bluuebunny/crossref_metadata_2025_split huggingface dataset:
Geochemical Mechanics for the Dissolution, Transport, and Deposition of Aluminum in the Zone of Weathering
Authors: Huang W. H. , Keller W. D. 
Published: September 2006

AbstractOrganic acids in the 0·01M concentration range representing amino-, aliphatic, and aromatic types present in humus dissolve 70–85 ppm Al from Arkansas bauxite at room temperature, whereas 0-03 ppm is dissolved in water. The species of Al in aqueous solution, calculated from stability data, range from Al3+ at pH 3 and lower, through Al2(OH)24+ at a maximum concentration at pH 4·5, Al(OH)2+ at a maximum at pH 4·7, Al(OH)2+ at a maximum at pH 60, to Al(OH)4- at pH 8·5 and higher. In salicylic acid an Al-Sal+ complex occurs between pH 1·5 and 8·5, and is at a maximum at pH 4·2. Solubility of Al obviously is pH dependent; also because of the vulnerability of organic acids to oxidation, the solubility and transport of Al is indirectly Eh dependent. Anions that combine with Al include OH- to form bauxite, PO43- to form lateritic phosphate such as the Bone Valley Formation, Fla., and SiO44- to form allophane or kaolin as noted in the kaolin synthesis by Linares and Huartes. Spongelike, pisolitic or oolitic structures, and mineral veins in bauxites, lateritic phosphates, and some flint clays attest to mobilization of Al in solution. Lignites and humus zones associated with latentes are a logical geologic source of these complexing organic solvents. Although Al is inherently mobile, such commonly available precipitating anions render Al relatively immobile.
Catalytic Activity of Sodium Kaolinites
Authors: Hawthorne D. G. , Solomon D. H. 
Published: September 2006

AbstractKaolinites, catalytically active for the polymerization of styrene, can be deactivated by treatment with 1N aqueous sodium chloride. Subsequent washing of the sodium kaolinite results in a facile hydrolysis yielding an active hydronium/aluminum kaolinite in which the exchangeable cations act as surface Br0onsted acid initiation sites.
The I.R. Spectra of Lysine Adsorbed on Several Cation-Substituted Montmorillonites
Authors: Do Jang Sung , Condrate Robert A. 
Published: September 2006

AbstractThe i.r. spectra (4000-1200 cm-1) are obtained for several cation-substituted-montmonl-lonite-lysine complexes that were prepared at their natural pH’s. Analyses of the spectra of copper-, cobalt-, nickel- and zinc-montmorillonite films indicate that bidentate chelate complexes which contain protonated ∈-amino-groups are present in the interlamellar spaces. Investigation of the spectra of the hydrogen-, calcium- and natural-montmorillonite films indicates that the dominant adsorbed species for these complexes is a lysine cation in which both the α- and the ɛ-amino-groups are protonated while the carboxyl group is ionized.
Relation Between Swelling, Water Properties and b-Dimension in Montmorillonite-Water Systems
Authors: Ravina Israela , Low Philip F. 
Published: September 2006

AbstractThe b-dimensions of the unit cells of six different Na-saturated montmorillonites were determined by X-ray diffraction at water contents ranging from 0 to 20 g per g of montmorillonite. In every case, the b-dimension increased progressively with water content from its initial value, which was characteristic of each dry montmorillonite, to a final value of ~9•0Å, which was common to all montmorillonites. The latter value was reached when the water contents of the respective montmorillonites were equal to those at maximal swelling. When these water contents were plotted against the corresponding changes in b-dimension, a straight line that passed through the origin was obtained.Different structure-sensitive properties of the water in montmorillonite-water systems (i.e. the partial specific volume, the amount remaining unfrozen at −5°C and the activation energy required for ions to move through it) were available, as functions of the species of exchangeable cation, from previous studies. Relevant b-dimensions were determined in the present study. It was found that all of these water properties were correlated with the b-dimension of the associated montmorillonite.Our results indicate that epitaxy exists between the crystal lattices of montmorillonite and adsorbed water and that these lattices undergo mutual adjustment with each increment of water. The resulting loss of free energy causes water adsorption, i.e. swelling, to occur spontaneously. Swelling stops when no further adjustment takes place. This does not happen until the adsorbed water is several hundred angstroms thick and has achieved a preferred configuration.
Acid-Base Interactions and the Properties of Kaolinite in Non-Aqueous Media
Authors: Solomon D. H. , Murray H. H. 
Published: September 2006

AbstractIn non-aqueous systems, kaolinite can show, in addition to the physical interactions, considerable chemical activity. This study considers the chemical reactions that can occur at the kaolinite surface and explains these reactions in terms of acid-base interactions. In certain applications the chemical activity must be controlled if satisfactory products are to be obtained; for example, when kaolinite is used as a filler in rubber or as a diluent for insecticide powders. The concept of acid-base interactions is used to explain rheological and film properties in kaolinite-organic systems. The strength of the surface acid sites of kaolinite varies with the moisture content. At 1% moisture the surface is equivalent to 48% sulphuric acid whereas at 0% it is equivalent to 90% sulphuric acid. Therefore, the moisture level is extremely important and dry kaolinite will promote or catalyze many chemical reactions and where acid-base interactions are involved the presence of even small amounts of water usually retards or inhibits the reaction. Several examples explaining these interactions are given in the paper.
The Transformation of Lepidocrocite to Goethite
Authors: Schwertmann U. , Taylor R. M. 
Published: September 2006

AbstractThe conversion of lepidocrocite (-γFeOOH) to its more stable polymorph, goethite (αFeOOH) was followed by observing changes in crystal morphology, oxalate solubility, surface area and X-ray diffraction. In conjunction, kinetics were measured as functions of surface area, temperature, alkalinity and seeding with goethite crystals.The results suggest that the transformation is not topochemical, but proceeds through the solution phase. The main steps governing the rate of transformation are, (1) the dissolution of lepidocrocite, and (2) the formation of goethite nuclei and subsequent growth. Either of these processes can be rate-determining under appropriate conditions.
The Influence of Silicate on the Transformation of Lepidocrocite to Goethite
Authors: Schwertmann U. , Taylor R. M. 
Published: September 2006

AbstractThe mechanism of the transformation of lepidocrocite (γFeOOH) to goethite (αFeOOH) has previously been established and the effect of silicate on the transformation was investigated. Rather than completely inhibiting the reaction, as had been suggested, the presence of Si was found to merely retard the nucleation stage of the transformation. There was found to be no decrease in the dissolution rate of the lepidocrocite due to surface adsorption of Si.Si has no effect if introduced after the nucleation stage, and under conditions of pH and temperature where the dissolution rate of the lepidocrocite largely determines the rate of transformation, the presence of Si has a reduced effect. The results show that Si is adsorbed and incorporated into the goethite structure, and due to its retarding effect on the nucleation, larger crystals of goethite are formed, many of which are twinned.It is inferred from the results that the apparent stability of lepidocrocite occurring in soils in association with goethite cannot be attributed solely to the presence of Si in the soil system.
Some Naturally Occurring Illite-Smectite Interstratifications
Authors: Heller-Kallai L. , Kalman Z. H. 
Published: September 2006

AbstractTwo different types of interstratified illite-smectite are found in a section of Paleozoic sediments in the Negev, Israel. One of these is detectable only by a decrease in peak width and a concomitant increase in symmetry of the 10 Å peak on glycolation. This material is regarded as illite, randomly interstratified with about 20 per cent expanding layers.
Recognition of Interstratified Clays
Authors: Mills J. G. , Zwarich M. A. 
Published: September 2006

AbstractDifficulties in the interpretation of X-ray diffractograms of soil clays are discussed with reference to clay fractions obtained from glacial till and lacustrine soil parent materials. Diffracto-grams of the coarse clay fractions are readily interpreted by conventional means but it is difficult to determine if the dominant mineral species of the fine clay fraction is an interstratified mineral or a mixture of discrete montmorillonite and mica. A number of methods of interpretation of diffractograms of interstratified minerals are used with varying results. In the case of clays of small particle size, diffraction peaks crucial to the recognition of interstratification are not resolved due to the peak broadening. This phenomenon causes the diffractogram of a mixture of discrete minerals to resemble that of an interstratified mineral.
Interlamellar Metal Complexes in Layer Silicates III Silver(I)—Arene Complexes in Smectites
Authors: Clementz D. M. , Mortland M. M. 
Published: September 2006

AbstractThe complexation of benzene and several methyl substituted benzenes with exchangeable silver(I) on the interlamellar surfaces of Ag(I)-montmorillonite has been studied using spectroscopic methods. There are no physically adsorbed molecules interacting with the internal silicate surfaces and the only chemisorbed species present are those which are coordinated through π electrons to the exchangeable Ag(I) ions. In each case the coordinated species are similar to the previously studied Cu(II)-montmorillonite Type I complexes where aromaticity is retained. Complete replacement of coordinated and other interlamellar water molecules was accomplished with relative ease. Stoichiometric determinations indicate a 2:1 benzene: Ag(I) complex. Similarities between the Cu(II) and Ag(I) complexes are discussed in relation to electronic configurations.
A Sepiolite-Rich Playa Deposit in Southern Nevada
Authors: Papke Keith G. 
Published: September 2006

AbstractSepiolite is seldom reported in playa deposits, even though it is generally believed to form in a highly saline, alkaline environment. Its rareness suggests that unusual conditions are necessary for formation of sepiolite. Sepiolite is a major constituent of a near-surface playa bed 4 ft thick in the Amargosa Desert, southern Nye County, Nevada. Associated materials include dolomite and small to trace amounts of quartz, feldspar, montmorillonite, illite, and volcanic glass. The dolomite, averaging about 2μ in size, makes up about 40% of the bed. The overlying beds and the underlying ones down to a sampled depth of 13½ ft are montmorillonitic (saponite) clays with moderate to trace amounts of sepiolite; dolomite is abundant in all these clays except in the uppermost several feet, where calcite is a major constituent. Ground water in this area contains abundant magnesium compared with that in the rest of the Amargosa Desert. An initial high concentration of magnesium in the playa lake water probably promoted the development of sepiolite and dolomite. Concentration of dissolved salts through evaporation of water is believed to have started chemical precipitation of dolomite, and this precipitation and the continued evaporation later caused deposition of sepiolite.
A Ferroan Nontronite from the Red Sea Geothermal System
Authors: Bischoff James L. 
Published: September 2006

AbstractA smectite rich in ferrous iron and low in aluminum occurs abundantly in the Red Sea Geothermal Deposits, and appear to be forming at present.Chemical analyses and Mössbauer spectra indicate the mineral is intermediate in composition between nontronite and the as yet undescribed trioctahedral ferrous iron end member.
Formation of an Interstratified Mineral by Extraction of Potassium from Mica with Sodium Tetraphenylboron
Authors: Tomita Katsutoshi , Dozono Mitsuhiko 
Published: September 2006

AbstractInterlayer K was extracted with sodium tetraphenylboron solution from a powdered sericite heated to the temperature of dehydroxylation and quenched to room temperature. By this procedure, sericite of the 2M1 type was changed to an interstratified mineral. The X-ray diffraction properties of this interstratified mineral are similar to “rectorite”.
The Relationship Between the Hydrated and Dehydrated States of an Halloysite
Authors: Churchman G. J. , Aldridge L. P. , Carr R. M. 
Published: September 2006

AbstractA study of the mineralogical changes taking place during the loss of interlayer water in an halloysite has been carried out in order to clarify the relationship between the most hydrated and least hydrated states of the mineral. A number of samples of halloysite which together exhibit a variety of average interlayer water capacities were obtained by the conditioning of a largely hydrated sample with different atmospheres of known relative humidities. Profiles were obtained of X-ray peaks which characterize the interlayer water capacities of halloysite samples. An attempt has been made to analyse these profiles into a sum of peaks attributable to the fully hydrated and dehydrated states of the mineral. Such an analysis does not satisfactorily explain the profile shapes. A mechanism of interstratification of hydrated and dehydrated kaolin layers in which there is a tendency towards the segregation of these layer types gives a more satisfactory explanation of these profile shapes. It is concluded that dehydration takes place through an interstratification in which there is a partial segregation of the two basic layer types. This conclusion implies that halloysites with all average interlayer water contents between 0 and 2 molecules per unit cell may exist and that fully hydrated halloysite and dehydrated halloysite are the end members of a continuous series of hydration states.
A Chloritized Montmorillonite from the Rio Chiflon Formation (TR) of Argentina
Authors: Bossi Gerardo E. 
Published: September 2006

AbstractX-ray, chemical, and genetic characteristics of a chloritized montmorillonite mineral species, found in The Río Chiflón Formation (La Torre, La Rioja, Argentina) are described. The mineral is associated with illite, montmorillonite, and chlorite, plus the non-clay associates analcite and hematite. The Río Chiflón Formation is of Upper Triassic age, and consists of red sandstones and siltstones representing poorly developed fluviatile cyclothems.Studies of the Li+, K+ and Mg2+ varieties of the clay, and solvation with glycerol or ethylene glycol have shown that the mineral is a smectite which behaves peculiarly with heating. Between 200° and 600°C the mineral collapses gradually from a basal spacing of 13–10 Å. Regular expansibility with ethylene glycol and glycerol is completely preserved (in the Li+ and K+ clays) up to a preheating of 400°C and partially preserved up to 600°C. This behavior has been interpreted as caused by the presence of interlayer contaminants of a hydroxy-cation type. The interlayer cations may be Al, Mg, and Fe, (in this order).The environment of the Río Chiflón Formation has been evaluated in the light of well-known occurrences of intergradient clays in soils, and the presence of analcite and hematite. It is proposed that chloritization has taken place during a soil weathering process, under alkaline conditions with great availability of sodium during alternating dry-humid seasonal climates (oxidation conditions). The stability of the interlayer developed under these circumstances was increased during long burial and diagenesis.
Directional Variation of Elastic Wave Velocities in Oriented Clay
Authors: Franklin Arley G. , Mattson Phillip A. 
Published: September 2006

AbstractSonic anisotropy of clay resulting from particle orientation was studied by means of velocity measurements on anisotropically consolidated kaolinite. Samples were prepared from a kaolin-water slurry under consolidation pressures ranging from 80 to 400 psi, with two distinct stress histories. Directional velocity measurements were made over a wide range of water contents as saturated samples were allowed to dry by evaporation to water contents below the shrinkage limit. Directional variation was most pronounced with partial saturation, when directional velocities differed by as much as a factor of two. The degree of sonic anisotropy is seen to correlate with variation in the shrinkage limit, showing a systematic dependence on particle orientation, but no unique relation to consolidation stress exists because of the overriding influence of stress history.
Morphological Effects on Illite as A Result of Potassium Depletion
Authors: Huff Warren D. 
Published: September 2006

AbstractSeveral illites and a mixed-layer illite-montmorillonite developed fractures in some particles during progressive removal of interlayer potassium by solutions containing sodium tetraphenylboron. The appearance of the splinters in bundles, some connected to incompletely broken plates, suggests the process is related to the differential release of stresses known to exist as a consequence of octahedral-tetrahedral misfit. The formation of splinters produces additional surface area for ion removal and may influence the rate of vermiculite development.
The Oxidation of Octahedral Iron in Biotite
Authors: Gilkes R. J. , Young R. C. , Quirk J. P. 
Published: September 2006

AbstractOxidation of octahedral ferrous iron in biotite by saturated bromine water results in a loss of both octahedral and interlayer cations. The hydroxyl adjacent to vacant octahedral cation sites adopt an inclined orientation resulting in a more stable environment for interlayer cations. The only structural change accompanying these processes is a decrease in b-axis dimension which is linearly related to octahedral ferric iron content. These findings are in agreement with observations made on naturally weathered biotites.
Zeolite as Catalysts for the Synthesis of Amino Acids and Purines
Authors: Fripiat J. J. , Poncelet G. , Van Assche A. T. , Mayaudon J. 
Published: September 2006

AbstractThis paper attempts to show that the catalytic properties of zeolitic material may play a role in the synthesis of simple biological molecules from gases commonly found in extraterrestrial atmospheres. Linde X and Y molecular sieves cation-exchanged by Ca2+ and Fe3+ have been heated in the presence of carbon monoxide and ammonia. Amino-acids and u.v. absorbing substances identified by paper chromatography have been extracted from the solid. HCN, the basic molecule involved in the synthesis of those substances has been detected in the gas phase. It is proposed, on the basis of i.r. results, that the amino-acids are hydrolysis products of an undefined polymer.
Laboratory Alteration of Trioctahedral Micas
Authors: Hoda Syed N. , Hood William C. 
Published: September 2006

AbstractArtificial alteration of thirty-five trioctahedral and one dioctahedral micas by solutions varying in strength from 0·001 to 1·00 molal magnesium sulfate was found to approximate a normal exchange reaction after surface effects are eliminated. The equilibrium constants for the reaction:1/2Mg2++K−mica=Mg1/2−mica+K+(vermiculite)$1/2 {Mg^{2+}}+K-mica=Mg_{1/2}-mica+K^+(vermiculite)$range from 0·0001 to 0·0028 and average 0·0010 in value. X-ray diffraction study reveals that iron-rich micas tend to develop a 1:1 mixed-layer biotite-vermiculite structure in weak magnesium sulfate solutions whereas magnesium-rich biotite and phlogopite alter to vermiculite. Mica composition also influences the degree of alteration of mica to vermiculite. High fluorine and octahedral multivalent cation contents tend to retard the reaction whereas high magnesium content and perhaps high calcium contents tend to favor the alteration. The equilibrium constant data indicate that vermiculite and hydrobiotite are more stable than trioctahedral micas in most weathering environments.
Chlorite Examination by Ultramicrotomy and High Resolution Electron Microscopy
Authors: Brown J. L. , Jackson M. L. 
Published: September 2006

AbstractMafic chlorite from Benton, Arkansas was comminuted by rotary blending of a suspension, and the — 2 μm fraction separated by sedimentation in H2O. Droplets of suspension of the < 2 μm fraction were dried on a layer of Epoxy resin and then additional Epoxy was added and heat-cured at 48°C to form a resin sandwich. Cross-sections of 600–900 Å thickness were cut on a Reichert automated ultramicrotome. The sections were collected on standard electron microscope specimen screens, reinforced by vacuum evaporated C and examined by transmission electron microscopy (TEM). The Phillips EM 200 electron microscope was equipped with a “microgun” source to minimize heating of the specimen and to improve contrast and high resolution (HREM). Images of the (001) chlorite crystallographic planes spaced at 13·9Å intervals were visible on many of the particle sections. Imaging of the planes depended upon their being nearly parallel to the electron beam (within 0° 10’) and therefore, many particles which had other orientations did not show the 13·9Å image. Micrographs made before appreciable irradiation by the electron beam revealed images of fringes corresponding to the 7·22Å (002) spacing of chlorite. Loss of the 7·22 Å fringes and reinforcement of those at 13·9 A resulted from heating of the chlorite in the electron beam. This behavior is analogous to the well-known crystallographic effects of heating chlorite at 550–760°C.
The Effect of Cation Exchange of Tris(Ethylenediamine)Cobalt (III) for Sodium on Nitrogen Sorption by Montmorillonite
Authors: Knudson M. I. , McAtee J. L. 
Published: September 2006

AbstractThe cation exchange process between tris(ethylenediamine)cobalt(III) and Na+ on mont-morillonite was studied by atomic absorption spectrophotometry, X-ray diffraction, differential thermal analysis, and nitrogen sorption at 78°K. The exchange of Co(en)33+ for Na+ was found to be extremely favorable, with a tendency toward segregation of the two kinds of cations in the mixed clays studied. Small amounts of Co(en)3+3 were found to lower the nitrogen sorption capacity of Na+ mont-morillonite while clays with high Co(en)3+3 content had greatly enhanced sorption. An explanation is offered in terms of a dual role of the Co(en)3+3 in determining the kind and amount of nitrogen sorption in the exchanged montmorillonite.
The Nature of Garnierites — II Electron-Optical Study
Authors: Uyeda Natsu , Hang Pham Thi , Brindley G. W. 
Published: September 2006

AbstractElectron micrographs of 7 Å-type and 10 Å-type garnierites have been recorded at 5·104–105X magnifications to show the morphological character of these minerals, and at 106X magnification to show structural features of the particles. The 7 Å, serpentine-like minerals show a greater variety of morphological forms including tube- and rod-shaped particles and also platy forms and poorly defined, fluffy particles, probably aggregates. The 10 Å, talc-like minerals show mainly platy forms and fluffy aggregates, and generally very few tube or rod-shaped particles. At 106X magnifications, the 7 and 10 Å layer spacings are seen directly. In the samples examined, the 7 Å spacings are more clearly and more regularly defined than the 10 Å spacings.