ABSTRACT
Pyrophyllite is the least studied natural clay in terms of its potential in biomedical applications, although there are many deposits of this aluminosilicate around the world. Genotoxicity study was performed in vitro for this mineral. Subsequently, Wister rats were exposed to the pyrophyllite micronized to below 100 µm. After the exposure period, histology of the lung, liver, kidney and gastric tissues were performed, followed by the stereological and hematological analysis. The physicochemical analyses revealed typical XRD characteristics of pyrophyllite clay with particle-size distribution ranging 50 nm-100 µm with stable mineral composition and unique buffering property to pH around 8. The results showed that there were no cytotoxic effects on to THP-1 cells, or genotoxicity of pyrophyllite measured by the Comet assay. In vivo studies are accompanied by the thorough physicochemical characterization of the micronized pyrophyllite. Histology of the lung tissue proved presence of an inflammatory reaction. On the other hand, gastric tissue has shown the selective accumulation of nanoparticles in enterocytes of the stomach only, as supported by ultrastructural analysis. Liver and kidney tissues have shown tolerability for pyrophyllite particles. The results give directions for further comprehensive studies of potential biomedical applications of the pyrophyllite.
Subject(s)
Aluminum Silicates , Biocompatible Materials , Kidney , Liver , Particle Size , Rats, Wistar , Animals , Rats , Biocompatible Materials/chemistry , Aluminum Silicates/chemistry , Nanoparticles/chemistry , Humans , Materials Testing , Gastric Mucosa/metabolism , Male , X-Ray Diffraction , Comet Assay , Clay/chemistryABSTRACT
Two routes of preparation of mesoporous Ni-alumina materials favoring the intermediate formation of nanostructured nickel-aluminate are presented. The first one involves an aluminum containing MOF precursor used as sacrificial template to deposit nickel while the second is based on a one-pot synthesis combined to an EISA method. As shown by a set of complementary techniques, the nickel-aluminate nanospecies formed after calcination are homogeneously distributed within the developed mesoporous alumina matrices whose porous characteristics vary depending on the preparation method. A special attention is paid to electron-microscopy observations using especially STEM imaging with high chemical sensitivity and EDS elemental mapping modes that help visualizing the extremely high nickel dispersion and highlight the strong metal anchoring to the support that persists after reduction. This leads to active nickel nanoparticles particularly stable in the reaction of dry reforming of methane.
Subject(s)
Aluminum Oxide/chemistry , Carbon Dioxide/chemistry , Metal Nanoparticles/chemistry , Methane/chemistry , Catalysis , Nanostructures/chemistry , Porosity , Surface PropertiesABSTRACT
The successive steps occurring during conversion of methylbutynol (MBOH) on a basic NaX zeolite catalyst were characterized by combined micro-GC and operando DRIFT spectroscopy, associated to TPD-MS experiments. These techniques permit to reveal a very strong and fast initial decrease in MBOH consumption, associated to some water desorption and to a deficit in acetone that is a product formed together with acetylene, in agreement with the basic route. The origin of deactivation, the nature and reactivity of the adsorbed compounds and their relative strengths of adsorption are discussed on the basis of the evolution of the operando DRIFT spectra with time on stream and next upon keeping the used catalyst in static then under flowing N(2). The FTIR signatures of the three different modes of MBOH adsorption are determined and only the mode involving a zeolite acid-base pair is found reactive. Aldolic condensation is identified but solely to a minor extent in flowing conditions of the reaction whereas it is significantly enhanced in static. Thus, the apparent initial deactivation can be ascribed mainly to MBOH adsorption.
ABSTRACT
NO2 disproportionation on alkaline zeolites is used to generate nitrosonium (NO+) and nitrate ions on the surface, and the infrared vibrations observed are very sensitive to the cation chemical hardness and to the basicity of zeolitic oxygen atoms.
