A leptospirose é uma zoonose de importância mundial, e é causada por bactérias patogênicas do gênero Leptospira, pertencente à ordem Spirochaetales. Os seres humanos são hospedeiros acidentais e os surtos de leptospirose ocorrem em grandes centros urbanos após enchentes contaminadas por urina de ratos. Existem poucas informações a respeito de como Leptospira spp lida com situações de estresse induzidas pelo hospedeiro e pelo ambiente. O ferro é um íon essencial para a maioria dos seres vivos. A regulação de genes envolvidos por seu aporte e estoque na célula bacteriana é mediada por proteínas da família de reguladores transcricionais, Fur (ferric uptake regulator). L. interrogans sorovar Copenhageni possui quatro ortólogos para Fur, que foram alvo de estudo deste trabalho. A caracterização destes genes foi realizada através de estudos evolutivos, determinação do seu padrão de expressão em modelo animal e análise de modelagem estrutural. Durante o andamento do mestrado, ensaios paralelos revelaram resultados promissores na análise de expressão de genes relacionados ao sistema SOS, um mecanismo de resposta bacteriano a danos no material genético. Assim sendo, o estudo de caracterização de expressão em modelo animal suscetível e resistente à doença foi ampliado. Ensaios de qRT-PCR de cDNAs provenientes de pulmão, rim e fígado permitiram a identificação de dois genes que foram expressos quase que constitutivamente ao longo de toda a infecção em todos os órgãos e organismos estudados: fur979 e recA. Os demais foram requeridos em dias específicos da infecção. Quanto aos componentes do sistema SOS, observamos padrão de expressão específico para o rim, no quinto dia após a infecção. Para os estudos evolutivos de Fur foi gerada uma árvore filogenética que revelou o agrupamento de duas sequências da família Fur de Leptospira interrogans sorovar Copenhageni em ramos fechados com sequências muito similares a proteína Fur e Zur de Escherichia coli. Os outros dois ortólogos agruparam com as proteínas correspondentes nas demais espécies de Leptospira. Uma destas sequências apresentou padrão evolutivo específico dentre as espécies patogênicas. A modelagem da estrutura terciária, confirmou o padrão evolutivo obtido em nossa inferência filogenética. / Leptospirosis is a worldwide zoonosis caused by pathogenic bacteria from the genus Leptospira, order Spirochetales. Human beings are accidental hosts, and leptospirosis outbreaks occur in large urban centers after contact with contaminated waterby rodent urine. There are few informations concerning the mechanisms employed by Leptospira sppto deal with the stress induced by the host and the environment Iron is an essential ion to most of living beings. The regulation of genes involved in its uptake and maintenance in the bacterial cell is mediated by the transcriptional regulator family proteins, Fur (ferric uptake regulators). L. interrogans serovar Copenhageni possesses four orthologues for Fur, which were the focus of this work. The characterization of Leptospira Fur genes was done through evolutive studies, determination of their expression pattern on animal model and structural modeling analysis. In parallel, some experiments presented promising results for the expression analysis of genes related to the SOS system, a bacterial response mechanism to DNA damage. Therefore, the gene expression characterization on susceptible and resistant animal model was amplified. qRT-PCR experiments of cDNA from lung, kidney and liver allowed the identification of two genes expressed almost constitutively during the infection in all organs and organisms : fur979 and recA. The others were required in specific days of the infection. Curiously, the SOS system components showed specific expression pattern in the fifth day after inoculation, in kidney. For the Fur evolutive studies, a phylogenetic tree was inferred, revealing the clustering of two Fur family sequences from Leptospira interrogans serovar Copenhageni in closed branches with very similar sequences to Fur and Zur proteins from Escherichia coli. The other two orthologues clustered with corresponding proteins in the other Leptospira species. One of these sequences presented a specific evolutive pattern among pathogenic species. The tertiary structure modeling confirmed the evolutive pattern obtained in our phylogenetic inference.

A leptospirose é uma zoonose de importância mundial, e é causada por bactérias patogênicas do gênero Leptospira, pertencente à ordem Spirochaetales. Os seres humanos são hospedeiros acidentais e os surtos de leptospirose ocorrem em grandes centros urbanos após enchentes contaminadas por urina de ratos. Existem poucas informações a respeito de como Leptospira spp lida com situações de estresse induzidas pelo hospedeiro e pelo ambiente. O ferro é um íon essencial para a maioria dos seres vivos. A regulação de genes envolvidos por seu aporte e estoque na célula bacteriana é mediada por proteínas da família de reguladores transcricionais, Fur (ferric uptake regulator). L. interrogans sorovar Copenhageni possui quatro ortólogos para Fur, que foram alvo de estudo deste trabalho. A caracterização destes genes foi realizada através de estudos evolutivos, determinação do seu padrão de expressão em modelo animal e análise de modelagem estrutural. Durante o andamento do mestrado, ensaios paralelos revelaram resultados promissores na análise de expressão de genes relacionados ao sistema SOS, um mecanismo de resposta bacteriano a danos no material genético. Assim sendo, o estudo de caracterização de expressão em modelo animal suscetível e resistente à doença foi ampliado. Ensaios de qRT-PCR de cDNAs provenientes de pulmão, rim e fígado permitiram a identificação de dois genes que foram expressos quase que constitutivamente ao longo de toda a infecção em todos os órgãos e organismos estudados: fur979 e recA. Os demais foram requeridos em dias específicos da infecção. Quanto aos componentes do sistema SOS, observamos padrão de expressão específico para o rim, no quinto dia após a infecção. Para os estudos evolutivos de Fur foi gerada uma árvore filogenética que revelou o agrupamento de duas sequências da família Fur de Leptospira interrogans sorovar Copenhageni em ramos fechados com sequências muito similares a proteína Fur e Zur de Escherichia coli. Os outros dois ortólogos agruparam com as proteínas correspondentes nas demais espécies de Leptospira. Uma destas sequências apresentou padrão evolutivo específico dentre as espécies patogênicas. A modelagem da estrutura terciária, confirmou o padrão evolutivo obtido em nossa inferência filogenética. / Leptospirosis is a worldwide zoonosis caused by pathogenic bacteria from the genus Leptospira, order Spirochetales. Human beings are accidental hosts, and leptospirosis outbreaks occur in large urban centers after contact with contaminated waterby rodent urine. There are few informations concerning the mechanisms employed by Leptospira sppto deal with the stress induced by the host and the environment Iron is an essential ion to most of living beings. The regulation of genes involved in its uptake and maintenance in the bacterial cell is mediated by the transcriptional regulator family proteins, Fur (ferric uptake regulators). L. interrogans serovar Copenhageni possesses four orthologues for Fur, which were the focus of this work. The characterization of Leptospira Fur genes was done through evolutive studies, determination of their expression pattern on animal model and structural modeling analysis. In parallel, some experiments presented promising results for the expression analysis of genes related to the SOS system, a bacterial response mechanism to DNA damage. Therefore, the gene expression characterization on susceptible and resistant animal model was amplified. qRT-PCR experiments of cDNA from lung, kidney and liver allowed the identification of two genes expressed almost constitutively during the infection in all organs and organisms : fur979 and recA. The others were required in specific days of the infection. Curiously, the SOS system components showed specific expression pattern in the fifth day after inoculation, in kidney. For the Fur evolutive studies, a phylogenetic tree was inferred, revealing the clustering of two Fur family sequences from Leptospira interrogans serovar Copenhageni in closed branches with very similar sequences to Fur and Zur proteins from Escherichia coli. The other two orthologues clustered with corresponding proteins in the other Leptospira species. One of these sequences presented a specific evolutive pattern among pathogenic species. The tertiary structure modeling confirmed the evolutive pattern obtained in our phylogenetic inference.

[pt] Sabe-se que o coagulante sulfato férrico pode ser obtido através da reação de oxidação entre sulfato ferroso e peróxido de hidrogênio em meio ácido. Porém, o método conhecido de obtenção deste coagulante em escala industrial utilizando o peróxido de hidrogênio como agente oxidante não proporciona condições economicamente atrativas, frente aos demais processos. Este potente agente oxidante sofre forte influência da temperatura e da presença de íons ferro no seu processo de auto decomposição em água e oxigênio. Pode-se considerar que as condições do meio reacional, na etapa de adição do agente oxidante, são os fatores determinantes para a produção do coagulante férrico com o maior aproveitamento do peróxido de hidrogênio adicionado. O presente trabalho teve como objetivo investigar as condições necessárias para a produção do coagulante férrico utilizando o peróxido de hidrogênio, em um processo economicamente competitivo. A pesquisa foi fundamentada nas técnicas de planejamento de experimentos e otimização de processos. A modelagem matemática do processo possibilitou a definição da magnitude dos parâmetros a serem utilizados otimizando o processo e a especificação das características desejadas do produto final. As variáveis independentes estudadas na modelagem matemática foram: temperatura (7,5 – 27,5 graus celsius), quantidade de peróxido de hidrogênio (100 – 300 porcento) referente à sua quantidade estequiométrica e a diluição do meio utilizando água (100 – 300 porcento) referente à sua quantidade estequiométrica. As quantidades estequiométricas dos reagentes foram determinadas visando ao atingimento das especificações de um coagulante férrico comercial. O modelo desenvolvido foi sobre a Conversão de Fe2(+) em Fe3(+) (porcento) e avaliado através da Análise da Variância (ANOVA). As condições ótimas escolhidas para o ponto ótimo foram: temperatura igual a 17,5 graus celsius, 150 porcento da quantidade estequiométrica de peróxido de hidrogênio e 200 porcento da quantidade estequiométrica de água. A resposta da etapa de otimização indicou uma conversão de 96,17 porcento de Fe2(+) em Fe3(+), resultando em um coagulante dentro dos padrões especificados por norma técnica. O modelo matemático obtido previu uma conversão de 96,13 porcento de Fe2(+) em Fe3(+), resultando em um erro percentual de 0,043 porcento entre o resultado predito pelo modelo matemático e o resultado experimental. As análises das superfícies de resposta e da quantidade de peróxido de hidrogênio residual em solução indicaram que o controle do processo em baixas temperaturas contribui para o melhor aproveitamento do peróxido de hidrogênio na conversão de Fe2(+) em Fe3(+), devido à desaceleração da auto decomposição incitada pelo fator temperatura. A análise do potencial de redução ao longo da reação em função do perfil de conversão mostrou que conversões acima de 90 porcento de Fe2(+) em Fe3(+) apresentaram potencial redox (Eh) correspondente acima de 0,70 Volts, indicando a possibilidade da utilização deste parâmetro no controle da conversão em processos industriais. / [en] It is known that the coagulant ferric sulfate can be obtained by the oxidation reaction of ferrous sulfate with hydrogen peroxide in acidic medium. However, the known method of obtaining this coagulant on an industrial scale using hydrogen peroxide as an oxidizing agent do not provide economically attractive conditions compared to other processes. This potent oxidizing agent undergoes strong influence of the temperature and the presence of iron ions in its process of self-decomposition in water and oxygen. It can be considered that the conditions of the reaction medium in the step of adding the oxidizing agent are the determining factors for the production of the ferric coagulant with the greatest use of the added hydrogen peroxide. The present work had the objective of investigating the necessary conditions for the production of the ferric coagulant using the hydrogen peroxide as an economically competitive process. The research was based on the techniques of factorial design and process optimization. The mathematical modeling of the process allowed the definition of the magnitude of the parameters to be used, optimizing the process and specifying the desired characteristics of the final product. The independent variables studied in the mathematical modeling were: temperature (7,5 – 27,5 celsius degrees), amount of hydrogen peroxide (100-300 percent) relative to its stoichiometric amount, and dilution of the medium using water (100-300 percent) relative to its stoichiometric amount. The stoichiometric quantities of the reactants were determined in order to reach the specifications of a commercial ferric coagulant. The model developed was on Conversion of Fe2(+) to Fe3(+) (percent) and evaluated through Analysis of Variance (ANOVA). The optimum conditions chosen for the optimum were: temperature equal to 17,5 Celsius degrees, 150 percent of the stoichiometric amount of hydrogen peroxide and 200 percent of the stoichiometric amount of water. The optimization of the response surfaces indicated a conversion of 96.17 percent Fe2(+) to Fe3(+), resulting in a coagulant within the characteristics specified by the technical standard. The obtained mathematical model predicted a conversion of 96.13 percent Fe2(+) to Fe3(+), resulting in a percentage error of 0,043 percent between the predicted results by the mathematical model and the experimental results. The analysis of the response surfaces and the amount of residual hydrogen peroxide in solution indicated that the control of the process at low temperatures contributes to the better utilization of the hydrogen peroxide in the conversion of Fe2(+) into Fe3(+), due to the deceleration of the self-induced decomposition by the factor temperature. The analysis of the reduction potential along the conversion profile function showed that conversions above 90 percent of Fe2(+)into Fe3(+) presented a corresponding redox potential (Eh) above 0,70 Volts, indicating the possibility of using this parameter for the control of conversion into industrial processes.

Ferric ABC Transporters. Pathogenic bacteria have evolved specialised iron acquisition systems that allow them to effectively colonise a host. One of these systems is the ferric binding protein (Fbp) complex that is a member of the ATP-Binding Cassette (ABC) superfamily of small molecule transporters. The Fbp complex is made up of three-components (FbpABC) that transports ferric iron from the periplasm to the cytoplasm of many Gram negative bacteria. FbpA binds iron in the periplasm and transports it to the FbpB transporter complex that permeates the cytoplasmic membrane. Here the iron is actively transported by FbpB through the membrane that is powered by ATP hydrolysis catalysed by FbpC, the cytoplasmic ATPase. Burkholderia cenocepacia is an opportunist pathogen that colonises the lungs of cystic fibrosis patients and is particularly resistant to antibiotic treatment. In this study the iron uptake system of B. cenocepacia strain J2315 is investigated. A putative FbpA from B. cenocepacia J2315 was expressed in the periplasm of Escherichia coli cells and the recombinant FbpA B. cenocepacia protein purified. The structural and electrochemical properties of native FbpA B. cenocepacia were investigated using UV Visible spectroscopy, spectro-electrochemistry, mass spectrometry and crystallographic techniques. It appears that FbpA B. cenocepacia is a novel member of the FbpA superfamily that selectively utilises citrate as an exogenous anion in ferric iron co-ordination. This is the first instance that a recombinant ferric binding protein has been documented as preferentially utilising citrate in this manner. The putative ATPase from B. cenocepacia (FbpC B. cenocepacia) was also expressed in E. coli but it was found to be insoluble. A number of expression systems were tested but none were found to be successful in generating sufficient quantities of FbpC B. cenocepacia for structural studies. Human β-defensin 2. Despite daily contact with a range of microorganisms, mammals do not regularly succumb to pathogenic invasion. One reason is the presence of an important defence mechanism uses a reservoir of antimicrobial peptides (AMPs) that are expressed in eukaryotes as a means of innate immunity. The AMP superfamily is composed of over 900 members, displays broad structural and sequence diversity and is active against a wide range of bacteria, fungi and viruses. β-defensins are small (3-5 kDa), cationic peptides that display antimicrobial activity against a range of microbes and have also been shown to act as chemo-attractants (chemokines) within the adaptive immune system. In this study we obtained milligram amounts of pure human β-defensin 2 (HBD2) for functional studies by the development of a method for the rapid expression and purification of the recombinant peptide. A clone encoding a thioredoxin-HBD2 fusion protein was designed for the expression of soluble peptide in E. coli cells that was purified by simple affinity chromatography. The HBD2 peptide was cleaved from the fusion by an efficient protease step and further purified to yield pure HBD2. This recombinant HBD2 defensin was shown to be active against a Mycobacterium tuberculosis mutant strain.

The need of making arsenic contaminated ground water potable is urgent in parts of Burkina Faso. An implementation of a treatment design using Granular Ferric Hydroxide (GFH) is under development. Water from a tube-well in Lilgomdé, Yatenga province, Burkina Faso, has been treated with the adsorbent GFH through column experiments. The water had an arsenic concentration varying between 99 and 215 μg/L and an average pH of 7.9. The study has shown that arsenic, predominantly in the form of arsenate, can be adsorbed to the material in significant amounts despite a high natural pH and the presence of ions competing with arsenic for adsorption sites on the GFH. When run through the column, the pH of the effluent water drastically decreased in the beginning. However, the low pH was soon followed by a slower readjustment towards the pH of the influent water. The adsorption of phosphates and fluorides was also studied. Both competitors exist in higher molar quantities than arsenic in the ground water. Even though arsenic displays a higher affinity for the GFH, an average 44 % of total phosphate and 64 % of the fluoride were adsorbed, making them a factor affecting the results of the study. Hydrogen carbonate is also believed to affect the adsorption process but this could not be confirmed. The empty bed contact time (EBCT), describing the average time of contact between the adsorbent and the water, has shown to be of importance. Increasing the EBCT resulted in notably more arsenic being adsorbed per volume GFH. When increasing the contact time, the study showed that reducing the speed of the flow was more effective than increasing the volume of the adsorbent. The GFH was also found to have a self-regenerating ability to a certain extent. When interrupting the experiment and leaving the column material in the aqueous solution for several days, the arsenic adsorption capacity after the break was shown to be higher than just before it. A 13 % increased capacity was shown in one experiment. Conclusively, the results of this study suggest no hindrances towards developing larger scale columns and prototypes to be applied at tube-well pump stations. Further investigations on the treatment method with GFH, on arsenic contaminated water, are recommended.

The World Health Organization (WHO) states that 30,000 children under the age of five die each day worldwide. Around a quarter of these die from diarrheal disease caused by microbial infection. In addition to this high mortality rate, there are data emerging on the morbidity effects of diarrheal disease, for example a few episodes of diarrhea in the first two years of life can remove 10 IQ points and lead to growth deficiency. Vibrio cholerae, the causative agent of the diarrheal disease cholera, is a serious problem in third world countries, where sanitary and hygiene infrastructure is very poor, and claims several thousand lives every year. In order to better understand the pathogenicity regulation in V. cholerae, structural and functional investigations of a hypothetical protein family present in pathogenicity islands and a transcriptional regulator protein for DNA-binding were investigated. Two adjacent genes, vc1804 and vc1805, encode hypothetical proteins within the Vibrio pathogenicity island-2 (VPI-2) of Vibrio cholerae, and are part of a cluster of genes only present in pathogenic strains of the bacterium. Paralogous adjacent genes, vc0508 and vc0509, are also present within a second pathogenicity island, the Vibrio seventh pandemic island-2 (VSP-2), of V. cholerae O1 El Tor and O139 serogroup isolates. Sequence similarity suggests that the VC0508, VC0509, VC1804 and VC1805 proteins will share a similar fold. The crystal structures of VC0508, VC0509 and VC1805 have been determined to a resolution of 1.9, 2.4 and 2.1 Å, respectively. Several recombinant constructs of vc1804 were made, but no soluble proteins were expressed. This hypothetical protein family reveals structural homology to human mitochondrial protein p32. Human p32 is a promiscuous protein known to bind to a variety of partners including the globular head component of C1q. We have shown that VC1805 binds to C1q. One possibility is that VC1805 is involved in adherence of the bacterium to membrane-bound C1q in the gut. To explore the roles of VC0508, VC0509, VC1804 and VC1805 in vivo, gene knockout and animal model studies of those proteins are underway. The ferric uptake regulator (Fur), a metal-dependent DNA-binding protein, acts as both a repressor and activator of numerous genes involved in maintaining iron homeostasis in bacteria. It has also been demonstrated in Vibrio cholerae that Fur plays an additional role in pathogenesis, and this opens up the potential of Fur as a drug target for cholera. The first crystal structure of a Fur protein, from Pseudomonas aeruginosa, revealed a dimeric molecule with each monomer containing a dimerization domain, a helical DNA-binding domain and two metal binding sites: Zn1 is proposed to be a regulatory Fe-binding site, and Zn2 is proposed to be a structural Zn-binding site. Here we present the crystal structure of V. cholerae Fur (VcFur) that reveals a very different orientation of the DNA-binding domains. Accompanying these structural changes are alterations in the amino acids coordinating the zinc at the Zn2 site, and this lends support to this being the site regulated by iron. There is no evidence of metal binding to the cysteines that are conserved in many Fur homologues, including the much-studied E. coli Fur. An analysis of the metal binding properties shows that like other Fur proteins, VcFur can be activated by a range of divalent metals. EPR spectroscopy measurements of the movements of the DNA-binding domain, in the presence of DNA and different metals, are underway.

Phosphonate antiscalants are commonly used in nanofiltration and reverse osmosis water treatment to prevent membrane fouling by mineral scale. In many circumstances it is desirable to remove these phosphonate compounds before concentrate disposal or further treatment. This research investigated the removal of phosphonate compounds from simulated membrane concentrate solutions using ferric hydroxide adsorbents. Two phosphonate antiscalants were investigated, Permatreat 191® (PT191) and nitrilotrimethylphosphonic acid (NTMP). Batch adsorption isotherms and column breakthrough and regeneration experiments were performed on two commercial adsorbents and a ferric hydroxide loaded polyacrylonitrile fiber adsorbent prepared in our laboratory. The best performing adsorbent was Granular Ferric Hydroxide® (GFH) obtained from GEH Wasserchemie. Adsorption isotherms measured after 24-hour equilibration periods showed initial concentration effects, whereby the isotherms were dependent on the initial adsorbate concentration in solution. Significant differences in adsorption behavior were observed between the PT191 and the NTMP adsorbates. Differences in adsorption behavior between NTMP and PT191 are all consistent with the PT191 containing fewer phosphonate functional groups per molecule than NTMP. Desorption rates were bimodal, with 40-50% of the adsorbed phosphonate being released on a time scale of 10-24 hours, while the remaining fraction was released approximately one order of magnitude more slowly. The slow desorbing fraction primarily resulted from equilibrium effects resulting from significant phosphonate adsorption, even in 1.0 mol/L NaOH solutions. Complete regeneration could not be achieved, even after eluting the adsorbent columns with more than 300 bed volumes of 1.0 mol/L NaOH. However, the incomplete regeneration had only a minor effect on phosphonate uptake in subsequent column breakthrough experiments.

Níquel laterítico compõe 70% das reservas disponíveis do metal. A produção de níquel a partir dessas reservas representa 40%, dos quais é possível extrair também cobre e cobalto. Isso ocorre devido ao alto teor de impurezas, principalmente ferro. Com a crescente demanda desses metais, o uso das reservas de lateritas de níquel passou a ser mais profundamente investigado, assim como o desenvolvimento de processos hidrometalúrgicos. Nesse caso, o íon férrico prejudica a recuperação do níquel e do cobalto, uma vez que em trocas iônicas esse metal compete na ocupação dos sítios catiônicos. Em processos de extração por solvente um efeito semelhante é observado. Além disso, durante a eventual precipitação do ferro ocorre a coprecipitação. Assim, para a troca iônica, o íon ferroso pode ser menos prejudicial do que o férrico. O presente trabalho teve por objetivo o estudo do processo de redução do íon férrico em solução aquosa, e também a posterior obtenção de cobalto e níquel por meio de resinas quelantes. Estudou-se o processo de redução do íon férrico e o efeito na adsorção de metais por troca iônica. Os ensaios de redução química do íon férrico em solução foram estudados utilizando ditionito de sódio, metabissulfito de sódio e sulfito de sódio. Os ensaios com os agentes redutores ditionito e metabissulfito de sódio foram feitos em São Paulo, e os ensaios com o sulfito de sódio foram feitos na The University of British Columbia. Os agentes redutores foram adicionados na solução monoelementar de ferro para redução do potencial redox. As variáveis potencial redox, entre 860mV e 240mV; pH, entre 0,5 e 3,5; temperatura, entre 25°C e 60°C; e tempo, entre 30min e 96 horas, foram estudadas em frascos erlenmeyer sob agitação constante. Analisou-se, então, a redução do íon férrico em solução multielementar de níquel laterítico. Nos ensaios de troca iônica, realizados em batelada e em coluna, utilizou-se a resina quelante Lewatit TP 207, de grupo funcional iminodiacetato, e a resina Lewatit TP220, de grupo funcional bis-picolilamina. Três soluções foram estudadas: uma preparada com Fe(III), outra com Fe(II) e a terceira com Fe(III) após o processo de pré-redução. Os ensaios em batelada foram realizados com a utilização de frascos erlenmeyer, sob agitação constante, com 100mL de solução para 1mL de resina. Estudou-se o efeito do pH, entre 0,5 e 3,5; tempo, entre 30min e 480min; e temperatura, entre 25°C e 60°C. Nos ensaios em sistema contínuo, as três soluções foram alimentadas em colunas de vidro preenchidas com resina. A solução foi alimentada com bombas peristálticas a vazão constante. Para eluição das colunas, ácido sulfúrico 1mol.L-1 foi alimentado na coluna com utilização de bomba peristáltica. A segunda parte do trabalho, realizado na The University of British Columbia, foi o estudo do uso de sulfito de sódio no processo de pré-redução. Foram estudadas duas resinas: a Lewatit TP 207, seletiva para cobre; e a Lewatit TP 220, seletiva para níquel e cobalto. O sulfito de sódio foi adicionado na solução para redução do potencial, em frascos, e colocado sob agitação constante. Após reação, as soluções foram colocadas em contato com a resina quelante, e ficaram em agitação. Os ensaios em batelada foram realizados e o efeito do pH estudado entre 0,5 e 3,5. No processo em coluna, a Coluna 1, preenchida com a resina Lewatit TP 207, foi utilizada para remoção do cobre; e a solução de saída foi alimentada na Coluna 2, preenchida com a resina Lewatit TP 220. Para a eluição, foram estudados os ácidos clorídricos e sulfúricos em duas diferentes concentrações, 1mol.L-1 e 2mol.L-1. Hidróxido de sódio foi utilizado para remover o ferro na solução obtida na saída da Coluna 2. A separação do cobalto da solução foi feita utilizando a técnica de extração por solventes (Cyanex 272 20%), estudando o efeito do pH, 4,0 e 5,0, e da temperatura, 25°C e 65°C. Os resultados mostraram que a redução do íon férrico utilizando ditionito de sódio foi de 100% na solução monoelementar e de 70% na multielementar contendo os outros metais. Nos ensaios de troca iônica em batelada, utilizando a resina TP 207, 62% do cobre foi adsorvido na solução após processo de pré-redução. Para solução com Fe(II), a adsorção de cobre foi de 61%; e para solução com Fe(III), 49%. Nos ensaios de troca iônica após pré-redução do ferro com sulfito de sódio, a adsorção do cobre foi de 69% em pH 2,0 pela resina TP 207. A resina TP 220 foi mais seletiva para níquel e cobalto em pH 2,0, em que as adsorções destes metais foram 32,5% e 69%, respectivamente. Nos ensaios em coluna, a Coluna 1 foi utilizada para remoção de cobre, porém houve perda de 17% de níquel e 7% de cobalto. Na alimentação da Coluna 2, verificou-se que 98% do níquel e 84% do cobalto foram adsorvidos. A solução obtida da Coluna 2 teve concentração de 618mg.L-1 de ferro, 13231mg.L-1 de níquel e 179mg.L-1 de cobalto. A remoção de 100% do ferro foi possível em pH 4,0. Para separação do cobalto da solução rica em níquel, utilizou-se a extração por solventes com o Cyanex 272 20% em querosene, no qual 99% do cobalto foi separado da solução a 65°C e pH 5,0, sem perda de níquel. Para estudos futuros, a remoção do cobre no início do processo pode ser explorada com a utilização de outras técnicas, a fim de se evitarem perdas de níquel e cobalto. Outro ponto que pode vir a ser explorado é a máxima utilização das colunas de troca iônica nas mesmas condições deste trabalho - solução com Fe(III), com Fe(II) e após processo de pré-redução - sobretudo em escala piloto, para estudar o efeito do estado de oxidação do ferro em um possível envenenamento da resina. / Nickel laterite ores represent 70% of the available metal reserves. The nickel production from these reserves represents 40%, where it is also possible extract copper and cobalt. It occurs due to the high impurities content, mainly iron. With the growing demand of these metals, the use of nickel laterite reserves became more deeply investigated, as well as hydrometallurgical process development. In this case, the ferric iron difficult the nickel and cobalt recovery, once in ion exchange processes this metal competes in the occupation of the cationic sites. In solvent extraction processes the same effect is observed. Besides that, during the eventual iron precipitation there is a co-precipitation. Therefore, for ion exchange, ferrous iron may be less damaging than ferric iron. The aim of this work was to study the reducing process of ferric iron in aqueous solution, and also the subsequent obtaining of cobalt and nickel through chelating resins. It was studied the reducing process of ferric iron and the effect of it in metals adsorption by ion exchange. Experiments of chemical reduction of ferric iron in solution were studied using sodium dithionite, sodium metabisulfite and sodium sulfite. Experiments with reducing agents sodium dithionite and metabisulfite were performed in São Paulo, and experiments with sodium sulfite were performed in The University of British Columbia. Reducing agents were added in ferric iron mono-elementary solution to decrease the redox potential. The variables potential redox, between 860mV and 240mV; pH, between 0,5 and 3,5; temperature, between 25°C e 60°C; and time, between 30min and 96 hours were studied in erlenmeyer flasks under constant stirring. Then, analyzed ferric iron reduction in multielementary solution of nickel laterite. In ion exchange experiments, performed in batch and column, it was used chelating resin Lewatit TP 207, with iminodiacetate functional group, and resin Lewatit TP 220, with bis-picolylamine functional group. Three solutions were studied: prepared with Fe(III), other with Fe(III) and the third with Fe(III) after pre-reducing process. Experiments in batch system were performed using erlenmeyer flasks, under constant stirring, with 100mL of solution to 1mL of resin. It was studied the effect of pH, between 0,5 and 3,5, time, between 30min and 480min, and temperature, between 25°C e 60°C. In experiments in continuous system, the three solutions were fed in glass columns filled with resin. The solution was fed using peristaltic pumps at constant flow rate. For column elution, sulfuric acid 1mol.L-1 was fed to the column using peristaltic pumps. The second part of this work, performed at The University of British Columbia, was the study of sodium sulfite application at prereducing process. It was studied two resins: Lewatit TP 207, selective for copper, and Lewatit TP 220, selective for nickel and cobalt. Sodium sulfite was added to the solution to decrease the potential, in flasks and it was placed under constant stirring. After reaction, the solution was placed in contact to the chelating resin, which was placed under stirring. Batch experiments were performed, and the effect of pH was studied between 0,5 and 3,5. In column process, the Column 1, filled with Lewatit TP 207, was used for copper removal, and output solution was feed in Column 2, filled with Lewatit TP 220. For the elution, it was studied sulfuric and hydrochloric acids in two different concentrations, 1mol.L-1 e 2mol.L-1. Sodium hydroxide was used for iron removal from solution obtained in Column 2 output. Cobalt separation was performed using solvent extraction technique (Cyanex 272 20%), studying the effect of pH, 4,0 and 5,0, and temperature, 25°C e 65°C. Results shows that ferric iron reduction using sodium dithionite was 100% in mono-elementary solution and 70% in multi-elementary solution with other metals. In ion exchange experiments performed in batch using resin TP 207, 62% of copper was adsorbed by the resin after pre-reducing process. For solution with Fe(II), the copper adsorption was 61%, and for solution with Fe(III), 49%. In ion exchange experiments after pre-reducing process using sodium sulfite, the copper adsorption was 69% at pH 2,0 by the resin TP 207. The resin TP 220 was more selective for nickel and cobalt at pH 2,0, where these metals adsorptions were 32,5% and 69%, respectively. In experiments performed in column, the Column 1 was used for copper removal, however there were losses of nickel (17%) and cobalt (7%). In the feeding of Column 2, it was found that 98% of nickel and 84% of cobalt were adsorbed. Solution obtained in Column 2 had concentration of iron 618mg.L-1, nickel was 13231mg.L-1 and cobalt 179mg.L-1. The iron removal was 100% at pH 4,0. For cobalt separation in nickel-rich solution, it was used the solvent extraction with Cyanex 272 20% with kerosene, where 99% of cobalt was separated from solution at 65°C and pH 5,0, without nickel loss. For future studies, the copper removal in the beginning of the process can be explored using other techniques, in order to avoid nickel and cobalt losses. Another point that can be explored is the maximum use of ion exchange columns in the same conditions of this work - solution with Fe(III), with Fe(II) and after the pre-reducing process - mostly on a pilot scale, to study the effect of iron oxidation state on possible resin poisoning.

Níquel laterítico compõe 70% das reservas disponíveis do metal. A produção de níquel a partir dessas reservas representa 40%, dos quais é possível extrair também cobre e cobalto. Isso ocorre devido ao alto teor de impurezas, principalmente ferro. Com a crescente demanda desses metais, o uso das reservas de lateritas de níquel passou a ser mais profundamente investigado, assim como o desenvolvimento de processos hidrometalúrgicos. Nesse caso, o íon férrico prejudica a recuperação do níquel e do cobalto, uma vez que em trocas iônicas esse metal compete na ocupação dos sítios catiônicos. Em processos de extração por solvente um efeito semelhante é observado. Além disso, durante a eventual precipitação do ferro ocorre a coprecipitação. Assim, para a troca iônica, o íon ferroso pode ser menos prejudicial do que o férrico. O presente trabalho teve por objetivo o estudo do processo de redução do íon férrico em solução aquosa, e também a posterior obtenção de cobalto e níquel por meio de resinas quelantes. Estudou-se o processo de redução do íon férrico e o efeito na adsorção de metais por troca iônica. Os ensaios de redução química do íon férrico em solução foram estudados utilizando ditionito de sódio, metabissulfito de sódio e sulfito de sódio. Os ensaios com os agentes redutores ditionito e metabissulfito de sódio foram feitos em São Paulo, e os ensaios com o sulfito de sódio foram feitos na The University of British Columbia. Os agentes redutores foram adicionados na solução monoelementar de ferro para redução do potencial redox. As variáveis potencial redox, entre 860mV e 240mV; pH, entre 0,5 e 3,5; temperatura, entre 25°C e 60°C; e tempo, entre 30min e 96 horas, foram estudadas em frascos erlenmeyer sob agitação constante. Analisou-se, então, a redução do íon férrico em solução multielementar de níquel laterítico. Nos ensaios de troca iônica, realizados em batelada e em coluna, utilizou-se a resina quelante Lewatit TP 207, de grupo funcional iminodiacetato, e a resina Lewatit TP220, de grupo funcional bis-picolilamina. Três soluções foram estudadas: uma preparada com Fe(III), outra com Fe(II) e a terceira com Fe(III) após o processo de pré-redução. Os ensaios em batelada foram realizados com a utilização de frascos erlenmeyer, sob agitação constante, com 100mL de solução para 1mL de resina. Estudou-se o efeito do pH, entre 0,5 e 3,5; tempo, entre 30min e 480min; e temperatura, entre 25°C e 60°C. Nos ensaios em sistema contínuo, as três soluções foram alimentadas em colunas de vidro preenchidas com resina. A solução foi alimentada com bombas peristálticas a vazão constante. Para eluição das colunas, ácido sulfúrico 1mol.L-1 foi alimentado na coluna com utilização de bomba peristáltica. A segunda parte do trabalho, realizado na The University of British Columbia, foi o estudo do uso de sulfito de sódio no processo de pré-redução. Foram estudadas duas resinas: a Lewatit TP 207, seletiva para cobre; e a Lewatit TP 220, seletiva para níquel e cobalto. O sulfito de sódio foi adicionado na solução para redução do potencial, em frascos, e colocado sob agitação constante. Após reação, as soluções foram colocadas em contato com a resina quelante, e ficaram em agitação. Os ensaios em batelada foram realizados e o efeito do pH estudado entre 0,5 e 3,5. No processo em coluna, a Coluna 1, preenchida com a resina Lewatit TP 207, foi utilizada para remoção do cobre; e a solução de saída foi alimentada na Coluna 2, preenchida com a resina Lewatit TP 220. Para a eluição, foram estudados os ácidos clorídricos e sulfúricos em duas diferentes concentrações, 1mol.L-1 e 2mol.L-1. Hidróxido de sódio foi utilizado para remover o ferro na solução obtida na saída da Coluna 2. A separação do cobalto da solução foi feita utilizando a técnica de extração por solventes (Cyanex 272 20%), estudando o efeito do pH, 4,0 e 5,0, e da temperatura, 25°C e 65°C. Os resultados mostraram que a redução do íon férrico utilizando ditionito de sódio foi de 100% na solução monoelementar e de 70% na multielementar contendo os outros metais. Nos ensaios de troca iônica em batelada, utilizando a resina TP 207, 62% do cobre foi adsorvido na solução após processo de pré-redução. Para solução com Fe(II), a adsorção de cobre foi de 61%; e para solução com Fe(III), 49%. Nos ensaios de troca iônica após pré-redução do ferro com sulfito de sódio, a adsorção do cobre foi de 69% em pH 2,0 pela resina TP 207. A resina TP 220 foi mais seletiva para níquel e cobalto em pH 2,0, em que as adsorções destes metais foram 32,5% e 69%, respectivamente. Nos ensaios em coluna, a Coluna 1 foi utilizada para remoção de cobre, porém houve perda de 17% de níquel e 7% de cobalto. Na alimentação da Coluna 2, verificou-se que 98% do níquel e 84% do cobalto foram adsorvidos. A solução obtida da Coluna 2 teve concentração de 618mg.L-1 de ferro, 13231mg.L-1 de níquel e 179mg.L-1 de cobalto. A remoção de 100% do ferro foi possível em pH 4,0. Para separação do cobalto da solução rica em níquel, utilizou-se a extração por solventes com o Cyanex 272 20% em querosene, no qual 99% do cobalto foi separado da solução a 65°C e pH 5,0, sem perda de níquel. Para estudos futuros, a remoção do cobre no início do processo pode ser explorada com a utilização de outras técnicas, a fim de se evitarem perdas de níquel e cobalto. Outro ponto que pode vir a ser explorado é a máxima utilização das colunas de troca iônica nas mesmas condições deste trabalho - solução com Fe(III), com Fe(II) e após processo de pré-redução - sobretudo em escala piloto, para estudar o efeito do estado de oxidação do ferro em um possível envenenamento da resina. / Nickel laterite ores represent 70% of the available metal reserves. The nickel production from these reserves represents 40%, where it is also possible extract copper and cobalt. It occurs due to the high impurities content, mainly iron. With the growing demand of these metals, the use of nickel laterite reserves became more deeply investigated, as well as hydrometallurgical process development. In this case, the ferric iron difficult the nickel and cobalt recovery, once in ion exchange processes this metal competes in the occupation of the cationic sites. In solvent extraction processes the same effect is observed. Besides that, during the eventual iron precipitation there is a co-precipitation. Therefore, for ion exchange, ferrous iron may be less damaging than ferric iron. The aim of this work was to study the reducing process of ferric iron in aqueous solution, and also the subsequent obtaining of cobalt and nickel through chelating resins. It was studied the reducing process of ferric iron and the effect of it in metals adsorption by ion exchange. Experiments of chemical reduction of ferric iron in solution were studied using sodium dithionite, sodium metabisulfite and sodium sulfite. Experiments with reducing agents sodium dithionite and metabisulfite were performed in São Paulo, and experiments with sodium sulfite were performed in The University of British Columbia. Reducing agents were added in ferric iron mono-elementary solution to decrease the redox potential. The variables potential redox, between 860mV and 240mV; pH, between 0,5 and 3,5; temperature, between 25°C e 60°C; and time, between 30min and 96 hours were studied in erlenmeyer flasks under constant stirring. Then, analyzed ferric iron reduction in multielementary solution of nickel laterite. In ion exchange experiments, performed in batch and column, it was used chelating resin Lewatit TP 207, with iminodiacetate functional group, and resin Lewatit TP 220, with bis-picolylamine functional group. Three solutions were studied: prepared with Fe(III), other with Fe(III) and the third with Fe(III) after pre-reducing process. Experiments in batch system were performed using erlenmeyer flasks, under constant stirring, with 100mL of solution to 1mL of resin. It was studied the effect of pH, between 0,5 and 3,5, time, between 30min and 480min, and temperature, between 25°C e 60°C. In experiments in continuous system, the three solutions were fed in glass columns filled with resin. The solution was fed using peristaltic pumps at constant flow rate. For column elution, sulfuric acid 1mol.L-1 was fed to the column using peristaltic pumps. The second part of this work, performed at The University of British Columbia, was the study of sodium sulfite application at prereducing process. It was studied two resins: Lewatit TP 207, selective for copper, and Lewatit TP 220, selective for nickel and cobalt. Sodium sulfite was added to the solution to decrease the potential, in flasks and it was placed under constant stirring. After reaction, the solution was placed in contact to the chelating resin, which was placed under stirring. Batch experiments were performed, and the effect of pH was studied between 0,5 and 3,5. In column process, the Column 1, filled with Lewatit TP 207, was used for copper removal, and output solution was feed in Column 2, filled with Lewatit TP 220. For the elution, it was studied sulfuric and hydrochloric acids in two different concentrations, 1mol.L-1 e 2mol.L-1. Sodium hydroxide was used for iron removal from solution obtained in Column 2 output. Cobalt separation was performed using solvent extraction technique (Cyanex 272 20%), studying the effect of pH, 4,0 and 5,0, and temperature, 25°C e 65°C. Results shows that ferric iron reduction using sodium dithionite was 100% in mono-elementary solution and 70% in multi-elementary solution with other metals. In ion exchange experiments performed in batch using resin TP 207, 62% of copper was adsorbed by the resin after pre-reducing process. For solution with Fe(II), the copper adsorption was 61%, and for solution with Fe(III), 49%. In ion exchange experiments after pre-reducing process using sodium sulfite, the copper adsorption was 69% at pH 2,0 by the resin TP 207. The resin TP 220 was more selective for nickel and cobalt at pH 2,0, where these metals adsorptions were 32,5% and 69%, respectively. In experiments performed in column, the Column 1 was used for copper removal, however there were losses of nickel (17%) and cobalt (7%). In the feeding of Column 2, it was found that 98% of nickel and 84% of cobalt were adsorbed. Solution obtained in Column 2 had concentration of iron 618mg.L-1, nickel was 13231mg.L-1 and cobalt 179mg.L-1. The iron removal was 100% at pH 4,0. For cobalt separation in nickel-rich solution, it was used the solvent extraction with Cyanex 272 20% with kerosene, where 99% of cobalt was separated from solution at 65°C and pH 5,0, without nickel loss. For future studies, the copper removal in the beginning of the process can be explored using other techniques, in order to avoid nickel and cobalt losses. Another point that can be explored is the maximum use of ion exchange columns in the same conditions of this work - solution with Fe(III), with Fe(II) and after the pre-reducing process - mostly on a pilot scale, to study the effect of iron oxidation state on possible resin poisoning.

Fiber-reinforced concrete (FRC) is nowadays extensively used in civil engineering throughout the world due to the composites of FRC can improve the toughness, flexural strength, tensile strength, and impact strength as well as the failure mode of the concrete. It is an easy crazed material compared to others materials in civil engineering. Concrete, like glass, is brittle, and hence has a low tensile strength and shear capacity. At present, there are different materials that have been employed to reinforce concrete. In our experiment, nanostructures iron oxide was prepared by electrodepostion in an electrolyte containing 0.2 mol/L sodium acetate (CH3COONa), 0.01 mol/L sodium sulfate (Na2SO4) and 0.01 mol/L ammonium ferrous sulfate (NH4)2Fe(SO4)2.6H2O under magnetic stirring. The resulted showed that pristine Fe2O3 particles, Fe2O3 nanorods and nanosheets were synthesized under current intensity of 1, 3, 5 mA, respectively. And the pull-out tests were performed by Autograph AGS-X Series. It is discovering that the load force potential of nanostructure fibers is almost 2 times as strong as the control sample.