Search results for " minerals"
showing 10 items of 137 documents
Interlamellar Reactions of Tetracalcium Aluminate Hydrates with Water and Organic Compounds
1967
Tetracalcium aluminate hydrates are the first example of layer-structured crystals containing neutral sheets, which are highly capable of interlamellar adsorption of water and neutral organic compounds. In this respect tetracalcium aluminate hydrates present new aspects of the phenomenon of swelling, and bring about the challenge of comparison with the frequently examined clay-organic compounds. This report is concerned with the probable monolayer structure of tetracalcium aluminate hydrate which forms five hydration stages. A summary concerning configuration and properties of adsorption complexes with approximately 500 selected organic substances follows. As far as these substances are hom…
Geochemical characteristics of waters in mineralised area of Peloritani Mountains (Sicily, Italy)
2009
Abstract This paper presents the results of a study on the geochemistry of waters circulating in the mineralised area of the south-eastern sector of Mt. Peloritani (north-eastern Sicily, Italy), aimed at basic understanding of the geochemical processes influencing their chemical composition. Chemico-physical parameters and data on 26 major and minor chemical elements are reported for 103 water samples. Water chemistry is mainly dominated by dissolution of carbonates and hydrolysis of aluminosilicate minerals. Total dissolved salts (TDS) range from 80 to 1398 mg/L. All the waters exhibit E H characteristic of an oxygenated environment. Excluding two samples, which show very high H + activity…
CLOSING THE LOOP: STUDY OF INTEGRATED CYCLES WITH NATURAL AND ARTIFICIAL SOLUTIONS FOR THE PRODUCTION OF ENERGY, MINERALS AND FRESH WATER
Multifunctional halloysite and hectorite catalysts for effective transformation of biomass to biodiesel
2023
Halloysite surface was modified with tetrabutylammonium iodide, and then the obtained nanomaterial was used as support for ZnO nanoparticles. After characterization, the nanomaterial was used as a catalyst for fatty acid methyl esters (FAMEs) production. The recyclability of the nanomaterial was also investigated, and the optimization of reaction conditions by the design of experiments approach was performed as well. In addition, the synthesized nanomaterial was tested as a catalyst for FAME production from a series of waste lipids affording biodiesel in moderate to good yields (35–95%), depending on the matrix. To fully exploit the feasibility of clay minerals as catalysts in biodiesel for…
Lower Aptian climate and recording of the oceanic anoxic event 1a on the terrigenous shelf of the Paris Basin.
2021
Astronomical calibration of the Valanginian and the Hauterivian stages (lower cretaceous) : paleoclimatic and paleooceanographic implications
2013
Orbital floating time scales are proposed for the Valanginian Stage and part of the Hauterivian Stage (Early Cretaceous). These are based on the identification of the eccentricity cycles from spectral analyses performed on high-resolution climatic proxies measured on hemipelagic marl-limestone alternations. Five reference sections were analysed in the Vocontian Basin (SE France), spanning the entire Valanginian. A duration of 5,08 myr is proposed for the Valanginian Stage from the identification of the 405-kyr eccentricity cycle. The time frame proposed, combined with available radiometric ages, shows that the mid-Valanginian 13C positive excursion (namely the Weissert Event) occurs prior …
Three-dimensional solvation structure of ethanol on carbonate minerals
2020
Calcite and magnesite are important mineral constituents of the earth’s crust. In aqueous environments, these carbonates typically expose their most stable cleavage plane, the (10.4) surface. It is known that these surfaces interact with a large variety of organic molecules, which can result in surface restructuring. This process is decisive for the formation of biominerals. With the development of 3D atomic force microscopy (AFM) it is now possible to image solid–liquid interfaces with unprecedented molecular resolution. However, the majority of 3D AFM studies have been focused on the arrangement of water at carbonate surfaces. Here, we present an analysis of the assembly of ethanol – an o…
A feasibility study of table salt production from seawater reverse osmosis brine
2022
The natural hydrous sodium silicates from the northern bank of Lake Chad : occurrence, petrology and genesis
2005
Abstract Hydrous sodium silicates sometimes associated with zeolites, form in an alkaline environment, in which there is a high concentration of dissolved silica. Such an environment existed during the Holocene in N'Guigmi interdunal depressions (Lake Chad), which led to the precipitation of various types of hydrous sodium silicates, including magadiite, kenyaite, and zeolites. Scanning electron and optical microscope observations allow several microstructures to be distinguished. These microstructures result from either precipitation sequences or a transformation along a diagenetic gradient. New petrological, microstructural and geochemical data confirm the transformation of magadiite into…