Dissolution of Kestelek's Colemanite Containing Clay Minerals in Water Saturated with Sulfur Dioxide

2002 ◽  
Vol 41 (12) ◽  
pp. 2853-2857 ◽  
Author(s):  
Özkan Küçük ◽  
M. Muhtar Kocakerim ◽  
Ahmet Yartaşı ◽  
Mehmet Çopur
Keyword(s):  
Sulfur Dioxide ◽  
Clay Minerals ◽  
Water Saturated

Swelling clayey soils promote slope instability in the Muhunguzi watershed, western Burundi

2020 ◽  
Author(s):  
Bruno Delvaux ◽  
Clairia Kankurize ◽  
Gervais Rufyikiri
Keyword(s):  
Clay Minerals ◽  
Clay Fraction ◽  
Slope Instability ◽  
Atterberg Limits ◽  
Intense Rainfall ◽  
Angle Of Friction ◽  
Red Soils ◽  
Soil Cohesion ◽  
Internal Angle ◽  
Water Saturated

<p>In Burundi, landslides are frequent on the western slope of the Congo-Nile ridge. Unfortunately, they are poorly studied and understood despite their deadly consequences. Previous reports have suggested that slope steepness, lithology and clay soils expose this slope to landslides, while heavy and intense rainfall is a trigger. However, the role of soil in the vulnerability of this specific slope to landslides is unknown. Here we investigate on soil characteristics involved in land sliding in this area.</p><p>We selected and sampled black and red soils in two Muhunguzi landslides. We determined the soil plasticity from Atterberg limits as well as the particle size distribution. In addition, we measured the soil weathering stage, and further identified the clay minerals from measuring the cation exchange capacity of the clay fraction and analyzing clay samples with X-ray diffraction (XRD).</p><p>Both the black and red soils are moderately weathered since TRB values in the B horizons range between 330 and 425 cmol(+) kg<sup>-1</sup>. The soils are loamy clayey to clayey (% clay: 33-55%), and contain high charge clay minerals. They do not differ in their Atterberg limits, which classify the soils as medium plasticity soils in the Casagrande plasticity diagram. Our data further show that both soils have a medium swelling potential. XRD show that the clay fraction consists of kaolinite and smectite and/or vermiculite. The latter 2:1 clay minerals are expandable and swelling clays, respectively. They give these two soils their plasticity and swelling properties. These two properties play an important role in the mechanical behavior of water-saturated soils. Indeed, swelling reduces soil cohesion while the plasticity index and the liquidity limit vary inversely with the internal angle of friction of the soil; cohesion and internal angle of friction being the fundamental parameters of the soil shear resistance. In addition, the soil mantle covers a hard schistose rock whose declivity is parallel to the soil surface slope. Thus, after intense rainfall during the wet season, the water-saturated soil reaches a level of liquidity sufficient to favor a landslide, all the more easily if the slope of the hard rock is inclined in the direction of the gravity flow.gru</p>

Effects of clay minerals on the transport of nanoplastics through water-saturated porous media

2021 ◽  
pp. 148982
Author(s):  
Taotao Lu ◽  
Benjamin S. Gilfedder ◽  
Hao Peng ◽  
Geng Niu ◽  
Sven Frei
Keyword(s):  
Porous Media ◽  
Clay Minerals ◽  
Saturated Porous Media ◽  
Water Saturated

Elastic moduli of anisotropic clay

Geophysics ◽  
2007 ◽  
Vol 72 (5) ◽  
pp. D107-D117 ◽  
Author(s):  
Irina O. Bayuk ◽  
Mike Ammerman ◽  
Evgeni M. Chesnokov
Keyword(s):  
Clay Minerals ◽  
Effective Medium Theory ◽  
Optimization Technique ◽  
Transversely Isotropic ◽  
Effective Medium ◽  
Stiffness Tensor ◽  
Medium Theory ◽  
Inversion Technique ◽  
Water Saturated

Clay minerals are important components in shales, controlling their elastic properties and anisotropy. The elasticity of crystalline clay minerals differs significantly from that of clay in situ because of the ability of clay particles to bind water. In the ma-jority of published works, only isotropic moduli for in situ clays are reported. However, anisotropy is inherent in the clay elas-ticity. We develop an inversion technique for determination of the stiffness tensor of in situ clay from the shale’s stiffness tensor. As an example, we obtain the stiffness tensor of a “water-clay” composite from the data on the water-saturated Greenhorn shale sample, whose clay composition consists of almost equal amounts of illite and smectite and comparable amounts of kaolinite and chlorite. The stiffness tensor of the water-clay composite is found for the Greenhorn shale with step-by-step inversion based upon an effective medium theory. The inversion usesa nonlinear optimization technique with bounds imposed on the estimated parameters. In the inversion, we apply different approaches of the effective medium theory using a published method referred to here as the generalized singular approxi-mation (GSA). The GSA method makes it possible to take into account the microstructure of shales. The resulting elasticity constants of the anisotropic (transversely isotropic) in situ clay composite are [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text] (in GPa); and the density equals [Formula: see text]. The Thomsen parameters for the clay composite are [Formula: see text], [Formula: see text], and [Formula: see text]. The elasticity constants found for this clay composite can be used in the theoretical analysis of shales that have a similar composition of clay but with different mineral compositions. The inversion technique developed can be used for general shale water-clay composites when the mineral composition and orientation of the clay platelets are known.

Significance of clays in the petroleum geology of the Niger Delta

Clay Minerals ◽  
1982 ◽  
Vol 17 (1) ◽  
pp. 91-103 ◽  
Author(s):  
D. O. Lambert-Aikhionbare ◽  
H. F. Shaw
Keyword(s):  
Clay Minerals ◽  
Niger Delta ◽  
Petroleum Geology ◽  
Burial Diagenesis ◽  
The Poor ◽  
Early Migration ◽  
Engineering Problems ◽  
Reservoir Sandstones ◽  
Water Saturated

AbstractSediments of the Tertiary Akata and Agbada Formations have been studied by mineralogical and petrographic techniques. In the Akata and Agbada shales the clays are largely detrital, with only minimal alteration attributable to the effects of burial diagenesis. Clay minerals occur in minor (<10%) amounts in the reservoir sandstones of the Agbada Formation both as detrital and authigenic phases. There are significant differences between the clay assemblages of the water- and hydrocarbon-bearing sandstones. The latter have lower overall clay contents and authigenic kaolinite, whilst authigenic kaolinite and smectite are present in the water-saturated sandstones. These differences are thought to be related to the early migration of hydrocarbons into the reservoir sands. The causes of the poor degree of cementation in the Agbada sandstones are discussed along with the engineering problems posed by their very friable nature.

An Environmental Wet Cell For High Voltage Electron Microscopy

1973 ◽  
Vol 31 ◽  
pp. 18-19
Author(s):  
N.J. Tighe ◽  
H.M. Flower ◽  
P.R. Swann
Keyword(s):  
Electron Microscopy ◽  
High Temperature ◽  
Image Quality ◽  
Inelastic Scattering ◽  
High Voltage ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
Environmental Cell ◽  
Water Saturated ◽  
High Temperature Gas

A differentially pumped environmental cell has been developed for use in the AEI EM7 million volt microscope. In the initial version the column of gas traversed by the beam was 5.5mm. This permited inclusion of a tilting hot stage in the cell for investigating high temperature gas-specimen reactions. In order to examine specimens in the wet state it was found that a pressure of approximately 400 torr of water saturated helium was needed around the specimen to prevent dehydration. Inelastic scattering by the water resulted in a sharp loss of image quality. Therefore a modified cell with an ‘airgap’ of only 1.5mm has been constructed. The shorter electron path through the gas permits examination of specimens at the necessary pressure of moist helium; the specimen can still be tilted about the side entry rod axis by ±7°C to obtain stereopairs.

Hydrated form of some clay minerals observed using a film sealed environmental cell

1978 ◽  
Vol 36 (1) ◽  
pp. 72-73
Author(s):  
N. Kohyama ◽  
K. Fukushima ◽  
A. Fukami
Keyword(s):  
Clay Minerals ◽  
Morphological Changes ◽  
Carbon Film ◽  
Electron Microscopic Observation ◽  
Adsorbed Water ◽  
Electron Microscopic ◽  
Hydrated Form ◽  
Thin Carbon ◽  
Environmental Cell ◽  
Thin Carbon Film

Since the interlayer or adsorbed water of some clay minerals are quite easily dehydrated in dried air, in vacuum, or at moderate temperatures even in the atmosphere, the hydrated forms have not been observed by a conventional electron microscope(TEM). Recently, specific specimen chambers, “environmental cells(E.C.),” have been developed and confirmed to be effective for electron microscopic observation of wet specimen without dehydration. we observed hydrated forms of some clay minerals and their morphological changes by dehydration using a TEM equipped with an E.C..The E.C., equipped with a single hole copper-microgrid sealed by thin carbon-film, attaches to a TEM(JEM 7A) with an accelerating voltage 100KV and both gas pressure (from 760 Torr to vacuum) and relative humidity can be controlled. The samples collected from various localities in Japan were; tubular halloysite (l0Å) from Gumma Prefecture, sperical halloysite (l0Å) from Tochigi Pref., and intermediate halloysite containing both tubular and spherical types from Fukushima Pref..

Colloidal systems in soils

1994 ◽  
Vol 52 ◽  
pp. 64-65
Author(s):  
J. Thieme ◽  
J. Niemeyer ◽  
P. Guttman
Keyword(s):  
Clay Minerals ◽  
Polymeric Materials ◽  
Spatial Arrangement ◽  
High Specific Surface Area ◽  
Turnover Rates ◽  
Colloidal Systems ◽  
Chemical Conditions ◽  
Aggregation Phenomena ◽  
Iron And Manganese ◽  
Soil Colloids

In soil science the fraction of colloids in soils is understood as particles with diameters smaller than 2μm. Clay minerals, aquoxides of iron and manganese, humic substances, and other polymeric materials are found in this fraction. The spatial arrangement (microstructure) is controlled by the substantial structure of the colloids, by the chemical composition of the soil solution, and by thesoil biota. This microstructure determines among other things the diffusive mass flow within the soils and as a result the availability of substances for chemical and microbiological reactions. The turnover of nutrients, the adsorption of toxicants and the weathering of soil clay minerals are examples of these surface mediated reactions. Due to their high specific surface area, the soil colloids are the most reactive species in this respect. Under the chemical conditions in soils, these minerals are associated in larger aggregates. The accessibility of reactive sites for these reactions on the surface of the colloids is reduced by this aggregation. To determine the turnover rates of chemicals within these aggregates it is highly desirable to visualize directly these aggregation phenomena.

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