Hydrotalcites: A Highly Efficient Ecomaterial For Effluent Treatment Originated From Carbon Nanotubes Chemical Processing

It has been reported that a mixture of carboxylated carbonaceous fragments (CCFs), so called oxidation debris, are generated during carbon nanotubes chemical processing using oxidant agents such as HNO3. The elimination of these fragments from carbon nanotubes surface has been point out to be a crucial step for an effective functionalization of the nanotubes as well as for improving the material. However, this process can introduce a potential environmental problem related water contamination because these CCFs can be viewed as a mixture of carbonaceous polyaromatic systems similar to humic substances and dissolved organic matter (DOM). The negative aspects of humic substances and DOM to water quality and wastewater treatment are well known. Since carbon nanotubes industry expands at high rates it is expected that effluent containing oxidation debris will increase since HNO3 chemical processing is the most applied method for purification and functionalization of carbon nanotubes. In this work, we have demonstrated that Hydrotalcites (HT) are highly efficient to remove oxidation debris from effluent solution originated from HNO3-treated multiwalled carbon nanotubes. 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Study of the properties of supported Pd catalysts for steam and autothermal reforming of methane

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)The effect of support kind on the structure, surface properties and catalytic behavior of Pd catalysts supported on alumina and mixed La2O3-Al2O3 oxides, prepared by impregnation and sol-gel method was studied. It was found that the catalytic performances of Pd catalysts in steam reforming (SR) and autothermal reforming (AIR) of methane were significantly affected by the kind of support. The highest specific reaction rate and TOFs(CH4), of La-containing Pd catalysts in SRM were related to the electronic interaction between Pd and modified alumina support surface with La oxide species and formation of Pd-0[Pd delta+OxLa] like species, promoting the CH4 activation and carbon oxidation. Despite the filamentous carbon formation these catalysts exhibited the highest activity and stability in AIR caused by the presence of small Pd particles with average particle size of about 14-17 nm. It was shown that the wide particle size distribution up to 70 nm and the formation of encapsulated carbon species are responsible for the fast deactivation of non-La promoted Pd/A1 catalyst. (C) 2014 Elsevier B.V. All rights reserved.The effect of support kind on the structure, surface properties and catalytic behavior of Pd catalysts supported on alumina and mixed La2O3–Al2O3oxides, prepared by impregnation and sol–gel method was studied. It was found that the catalytic performances475256269Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq