This work evaluated the catalytic activity of TiO 2 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.

The mechanical properties of polyester/fiberglass composites were studied. The aim of this work was to evaluate the possibility of reusing the wastes taken from spray-up processing of Paraíba state Industries as reinforcement in polyester matrix composites. Composites with 20, 30, 40, 50 and 60 wt. (%) of recycled fiberglass were prepared by compression molding and compared with polyester/ virgin glass fiber composites. The mechanical properties and water sorption behavior were evaluated. The results showed that fiberglass wastes are promising to be reused in polyester resin composites. The impact strength was excellent. It can be concluded that the reusing of the fiberglass wastes is viable

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RESUMOO dióxido de titânio tem sido bastante investigado para a remoção de poluentes orgânicos. É um material polimórfico, o qual dependendo das condições e tipo de método de síntese empregado na sua preparação pode ser monofásico ou bifásico, com predominância de uma das fases. Sendo assim, este trabalho propõe a avaliação da estrutura, morfologia e atividade fotocatalítica na degradação do corante vermelho de metila por amostras de TiO 2 sintetizado pelo método Pechini com relação de ácido cítrico/cátion metálico de 4:1 e 6:1.As amostras sintetizadas foram calcinadasa 500ºC por 1hora e foram caracterizadas pela técnica de difração de raios X em amostras policristalinas com o uso do método de refinamento Rietveld, análise textural, microscopia eletrônica de varredura e fotocataliticamente em testes de bancada, usando o corante vermelho de metila. Os resultados obtidos mostraram que a amostra 4:1 levou à formação das duas fases, com 89% da fase anatásio e 11% da fase rutilo, enquanto a amostra 6:1 levou apenas à formação da fase anatásio. A amostra 4:1, que apresentou a mistura da fase anatásio e rutilo demonstrou ser mais eficiente fotocataliticamente do que a amostra 6:1.Palavras-chave: fotocatálise heterogênea, vermelho de metila, dióxido de titânio, método Pechini. ABSTRACTTitanium dioxide has been widely investigated in the removal of organic pollutants. It is a polymorphic material which, depending on the conditions and the type of synthetic method used in its preparation may be monophasic or biphasic, with predominance of one of the phases. Therefore, this paper proposes the evaluation of the structure, morphology and photocatalytic activity in the degradation of methyl red dye byTiO 2 samples synthesized by the Pechini method with citric acid/metal cation ratios of 4:1 and 6:1. The synthesized samples were calcined at 500°C for 1 hour and were characterized by X-ray powder diffraction technique by using Rietveld refinement, textural analysis, scanning electron microscopy and photocatalytic test sin bench scale, using methyl red dye. The results showed that the sample 4:1 led to the formation of two phases, 89% anatase and 11% rutile, while the sample 6:1 led only to the formation of the anatase phase. The 4:1 sample, a mixture of anatase and rutile phase, photocatalytically, was more effective than the 6:1 sample.

Avaliação do efeito da temperatura de calcinação nas características estruturais e morfológicas de aluminas sintetizadas pelo método PechiniEffect of calcination temperature on the structural characteristics and morphology of aluminas synthesized by the Pechini RESUMOO presente trabalho tem como objetivo sintetizar alumina pelo método Pechini e avaliar a influência da temperatura de calcinação nas características estruturais e morfológicas das mesmas com o intuito de direcioná-las a distintas aplicações. A relação utilizada na metodologia para o ácido cítrico:cátion metálico foi de 3:1 e as temperaturas de calcinação variaram de 500 a 1200°C em intervalos de 100°C. Os materiais sintetizados foram caracterizados por difração de raios X, distribuição granulométrica e microscopia eletrônica de varredura. Os resultados demonstraram que a variação da temperatura de calcinação alterou a estrutura e a morfologia da alumina. As amostras apresentaram-se amorfas abaixo da temperatura de calcinação a 800ºC, a fase alumina surgiu após a calcinação a 900°C e a fase alfa alumina após 1100°C. O aumento da temperatura na calcinação diminuiu o diâmetro médio dos aglomerados de 17,79 para 13,01 m para as amostras calcinadas a 500 e 1200°C, respectivamente. Quanto à morfologia, a mudança na temperatura de calcinação não alterou de forma significativa o material sintetizado. As partículas estão distribuídas aleatoriamente ao longo das amostras apresentando geometria com aparência de placas em diferentes dimensões depositadas sobre notá-veis aglomerados. As características geradas pelas aluminas possibilitam sua aplicação em membranas, catá-lise, implantes odontológicos, compósitos, etc. Palavras-chave: Alumina, temperatura de calcinação, método Pechini. ABSTRACTThe present work aims to synthesize alumina by Pechini method and evaluate the influence of calcination temperature on structural and morphological characteristics of the same in order to direct them to different applications . The methodology used in relation to citric acid : metal cation was 3:1 and calcination temperatures ranging 500-1200°C in steps of 100°C. The synthesized materials were characterized by X-ray diffraction , particle size distribution and scanning electron microscopy. The results showed that the variation of the calcination temperature altered the structure and morphology of the alumina. The samples had amorphous below the calcination temperature to 800°C, the alumina phase appeared after calcination at 900°C and the alpha alumina phase after 1100°C. The increase in calcination temperature decreased the average diameter of

The zinc oxide varistors are ceramic semiconductor devices doped with some metallic oxides such as: bismuth, nickel, manganese, cobalt, and others. The aim of this work is to characterize the varistors, obtained by the Pechini’s method, regarding their microstructure and electrical features. By using chemical synthesis, it has been produced ceramic powders. The powders have been compacted in the form of pellets and sintered at 1200°C/1h. The samples have been characterized by measurements of J x E, XRD and by SEM. The results show that the powders obtained through Pechini’s synthesis method and calcined at 700°C/1h have a particle size of less than 100 nm. The resulting microstructures show heterogeneous morphologies in a shape of pins and presence of inter and intragrain porosity. The electrically characterized results show that the produced varistors present a nonlinearity coefficient of 21 and breakdown voltage of 1590 V/cm.