bluuebunny/crossref_metadata_2025_split huggingface dataset:
Triethylene Diamine-Clay Complexes as Matrices for Adsorption and Catalytic Reactions
Authors: Mortland M. M. , Berkheiser V. 
Published: August 2006

AbstractComplexes of 1,4-diazabicyclo [2.2.2] octane (triethylene diamine) with smectite and vermiculite were made for the purpose of exposing the internal surfaces of the clays for adsorption of gases and possible catalytic activity. When the diprotonated form of the amine saturated the exchange sites, internal surfaces of the clays were found to be available to nitrogen, ethane, and 2,4-dimethyl pentane. Proton lability in the smectites was studied with NH3, D2O, and C6D6 experiments. Catalytic function was demonstrated in the conversion of acetonitrile to acetamide in the smectite.
A New Nuclear but Non Radioactive Method for Rapid Elemental Analysis of Clays
Authors: Demortier G. , Hoffelt-Fontaine G. 
Published: August 2006

AbstractA method using the bombardment of samples with protons and other positive ions of energy in the MeV range is described: the prompt atomic (γ-rays) and nuclear (γ-rays and charged particles) events generated during the bombardment, are detected with energy sensitive solid state detectors: cooled Ge(Li) for γ-rays and hard γ-rays, cooled Si(Li) detectors for soft γ-rays (3–20 keV) and Si-barrier detectors for charged particles. These 3 types of detectors can be simultaneously used for multipurpose experiments. These techniques are particularly useful for simultaneous detection of all the elements of interest in the sample. Comparisons are made with other microtechniques. Analyses of Li, Na, K, Ca, Rb, Cs and Cl exchanged in appropriate chloride solutions have been achieved for several clays (Geisenheim, Isola di Ponza, Layton). A new phenomenon relative to the anion contribution in cation exchangers is observed. A method of profile analysis of Na by resonant nuclear reactions is discussed.
The Influence of Crystallite Size on the Apparent Basal Spacings of Kaolinite
Authors: Trunz Volkmar 
Published: August 2006

AbstractFor very small crystallites diffraction theory shows not only broadening of powder lines, but generally also a shift of the line position, depending on the change of the structure factor over the range of broadening. For decreasing thickness of kaolinite crystals (less than 50 layers) an increasing shift of reflections is found: the lines (001), (002), (004) and (006) are shifted to apparently larger spacings, the lines (003) and (005) to smaller spacings, resulting in a nonintegral series. Presuming a known crystallite size, tables are given for evaluating true spacings from measured values of 2θ.
Origin and Position of Exchange Sites in Kaolinite: An ESR Study
Authors: McBride Murray B. 
Published: August 2006

AbstractElectron spin resonance (ESR) spectroscopy is used to investigate the nature of exchange sites on kaolinite. ESR spectra of exchangeable Cu2+ and Mn2+ on kaolinite indicate that divalent exchange ions are about 11–12Å apart on kaolinite surfaces and that planar Cu (H2O)42+ ions are oriented parallel to the surfaces. Solution-like spectra for exchangeable Cu2+ and Mn2+ are observed at high relative humidities, suggesting a high degree of mobility of exchange cations on kaolinite surfaces. The evidence seems to eliminate edge sites as being active in cation exchange at least in the acidic range of pH. Similar conclusions are derived from ESR studies of Cu2+-saturated talc and pyrophyllite. It is proposed that most exchange sites arise from ionic substitutions or mineral impurities in phyllosilicates.
Scan Electron Micrographs of Kaolins Collected from Diverse Environments of Origin—I
Authors: Keller W. D. 
Published: August 2006

AbstractScan electron micrographs are shown of (1) kaolinite and dickite which crystallized from solution within cavities, (2) kaolinite weathered from clastic primary silicate material, (3) residual kaolinite from primary silicate rock, (4) kaolinite above and below a basal unconformity on granitic rock, and (5) hydrothermally altered kaolinite. The texture of kaolin reflects the environment in which the clay was formed.Euhedral crystals of kaolin minerals characterize cavity fillings. The weathering environment produces large crystal flakes of kaolinite, expanded books, mats of elongates, high porosity, and low bulk density (less than 2.0). The hydrothermal environment produces smaller crystals, singles, sheaves and packets of crystals, low porosity and high bulk density (2.0 and above).The interrelationships of genetic environment of kaolin minerals and accompanying texture are discussed in light of available geochemical information.
Effect of Compaction on the Pore Fluid Chemistry of Montmorillonite
Authors: Rosenbaum Michael S. 
Published: August 2006

AbstractAn apparatus for consolidating fine grained materials under controlled conditions of total stress, pore fluid pressure and temperature is described and the variation in chemistry of pore fluid expelled during compaction from a montmorillonitic material at 40°C is reported. The decrease in concentration of dissolved salts in the pore fluid is related exponentially to the effective axial pressure.
The Orientation of Ornithine and 6-Aminohexanoic Acid Adsorbed on Vermiculite from Polarized I.R. ATR Spectra
Authors: Raupach M. , Janik L. J. 
Published: August 2006

AbstractDeterminations of the molecular orientation of ornithine and 6-aminohexanoic acid on the surface of vermiculite using polarized i.r. attenuated total reflectance have shown that the ornithine molecules lay almost flat on the clay surface, except for a C–N bond projecting towards, and hydrogen bonded to, the surface. Ornithine formed two adjacent layers in the interlayer space, whereas 6-aminohexanoic acid formed only one layer. The terminal C-N bond of 6-aminohexanoic acid was at 46° to the surface, the plane of the carbon chain having a tilt of 34°, and the molecular axis sloped at 36° to the surface. The amino acids, thus orientated, were positioned in the interlayer space using van der Waals contact distances and hydrogen bond lengths obtained from i.r. spectra. The i.r. results agreed with two dimensional electron density projections. In the ornithine complex, some of the methylene groups were so close to the clay surface that interaction may have caused the marked reduction observed in the intensity of the C–H stretching vibrations.
Tosudite from the Hokuno Mine, Hokuno, Gifu Prefecture, Japan
Authors: Ichikawa Atsuko , Shimoda Susumu 
Published: August 2006

AbstractTosudite was found in the Hokuno pottery stone mine, Gifu Prefecture, Japan. The pottery stone ore body, altered from the Cretaceous rhyolitic rock, is composed of tosudite, interstratified illite-montmorillonite, kaolinite and quartz. Prepared by normal sedimentation method, the specimen is composed of 75.6% tosudite, 24.0% kaolinite and 0.4% quartz. The chemical composition of the specimen is SiO2 45.09%, TiO2 tr., Al2O3 37.31%, Fe2O3 0.94%, MgO 0.41%, CaO 1.94%, Li2O 0.45%, Na2O 0.09%, K2O 0.44%, H2O(−) 1.50% and ignition loss 12.11%. After subtracting the compositions of the impurities, the structural formula of tosudite is given as; interlayer cations K0.23, Na0.07, Ca0.86 + nH2O; ‘gibbsite’ layer Li0.76, Mg0.35, ${\rm{Fe}}_{0.29}^{3 + }$, Al3.34 (OH)12.00; silicate layer Al8.00 [Si13.83 Al2.17] O40.00 (OH)8.00.Syntheses of tosudite were made from a starting material which is an interstratified illite-montmorillonite obtained from the same ore body. At 450°C, 400atm., reacting for 5 days, a tosudite-like mineral was synthesized.
Stability of Soil Smectite From a Houston Black Clay
Authors: Carson C. D. , Kittrick J. A. , Dixon J. B. , McKee T. R. 
Published: August 2006

AbstractThe stability of smectite separated from a Houston Black clay soil was studied by solubility methods in an acid environment. High Silicon levels (supersaturated with respect to amorphous Si) probably were due to dissolution of the smectite and slow precipitation of amorphous Silicon. Also, mica and vermiculite impurities may have contributed to high solution Si values. Solubility data from equilibrium solutions of various treatments and chemical structural analyses permitted the formulation of a solubility equation. The ΔG°f for the Houston Black smectite computed from pK values was —2433.9 ± 0.8 kcal/mole. The stability of this clay could then be determined by calculations for any desired solution environment. It was found that under some conditions this soil smectite could be more stable than Belle Fourche and Aberdeen montmorillonites. Therefore, it appears that this soil clay has the required stability area in which it can form in nature.
Transformations of Micas in the Process of Kaolinitization of Granites and Gneisses
Authors: Stoch Leszek , Sikora Wanda 
Published: August 2006

AbstractMicas are described from the kaolin type Tertiary weathering crusts formed on granites and gneisses of Lower Silesia, Poland. In the weathering crust, large scale processes of transformation of micas (muscovite, biotite) take place. Weathering of micas is a gradual transformation of their structures by removal of the mobile cations Mg2+ Fe2+ Fe3+ and finally K +. Muscovite transforms into kaolinite through the intergrowths of two phases, mica and kaolinite. A degradation series, muscovite → mica/montmorillonite → montmorillonite → kaolinite also is observed. Biotite passes directly into kaolinite, but at higher concentrations of K and Al one observes the following sequence of biotite degradation: biotite → dioctahedral mica rich in Fe → dioctahedral mica poor in Fe → kaolinite. This process involves the exchange of Mg2+ and then Fe2+ of octahedral layers by Al3+ less mobile under weathering conditions. In the next stage of degradation, K + removal and kaolinite formation takes place. The micas representing different stages of this transformation, dark green, light-green, and silver-white, have been separated and investigated.
Protonation of Organic Bases in Clay—Water Systems
Authors: Karickhoff Samuel W. , Bailey George W. 
Published: August 2006

AbstractThe extent of protonation of organic bases in clay—water systems depends upon the adsorptive properties of the organo-clay species involved, and upon the structure and degree of hydration of the clay system. Organic molecules that can disperse cationic charge over two or more condensed aromatic rings give rise to greater surface-induced protonation than do single-ring organic molecules with similar solution pKa. Protonation in clay suspensions is frequently far in excess of that predicted on the basis of electrolytic suspension pH and solution pKa of the organic base. For a given organic base, protonation in a clay film exceeds that in the suspended clay system. Protonation in an organo-clay film increases as the film moisture content decreases. The extent of protonation in organo—clay systems varies with cationic species, cationic saturation, and clay type.
Organic Derivatives of Attapulgite—I. Infrared Spectroscopy and X-Ray Diffraction Studies
Authors: Mendelovici E. , Carroz Portillo D. 
Published: August 2006

AbstractHighly significant differences are observed between the methyl derivatives of attapulgite, produced when this mineral is reacted with (CH3)2Si(OC2H5)2, in the presence or in absence of HCl. In the first case, the corresponding infrared spectra show characteristic absorption bands due to the Si(CH3)2 radicals at 1260, 850 and 800 cm−1 as well as a shoulder at 960 cm−1, the latter assigned to silanol groups. The 850 cm−1 frequency which is usually exhibited by trimethylsilicon compounds is also detected when —O—Si(CH3)2 radicals are grafted in the silicates, but only if HCl is present in the reaction. Neither this band nor the 960 cm−1 shoulder appear in the spectrum of the derivative synthetized in absence of HCl. A comparative study by both i.r. spectroscopy and X-ray diffraction does not reveal structural modifications in attapulgite after it has been methylated in absence of HCl. However, although the i.r. spectra of the HCl-methylated derivatives, prepared at different periods, do not indicate substantial structural perturbations, X-ray diffraction patterns show a gradual weakening of the peaks due to attapulgite, as reaction time increases; the intensity of the (110) order reflection is drastically reduced after a 165 hr attack. The most viable mechanism for the grafting of the dimethylsiloxy units in attapulgite is through the HCl induced silanol sites. When the reaction is taking place in anh. benzene medium (absence of HCl), dimethyldiethoxysilane may be hydrolyzed by a fraction of water contained in attapulgite; the hydrolysis products which do incorporate on the surface of the silicate are identified by i.r. spectroscopy.
Experimental Alteration of a Chlorite into a Regularly Interstratified Chlorite-Vermiculite by Chemical Oxidation
Authors: Ross G. J. , Kodama H. 
Published: August 2006

AbstractA IIb orthochlorite (brunsvigite), from the chloritic metabasalt in the Middletown Valley of Maryland, was altered to a regularly interstratified chlorite—vermiculite after four months reaction in saturated bromine water on the steambath. The artificial weathering product resembles the regularly interstratified chlorite—vermiculite in a soil in Adams County, Pennsylvania, that has developed in greenstone similar to the chloritic metabasalt in the Middletown Valley of Maryland. The results of this and previous investigations on artificial and natural weathering of chlorites indicate that oxidation of structural Fe2+ is an important reaction in the alteration of chlorites into vermiculitic products. The results also show that IIb orthochlorites, apparently structurally similar but having different Fe2+ contents may react differently under the same weathering conditions. For example the acid oxidation treatment altered a IIb chlorite (diabantite) directly into a vermiculite, whereas the same treatment altered another IIb chlorite (brunsvigite) into a regularly interstratified chlorite—vermiculite. Detailed investigations of the chlorite structures are probably necessary to determine whether or not these alteration processes are structurally controlled.
Effect of Swelling on the Infrared Absorption Spectrum of Montmorillonite
Authors: Lerot Luc , Low Philip F. 
Published: August 2006

AbstractThe i.r. spectra of mixtures of different Na-montmorillonites were determined at several water contents between 2 and 22 g of water/g of montmorillonite. It was found that Si—O absorption is represented by four closely-spaced bands, one of which is pleochroic. The pleochroic band appeared only at higher water contents. All of these bands, excepting that with the highest wave number, shifted in frequency with increasing isomorphous substitution. None of them shifted in frequency with increasing water content.The absorption coefficient for the principal Si—O absorption decreased with increasing isomorphous substitution but increased with increasing water content. Niether isomorphous substitution nor water content appeared to have any significant effect on absorption due to O—H stretching or H—O—H bending in the interlayer water.At a critical water content for each montmorillonite, an abrupt change occurred in the absorption coefficient for the principal Si—O absorption. This change was ascribed to a sudden rearrangement of the particles.
Formation of Phyllosilicates and Zeolites from Pure Silica-Alumina Gels
Authors: De Kimpe C. R. 
Published: August 2006

AbstractThe hydrothermal aging of pure silica—alumina gels in presence of 10 ml of 0.1 N sodium hydroxide solution at 175, 150 and 130°C for 8–30 days led to the synthesis of zeolites and the phyllosilicates, beidellite and kaolinite. The solution was neutralized by a partial hydrolysis of the gel which readily reorganized into a prezeolitic material. At pH values ⩾ 9, with 300 or 600 mg of gel, it evolved towards the crystalline zeolites P and S, with low surface area (7–100 m2/g) but high exchange capacity (300–475 m-equiv./100 g). With gel amounts of 600–2400 mg, and pH values of 8–5.5, the prezeolitic material provided rows of O—Si—O—Al—OH which recombined to form the phyllosilicate structures. Surface area increased (170–325 m2/g) but exchange capacity decreased (100–250m-equiv./100 g). The results obtained by various techniques (XRD, DTA, IR) indicated a moderate degree of crystallinity of these phyllosilicates; in addition, X-ray powder diffraction suggested that hk bands were the first to develop.The positive results obtained with a 0.40 ratio Al2O3 gel compared with the negative results obtained with 0.30 or 0.50 Al2O3 gels indicate that the gel composition is very important for the formation of phyllosilicates under the experimental conditions.
The Nature of TiO2 in Kaolinite
Authors: Weaver Charles E. 
Published: August 2006

AbstractSEM, TEM, and electron probe studies indicate that the anatase in Georgia kaolins, and probably anatase in general, consists of subspherical particles (TiO2 pellets) 0.05–0.1 µm dia. Some pure anatase aggregates may be pseudomorphic after ilmenite and have a tabular shape, but much of the anatase is formed from Ti that occurs as scattered ions in the octahedral sheets of biotite. When removed from the biotite this material forms TiO2 pellets. These pellets can occur as: single pellets; irregular aggregates; layered aggregates; spherical aggregates; mixed aggregates (with kaolinite); coated aggregates (with kaolinite). Physical energy can be used to break TiO2—kaolinite aggregates, separate single TiO2 pellets from kaolinite plates and remove kaolinite coatings from TiO2 aggregates.Al and Si are present in all TiO2 aggregates and the Si—Al ratio is lower in the aggregates than in the kaolinite. An amorphous Si—Al compound may be present and act as a cement.The anatase apparently is formed from Ti that is released from the parent mineral as Ti (OH)4. The Ti (OH)4 precipitates to form an amorphous hydrous oxide gel which dehydrates to form a granular aggregate of small anatase crystals.
New Approach to the Problem of the Interlayer Bonding in Kaolinite
Authors: Więckowski Tadeusz , Wiewióra Andrzej 
Published: August 2006

AbstractThe possibility of recording the absorption band which is related to oscillations of free OH in a superficial plane of the octahedral sheet of kaolinite inspired the present authors to review the problem of cohesion forces in kaolinite. Structural and spectroscopic criteria as applied to kaolinite proved that the cohesion of adjacent kaolinite layers may be estimated in terms of bent hydrogen bonds. Energy calculations were performed with the aid of a Lennard-Jones function using a modified linear model of the hydrogen bonds. The entire energy is composed of four terms described by the general potential function, van der Waals repulsion and an electrostatic attraction. The energy values of the individual terms are within the limits characteristic of each of them.
Quantitative X-ray Powder Diffraction Analyses of Clays Using an Orienting Internal Standard and Pressed Disks of Bulk Shale Samples
Authors: Cody R. D. , Thompson G. L. 
Published: August 2006

AbstractQuantitative analysis of clay minerals by X-ray powder diffraction requires oriented clays in order to increase detection limits of the analyses. This is achieved commonly either by smear or sedimentation techniques; however, these techniques can lead to poor analytical precision when used with an internal standard because they often produce non-homogeneous internal standard—clay mineral mixtures. Compaction of bulk shale material at 8000 psi in an hydraulic press produces preferred orientations comparable to that produced by smear or sedimentation. When used with a suitable platy internal standard which provides an estimate of clay mineral preferred orientation, excellent analytical precision is achieved routinely. Several lines of experimental evidence indicate that 1–5 µm MoS2 is an ideal orienting internal standard for use with compaction mounts.
Microstructure, Mineralogy and Chemistry of Cambrian Glauconite Pellets and Glauconite, Central U.S.A.
Authors: Odom I. Edgar 
Published: August 2006

AbstractGlauconite pellets in the Cambrian of the central U.S.A. frequently contain two textural forms of glauconite–aggregate and oriented—which differ in both mineralogy and chemistry. The aggregate glauconite composes the bulk of most pellets and consists of crystals in a nearly random arrangement. The oriented glauconite occurs primarily as rims on the periphery of pellets. It has a honeycomb-like structure—the crystals are oriented with their c-axes tangent to the aggregate-textured cores. Scanning electron photomicrographs show that the aggregate and oriented textures grade one into the other.The aggregate glauconite has a 1 M structure and less than 5% expandable layers, whereas the oriented form has a 1 Md structure and ∼ 10% expandable layers. The aggregate glauconite contains 5–8% more total iron oxides and 2–3% less Al2O3 than the oriented glauconite. The b-cell dimension of individual samples increases nearly linearly with increasing octahedral Fe3+ + F2+ + Mg content. Chemical and crystallographic variations among various samples are, for the most part, related to the ratio of aggregate to oriented glauconite.The transition between the texture of the aggregate and oriented glauconite suggests that some glauconite pellets may form by concretionary growth. It is proposed that Cambrian glauconite pellets grew through the repetitive development of a smectite-like clay at the margin of pellets. The smectite was later altered, both chemically and texturally, first to the oriented and then to the aggregate-textured glauconite.
Clay Mineral Stability as Related to Activities of Aluminium, Silicon, and Magnesium in Matrix Solution of Montmorillonite-Containing Soils
Authors: Weaver R. M. , Jackson M. L. , Syers J. K. 
Published: August 2006

AbstractThe influence of geomorphological site characteristics on soil clay mineral stability of montmorillonite-containing horizons of a southern Wisconsin soil catena was interpreted in terms of the solute activity function values of pSi(OH)4, pH-1/2pMg2+ and pH-1/3pAl3+ in suspensions of the separated clay fractions. Montmorillonite stability and/or formation vs that of kaolinite for the soil clays was evaluated by a plot of the solute activity functions on a three dimensional diagram derived for montmorillonite, kaolinite, and gibbsite at constant temperature (25°C) and constant pressure (one atm.). Although all the soil clays contained both montmorillonite and kaolinite, the position of the soil clay solute activity functions in the stability diagram clearly reflected the influence of the geomorphological—geochemical site conditions in which each soil horizon was developed, with corresponding differences in the SiO2/Al2O3 molar ratio of the reactive fraction. Montmorillonite stability positions of the solute activity functions were induced by soils (clays with reactive fractions with SiO2/Al2O3 molar ratios = 3–4) from calcareous or poorly drained horizons, while kaolinite stability positions of the functions were induced by soils (clays with reactive fractions of SiO2/Al2O3 molar ratios = 2) from acid, freely drained horizons.