abstract: Amazonia, inhabited and investigated for millennia, continues to astonish scientists with its cultural and natural diversity. Although Amazonia is rapidly changing, its vast and varied landscape still contains a complex natural pharmacopeia. The Amazonian tribes have accrued valuable environmental and geological knowledge that can be studied. This dissertation demonstrates that Indigenous Knowledge considered alongside Western Science can enhance our understanding of the relationship of people to geological materials and hydrological resources, and reveal mineral medicines with practical applications. I used methods from anthropology and geology to explore the geological knowledge of the Uitoto, a tribe of the Colombian Amazon. The Uitoto use two metaphors to describe Earth systems: 1. the earth is a body, and 2. the Amazon is a tree. I found that they classify surface-water systems according to observable characteristics and use mineral clays to treat various maladies. I argue that Uitoto knowledge about Amazonian mineral resources and surface water is practical, empirically–based and, in many cases, more nuanced than mainstream scientific knowledge. I studied the mode of action of a natural antibacterial clay from the Colombian Amazon (AMZ) to discover whether the Uitoto’s claims about the clay’s medicinal values was verifiable using the methods of Western Science. Natural antibacterial clays can inhibit the growth of human pathogens. Methods from microbiology and geochemistry were combined to evaluate the mineral-microbe interactions that inhibit growth of model Gram-negative (Escherichia coli) and Gram-positive (Bacillus subtilis) bacteria. The AMZ antibacterial clay contains 45 % kaolinites and 30 % smectites. Its high surface area maintains an acidic environment (pH 4.5) and releases high concentrations of aluminum. Aluminum accumulates in the outer membrane of E. coli by binding to phospholipids. Furthermore, the membrane’s permeability increases due to synergistic effects between aluminum and transition metals released from the AMZ (i.e. Fe, Cu). The changes in the membrane may compromise its function as a barrier. Understanding the antibacterial mechanism of AMZ is key for its safe use as a natural product. These findings can help us harness the capabilities of antibacterial clays more efficiently. Lastly, I integrated the results of this work in place-based, cross-cultural educational materials tailored for the tribal schools in the Colombian Amazon. The design of the units was informed by principles of curriculum design and successful pedagogic approaches for Native American students. The purpose of these educational materials is to return the results of research, enhance learning and participation of indigenous peoples in geosciences, and respond to the multicultural and plurilingual educational needs in countries such as Colombia. / Dissertation/Thesis / Doctoral Dissertation Geological Sciences 2016

Made available in DSpace on 2014-06-11T19:29:07Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-11-17Bitstream added on 2014-06-13T19:58:42Z : No. of bitstreams: 1 nunes_re_me_sjrp.pdf: 757996 bytes, checksum: a9d2dac5fa8e31e51dfe97f412131591 (MD5) / O presente trabalho está relacionado ao estudo da interação entre as argilas modificadas e compostos orgânicos aromáticos, visando à remoção destes por meio das propriedades de adsorção das argilas. As argilas foram submetidas aos processos de purificação, troca catiônica e também à técnica de pilarização. As propriedades obtidas, após os processos de modificações das argilas (microporosidade e adsorção de compostos orgânicos) foram analisadas no estudo da eficiência da adsorção dos compostos orgânicos, fazendo análises comparativas entre elas. Para análises, comparativas e caracterização das argilas, foram utilizadas as técnicas espectrofotométricas UV-Visível, Infravermelho, Difração de Raios X e Análise Térmica (TG-DTA simultâneos). As modificações constatadas foram: 1- a ocorrência da purificação com ácido clorídrico, troca catiônica (cátions Na+ natural das argilas) por cátions de Cu2+,Ca2+ e pilarização com íon Keggin (Al13); 2- aumento significativo da eficiência na adsorção dos compostos orgânicos antraceno e ácido 9-antróico em meio aquoso; 3- melhora da eficiência na adsorção dos compostos orgânicos aromáticos pelas argilas (KSF e STx-1) pilarizadas com o íon Keggin de alumínio (Al13), e 4 - melhora da adsorção, pelas argilas, do antraceno quando comparado ao ácido 9-antróico. As justificativas para as ocorrências descritas nos itens 3 e 4 foram: maior espaçamento basal das lamelas das argilas pilarizadas, maior caráter hidrofóbico e ausência do grupo carboxila, respectivamente. Os resultados mostraram ótima eficiência das argilas modificadas para a remoção dos compostos orgânicos (antraceno e ácido 9-antróico) presentes em água / This study is related to the study of interaction clays modified and organic aromatic compounds, aimed at removing these through the adsorption properties of clays. The clays were subjected to purification processes, and also the cation exchange technique pillarization. The properties obtained after the process of modification of clays (microporosity and adsorption of organic compounds) were analyzed to study the efficiency of adsorption of organic compounds, making comparative analysis between them. To comparative analyze and characterization of clays, spectrophotometric techniques were used UV-visible, infrared, X ray diffraction and thermal analysis (simultaneous TG-DTA). The changes observed were: 1 –the occurrence of purification with hydrochloric acid cation exchange (Na+ cations of natural clays) by cations Cu2 + and Ca2 + and pillarization with Keggin ion (Al13); 2 - significant increase in efficiency in the adsorption of organic compounds anthracite and 9-antróico acid in aqueous medium; 3 - improving the efficiency of adsorption of aromatic organic compounds by clays (KSF and STx-1) pillared with aluminum Keggin ion; 4 - improvement of adsorption by clays, anthracite compared to 9-antroico acid. The reasons for the occurrences described in items 3 and 4 were higher basal spacing of the lamellae of the pillared clays, the greater hydrophobic character and absence of the carboxyl group, respectively. The results showed great efficiency of modified clays for the removal of organic compounds (anthracite and 9-antroico acid) present in water

Orientador: Fernando Luis Fertonani / Banca: Cecília Cristina Marques dos Santos / Banca: Márcia Cristina Bisinoti / Resumo: O presente trabalho está relacionado ao estudo da interação entre as argilas modificadas e compostos orgânicos aromáticos, visando à remoção destes por meio das propriedades de adsorção das argilas. As argilas foram submetidas aos processos de purificação, troca catiônica e também à técnica de pilarização. As propriedades obtidas, após os processos de modificações das argilas (microporosidade e adsorção de compostos orgânicos) foram analisadas no estudo da eficiência da adsorção dos compostos orgânicos, fazendo análises comparativas entre elas. Para análises, comparativas e caracterização das argilas, foram utilizadas as técnicas espectrofotométricas UV-Visível, Infravermelho, Difração de Raios X e Análise Térmica (TG-DTA simultâneos). As modificações constatadas foram: 1- a ocorrência da purificação com ácido clorídrico, troca catiônica (cátions Na+ natural das argilas) por cátions de Cu2+,Ca2+ e pilarização com íon Keggin (Al13); 2- aumento significativo da eficiência na adsorção dos compostos orgânicos antraceno e ácido 9-antróico em meio aquoso; 3- melhora da eficiência na adsorção dos compostos orgânicos aromáticos pelas argilas (KSF e STx-1) pilarizadas com o íon Keggin de alumínio (Al13), e 4 - melhora da adsorção, pelas argilas, do antraceno quando comparado ao ácido 9-antróico. As justificativas para as ocorrências descritas nos itens 3 e 4 foram: maior espaçamento basal das lamelas das argilas pilarizadas, maior caráter hidrofóbico e ausência do grupo carboxila, respectivamente. Os resultados mostraram ótima eficiência das argilas modificadas para a remoção dos compostos orgânicos (antraceno e ácido 9-antróico) presentes em água / Abstract: This study is related to the study of interaction clays modified and organic aromatic compounds, aimed at removing these through the adsorption properties of clays. The clays were subjected to purification processes, and also the cation exchange technique pillarization. The properties obtained after the process of modification of clays (microporosity and adsorption of organic compounds) were analyzed to study the efficiency of adsorption of organic compounds, making comparative analysis between them. To comparative analyze and characterization of clays, spectrophotometric techniques were used UV-visible, infrared, X ray diffraction and thermal analysis (simultaneous TG-DTA). The changes observed were: 1 -the occurrence of purification with hydrochloric acid cation exchange (Na+ cations of natural clays) by cations Cu2 + and Ca2 + and pillarization with Keggin ion (Al13); 2 - significant increase in efficiency in the adsorption of organic compounds anthracite and 9-antróico acid in aqueous medium; 3 - improving the efficiency of adsorption of aromatic organic compounds by clays (KSF and STx-1) pillared with aluminum Keggin ion; 4 - improvement of adsorption by clays, anthracite compared to 9-antroico acid. The reasons for the occurrences described in items 3 and 4 were higher basal spacing of the lamellae of the pillared clays, the greater hydrophobic character and absence of the carboxyl group, respectively. The results showed great efficiency of modified clays for the removal of organic compounds (anthracite and 9-antroico acid) present in water / Mestre

A incorporação de nanocargas minerais e vegetais em matriz polimérica tem sido estudada, principalmente, com o objetivo de melhorar as propriedades de desempenho mecânico dos polímeros para aplicações industriais diversas. As argilas organofilizadas e as fibras vegetais estão entre os materiais que se destacam como cargas adicionadas ao polímero para a formação de nanocompósitos. Essa área de estudo tem despertado interesse também devido à obtenção de melhorias de propriedades físicas, químicas e mecânicas desses materiais quando comparadas às dos materiais compósitos tradicionais. O objetivo da pesquisa foi estudar algumas dessas propriedades em nanocompósitos produzidos com polipropileno, argila esmectítica brasileira e fibra do ouriço da castanha-do-brasil, com ênfase na melhora das propriedades mecânicas. Inicialmente, os materiais componentes foram caracterizados por diversos ensaios, tais como, difração de raios X, granulometria, infravermelho, microscopia eletrônica de varredura, temperatura de degradação térmica, além de ensaios específicos para medir características individuais da argila, como, viscosidade Fann, inchamento de Foster, limite de plasticidade, fluorescência de raios X, entre outros. Posteriormente, o polipropileno graftizado com anidrido maleico (PP-g-MA) foi incorporado ao PP puro (PP), em extrusora dupla rosca, nas proporções de 5%, 10% e 20% em peso e injetados os corpos de prova para os ensaios de tração e impacto. A partir dos resultados das propriedades mecânicas definiu-se o uso de 5% de PP-g-MA para preparação dos nanocompósitos definitivos. Finalmente, variou-se a quantidade de fibra na composição. Foram obtidos nanocompósitos de polipropileno (PP) e 5% PPg- MA reforçado com 5% em peso da argila organofilizada e fibra do ouriço da castanha-do-brasil em três proporções 5%, 10% e 15% em peso. As amostras foram caracterizadas por diferentes técnicas (DRX, MEV, FTIR, TG/DSC) e medidas as resistências mecânicas à tração, flexão e impacto. Todos os nanocompósitos apresentaram aumento na resistência mecânica quando comparados ao polímero sem argila e fibra. / The incorporation of vegetable and mineral nanofillers in polymer matrix has been studied mainly in order to improve the mechanical performance properties of polymers for various industrial applications. The organoclays and vegetable fibers are among the materials that stand out as fillers added to polymer for the formation of nanocomposites. This study has also attracted interest owing to achieve improvements in various properties when compared to other traditional composite materials. This study aims to investigate the effects of adding organophilic clay and brazilian nut fibers on the some physical, chemical and mechanical properties of polypropylene nanocomposite. Initially, The component materials were characterized by tests, such as X-ray diffraction, particle size, infrared, scanning electron microscopy, thermal degradation, as well as specific assays for measuring individual characteristics and properties of the clay, for example, viscosity Fann, Foster swelling, plasticity limit, X-ray fluorescence, among others. In the second step, the graftizado polypropylene with maleic anhydride (PP-g-MA) was incorporated into the pure PP, extruded in proportions of 5 weight%, 10 weight% and 20 weight% and injected the samples for tensile and impact tests. From the results of mechanical properties was defined using 5 weight% of PP-g-Ma for the incorporation into pure PP. Finally, samples were prepared containing only polymer, graftizado polymer/clay, graftizado polymer/clay/ fiber. The addition of clay was 5 weight% and the fiber was added to 5 weight%, 10 weight% and 15% by weight, respectively. The nanocomposites were prepared double-screw extruder and the samples injection molded, then, they were characterized by X-ray diffraction, scanning electron microscope (SEM), thermal analysis (TG/DSC), infrared spectroscopy and mechanical strength, flexural and impact test. All the nanocomposites increased mechanical properties as compared to polymer without clay and fibers.

El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / n this article, the geotechnical behavior of the reinforced soil is studied through additions of polypropylene fiber and recycled glass powder, this in order to obtain a homogeneously reinforced soil matrix to reduce possible structural failures, differential settlements and increase capacity bearing. The sample used was classified as a clay soil with low plasticity (CL) and with moderately expansive characteristics, based on the values of the Liquid Limit, Plastic Limit and Plasticity Index. The effect of the 1% polypropylene fiber and different amounts of recycled glass powder (0%, 4%, 5%, 6.5%), with respect to dry weight is analyzed in this soil. The purpose of varying the quantity of these materials is to find a trend of the strength parameters and obtain the optimal percentages that provides improvements in geotechnical behavior. Modified Proctor and Direct Shear tests were carried out, this latter to obtain the shear strength parameters of the mixtures and compare them with the clay soil. Finally, the optimal result for soil improvement was the mixture made by 1% polypropylene fiber and 4% glass powder, which achieved an increase of the angle of friction and cohesion.

Clay soils can be stabilized by the chemical reaction between the clay particles and lime to produce calcium aluminate and calcium silicate minerals. This cementation effect on clay particles result in increasing the strength of lime-treated clay soils. The mechanical strengths (compressive, tensile and shear strengths) of clay soils are improved from soft to stiff behavior by treating with lime and evolve along the curing time.An extensive experimental investigation has been carried out using laboratory reconstituted (compacted) expansive soils, covering a range of plasticity indices. Four selected soils with different fundamental physical and mechanical behaviors have been used to stabilize with lime. In addition to basic geomechanical characterization tests (modified proctor compaction, uniaxial compression strength, indirect tensile strength, oedometric compression, direct shear tests), a special focus was put on triaxial compression and extension tests upon drained and undrained conditions. Also, the development of swelling pressure upon wetting was also carefully investigated.The shear behavior of compacted clay soils is experimentally investigated by using both direct shear test and triaxial shear tests. These tests were conducted on saturated specimens for four selected soils. It is observed that the shear strength of both tests is evolving with addition of lime and with the plasticity index. In addition to the strength parameters, triaxial shear test was also used to determine the Young modulus of treated soils. It was noticed that the lime treatment increases the elastic modulus of selected clay soils.The triaxial compression system was modified to a triaxial extension system in order to evaluate the triaxial tensile strength of one of the tested soils (N1, from Quenast, Belgium). The pure tensile strength of soils can be determined from triaxial extension test at low confining pressures while high confining pressures induces shear failure.The failure criteria of lime-treated soils were studied in different stress planes to evaluate the shear and tensile strength obtained from triaxial extension test and triaxial compression test. A combined rupture criterion of original and modified Griffith criteria was applied. The results obtained from experimental testing have shown that at low confining pressures, the failure stress of extension test followed the Original Griffith Criterion started from pure tension, and at the higher confining pressures the failure stress followed the Modified Griffith (equivalent to Mohr-Coulomb, in this case).In application of this combined equation, the result of four selected soils obtained from triaxial tension test, direct shear test and triaxial compression test was plotted in the (sigma,to) in order to verify this equation. These experimental results match with the combined equation.This analysis revealed the strong interest of extension triaxial tests, with respect to more conventional indirect tension tests (also called splitting tests). Extension triaxial tests allow to control the drainage conditions and performed a full effective stress analysis of the stress-strain responses, including pre-failure behavior and ultimate strength criterion. Also, it provides a smooth transition between shear strength and tensile strength criterion, depending on the confining pressure of the test.At the end of this work, experimental results are analyzed and correlated with several parameters. Shear strength, compression index and swelling pressure were found to depend primarily on plasticity index for both treated and untreated materials. Many approaches in literature have also expressed these mechanical properties of soils in function of plasticity index. However, there are a few equations matching closely to testing results. For the development of swelling pressure upon wetting, a modified equation was proposed for experimental data for non-treated soils and lime-treated soils. / Doctorat en Sciences de l'ingénieur et technologie / info:eu-repo/semantics/nonPublished

La pollution des eaux usées par les éléments métalliques présents à l’état de traces et les cholorophénols pose un problème majeur pour l’environnement et la santé humaine. Cette étude concerne la synthèse d’argiles organophiles et de zéolithes à partir d’argiles naturelles prélevées en Tunisie et leurs applications pour l’adsorption respectivement des chlorophénols et des cations métalliques (Pb2+, Cd2+).Sur le plan de la synthèse d’argiles organophiles, une argile de type smectitique a été modifiée en utilisant le tensio-actif HDTMA. Cette argile organophile a été utilisée pour l’adsorption du 3-chlorophénol et du 4-chlorophénol. L’étude des isothermes et de la calorimétrie d’adsorption ont prouvé l’efficacité de cette argile organophile pour l’adsorption des deux chlorophénols.Des zéolithes ont été préparées à partir d’une argile naturelle composée de kaolinite, d’illite et de quartz. Ces zéolithes ont été utilisées pour l’adsorption des éléments métalliques tels que la cadmium (Cd2+) et le plomb (Pb2+) . Les cinétiques et les isothermes d’adsorption de Cd2+ et Pb2+ sur les zéolithes synthétisées (CAN, ANA, mélange Faujasite (FAU), néphéline et quartz), une cancrinite naturelle, une zéolithe commerciale (FAU 13X) et l’argile de départ ont été étudiées à 25°C en utilisant la méthode des restes. Une étude calorimétrique a été faite pour mieux comprendre les phénomènes mis en jeu lors de l’adsorption. La cinétique d’adsorption est très rapide. Une meilleure affinité est obtenue pour les zéolithes. / This study concerns the synthesis of zeolites and organophilic clays from clay and their applications for the adsorption of metallic elements (Pb2+, Cd2+) and chlorophenols.In terms of the synthesis of organophilic clays, a smectite clay was modified using the HDTMA surfactant. This organophilic clay was used for the adsorption of 3-chlorophenol and 4-chlorophenol. The study of isotherms and adsorption calorimetry have proved the effectiveness of this organophilic clay for the adsorption of the two chlorophenols.By hydrothermal high-pressure synthesis of zeolites, from natural clay composed of a fraction of kaolinite, illite and quartz, two types of zeolites were synthesized with good purity, a cancrinite (CAN) type zeolite and the other analcime (ANA) type; other type of zeolite was synthesized such as faujasite 13X but the purity and reproducibility was limited.These three types of zeolite (CAN, ANA and FAU 13X) were tested for the adsorption of Pb (II) and Cd (II). A better affinity of the zeolites synthesized than the starting clay with respect to the two metallic cations (Pb (II) and Cd (II)). The study of the adsorption kinetics of Pb (II) and Cd (II) showed rapid adsorption of the two metallic cations studied on the different types of zeolites. The results proved that the synthesized zeolites were a very promising materials for the adsorption and removal of heavy metals in water.

Unlike other thermo-mechanical soil responses, the effects of temperature on residual shear strength of soils are not well understood. Previous studies on temperature effects on residual shear strength show some contradictory findings that might be attributed to the sample's mineralogical composition and the testing procedure. This thesis aims to contribute to the understanding of (1) the temperature effects on the liquid limit of cohesive soils, (2) the impact of testing procedure on temperature-dependent residual friction angle, and (3) temperature effects on residual friction angle of soils. The fall cone tests are used to determine temperature effects on the liquid limit, while a temperature-modified ring shear apparatus is used to evaluate the residual friction angle in this study. To assess the impact of the testing procedure, the temperature is changed to 50°C at three different instants: before consolidation, before preshearing, and after preshearing; the resulting residual friction angles are assessed and compared. The effects of temperature on residual friction angle of soils are also investigated by changing the temperature in the ring shear apparatus to 10°C, 20°C, 40°C, and 50°C before consolidation. The study found that the impacts of temperature on liquid limit is mineralogy dependent. Also, the instant at which temperature change occurs in ring shear tests was found to be insignificant in terms of the residual friction angle. Moreover, the findings of the ring shear experiments suggest that clay mineralogy is important in the study of temperature-dependent residual friction angle of cohesive soils. Antigorite-rich soils may experience up to 50% changes in their residual friction angle, while soils with other clay minerals may experience less than 20% variations over a temperature range from 10 to 50 °C. / Master of Science / The increase in the frequency of landslides was found to be attributed to seasonal variation in temperature and an increase in global temperature due to climate change. To anticipate, mitigate and adapt to this costly natural disaster, understanding soil response to temperature change is an essential step. The residual shear strength of a soil is a parameter used to analyze stability of landslides. The relationship between this residual shear strength and temperature is not well understood. Previous studies on temperature effects on residual shear strength show some contradictory findings that need to be better understood for a more robust assessment of the climate change impacts on the stability of natural and man-made slopes. This thesis represents a first step to fill the knowledge gap in identifying the temperature effects on the residual shear strength of soils so that the impact of climate change and seasonal variation in temperature on slopes can be assessed more rigorously. This study consists of three tasks. The first task is to assess the effects of temperature on liquid limit, a parameter widely used to estimate the residual shear strength. The second task is to investigate the impacts of the testing procedures on residual shear strength, representing three field conditions where temperature change takes place at three different instants: when the soils is consolidating under applied load, after the soil consolidated and before development of a failure plan, and after failure initiated. The last task is to assess the effects of temperature on residual shear strength of soils. From the study, it was found that the effects of temperature on liquid limits and residual shear strength are dependent on the soil's mineralogical composition. It was also found that the instant in which the temperature changes in the testing procedure does not substantially impact the residual friction angle of the soil.

Made available in DSpace on 2017-07-24T19:37:53Z (GMT). No. of bitstreams: 1 Caetano, Elenice Hass.pdf: 4149328 bytes, checksum: b6eb52279243079ec9a5d88b5028ae4c (MD5) Previous issue date: 2015-03-02 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Clay minerals are hydrated silicates of Aluminum, Iron and Magnesium that has lamellar structure (phyllosilicates) composed by continuous SiO4 tetrahedral layers connected to bi and tri metals hydroxide octahedral layers. The layers are continuous and hexagonally ordered regarding to crystallographic axis a and b. The arrange of clays minerals determines the type of clay mineral as 1:1 or 2:1. The 2:1 clays minerals are divided in groups: Vermiculite, Mica, Chlorite, Saponite, Paligorskita and the Smectite group. Among the Smetectite group stands out the Bentonite, the most abundant clay mineral and that shows 2:1 phyllosilicates structure composed by two silicate tetrahedral layers and one alumina octahedral layers, both connected by oxygen atoms in common. The great technological interest in these clay results of the high cation exchange capacity, swelling by water and low size of crystals. Such properties favor the clays modification to discovery new applications. Thus, the clays minerals are an essential step for the discovery of technological applications as well as the fundamental properties of clays. In this work, were characterized four samples of clays through of X-Ray Diffraction, X-Ray Fluorescence Spectroscopy, Fourier Transform Infrared Spectroscopy, 27Al NMR-MAS and Field Emission Scanning Electron Microscopy. The obtained results indicate the predominance of Smectite phase in clays due to high swelling capacity and cation exchange observed. The predominance of Smectite phase was confirmed by XRD, XRF and FTIR, which also indicates the presence of quartz and other minerals. Were also evaluated the presence of organic compounds in the interlayer space of modified clays and was noted that have not changes in their crystalline structures, based on FTIR and 27Al NMR-MAS results. The SEM-FEG micrography confirms the irregularity of cluster size, according to expect to bentonite clays. The performed characterizations for these clays minerals determine its elementary composition and makes possible distinguish the four samples according to its place of origin by the amount of impurities, as well as the prevalence of smectite phase. The characterization analysis were used to quantification of fundamental properties and to evaluated the organic compounds presence in interlayer space through of delocalization of the most intense peak in 2θ angle. The obtained results are useful for the benefit of industrial areas such as pharmaceutical, food, environmental and others, once the mineral clays properties can be improved when properly identified and quantized. / Argilas são materiais naturais, terrosos, considerados finos grãos que contém partículas com diâmetro inferior a 2 μm e, quando umedecidos com água, apresentam plasticidade. São constituídas essencialmente por argilominerais (filossilicatos) e por matéria orgânica, sais solúveis, minerais como calcita, pirita, gibsita, quartzo entre outras impurezas. Bentonita, conhecida como o argilomineral mais abundante do grupo da esmectita, pertence ao grupo dos filossilicatos 2:1, sua estrutura cristalina é constituída por duas folhas tetraédricas de sílica com uma folha central octaédrica de alumina, ambas unidas por átomos de oxigênio em comum. O grande interesse tecnológico nessa argila está ligado à sua alta capacidade de troca catiônica, intumescimento pela água e às pequenas dimensões dos cristais, cujos fatores favorecem a modificação das argilas para a descoberta de novas aplicações. Para tanto, a caracterização da argila é uma etapa primordial para aplicações tecnológicas bem como suas propriedades fundamentais como alta adsortividade, alta capacidade de troca catiônica, capacidade de inchamento e alta propriedade de barreira. No presente trabalho, foram caracterizadas quatro amostras de argilas Bentonítas de diferentes procedências, sendo duas na sua forma pura e duas organofílicas pelas respectivas técnicas: difração de raios X, fluorescência de raios X, Espectroscopia Vibracional de Absorção na Região do Infravermelho, Ressonância Magnética Nuclear do estado sólido - 27Al RMN-MAS, Microscopia Eletrônica de Varredura com Efeito de Campo. Os resultados obtidos indicaram a predominância da fase esmectita evidenciada pela alta capacidade de inchamento e alta capacidade de troca catiônica. Além disso, os resultados de DRX, FRX e FTIR também evidenciaram a predominância da fase esmectita, bem como a presença de quartzo e outros minerais. Também foi possível avaliar a presença de compostos orgânicos no espaço interlamelar das argilas organofílicas e notou-se que não houve alterações em suas estruturas cristalinas, informações estas corroboradas pelas técnicas de FTIR e 27Al RMN-MAS. As micrografias obtidas por MEV-FEG puderam confirmar a irregularidade de tamanho dos aglomerados de partículas típico de bentonitas. As Caracterizações obtidas para as argilas determinaram sua composição elementar, sendo possível distinguir argilas de diferentes procedências pela quantidade de impurezas, bem como a predominância da fase esmectita. Além disso, por meio da caracterização também foi possível determinar a quantificação de suas propriedades fundamentais, e também confirmar a presença de composto orgânico no espaço interlamelar por meio do deslocamento do pico de maior intensidade do ângulo 2θ. Essas caracterizações podem ser utilizadas em benefício das áreas industriais, como farmacêutica, alimentícia, ambientais entre outras, podendo ser aprimoradas as propriedades quando bem identificadas e quantizadas.

Neste estudo, investigaram-se mudanças nas propriedades coloidais de uma esmectita pilarizada com polihidroxicátion de alumínio. A solução pilarizante foi preparada mediante gotejamento de solução NaOH 0,4 mol L-1 em solução de AlCl3.6H2O 0,2 mol L-1, a qual foi adicionada à suspensão de argila de 1% m/m. Para avaliar mudanças nas propriedades das argilas, recorreu-se às técnicas de titulação potenciométrica descontínua, análise química total, DRX, FTIR, CTC e isotermas de adsorção/dessorção de N2. Além disso, foram realizados ensaios de adsorção de Cu2+ para avaliar a capacidade de remoção do metal de soluções aquosas pelas argilas pilarizadas e gerar informações relacionadas à interação entre adsorvente e adsorbato. Naturalmente, a argila apresentou espaçamento basal de 1,26 nm, ao passo que as pilarizadas apresentaram valores de 1,78 nm (500 oC) e 1,80 nm (350 oC). Dados da análise química total mostraram se tratar de uma montmorillonita com altos teores de Fe3+, e confirmou o aumento nos teores de Al3+ na estrutura da argila após pilarização. Os valores de área superficial específica e volume de microporos foram maiores para as argilas pilarizadas, enquanto que a CTC foi maior para a argila natural. A titulação potenciométrica mostrou modificação nas curvas de titulação com o processo de pilarização, em que nas argilas pilarizadas surgiram novos sítios de reação. Dentre as equações de adsorção aplicadas, Langmuir, Freundlich e Temkin, a primeira apresentou valores de r2 das equações linearizadas maior para todas as argilas e menor desvio médio (?g%) para argila natural, ao passo que a equação de Temkin mostrou valores de ?g(%) menores para as argilas pilarizadas. Parâmetros termodinâmicos confirmaram que a reação de adsorção de Cu2+ é espontânea para todas as argilas, principalmente para as argilas pilarizadas. Além disso, cálculos baseados em equações de Dubinin-Radushkevich evidenciam que a ligação é fraca entre metal e argila, caracterizando reações de fisissorção. / In this study, an Al-pillared smectite was synthesized and changes in its colloidal properties were investigated. The pillaring solution was prepared adding dropwise adequate volume of NaOH 0,4M to AlCl3.6H2O 0,2M solution. Then, the pillaring solution was added to a 1% w/w clay slurry with constant stirring. Potentiometric titration, chemical analysis, XRD, FTIR, CEC and N2 sorption/dessoption isotherms analysis were done to characterize the changes in clay properties. Moreover, adsorption experiments were carried out in order to evaluate the capacity of the pillared clays to remove Cu2+ from aqueous solution and to characterize the interaction between adsorbent and adsorbate. The natural clay has a basal spacing of 1.26 nm whereas the pillared clays reached 1.78 nm (500 oC) and 1.80 nm (350 oC) after calcination. Chemical analysis revealed that the montmorillonite used has high content of Fe3+ and the increase in the Al3+ amount in the structure of the pillared clays after pillaring process. The surface area and micropore volume were higher for the pillared clays and the CEC was higher for the natural clay. The pillaring process changed the potentiometric titration curves, wherein the pillared clays exhibited new reactive site. Experimental data were fit to Langmuir, Freundlich and Temkin adsorption equations, being the the first one the best (highest r2 value) for all the clays and lower standard deviation (?g%) for the natural clay. On the other hand, Temkin equation exhibited ?g% value lower for the pillared clays. Thermodynamics parameters demonstrate that the Cu2+ adsorption process is spontaneous for all the clays, but with higher values for the pillared materials. In addition, application of the Dubinin-Radushkevich equation revealed that the bond between the metal and the clay are weak, characterizing a physisorption.