The aim of this study was to improve the mechanical properties &ldquo / Moplen&rdquo / EP300L which is a heterophase copolymer. Polymer blends and nanocomposites were prepared by melt compounding method in a twin screw extruder. Nanofil&reg / 5 (N5) and Nanofil&reg / 8(N8) were used as the organoclays, and maleic anhydride grafted polypropylene (M) was used as the compatibilizer. The effects of additive concentrations and types of organoclays on the morphology, mechanical and thermal properties were investigated. Organoclay loading over 2 wt% prevented the intercalation mechanism resulting in large aggregates of clay, thus the material properties became poor even in the presence of compatibilizer. Compatibilizer addition improved the intercalation ability of the polymer, however a substantial increase in mechanical properties was not obtained up to 6 wt % loading of the compatibilizer. XRD analysis revealed that intercalated structures were formed with the addition of compatibilizer and organoclay. The nanocomposites that were prepared with N5 type organoclay showed delaminated structures at 6 wt % compatibilizer loading. v Nanofill &reg / 5 exhibited the highest improvements in mechanical properties, since the degree of organoclay dispersion was better in Nanofill &reg / 5 containing nanocomposites in comparison to Nanofill &reg / 8 containing ones. The DSC analysis indicated a insignificant reduction in the melting temperature of the ternary nanocomposites.

Adsorption kinetics and adsorption-desorption of atrazine on organoclay composites prepared with the surfactant 6-piperazin-1-yl-N,N'-bis-(1,1,3,3-tetramethyl-butyl)-(1,3,5)triazine-2,4-diamine and Houston Black clay were studied using the indirect batch equilibration procedure. The organoclay composites sorbed significantly more atrazine than the Houston Black clay. Adsorption equilibrium was reached after 72 h for the organoclay composites. Atrazine adsorption isotherms were described by linear partitioning. The Koc values ranged from 605 to 5271 L kg-1 for the organoclay composites compared to a value of 41 L kg-1 for the Houston Black clay. The organoclay composite containing 20% surfactant on a total weight basis provided the most efficient adsorption of atrazine, although organoclay composites containing much lower amounts of surfactant also adsorbed significant amounts of atrazine. An average of 11% of sorbed atrazine was released during desorption. Characterization of desorption products showed only atrazine molecules being released from the organoclay composites.

Substantial environmental contamination has occurred from coal tar creosote and pentachlorophenol (C5P) in wood preserving solutions. The present studies focused on the characterization and remediation of these contaminants. The first objective was to delineate a sequence of biological changes caused by chlorinated phenol (CP) exposure. In Clone 9 cells, short-term exposure to 10 ?M C5P decreased pH, GJIC, and GSH, and increased ROS generation. Long-term exposure caused mitochondrial membrane depolarization (25 ?M), increased intracellular Ca2+ (50 ?M), and plasma membrane depolarization (100 ?M). Cells were affected similarly by C5P or 2,3,4,5-C4P, and similarly by 2,3,5-C3P or 3,5-C2P. Endpoints were affected by dose, time, and the number of chlorine substituents on specific congeners. Thus, this information may be used to identify and quantify unknown CPs in a mixture to be remediated. Due to the toxic effects observed due to CP exposure in vitro, the objective of the second study was to develop multi-functional sorbents to remediate CPs and other components of wood preserving waste from groundwater. Cetylpyridinium-exchanged low pH montmorillonite clay (CP-LPHM) was bonded to either sand (CP-LPHM/sand) or granular activated carbon (CP-LPHM/GAC). Laboratory studies utilizing aqueous solution derived from wood preserving waste indicated that 3:2 CP-LPHM/GAC and CP-LPHM/sand were the most effective formulations. In situ elution of oil-water separator effluent indicated that both organoclay-containing composites have a high capacity for contaminants identified in wood preserving waste, in particular high molecular weight and carcinogenic PAHs. Further, GAC did not add substantial sorptive capacity to the composite formulation. Following water remediation, the final aim of this work was to explore the safety of the parent clay minerals as potential enterosorbents for contaminants ingested in water and food. Calcium montmorillonite and sodium montmorillonite clays were added to the balanced diet of Sprague-Dawley rats throughout pregnancy. Based on evaluations of toxicity and neutron activation analysis of tissues, no significant differences were observed between animals receiving clay supplements and control animals, with the exception of slightly decreased brain Rb in animals ingesting clay. Overall, the results suggest that neither clay mineral, at relatively high dietary concentrations, influences mineral uptake or utilization in the pregnant rat.

Neste trabalho, materiais nanocompósitos de poli(imida) (PI) derivada de BTDA-pFDA-Mel e argila do tipo montmorilonita, organicamente modificada (O-MMT), foram sintetizados usando a metodologia de two-steps. O componente inorgânico do nanocompósito foi adicionado nas concentrações de 3,3, 5,3 e 8,3% em massa. As membranas sintetizadas foram caracterizadas por Espectroscopia de Absorção na Região do Infravermelho com Transformada de Fourrier (FTIR), Difração de Raio X (DRX), Termogravimetria (TG), Espectroscopia de Fotoelétrons Excitados por Raio X (XPS) e Microscopias Ótica (MO), Eletrônica de Varredura (MEV) e de Transmissão (MET). Os resultados comprovam a formação de PI e uma estrutura de nanocompósito do tipo intercalado, onde a cadeia polimérica expulsa o surfactante do espaço interlamelar; além de apresentar estruturas de argila parcialmente esfoliadas. Os materiais sintetizados foram avaliados como polieletrólito em célula a combustível alcalina (Alkaline Fuel Cell - AFC), obtendo condutividades iônicas em torno de 0,032 S cm-1 e de 0,017 S cm-1 para as membranas de PI pura e de nanocompósito com 3,3% de argila em massa, respectivamente, ambas a 60 °C, as quais são na ordem ou até mesmo superior que os polieletrólitos comercias (Tokuyama®, 0,014 S cm-1) para eletrólito alcalino. Apesar de condutividades razoáveis, a performance obtida para as AFCs em operação não foram satisfatórias, desta forma, membranas de nanocompósitos com PI de cadeia principal de maior mobilidade foram sintetizadas, caracterizadas e avaliadas nas AFCs. Ademais, neste segundo nanocompósito, a adição de grupamentos amino na cadeia principal foram realizados para aumentar a condutividade iônica. Assim, este segundo material apresentou uma maior performance nas AFCs quando comparado com o nanocompósito de PI de cadeia mais rígida e com a membrana comercial Tokuyama® nas mesmas condições. Além disso, a carbonização superficial das amostras foi realizada por meio de tratamento térmico. A formação de estruturas grafitizadas nos materiais de PI pura e dos nanocompósitos foram investigadas por FTIR, DRX, TG, XPS e EPR. Foi encontrado que a formação de estruturas do tipo grafite nas amostras ocorrem principalmente nas primeiras camadas (grafitização superficial), preservando a estrutura interna da poli(imida). Com isso, estruturas poliméricas ou nanocompósitos com superfícies grafitizadas podem atuar tanto como polieletrólitos e ser um caminho promissor para o desenvolvimento de arranjos eletrodo-membrana (Membrane Electrode Assembly - MEA) mais eficientes para células a combustíveis alcalinas, como em processos de catálise heterogênea e processos de separação com membranas. / In this work, Poli(imide)/clay (PI/clay) nanocomposite membranes were synthesized by employing a two-steps method using organically modified montmorillonite clay (O-MMT) with different amounts of O-MMT loading (3.3, 5.3 and 8.3 wt.%). Fourier transform infrared spectroscopy (FTIR), X-ray power diffraction (XRD), thermogravimetric analysis (TG), X-ray photoelectron spectroscopy (XPS), optical microscopy (OM), scanning electron microscope (SEM) and transmission electron microscopy (TEM) measurements, confirmed the formation of pure PI and intercalated-nanocomposite structures. The results revealed parallel clay layers with interlamellar PI and some organoclay partially exfoliated. In addition, the polyelectrolyte membranes of PI and PI/O-MMT (3.3 wt.%) showed that the ionic conductivity were 2- and 1-fold, respectively, higher than that of commercial membrane (Tokuyama®, 0.014 S cm-1), in alkaline fuel cells (AFC) at 60 °C. Despite the fact that the membranes of pure PI and PI/O-MMT demonstrated a good degree of ionic conductivity, rapid fuel cell performance deactivation occurred for the temperature higher than 75 °C. Furthermore, the lack of prepared polyelectrolyte ionic groups, led us to consider alternative synthesis of PI/clay nanocomposite membranes. Thus, the performance for second polyelectrolyte was superior when compared to pure PI, PI/O-MMT and commercial Tokuyama® membranes at same conditions. Moreover, the samples were also surface carbonized by thermal treatment. Combining FTIR, XRD, TG, XPS and electron paramagnetic resonance (ESR) analysis, the results suggested that graphitized nanostructures formation occurred mainly on the surface, maintaining the PI bulk structure. Therefore, graphitized PI/clay membranes may act as one promising way for enhancing both membrane electrode assembly in alkaline fuel cells and gas separation or catalysis.

Submitted by Caroline Falcao (caroline.rfalcao@ufpe.br) on 2017-06-07T16:52:00Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) 2011-Tese-MarildaCarvalho.pdf: 2363493 bytes, checksum: 73792c6b5b73cd77692479b820749baf (MD5) / Made available in DSpace on 2017-06-07T16:52:00Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) 2011-Tese-MarildaCarvalho.pdf: 2363493 bytes, checksum: 73792c6b5b73cd77692479b820749baf (MD5) Previous issue date: 2011-02-17 / A contaminação da água por compostos orgânicos tóxicos é uma dasmaiores preocupações ambientais e tem aumentado o interesse na busca de adsorventes eficientes para a remoção desses compostos. A adsorção utilizando argilas constitui uma das tecnologias de aplicação crescentes empregadas no tratamento secundário de efluentes contaminados por compostos orgânicos de origem na indústria de petróleo. Este trabalho investigou um processo de adsorção dos compostos orgânicos benzeno, tolueno, etilbenzeno, xilenos (BTEX) e do fenol presentes em soluções aquosas em baixas concentrações, até 20 mg/L, por meio de uma argila esmectítica (chocolate) de origem do estado da Paraíba, no nordeste do Brasil, visando colaborar com tecnologias de caráter sustentável, para a indústria de petróleo e petroquímica. A argila organofílica foi sintetizada a partir do sal quaternário (SQA) cloreto de hexadeciltrimetilamônio na concentração de 150% da capacidade de troca catiônica (CTC) da argila, a qual promoveu o aumento do espaçamento basal da estrutura cristalina do argilomineral de 14,73 Å para 22,08 Å. Procedeu-se à avaliação de sistemas de adsorção multicomponente, em regime descontínuo, considerando as abordagens cinéticas e de equilíbrios. Os teores dos componentes BTEX e fenol foram quantificados por cromatografia líquida de alta eficiência (CLAE). Os resultados experimentais ajustaram-se bem ao modelo de equilíbrio combinado de Langmuir-Freundlich e revelaram capacidades máximas de adsorção entre 1,27mg/g (tolueno) a 8,28mg/g (fenol) e cinéticas de equilíbrio em torno de 30 minutos. Parâmetros relacionados à heterogeneidade superficial da argila indicaram a existência de sítios ativos específicos. As afinidades de adsorção de BTEX e de fenol pela argila organofílica no sistema multicomponente apresentaram-se na ordem decrescente: etilbenzeno > xilenos > tolueno > fenol > benzeno. Estas afinidades estiveram relacionadas ao tamanho das moléculas dos aromáticos. As eficiências de remoção obtidas variaram em torno de 55% e 90%. / Water contamination by toxic organic compounds is a major environmental concern and has increased the interest in finding efficient adsorbents for the removal of these compounds. The adsorption using clay has become one of the technologiesincreasingly employed in secondary treatment of effluents contaminated by organic compounds in the oil industry. This study investigated the process of adsorption of organic compounds benzene, toluene, ethylbenzene, xylenes (BTEX) and phenol existing in aqueous solutions at low concentrations, up to 20 mg/L, by means of a smectite clay (chocolate)'s home state of Paraiba in northeastern Brazil, aiming to collaborate with nature sustainable technologies for the petroleum and petrochemical industry. The organoclay was synthesized from the quaternary ammonium salt (SQA) hexadecyltrimethylammonium chloride at a concentration of 150% of the cation exchange capacity (CEC) of clay, which promoted the increase in basal spacing of 4.73 Å clay to 22.08 Å. The evaluation of the multicomponent adsorption systems was made through discontinuous system, considering the kinetic and equilibrium approaches. The concentration of BTEX and phenol components was quantified by high performance liquid chromatography (HPLC). The experimental results fit well to the combined equilibrium model of Langmuir-Freundlich and showed maximum adsorption capacities ranging from 1.27 mg/g (toluene) to 8.28 mg/g (phenol) and kinetic equilibrium in about 30 minutes. Parameters related to the heterogeneity of the clay surface indicated the existence of specific active sites. The adsorption affinity of BTEX and phenol in the organoclay in the multicomponent system is presented in descending order: ethylbenzene>xylenes>toluene>phenol>benzene. These affinities were related to the size of the aromatic molecules. The removal efficiencies obtained ranged around 55% and 90%.

Sais quaternários de amônio são amplamente usados como agentes antissépticos, desinfetantes, detergentes e preservantes. Além disso, sais quaternários de amônio são frequentemente utilizados como algicidas, sendo o cloreto de dodecil dimetil benzil amônio (Cloreto de benzalcônio) o mais efetivo contra estes microorganismos. No entanto sua aplicação como algicida de superfícies é limitada, devido a sua alta hidrofilicidade, ocasionando uma alta lixiviação deste composto quando a superfície é exposta à alta umidade e intempéries de clima tropical. Atualmente compostos como Diuron e S-Triazina são empregados como algicidas, considerados de baixa lixiviação. No entanto, altos níveis de concentração destes biocidas foram detectados em regiões costeiras evidenciando a lixiviação destes biocidas, quando utilizados em tintas para casco de navio. Assim surge a necessidade do desenvolvimento de um algicida para suprir as deficiências de lixiviação dos compostos empregados atualmente. Materiais como as argilas organofílicas são uma excelente alternativa, pois são altamente hidrofóbicas. Portanto sintetizou-se neste trabalho uma argila organofílica utilizando-se cloreto de benzalcônio, a qual foi utilizada em uma formulação de tinta imobiliária. O material foi caracterizado pelas técnicas de difração de Raios X e análise termogravimétrica. Um filme de tinta foi submetido a uma câmara de lixiviação, simulando a ação da chuva. Após a lixiviação o filme de tinta seguiu para testes microbiológicos, para verificar se a superfície ainda possui proteção microbiana. As algas testadas foram das espécies Phormidium cebenense, Trentepohlia odorata, Chlorella sp e Scenedesmus quadricauda colocadas num pool de algas. Através das análises de Difração de Raios X e termogravimétrica é possível determinar a estrutura e quantificar o teor cloreto de benzalcônio no material, respectivamente. Os testes microbiológicos e de lixiviação avaliaram a capacidade biocida assim como a resistência à intempérie do material. O novo composto sintetizado neste trabalho apresentou um alto potencial para uso como agente microbiano em tintas. / Quaternary ammonium compounds are widely used as antiseptic agents, disinfectants, detergents and preservatives. In addition, quaternary ammonium compounds are often used as algaecides, and dodecyl dimethyl benzyl ammonium chloride (benzalkonium chloride) is the most effective against these microorganisms. However benzalkonium chloride is not used as surface algaecide compound due its high hydrophilic, bring on high leaching of this compound when the surface is exposed to high humidity and severe weather from tropical climate. Currently, compounds such as diuron and s-triazine are used as microbial agent, considered low leaching. However diuron and s-triazine were detected in coastal regions in high levels concentration showing the leaching of these biocides when used in antifouling paints in ships. Considering these, it can be observed the necessity to develop a new algaecide to overcome the failings of leaching of the compounds used nowadays. Material as organoclay is an excellent alternative because they are highly hydrophobic. Therefore in this work was synthesized a new nanomaterial using benzalkonium chloride, which was applied in a house paint formulation. The material was characterized by the techniques of X-ray diffraction and thermogravimetric analysis. A film coating was placed in a leaching chamber, simulating the action of rain. After leaching the coating film was applied to microbiological tests to check if the surface still had microbial protection against the following algae species: Phormidium cebenense, Trentepohlia odorata, Chlorella sp and Scenedesmus quadricauda; placed in a pool of algae. It was possible to determine the structure and quantify the amount of benzalkonium chloride in the material through X-ray Diffraction and Thermogravimetric analysis, respectively. The biocide capabilities as well as the resistance to weathering of coating with the material were analyzed by microbiological and leaching test, respectively. The new compound developed in this study has a high potential to be used as microbial agent in paints.

Neste trabalho foram investigados a obtenção de argilas organofílicas e nanocompósitos de Poliestireno com estas argilas. A primeira parte deste trabalho teve como objetivo a modificação de argilas esmectíticas naturais brasileiras, tornando-as organofílicas e adequadas à aplicação em nanocompósitos de matriz poliméricas. Para modificação foram utilizados sais quaternários e foi avaliado quais parâmetros do processo de obtenção mais influenciam nas propriedades das argilas organofílicas. Para tanto foi utilizada a argila Brasgel (fornecida pela BUN, e naturalmente cálcica), e foram propostos diferentes métodos de preparo de argilas, onde quatro parâmetros foram avaliados: os sais quaternários amônio; a granulometria da argila (#400 e coloidal), a temperatura de processamento (ambiente e a 70oC) e os tempos utilizados durante o processo de incorporação dos sais quaternários na estrutura dos materiais argilosos. Os materiais obtidos foram caracterizados por difração de raios-X (DRX), ensaios de inchamento de Foster e analise térmica diferencial (DTA). Obteve-se incremento do espaçamento basal com todas as argilas utilizadas. Mostrou-se que os dois principais parâmetros determinantes na incorporação das argilas são o tempo de mistura e a temperatura (de 70oC) empregada. A segunda parte do trabalho teve como objetivo obter nanocompósitos de PS com argilas organofílicas (sendo uma argila obtida na primeira parte e uma comercial, Cloisite 20A) via intercalação no polímero fundido. Os nanocompósitos foram preparados em extrusora de rosca dupla e em misturador interno. As argilas foram adicionadas ao polímero fundido na forma de um pó e em suspensão de etanol. Os nanocompósitos obtidos foram moldados por compressão e injeção (com variações nas condições de injeção para avaliar a influencia na estrutura final), para realização da caracterização. A principal técnica de caracterização utilizada foi a caracterização reológica com ensaios de cisalhamento de pequenas amplitudes (COPA) e de varredura de tempo. Os materiais foram caracterizados também por técnicas auxiliares como DRX, microscopia eletrônica de transmissão (MET), analises térmicas diferenciais (DTA) e ensaios mecânicos. Obteve-se nanocompósitos de estrutura intercalada. Os materiais obtidos no misturadores mostraram as melhores dispersões de argila. . Verificou-se que o tempo de residência dos materiais é um dos fatores mais importantes na obtenção dos nanocompósitos. Os ensaios mecânicos não mostraram alteração significativa. / In this work, the obtention of organoclays and nanocomposites of polystyrene (PS) using these modified clays was studied. In a first part Brazilian smectites clays were modified to be used in clay containing polymer nanocomposites. Several quaternary ammonium salts and experimental methods to modify the clays were used. In particular four parameters were evaluated: the type of ammonium salt, the particle clay size, the temperature and time used during the process of modification. The samples obtained were characterized by X-ray diffraction (XRD), Foster swelling test and differential thermal analysis (DTG). The results indicated that the most two important parameters in the process of modification are the time and the temperature used. In a second part nanocomposites of PS with organoclays (one obtained in the first part, and commercial clay, named cloisite 20A) were obtained by melt intercalation method using a twin screw extruder and an internal mixer. The clays were incorporated to the polymer as a fine dried powder and as a suspension of ethanol. Nanocomposites were molded by compression and injection. The injection conditions were modified to evaluate their influence on the morphology of the samples. The nanocomposites samples were characterized by XRD, transmission electronic microscopy (TEM), DTG and mechanical tests. Small amplitude oscillatory shear (SAOS) and time sweep tests were carried out. Nanocomposites of intercalated structure were obtained. The ones obtained using the internal mixer were shown to present a finer microstructure. The experimental results revealed that the residence time was showed the most important parameter in obtention of nanocomposites.

Orientadores: Meuris Gurgel Carlos da Silva, Onelia Aparecida Andreo dos Santos / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-24T22:59:54Z (GMT). No. of bitstreams: 1 Bedin_Sidmara_M.pdf: 4205652 bytes, checksum: d622e46268c9acb2352410201461233c (MD5) Previous issue date: 2014 / Resumo: Diariamente, uma grande quantidade de fluxos de água sofre contaminação por compostos orgânicos como, por exemplo, o benzeno, tolueno e xileno (BTX), os quais são compostos tóxicos e nocivos ao meio ambiente e aos seres humanos. Sendo assim, o estudo de técnicas de remoção e tratamento desses poluentes vem se tornando tema de muitas pesquisas. A adsorção tem se mostrado uma técnica bastante eficiente, pois atende aos limites da legislação, apresenta baixo consumo energético e custo de processo, ainda mais quando se faz uso de um adsorvente alternativo, como é o caso da argila organofílica. Nesse trabalho foi proposto avaliar a argila esmectítica sódica nacional Fluidgel, na forma natural e organofilizada, como materiais adsorventes alternativos na remoção dos compostos orgânicos BTX de soluções aquosas, em ensaios em sistema batelada e em sistema dinâmico. A argila organofílica foi preparada a partir da argila comercial e do sal quaternário de amônia HDTMA e se verificou a capacidade de troca catiônicas dos adsorventes. Foram realizadas técnicas de caracterização com a finalidade de determinar a área superficial do material, estrutura de poros, estrutura cristalina, morfologia de superfície, composição química, perda de massa e água e identificação de grupos funcionais de superfície. Testes preliminares comprovaram o caráter hidrofóbico da argila organofílica e sua afinidade por compostos orgânicos, bem como o caráter hidrofílico da argila comercial. Ensaios cinéticos de pH mostraram que o mesmo não afeta de maneira significativa o processo de adsorção. Os ensaios cinéticos de adsorção realizados em sistema batelada alcançaram o equilíbrio em 3h e apresentaram porcentagens de remoção de poluente superiores a 90%, com concentração inicial de 1,09 mmol/L. Os modelos cinéticos analisados foram o de pseudoprimeira ordem, pseudossegunda ordem e o de difusão intrapartícula, sendo que o modelo de pseudossegunda ordem melhor descreveu os dados experimentais. Para as isotermas de equilíbrios, testou-se as temperaturas de 35, 25 e 15 oC, sendo a maior capacidade de remoção com a maior temperatura, indicando que a adsorção nesse caso é de natureza endotérmica. Os modelos de isotermas avaliados foram Langmuir, Freundlich, Sips, DSL, MSAM e D-R, porém apenas o modelo de D-R descreveu de maneira satisfatória os dados experimentais. Pela análise dos parâmetros termodinâmicos, verificou-se que o processo de adsorção em estudo é espontâneo, favorecido a altas temperaturas e que possivelmente ocorre fisissorção. Devido à alta volatilidade dos compostos BTX, foi feita uma adaptação na adsorção em sistema dinâmico através de coluna de leito fixo e se realizou um ensaio cinético em leito de adsorção. A ordem de remoção dos compostos orgânicos, para ambas as argilas, foi xileno > tolueno > benzeno / Abstract: Daily a large amount of water flows suffers contamination by organic compounds as, for example, benzene, toluene and xylene (BTX), which are toxic compounds and harmful to the environment and to humans. Thus, the study of techniques for removal and treatment of these pollutants has become the subject of much research. The adsorption has proven to be a very effective technique because it meets the limits of the law, has low energy consumption and process cost, further when it makes use of an alternative adsorbent, as is the case with organoclay. In this study, it was proposed evaluate the national sodium smectite clay Fluidgel , in the natural and organophilizated form, as an alternative adsorbent material to the removal of organic compounds BTX from aqueous solutions in batch and dynamic system essays. The organoclay was prepared from the commercial clay and the quaternary ammonium salt HDTMA and it was verified the cationic exchange capacity of the adsorbents. Were performed characterization techniques in order to determine the surface area of the material, pore structure, crystal structure, surface morphology, chemical composition, mass and water loss and identification of surface functional groups. Preliminary tests confirmed the hydrophobic character of the organoclay and their affinity for organic compounds and the hydrophilic character of the commercial clay. pH kinetic experiments showed that the same does not affect significantly the adsorption process. Kinetic assays of adsorption performed in batch system reached equilibrium in 3 hours and showed pollutant removal percentages greater than 90%, with an initial concentration of 1.09 mmol/L. The kinetic models analyzed were the pseudo first order, pseudo second order and the intraparticle diffusion, being that the pseudo second order model best described the experimental data. For the equilibrium isotherm, was tested at temperatures of 35, 25 and 15 °C, being the largest removal capacity with the greatest temperature, indicating that the adsorption of this case is endothermic in nature. The isotherm models evaluated were Langmuir, Freundlich, Sips, DSL, MSAM and D-R, but only the D-R model described satisfactorily the experimental data. By the analysis of the thermodynamic parameters, it was found that the adsorption in study is spontaneous and favorable at high temperatures and that possibly occurs physisorption. Due to the high volatility of BTX compounds, it was made an adaptation to dynamic adsorption system through fixed bed column and a kinetic assay was carried out in adsorption bed. The order of removal of organic compounds for both clays was xylene > toluene > benzene / Mestrado / Engenharia Química / Mestra em Engenharia Química

The objective of this work was the development of an efficient adsorbent for irreversible immobilization of heavy metals in contaminated soils. The adsorbent was prepared by pillaring of montmorillonite with silica followed by grafting of a chelate ligand on its surface. Obtained adsorbent was mesoporous with high content of adsorption sites. Its structure was studied by BET adsorption of N2, dynamic light scattering, and scanning electron microscopy. The adsorption capacity of the organoclay was measured by its mixing with contaminated kaolin and soil samples and by analysis of heavy metal contents in leachate. Deionized water and 50% acetic acid were used for leaching of metals from the samples. As it was demonstrated by the experiments, the adsorbent was efficient in immobilization of heavy metals not only in neutral aqueous media but also in the presence of weak acid. As a result, the adsorbent can be used for reduction of heavy metal leaching from contaminated sites.

The objective of this work was the development of an efficient adsorbent for irreversible immobilization of heavy metals in contaminated soils. The adsorbent was prepared by pillaring of montmorillonite with silica followed by grafting of a chelate ligand on its surface. Obtained adsorbent was mesoporous with high content of adsorption sites. Its structure was studied by BET adsorption of N2, dynamic light scattering, and scanning electron microscopy. The adsorption capacity of the organoclay was measured by its mixing with contaminated kaolin and soil samples and by analysis of heavy metal contents in leachate. Deionized water and 50% acetic acid were used for leaching of metals from the samples. As it was demonstrated by the experiments, the adsorbent was efficient in immobilization of heavy metals not only in neutral aqueous media but also in the presence of weak acid. As a result, the adsorbent can be used for reduction of heavy metal leaching from contaminated sites.