bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Structural Status of Clay Systems
Authors: Aylmore L. A. G. , Quirk J. P. 
Published: August 2006

AbstractIllite and montmorillonite have been compressed into cores under a pressure of 1200 atm. The structural status of these clays has been examined by means of detailed nitrogen adsorption-desorption isotherms and by means of electron micrographs of fracture surfaces of the clay cores. The subsequent swelling behavior of sodium and calcium clay cores has been analyzed in terms of the model derived from these measurements and the specific surface area of the clay. A generalized theory for the condensation of plate-shaped particles into domains has been proposed.Measurements of the effect of electrolyte concentration and hydrostatic suction on the swelling of sodium- and calcium-saturated clay cores indicate that diffuse double layer theory may play a significant part in determining the swelling of monovalent clay systems but not divalent clay systems.The magnitude of the film thicknesses apparently developed in solutions as concentrated as molar and 4 M, where the condition of ideal solutions required by diffuse double layer theory is certainly not fulfilled, seems to indicate that solution uptake is increased by a relaxation of structural strains within the clay matrix on lubrication by solutions. These strains may arise from the distortion of crystals in packing during the drying process. Such relaxations which appear to occur between p F 4 and 3 could initiate the development of a gel structure.
The Flow of Salt Solutions Through Compacted Clay
Authors: McKelvey J. G. , Milne I. H. 
Published: August 2006

AbstractExperimental evidence of the salt filtering ability of compacted bentonite and clay material is presented. Apparatus has been developed in which samples of semi-dry powdered bentonite and shale are compacted under pressures of 10,000 psi and subjected to flow with sodium chloride solutions under fluid pressures up to 10,000 psi. Porosities of 34–41 percent have been obtained with the bentonite and 24 percent with the shale. Permeabilities of 10−5 to 10−6 millidarcies have been measured. A ratio of input to output solution concentration as high as 8 has been found with the bentonite samples and dilute (0.164 N) NaCl solutions. The ratio falls off with increased input concentration and with increased porosity. The shale sample has given a ratio of 1.7 with an input concentration of 0.129 N NaCl.Streaming potential differentials of approximately 1 mV per 100 psi have been measured during the flow experiments. The potential differential is highest with the shale material and shows a decrease with increasing salt concentration.
Anion Influence on Some Soil Physical Properties
Authors: Krebs R. D. , Thomas G. W. , Moore J. E. 
Published: August 2006

AbstractAddition of HCl, H2SO4, and H3PO4 to montmorillonite clay and a montmorillonitic soil had little effect on the liquid limit of these materials over a wide range of concentrations. The liquid limit of a kaolinitic soil clay was reduced markedly by both HCl and H2SO4, whereas H3PO4 decreased the liquid limit value at lower concentrations and increased it at higher ones. These results are discussed in light of the charge variability and of anion retention by the kaolinitic soil.
Theory of Flocculation, Subsidence and Refiltration Rates of Colloidal Dispersions Flocculated by Polyelectrolytes
Authors: La Mer Victor K. , Smellie Robert H. 
Published: August 2006

AbstractThe flocculation and subsequent subsidence of colloidal suspensions are markedly increased by the addition of flocculating agents; for example various starches and recently developed synthetic polymers.The rate of flocculation depends not only upon the extent of adsorption of the agent (flocculant) but also upon the order of mixing and the character and extent of the subsequent agitation which determines the character of the floc formed. Electrolytes flocculate by reducing the electrostatic repulsions between charged particles, but long chain polymers produce flocs by a bridging mechanism which overcomes electrostatic repulsions.Quantitative relationships are developed between the optimum concentration of flocculant and the rates of flocculation, subsidence, and particularly rate of filtration through the filter cake.
Hydrothermal Regularly Interstratified Chlorite-Vermiculite and Tobermorite in Alteration Zones at Goldfield, Nevada
Authors: Harvey Richard D. , Beck Carl W. 
Published: August 2006

AbstractHydrothermal alteration of andesitic and dacitic rocks in the Goldfield District, Nevada, has produced regularly interstratified chlorite-vermiculite and tobermorite. X-ray diffraction and oscillating-heating data indicate the regular interstratification of the chlorite-vermiculite. This mineral is found in the zone of least alteration and was formed by the alteration of hornblende phenocrysts. Penninite is an intermediate stage in this reaction. Increased intensity of alteration resulted in the disappearance of chlorite-vermiculite and the development of montmorillonite. Tobermorite, found only in the dacite, is associated with alunite as pseudomorphs after plagioclase phenocrysts in the most intense zone of alteration. The intermediate stage of hydration for tobermorite is indicated by the 11 Å spacing of the 002 diffraction peak. Oscillating-heating X-ray data at atmospheric pressure show that tobermorite decomposes thermally in two stages. The (00l) planes collapse at approximately 520 °C and crystal planes having an 8 Å periodicity collapse at about 760 °C. Wollastonite develops from tobermorite above 700 °C under static heating conditions.
Clay Minerals in Rocks of the Lower Part of the Oquirrh Formation, Utah
Authors: Tooker E. W. 
Published: August 2006

AbstractAn association between clay minerals and rock type is recognized in the rocks of an interlayered sequence of fossiliferous shaly, sandy bioclastic, and cherty limestone, dolomitic limestone, calcareous and dolomitic quartzite, and quartzite that form a portion of the lower part (Pennsylvanian age) of the Oquirrh formation in the northern Oquirrh Range, Utah. These sedimentary rocks are largely of clastic origin and range from fine- to coarse-grained. In part they are cross-bedded, and fossils are locally abundant. Calcite-rich rocks predominate (78 percent) over dolomite- and quartz-rich rocks (17 and 5 percent, respectively). Clay minerals constitute less than one percent in quartzite and range from one to five percent in some limestones.Clay minerals and rock types are commonly observed in the following associations: Illite and chlorite occur in limestone; illite, chlorite, and mixed-layer clay occur in cherty, bioclastic, and sandy limestone and in calcareous quartzite; chlorite and illite commonly are present in dolomitic quartzite; chlorite, illite, and mixed-layer clay are found in dolomitic limestone; and kaolinite, illite and chlorite are typically present in quartzite. The mixed-layer clay has a lattice spacing of 29.4 Å that expands to 31.0 Å when glycolated and contracts irregularly to 13.2 Å when heated to 500 °C; the clay is assumed to consist of 14 Å chloritic and 15 Å montmorillonitic material. Chlorite or mixed-layer clay, or both, generally are associated with rocks containing dolomite.
Dehydration of Fully Hydrated Halloysite from Lawrence County, Indiana
Authors: Harrison Jack L. , Greenberg Seymour S. 
Published: August 2006

AbstractThe changes occurring in fully hydrated halloysite during dehydration have been studied by X-ray diffraction at relative humidities that ranged from 0 to 100 percent. From the results of this study it has been concluded that: (1) layers dehydrate randomly, but instantaneously; (2) the diffraction from an individual crystallite is governed by the ratio of hydrated to dehydrated layers present; and (3) halloysite dehydrated to any degree shows no detectable rehydration when exposed to 100 percent relative humidity for 2 months.
Mineralogical Problems of Intermediate Clay Minerals
Authors: Sudo Toshio , Hayashi Hisato , Shimoda Susumu 
Published: August 2006

AbstractOn the basis of mineralogical studies on many kinds of clay minerals found in Japan, the writers attach great importance to subtle variations in clay minerals and discuss them in the light of the concept of intermediate minerals. An intermediate mineral behaves partly as one mineral (say A) with certain treatments, and as mineral B under other conditions. There are two types of intermediate minerals: the deviation type and the mixed-layer type. The deviation type is homogeneous enough in its structure that we can describe it as composed of a combination of clearly different layer groups. The mixed-layer type has an interstratified structure of two or more kinds of layers. Furthermore it is suggested that each component layer of the mixed-layer type, in general, shows the properties of the deviation type. As an example of a mineral that can be discussed in light of the intermediate mineral concept, the writers describe the properties of very complex mixed-layer minerals related to mica clay minerals associated with epithermal ore deposits in Japan. Normally the mixed-layer minerals are found where there has been successive attack under different conditions of chemical environment or in an area that is transitional between two different chemical environments.Intermediate minerals in general are considered to be a mineral state (mineral configuration) modified in various degrees from an original mineral in response to successive changes of environmental conditions. The above viewpoints are supported by study of many clay specimens collected from alteration zones of epithermal ore deposits in Japan.It is considered that formation of intermediate minerals may be originated because of a latent defect structure in the original mineral. Polar character that is due to unequal distribution or ratio of the tetrahedral cations in a silicate layer may be favorable for the formation of the regular mixed-layer structure. Finally, intermediate minerals may be arranged according to the following scheme: Mineral A—deviation type of mineral A—mixed-layer mineral A-B—deviation type of mineral B—mineral B.
The Specific Sorption of Cobalt and Zinc by Layer Silicates
Authors: Tiller Kevin G. , Hodgson J. F. 
Published: August 2006

AbstractThe sorption of Co and Zn by layer silicates was studied in dilute mineral suspensions containing, in most cases, about 10-6 M Co or Zn. Electrostatic adsorption was eliminated by the presence of 0.1 N CaCl2. Co and Zn were determined by a radioisotopie technique.Detailed studies on montmorillonite and to a lesser extent vermiculite, muscovite and biotite revealed the presence of at least two forms of specifically sorbed Co, one of which was exchangeable by certain ions such as Cu, Ni, Zn, Fe, Mn or more Co and the other, occurring in much smaller amounts, was not exchangeable by these cations. The latter form is considered to result from lattice penetration; the former is associated with surface groups. These forms may be separated quantitatively by several desorption procedures including successive extractions with dilute acetic acid.The total amount and relative proportion of these forms of sorbed Co and Zn depend on the pH of the system, time of reaction, mineral species used, and amount of Co or Zn added. Equilibrium is not readily attained but tends to approach a slow steady state after several days. Isotherms indicate a variation in bonding energy with surface coverage. The sorption of Co and Zn from dilute solutions by any mineral is related to its stability.These studies, considered in conjunction with published data, suggest that a common mechanism may be involved in the specific sorption of many heavy metal cations by many minerals.
The Location of Bound Cobalt on 2:1 Layer Silicates
Authors: Hodgson J. F. , Tiller Kevin G. 
Published: August 2006

AbstractThree techniques have been used to determine what clay mineral surfaces are involved in the selective bonding of Co: (a) polyphosphate ions were used to block edge surfaces of montmorillonite and vermiculite from Co, (b) collapse of the interlamellar spaces with potassium saturation was used to block internal basal surfaces of vermiculite from Co, and (c) autoradiographs were prepared of vermiculite and mica particles that had reacted with Co58. In each case Co in low concentration was allowed to combine with the mineral in the presence of high concentrations of CaCl2.The preliminary sorption of polyphosphate ions had no appreciable effect on the sorption of Co by the minerals studied, indicating that the edge surfaces were not likely to be involved in the Co reaction. The blocking of internal basal areas had only a very slight effect suggesting that these surfaces were involved in the sorption of Co, but only to a limited extent. Autoradiographs of naturally occurring vermiculite particles revealed a somewhat uneven distribution of Co over the planar surface of the particles. Removal of the outer layers of the crystals, either before or after the material had combined with Co but before autoradiography, resulted in a concentration of the metal along edges and cracks.Apparently the external basal surfaces are principally involved in the specific sorption of Co by layer silicates. It is suggested that chemical weathering and physical abrasion of the surfaces introduce defect structures which favor the chemical bonding of heavy metals.
Measurement of Thickness of Dispersed Clay Flakes with the Electron Microscope
Authors: Weir A. H. , Nixon H. L. , Woods R. D. 
Published: August 2006

AbstractThe shadow lengths of dispersed flakes of the layer-lattice mineral, allevardite, were measured with the electron microscope. Details of the experimental technique are given, and the importance of using samples free from very small material is stressed. Measurements of flake thickness made in this way agree well with estimates of the basal spacing of the collapsed lattice obtained from X-ray diffraction, and dispersion of allevardite was found to produce suspended flakes 19 Å thick, corresponding in thickness to the basic structural unit of two 2:1 layers.
Adsorption of 1-n-Alkyl Pyridinium Bromides by Montmorillonite
Authors: Greenland D. J. , Quirk J. P. 
Published: August 2006

AbstractAdsorption isotherms of 1-n-alkyl pyridinium bromides on Na-montmorillomte, and in addition of cetyl pyridinium bromide on Ca-montmorillonite, have been determined. For up to eight carbon atoms in the alkyl chain adsorption has a limit close to the exchange capacity of the clay. With larger ions adsorption occurs beyond this and is accompanied by adsorption of the bromide ion. Adsorption of the cetyl pyridinium ion beyond the exchange capacity is greater on Na- than on Ca-montmorillonite. Replacement of the cation initially present is incomplete. X-ray diffraction analysis shows that the adsorbed ions normally lie flat on the clay surface, but cetyl pyridinium ions may stand up in a plane at right angles to the surface. Interlamellar separations somewhat less than the minimum molecular thicknesses, found for the methyl and ethyl pyridinium ions, are attributed to a combination of (1) “keying” of the alkyl groups into the clay surface, and (2) the effect of the attractive forces between the clay and the pyridinium ring. It is concluded that adsorption is due to ionic and dispersion forces between the pyridinium ions and the clay. For the cetyl compound the dispersion forces are larger than ionic forces. The exchangeable cation initially present influences the adsorption by its effect on the exchange reaction and probably also by its influence on the domain structure of the clay and hence the accessibility of external surfaces of the crystallites.
Adsorption of Hydrolyzed Polyacrylonitrile on Kaolinite
Authors: Mortensen J. L. 
Published: August 2006

AbstractAdsorption experiments were conducted by mixing homoionic kaolinite and C14-labeled hydrolyzed polyacrylonitrile (HPAN) in water and solutions of electrolytes. Langmuir type adsorption isotherms resulted. Exchange cations on kaolinite increased adsorption in approximately the same order as such cations reduce zeta potential, i.e. Th4+ > Ca2+ > Ba2+ > H+ > NH4+ > K+ > Na+. The anomalous increase in adsorption in the presence of polyvalent exchange cations suggested adsorption at the site of base exchange salt formation. Sorbed anions increased adsorption of HPAN in the order of electronegativity, i.e. F- > OH- > H2PO4- > Cl- > CH3COO- > NO3-.An increase in the concentration of electrolyte and acidity of the adsorbate medium increased adsorption of HPAN. This effect was apparently due to the reduction of electrostatic repulsion between HPAN and kaolinite and a reduction in size of the polymer coil. Divalent cations, especially the transition metals capable of being complexed by HPAN, were more effective than univalent cations. Dissolution of the clay lattice caused desorption of HPAN.HPAN adsorption reduced the intensity of the OH and O—Al—OH bands in infrared absorption spectra of the kaolinite. Preadsorption of aurintricarboxylic acid blocked adsorption of HPAN, suggesting that “positive spots” due to exposed lattice aluminum on edges of the clay platelets were adsorption sites.
Swelling of Some Vermiculite-Organic Complexes in Water
Authors: Garrett W. G. , Walker G. F. 
Published: August 2006

AbstractComplexes formed by macroscopic vermiculite crystals and n-alkylammonium ions with alkyl chains of 3‐4 carbon atoms swell unidimensionally in water until the silicate layers are several hundred Ångströms apart.The initiation of swelling is thought to involve the development of “icebergs” of the Frank-Evans type around the alkylammonium ions. Hydration of the oxygen surfaces of the silicate layers may also be a significant factor in the swelling process.Cataphoresis experiments on finely dispersed aqueous suspensions indicate the presence of diffuse double layers of positive ions around negatively charged silicate particles. Further swelling on applying an electric field to individual swollen crystals immersed in water and dilute solutions also has been observed.
Viscosimetric Constants of Suspensions of Clay-Polymer Complexes
Authors: van der Watt H. v. H. , Bodman G. B. 
Published: August 2006

AbstractThe viscosimetric constants of aqueous suspensions of certain homoionic forms of mont-morillonite and attapulgite were measured following adsorption of different kinds and quantities of organic polymers. Dissymmetry and interaction of the clay—organic complexes were then calculated from the Schulz-Blaschke equation and their structures deduced.A positive, linear relationship was found between the dissymmetry of H- and Al-montmorillonite, respectively, and the amount of vinyl acetate maleic anhydride (VAMA) adsorbed-H-montmorillonite displayed the greater dissymmetry and it is inferred that H-montmoril. lonite complexes consist of an edge-to-edge linkage of clay particles through lattice-aluminumcarboxyl bonds. Al-montmorillonite permits three kinds of linkage: edge-to-edge (as with H-montmorillonite), external flat surface-to-surface (producing a “stacked” structure), and surface-to-edge, the last two involving exchangeable aluminum-carboxyl bonds. Edge-to-edge linkages probably predominate.Ca-montmorillonite is unaffected by less than 8 parts of VAMA per thousand of clay. Edge-to-edge linked clay particles appear at this ratio and interaction diminishes. Delayed structural organization can be explained by low polymer adsorption at high initial pH. Maximum dissymmetry of H-montmorillonite-VAMA complexes occurred after titration with NaOH to pH between 6 and 8, above which mutual repulsion between highly dissociated polymer and clay may restrict linkage.H-attapulgite—VAMA complexes are dissymmetrical for low VAMA adsorption but increased adsorption reduces dissymmetry and bundles of edge-to-edge linked particles are formed.Probable structures of montmorillonite complexes with other polymers are also discussed.
A Random Intergrowth of Sepiolite and Attapulgite
Authors: Martin Vivaldi Juan L. , Linares Gonzalez Jose 
Published: August 2006

AbstractThe smectic clays from Cabo de Gata region, Almeria, Spain, are composed mainly of montmorillonite, but they contain appreciable quantities of fibrous clay minerals, some of which are of the palygorskite type. However, there also is a mineral that has properties intermediate between those of palygorskite and sepiolite. Its structure seems to be a random intergrowth of both.
The Geology of Vermiculite Occurrences
Authors: Bassett William A. 
Published: August 2006

AbstractVermiculite occurrences can be divided into two major categories, those having macro-scopic and those having microscopic or clay vermiculite. This paper is concerned with the former. The macroscopic type of vermiculite deposits can be subdivided into four categories based on the host rock: (1) ultramafic and mafic; (2) gneiss and schist; (3) carbonate rocks; and (4) granitic rocks. Field and laboratory evidence strongly suggests that most and possibly all macroscopic-type vermiculite deposits formed by the action of supergene solutions on biotite and phlogopite. Vermiculite in mixed-layer association with biotite, phlogopite, and chlorite is likewise believed to be of supergene origin.
Genesis of Vermiculite and Mixed-Layered Vermiculite in the Evolution of the Soils of France
Authors: Millot Georges , Camez Thérèse 
Published: August 2006

AbstractAnalysis of the argillaceous fraction of some podzolic soils and podzols of France has shown a double evolution of illite and chlorite through mixed layering into vermiculite. $ilite \to \left( {illite - vermiculite) \to vermiculite} \right) \\ chlorite \to \left( {chlorite - vermiculite} \right) \to vermiculite \\$Vermiculite is more concentrated in the upper zones of the profiles where it constitutes 50 to 90 percent of the argillaceous fraction.
Chloritized Weathering Products of a New England Glacial Till
Authors: Quigley R. M. , Martin R. T. 
Published: August 2006

AbstractThe clay mineralogy of a soil profile developed in a New England glacial till has been studied to a depth of 55 in. Degraded soil micas, probably produced by weathering, have been chloritized by both iron and aluminum hydroxide complexes. Aluminum and iron determinations and X-ray analyses indicate that iron chloritization has played the greater role. Citrate-extractable chlorite exists to a depth of 55 in. X-ray and heat stability data indicate that the chlorite is better developed or crystallized near the surface. X-ray and glycol retention data suggest that intense weathering at the surface has reduced the surface charge density of some of the degraded mica.