This work evaluated the use of corncob as a support for the immobilization of an extracellular fructosyltransferase (E.C. 2.4.1.9) from Aspergillus oryzae IPT-301, aiming at the synthesis of a stable biocatalyst for the production of fructooligosaccharides. The transfructosylation activity of the immobilized enzyme was maximized via experimental design. Additionally, the biochemical properties and stability of the immobilized enzyme, as well as the reaction kinetics, were determined. The enzyme immobilized on alkali-treated corncob showed the highest transfructosylation activity at 50 °C and pH 5.5. It also presented a wide pH stability and a half-life around 1.4 times greater than the soluble enzyme. Furthermore, the immobilized enzyme showed 53% of retention of catalytic activity in a second consecutive reaction cycle, showing the potential for reuse. These results suggest that alkali-treated corncob is a promising support material for the synthesis of heterogeneous biocatalysts aiming at fructooligosaccharide production, which can contribute to the valorization of this abundant agro-waste. E.C. EC E C (E.C 2.4.1.9 2419 2 4 1 9 IPT301, IPT301 IPT 301, 301 IPT-301 fructooligosaccharides design Additionally kinetics determined alkalitreated alkali treated 5 55 5.5 halflife half life 14 1. Furthermore 53 cycle reuse agrowaste. agrowaste agro waste. waste agro-waste E.C 2.4.1. 241 IPT30 30 IPT-30 5. 2.4.1 24 IPT3 3 IPT-3 2.4. IPT- 2.4 2.

Abstract The process of beneficiation of a peaty ceramic raw material extracted from the Poços de Caldas region, MG, through the composting method to reduce organic matter (OM) was analyzed. The raw materials used in separate piles were divided, keeping one of the samples pure (TP) and adding bovine wastes in the second (TB). The process lasted 6 months and, at the end of each month, the amount of MO was analyzed by the Walkley-Black method. Results of maximum degradation of 56%±6% of OM in the TB and 47%±5% of OM in the TP were obtained. The ceramic characterization of the processed raw material was then carried out. It has been proved that the proposed method is efficient for the decrease of OM in the ceramic raw material. Regarding the composting product, the results were positive, showing that this material can be used in ceramic applications.

Abstract Concrete used in civil engineering is a composite obtained from the combination of coarse and fine aggregates, cement and water, and its cost and quality are normally associated to the proportion of its constituents (ceramic formulation), as well as the reduction of water consumption. The aggregates used in concrete may have diverse origins, and the syenite extracted at Pedra Branca Alkaline Massif is one of the materials that can be used for this substitution. In order to do so, a reference formulation of concrete was calculated and optimized using the mathematical models of Andreasen, and syenite was added substituting 25, 50, 75 and 100% of the fine aggregate. In order to maintain the original granulometric distribution, an algorithm was developed to compensate the different particle size distributions. The grain size correction guaranteed the maintenance of the original properties of the concrete, reaching values of mechanical strength above 35 MPa.

Abstract This paper describes the development of ZnO semiconductors applied as photocatalysts for the degradation of water contaminants, with the shape of ceramic pellets thick enough to maintain their structures, prepared by slip casting and sintering. The samples presented porosities around 40% and densities around 3.4 g/cm3, which represented about 61% of the theoretical density of ZnO. After obtaining the ceramic samples, the degradation of Rhodamine B dye by photocatalysis was evaluated in six cycles of degradation. After the cycles, changes in the surface of the samples were verified, possibly due to leaching during photocatalysis since they presented mean grain sizes of 0.61 μm before and 0.36 μm after the photocatalysis. The ceramic ZnO samples were able to satisfactorily degrade Rhodamine B for several cycles, resulting in successful reuse of photocatalysts and increased facility of removing the photocatalysts from the medium after degradation compared to powders in suspensions.

Resumo O porcelanato é um tipo de placa cerâmica de revestimento que vem se destacando atualmente por apresentar boas propriedades estéticas, como a superfície decorada, e mecânicas, como a baixa absorção de água e elevada resistência mecânica e ao ataque químico. As matérias-primas utilizadas para a produção de porcelanato são principalmente a argila e o feldspato. O feldspato é uma das matérias-primas responsáveis pela sinterização durante a queima e auxilia no desenvolvimento de baixa porosidade e elevada resistência ao desgaste da peça cerâmica. Porém, o Brasil apresenta reservas de feldspato em regiões distantes dos centros produtores, fato que encarece a produção deste produto. Dessa forma surge como alternativa a utilização de nefelina para substituir o feldspato, total ou parcialmente, pois este mineral apresenta características bastante similares. Para verificar a influência de tal substituição nas propriedades do porcelanato, inicialmente foi necessário realizar o estudo das propriedades reológicas e físicas da suspensão utilizada na produção. Os resultados encontrados mostraram que a viscosidade da suspensão tende a aumentar com a adição de nefelina, assim como a densidade aparente da peça após a queima.

Abstract The porcelain is a type of ceramic tile which has been contrasted for its good aesthetical, such as decorated surface, and mechanical properties, such as low water absorption and high mechanical and chemical attack resistance. The raw materials used for porcelain tiles production are mainly clay and feldspar. Feldspar is one of the raw materials responsible for the sintering during firing and it helps on the development of low porosity and high wear resistance of the ceramic piece. However, Brazil presents feldspar sources in regions distant from production centers, leading to higher cost for the porcelain tiles production. Thus, nepheline is thought as an alternative to substitute feldspar, totally or partially, since this mineral presents very similar characteristics. In order to verify the influence of this substitution to the properties of the porcelain tiles, it was necessary initially to study the influence of nepheline addition in both rheological and physical properties of the suspension. The results showed that the viscosity of the suspension increases with the addition of nepheline, as well as the apparent density of the fired piece.

Poços de Caldas é um importante centro hidrotermomineral do Brasil, o qual apresenta depósitos de argilas não plásticas para as quais não há registros significativos a respeito da caracterização direcionada destes materiais, o que prejudica estudos de aplicação industrial. Estas argilas não plásticas, não aproveitadas, vêm sendo armazenadas em galpões ou a céu aberto, o que gera um elevado custo para a indústria, além de transformar-se em um passivo ambiental. No presente trabalho realizou-se o estudo químico-mineralógico de seis amostras de argilas de baixa plasticidade, além da caracterização preliminar destas amostras quanto à granulometria, plasticidade e propriedades cerâmicas básicas, visando ampliar os horizontes das investigações destes materiais. Este estudo preliminar mostrou que, de maneira geral, as amostras são compostas por minerais refratários como caulinita e gibbsita, apresentando teores menos significativos de outras fases, como quartzo, vermiculita e illita. Juntamente às análises químicas, estes dados permitiram o agrupamento das matérias-primas em dois grupos em função de sua refratariedade, norteando assim, a caracterização posterior. Dentre as amostras, há material com potencial uso na formulação de massas de porcelanato, além de uma amostra turfosa, cuja aplicação está relacionada à correção de solos.

Poços de Caldas is an important "hydro-thermo-mineral" center in Brazil, where non-plastic clays deposits can be found with no significant records about their characterization, impeding the studies of industrial application. These non-plastic clays, not used, have been stored in sheds or open, which creates a high cost to the industry, and become an environmental liability. In the present work, the chemical-mineralogical study of six samples of non-plastic clays was realized, and also the preliminary characterization of these samples about the grain size, plasticity and basic ceramic properties, to expand the horizons of researches about such materials. This preliminary study showed that, overall, the samples are composed of refractory minerals such as kaolinite and gibbsite, with less significant amounts of other phases such as quartz, illite and vermiculite. The chemical analysis permitted the grouping of raw materials into two groups according to their refractory properties, guiding to the subsequent characterization. Among the samples, there is material with potential use in porcelain formulation, and also a peat sample, which implementation is related to soil correction.

Sistemas de materiais nanoestruturados são mais comumente definidos como aqueles que contêm pelo menos uma característica microestrutural com dimensões nanométricas (até 150 nm). O interesse em nanocompósitos de matriz cerâmica está associado à melhoria nas propriedades mecânicas e ao desgaste. Dispersões de pequenas quantidades de inclusões de zircônia nanométrica em corpo cerâmico de matriz de alumina, propiciam pelo menos um efeito benéfico: inibir o crescimento de grãos durante a sinterização. Um problema enfrentado para essa dispersão é decorrente da tendência das partículas nanométricas formarem aglomerados. Neste trabalho foram utilizados dois procedimentos distintos de dispersão da zircônia na matriz de alumina. A zircônia foi adicionada nas proporções volumétricas de 1%, 3% e 5%. Amostras foram conformadas por prensagem uniaxial seguida de prensagem isostática. Após sinterização, foi determinada a densidade aparente e realizada a caracterização microestrutural das amostras. Os resultados mostram significativa diferença na dispersão das nanopartículas de ZrO2 resultante dos dois procedimentos empregados, sendo que a melhor dispersão aumenta o efeito de refino na microestrutura e permite a obtenção de maior densificação pelo processo de sinterização sem aplicação de pressão.

Nanostructured materials systems have at least one microstructural characteristic with nanometric dimensions (up to 150 nm). The interest on nanocomposites with ceramic matrix can be associated to the improvement of mechanical properties and wear resistance. Dispersion of the small quantities of zirconia provides at least one benefit: the inhibition of grain growth during sintering. One problem related to the dispersion process is the tendency of powder agglomeration. In this work different dispersion procedures of nanometric powders of zirconia in the alumina matrix were investigated. These powders were dispersed (1, 3 and 5% vol) in an alumina matrix. The samples obtained were uniaxial and isostatic pressed, sintered and characterized by measurements of their physical and microstructural properties. The results showed that the improved dispersion of the zirconia particles leads a refinement of the microstructure and densification upon pressureless sintering.