bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanisms Controlling the Permeability of Clays
Authors: Mesri Gholamreza , Olson Roy E. 
Published: August 2006

AbstractCoefficients of permeability, calculated using Terzaghi’s theory of one-dimensional consolidation, are reported for smectite, illite, and kaolinite, in water, methyl and ethyl alcohol, benzene, and carbontetrachloride. When the pore fluid was water the clays were homoionized to either the sodium or calcium form and the pore water electrolyte concentration was varied. The coefficients of permeability are evaluated in terms of both mechanical and physico-chemical variables. It appears that the coefficients of permeability are mainly influenced by mechanical effects, particularly the distribution of void sizes and the tortuosity of the channels. The coefficient of permeability is maximized if the flow channels consist of many small channels and a relatively few large ones, through which the main flow occurs. Physico-chemical variables exert great influence on the coefficient of permeability through their influence on dispersion or aggregation of the clay particles.
Structural Factors Controlling Stacking Sequences in Dioctahedral Micas
Authors: Güven Necip 
Published: August 2006

AbstractDeviations in the symmetry of mica single layers from the ideal arrangement with all atoms in hexagonal arrays are caused by the structural factors such as compositional variation (substitutions), order-disorder, and distortions. The derivative crystal structure theory as applied to mica polymorphism, implies that the ideal symmetry of the mica single layer (C2/m) can be altered to one of its standard subgroups by these structural factors. The “derivative structure” of the single layer may allow a unique interlayer and a specific intralayer configuration and result in a regular stacking sequence.
Erratum to: Scanning electron microscopy of clays and clay minerals
Authors: Bohor B. F. , Hughes R. E. 
Published: August 2006

The author regrets that in the photograph section on p. 50 the caption to the “top” Fig. 2 should read:Fig. 2(b). Rock sample of attapulgite from Yucatan, Mexico (Tertiary).the caption on the “bottom” Fig. 2 should read:Fig. 2(a). Spray-dried attapulgite from Yucatan, Mexico.Also the bar scales on Fig. 9 were inadvertently juxtapositioned:Fig. 9(a) should carry the 10 μL scale, and Fig. 9(b) the 1 μ scale.
Dodecylammonium-Mica Complexes—I Factors Affecting the Exchange Reaction
Authors: Mackintosh E. E. , Lewis D. G. , Greenland D. J. 
Published: August 2006

AbstractDodecylammonium chloride (DAC) is used as a reagent to displace potassium from a wide range of mica minerals. Displacement is rapid and essentially complete for trioctahedral micas even in dilute solutions (0·02N DAC) at low suspension concentrations. Increasing the suspension concentration, or the concentration of potassium in the extracting solution decreased the extent to which potassium could be displaced before equilibrium was established. Under standardized conditions of temperature and suspension concentration, the rate of potassium displacement increased as the particle size decreased although complete displacement was more difficult to achieve for the finest fraction (< 2μ) than for the coarser particles.The trioctahedral samples were shown to be more susceptible to potassium depletion by DAC than dioctahedral material. Within the range of trioctahedral samples examined the rate of reaction was found to be closely related to the fluorine content of the sample. Data obtained for the more resistant dioctahedral specimens was not sufficiently detailed to enable any similar relation to be established.
Transformation of Sericite into an Interstratified Mineral
Authors: Tomita Katsutoshi , Sudo Toshio 
Published: August 2006

AbstractSericite was K-depleted with molten LiNO3. The sample was changed into an interstratified structure in the presence of a small amount of LiNO3 after prolonged treatment, and in the presence of a considerable amount of LiNO3 a similar structure was formed after about 3 hr of reaction. In the case of the presence of the proper amount of NaCl, a mixed-layer structure was easily obtained by treatment for a long period of time with a considerable amount of molten LiNO3.The interstratified mineral had a basal spacing of 22 Å–23·3 Å which was expanded to 25 Å–27·6 Å by treatment with ethylene glycol.
Particle Geometry and Optical Density of Clay Suspensions
Authors: Lahav N. 
Published: August 2006

AbstractData on montmorillonite and illite collected by A. Kahn were further analyzed to show the relationship between particle geometry and the optical density (OD) of the clay suspensions. A correction was introduced to the calculations of the minor dimension of the montmorillonite particles which took into account the volume of water between unit layers.The assumption of disc geometry which was used by A. Kahn in the calculations of the clay particle dimension was found to be consistent with his OD measurements, thus showing that optical measurements can be used to find an equivalent radius of montmorillonite and illite when the general geometry of the particles is the same.
Surface Charge Characterization of Layer Silicates by Competitive Adsorption of Two Organic Divalent Cations
Authors: Philen O. D. , Weed S. B. , Weber J. B. 
Published: August 2006

AbstractDiquat2+ (1, 1’-ethylene-2, 2’-dipyridinium ion) and paraquat2+ (1, 1’-dimethyl-4, 4’-di-pyridinium ion) were competitively adsorbed by Na-saturated kaolinites, smectites and expanded and collapsed vermiculites. The relative preference for one or the other cation varied with the surface charge densities of the adsorbents and the location of the adsorption site, i.e. internal or external. Minerals with high surface charge exhibited preference for diquat whereas minerals with low surface charge preferred paraquat. Expanded vermiculites preferentially adsorbed diquat on internal surfaces. Collapsed vermiculites generally showed a preference for paraquat. Smectites and kaolinites preferentially adsorbed paraquat.Surface charge densities of the layer silicates vs. the relative preference for diquat revealed two linear relationships, one for internal adsorption and one for external adsorption. Internal adsorption was characterized by a strong preference for paraquat on low-charged smectites, a relative decreasing preference for paraquat with higher-charged smectites, and a strong preference for diquat on high-charged expanded vermiculites.Preferential adsorption for paraquat by kaolinite was quite similar to adsorption of paraquat on the external sites of vermiculites. There was no apparent relationship between competitive adsorption and surface charge density of kaolinite.
Sodium-Lithium Exchange Equilibria on Vermiculite at 25° and 50°C
Authors: Gast R. G. , Klobe W. D. 
Published: August 2006

AbstractSodium-lithium exchange equilibria between dilute aqueous chloride solutions and 0.2–62 μ Transvaal, South African vermiculite were studied at 25° and 50°C using a dialysis technique. The K content of the vermiculite was reduced to < 1% of the exchange capacity of 2·14 me/g by exhaustive extraction using Na-tetraphenylboron. The thermodynamic equilibrium constants and in turn the standard free energies and heats of exchange were evaluated from the equilibrium selectivity coefficients at the two temperatures. The standard entropy of exchange, ΔS°, was calculated according to the relationship ΔG° = ΔH° − TΔS°. Similar results were obtained for Na → Li and Li → Na exchange at 25°C, thus confirming the reversibility of the reaction.Sodium preference increased with Na saturation of the vermiculite and equilibrium selectivity coefficients ranged from 6·0 to 22·0 at 25°C. In comparison, selectivity coefficients for Na-Li exchange on montmorillonite ranged from 1·0 to 2·0 and became smaller with increasing Na saturation. The standard free energy and heat of exchange on vermiculite at 25°C were −1444 and −5525 cal mole−1, respectively, resulting in a ΔS° value of −13·7 e.u. This relatively large entropy change is probably due to differences in ion hydration in the solution and surface phases.
Reactivity of Clay Minerals With Acids and Alkalies
Authors: Carroll Dorothy , Starkey Harry C. 
Published: August 2006

AbstractOne-g samples of a montmorillonite, a metabentonite, an illite, two kaolinites, and three halloysites were treated with 50 ml of hydrochloric acid (6·45 N, 1: 1), acetic acid (4·5 N, 1: 3), sodium hydroxide (2·8N), sodium chloride solution (pH 6·10; Na = 35‰; Cl = 21·5‰), and natural sea water (pH 7·85; Na = 35·5‰; Cl = 21·5‰) for a 10-day period in stoppered plastic vials. The supernatant solutions were removed from the clay minerals and analyzed for SiO2, Al2O3, CaO, MgO, Na2O, and K2O. All the solutions removed some SiO2, Al2O3, and Fe2O3 from the samples, but the quantities were small. Sodium hydroxide attacked the kaolin group minerals more strongly than it did montmorillonite, metabentonite, or illite. Halloysite was more strongly attacked by hydrochloric acid than was any of the other experimental minerals. Hydrochloric acid removed iron oxide coatings from soil clay minerals, but acetic acid did not remove them completely. The samples most strongly attacked by HCl and NaOH were examined by X-ray diffraction. Acid treatment did not destroy the structure of the clays, but the halloysite structure was partially destroyed. Sodium hydroxide attacked the halloysite structure, as shown by chemical analysis and X-ray diffraction. These experiments show that treatment in dilute acids has no harmful effect in the preparation of clays for X-ray diffraction. Acetic acid is preferred to hydrochloric acid for this purpose. Hydrochloric acid cleans clay minerals by removing free iron oxide from the surface; acetic acid is less effective.
Clay Mineral Formation In A Deeply Weathered Boulder Conglomerate In North-East Scotland
Authors: Wilson M. J. , Bain D. C. , McHardy W. J. 
Published: August 2006

AbstractThe clay minerals formed in a deeply weathered boulder conglomerate of Middle Old Red Sandstone (Devonian) age in north-east Scotland have been studied by a variety of physical and chemical techniques. The granite and granulite boulders in this deposit are completely weathered. With the exception of microcline, all the feldspars in these rocks—orthoclase feldspar, orthoclase-microperthite, albite, and oligoclase—weather to a Cheto-type montmorillonite, poor in iron. Electron and optical microscopy indicate that the weathering transformation is a direct one, without the intervention of any intermediate crystalline or well-defined amorphous phase. Structural control of the primary mineral over the formation of the montmorillonite seems to have been a minimal factor and the evidence suggests that the clay mineral crystallized from the soluble or colloidal products arising from the decomposed feldspars. Smaller amounts of kaolinite also formed during weathering but largely from the weathering of muscovite. The environment in which these changes occurred seems to have been alkaline in a relatively closed system. Chemical analyses of related cores and weathered shells of granite and granulite bounders show only a slight decrease of silica and an increase in magnesia. Judging from the extent of alteration to secondary clay minerals, the order of resistance towards weathering of the primary minerals in these rocks is plagioclase = orthoclase < muscovite < biotite < microcline < quartz.
Fabric of Kaolinite and Illite Floccules
Authors: O’Brien Neal R. 
Published: August 2006

AbstractA scanning and high voltage electron microscope study of the fabric of laboratory sedimented moist uncompressed kaolinite and illite floccules reveals an abundance of face-face flake orientation in the porous clay network. Clays were flocculated in the laboratory in both distilled water and slightly saline (1 g/l. NaCl) water using various clay concentrations. Floccules taken from the moist clay mass were prepared for study by freeze-drying and impregnation with polyethylene glycol.There is little difference in the fabric of kaolinite flocculated in distilled or slightly saline water. The fabric is dominated by a 3-dimensional network of twisted chains of face-face oriented flakes having the appearance of a stair-stepped cardhouse. Illite floccules in distilled water also consist of abundant face-face oriented overlapping flakes. However, in salt water there is a more even mixture of fabrics—edge-to-face flocculation of individual platelets and also stepped clusters of face-to-face oriented flakes, the latter being more abundant.It is suggested that under the experimental conditions the double layer of each clay particle is compressed resulting in an increase in the importance of van der Waals forces of attraction. As a result flakes approach each other and rotate into a parallel or subparallel position. The resultant dominant fabric is that of a stepped cluster of overlapping flakes.
Clay Mineral Formation in an Alpine Environment
Authors: Reynolds Robert C. 
Published: August 2006

AbstractVermiculite, mixed-layer vermiculite-phlogopite, and smectite are presently forming from igneous and metamorphic bedrock in the alpine zone of the northern Cascades, Washington. In addition, south-facing exposures of quartz-diorites and metadiorites above snow line are weathering to ferruginous bauxite. Calculations indicate that vermiculite is presently forming from phlogopite schists in this environment at a unit area rate that is approximately six times the average estimated rate of clay erosion for North America. The mineralogical data indicate that chemical weathering in this region is a quantitatively significant process, and suggest that in the development of current geomorphic concepts researchers may have generally underestimated the importance of chemical weathering in alpine environments.
Mechanisms of Formation of Colored Clay-Organic Complexes. A Review
Authors: Theng B. K. G. 
Published: August 2006

AbstractThe interactions of clay minerals with organic compounds which give rise to the formation of colored complexes, are discussed. The color reactions of clays can be ascribed to a charge transfer between the mineral and the adsorbed species. The active sites on the clay are aluminums exposed at crystal edges and/or transition metal cations in the higher valency state at planar surfaces both of which can act as electron acceptors. The pH of the system, the nature of the solvent and that of the exchangeable cation, influence the rate of color development and the final intensity and quality of the color produced. Steric factors also play a part in reactions involving bulky organics. Some practical applications based on color reactions of clays with electron-donating organic substances are described.
Acid Character of Sauconite: Increase in Cation Exchange Capacity on Aging in Water and the Role of Zn2+ and Al3+ Ions
Authors: Mitra R. P. , Sindhu P. S. 
Published: August 2006

AbstractpH- and conductometric titration curves of acid sauconite, freshly prepared by the action of H-resin on sauconite showed four segments, each, where H+, Al3+ and Zn2+ ions and a weak acid reacted with the added base in the sequence mentioned. The H+, Al3+ and Zn2+ ions, but not the weak acid, could be exchanged for the cations of a neutral salt. The exchangeable Al3+ and Zn2+ ions were derived from the lateral surfaces by the action of the H-resin. When the acid sauconite was allowed to age in water, the exchangeable H+ and Al3+ ions were gradually replaced by Zn2+ ions giving, finally, a Zn-clay. The pH rose from 4·2 to 6·3 and the total amount of exchangeable cations increased as aging proceeded. When the Zn-clay was formed, the increase in cation exchange capacity was about 70 per cent. Octahedral Al at the edges, carrying positive charges, were discharged by hydrolysis during the aging, causing the net negative charge and, hence, cation exchange capacity, to increase. Aging had little effect on the amount of the weak acid. Zn and Al ions at the edges exhibited the weak acid function. Only edge-Zn was active in the fully aged clay.
Preparation and Solvation Properties of Some Variable Charge Montmorillonites
Authors: Brindley G. W. , Ertem Gözen 
Published: August 2006

AbstractLi-, Na-, K- and Ca-saturated Wyoming montmorillonites have been prepared and used to obtain Li,Na-, Li,K-, and Li,Ca-montmorillonites with a range of Li contents. These were heated at 220°C for 24 hr, causing the Li+ ions to migrate mainly into the layer structure and leaving varying amounts of Li+, Na+, K+, and Ca2+ ions in the interlayer positions as determined by exchange with NH4+ ions. The results are only partially consistent with a migration of the Li+ ions into vacant octahedral sites up to the limit of the octahedral layer charge. Solvation of the resulting clays with water and various organic liquids showed the following results: With water, acetone and 3-pentanone, expansion of the montmorillonites increased in a step-wise manner with increasing numbers of interlayer cations qualitatively in accord with the field strength of the cations and the dipole moments of the molecules. With ethanol, ethylene glycol and morpholine, swelling with each liquid was practically independent of the number of interlayer cations, within the limits of the prepared materials. It is suggested that for the second group of liquids some mechanism additional to cation-dipole interactions, such as hydrogen bonding to silicate oxygen surfaces, may play an important part.
Effects of Octahedral-Iron Reduction and Swelling Pressure on Interlayer Distances in Na-Nontronite
Authors: Wu Jun , Low P. F. , Roth C. B. 
Published: August 2006

AbstractA new type of environmental chamber for X-ray diffraction was designed that could sustain elevated, internal pressures of nitrogen or any other gas under oxygen-free conditions and that allowed the positions of the specimen and edge aperture to be adjusted by remote control. It was used to determine the values of the interlayer spacing, λ, of nontronite from Garfield, Washington, in different stages of reduction at different values of Π, the swelling pressure of the nontronite. At equilibrium, Π was equal to the pressure under which water was expressed from the clay. Both partially and fully expanded layers were found to exist in the reduced nontronite, the fraction of partially expanded layers increasing with increasing Π and Fe2+/Fe3+, the ratio of Fe2+ to Fe3+ in octahedral sites. Also, λ for the partially expanded layers was found to depend on Fe2+/Fe3+ but not on Π, and λ for the fully expanded layers was found to depend on Π but not on Fe2+/Fe3+. These findings were interpreted to mean that the reduction of Fe affected the short-range interlayer forces, but not the long-range ones.
Clay-Organic Complexes as a Cementing Agent in the Arahama Sand Dune, Japan
Authors: Tazaki Kazue , Kimura S. , Yoshimura T. , Akai J. , Fyfe W. S. 
Published: August 2006

AbstractCementing materials in the Arahama sand dune, Japan, were studied mineralogically and biogeochemically to gain a better understanding of the cause of hardening. The cementing material is a clay-organic complex composed of noncrystalline gels and a matrix of small, poorly crystalline particles showing 14–16-Å spacings. The gel materials appear to have transformed into the poorly crystalline particles, which have a high carbon content and Al/Si ratios of 2.2 to 2.0. These particles are slightly richer in Si and poorer in Fe than the gel materials themselves. The organic portion of the complex can be removed by H2O2 treatment, leaving a noncrystalline network-structure containing a dispersed granular component. Scanning auger-depth profiles of individual particles show a high surface concentration of C and O and an increase in the Al/Si ratio with depth. The energy-intensity distribution suggests a mixture of carbon compounds having a major core-line binding energy of a hydrocarbon. The gel-cementing materials in the sand dune may have been formed from biochemical weathering products of organic matter, which subsequently controlled the formation of clay-organic complexes.
Phillipsite from Silicic Tuffs in Saline, Alkaline-Lake Deposits
Authors: Sheppard Richard A. , Fitzpatrick Joan J. 
Published: August 2006

AbstractPhillipsite is a common constituent in diagenetically altered rhyolitic vitric tuffs of Cenozoic saline, alkaline-lake deposits where it occurs as spherulites or aggregates of prismatic crystals. This phillipsite has chemical and physical properties that differ from phillipsites that occur in rocks of other compositions and depositional environments, but previously it had not been completely characterized. Published analyses of five samples from four deposits in the southwestern United States show that the phillipsite is very siliceous and alkalic; the Si/(Al + Fe3+) ratio is 3.08–3.37, alkalis greatly exceed the divalent exchangeable cations, and the Na/K ratio is 1.05–3.05. The mean index of refraction (1.451–1.470) is much lower than that generally reported for the phillipsite group and can be correlated with the relatively high Si and alkali contents. Monoclinic unit-cell parameters show the following ranges: a = 9.931–9.991 Å, b = 14.142–14.155 Å, c = 8.650–8.706 Å, ß = 124.57–125.07°, and V = 1000.3–1007.4 Å3. The especially small b dimension is consistent with the high Si content.
Rheological Properties of Organophilic Synthetic Hectorites and Saponites
Authors: Iwasaki Takashi , Onodera Yoshio , Torii Kazuo 
Published: August 2006

AbstractTo determine the dependency of rheological properties on mineralogical characteristics, eleven organophilic hectorite and nine organophilic saponite samples were prepared from hydrothermally synthesized smectites and a quaternary ammonium salt containing mainly octadecyl groups as alkyl chains and were examined by X-ray powder diffraction (XRD), particle size, chemical, and rheological procedures. The rheological properties of the organophilic products dispersed in toluene were found to depend chiefly on (1) particle size, (2) the expansion behavior of the stacked clay platelets, in which the amount and location of negative charge of the silicate layer affected the expandability, and (3) the amount of methanol added as a polar activator. By the addition of 2–4% methanol, apparent viscosities of the hectorite clays were drastically increased at low shear rate, although even a 10% addition did not significantly affect the saponite clays. Under the most suitable gellation conditions, the saponite clays showed lower apparent viscosity than the hectorite clays. Inasmuch as the former had its negative charge near the surface of the silicate layer and formed strong bonds to the organic ion, the expansion of the platelets was apparently difficult. An optimum layer charge for increasing the viscosity was found; specifically 0.45–0.50 and 0.50–0.55 equivalents per half unit cell for saponite and hectorite clays, respectively. Because the saponite clays contained a denser population of organic ions than the hectorite clays, the ion density in the interlayer of both clays was considered to be the same, i.e., about 0.4 organic ions per unit ab area.