Search results for "Clay"
showing 10 items of 349 documents
Using organoclay to promote morphology refinement and co-continuity in high-density polyethylene/polyamide 6 blends – Effect of filler content and po…
2010
We investigate the gradual changes of the microstructure of two blends of high-density polyethylene (HOPE) and polyamide 6 (PA6) at opposite composition filled with increasing amounts of an organo-modified clay. The filler locates preferentially inside the polyamide phase, bringing about radical alterations in the micron-scale arrangement of the polymer phases. When the host polyamide represents the major constituent, a sudden reduction of the average sizes of the polyethylene droplets was observed upon addition of even low amounts of organoclay. A morphology refinement was also noticed at low filler contents when the particles distributes inside the minor phase. In this case, however, keep…
Using microtomography, image analysis and flow simulations to characterize soil surface seals
2012
Raindrops that impact on soil surface affect the pore structure and form compact soil surface seals. Damaged pore structure reduces water infiltration which can lead to increased soil erosion. We introduce here methods to characterize the properties of surface seals in a detailed manner. These methods include rainfall simulations, x-ray microtomography, image analysis and pore-scale flow simulations. Methods were tested using clay soil samples, and the results indicate that the sealing process changes several properties of the pore structure.
Contamination Remediation with Soil Amendments by Immobilization of Heavy Metals
2015
Elektroniskā versija nesatur pielikumus
Weathering Products of a Dismantled Variscan Basement. Minero-Chemical Proxies to Insight on Cretaceous Palaeogeography and Late Neogene Palaeoclimat…
2020
This study compares, for the first time, the mineralogy and geochemistry of two residual-clay deposits in NW Sardinia (Nurra district) that formed at different times in tropical and sub-tropical climates. Both deposits represent palaeosols with deep-weathered residual profiles and overlie Mesozoic carbonate rocks that were deposited on the south European palaeomargin. The older alterite is Cenomanian–Turonian in age and grades upward into a horizon of karstic bauxite, whereas the younger unit occurs within alluvial deposits of Late Neogene age. The Cretaceous palaeosol represents the precursor of the overlying bauxite and formed from unknown sedimentary parent rocks. In contrast, the Messin…
Effects of compositional and textural characteristics of clay based plasters on the control of indoor relative humidity
2015
Air humidity in contained spaces has a significant impact on health of inhabitants. The control capability of indoor relative humidity (RH) of clay-based plasters was tested on a series of commercially available products specifically designed for wall undercoating and on a natural earth collected in the surrounding area of Palermo. The innovative practice of ‘‘green building’’, since several years, led the interest of research to recyclable and reusable traditional materials that, in several cases, are a sustainable alternative to concrete and lime mortars. Earthen plasters, in general, have the ability to balance indoor humidity like no other classic building materials. The studied samples…
Transformation of clay-sized minerals in soils exposed to prolonged regular alternation of redox conditions
2016
Abstract The direction of the transformation of Fe-bearing minerals under harshly changing redox conditions is still under debate. Some studies suggest preferential accumulation of weakly crystalline Fe oxides while other studies showed that repeated redox cycles favour the presence of crystalline phases. Since characterized by distinct redox cycles, paddy soils are ideal for studying redox-related transformations of Fe oxides and Fe-bearing clay minerals. We analysed changes in the Fe mineral assemblage upon long-term reduction–oxidation cycles along a chronosequence of 100, 700, and 2000-year-old paddy soils developed on comparable parent material relative to two non-irrigated counterpart…
Mineralverwitterung, tonmineralbildung und rubefizierung in Terrae calcis der slowakei Ein beitrag zum paläoklimatischen aussagewert von kalkstein-Ro…
1984
Mineral weathering, clay mineral formation and rubefication of Terrae calcis in Slovakia — A contribution to paleoclimatic evidence of limestone Rotlehm (terra rossa) in Central Europe Limestone Rotlehm (Terra rossa) is very often interpreted as a product of intensive mineral weathering and clay formation under subtropic (to tropic) climate. Especially the formation of hematite in soils as the main process of rubefication is generally believed to occur only in warm climates with a seasonal alternation of precipitation and drought. Fossil or relict Terrae rossae in Central Europe are therefore very often considered as witnesses of a corresponding paleoclimate. On the other side many authors …
Direct chemical grafted curcumin on halloysite nanotubes as dual-responsive prodrug for pharmacological applications
2016
Covalently functionalized halloysite nanotubes (HNTs) were successfully employed as dual-responsive nanocarriers for curcumin (Cur). Particularly, we synthesized HNT-Cur prodrug with a controlled curcumin release on dependence of both intracellular glutathione (GSH) and pH conditions. In order to obtain HNT-Cur produgs, halloysite was firstly functionalized with cysteamine through disulphide linkage. Afterwards, curcumin molecules were chemically conjugated to the amino end groups of halloysite via Schiff's base formation. The successful functionalization of halloysite was proved by thermogravimetric analysis, FT-IR spectroscopy, dynamic light scattering and scanning electron microscopy. Ex…
Orientation of charged clay nanotubes in evaporating droplet meniscus.
2015
© 2014 Elsevier Inc. During drying, an aqueous suspension of strongly charged halloysite clay nanotubes concentrates at the edge of the droplet ("coffee-ring" effect) which provides alignment of the tubes along the liquid-substrate contact line. First, the surface charge of the nanotubes was enhanced by polyanion adsorption inside of the lumen to compensate for the internal positive charges. This increased the magnitude of the ξ-potential of the tubes from -36 to -81mV and stabilized the colloids. Then, colloidal halloysite was dropped onto the substrate, dried at 65°C and after a concentration of ~0.05mgmL-1 was reached, the alignment of nanotubes occurred starting from the droplet edges. …
HALLOYSITE NANOTUBES AS SUPPORT FOR METAL NANOPARTICLES FOR CATALYTIC APPLICATION
2017
Halloysite (HNT) is a natural clay that, in the last years, has shown an important increasing on various applications in different field of interesting. Chemically similar to kaolin, it shows the predominately rolled shape, to form multilayers tubes of nanometric dimensions. The different chemical composition of the inside lumen (Al-OH) surface and outside (Si-O) give to the tubes a partial negative charge outside and positive inside. In this way, it is possible to get different interactions of different molecules or systems selectivity on one or another surface. The selective functionalization, covalent or not, of the HNT lumen or outer surface, gives the possibility to the nanotubes to fu…