Occupational exposure to nano-TiO2 in the life cycle steps of new depollutant mortars used in construction

The present work is focused on the measurement of workers exposure to nano-TiO2 in the life cycle steps of depollutant mortars. It has been done in the framework of the SCAFFOLD project, which aims at the management of potential risks arising from the use of manufactured nanomaterials in construction. Main findings can be summarized as follows: (1) The occupational exposure to nano- TiO2 is below 0.3 mg/m3 for all measured scenarios. The highest concentrations were measured during the cleaning task (in the nano- TiO2 manufacturing process) and during the application (spraying) of depollutant coatings on a wall. (2) It was found a high release of particles above the background in several tasks as expected due to the nature of the activities performed. The maximum concentration was measured during drilling and during adding powder materials (mean total particle concentration up to 5.591E+04 particles/cm3 and 5.69E+04 particles/cm3). However, considering data on total particle concentration released, no striking differences have been observed when tasks have been performed using conventional materials in the sector (control) and when using materials doped with nano-objects.European Commission's FP

Glass silicate from Cr and Ni high level galvanic waste

[ES] La eliminación de los residuos industriales tóxicos, es en la actualidad un objetivo prioritario a nivel mundial. Para el caso particular de los residuos sólidos galvánicos, su alto contenido en metales pesados resulta perjudicial tanto para la salud como para el medio ambiente. En este trabajo se han obtenido vídrios con un 40% en peso de residuos galvánicos de alto contenido en cromo y níquel. La estabilidad química de los vídrios obtenidos fue comprobada mediante ensayos de resistencia al ataque hidrolítico, ácido y alcalino. Finalmente, los diferentes vídrios fueron caracterizados por diferentes técnicas difración de rayos-X, fluorescencia de rayos-X, espectrometría infrarroja.[EN] The environmental and human health related with harmful industrial waste is nowadays an issue of worldwide great concern. Particularly the case of galvanic solid waste, because of its high content in heavy metals, it is highly harmful from both environmental and human health point of view. In this study, glasses containing up to 40 wt% of galvanic waste with a high content of chromium and nickel were obtained. The chemical stability of these glasses was studied by hydrolytic, alkaline and acid attack. Finally the different glasses were studied by X-ray diffraction, X-ray fluorescence and infrared spectroscopy techniques in order to rationalize and to understand its observed chemical stability.Peer reviewe

High wear resistance white ceramic glaze containing needle like zircon single crystals by the addition of sepiolite n-ZrO2

Sepiolite with homogeneous zirconia nanoparticles distribution has been added to a transparent ceramic glaze to study opacification, mechanical and wear resistance properties. It has been observed that monodispersed zircon single crystals with needle-like shape have been formed in the ceramic glaze. These in situ zircon single crystals give white color and increase opacification (L= 94 vs L= 90), mechanical properties (hardness and toughness) and wear resistance by a factor of 4 compared to the commercial crystalline glaze containing a similar fraction of micrometer commercial zircon. © 2013 Elsevier Ltd.This research has been supported by the Spanish Ministry of Science and Innovation under project DOMINO (CENIT-2007-1001).Peer Reviewe

Magneto-optical Faraday activity in transparent FeCo-sepiolite/polystyrene nanocomposites

FeCo nanoparticles synthesized on sepiolite microparticles were used for the preparation of nanocomposites by melt compounding with polystyrene. Both, the sepiolite fibers and the nanoparticles were free of agglomeration, which allowed preparing nanocomposites with a homogeneous dispersion of the second phases, avoiding the usual agglomeration of the nanoparticles and minimizing light scattering. As a consequence, transparent composites with a high magnetic susceptibility have been obtained. The magneto-optical Faraday activity of these nanocomposites has been studied, finding saturation rotations over 200 rad·m-1 in the visible range. The processing route presented in this work can be easily transferred to industry and allows preparing polymer matrix nanocomposites with no restriction on shape or size and opens the possibility of developing other highly transparent polymer-based nanocomposites. © Springer Science+Business Media 2013.The authors want to acknowledge the Spanish Ministry of Education and Science through projects MAT2011-29174-C02-01 and MAT2011-29174-C02-02.Peer Reviewe

Micro/nano composites: A simple and safe way to fabricate nanomaterials

In this paper we detail how the use of nanoparticles supported or embedded in microparticles (nanostructured powders) may overcome many of the problems of nanoparticle manipulation as well as allowing bulk compacts in which nanoparticles appear monodisperse to be obtained. The main advantage of this procedure is that the possibility to use the well developed knowledge about compounding of microparticles to obtain dense composites instead of developing new methods to handling nanoparticles. The obtained nanostructured powders or dense composites can be used for different applications, such as medical implants, cutting tools, optical devices, magnetic powders, etc. Examples of alumina/nano-zirconia, alumina/nano-YAG, zirconia/nano-nickel, alumina/nano-Ag and sepiolite/nano-(Cu, Au, Ag, Ni and Fe) are also reported

Epitaxial growth of tungsten nanoparticles on alumina and spinel surfaces

International audienceIsolated tungsten nanoparticles (a-W and ß-W phase) were synthesized and epitaxially grown on alumina and spinel particle surfaces with an average tungsten size of =20 nm for a low tungsten content (of =1.5 vol%). Using tungsten (VI) ethoxide alcoholic solutions, tungsten trioxide hydrated precursors were attached to a ceramic grains surface as a nanoparticle coating. High-resolution transmission electron microscopy (HRTEM) micrographs showed epitaxial interfaces between alumina, spinel and metallic tungsten. This epitaxial growth is assumed to be due to the effect of water vapour on the sublimation of ortho-tungstic acid during the reduction process in a hydrogen atmosphere. The planes involved in the epitaxy were found to be (220) Al2O3||(121)W and (311)MgAl2O4||(110) W