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Interaction Between Soil Particles and Soil Solution
Published in Shingo Iwata, Toshio Tabuchi, Benno P. Warkentin, Soil-Water Interactions, 2020
Shingo Iwata, Toshio Tabuchi, Benno P. Warkentin
Kaolinite The elementary layer of kaolinite consists of a silica sheet and an alumina sheet (Fig. 2.7) sharing the top oxygens of the silica tetrahedra (Fig. 2.5a). The elementary layer is three oxygen atoms thick; one face consists of a hydroxyl layer from the alumina sheet, and the other an oxygen layer from the silica sheet (Fig. 2.7). A kaolinite particle is composed of layers held together by hydrogen bonding between the hydroxyl and the oxygen layer (Fig. 2.7). As the force due to the hydrogen bond is strong, hydration between layers does not occur naturally.
Dimensionality Transformation of Layered Materials toward the Design of Functional Nanomaterials
Published in Kazuhiro Shikinaka, Functionalization of Molecular Architectures, 2018
Nanoscrolls are artificially prepared by exfoliation and subsequent scroll of layered materials. Although many of layered materials can be exfoliated by conventional methods, only part of them can be transformed into nanoscrolls. A natural nanoscroll, halloysite consists of the sheet which is the same as the layer structure of a natural clay mineral, kaolinite [58]. Kaolinite is a 1:1 type clay mineral whose sheet consists of a tetrahedral sheet containing silicon and an octahedral sheet containing aluminum, whereas most other clay minerals have 2:1 type structure in which two tetrahedral sheets are attached on both sides of an octahedral sheet. The kaolinite sheet rolls up along the a axis to make the tetrahedral sheet to the outside [59–61]. The tetrahedral sheet has intrinsically larger lattice constant than that of the octahedral sheet; thus, the tetrahedral sheet is bonded with the octahedral sheet, reducing the lattice constant by a tetrahedral rotation. Because the misfit is relaxed by curling, halloysite nanoscroll is formed spontaneously. Consequently, the differentiated tensions on both sides of a nanosheet are the main driving force for the formation of nanoscrolls.
Soil and Groundwater PFAS Remediation
Published in David M. Kempisty, Yun Xing, LeeAnn Racz, Perfluoroalkyl Substances in the Environment, 2018
David F. Alden, John Archibald, Gary M. Birk, Richard J. Stewart
The presence of kaolinite in RemBind allows sorption of cationic PFAS. Kaolinite is an aluminosilicate clay mineral comprising one octahedral sheet of aluminum-oxygen linked to one tetrahedral sheet of silica-oxygen bonds. It contains net a negative charge due to substitution of lower-valence atoms into the aluminum octahedral position (such as Mg+2) or the Si tetrahedral positions (e.g., Al+3). At low pH, it may also contain some positive charges located at the unpaired oxygen atoms at the edge of the crystal lattice, but these would be small in magnitude when compared with the large positive charge afforded by the aluminum hydroxide in RemBind.
A retrospect on recent research works in the preparation of zeolites catalyst from kaolin for biodiesel production
Published in Biofuels, 2023
Jane Mngohol Gadin, Eyitayo Amos Afolabi, Abdulsalami Sanni Kovo, Ambali Saka Abdulkareem, Moritiwon Oloruntoba James
Kaolin clay is made up of about 10–95% kaolinite, which is a 1:1 layered phyllosilicate clay mineral. Kaolinite consist of two layers, one of SiO4 tetrahedral and the other of gibbsite-like Al(OH)4 octahedral amalgamated through longitudinal sideline chains to form a di-octahedral structure [109]. The chemical formula for kaolinite is Si2Al2O5(OH)4 (Al2O5Si2·2H2O or Al2O3.2SiO5·2H2O) theoretically. Present as impurities in kaolin are oxide of metals (such as Fe2O3, CaO, P2O5, MnO, Na2O, MgO, K2O and TiO2), quartz and mica [110]. Kaolin has found usefulness in several industrial processes such as adsorption, ion exchange, de-colorization, catalysis, catalyst supports and modification of catalysts [111].
Diverse provenance of the Lower Cretaceous sediments of the Eromanga Basin, South Australia: constraints on basin evolution
Published in Australian Journal of Earth Sciences, 2021
E. Baudet, C. Tiddy, D. Giles, S. Hill, G. Gordon
The dominant clay mineral in the Cadna-owie Formation is kaolinite. Kaolinite is found in deeply weathered areas with elevated rainfall either in wet tropical conditions or in cooler climates (Beckmann et al., 2005; Gibson et al., 2000; Roy & Roser, 2013; Viscarra Rossel, 2011). Unexposed sections of the Bulldog Shale, Coorikiana Sandstone and Oodnadatta Formation are dominated by the clay mineral montmorillonite. In the case of surface exposures, kaolinite is the dominant clay and likely a result of strong acid surface weathering (Baudet et al., 2018; Kear & Hamilton-Bruce, 2011). Smectite minerals such as montmorillonite can be associated with the weathering of ferromagnesian minerals, are more likely to form in low relief/flat areas (Viscarra Rossel, 2011) and can be correlated to warm and semi-arid conditions (Macphail, 2007). In general, the dominance of montmorillonite within the Bulldog Shale, the Coorikiana Sandstone and the Oodnadatta Formation is suggestive of a more arid and warmer climate than at the time of deposition of the more kaolinite-rich Cadna-owie Formation.
Effect of salinity on rheological and strength properties of cement-stabilized clay minerals
Published in Marine Georesources & Geotechnology, 2020
Jie Yin, Ming-ming Hu, Gui-zhong Xu, Wen-xia Han, Yong-hong Miao
As we know, kaolinite is a layered silicate mineral, with one tetrahedral sheet of silica and one octahedral sheet of alumina. Illite and montmorillonite have the same 2:1 layer with two tetrahedral sheets of silica sandwiching a central octahedral sheet of alumina. The space between the 2:1 sheets for illite is occupied by poorly hydrated potassium cations which are responsible for the absence of swelling. While for montmorillonite the individual crystals are not tightly bound hence water can intervene and cause the clay to swell. For a given water content, strength decreases with respect to the type of clay mineral in the order of kaolinite, illite and montmorillonite (Wanger 2013). Moreover, the cation exchange (CE) is the main source responsible for the change in soil properties with change in salinity and curing. The cation-exchange capacity (CEC) of illite is smaller than that of montmorillonite but higher than that of kaolinite. The salinity is caused by NaCl (sodium cation). The cement stabilizer contains calcium cation. The CEC of sodium cation is smaller than calcium cation. Sodium and chloride have very long residence times, while calcium tends to precipitate much more quickly.