Low Energy Consumption Synthesis of Nanostructured TiO 2

Titanium dioxide with high specific surface area in the crystalline anatase phase is a promising material for environmental applications. In this work, TiO2 with good applicability for photocatalytic processes has been obtained using the low energy consumption synthesis based on oxidant peroxide method combined with microwave-assisted low temperature hydrothermal treatment. To prepare the material, titanium propoxide, hydrogen peroxide, and isopropyl alcohol were used. The influence of time and temperature during the hydrothermal step on properties like morphology, crystallinity, phase composition, specific surface area, and photocatalytic behavior were investigated. Photoactivity was measured using the methyl orange decomposition method in UV-A light. Increasing temperature during hydrothermal step, photocatalytic properties could be improved. The nanostructured TiO2 particles synthesized at 200°C and 30 min with this method showed photocatalytic activity comparable to commercial Aeroxide® TiO2 P25

X-ray transmission through nanostructured and microstructured CuO materials

This study presents a comparison of the X-ray transmission through microsized and nanosized materials. For this purpose CuO nanoparticles, with 13.4 nm average grain size, and CuO microparticles, with a mean particle size of 56 mu m, were incorporated separately to beeswax in a concentration of 5%. Results show that the transmission through the above material plates with microsized and nanosized CuO was almost the same for X-ray beams generated at 60 and 102 kV tube voltages. However, for the radiation beams generated at 26 and 30 kV tube voltages the X-rays are more attenuated by the nanostructured CuO plates by a factor of at least 14%. Results suggest that the difference in the low energy range may be due to the higher number of particles/gram in the plates designed with CuO nanoparticles and due to the grain size effect on the X-ray transmission. (C) 2010 Elsevier Ltd. All rights reserved.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Brazilian Agency Fapesp (Fundacao de Amparo a Pesquisa do Estado de Sao Paulo)[2010/06814-4]Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)CNPq[307095/2008-8

Avaliação da adição de resíduos de vidro sodo-cálcico e erva-mate em matriz cerâmica

Resumo O presente trabalho avaliou os efeitos da adição de resíduos de vidro sodo-cálcico e de erva-mate sobre a absorção de água, porosidade e resistência mecânica de um material cerâmico. Os pós homogeneizados foram compactados por prensagem uniaxial e submetidos a queima de 900 e 1100 °C a 2 °C.min-1. Os resultados mostraram que a adição de vidro e erva-mate à argila produziu materiais cerâmicos com retração linear entre 0,3 e 6%, absorção de água entre 5,3 e 34%, porosidade aparente de até 41% e resistência mecânica entre 0,5 e 20 MPa. Os materiais queimados a 1100 °C foram os que obtiveram as melhores combinações de propriedades, podendo ser aplicados na produção de blocos, telhas ou revestimento cerâmico de acordo com as necessidades específicas da aplicação