RESUMO Membranas podem ser consideradas películas poliméricas ou inorgânicas que funcionam como uma barreira semipermeável para uma filtração em escala molecular, separando duas fases e restringindo, total ou parcialmente, o transporte de uma ou várias espécies químicas (solutos) presentes na solução. Portanto, o objetivo deste trabalho é produzir membranas de poliétersulfona (PES) e poliétersulfona / argila pela técnica de inversão de fase e avaliar a presença de argila na obtenção de membranas para o tratamento de efluentes líquidos. O solvente utilizado foi a dimetilformamida (DMF) e argilas utilizadas foram Brasgel PA (MMT) e Cloisite Na (CL Na) nas proporções de 3 a 5% (em peso). Por difração de raios-X (DRX), as membranas com 3% das argilas MMT e CL Na aparentemente apresentaram estruturas parcialmente esfoliadas; para a composição com 5% de CL Na observou-se um pequeno pico, que indica que esta é, possivelmente, uma estrutura intercalada ou microcompósito. A partir dos resultados de microscopia eletrônica de varredura (MEV), visualizou-se que a superfície da membrana de PES puro apresentou uma estrutura aparentemente sem poros, no aumento utilizado e, uma superfície sem rugosidade quando comparada com às membranas com argila. As medidas de ângulo de contato indicaram que a inclusão da argila alterou a capacidade de molhamento das membranas. O fluxo com água destilada para todas as membranas iniciou alto e ao longo do tempo chegou a um patamar de estabilização. Assim, pôde-se concluir que a presença e o teor de argila alteraram a morfologia da membrana, contribuindo para um aumento do fluxo de água.

ABSTRACT Membranes can be considered polymeric or inorganic films that function as a semipermeable barrier to filtration on a molecular scale, separating two phases and restricting, totally or partially, the transportation of one or more chemical species (solute) present in the solution. Therefore, the aim of this work is to produce polyethersulfone membranes (PES) and polyethersulfone/clay by phase inversion technique and evaluate the presence of clay in obtaining membranes for wastewater treatment. The used solvent was dimethylformamide (DMF) and clays were Brasgel PA (MMT) and Cloisite Na (CL Na) in the proportion of 3 to 5% (wt.). By X-ray diffraction (XRD), the membranes with 3% of MMT and CL Na clays apparently had partially exfoliated structures. For the composition with 5% of CL Na a small peak was observed, which indicates that this is possibly an intercalated structure or microcomposite. By scanning electron microscopy (SEM), visualizes that the pure suface of the pure PES membrane a structure apparently without pores was observed in the used magnification and without roughness surface when compared to membranes with clay. The measurements of contact angle indicated that the inclusion of clay altered the wetting ability of the membranes. The flow with distilled water for all membranes started high and over time reached a stabilization level. Thus, it can be concluded that the presence and the content of clay altered the morphology of the membrane, contributing to an increase in water flow.

This work evaluated the catalytic activity of TiO2 synthesized by the Pechini method. with varying molar ratios of 2:1, 3:1 and 4:1 of citric acid/metallic cations, in the photocatalytic degradation of methyl red dye in aqueous solution. The samples were characterized by X-ray diffraction, phase quantification by Rietveld structure refinement, and textural analysis by nitrogen adsorption, and their photocatalytic performance was bench- tested. The results indicated that the 3:1 and 4:1 samples contained two phases, with 84.4 and 89% of anatase phase and 15.6 and 11% of rutile phase, respectively. The 2:1 sample contained only anatase phase. The total discoloration of methyl red dye in 24 hours confirmed the high photocatalytic efficiency of the 2:1 sample, which was ascribed to the formation of monophasic anatase.

Recent interest in polymer/organoclays nanocomposites systems is motivated by the possibility of achieving enhanced properties and added functionality at lower clay loading as compared to conventional micron size fillers. By adding montmorillonite clay to polyamide 6 increases the Young modulus, yield strength and also improves barrier properties. In this work, nanocomposites of polyamide 6 with montmorillonite clay were obtained. The clay was chemically modified with three different quaternary ammonium salts such as: Dodigen, Genamin and Cetremide. In this case, a dispersion of Na-MMT was stirred and a salt equivalent to 1:1 of cation exchange capacity (CEC) of Na-MMT was added to the dispersion. The montmorillonite clay (untreated and treated by ammonium salts) and nanocomposites were characterized by X ray diffractions. Also the nanocomposites were characterized by transmission electron microscopy and mechanical properties. The results indicated that all the quaternary ammonium salts were intercalated between the layers of clay, leading to an expansion of the interlayer spacing. The obtained nanocomposites showed better mechanical properties when compared to polyamide 6. The clay acted as reinforcing filler, increasing the rigidity of nanocomposites and decreasing its ductility.