Combustion Synthesis of Ultrafine Powders of Co3O4 for Selective Surfaces of Solar Collectors

Solar selective paints, with the addition of Co3O4 as a pigment, are used to improve energetic efficiency in solar collectors. Although Co3O4has been obtained by different methods, references about combustion synthesis are scarce. Co3O4 powders have been synthesized by stoichiometric and non-stoichiometric routes using aspartic acid (Asp) or tri-hydroxi-methyl-aminomethane (Tris) as fuels. The samples were calcined in air at 500 °C. They were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, differential scanning calorimetry, Fourier transform infrared spectrum and the specific surface area of the samples was determined by means of the Brunauer–Emmett–Teller technique. The optical properties of pigments were assessed by means of a spectrophotometer. In all cases, powders exhibited the crystalline structure of Co3O4. A minimum crystallite average size of 29 nm was observed for powders obtained by the “stoichiometric/Asp” combustion route, while a maximum value of 41 nm was stated for powders obtained by the “non-stoichiometric/Asp” combustion process. The average particle size ranged between 50 and 100 nm. The powders obtained by the“stoichiometric/Asp” method were selected to study their optical properties; their solar absorption value was 86%. Solar selective surfaces composed by Co3O4 pigments and an alkyd resin were obtained and applied over copper or aluminum substrates. In both cases, solar absorptance was of 93% and comparable with similar solar selective surfaces, but the thermal emittance value was higher than 90%, as a consequence of the large width of the films

Estudio y comparación de alternativas de fin de vida aplicadas a palas de aerogeneradores, empleando metodología de análisis de ciclo de vida

En la actualidad, la industria eólica ha avanzado en la investigación y el empleo de nuevos materiales en la fabricación de aerogeneradores, aunque no han evaluado igualmente como serán tratados los mismos al finalizar su vida útil.En este trabajo se presenta el Análisis de Ciclo de Vida (ACV) de las palas de un aerogenerador, mediante siete alternativas de disposición fin: dos de Incineración, una de Relleno, dos de Reciclado Químico: Pirolisis y Lecho Fluidizado respectivamente, una de Reciclado Mecánico y una de Reúso). De las conclusiones se destaca la identificación de los procesos con menor impacto ambiental como alternativa de fin de vida. Estos son: reciclado químico a través de un Lecho Fluidizado, el Reciclado Mecánico y el Reúso. Finalmente, la alternativa de Reúso es planteada a través de un caso concreto que indica cómo se pueden reutilizar las palas reduciendo al mínimo el consumo de energía, el empleo de materiales adicionales y la generación de desechos.Recently, wind industry has advanced on research and the employment of new materials for the equipment manufacturing. However, there has not been the same progress related to the final disposal of materials at the end of their life. This work proposes a Life Cycle Assessment (LCA) of turbine rotor blades. It presents seven alternatives of final disposal (two alternatives of Incineration, one of the Landfill, two of Chemical Recycling: Pyrolysis and Fluidized Bed respectively, one of Mechanical Recycling and one of Reuse). As main conclusions, we can identify those processes that will present the lowest environmental impact as an ended life alternative. They are the following: Chemical Recycling through Fluidized Bed, Mechanical Recycling and Reuse. Finally, the Reuse alternative is analyzing through a case that indicates how the rotor blades have been reused by minimizing: the energy consumed, the employment of additional materials and the waste generation.Asociación Argentina de Energías Renovables y Medio Ambiente (ASADES

Combustion synthesis of ultrafine powders of Co₃O₄ for selective surfaces of solar collectors

Solar selective paints, with the addition of Co₃O₄ as a pigment, are used to improve energetic efficiency in solar collectors. Although Co3O4 has been obtained by different methods, references about combustion synthesis are scarce. Co₃O₄ powders have been synthesized by stoichiometric and non-stoichiometric routes using aspartic acid (Asp) or tri-hydroxi-methyl-aminomethane (Tris) as fuels. The samples were calcined in air at 500 °C. They were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, differential scanning calorimetry, Fourier transform infrared spectrum and the specific surface area of the samples was determined by means of the Brunauer–Emmett–Teller technique. The optical properties of pigments were assessed by means of a spectrophotometer. In all cases, powders exhibited the crystalline structure of Co₃O₄. A minimum crystallite average size of 29 nm was observed for powders obtained by the “stoichiometric/Asp” combustion route, while a maximum value of 41 nm was stated for powders obtained by the “nonstoichiometric/ Asp” combustion process. The average particle size ranged between 50 and 100 nm. The powders obtained by the “stoichiometric/Asp” method were selected to study their optical properties; their solar absorption value was 86%. Solar selective surfaces composed by Co₃O₄ pigments and an alkyd resin were obtained and applied over copper or aluminum substrates. In both cases, solar absorptance was of 93% and comparable with similar solar selective surfaces, but the thermal emittance value was higher than 90%, as a consequence of the large width of the films.Centro de Investigación y Desarrollo en Ciencias Aplicada

Estudio y comparación de alternativas de fin de vida aplicadas a palas de aerogeneradores, empleando metodología de análisis de ciclo de vida

En la actualidad, la industria eólica ha avanzado en la investigación y el empleo de nuevos materiales en la fabricación de aerogeneradores, aunque no han evaluado igualmente como serán tratados los mismos al finalizar su vida útil.En este trabajo se presenta el Análisis de Ciclo de Vida (ACV) de las palas de un aerogenerador, mediante siete alternativas de disposición fin: dos de Incineración, una de Relleno, dos de Reciclado Químico: Pirolisis y Lecho Fluidizado respectivamente, una de Reciclado Mecánico y una de Reúso). De las conclusiones se destaca la identificación de los procesos con menor impacto ambiental como alternativa de fin de vida. Estos son: reciclado químico a través de un Lecho Fluidizado, el Reciclado Mecánico y el Reúso. Finalmente, la alternativa de Reúso es planteada a través de un caso concreto que indica cómo se pueden reutilizar las palas reduciendo al mínimo el consumo de energía, el empleo de materiales adicionales y la generación de desechos.Recently, wind industry has advanced on research and the employment of new materials for the equipment manufacturing. However, there has not been the same progress related to the final disposal of materials at the end of their life. This work proposes a Life Cycle Assessment (LCA) of turbine rotor blades. It presents seven alternatives of final disposal (two alternatives of Incineration, one of the Landfill, two of Chemical Recycling: Pyrolysis and Fluidized Bed respectively, one of Mechanical Recycling and one of Reuse). As main conclusions, we can identify those processes that will present the lowest environmental impact as an ended life alternative. They are the following: Chemical Recycling through Fluidized Bed, Mechanical Recycling and Reuse. Finally, the Reuse alternative is analyzing through a case that indicates how the rotor blades have been reused by minimizing: the energy consumed, the employment of additional materials and the waste generation.Fil: Rivarola, A.. Universidad Tecnológica Nacional; ArgentinaFil: Torres, Laura. Universidad Tecnológica Nacional; ArgentinaFil: Rivarola, A. M.. Universidad Tecnológica Nacional; ArgentinaFil: Berrios, G.. Universidad Tecnológica Nacional; ArgentinaFil: Gardey Merino, María Celeste. Universidad Tecnológica Nacional; ArgentinaFil: Gatica, P.. Universidad Tecnológica Nacional; ArgentinaFil: Arena, Alejandro Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Ciencias Humanas, Sociales y Ambientales; Argentina. Universidad Tecnológica Nacional; Argentin

Nanostructured aluminium oxide powders obtained by aspartic acid-nitrate gel-combustion routes

In this work, two new gel-combustion routes for the synthesis of Al2O3 nanopowders with aspartic acid as fuel are presented. The first route is a conventional stoichiometric process, while the second one is a non-stoichiometric, pH-controlled process. These routes were compared with similar synthesis procedures using glycine as fuel, which are well-known in the literature. The samples were calcined in air at different temperatures, in a range of 600-1200 °C. They were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and BET specific surface area. Different phases were obtained depending on the calcination temperature: amorphous, γ (metastable) or α (stable). The amorphous-to-γ transition was found for calcination temperatures in the range of 700-900 °C, while the γ-to-α one was observed for calcination temperatures of 1100-1200 °C. The retention of the metastable γ phase is probably due to a crystallite size effect. It transforms to the α phase after the crystallite size increases over a critical size during the calcination process at 1200 °C. The highest BET specific surface areas were obtained for both nitrate-aspartic acid routes proposed in this work, reaching values of about 50 m2/g. © 2009 Elsevier B.V. All rights reserved.Fil: Gardey Merino, María Celeste. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Científicas y Tecnológicas. Laboratorio de Investigaciones y Servicios Ambientales Mendoza; Argentina. Universidad Tecnológica Nacional; ArgentinaFil: Lascalea, Gustavo Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Científicas y Tecnológicas. Laboratorio de Investigaciones y Servicios Ambientales Mendoza; ArgentinaFil: Sánchez, Laura M.. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones Científicas y Técnicas de las Fuerzas Armadas. Centro de Investigaciones en Sólidos; ArgentinaFil: Vazquez, Patricia Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Ciencias Aplicadas "Dr. Jorge J. Ronco". Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Ciencias Aplicadas; ArgentinaFil: Cabanillas, Edgardo Domingo. Comisión Nacional de Energía Atómica. Centro Atómico Constituyentes; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Lamas, Diego Germán. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones Científicas y Técnicas de las Fuerzas Armadas. Centro de Investigaciones en Sólidos; Argentin

Combustion syntheses of Co3O4 powders using different fuels

Co3O4 powders are used as pigment in solar selective paints. In this work, two new gel-combustion processes for the synthesis of Co3O4 nanopowders with lysine (Lys) or ethylenediaminetetraacetic acid (Edta) as fuel are presented. The first route is a conventional, stoichiometric process, while the second one is a non-stoichiometric, pH-controlled process. The samples were calcined in air at 500 ºC. They were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectrum (FTIR), Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) and the optical properties of the pigments were assessed with a spectrophotometer. In all cases, powders exhibited the Co3O4 crystalline structure. A minimum crystallite average size of 19 nm for powders obtained by the ?stoichiometric/Lys? combustion route was observed, meanwhile, a maximum value of 47 nm was stated for powders obtained by the ?non-stoichiometric/Edta? combustion process. The average particle size ranged between 50 and 100 nm. The powders obtained by the stoichiometric nitrate?lysine route were selected to study its optical properties, their solar absorption was 88%, compared with the references, evidencing their aptitude to be used in solar absorbent paints.Fil: Gardey Merino, Maria Celeste. Universidad Tecnologica Nacional. Facultad Reg.mendoza. Grupo Cliope Energia, Ambiente y Desarrollo Sustentable; ArgentinaFil: Tornello Nasisi, Leonardo D.. Universidad Tecnologica Nacional. Facultad Reg.mendoza. Grupo Cliope Energia, Ambiente y Desarrollo Sustentable; ArgentinaFil: Montoya, William M. . Universidad Tecnologica Nacional. Facultad Reg.mendoza. Grupo Cliope Energia, Ambiente y Desarrollo Sustentable; ArgentinaFil: Urrutia Aguilera, Jesus N. . Universidad Tecnologica Nacional. Facultad Reg.mendoza. Grupo Cliope Energia, Ambiente y Desarrollo Sustentable; ArgentinaFil: Fernandez, Maria Emilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones Científicas y Técnicas de las Fuerzas Armadas. Centro de Investigaciones en Sólidos; ArgentinaFil: Lascalea, Gustavo Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Centro de Investigación y Desarrollo en Ciencias Aplicadas; ArgentinaFil: Vazquez, Patricia Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Centro de Investigación y Desarrollo en Ciencias Aplicadas; Argentin