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Cliff T. Johnston - One of the best experts on this subject based on the ideXlab platform.

  • Clay Mineral–water interactions
    Developments in Clay Science, 2018
    Co-Authors: Cliff T. Johnston
    Abstract:

    Abstract The interaction of water with Clay Minerals is central to a wide range of disciplines that span from fundamental particles used in materials science and engineering to applied aspects in soil science and geotechnical engineering. Because water is the most abundant molecule on the surface of the Earth, and Clay Minerals are ubiquitous Mineral phases, it follows that Clay–water interactions play many important roles in the biosphere. In fact, water is an integral component of many Clay Mineral structures. This chapter reviews key elements of the structure of water, its interaction with ions, and the interaction of water with Clay Minerals. Surface interactions include hydrogen bonding, ion–dipole, dipole–dipole, and van der Waals interactions involving both neutral and charged Clay Mineral surfaces. Recent spectroscopic and molecular modelling studies of Clay Mineral–water interactions are presented in the framework of molecular probes and reporter groups.

  • Infrared Studies of Clay Mineral-Water Interactions
    Developments in Clay Science, 2017
    Co-Authors: Cliff T. Johnston
    Abstract:

    Abstract Water is an integral part of many Clay Mineral structures and can be found in diverse nano-confined environments. Clay Mineral-water interactions are critically linked to essentially all physical, chemical, and biological aspects of Clay science. Infrared spectroscopy is particularly sensitive to the vibrational bands of both adsorbed H 2 O and structural OH groups. The application of infrared and Raman methods to study Clay Mineral-water interactions have provided chemical insights that include Clay Mineral-swelling, hysteresis, molecular mechanisms of water adsorption, chemical reactivity, cation exchange, hydrophobic/hydrophilic nature of Clay surfaces, and Clay Mineral-organic interactions. Spectroscopic information from Clay Mineral-water studies comes from examining the vibrational changes that occur to H 2 O molecules in close proximity to Clay surfaces, and from spectral changes from structural OH groups of the Clay Mineral that are influenced by changes in water content.

Shuqin Yang - One of the best experts on this subject based on the ideXlab platform.

  • Silylation of Clay Mineral surfaces
    Applied Clay Science, 2013
    Co-Authors: Qi Tao, Jianxi Zhu, Peng Yuan, Wei Shen, Shuqin Yang
    Abstract:

    Abstract Silylation of Clay Mineral surfaces has attracted much attention because silylated products exhibit properties suitable for many applications in materials science and environmental engineering. Successful silylation strongly depends on the reactivity of Clay Mineral surfaces (e.g., density of surface hydroxyl), characteristics of silane (e.g., number of functional group and configuration of silane) and the reaction conditions (e.g., polarity of solvent and reaction temperature). For non-swelling Clay Minerals such as kaolinite, pre-intercalation with small polar molecules is an indispensable step in the silylation of interlayer surfaces. The temperature of the grafting reaction has a significant influence on silane intercalation, and the displacement of pre-intercalated molecules, as well as on the structure of the silylated products. On the other hand, silane is readily intercalated into swelling Clay Minerals such as montmorillonite. The broken edges of 2:1 type Clay Minerals are the most reactive sites for grafting. The polarity of the solvents used is another important factor controlling the extent of grafting, and the basal spacing of the silylated products. Grafting silane during the course of Clay Mineral synthesis (defined as in situ silylation in this review) has proved to be an efficient way of silylating Clay Mineral surfaces.

Hyen-goo Cho - One of the best experts on this subject based on the ideXlab platform.

  • Clay Mineral distribution and provenance in the Heuksan mud belt, Yellow Sea
    Geo-Marine Letters, 2015
    Co-Authors: Hyen-goo Cho, Soon-oh Kim, Kyeong Yoon Kwak, Hunsoo Choi, Boo-keun Khim
    Abstract:

    The Heuksan mud belt (HMB), located in the southeastern Yellow Sea, runs parallel to the southwest coast of Korea. In this study, the distribution and relative contribution of four major Clay Minerals are investigated using 101 surface sediment samples collected in the course of KIOST (2001, 2010, 2011) and KIGAM (2012) cruises, as well as 33 river sediment samples (four from the Huanghe River, three from the Changjiang River, and 26 from Korean rivers) in order to clarify the provenance of fine-grained sediments in the HMB. Based on this currently largest and most robust dataset available for interpretation, the Clay Mineral assemblages of the fine-grained sediments in the HMB are found to be on average composed of 64.7% illite, 17.9% chlorite, 11.4% kaolinite, and 5.9% smectite. Overall, the Clay Mineral assemblages are similar in both the northern and the southern parts of the HMB, although smectite seems to be relatively enriched in the southern part, whereas kaolinite is slightly more dominant in the northern part. This clearly indicates that the Clays are mostly derived from Korean rivers and, in the southern part of the HMB, partly also from the Huanghe River in China. The new data thus confirm and strengthen the tentative interpretation of some earlier work based on a more limited dataset.

  • Clay Mineral Distribution in the Yellow Sea Surface Sediments: Absolute Mineral Composition and Relative Mineral Composition
    Journal of the mineralogical society of Korea, 2008
    Co-Authors: Dong-hyeok Moon, Dong-hyeok Shin, Kyung-hoon Shin, Hyen-goo Cho
    Abstract:

    We studied the difference between the Clay Mineral content in the bulk marine sediments (absolute Clay Mineral composition) and Clay Mineral content only in total Clay Minerals (relative Clay Mineral composition) of the Yellow Sea marine sediments, and correlated the relationship between their distribution patterns. We used 56 Yellow Sea Surface sediments collected at the second cruise in 2001 of KORDI, and determined the absolute Mineral composition using the quantitative X-ray diffraction analysis. Yellow Sea surface sediments consist of primary rock forming Minerals including quartz (average 44.7%), plagioclase (15.9%), alkali feldspar (10.0%), hornblende (2.8%) together with Clay Minerals (illite 15.3%, chlorite 2.6% and kaolinite 1%) and carbonates (calcite 1.7%, aragonite 0.6%). Absolute Clay Mineral contents are very high in the region extending from the southeast of Sandong Peninsula to the southwest of Jeju Island. In contrast, it is very low along the margin of the Yellow Sea. Such distribution patterns of absolute Clay Mineral content are very similar to those of fine-grained sediments in the study area. The average relative Clay Mineral composition of illite, chlorite, and kaolinite is respectively 80.3%, 14.9% and 4.8%. The distribution pattern of relative Mineral composition shows very different phenomenon when compared with those of absolute Mineral composition, and also do not exhibit any positive relationship with that of fine-grained sediments in which Clay Mineral composition is abundant. Therefore, we suggest that the relative Clay Mineral compositions and their distribution patterns must be used very carefully when interpreting the origin of sediment provenance.

Meng Zhu - One of the best experts on this subject based on the ideXlab platform.

Franz X Gingele - One of the best experts on this subject based on the ideXlab platform.

  • Clay Mineral distribution in surface sediments between indonesia and nw australia source and transport by ocean currents
    Marine Geology, 2001
    Co-Authors: Franz X Gingele, Patrick De Deckker, Clausdieter Hillenbrand
    Abstract:

    Abstract The Clay Mineral distribution in sediments between Indonesia and NW Australia has been assessed on the basis of 166 core-top samples. Clay Mineral assemblages are closely related to the geology and weathering regime of the adjacent hinterland and allow the distinction of four Clay Mineral provinces. Three provinces, Western, Central and Eastern Province are situated along the Indonesian Islands Arc, from Sumatra in the west to Timor in the east. Illite is the major Clay Mineral of the Western and eastern Province, whereas the Central Province abounds with smectite. The fourth province comprises the NW and West Australian shelf and slope, as well as offshore plateaus and is dominated by kaolinite. Transport of Clays by surface and subsurface ocean currents can be observed within the provinces, e.g. with the Leeuwin and West Australian Current in the NW Australian Province and with the outflow of low-salinity water through the Sunda and Lombok straits in the Central Province. Transport of Clays across province boundaries is inhibited by strong salinity fronts, with the exception of the boundary between the Central and Eastern Province.

  • Clay Mineral distribution in surface sediments of the south atlantic sources transport and relation to oceanography
    Marine Geology, 1996
    Co-Authors: Rainer Petschick, Gerhard Kuhn, Franz X Gingele
    Abstract:

    Abstract Surface samples, mostly from abyssal sediments of the South Atlantic, from parts of the equatorial Atlantic, and of the Antarctic Ocean, were investigated for Clay content and Clay Mineral composition. Maps of relative Clay Mineral content were compiled, which improve previous maps by showing more details, especially at high latitudes. Large-scale relations regarding the origin and transport paths of detrital Clay are revealed. High smectite concentrations are observed in abyssal regions, primarily derived from southernmost South America and from minor sources in Southwest Africa. Near submarine volcanoes of the Antarctic Ocean (South Sandwich, Bouvet Island) smectite contents exhibit distinct maxima, which is ascribed to the weathering of altered basalts and volcanic glasses. The illite distribution can be subdivided into five major zones including two maxima revealing both South African and Antarctic sources. A particularly high amount of Mg- and Fe-rich illites are observed close to East Antarctica. They are derived from biotite-bearing crystalline rocks and transported to the west by the East Antarctic Coastal Current. Chiorite and well-crystallized dioctaedral illite are typical Minerals enriched within the Subantarctic and Polarfrontal-Zone but of minor importance off East Antarctica. Kaolinite dominates the Clay Mineral assemblage at low latitudes, where the continental source rocks (West Africa, Brazil) are mainly affected by intensive chemical weathering. Surprisingly, a slight increase of kaolinite is observed in the Enderby Basin and near the Filchner-Ronne Ice shelf. The investigated area can be subdivided into ten, large-scale Clay facies zones with characteristic possible source regions and transport paths. Clay Mineral assemblages of the largest part of the South Atlantic, especially of the western basins are dominated by chlorite and illite derived from the Antarctic Peninsula and southernmost South America and supported by advection within the Circumantarctic Deep Water flow. In contrast, the East Antarctic provinces are relatively small. Assemblages of the eastern basins north of 30°S are strongly influenced by African sources, controlled by weathering regimes on land and by a complex interaction of wind, river and deep ocean transport. The strong gradient in Clay Mineral composition at the Brazilian slope indicate a relatively low contribution of tropically derived assemblages to the western basins.