bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantitative Clay Mineral Analysis Using Simultaneous Linear Equations
Authors: Johnson L. J. , Chu C. H. , Hussey G. A. 
Published: September 2006

AbstractA program of simultaneous linear equations has been developed to calculate component proportions and/or component property values for mineral mixtures in soil clays and sediments. The analysis is based on quantitatively measured chemical and physical properties of samples and involves (1) qualitative identification of the mineral components in the mixture by any appropriate means; (2) quantitative measure of the sample property values selected for use in the program; (3) estimation of the proportion of each component in the mixture by a technique such as X-ray powder diffraction; (4) assignment of limits to component property ranges; (5) selection of one of four available calculation options and application of the simultaneous linear-equations program; (6) examination of the residuals of the analysis and, if appropriate, adjustment of the initial estimates for component proportions or property ranges and then repeating step 5; and (7) verification of the final component proportions by comparison with information from step 1. Completeness and/or accuracy of the final results for component proportions may be checked by the closeness of approach to 1.0 for the sum of the component proportions. The method requires that, at minimum, the number of properties measured must equal the number of components in the samples being analyzed and that the minimum number of samples must equal the number of properties measured.Using the clay fractions of 15 Pennsylvania soils containing kaolinite, illite, smectite, vermiculite, chlorite, interstratified vermiculite/chlorite, quartz, and noncrystalline material, and measuring methylene blue cation-exchange capacity, the amount of Ca displaced by Mg from a Ca-saturated clay, the amount of K displaced by NH4from a K-saturated clay heated to 110°C, % K2O, % SiO2, % MgO, and weight loss at 110°–300°C and 300°–950°C, the adjustment of property values was found to have the lowest residual value and the most consistent results. The source of analytical errors was also located by examination of residual tables. Samples that were similar in composition gave more reliable component proportions.
Co, Cu, Ni, and Ca Sorption by a Mixed Suspension of Smectite and Hydrous Manganese Dioxide
Authors: Traina S. J. , Doner H. E. 
Published: September 2006

AbstractThe sorption properties of Co, Cu, Ni, and Ca were studied in a mixed mineral suspension of synthetic MnO2 and Wyoming montmorillonite. The distribution of the sorbed cations between the two solid phases was measured by indirect chemical fractionation with acidified NH2OH-HCl and by direct X-ray spectroscopic analysis of mineral particles using electron microscopy. Electron microscope and NH2OH-HCl measurements of the quantity of Co sorbed on MnO2 agreed within 6%. Seventy-seven, 67, and 69% of the total Co, Cu, and Ni sorbed by the mixed mineral suspension was found on the manganese oxide. The opposite distribution was found for sorbed Ca with 28% on the manganese oxide and 72% on the montmorillonite particles. The observed differences in metal sorption by these minerals are related to the cation-sorption mechanisms of manganese oxide and montmorillonite.
Vapor-Phase Sorption and Polymerization of Phenols by Smectite in Air and Nitrogen
Authors: Sawhney B. L. 
Published: September 2006

AbstractReactions of smectite with phenols were investigated to understand the role of clay minerals in abating transport of these organic pollutants to ground water. Sorption of o-methylphenol, o-chlorophenol, and m-methylphenol by the clay with different exchange cations was accomplished by passing phenol vapors in a slow stream of air or nitrogen through the samples. The resulting products, extracted with methanol and analyzed by using mass spectrometry, included monomers, dimers, trimers, and tetramers of the parent phenol and of the corresponding quinones, the oxidation product of the phenols. In extracts from the Fe-clay-phenol complexes formed in air, traces of the phenolic pentamers were also detected. Both sorption and polymerization were much higher in air than in nitrogen. The greatly reduced polymerization in nitrogen suggests that anaerobic environment of the landfill sites may facilitate phenol transport to ground water. The degree of polymerization and its magnitude was in the order Fe- > Al- > Ca- > Na-clay.
Interlayer Water and Swelling Properties of Natural and Homoionic Corrensite
Authors: Brigatti Maria Franca , Poppi Luciano 
Published: September 2006

AbstractA corrensite-like mineral, from near Borgotaro, Parma (Taro Valley, Italy), was studied by X-ray powder diffraction (XRD) and thermal analysis at different temperatures and water vapor pressures in the natural state and after exchange with ten different cations. In the natural state the mineral is characterized by a basal reflection at ∼29 Å shifting to ∼24 Å on heating and to ∼32 Å by glycerol treatment. The dehydration features of the homoionic minerals show that the stability of the complex of water, compensating cation, and silicate framework depends on the electrostatic energy of the water dipole in the cation field, similarly to smectite.XRD of the exchanged mineral shows a basal reflection of ∼58 Å particularly in the NH4-, Rb-, and Ba-exchanged states. This value suggests a structure characterized by a regular sequence of silicate layers with different layer charge, that generally results in a c periodicity of ∼29 Å, but which shifts to ∼58 Å, and perhaps higher values, because of small differences in the compensating cation layers.
Crystallization of Iron Oxides on Calcite Surfaces in Static Systems
Authors: Clarke E. T. , Loeppert R. H. , Ehrman J. M. 
Published: September 2006

AbstractIron salts react readily with calcite in oxidizing calcareous environments to produce solid phase Fe-oxides. These reactions represent important processes in aqueous, geologic, and pedogenic environments. In the present investigation, Fe-oxides were precipitated from Fe(ClO4)2 solutions on undisturbed calcite grains in aqueous suspension. In this way it was possible to investigate the sequence of events in the crystallization process. Following an initial precipitation on the calcite grains, a period of slow growth of lepidocrocite was noted wherein 4-μm euhedral platelets formed with uniform orientation perpendicular to the calcite surface. The slow growth and highly crystalline nature of the Fe-oxide product may be partially due to the diffusion barrier formed by the growing oxide crystal mass which influenced rate of movement of HCO3− to the dissolved Fe phase and Fe ions and H+ towards the calcite surface. Upon continued aging, the supernate became noticeably opaque. As the suspended nuclei settled, new surfaces for crystal growth were provided which resulted in somewhat less crystalline lepidocrocite and goethite.
Influence of Inorganic and Organic Ligands on the Formation of Aluminum Hydroxides and Oxyhydroxides
Authors: Violante A. , Huang P. M. 
Published: September 2006

AbstractHydroxide and oxyhydroxide products of aluminum were formed at room temperature at an initial Al concentration of 2 × 10-3 M, pH 8.2, and at varying concentrations of organic and inorganic ligands commonly found in nature. The effectiveness of the ligands in promoting the formation of noncrystalline products over crystalline Al(OH)3 polymorphs was found to be in the following order: phthalate ≅ succinate < glutamate < aspartate < oxalate < silicate ≅ fluoride < phosphate < salicylate ≅ malate < tannate < citrate < tartrate. The lowest ligand/Al molar ratio at which the production of Al hydroxides or oxyhydroxides was inhibited ranged from 0.02 to 15. Above critical ligand/Al ratios, crystalline products were inhibited and ligands coprecipitated with noncrystalline products which remained unchanged for at least 5 months. Polydentate and large ligands generally were more inhibitive than those with fewer functional groups or of smaller size.The perturbing ligands promoted and stabilized the formation of pseudoboehmite over crystalline Al(OH)3 polymorphs in the following sequence: chloride < sulfate < phthalate ≅ succinate < glutamate < silicate < aspartate < phosphate < salicylate ≅ malate < tannate < citrate < tartrate. The optimal range of the ligand/Al molar ratios for the formation of pseudoboehmite varied, for example, from 0.005–0.015 for tartrate to 600–1000 for chloride. Pseudoboehmite was not formed in the presence of fluoride.
Growth Conditions and Genesis of Spherical and Platy Kaolinite
Authors: Tomura Shinji , Shibasaki Yasuo , Mizuta Hiroyuki , Kitamura Masao 
Published: September 2006

AbstractSpherical and platy kaolinite crystals were prepared under several hydrothermal conditions. Spherical kaolinite was produced mainly at high solid/water ratio (1/4) and at low temperatures (150°-200°C). Platy kaolinite predominated in products from experiments with intermediate solid/water ratios (1/256-1/16) and at high temperatures. Boehmite predominated at low solid/water ratios (1/4096) at all experimental temperatures (180°-220°C). The results indicate that the growth of the spherical kaolinite was favored at high degrees of supersaturation, whereas the growth of the platy kaolinite was favored at relatively low degrees of supersaturation.
Characterization of Dehydration-Induced Luminescence of Kaolinite
Authors: Lahav Noam , Coyne Lelia , Lawless James G. 
Published: September 2006

AbstractDehydration-induced luminescence (DIL), the emission of light from a clay paste upon dehydration, was characterized experimentally for a colloidal kaolinite. The relationship between total photon count of the emitted light and film thickness is linear up to a thickness of 30 μm. The photon emission was obtained over a critical range of water contents (25-60%) of the oven-dry clay, and the kinetics of photon emission was presumed to be closely associated with the kinetics of film dehydration. Whether drying proceeded throughout the bulk or via a moving front was undetermined, but in either mode it was preceded by the formation of a thin dry film at the interface with the atmosphere. Grinding of the kaolinite for several minutes by mortar and pestle before paste preparation resulted in an overall increase of photon emission compared to unground kaolinite and in the formation of more than one emission peak, as well as a prolongation of the light emission. This effect on the kinetics of light emittance was observed for about two months after the application of the mechanical stress and suggests a means of detecting the mechanical stress history of a clay.An estimate was made of the spectral characteristics of the emitted light using optical filters and by incorporating tryptophan and salicylic acid into the kaolinite paste where they acted as fluorescent probes. The latter technique shifted the frequency of the light emitted by the kaolinite from the ultraviolet to the visible range where it was less effectively reabsorbed. The first method showed that the wavelengths of 97% of the emitted light was <460 nm and that 75% of the light had wavelengths <410 nm. The second method showed that the total intensity of DIL increased in the presence of fluorescence molecules, suggesting that the emittance was in the ultraviolet range.
Effect of Simple Sugars on the Alkaline Transformation of Ferrihydrite into Goethite and Hematite
Authors: Cornell R. M. 
Published: September 2006

AbstractThe transformation of ferrihydrite to goethite and hematite in the pH range 9–13 is retarded by the presence of simple sugars (>- 10-4 M concentration). The retarding effect is related to the extent of adsorption of the sugar on ferrihydrite. Maltose and glucose adsorb strongly and inhibit the transformation by preventing both aggregation and dissolution of the ferrihydrite. Sucrose adsorbs to a much lesser extent than the other sugars and appears to hinder the nucleation and growth of goethite in solution.Hematite formation relative to that of goethite is favored by the sugars in the order: maltose >glucose ≫ sucrose. Maltose and glucose cause hematite to grow as prismatic crystals rather than as hexagonal plates and also lead to a new type of twinned goethite; one with epitaxial outgrowths of goethite on a prismatic crystal of hematite. In alkaline media glucose and maltose are partly transformed into a mixture of different sugars and hydroxycarboxylic acids, and it is probable that modification of the hematite crystal shape is due to the presence of the degradation products rather than to the nature of the original sugar.The results of this work suggest that cyclic molecules influence the transformation of ferrihydrite to a lesser extent than do acyclic molecules.
Transmission Electron Microscopic Study of Diagenetic Chlorite in Gulf Coast Argillaceous Sediments
Authors: Ahn Jung Ho , Peacor Donald R. 
Published: September 2006

AbstractTransmission and analytical electron microscopy have been used to study the diagenesis of the trioctahedral component of phyllosilicates (principally chlorite) in argillaceous core samples (depths of 1750, 2450, and 5500 m) from the Gulf Coast. Chlorite was observed as 100-150-Å thick packets intergrown within mixed-layer illite/smectite in the 2450-m sample and was more abundant and larger in packet thickness in the 5500-m sample. The chlorite is disordered in stacking sequence as characterized by diffuseness of reflections with k ≠ 3n in electron diffraction patterns. Berthierine (7-Å) was locally found to be intercalated within chlorite layers. Chlorite from the 5500-m sample is iron-rich and has an average chemical formula of Fe3.1Mg1.1Al2.7Si2.8O10(OH)8. This chemical composition and textural relations suggest that the chlorite formed within mixed-layer illite/smectite utilizing Fe and Mg released from the smectite during its conversion to illite. The berthierine is nearly identical in chemical composition with the coexisting chlorite although it may have a slightly higher Fe content. The 7-Å berthierine is probably a metastable precursor of the chlorite and may be diagnostic of the diagenetic environment.
Mineralogical and Morphological Evidence for the Formation of Illite at the Expense of Illite/Smectite
Authors: Pollastro Richard M. 
Published: September 2006

AbstractThe conversion of smectite to illite by way of a mixed-layer illite/smectite (I/S) series was found to be the major depth-related reaction in clay-mineral assemblages from two cored sedimentary sequences in the Rocky Mountains. The I/S reaction occurred in both interbedded sandstone and shale of Upper Cretaceous and lower Tertiary age in the Green River basin, Wyoming, and in chalk and chalky shale of the Upper Cretaceous Niobrara Formation, Denver basin, Colorado. As the proportion of illite layers in I/S increased with depth in these rocks, the amount of I/S in the clay fraction decreased, and the amount of discrete illite increased. Scanning electron microscopy revealed that the morphologies of highly expansible, randomly interstratified I/S clay (samples from shallow cores) exhibited no distinctive intergrowth or overgrowth textures. In deeply buried rocks containing highly illitic, ordered I/S and abundant discrete illite, however, fibers or laths of illite were formed on earlier I/S substrates. Less commonly, I/S of low expandability shows morphological features of both smectite and illite whereby rigid laths of illite appear to have formed diagenetically from the wall surfaces of I/S honeycombs. This combined morphology suggests some dissolution and reprecipitation (or some reorganization) of materials from the I/S substrate as the substrate was transformed into a more illitic mixed-layer clay.These data suggest that some I/S clay was destroyed by the selective cannibalization of smectite layers in I/S to provide the components needed to make a more illitic I/S. Moreover, discrete illite and other minerals apparently were formed during the reaction. Also, coarser mineral phases, such as potassium feldspar and detrital micas, may not have been required to supply the chemical components in the reaction. The observations provide an explanation for late diagenetic I/S reactions that occurred in restricted or relatively closed geochemical systems, as in early cemented rocks having extremely low permeability and little or no potassium feldspar.
Review of the Diffusion of Water and Pyridinein the Interlayer Space of Montmorillonite: Relevance to Kinetics of Catalytic Reactions in Clays
Authors: Breen Christopher , Adams John M. , Riekel Christian 
Published: September 2006

AbstractWith the current interest in the use of transition metal-exchanged phyllosilicates as catalysts for novel organic syntheses, investigations into the factors which affect the movement of reactant, product, and solvent molecules into and out of their interlamellar region are of considerable importance. Mixed organic-water intercalates of a Wyoming montmorillonite, exemplified by the Na-montmorillonitepyridine-water system which can form four different intercalates exhibiting basal spacing of 29.3, 23.3, 19.4, and 14.8 Å depending on the pyridine: water ratio, have been used as a model system. X-ray and neutron diffraction and quasielastic neutron scattering data relating to the interconversion of interlayer species indicate that access to and exit from the interlayer space is hindered at high partial pressures of water by a water-film diffusion barrier in the interparticulate voids which exist between the aggregated silicate layers. At lower water vapor pressures the rate-limiting step for interconversion from one intercalate to another is the rate of transport of reagents and products to and from the clay particles. Under conditions where these rates are fixed, the rate-limiting step is the rate of diffusion of the pyridine molecule in the lower-spacing intercalate. Processes which involve a change in basal spacing do not necessarily proceed via a single discrete step, but are also affected by the amount of water made available to the system. In organic reactions catalyzed in the interlamellar space of various cation-exchanged montmorillonites (e.g., the conversion of alk-1-enes to di-2,2’-alkyl ethers and the reaction of alcohols to form ethers), rate-determining steps similar to those found above are likely to be operative. In particular, for reactions carried out in the liquid phase, where mass transport is facile and where phase-transfer problems are avoided, such reactions are likely to be diffusion controlled.
Adsorption of Dimethylanilines on Montmorillonite in High-Pressure Liquid Chromatography
Authors: Mingelgrin U. , Tsvetkov F. 
Published: September 2006

AbstractHigh-pressure liquid chromatography columns were packed with quasi-spherical particles of bentonite (SP-bentonite) which were prepared from a predominantly Na-bentonite powder by spray drying. The strength of adsorption of ring-substituted dimethylanilines on bentonite was directly related to their basicity (pKa). The adsorption of the amino-substituted N, N-dimethylaniline was commonly much weaker than that predicted from its pKa, suggesting that the amino group was the dominant site of interaction between the substituted anilines and the clay.A better separation between the dimethylaniline isomers was obtained on SP-bentonite than on a neutral silica under the same chromatographic conditions. A selectivity factor of 25 was achieved between the most strongly and the least strongly adsorbed ring substituted isomers (3, 5- and 2,6-dimethylaniline, respectively) on the SP-bentonite. The selectivity factor was 3.4 on the silica. This efficiency of separation demonstrated the potential advantage of the readily available bentonite in high-pressure liquid chromatography. The higher resolution achieved in column runs than in batch experiments may be utilized for the elucidation of mechanisms of interaction of organic molecules at clay surfaces by comparing the interaction of a number of closely related adsorbates.
Influence of Citric Acid on the Formation of Short-Range Ordered Aluminosilicates
Authors: Inoue K. , Huang P. M. 
Published: September 2006

AbstractReactions between hydroxy-Al ions and orthosilicic acid as influenced by citric acid were studied at an initial Si concentration of 1.6 × 10−3 M, Si/Al molar ratios of 0.5 and 1.0, OH/Al molar ratios of 1.0-3.0, and citric acid/Al molar ratios of 0-0.3. In the absence of citric acid and at OH/A1 ratios of 1.0-2.8, imogolite (>0.01 μm) was dominant in the precipitates. At citric acid/Al ratios of 0.01-0.1, imogolite and/or pseudoboehmite were dominant in the precipitates at OH/Al ratios of 1.0 and 2.0, and imogolite and/or ill-defined aluminosilicate complexes at OH/Al ratio of 2.8. Instead of allophane or “proto-imogolite” allophane being the predominant species in the precipitates, the formation of ill-defined aluminosilicate complexes at OH/Al ratio of 3.0 was steadily promoted by increasing the solution citric acid/Al ratios from 0 to 0.3. The freeze-dried soluble products (<0.01 μ) ranged from silica gel to “proto-imogolite,” depending upon the basicity of Al and the level of citric acid of the parent solution. The amount of “proto-imogolite” increased with increasing citric acid/Al ratios from 0 to 0.1 in solution. Complexing low molecular weight organic acids, such as citric acid, impeded the formation of the short-range ordered aluminosilicates, allophanes and imogolite.