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

Composite Films of Arabinoxylan and Fibrous Sepiolite: Morphological, Mechanical, and Barrier Properties

Hemicelluloses represent a largely unutilized resource for future bioderived films in packaging and other applications. However, improvement of film properties is needed in order to transfer this potential into reality. In this context, sepiolite, a fibrous clay, was investigated as an additive to enhance the properties of rye flour arabinoxylan. Composite films cast from arabinoxylan solutions and sepiolite suspensions in water were transparent or semitransparent at additive loadings in the 2.5-10 wt % range. Scanning electron microscopy showed that the sepiolite was well dispersed in the arabinoxylan films and sepiolite fiber aggregation was not found. FT-IR spectroscopy provided some evidence for hydrogen bonding between sepiolite and arabinoxylan. Consistent with these findings, mechanical testing showed increases in film stiffness and strength with sepiolite addition and the effect of poly(ethylene glycol) methyl ether (mPEG) plasticizer addition. Incorporation of sepiolite did not significantly influence the thermal degradation or the gas barrier properties of arabinoxylan films, which is likely a consequence of sepiolite fiber morphology. In summary, sepiolite was shown to have potential as an additive to obtain stronger hemicellulose films although other approaches, possibly in combination with the use of sepiolite, would be needed if enhanced film barrier properties are required for specific applications.</p

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

Development of nanostructrured multifunctional glazes

Este trabajo ha obtenido el premio Alfa de oro en la Feria Internacional de Cerámica CEVISAMA 2009[ES] El desarrollo de nuevos esmaltes con características innovadoras para la industria de pavimentos y revestimientos cerámicos se ha realizado mediante la dispersión de nanopartículas sobre partículas matriz basadas en fibras de sepiolita de diámetro nanométrico, <50 nm. La sepiolita es una arcilla fibrilar de composición compatible con el esmalte. Los aspectos más relevantes de la investigación realizada han permitido acondicionar las partículas matrices para soportar y proteger diferentes tipos de nanopartículas dispersas de naturaleza metálica u oxídica. Los esmaltes desarrollados tienen la cualidad de encontrarse nanoestructurados y ser multifuncionales, ya que pueden combinarse en un solo esmalte diferentes propiedades como la de tener aspecto metalizado, propiedades hidrofóbicas, bactericidas, fungicidas y de autolimpieza. El concepto de nanopartículas soportadas utiliza de forma eficiente los procesos actuales de tecnología de nanopartículas para obtener multifuncionalidades en los esmaltes, ofreciendo producto cerámico innovador y de mayor valor añadido.[EN] The development of new glazes with innovative characteristics for the tile industry was afforded by using disperse nanoparticles on host sepiolite particles. Sepiolite clay has fibrillar morphology with a diameter <50 nm and with a composition compatible with the glaze. The host particles were conditioned to support and to protect different disperse nanoparticles having metallic or oxidic nature. The developed glazes possess a nanostructure which is responsible for different properties. Different functionalities could be combined in a single glaze as a multifunctional glaze: metallic aspect, hydrophobic response, bactericide and fungicide properties, and self cleaning characteristics. The efficiency of the supported nanoparticles allows the use of the nanoparticles technology to obtain multifunctional glazes and powered the innovations into the tile product with added value.Peer reviewe

Synergistically ceramization of rubber system for fire safety cable by sepiolite functionalized with boron-based nanoparticles

In this research, a novel ethylene propylene diene monomer rubber (EPDM) formulation for cable with high ceramization efficiency was prepared by the addition of functionalized sepiolite with boron fluxing compound nanoparticles (SEPTB) obtained by precipitation route. Non-functionalized sepiolite (SEP) has been incorporated to the system for reference. EPDM materials were characterized by standardized tests measuring their behavior against fire and important improvements were observed, especially in terms of smoke production (25% reduction of the smoke production compared with the formulation using SEP) presenting a remarkable behaviour against dripping and self-extinction when a flame is directly applied. The mechanism of ceramization under fire conditions was discussed. It was found that EPDM system with SEPTB additive transformed into a rigid ceramic after treating at 1000 °C. In this particular case, the ceramization was more efficient due to the sepiolite transformation to enstatite at lower temperatures (∼750 vs ∼850 °C) combined with the “in situ” formation of a glassy phase which notably enhances the reinforcement of the char layer by forming a reinforcing 3D enstatite fibers net structure that reduces smoke production and even totally avoids the dripping of melted polymer by the action of the heat in a fire event. This work provides new insights for the preparation of high-performance synergist additive based on sepiolite for the enhancement of fire retardance of EPDM system for cable applications. Resumen: En esta investigación, se ha preparado una nueva formulación de caucho etileno-propileno-dieno (EPDM) para cable con un efecto de ceramificación más eficiente mediante la adición de sepiolita funcionalizada con nanopartículas de un compuesto fundente de boro (SEPTB) obtenidas por vía de precipitación. La sepiolita no funcionalizada (SEP) se incorporó al sistema del cable como referencia. Los materiales de EPDM fueron caracterizados mediante ensayos estandarizados midiendo su comportamiento frente al fuego y se observaron importantes mejoras, especialmente en términos de producción de humos (reducción del 25% de la producción de humos respecto a la formulación utilizando SEP) presentando un notable comportamiento frente al goteo y autoextinción cuando se aplica directamente una llama. Se propone el mecanismo de ceramificación en condiciones de fuego. Se comprobó que el sistema EPDM con aditivo SEPTB se transformaba en una cerámica rígida tras tratarlo a 1.000 °C. En este caso, la ceramificación fue más eficiente debido a la transformación de sepiolita en enstatita a temperaturas más bajas (∼750 vs ∼850 °C) combinada con la formación in situ de una fase vítrea que mejora notablemente el refuerzo de la capa de carbonilla mediante la formación de una estructura de red 3D de fibras de enstatita que actuaba como refuerzo reduciendo la producción de humo e incluso evitando totalmente el goteo de polímero fundido por la acción del calor en un evento de incendio. Este trabajo aporta nuevos conocimientos para la preparación de aditivos sinérgicos de alto rendimiento basados en sepiolita para la mejora de la retardancia al fuego del EPDM

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