Statybos pramonėje, mišiniuose vis plačiau naudojamas įvairus tiek natūralių tiek sintetinių ceolitų spektras. Atliktuose tyrimuose buvo naudojamas sintetinis ceolitas – hidrosodalitas (Na6+x(SiAlO4)6(OH)x•nH2O), modifikuotas hidrosodalitas ir fero silicio gamybos atlieka - SiO2 mikrodulkės. Su pastaraisiais pucolaniniais priedais tiriama sąveika su cementu, nustatyta kaip keičiasi cemento stiprio, tankio ir įgėrio savybės. Tyrimai atlikti ruošiant bandinius su 2%, 5%, 10% ir 15% pucolaninių priedų masės santykiais. Atlikus tyrimus nustatyta, kokia daroma įtaka cementinės masės hidratacijos temperatūrai. Nustatytas bandinių stiprumas, tankis po 3, 7 ir 28 parų. Nustatytas bandinių įgėris po 28 parų. Cementinio akmens gniuždomasis stipris nenaudojant priedo ir ilginant hidratacijos trukmę nuo 3 iki 28 parų didėja nuo 59 iki 80 MPa. Panaši priklausomybė stebima ir cementiniuose bandiniuose su pucolaniniais priedais. Ilgėjant hidratacijos trukmei stipriai gniuždant didėja. Tirtose sąlygose didžiausią stiprį gniuždant turėjo bandiniai su 10 % modifikuoto hidrosodalito priedo po 28 parų, gniuždomasis stipris padidėja iki 101 MPa. Galima daryti prielaidą, kad hidrosodalito, modifikuoto hidrosodalito ir SiO2 mikrodulkių pucolaninės savybės pasireiškia ne iš karto, bet išryškėja po ilgesnes hidratacijos trukmės, t. y. po 28 parų. Vykstant hidratacijai nuo 16 iki 28 parų, įgėris sumažėja nuo 13,41% iki 9,04% (esant 2% hidrosodalito kiekiui). Naudojant 5% SiO2 mikrodulkių kiekį... [toliau žr. visą tekstą] / Construction industry is increasingly being used in combination and variety of natural and synthetic zeolites spectrum. A study carried out using synthetic zeolite - hydrasodalite (Na6 + x (SiAlO4) 6 (OH) x • nH2O) modified hydrasodalite silicon production and Fair play - fume SiO2. With the recent pozzolanic additives investigated the interaction with cement, concrete changes in the strength, density and retention properties. Studies carried out in the preparation of the samples with 2%, 5%, 10% and 15% by weight of pozzolanic additives relations. It was determined, which affect the weight of cement hydration temperature. Fixed specimens the strength and the density of 3, 7 and 28 days. Set of samples absorption after 28 days. Compressive strength of cement stone without the use of additive and longer duration of hydration from three to 28 days increased from 59 to 80 MPa. A similar dependence is observed in samples with cement and pozzolanic additives. Hydration with increasing duration of the compressive strength increases. To examine the conditions had the highest compressive strength of samples with 10% modified hydrasodalite additives after 28 days, compressive strength increases to 101 MPa. It can be assumed that hydrasodalite, and SiO2 modified hydrasodalite fume pozzolanic properties are not immediate, but come on after a longer duration of hydration, etc. Y. after 28 days. During the hydration from 16 to 28 days, absorption decreases from 13.41% to 9.04% (at 2%... [to full text]

ZSM-5 is an aluminosilicate zeolite with high Si/Al ratio with suitable properties for catalysis, ion exchange, adsorption and membrane applications. The main goal of this thesis was to study the growth of ZSM-5 zeolite crystals from inexpensive natural sources of silica and alumina, as well as n-butylamine (NBA) as a low-cost structure directing agent. The first objective of this work was to develop pathways to synthesize ZSM-5 crystals from kaolin clay or diatomaceous earth, two inexpensive natural sources of silica and alumina (Paper I). In the case of kaolin, a heat treatment was used in order to form amorphous metakaolinite. Subsequently, dealumination of the raw materials by acid leaching made it possible to reach appropriate Si/Al ratios and to reduce the amount of impurities. Finally, leached metakaolinite or diatomaceous earth was reacted with sodium hydroxide and NBA. After synthesis optimization, both sources of aluminosilicates were found to behave differently during the course of synthesis and to lead to slightly different reaction products. The final products exhibited Si/Al ratios in the range 10-20. The use of leached diatomaceous earth allowed to reach higher yield of ZSM-5 crystals within comparable synthesis times. However, low amounts of mordenite were inevitably formed as a by-product, which was related to the high calcium content of diatomaceous earth. Therefore, the rest of the thesis focused on the kaolin system. In order to study the growth mechanism of ZSM-5 from leached metakaolinite, a proper methodology to gain local compositional data by energy dispersive spectroscopy (EDS) on aluminosilicates was developed (Paper II). Zeolite A was used as a model system that could be ion-exchanged with various elements. In order to evaluate the reliability of the measurements, inductively coupled plasma-sector field mass spectrometry (ICP-SFMS) and EDS were compared. The EDS method developed in this work resulted in molar ratios very close to theoretical values and was therefore found more reliable than ICP-SFMS. Therefore, the method developed for zeolite A was applied in the rest of the thesis work to study the formation and growth of ZSM-5 crystals. The second part of this work focused on the kaolin system in order to understand the nucleation and growth processes of the ZSM-5 crystals. This system was heterogeneous, due to the formation of a gel upon heating of the synthesis mixture. First, the internal structure of the gel was investigated (Paper III). Second, a kinetic study was performed and compared with microstructural observations (Paper IV). Finally, the mechanisms leading to Al-zoning and dendritical growth of the zeolite crystals were investigated (Paper V). The characterization of the intermediate phases during the different stages of the hydrothermal synthesis were analyzed by different analytical techniques, such as inductively coupled plasma-sector field mass spectrometry (ICP-SFMS), dynamic light scattering (DLS), extreme high resolution-scanning electron microscopy (XHR-SEM), energy dispersive spectroscopy (EDS), high resolution-transmission electron microscopy (HR-TEM), X-ray diffraction (XRD) and nitrogen gas adsorption. These investigations led to several important conclusions: 1) The walls of the gel were shown for the first time to be inhomogeneous and to possess a biphasic internal structure consisting of a mesoporous skeleton of aluminosilicate nanoparticles embedded in a silicate-rich soluble matrix of soft matter. 2) The kinetic study and microstructural evidences indicated that the early crystals were fully embedded inside the gel phase and that crystal growth was retarded, as the formation of the gel occurred simultaneously with the early growth of the crystals. Hence, nucleation and growth appeared to be solution mediated.  3) Finally, the Al zoning of the crystals was related to the biphasic internal structure of the gel, since the silicate-rich matrix was preferentially consumed first. 4) The dendrites present at the surface of the crystals during most of the growth process were shown to be caused by the presence of a web of nanoparticles, most likely originating from the mesoporous skeleton inside the gel. In the future, these findings are expected to lead to optimized synthesis pathways of catalysts with homogeneous properties and to contribute to the development of poor regions in Bolivia.

Les zéolithes sont des matériaux aluminosilicates nanoporeux largement utilisés dans l'industrie pour la filtration de l'eau, la séparation de gaz et le craquage des bruts pétroliers. Leurs propriétés d'adsorption et de catalyse sont reliées à la géométrie de leur réseau poreux d'une part et aux cations qui sont présents à leur surface d'autre part. Dans cette thèse, nous étudions par simulation moléculaire l'adsorption de molécules polaires, i.e. l'eau et le méthanol, dans deux zéolithes sodiques de type Faujasite. L'objectif de ce travail est d'étudier l'effet de la présence de molécules adsorbées sur la position et la dynamique des cations sodium et inversement l'effet des cations sur l'adsorption et la diffusion des molécules d'adsorbat. Nous nous sommes tout d'abord attachés à simuler par la méthode Monte Carlo le processus d'adsorption en fonction de plusieurs paramètres: i) répartition et densité des substitutions Si/Al, ii) valeur des charges électriques portées par le réseau zéolithique et iii) nature des potentiels d'interaction. Nous avons ainsi pu simuler les isothermes et les chaleurs d'adsorption d'une part et d'autre part la redistribution cristallographique des cations en fonction du nombre de molécules adsorbées, Nous nous avons ensuite porté notre intérêt à l'aide de la méthode de Dynamique Moléculaire, aux propriétés dynamiques (diffusion, transport) du système molécules adsorbées/cations/zéolithe. L'originalité de ce projet réside dans l'utilisation de ces deux techniques complémentaires qui permettent d'accéder aux propriétés thermodynamiques, structurales et dynamiques de tels systèmes. Les résultats de ces simulations sont comparés, en particulier, à ceux obtenus expérimentalement par Spectroscopie de Relaxation Diélectrique. / Zeolites are nanoporous aluminosilicate materials which attract a great deal of attention because of their use in industry for water filtration, phase separation and for cracking of crude oil. Their adsorption and catalysis properties depend on their pores geometry and on the cations which are located at their surface. In this work, we study by means of molecular simulation techniques the adsorption of polar molecules, i.e; water and methanol, in two zeolites type Faujasite. The aim of this study is to determine, on the one hand, the effect of the adsorbate on the cation distribution and dynamics at the surface of the zeolite and, on the other hand, the effect of the cation density on the adsorption and diffusion of the adsorbate molecules. We first simulate by Monte Carlo methods the adsorption of water and methanol and investigate the influence of several parameters: i) localisation and density of Si/Al substitution, ii) electrical charges at the nanopore surface and iii) expression of the interaction potential between the various atoms of the considered system. We thus calculated isotherms and heat of adsorption as well as the crystallographic re-localisation of the sodium cation as a function of the adsorbed molecule loading. . Then, we study by Molecular Dynamics the dynamics of the system adsorbate/cations/zeolite. The originality of this project lies in the use of both Molecular Dynamics and Monte Carlo techniques, which are complementary to study the thermodynamic, structural and dynamical properties of confined systems. Our simulation results are compared with those obtained by means of Dielectric Relaxation Spectroscopy experiments.

[pt] A zeólita MCM-22 foi desenvolvida por pesquisadores da Mobil em 1990. É um aluminossilicato com características de peneira molecular e com amplas aplicações em processos catalíticos devido a sua estrutura de dois sistemas de canais independentes. Neste trabalho, as condições reacionais de preparação desta zeólita utilizando tratamento hidrotérmico estático e sob agitação foram estudadas. A composição molar das amostras foi mantida enquanto a temperatura e o tempo de tratamento hidrotérmico ao qual o gel foi submetido foram variados. Os materiais obtidos foram caracterizados usando técnicas analíticas de difração de raios-X com refinamento de Rietveld, adsorção física de nitrogênio (BET), espectroscopia no infravermelho, análise química (espectrometria de absorção atômica), ressonância magnética nuclear (RMN), microscopia eletrônica de varredura e de transmissão. A zeólita MCM-22 característica foi obtida apenas com tratamento hidrotérmico sob agitação. As amostras obtidas a partir do tratamento hidrotérmico estático apresentaram fases como ferrierita, ZSM-5 e quartzo. A morfologia das amostras, observada por microscopia eletrônica de varredura, varia dependendo do tratamento adotado, estático ou sob agitação. Estas diferenças refletem diretamente nas áreas específicas dos materiais. Porém, não se observou diferenças relevantes no volume de poros dos materiais sintetizados sob sistema estático, exceto a amostra obtida com 5 dias de síntese, a qual possui fase amorfa presente. Apesar das fases contaminantes presentes, a microscopia eletrônica de transmissão permite ver o crescimento dos cristais nas três direções. Através dos espectros de infravermelho pode ser observada a eliminação do direcionador orgânico e o caráter hidrofílico da zeólita após o processo de calcinação. / [en] MCM-22 zeolite was first synthesized by Mobil researchers in 1990. It is an aluminosilicate with molecular sieve characteristics and several applications in catalytic processes because of its two independent pore systems. In this work, the MCM-22 zeolite synthesis conditions were studied using both static as stirred hydrothermal treatment. Molar composition of synthesis gel was fixed while the temperature and the gel aging time were varied. The products obtained were characterized using analytical techniques of X-ray diffraction with Rietveld refining, nitrogen adsorption (BET), infrared spectroscopy, atomic emission spectrometry, nuclear magnetic ressonance spectroscopy (NMR), scanning electronic microscopy (SEM) and transmission electronic microscopy (TEM). Typical MCM-22 zeolite was only obtained from hydrothermal treatment in stirring conditions. Samples obtained by static conditions showed contamination with ferrierita and ZSM-5 zeolites and quartz. The morphology of the samples, as showed by scanning electron micrographs, changed according the conditions of hydrothermal treatment, static or stirring. These differences affected the BET surface areas of obtained samples. However, no differences were observed in pore volume in samples obtained by static system, except the sample synthesized in 5 days, which presented an amorphous phase. Although, there were contaminant phases, transmission electron micrographs permitted to observe the crystal growing in the three directions. Trough infrared spectra it could be observed the template elimination and the zeolite hydrophilic nature after process calcination.

Amostras de cinzas geradas na combustão do carvão e de cinzas provenientes da queima dos resíduos da cana-de açúcar foram usadas como fonte de silício e alumínio para sintetizar zeólita 4A pelos métodos IZA e fusão alcalina seguida de tratamento hidrotérmico. A razão molar de Si/Al para a formação da zeólita foi ajustada pela adição de resíduo de alumínio da indústria terciária como fonte alternativa de alumínio. Os efeitos da temperatura, do tempo de fusão e o tempo da reação hidrotérmica foram investigados. Os resíduos e os produtos sintetizados foram caracterizados por diferentes técnicas, tais como: fluorescência de Raio X, difração de Raio X, capacidade de troca catiônica, entre outros. A zeólita sintetizada a partir de cinzas leves de carvão foi usada para a remoção de Cd2+ e Zn2+ de solução aquosa em sistema de batelada. Os dados de equilíbrio de adsorção foram avaliados usando-se equações não lineares dos modelos de Langmuir, Freundlich, Temkin e Dubinin-Radushkevich (D-R). Os modelos de D-R e Freundlich foram os que melhor se ajustaram aos dados experimentais do Cd2+ e Zn2+, respectivamente. A capacidade máxima de adsorção foi de 78,0 mg.g-1 para o Cd2+ e 35,8 mg.g-1 para o Zn2+. Os resultados mostraram que o resíduo de alumínio e as cinzas de carvão e de biomassa podem ser usados como matéria prima para obtenção de zeólita 4A, considerado um material de valor agregado e com promissoras propriedades de adsorção. / Ash samples generated in the combustion of coal and ash from the burning of sugarcane residues were used as a source of silicon and aluminum to synthesize zeolite 4A by IZA and alkaline fusion followed by hydrothermal treatment. The Si/Al molar ratio for zeolite formation was adjusted by the addition of aluminum residue from the tertiary industry as an alternative source of aluminum. The effects of temperature, melting time and hydrothermal reaction time were investigated. The residues and the synthesized products were characterized by different techniques, such as: X-ray fluorescence, X-ray diffraction, cation exchange capacity, among others. The zeolite synthesized from fly ash was used to remove Cd2+ and Zn2+ from aqueous solution in a batch system. The adsorption equilibrium data were evaluated using non-linear equations of the Langmuir, Freundlich, Temkin and Dubinin-Radushkevich (D-R) models. The D-R and Freundlich models were the best fit for the experimental data of Cd2+ and Zn2+, respectively. The maximum adsorption capacity was 78.0 mg.g-1 for Cd2+ and 35.8 mg.g-1 for Zn2+. The results showed that the coal and biomass ashes mixed with aluminium residues can be used as feedstock to obtain 4A zeolite, considered a value-added material with promising adsorption properties.

Afin de satisfaire à un cahier des charges toujours plus exigeant, l'industrie spatiale se doit d'innover en permanence, notamment dans le domaine du maintien des performances. De fait, la minimisation de la contamination moléculaire, qui provient du dégazage sous vide des matériaux constitutifs du satellite, permet d'éviter une baisse progressive des performances de ce dernier. En effet, les molécules organiques issues de ce dégazage peuvent se déposer sur les optiques ou les revêtements de contrôle thennique, altérant ainsi leur fonctionnement. De par leur porosité contrôlée, les zéolithes possèdent des propriétés compatibles avec une utilisation en orbite. Le principal obstacle à l'utilisation de ces matériaux concerne leur mise en forme. Contrairement aux poudres, les films zéolithiques permettent d'éviter la génération de poussières et présentent une meilleure durabilité tout le long de la mission en orbite.Le but de ce travail est d'étudier les propriétés d'adsorption de différentes structures zéolithiques vis-à-vis de divers polluants organiques Des films de zéolithes de types BEA et FAU ont été déposés sur des supports en verre et en fibres de carbone, respectivement. Dans les deux cas, des films homogènes, dotés d'une épaisseur compatible avec une utilisation en orbite, ont été obtenus. Les quantités adsorbées par les films ont été comparées à celles des poudres zéolithiques correspondantes. Il ressort de cette étude que les capacités d'adsorption sont légèrement plus faibles pour les films que pour les poudres, en raison de la présence de barrières diffusionnelles dans les films. Cependant, des études de désorption menées sous vide et en température ont établi que les films présentaient de meilleures capacités de rétention que les poudres, confirmant leur applicabilité dans le domaine de la décontamination moléculaire en orbite. / Molecular contamination control has been described as a key parameter for the optimization of on-orbit satellit functioning. In space conditions, the outgassing of organic pollutants jeopardizes the performances of certain instrument by contaminating critical surfaces such as thermal radiators and optical systems. The chemical nature of these pollutant has been investigated by the NASA, which listed the most frequent ones in a table. Several types of outgassed molecule were identified, mainly deriving from plasticizers (phthalates, adipates...). Moreover, elastomers, adhesives and other compounds such as hydrocarbons were also found in important quantities.In order to minimize the molecular contamination, techniques involving pre-flight bakeouts were set up, but rapidly proved to be expensive and time-consuming, as an important number of outgassing cycles was required to efficiently decrease the molecular contaminationThat is why other porous materials had to be investigated, highlighting zeolite relevancy for satellite decontamination.These aluminosilicate materials exhibit an ordered molecular-sized porous network which induces high sorption properties and an outstanding size and shape selectivity. Another topic of interest deals with the shaping of zeolite for their use in space conditions. Unlike powder materials, zeolite films avoid the generation of dust particles in low earth orbit and can be easily embedded in appropriate areas throughout the lifetime of the mission.This work deals with the preparation of zeolite films and the adsorption of organic contaminants onto their surface. Zeolite beta and faujasite films were prepared on glass substrates and carbon fibers, respectively. The sorption properties towards several alkanes and aromatic molecules were investigated and the performances compared to the powders counterparts. It was shown that the films presented slightly lower sorption properties in comparison to powders, due to diffusional barriers. Nevertheless, the properties were satisfactory in respect to the requirements of space industry.

Atualmente o mundo vem passando por algumas mudanças climáticas, sendo que um dos fatores que contribuem para essas mudanças é o aumento da emissão de gases de efeito estufa, principalmente o CO2. Uma das fontes de CO2 é a queima de combustíveis fósseis. A combustão do carvão para produção de energia, além de emitir gases de efeito estufa, gera uma grande quantidade de cinzas. A utilização das cinzas de carvão para síntese de zeólitas de alta pureza e utilização dessas zeólitas para a adsorção do CO2 pode ser uma estratégia interessante para mitigar a problemática da gestão de resíduos e da emissão de gases. O objetivo deste trabalho foi sintetizar e caracterizar zeólitas tipo Na-A de elevada pureza a partir de cinzas de carvão e avaliar sua aplicação como material adsorvente de CO2. As amostras de três tipos de cinzas de carvão (cinzas manga, cinzas ciclone e cinzas pesadas) foram coletadas na usina termelétrica de Figueira-PR. O tempo total do processo de síntese pelo método de duas etapas foi otimizado. As seguintes características dos produtos de síntese foram determinadas: composição mineralógica, composição química, morfologia, grupos funcionais e capacidade de troca iônica. Os produtos de síntese apresentaram relação SiO2/Al2O3 de 1,2 e uma relação de aproximadamente 80% de zeólita do tipo Na-A. As zeólitas foram usadas como material adsorvente de gás carbônico apresentando capacidade de adsorção entre 492 a 655 mg/g. A maior capacidade de adsorção foi obtida com a zeólita sintetizada a partir das cinzas pesadas. As zeólitas saturadas mostraram-se estáveis em temperatura ambiente e a dessorção do CO2 ocorreu entre 140-150 °C. / Currently the world is undergoing some climate change, one of the factors that contribute to these changes is the increase in greenhouse gas emissions, especially CO2. One of the sources of CO2 is the burning of fossil fuels. The combustion of mineral coal for energy production, in addition to emitting greenhouse gases, generates a large amount of ash. The use of coal ash for the synthesis of zeolites and the use of these zeolites for the adsorption of CO2 can be an interesting strategy to mitigate the problems of waste management and the emission of gases. The objective of this work was to synthesize and characterize high purity Na-A zeolite from coal ash and evaluate its application as a CO2 adsorbing material. Samples of three types of coal ash (fly ash, cyclone ashes and heavy ash) were collected at the Figueira-PR thermoelectric plant. The total time of the synthesis process by the two-step method was optimized. The following characteristics of the synthesis products were determined: mineralogical composition, chemical composition, morphology, functional groups and ion exchange capacity. The products synthesized presented a SiO2 / Al2O3 ratio of 1,2 and approximately 80% Na-A zeolite content. Zeolites were used as adsorbent material of CO2 having adsorption capacity between 492 and 655 mg / g. The higher adsorption capacity was obtained with the zeolite synthesized from the heavy ashes. The saturated zeolites were stable at room temperature and CO2 desorption occurred between 140-150 °C.

As indústrias lançam diversos poluentes no meio ambiente. Dentre os poluentes destacam-se os elementos tóxicos presentes em efluentes líquidos por acarretarem alto risco potencial à saúde humana e ao meio ambiente. Os efluentes podem ser tratados por materiais adsorventes, os quais podem ser provindos de resíduos industriais. Uma forma de contribuir significativamente na sustentabilidade de uma indústria é a transformação de um de seus resíduos em sub-produto de valor agregado para aplicação no tratamento de seus efluentes líquidos como adsorvente de baixo custo. O objetivo deste trabalho foi sintetizar, e caracterizar zeólitas de cinzas de carvão e avaliar sua aplicação como material adsorvente no tratamento de efluente. Os materiais zeolíticos derivados de três tipos diferentes de cinzas de carvão (cinzas manga, cinzas ciclone e cinzas pesadas) geradas na usina termelétrica de Figueira-PR foram usados para tratar o lixiviado do aterro de cinzas de carvão da mesma usina. As seguintes características das zeólitas foram determinadas: composição mineralógica, composição química, teor de carbono total, análise morfológica, área superficial específica, capacidade de troca catiônica (CTC), perda ao fogo, pH, condutividade e densidade aparente. A fase zeolítica formada foi do tipo sodalita com as três amostras usadas como matéria prima após ativação hidrotérmica alcalina. O material zeolítico de cinzas manga apresentou a menor relação SiO2/Al2O3 (1,46), maior CTC (2,36 meq g-1) e área superficial específica (69,5 m2 g-1) e, consequentemente, maior capacidade de remoção dos íons do efluente. As concentrações de As e Cr estavam acima do padrão de lançamento de efluentes. As três amostras de materiais zeolíticos apresentaram uma remoção significativa de Ni, Cd, Zn e Co na dose de 10 g.L-1. Os materiais zeolíticos das cinzas manga e ciclone foram eficientes para reduzir a concentração de As abaixo do limite imposto pela legislação, enquanto a remoção do Cr não foi efetiva com nenhum dos materiais. Na segunda etapa do trabalho, as zeólitas foram modificadas com o surfactante brometo de hexadeciltrimetilamônio (HTDMA-Br) em concentrações de 1,8 e 20 mmol L-1. A modificação das zeólitas não melhorou a eficiência de remoção do As. A remoção do Cr usando a amostra de zeólita de cinzas manga modificada com HDTMA-Br 20 mmol L-1 resultou em uma concentração final muito próxima ao limite permitido pela legislação. / The industries release various types of pollutants into to the environment. Among these pollutants are the liquid effluents containing toxic elements, they carry a high potential risk to human health and the environment. Some effluents can be treated by adsorbent materials, which can be made from industrial waste. One way to contribute significantly to the sustainability of an industry is to transform one of its residues into a value-added by-product and use in the treatment of its own liquid effluents as a low cost adsorbent. The objective of this estudy was to synthesize and characterize coal ash zeolites and evaluate their application as adsorbent material in the treatment of effluent. Zeolite materials derived from three different types of coal ash (fly ashes, cyclone ashes and heavy ashes) generated at the Figueira-PR thermoelectric plant were used to treat leachate from the coal ash landfill of the same plant. The following zeolite characteristics were determined: mineralogical composition, chemical composition, total carbon content, morphological analysis, specific surface area, cation exchange capacity (CTC), fire loss, pH, conductivity and bulk density. The zeolite phase formed with the three samples used as raw material after alkaline hydrothermal activation was sodalite. The zeolite material from fly ash had the lowest SiO2/Al2O3 ratio (1.46), higher CTC (2.36 meq g-1) and specific surface area (69.5 m2 g-1) and, consequently, greater effluent removal capacity. The As and Cr concentrations were above the effluent discharge standard. The three samples of zeolitic materials showed a significant removal of Ni, Cd, Zn and Co in the dose of 10 g L-1. The zeolite materials from fly and cyclone ash were efficient to reduce As concentrations below the limit imposed by legislation, while removal of Cr was not effective with any of the materials. In the second stage of the study, the zeolites were modified with the surfactant hexadecyltrimethylammonium bromide (HTDMA-Br) in concentrations of 1.8 and 20 mmol.L-1. The zeolite removal efficiency of As did not improve after its modification. Removal of Cr using the 20 mmol.L-1 modified HDTMA-Br modified fly ash zeolite sample resulted in a final concentration very close to the limit allowed by the legislation.

No presente estudo obteve-se com sucesso o compósito zeólita:magnetita usando-se como material de partida sulfato ferroso para síntese da magnetita e cinzas leves de carvão para síntese da fase zeolítica. A zeólita foi sintetizada por tratamento hidrotérmico alcalino e as nanopartículas de magnetita foram obtidas pela precipitação de íons Fe2+ em uma solução alcalina. Uma reprodutibilidade foi alcançada na preparação de diferentes amostras do nanocompósito zeolítico. O material foi caracterizado pelas técnicas de espectrometria de Infravermelho, difratometria de raios-X de pó, fluorescência de raios-X, microscopia eletrônica de varredura com a técnica de EDS, massa especifícia e área específica e por outras propriedades físico-químicas. O compósito era constituído pelas fases zeolíticas hidroxisodalita e NaP1, magnetita, quartzo e mulita das cinzas remanescentes do tratamento alcalino e magnetita incorporada na sua estrutura. A capacidade de remoção de U(VI) de soluções aquosas sobre o compósito zeólita:magnetita foi avaliada pela técnica descontínua. Os efeitos do tempo de contato e da concentração inicial do adsorbato sobre a adsorção foram avaliados. Determinou-se o tempo de equilíbrio do sistema e foram avaliados os modelos cinéticos de pseudo-primeira ordem, pseudo-segunda ordem e o modelo de difusão intrapartícula. Um tempo de contato de 120 min foi suficiente para a adsorção do íon uranilo alcançar o equilíbrio. A velocidade de adsorção seguiu o modelo cinético de pseudo-segunda-ordem, sendo que a difusão intrapartícula não era a etapa determinante do processo. Dois modelos de isotermas de adsorção, os modelos de Langmuir e de Freundlich, também foram avaliados. O modelo de Langmuir foi o que melhor se ajustou aos dados experimentais. A partir do modelo cinético e da isoterma que melhor descreveram o comportamento do sistema foi possível calcular os valores teóricos para a capacidade máxima de adsorção do U(VI) sobre o compósito zeólita:magnetita. As capacidades máximas de remoção calculadas foram de 20,7 mg.g-1 pela isoterma de Langmuir e de 23,4 mg.g-1 pelo modelo cinético de pseudo-segunda ordem. O valor experimental obtido foi 23,3 mg.g-1. / Within this work, a magnetic-zeolite composite was successfully synthesized using ferrous sulfate as raw material for the magnetic part of the composite, magnetite, and coal fly ash as raw material for the zeolitic phase. The synthesis of the zeolitic phase was made by alkali hydrothermal treatment and the magnetite nanoparticles were obtained through Fe2+ precipitation on alkali medium. The synthetic process was repeated many times and showed good reproducibility comparing the zeolitic nanocomposite from different batches. The final product was characterized using infrared spectroscopy, powder X-ray difraction, X-ray fluorescence, scanning electron microscopy with coupled EDS. Specific mass, specific surface area and other physicochemical proprieties. The main crystaline phases found in the final product were magnetite, zeolites types NaP1 and hydroxysodalite, quartz and mulite, those last two remaing from the raw materials. Uranium removal capacity of the magnetic zeolite composite was tested using bathc techniques. The effects of contact time and initial concentration of the adsorbate over the adsorption process were evaluated. Equilibrium time was resolved and the following kinectics and difusion models were evaluated: pseudo-first order kinectic model, pseudo-second order kinectic model and intraparticule difusion model. A contact time of 120 min turned out to be enough to reach equilibrium of the adsorption process. The rate of adsorption followed the pseudo-second order model and the intraparticle diffusion didnt turned out to be a speed determinant step. Two adsorption isotherms models, the Langmuir model and the Freundlich model, were also evaluated. The Langmuir model was the best fit for the obtained experimental data. Using the best fitted adsorption isotherm and kinectic model, the theorical maximum adsorption capacity of uranium over the composite was determined for both models. The maximum removal capacity calculated was 20.7 mg.g-1 for the Langmuir isotherm and 23.4 mg.g-1 for the pseudo-second order model. The experimental value attained was 23,3 mg.g-1.

Os depósitos de caulim apresentam-se amplamente distribuídos no planeta, e das reservas brasileiras classificadas como medidas e indicadas, 97% encontram-se na região norte do país onde estão localizadas as principais empresas produtoras de caulim destinado à indústria de papéis. Ocorre que durante as etapas de processamento do minério são gerados grandes volumes de rejeito constituído predominantemente por caulinita, um dos argilominerais mais utilizados como matéria-prima em síntese de zeólitas. Neste trabalho, materiais zeolíticos foram sintetizados utilizando como fonte principal de silício e alumínio um rejeito industrial gerado durante o beneficiamento do caulim para cobertura de papel; o material de partida e as fases formadas como produtos de reação foram caracterizados por difração de raios X, microscopia eletrônica de varredura, espectroscopia de refletância difusa no infravermelho com transformada de Fourier, análise térmica e área superficial específica pelo método BET; sendo posteriormente avaliados quanto à capacidade de adsorção por azul de metileno em sistema descontínuo. O processo de síntese ocorreu em condições hidrotermais através de autoclavagem estática e os efeitos tempo-temperatura, assim como também as relações Si/Al e Na/Al foram considerados. Os resultados mostram que na metodologia desenvolvida com o rejeito de caulim, inicialmente calcinado a 700°C por 2 horas, submetido em seguida à reação em meio alcalino a 90ºC por 48 horas na presença de uma fonte adicional de sílica foi obtida zeólita do tipo faujasita com boa cristalinidade como fase predominante no produto de síntese. Os dados dos ensaios de adsorção determinados por espectrofotometria UV-visível e ajustados pelos modelos de Langmuir e Freundlich sugerem que o material faujasítico apresenta boa capacidade adsortiva atingindo eficiências entre 85 e 92% para concentrações na faixa de 10 a 30 mg/L, demonstrando assim, ser o referido material uma alternativa eficiente e de baixo custo quando utilizado para a remoção de corantes de solução aquosa no tratamento de efluentes industriais. / Kaolin deposits have become widely distributed on the planet, Brazilian\'s reserves classified as measured and indicated, 97% are in the northern region where are located the main producers of kaolin for the paper industry. During the processing steps of the ore are generated large amount of waste constituted predominantly by kaolinite, one of the most widely used clayminerals as a raw material in synthesis of zeolites. In the present work, zeolitic materials were synthesized using as main source of silicon and aluminum an industrial waste generated during the processing of kaolin for paper coating, the starting material and formed phases as reaction products were characterized by X-ray diffraction, scanning electron microscopy, diffuse reflectance spectroscopy in the infrared Fourier transform, thermal analysis and specific surface area by BET method; and subsequently evaluated for adsorption capacity for methylene blue in a batch system. The synthesis process occurred in hydrothermal conditions and the effects, time-temperature, as well as the relations Si/Al and Na/Al were considered. The results show that in the methodology developed from kaolin waste, initially calcined at 700°C for 2 h, subjected then reaction in alkaline medium at 90°C for 48 h in presence of additional silica was obtained faujasite-type zeolite with good crystallinity as phase predominant in the synthesis product. Adsorption data determined by UV-visible spectrophotometry were fitted using Langmuir and Freundlich isotherms models and suggest that the zeolitic material has good adsorptive capacity, achieving efficiencies between 85 and 92% at concentrations in the range 10 30 mg/L, thus becoming, this material, an effective and low-cost alternative when used for the removal of dyes from aqueous solution in the treatment of industrial effluents.