Search results for "Kaolin"
showing 10 items of 90 documents
Mix design and mechanical performance of geopolymeric binders and mortars using biomass fly ash and alkaline effluent from paper-pulp industry
2019
Abstract This work investigates the use of biomass fly ash (BFA) and an alkaline effluent (AEF), both generated from the Kraft pulp industry, in the preparation of geopolymeric binders and mortars for construction applications. BFA replaced the metakaolin (MK) while the AEF substituted the distilled water used to dissolve NaOH pellets. The mix design aims to maximize the amount of both the wastes and to optimize the materials properties, such as workability and mechanical performance. At the same time, also the environmental impact decreases enhancing the materials' sustainability and facilitating the circular economy. For the previously optimized BFA/MK ratio (70/30 wt.%) several NaOH/Na2S…
Biopolymer-Targeted Adsorption onto Halloysite Nanotubes in Aqueous Media.
2017
Studies on the adsorption of biopolymers onto halloysite nanotubes (HNTs) in water were conducted. Three polymers with different charges-anionic (pectin), neutral (hydroxypropyl cellulose), and cationic (chitosan)-were chosen. The thermodynamic parameters for the adsorption of polymers onto the HNT surface were determined by isothermal titration calorimetry (ITC). The experimental data were interpreted based on a Langmuir adsorption model. The standard variations in free energy, enthalpy, and entropy of the process were obtained and discussed. Turbidimetry was used to evaluate the stability of functionalized nanoparticles in water. The ζ-potential clarified the surface charge properties of …
XRD Line Broadening Studies on Mullite
1996
An X-ray diffraction microstructural study on 110, 220, 001 and 111 peaks has been performed on mullite in the temperature range of primary mullite formation in order to monitor nucleation and growth process. Considering the crystallinity of the starting kaolinites, a greater disorder of the kaolinite has been found to enhance the mullite formation. Isothermal growth is related to a decrease in the Al 2 O 3 content of mullite.
Nanoporous kaolin
2017
Cellulose nano- and microfibrils (CNF/CMF) grades vary significantly based on the raw materials and process treatments used. In this study four different CNF/CMF grades were combined with kaolin clay pigment particles to form nanoporous composites. The attained composite properties like porosity, surface smoothness, mechanical properties and density properties depended strongly on the raw materials used. In general, higher kaolin content (~80 wt%) led to controllable shrinkage during drying, which resulted in improved dimensional stability of composites, compared to a lower kaolin content (~50 wt%). On the other hand, the use of a plasticizer and a high amount of CNF/CMF was essential to pr…
Prove di controllo di Ceratitis capitata (Wiedemann) in pescheti, aranceti e clementineti biologici
2011
Tests to control Ceratitis capitata (Wiedemann) in organic peach, orange and clementine orchards. The Mediterranean Fruit Fly, Ceratitis capitata (Wiedemann), is considered the key pest of several fruit species in organic farming. Experiments for the control of this pest have been carried out in organic peach orchards (in 2009 on a medium-late ripening cultivar, ‘Bella di Bivona’; in 2011 on a very early ripening one, ‘San Pedro’) testing nets, spinosad and pyrethrum (year 2009), in orange citrus groves (cv. Navelina, early ripening period), comparing spinosad, kaolin and bentonite (years 2009 and 2010) and in a clementine grove (cv. Monreal), using kaolin and bentonite. The very early ripe…
Influence of pH and temperature on the early stage of mica alteration
2012
Mineral dissolution and precipitation reactions actively participate in controlling fluid chemistry during water–rock interaction. In this study, the changes in the biotite and muscovite basal surface nano-morphology were evaluated during interaction with fluids of different pH (pH = 1.1, 3.3 and 5.7) at different temperatures (T =2 5, 120, and 200 C). Results show that at the nanometre scale resolution of the atomic force microscope (AFM), dissolution generates etch pits with a stair-shaped pattern over the (0 0 1) surface. The flux of dissolved elements decreases when pH increases. However, at pH 5.7, a change was found in the flux after 42 h of reaction when abundant gibbsite and kaolini…
Mineral and trace element composition of the Lokpanta oil shales in the Lower Benue Trough, Nigeria
2011
Abstract The concentrations of minerals and trace elements in the Lokpanta oil shale from the Lower Benue Trough, Nigeria have been determined by X-ray diffraction (XRD) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), respectively. X-ray diffraction data were evaluated using the SIROQUANT™ interactive data processing system based on Rietveld interpretation methods. A new method of trace element determination in oil shale, involving LA-ICP-MS analysis of glass beads prepared by fusing oil shale ash on an iridium strip heater was used, and the accuracy of the method was assessed by including a standard shale reference material (SGR-1b) in the analysis program. The…
Iron-clay interactions: Detailed study of the mineralogical transformation of claystone with emphasis on the formation of iron-rich T-O phyllosilicat…
2014
International audience; Iron-minerals-water interactions are of primary importance in the contexts of underground structure engineering (e.g. reactive barriers or deep geological storage) and for the understanding of secondary alteration processes in primitive meteorites. To improve our understanding of these systems, we determine the mineralogical transformations induced by the association of iron and silicates during a cooling through an experimental simulation of iron-clay interactions with a step-by-step procedure in the range of 90 degrees C to 40 degrees C. The run products and solutions are well characterised, by means of different techniques (X-ray diffraction, scanning and transmis…
Nanohydrogel Formation within the Halloysite Lumen for Triggered and Sustained Release
2018
An easy strategy to obtain nanohydrogels within the halloysite nanotube (HNTs) lumen was investigated. Inorganic reverse micelles based on HNTs and hexadecyltrimethylammonium bromides were dispersed in chloroform, and the hydrophilic cavity was used as a nanoreactor to confine the gel formation based on alginate cross-linked by calcium ions. Spectroscopy and electron microscopy experiments proved the confinement of the polymer into the HNT lumen and the formation of calcium-mediated networks. Biological tests proved the biocompatibility of the hybrid hydrogel. The nanogel in HNTs was suitable for drug loading and sustained release with the opportunity of triggered burst release by chemical …
Chemical modification of halloysite nanotubes for controlled loading and release.
2020
Clay minerals have been used for medical purposes from ancient times. Among them, the halloysite nanotube, an aluminosilicate of the kaolin group, is an emerging nanomaterial which possesses peculiar chemical characteristics. By means of suitable modifications, such as supramolecular functionalization or covalent modifications, it is possible to obtain novel nanomaterials with tunable properties for several applications. In this context the covalent grafting of suitable organic moieties on the external surface or in the halloysite lumen has been exploited to improve the loading and release of several biologically active molecules. The resulting hybrid nanomaterials have been applied as drug…