal alteration sequence towards the ore zones: (1) sodic alteration represented by albite and scapolite, indicating the circulation of hot (>500°C) and highly saline fluids; (2) potassium alteration dominated by biotite or Kfeldspar, respectively, in mafic and felsic volcanic and intrusive rocks, accompanied by the formation of magnetite and silicification; (3) chlorite alteration spatially associated with carbonate-quartz ore breccia and vein stockworks that commonly display open-space filling textures; (4) local post-ore quartz-sericite alteration. The ore assemblage is dominated by chalcopyrite (80%), accompanied by bornite (10%), magnetite (10%), hematite (10%), and traces of Au-Ag tellurides, galena and cassiterite. Dissimilar from other IOCG deposits of the CMP where LREEs are commonly enriched in apatite, allanite and monazite, the Alvo 118 ore displays enrichments of HREEs. In this deposit the HREEs are mainly concentrated in apatite and in an Al-poor, Be-B-HREE silicate of the gadolinite group which has never been reported in IOCG systems worldwide. Fluid inclusion studies in quartz and calcite point to a fluid regime in which hot brine solutions, represented by < 10 vol.% of salt-bearing aqueous inclusions, were progressively cooled and diluted by lower temperature, low-salinity (< 10 wt% NaCl eq.) aqueous fluids defined by two-phase aqueous inclusions, by far the dominant type. d18OH2O values in equilibrium with calcite (- 1.9¿ to 10.7¿ at 300°C) suggest strong interaction between ore fluids and the host rocks, as well as prolonged mixing with meteoric fluids. The d34S composition of chalcopyrite (5.1¿ to 6.3¿) differs from a mantle/magmatic source adding the possibility of heavier sulfur sources (e.g., evaporite sulfate?) for the ore breccia and vein sulfides. The restricted high temperature sodic alteration, the pervasive overprinting of the potassic alteration minerals (biotite and K-feldspar) by chlorite proximal to the ore zones, quartz-calcite-chlorite ore breccias/veins with open-space filling textures in brittle structures, and the d18O data collectively indicate that the Alvo 118 IOCG system developed at structurally high levels and experienced the influx of evolved meteoric water. / Mestrado / Mestre em Geociências

Orientadores: Lena Virginia Soares Monteiro , Roberto Perez Xavier / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociências / Made available in DSpace on 2018-08-15T15:13:25Z (GMT). No. of bitstreams: 1 Moreto_CarolinaPenteadoNatividade_M.pdf: 6364154 bytes, checksum: 08d26b0642844f0ebe0c97e4f6816d34 (MD5) Previous issue date: 2010 / Resumo: O depósito de óxido de ferro-cobre-ouro Bacaba, situado no Cinturão de Cisalhamento Itacaiúnas, Província Mineral de Carajás, representa um alvo satélite do depósito de classe mundial Sossego, e possivelmente também representa as porções distais e profundas do mesmo sistema hidrotermal. O depósito Bacaba localiza-se ao longo de uma zona de cisalhamento com direção WNW-ESE que define o contato entre o embasamento, representado pelo Complexo Xingu (ca. 3,0 Ga), e a unidade metavulcano-sedimentar do Supergrupo Itacaiúnas (ca. 2,76 Ga). As principais rochas hospedeiras do minério no depósito Bacaba são representadas pelo Granito Serra Dourada, Tonalito Bacaba e por corpos gabróicos, que foram intensamente afetados por alterações hidrotermais sódica (albita-escapolita), potássica, clorítica e hidrolítica. Os dados de U-Pb LA-ICP-MS em zircão de uma amostra com alteração sódica do Granito Serra Dourada forneceram a idade de 2858 ± 30 Ma (MSWD = 9,7). Três amostras do Tonalito Bacaba, sendo uma com alteração potássica e duas com alteração potássica e mineralização de Cu-Au, forneceram idades em 2997,2 ± 4,7 Ma (MSWD = 1,15), 2993,1 ± 7,1 Ma (MSWD = 1,1) e 3004,7 ± 7,8 Ma (MSWD = 2,1), respectivamente. As idades em 2,86 e ca. 3,0 Ga são interpretadas como idade de cristalização do Granito Serra Dourada e do Tonalito Bacaba, respectivamente. As estruturas internas e morfologia dos cristais de zircão de ambas as rochas, observadas em imagens de catodoluminescência e de elétrons retro-espalhados, confirmam a ocorrência de processos de recristalização, que pode ser relacionado com episódios de hidrotermalismo e/ou deformação/metamorfismo que ocorreram na Província Mineral de Carajás. Contudo, esse (s) evento (s) não pode (puderam) ser datado (s) devido à ausência de abertura total do sistema isotópico U-Pb e ausência de cristais de zircão de origem hidrotermal.O Granito Serra Dourada e o Tonalito Bacaba são as rochas graníticas mais antigas até então reconhecidas no Cinturão de Cisalhamento Itacaiúnas. A presença dessas rochas tão antigas implica na existência de um importante magmatismo anterior à instalação da Bacia de Carajás (Supergrupo Itacaiúnas), e em uma história evolutiva mais complexa para o Cinturão de Cisalhamento Itacaiúnas. As similaridades petrográficas e geocronológicas dessas intrusivas félsicas do depósito Bacaba com suítes de rochas graníticas e tonalíticas reconhecidas no Terreno Granito-Greenstone Rio Maria, porção sul da Província Mineral de Carajás, implica na ocorrência de um magmatismo de ca. 3,0 e 2,86 Ga mais amplo e extenso. O Granito Serra Dourada e o Tonalito Bacaba não poderiam ser responsáveis pelo estabelecimento do sistema magmático-hidrotermal associado com a gênese do depósito Bacaba. Isso seria improvável porque outros depósitos com características similares são hospedados por unidades metavulcano-sedimentares mais novas (2,76 Ga). Nesse contexto, os depósitos de óxido de ferro-cobre-ouro do setor sul do Cinturão de Cisalhamento Itacaiúnas devem ser controlados principalmente por importantes descontinuidades crustais, como a zona de cisalhamento regional com direção WNW-ESE, ao invés de serem associados com um litotipo particular. Esses resultados indicam alto potencial de ocorrência de depósitos de óxido de ferro-cobre-ouro nas rochas mesoarqueanas do embasamento sob a Bacia de Carajás, particularmente aquelas cortadas por zonas de cisalhamento neoarqueanas. / Abstract: The Bacaba iron oxide-copper-gold deposit, situated in the Itacaiúnas Shear Belt, Carajás Mineral Province (Brazil), represents a satellite prospect of the world-class Sossego deposit, and might also represent a distal and deeper portion of the same or related hydrothermal system. The Bacaba deposit is located along a WNW-ESE-striking shear zone that defines the contact of the basement represented by the Xingu Complex (ca. 3.0 Ga) and the metavolcanosedimentary Itacaiúnas Supergroup (ca. 2.76 Ga). The main host rocks at Bacaba deposit comprise the Serra Dourada Granite, the Bacaba Tonalite and croscutting gabbro, which were intensely affected by sodic (albite-scapolite), potassic, chloritic and hydrolytic hydrothermal alterations. The U-Pb LA-ICP-MS data for zircon from sodic altered sample of the Serra Dourada Granite yielded an 2858 ± 30 Ma (MSWD = 9.7) age. Three samples from the Bacaba Tonalite, including one with potassic alteration and two with potassic alteration and Cu-Au mineralization rendered the 2997.2 ± 4.7 Ma (MSWD = 1.15), 2993.1 ± 7.1 Ma (MSWD = 1.1) and 3004.7 ± 7.8 Ma (MSWD = 2.1) ages, respectively. The 2.86 and ca. 3.0 Ga ages are interpreted as the igneous crystallization of the Serra Dourada Granite and the Bacaba Tonalite, respectively. The internal structures and external morphologies of zircon crystal from both rocks, observed in cathodoluminescence and backscattered electron images, attested the occurrence of zircon recrystallization, which could be related to hydrothermalism and/or deformation/metamorphism episodes that took place in the Carajás Mineral Province. However, the disturbing event (s) could not be dated due to the absence of the total resetting of the U-Pb system and hydrothermal crystallization of zircon. The 2.86 Ga Serra Dourada Granite and the ca. 3.0 Ga Bacaba Tonalite are the oldest granitic rocks so far recognized in the Itacaiúnas Shear Belt. The presence of such old rocks implies in the existence of an important magmatism before the Carajás Basin (Itacaiúnas Supergroup) deposition, and in a more complex evolutionary history for the Itacaiúnas Shear Belt. The petrographical and geochronological similarities of these felsic intrusions with granitic and tonalitic rock suites recognized in the Rio Maria granite-greenstone terrane, southern part of the Carajás Mineral Province, implies in a more widespread ca. 3.0 and 2.86 Ga magmatism in the province. The Serra Dourada Granite and the Bacaba Tonalite are interpreted not to be responsible for the genesis of the Bacaba deposit. This is likely because the Sossego and other deposits interpreted as part of the same hydrothermal system are hosted by younger ca. 2.76 Ga metavolcano-sedimentary units. On this context, the iron oxide-copper-gold deposit in the southern sector of the Itacaiúnas Shear Belt could be mainly controlled by important crustal discontinuities, such as the WNW-ESEstriking regional shear zone, rather than be associated with a particular rock type. These results expand the potentiality of occurrence of iron oxide-copper-gold deposits for the Mesoarchean basement rocks underlying the Carajás Basin, particularly those crosscut by Neoarchean shear zones. / Mestrado / Geologia e Recursos Naturais / Mestre em Geociências

O presente trabalho apresenta estudos espectrofotométricos relacionados à autoxidação dos complexos de Cu(II), Ni(II) e Co(II)/tetraglicina induzida por sulfito. Nossos estudos verificaram que a autoxidação de Cu(II)/tetraglicina (1,0x10-3 mol L-1) em pH = 9,0 (tampão borato) é afetada pela presença de traços de Ni(II) ou Co(II). Na ausência de Ni(II) ou Co(II), a reação é muito ineficiente e lenta com períodos de indução longos (aproximadamente 4 h). Ni(II) ou Co( II) em concentrações baixas ( 10-5 - 10-6 mol L-1) afetam significativamente a cinética: o período de indução diminui drasticamente (a menos de 2 s) e a formação de Cu(III) é fortemente acelerada com simultâneo aumento da eficiência da reação. A atividade catalítica e o sinergismo positivo de Co(II) e Ni(II) podem ser explicados pela oxidação mais rápida de Co(II) ou Ni(II)/tetraglicina pelo oxigênio dissolvido. O processo eletroquímico relacionado aos sistemas Cu(II)/Cu(III)/tetraglicina e Ni(II)/Ni(III)/tetraglicina são reversíveis, possibilitando monitorá-los adequadamente mediante o uso da técnica de eletrodo rotativo disco-anel. Entretanto, o sistema Co(II)/Co(III)/tetraglicina é irreversível. Esses estudos mostraram que as espécies de Cu(III) e Ni(III) geradas no eletrodo disco são instáveis nas condições experimentais empregadas. O efeito sinérgico positivo na presença de Ni(II) (que permitiu aumentar a sensibilidade) foi aproveitado para desenvolvimento de método espectrofotométrico e amperométrico simples e sensível para a determinação indireta de sulfito em meio aquoso. O método espectrofotométrico está baseado na medida de absorbância do complexo de Cu(III)/tetraglicina (gerado na presença de sulfito e traços de Ni(II)) em 365 nm. O método amperométrico em análise por injeção em fluxo baseia-se na medida de corrente (0,1 V vs Ag/AgCl) em função da concentração de Cu(III)/tetraglicina gerado quimicamente, na presença de sulfito e traços de Ni(II). Os métodos desenvolvidos foram empregados para a determinação de S(IV), em vinhos e sucos, após a sua extração da amostra acidificada, os resultados obtidos concordaram com aqueles obtidos pelo método iodométrico. / The present work presents spectrophotometric studies related to the sulfite induced autoxidation of Cu(II), Ni(II) and Co(II)/tetraglycine complexes. The sulfite induced autoxidação of Cu(II)/tetraglycine (1.0x10-3 mol L-1) at pH = 9.0 (borate buffer) is affected by the presence of small quantities of the Ni(II) or Co(II). In the absence of added nickel (II) or cobalt (II), the reaction is very inefficient and slow with one large induction period (about 4 h). Trace amounts of Ni(II) or Co(II) (10-5 - 10-6 M) affect the kinetic significantly: the induction period drastically decreases (less than 2 s) and the formation of Cu(III) is strongly accelerated. The effectiveness of Cu(III) formation becomes much higher. The catalytic activity and the positive synergism of Co(II) and Ni(II) may be explained by the faster oxidation of Co(II) or Ni(II)/tetraglycine complexes by dissolved oxygen. The electrochemistry of Cu(II)/Cu(III)/tetraglycine and Ni(II)/Ni(III)/tetraglycine systems are reversible, such as it was possible to monitor them by using the rotating ring-disk electrode technique. However, the Co(II)/Co(III)/tetraglycine system is irreversible. Those studies showed that the Cu(III) and Ni(III) species generated on the disk electrode are unstable in the employed experimental conditions. The positive sinergistic effect in the presence of Ni(II) (which allowed to increase the sensibility) was taken in advantage for development of one simple and sensitive spectrophotometric and amperometric method for indirect determination of sulfite in aqueous medium. The spectrophotometric method is based on the absorbance measurement of the Cu(III)/tetraglicyne complex (generated in the presence of sulfite and small quantities of Ni(II)) at 365 nm. The amperometric method by flow injection analysis is based on the current measurement (0.1 V vs Ag/AgCl) as function of Cu(III)/tetraglycine concentration chemically generated, in the presence of sulfite and Ni(II). The methods were employed for the determination of S(IV), in wines and juices, after its extraction from acidified samples and the results were in agreement with those obtained by the iodometric procedure.

Made available in DSpace on 2016-08-19T12:56:36Z (GMT). No. of bitstreams: 1 MIRELA GHISI.pdf: 1324849 bytes, checksum: 5d9ca5c5a49c366f3bf4959e2e942a14 (MD5) Previous issue date: 2011-05-16 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / The metals content in biodiesel is directly related with the raw material used and also with the utilized biodiesel production method. In this work, an evaluation of the main metals present in biodiesel samples from different sources was done. The qualitative analysis of the metal content was assessed using the Inductively Coupled Plasma Mass Spectrometry technique after sample digestion in microwave oven. The main metals identified in the analyzed biodiesel samples were Al, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Sr and Zn. Metals like Ag, As, Ba, Cd, Co, Tl and V have not significant presence in the samples. Among these, Cu and Fe were selected due to their relevance and importance in oxidative process of biodiesel, to the development of an analytical methodology to be used in the determination by Electrothermal Atomic Absorption Spectrometry, and also evaluate the effect of these metals over the oxidative stability of the soy biodiesel. The samples were prepared with tetramethylammonium hydroxide (TMAH), and the pyrolysis and atomization temperatures were optimized pyrolysis and atomization curves. The high pyrolysis temperature adopted, 1000 oC, certainly minimized potential interferences, but calibration had to be carried out with aqueous standard solutions in the presence of the TMAH. The detection limits in the sample (3s, n=10), were quite low 15 ng g-1 and 24 ng g-1 for Cu and Fe, respectively. Seven biodiesel samples, produced from different raw materials, including vegetable seed, waste frying oil and animal fat were analyzed. Accuracy was validated by applying the recovery test (recoveries from 105% to 120%) and through comparison with the obtained results by High Resolution Continuum Source Electrothermal Atomic Absorption Spectrometry. The precision, expressed by the relative standard deviation, was better than 3% for Cu and than 7% for Fe. Copper could be quantified in two and Fe in three of the seven samples. The biodiesel sample from fodder turnip was especially rich in the analytes in comparison to the other samples. The influence of metals Cu and Fe on soy biodiesel oxidative stability was evaluated by Rancimat method through induction period, according with the Standard EN 14112. The metals Cu2+ and Fe3+ were added to the biodiesel samples in the form of theirs salts, and different storage times of the samples were evaluated. Due to the catalytic behaviour of these metals, the oxidative stability of the samples was affected, even under low metal concentrations. Compared to Cu2+, the effect over the biodiesel stability was higher when Fe3+ was added. / A presença de metais no biodiesel está diretamente relacionada com a matéria-prima utilizada e também com o processo utilizado para a obtenção do biodiesel. Neste trabalho realizou-se uma avaliação dos principais metais presentes em amostras de biodiesel provenientes de diferentes fontes. A análise semi-quantitativa nas amostras de biodiesel foi realizada utilizando a técnica de Espectrometria de Massa com Plasma Indutivamente Acoplado após a digestão das amostras em micro-ondas. Os principais metais identificados nas amostras de biodiesel analisadas são Al, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Sr e Zn. Metais como Ag, As, Ba, Cd, Co, Tl e V não estão presentes em concentrações significativas nessas amostras. Em função de sua relevância e importância em processos oxidativos do biodiesel, selecionou-se Cu e Fe para o desenvolvimento de uma metodologia analítica para a determinação destes por Espectrometria de Absorção Atômica com Atomização Eletrotérmica e também a avaliação do efeito destes metais sobre a estabilidade oxidativa do biodiesel de soja. As amostras foram preparadas com hidróxido de tetrametilamônio (TMAH), e as temperaturas de pirólise e atomização foram otimizadas através de curvas de pirólise e atomização. A alta temperatura de pirólise adotada, 1000 oC, certamente ajudou a minimizar possíveis interferências; porém, a calibração teve de ser realizada com padrões aquosos na presença de TMAH. Os limites de detecção (3s, n = 10), na amostra, foram baixos, 15 ng g-1 e 24 ng g-1 para Cu e Fe, respectivamente. Sete amostras de biodiesel, produzidas de diferentes matérias-primas, incluindo óleos vegetais, óleo de fritura e gordura animal foram analisadas. A exatidão foi avaliada através do teste de recuperação (recuperações de 105% a 120%) e através da comparação com os resultados obtidos por Espectrometria de Absorção Atômica de Alta Resolução com Fonte Contínua e Atomização Eletrotérmica. A precisão, expressa pelo desvio padrão relativo foi melhor que 3% para Cu e que 7% para Fe. Cobre pôde ser quantificado em duas e Fe em três das sete amostras. A amostra de biodiesel proveniente do nabo forrageiro era especialmente rica nos analitos comparada às outras amostras. A influência dos metais Cu e Fe sobre a estabilidade oxidativa do biodiesel de soja foi avaliada pelo método Rancimat através do período de indução, de acordo com a Norma EN 14112. Os metais Cu2+ e Fe3+ foram adicionados nas amostras de biodiesel na forma de seus sais, e foram avaliados diferentes tempos de armazenamento das amostras. Devido ao efeito catalítico destes metais, a estabilidade oxidativa das amostras analisadas foi reduzida mesmo na presença de baixas concentrações dos metais. O efeito do Fe3+ sobre a estabilidade do biodiesel foi significativamente maior quando comparado ao Cu2+.

La radiographie X synchrotron ou avec une source microfocus a été appliquée pour étudier différents phénomènes dépendants du temps en relation avec la solidification directionnelle d'alliages Al-Cu. Les effets de la gravité ont été étudiés par comparaison d'expériences sur Terre et en microgravité dans le cadre du projet ESA-MAP XRMON. Les mouvements des fragments sont le sujet majeur de notre étude. Sur Terre, le mouvement des fragments est imposé par la poussée d'Archimède, avec une forte influence des effets de paroi et de la morphologie du fragment, alors qu'en microgravité, la force motrice pour le mouvement des fragments est l'écoulement du fluide interdendritique induit par la contraction du solide. L'effet d'un champ magnétique permanent sur la solidification des grains équiaxes dans un gradient de température a été également étudié. Nous avons montré qu'un couplage entre le gradient de température et le champ magnétique donne naissance à une force Thermo-électromagnétique qui agit sur les grains solides. Une bonne description a été obtenue en utilisant un modèle analytique pour une particule sphérique. Enfin, nous avons étudié l'évolution d'une zone pâteuse dans un gradient de température fixe. Trois régimes successifs ont été identifiés, suivant l'intensité de la diffusion du soluté dans la zone pâteuse et dans le bain fondu. L'analyse quantitative des radiographies par traitement d'image a clarifié le rôle de chaque phénomène de diffusion (TGZM, fermeture des canaux, murissement et diffusion du soluté dans le bain fondu). / X-ray radiography with synchrotron and microfocus sources was applied to investigate various time-dependent phenomena related to directional solidification of Al-Cu alloys. Gravity effects were investigated by a comparative study of ground and microgravity experiments in the framework of ESA-MAP XRMON project. Fragment motion was the major subject of our investigation. On Earth, fragmentation motion was imposed by buoyancy, with a strong dependency on wall influence and fragment morphology, whereas in microgravity conditions, the driving force for fragment motion is the interdendritic fluid flow induced by the solid shrinkage. The effect of a permanent magnetic field on the solidification of equiaxed grains in a temperature gradient was also studied. We have shown that a coupling between the temperature gradient and the magnetic field gives birth to a Thermo-Electro-Magnetic force that acts on the solid grains. A good description was obtained by using an analytical model for a spherical particle. Finally we studied the evolution of the mushy zone in a fixed temperature gradient. Three successive regimes were identified, depending on the relative magnitude of solute diffusion in the mushy zone and in the bulk liquid. Quantitative analysis of radiographs by image processing enlightened the role of each diffusion phenomena (TGZM, channel closure, coarsening and solute diffusion in the bulk liquid).

Nous étudions la fragilisation par l'hydrogène de l'alliage d'aluminium 7108. Une technique expérimentale spécifique a été développée : Un pré-chargement en hydrogène des échantillons, à travers un dépôt de nickel de quelques dizaines de microns, qui empêche la dissolution du substrat d'aluminium, est utilisé. Il permet la comparaison de la résistance à la fragilisation de différentes microstructures modèles. Nous étudions l'effet du traitement thermique et de la précipitation sur la sensibilité à l'hydrogène pour des vitesses de déformation macroscopiques imposées variables. Différents modes de rupture sont observés ainsi que des transitions entre eux. Au moyen de simulations numériques à l'échelle mésoscopique, l'effet de taille des précipités intergranulaires pré-fragilisés sur la ténacité des joints de grains est estimé, en utilisant un modèle de zone cohésive. Nous analysons la compétition entre la diffusion de l'hydrogène vers la pointe de la fissure et la vitesse de fissuration par un couplage mécanique - diffusion basé sur la diffusion de l'hydrogène assistée par la contrainte hydrostatique. Une vitesse critique au-delà de laquelle l'hydrogène ne peut plus suivre la fissure, est mise en évidence. L'influence de la microstructure du joint de grains sur cette vitesse est analysée. La valeur est comparée à une estimation des vitesses de propagation expérimentales obtenues pour différentes vitesses de déformation macroscopiques. Nous analysons l'effet du piégeage de l'hydrogène par les précipités intergranulaires et la désorption sur la répartition de l'hydrogène le long du joint de grains en imposant un flux au niveau de l'interface précipités - matrice. / We study the hydrogen embrittlement of the 7108 aluminum alloy. A specific experimental technique was developed : A hydrogen pre-charging, through few tens of microns of deposit of nickel, which prevents the dissolution of the aluminum substrate is used. It allows a comparison of the resistance to embrittlement of different model microstructures. We study the effect of heat treatment and intergranular precipitation on the susceptibility to hydrogen embrittlement for several macroscopic strain rates. Different failure modes and transitions between them are observed. Through numerical simulations, at the mesoscopic scale, the effect of the size of pre-weakened intergranular precipitates on the grain boundary toughness is estimated using a cohesive zone model. We further analyze the competition between the hydrogen diffusion toward the crack tip and crack velocity. For this purpose, a mechanical – diffusion coupling based on the hydrogen diffusion assisted by hydrostatic stress is elaborated. A critical crack velocity, beyond which hydrogen can no longer follow the crack, is highlighted. The influence of the grain boundary microstructure on this critical crack velocity is evaluated and its value is compared with an estimate of velocities obtained for different experimental macroscopic strain rates. We analyze the effect of hydrogen trapping by intergranular precipitates and hydrogen desorption by imposing a flux at the precipitates – matrix interfaces.

Ce travail vise à comprendre l’évolution de la texture cristallographique et l’anisotropie du comportement mécanique après laminage à chaud et traitements thermiques d’un Al-Cu-Li 2050 et d’un Al-Zn-Mg-Cu 7050, et expliquer leurs différences. La texture est analysée par EBSD et RX après des essais de compression plane à chaud et après des laminages à chaud industriels. L’anisotropie est étudiée sur des tôles fortes industrielles après différents détensionnements et dans différents états microstructuraux par des essais de traction à 0°, 45° et 90° par rapport à DL. Enfin, nous comparons nos mesures à des résultats simulés par des modèles de plasticité cristalline (modèles de Taylor). Il est montré que, déformés dans des conditions identiques, les deux alliages développent les mêmes textures de laminage jusqu'à une déformation de 2.6. La présence de 1% massique de Li n’est à priori pas responsable d’une texture particulière. En revanche la température de laminage, qui est généralement plus élevée pour les Al-Cu-Li que pour les Al-Zn-Mg-Cu, a un impact important aux grandes déformations, notamment en favorisant la composante Laiton {110}<112>. L'anisotropie d'une tôle laminée de 2050 est pour une large part due à la texture cristallographique. Elle augmente quand un détensionnement est effectué par traction dans la direction DL et diminue quand il est effectué à 45°/DL. La précipitation durcissante, composée de T1 Al2CuLi en forme de plaquettes sur les plans {111}Al, augmente la résistance de la direction préalablement tractionnée mais n'est pas responsable dans nos conditions expérimentales d'une forte aggravation de l'anisotropie. Dans le 7050, l'anisotropie diminue entre l’état mûri naturellement et l’état sur-revenu. La précipitation de sur-revenu du 7050 atténue l'effet de la texture cristallographique sur l'anisotropie et rend, en comparaison, le 2050 d’autant plus anisotrope. / This work aims to understand hot rolling texture evolution and anisotropy of mechanical behaviour on an Al-Cu-Li 2050 and an Al-Zn-Mg-Cu 7050, and aims to explain their differences. Crystallographic textures are analysed by EBSD and X-ray after hot plane strain compressions and after industrial hot rolling. Anisotropy of industrial hot rolled plates is investigated after different stretching and different ageing treatments by means of tensile tests at 0°, 45° and 90° to RD. Experimental results are compared to predictions using plasticity models (Taylor models). It is shown that, under the same processing conditions, the two alloys develop the same rolling textures up to strain of 2.6 ; it can be concluded that the presence of 1wt% of Li does not by itself favour a particular texture. However, it is shown that Brass component {110}<112> is favoured by an increasing rolling temperature, which is generally higher in the Al-Cu-Li than in the Al-Zn-Mg-Cu. Anisotropy of hot rolled 2050 is for a large part caused by crystallographic texture. It increases when stretch axis is at 0° and decreases when stretch axis is at 45°. Hardening precipitation, made by plate shape T1 Al2CuLi lying on the {111}Al, increases yield strength in the stretched direction but it is not responsible in our experimental conditions for a high increase of anisotropy. Anisotropy of 7050 is less important in the over aged state than in the natural aged state. Over ageing precipitation of 7050 reduces the effect of crystallographic texture on the anisotropy and makes 2050 appearing much more anisotropic.

O cinturão Fíngoè é uma unidade tectônica do Supercontinente Gondwana Oeste composta por rochas supracrustais formadas há aproximadamente 1.33 Ga. Essas rochas são portadoras de mineralizações de Au, Cu, Zn, Pb e Fe. Com cerca de 150 km de comprimento, e orientado WSW-ENE, este cinturão estende-se desde o Monte Atchiza a oeste até cerca de 30 km para leste da vila de Fíngoè no norte de Moçambique e consiste de uma extensa variedade de rochas metassedimentares e metavulcânicas. O cinturão Fíngoè apresenta especialização metalogenética para Au e Cu, que já foram explotados no passado em diversos locais. Muitos destes registros estão associados com magnetita e malaquita. Atualmente trabalhos de prospecção e pesquisa mineral têm sido realizados pela empresa de mineração African Queen Mines Ltda, através do projeto denominado de King Solomons, localizado na parte central do mesmo. A geologia da área abrangida pelo prospecto Mankombiti, mostra uma predominância de rochas carbonáticas, granitos e gabros. As rochas carbonáticas são consideradas importantes na gênese de depósitos tipo skarn e depósitos de substituição de metais de base e Au devido à sua natureza fortemente reativa. Os dados geocronológicos realizados neste trabalho indicaram uma idade precisa para a rocha intrusiva granítica associada à mineralização de 1079,1 ± 8,2 Ma, que poderia ser a idade da formação do skarn e consequentemente desta mineralização. Entretanto a idade obtida para o processo de alteração hidrotermal que afetou o gabro, na ordem de 657 ± 36 Ma e a idade modelo Pb-Pb sugerida pelo modelo de Stacey e Kramers (1975) para a calcopirita da mineralização principal de 725 Ma, sugerem que a mineralização, do prospecto Mankombiti é neoproterozóica. Para melhor entendimento dos processos que estiveram envolvidos na formação deste depósito skarn, duas hipóteses são consideradas: (i) poderia ser admitida a presença de corpos graníticos intrusivos em 700 Ma, situados em profundidade, que não foram ainda caracterizados, como responsáveis pela fonte de calor necessária, (ii) pode ser admitida ocorrência de um evento distensional em 700 Ma que produziria um adelgaçamento da litosfera e a consequente ascensão da astenosfera, produzindo uma elevação do fluxo térmico gerando os fluidos mineralizantes necessários. / The Fíngoè belt is a tectonic unit of West Gondwana Supercontinent, comprised of supracrustal rocks formed at approximately 1.33 Ga. These rocks are carriers of Au, Cu, Zn, Pb and Fe mineralization. With about 150 km long and oriented WSW- ENE, this belt extends from west of the Atchiza Mount to about 30 km east of the Fíngoè village in the north Mozambique, and consists of an extensive variety of metasedimentary and metavolcanic rocks. The Fíngoè metallogenic belt provides specialization for Au and Cu, which have been exploited in the past in various locations. Many of these records are associated with magnetite and malachite. Currently, the prospecting and mineral exploration have been conducted by the African Queen Mines Ltd mining company, through a project called the King Solomons, located in the central part of it. The geology of the studied area shows a predominance of carbonate rocks, granites and gabbros. The carbonate rocks are considered important in the genesis of the skarn deposits type and deposits of replacement for base metals and Au due to its highly reactive nature. The geochronological data performed in this work indicate a precise age of the 1079.1 ± 8.2 Ma for the intrusive granitic rock associated with mineralization, which could be interpreted as the age of the skarn and consequently of the mineralization. However the age obtained for the hydrothermal alteration that affected the gabbro at about 657 ± 36 Ma and the Pb-Pb model age suggested by the model of Stacey and Kramers (1975) for primary chalcopyrite mineralization at 725 Ma, suggesting that the mineralization of the Mankombiti prospectus was developed during the Neoproterozoic time. For understanding the processes that were involved in the skarn-type mineralization processes, two hypotheses are here considered: (i) could be admitted the presence of i ntrusive granitic rocks at 700 Ma, situated in depth, which have not yet been characterized, as responsible for the heat source required, (ii) may be admitted occurrence of an extensional event at 700 Ma to produce a thinning of the lithosphere and the uplift of the asthenosphere, producing high thermal flows generating the mineralization fluids.

La plupart des gisements de Ni-Cu sont issus de magmas komatiitique ou tholéiitique associés à des panaches mantelliques. Leur genèse fait intervenir l’exsolution d’un liquide sulfuré immiscible, l’interaction entre les liquides silicaté et sulfuré afin de concentrer ce-dernier en éléments chalcophiles, et l’accumulation du liquide sulfuré en quantités économiques. La saturation en sulfure est généralement atteinte en réduisant la solubilité des sulfures. Celle-ci se fait par assimilation de roches encaissantes siliceuses et/ou sulfurés.Le dyke d’Älgliden de la ceinture de Skellefte, en Suède, contient des sulfures de Cu et Ni dont les quantités ne sont actuellement pas économiques. La minéralisation d’Älgliden est atypique dans la mesure où elle contient d’importantes teneurs en Au, elle a un faible rapport Ni/Cu et enfin est formé dans un contexte de subduction. Le dyke recoupe un gisement porphyrique à Cu-Au contenant des sulfures ce qui laisse suggérer que la minéralisation d’Älgliden est formée par assimilation.Les objectifs de ce projet de recherche étaient d’examiner les processus de formation de la minéralisation d’Älgliden et son potentiel minier ainsi que de mieux comprendre la formation des gisements à Ni-Cu en contexte de subduction. Ce travail inclut l’étude pétrologique du minerai et de ses roches hôtes, la détermination de compositions minérales, l’analyse des éléments majeurs et traces sur roche totale et enfin des analyses des isotopes du soufre. Ce projet a été financé par la compagnie Boliden qui détient le gisement d’Älgliden.Le dyke est composé en majeure partie de norite à olivines, et minoritairement de leucogabbros. Les compositions sur roches totales, les textures magmatiques et les compositions minérales suggèrent que les norites à olivine se sont formées par accumulation d’olivine tandis que les leucogabbros représentent des liquides résiduels avec ou sans cristaux cumulus de plagioclase ± orthopyroxene. Les norites sont interprétées comme étant formées par une ou deux injections de bouillie cristalline suivie de cristallisation fractionnée. Le magma parent des roches d’Älgliden était un basalte hydraté et évolué dont la teneur en MgO est estimé à 6%.Le minerai sulfuré est principalement disséminé à travers l’ensemble de l’intrusion d’Älgliden. Quelques concentrations modérées de minerai se présentent sous la forme de sulfures en réseaux, de veines de sulfures et de sulfures massifs, lesquelles sont spatialement associées aux leucogabbros et aux xénolites de l’encaissant. L’association entre les leucogabbros et les concentrations en sulfures, leur faible teneur en métaux et leur faible rapport Ni/Cu suggèrent que la phase sulfuré s’est exsolvée tardivement au cours de la différentiation magmatique. Ce timing semble défavorable pour la minéralisation d’Älgliden puisqu’il inhibe à la fois l’interaction entre les liquides silicaté et sulfuré et l’accumulation du liquide sulfuré.La contamination du magma d’Älgliden par son encaissant n’est pas corroboré par les concentrations en élément trace et les compositions isotopiques du soufre. En revanche, ces données indiquent que le magma d’Älgliden s’est mis en place dans une zone de subduction où l’on pense que la saturation en sulfure a été atteinte par réduction d’un magma oxydé et riche en élément volatiles, via la cristallisation de magnétite et/ou dégazage. Les valeurs positives de δ34S suggèrent que l’apport de matériel dérivé du slab est responsable du caractère oxydé du magma d’Älgliden.L’état d’oxydation des magmas d’arc leur permet de dissoudre de grandes quantités de S et d’Au. Leur caractère évolué est responsable de leur fortes concentrations relatives en Au et leur faible rapport Ni/Cu. Ainsi, en contexte subduction les sulfures magmatiques sont susceptibles d’avoir ces caractéristiques, et si l’exsolution du liquide sulfuré a lieu plus tôt que dans le cas d’Älgliden cela pourrait conduire à la formation de gisements économiques. / Most major sulfide Ni-Cu deposits originated from komatiitic or tholeiitic magmas that formed in association with mantle plumes. Their genesis involves the segregation of a immiscible sulfide liquid, reaction of the sulfide liquid with silicate melt to upgrade the sulfide in chalcophile elements, and the concentration of the sulfide liquid in economic amounts. Saturation in sulfide is commonly achieved by lowering the sulfide solubility via assimilation of siliceous wall rock or by increasing the S content by adding S-bearing materials.The Älgliden dike in the Skellefte Belt in Sweden contains currently uneconomic Ni-Cu sulfide mineralization. The Älgliden mineralization is atypical insofar as it contains a significant amount of Au, has a low Ni/Cu ratio and formed in a subduction-related geodynamic setting. The host intrusion intrudes sulfide-bearing Cu-Au porphyry mineralization which led to the suggestion that the Älgliden Ni-Cu-Au mineralization was linked to the assimilation of sulfide-bearing wall rocks.The goals of this research project were to investigate the ore forming processes of the Älgliden mineralization and its ore potential, as well as to improve our understanding of the genesis of Ni-Cu deposits in subduction zones. The work is based on a petrological study of the ore and its host rocks, determination of mineral compositions, analyses of major and trace elements in bulk rocks, and sulfur isotope analyses. This was supported by the Boliden company which owns the deposit.The dike is composed mainly of olivine norites with minor leucogabbros. Bulk rock compositions, magmatic textures and mineral compositions suggest that the olivine norites formed by accumulation of olivine and that the leucogabbros represent residual melts with or without cumulus plagioclase ± orthopyroxene. The norites are interpreted to form by one or two injections of an olivine-rich crystal mush and subsequent fractional crystallization. The parental melt of the Älgliden rocks was a hydrous and evolved basalt estimated to contain ≈6 wt.% MgO.The sulfide ore is mainly disseminated throughout the whole Älgliden intrusion. Some weak ore concentrations occur as network to vein and massive sulfides that are spatially associated with the leucogabbros and wallrock xenoliths. The association between the leucogabbros and the concentrations of sulfide, their low ore grade and Ni/Cu ratio suggest that the sulfide segregated late in the differentiation process. This timing appears unfavorable for the Älgliden mineralization because it inhibited both sulfide-silicate liquid interaction and the accumulation of sulfide.Contamination of the Älgliden magma by its wall rocks is not supported by trace element data and S isotope compositions. Instead these data indicate that the Älgliden magma was emplaced above a subduction zone where the sulfide saturation is thought to occur by reduction of the oxidized and volatile-rich magma by magnetite fractionation and/or by degassing. Positive δ34S values suggest addition of slab-derived material which is thought to be responsible for the oxidized character of the Älgliden magma.The oxidation state of arc magmas allows them to carry large amounts of S and Au. Their evolved character is also responsible for their relatively high Au contents and low Ni/Cu. Such characteristics are likely to occur in magmatic sulfide mineralization in subduction zone settings, and if sulfide liquid segregation had occurred earlier than at Älgliden the process may have produced economic sulfide deposits.