bluuebunny/crossref_metadata_2025_split huggingface dataset:
Scan Electron Micrographs of Kaolins Collected from Diverse Environments of Origin—II
Authors: Keller W. D. 
Published: August 2006

AbstractScan electron micrographs (SEM) show the textures of ball clay, plastic refractory clay, flint clay, and of kaolins from Cornwall, U.K., and Brittany, France. The texture of ball clay is a swirl and ragged-flake pattern. Plastic refractory clay shows a transition in texture from ball clay to plastic, semi-plastic, to semi-flint, and flint-clay. Flint-clay texture exhibits a matrix of tiny, compactly interlocked clay grains in which may be interspersed small, tight books and sheaves of kaolinite. The plastic to flint clays are interpreted to be sequential components of the flint-clay facies. In one sense they represent elements in clay diagenesis.Kaolins from the Cornwall district, U.K., and Brittany, France, show more similarity than dissimilarity in texture. Evidence from texture suggests that while hydrothermal action at Cornwall initiated alteration of the granite, the last significant process of kaolinization there was weathering.
Studies on Adsorption of Telone—II: Adsorption of Telone on Montmorillonites
Authors: Singhal J. P. , Kumar Dinesh 
Published: August 2006

AbstractThe interaction of telone with acid and base saturated montmorillonite furnished adsorption isotherms which possessed combined features of H (high affinity) and C (linear rising) class isotherms; a fall in pH, an increase in electrical conductivity and formation of chloride ions. The observations were indicative of a process of chemisorption, both at the planar and lateral sites of montmorillonites, followed by penetration and swelling of the substrate micropores with telone. A reaction mechanism for the process of chemisorption has been proposed.
The Structures of Ornithine-Vermiculite and 6-Aminohexanoic Acid-Vermiculite
Authors: Slade P. G. , Telleria M. I. , Radoslovich E. W. 
Published: August 2006

AbstractFourier syntheses have been used to establish the arrangement of organic molecules in the interlamellar regions of a 16.10 Å phase of ornithine-vermiculite and a 16.92 Å phase of 6-aminohexanoic acid-vermiculite. The organic cations form two layers parallel to the silicate surfaces in ornithine-vermiculite and in 6-aminohexanoic acid-vermiculite the organic cations form ascending and descending “stairs” from the silicate sheets.Ornithine-vermiculite forms a true single layer polytype but by contrast 6-aminohexanoic acid-vermiculite is two-layered and has a true c axis of 34.09 Å. Since a two layered vermiculite was used as a starting material to prepare the organic complexes, exchangeable organic cations affect the stacking sequence of the silicate sheets.
The Birefringent Orientation and Relaxation of Clay Platelets as Affected by Particle Size, Saturating Cation and Clay Type
Authors: Schepers J. S. , Miller Raymond J. , Brown D. S. , Beavers A. H. 
Published: August 2006

AbstractAn electrooptic birefringence technique was employed to study the effect of particle size, saturating cation, and clay type on the rotational diffusion coefficient (a measure of the rate at which the particles rotate or relax within the solution) from a preferred orientation. These studies help elucidate the nature of the cation—water environment near the clay particles.Previous work has shown that some clay particles orient at both low and high voltages due to a permanent dipole and an induced dipole, respectively, whereas other clays under similar short-duration pulses orient only at high voltages. The permanent dipole was attributed to the iron in the octahedral layer of the clay mineral, whereas the induced dipole was probably due to a redistribution of the diffuse double-layer cations. This study shows that smaller clay particles orient more readily at low voltages and have greater rotational diffusion coefficients at high voltages. The higher the rotational diffusion coefficient, the faster the particles move in their surrounding water-cation environment. The effect of the saturating cation on the rotational diffusion coefficients was Na > Li > K for the permanent dipole and K > Li > Na > Ca > Mg for the induced dipole orientation. Previous results (Schepers and Miller, 1974) are interpreted to mean that a particle in dilute suspension can rotate independently of its environment only when the salt concentration in the surrounding medium approaches zero. At higher salt concentrations, or if the particle environment is perturbed by an electric field, the particle rotates with a water shell. As the concentration of salt or strength of the electric field increases further, either the viscosity of the surrounding solution increases or the size of the rotating shell is greatly increased. Thus, the water around clay particles appears to be structurally different than normal, and this condition is probably caused by the nature of the clay—cation interaction.
Clay Mineral Studies of the Lower Permian Havensville Shale in Kansas and Oklahoma
Authors: Lee Moon J. , Chaudhuri S. 
Published: August 2006

AbstractAnalyses of samples of the Havensville Shale, collected from six localities in Kansas and northern Oklahoma, showed that the distribution of clay minerals and chemical variations in the clay minerals were related to changes in the sedimentary facies. The major clay minerals assemblages were: (1) illite, mixed-layer illite—montmorillonite, and regularly interstratified chlorite-vermiculite in the shaly facies of northern and central Kansas, (2) montmorillonite, illite and mixed-layer illite-montmorillonite in the calcareous shale and algal limestone facies of southern Kansas, and (3) kaolinite, illite and mixed-layer illite—montmorillonite in the sandy facies of northern Oklahoma. Differential settling and transportation of clay detritus were the major factors in the pattern of distribution of the clay minerals. Regional differences were noted in the abundance of 2m illite polymorphs, the K/Rb ratio and the illite 001/002 intensity ratio. Some structural variations and chemical differences among the clay minerals were consequences of modifications during deposition in different environments and diagenesis.
Scan Electron Micrographs of Kaolins Collected from Diverse Origins—III. Influence of Parent Material on Flint Clays and Flint-Like Clays
Authors: Keller W. D. 
Published: August 2006

AbstractThe nature of the parent material from which flint clay or flint-like clay is derived may modify the texture of the clay as observed by SEM. Flint clays occurring in Pennsylvanian-age swamp basins into which were transported residues weathered from sedimentary country rock exhibit a texture of interlocked kaolin pockets and sheaves. On the other hand, flint clay or flint-like clay derived by weathering of volcanic ash exhibits a texture resembling, on a micro-scale, the scalloped, “oak-leaf” pattern of montmorillonite. The interpretation is that an expanding clay having a transitional role between the ash and the kaolinite is the donor source of the micro-scalloped pattern inherited by kaolinite. X-ray powder diffractograms of the clays support the interpretation.
Reduction and Oxidation of Fe3+ in Dioctahedral Smectites — 1: Reduction with Hydrazine and Dithionite
Authors: Rozenson I. , Heller-Kallai L. 
Published: August 2006

AbstractHydrazine and dithionite, both of which are strong reducing agents, react differently with various dioctahedral smectites. Both the nature of the reducing agent and the structure of the clay affect the course of the reaction. Hydrazine reduces octahedral Fe3+ efficiently if the mineral has a low tetrahedral charge. The reducing action of dithionite does not depend upon the charge.The results obtained by different physical methods of investigation suggest that reduction of iron is associated with protonation of an adjacent OH group. The Fe2+ formed is readily re-oxidised but the structural changes occurring on reduction are reversible only when Al-OH-Fe, but not when Fe-OH-Fe associations are involved. Reaction mechanisms are proposed and changes in the distribution of iron in the octahedral sites are discussed.
Reduction and Oxidation of Fe3+ in Dioctahedral Smectites — 2: Reduction with Sodium Sulphide Solutions
Authors: Rozenson I. , Heller-Kallai L. 
Published: August 2006

AbstractReaction with Na2S solutions at high pH led to almost complete, reversible reduction of iron in montmorillonite, whereas the structural iron of nontronite persisted in the ferric form. Concentrated Na2S solutions caused severe corrosion of nontronite and extracted appreciable amounts of iron, which was precipitated as sulphides. In contrast the morphology of montmorillonite was preserved and only very minor amounts of iron were extracted. These differences were attributed to the high concentration of Fe-OH-Fe groups in nontronite, which are unstable on reduction. The difference between Na2S and other reducing agents is discussed.
Interpretation of Infrared Spectra of Oxidized and Reduced Nontronite
Authors: Stucki J. W. , Roth C. B. 
Published: August 2006

AbstractInfrared spectra of nontronite reveal shifts to lower wave, number in peaks located at 3570, 1030, and 821 cm-1, which are assigned to vibrational modes for O-H stretching, Si-Ob (basal oxygens) tetrahedral vibrations, and FeO-H deformation, respectively, as the Fe2+ content increases upon reduction. A pleochroic shoulder at 1110 cm-1 resulting from Si-Oa (apical oxygens) interactions appears to be unchanged with reduction. The absorption band at 848 cm-1 shifts to higher energy with reduction of structural iron, and persists at 840 cm-1 after complete deuteration of structural hydroxyls. The band is assigned to a Fe-OH mode where the OH moves as a unit. The shift in the Si-Ob mode to lower vibrational energy with reduction may indicate a decrease in stress forces between the tetrahedral and octahedral sheets.
The Surface Reactivity of Vermiculite Towards Hexamethylene Diisocyanate (HMDI)
Authors: Siffert B. , Biava H. 
Published: August 2006

AbstractThe reaction of hexamethylene diisocyanate with the surface of heat-activated vermiculite parallels the reactions with the oxides SiO2, Al2O3, MgO considered individually, which a number of authors have already described. The fixation ratio is about 5 molecules per 100 Å2 area. Nearly one half of the grafted molecules retain a “free” isocyanate function, which is requisite for a subsequent polyaddition of the processed mineral. The interaction with vermiculite occurs according to three principal processes; (i) formation of a surface urethane, (ii) formation of a surface carbamate, (iii) fixation by hydrogen bonds.
Interaction of Petroleum Heavy Ends with Montmorillonite
Authors: Clementz David M. 
Published: August 2006

AbstractAdsorption of asphaltenes and resins onto montmorillonite occurs rapidly and to a large extent irreversibly under near-anhydrous laboratory conditions. Factors which influence the adsorption are the exchangeable cation on the clay, the basic nitrogen components of the molecules, and the solvent. As a result of this adsorption, the physical and chemical properties of the clay are drastically altered. The fundamental principles revealed in this study lead to a better understanding of the physical and chemical behavior of clays in petroleum reservoirs.
The “Layer Charge” of Regular Interstratified 2:1 Clay Minerals
Authors: Lagaly G. 
Published: August 2006

AbstractAlkylammonium ion exchange on mixed-layer minerals gives detailed information about the variation of cation density in succeeding interlayer spaces. Three mixed layer samples from Japan (supplied by Dr. H. Kodama) were investigated. Their nearly 1:1 interstratification is based on regularly alternating high- and low-charged interlayer spaces, which are caused by a regular sequence of polar layers. The cation density in the high-charged interlayer spaces is >0.8 eq/(Si, Al)4O10. The low-charged interlayer spaces have an average cation density of 0.4 eq/(Si, Al)4O10 and heterogeneous charge distribution. The kind of heterogeneity of the Goto Mine sample differs from that of the Yonago Mine and the Honami Mine samples.The Goto Mine specimen has a rather regular sequence of the low- and high-charged interlayers in proportions close to 0.50:0.50. The other two samples contain interlayer spaces with pronounced unsymmetrical charge distribution. The Yonago Mine sample probably has in random distribution with the polar layers about 10% mica-like layers segregated to packets of three and more layers; the ratio of high-charged interlayers to the low-charged ones is increased to about 0.55:0.45. The Honami Mine sample probably contains isolated mica-like layers or pairs of them. The proportion of the high-charged interlayers is estimated to be about 0.53:0.47 and is lower than determined by Kodama from the glycerolated sample.The samples investigated may be considered as end-members of a series of interstratified specimens which begins with smectites with mixed-layer like charge distribution.
Behavior of Kaolinite Pellets at Elevated Temperatures
Authors: Flank W. H. 
Published: August 2006

AbstractDimensional changes in kaolinite pellets as a function of temperature show two sharp shrinkage “steps,” at about 450–550°C and 900–980°C, which are roughly comparable in magnitude. Isothermal heat-soaking tests confirm that the rates for both are kinetically controlled. Water vapor inhibits shrinkage at low temperature but promotes shrinkage at high temperature. Both the former reaction, related to dehydroxylation, and the latter reaction, related to “mullitization,” take place at temperatures well below those observed in DTA, TG, and other measurements, indicating that bond-breaking is a necessary prelude to transitions at higher temperatures.Bonding energy changes, as measured by X-ray fluorescence shifts, were used in interpreting the phenomena involved. The relative absence of bonding energy changes in the aluminum until the range 950–1100°C, and the presence of such changes in the silicon, suggest that high-temperature energy release is probably related to segregation or crystallization of silica, rather than of an aluminum-containing phase. Caution must be used in interpreting bonding energy changes, and in distinguishing kinetic and thermodynamic contributions to dynamic phenomena.
The Interaction Between Roundup (Glyphosate) and Montmorillonite. Part I. Infrared Study of the Sorption of Glyphosate by Montmorillonite
Authors: Shoval S. , Yariv S. 
Published: August 2006

AbstractThe reaction between the herbicide “Roundup,” (PAH)3G, which is the commercial name of the iso-propylammonium salt of glyphosate (H3G, N-phosphonomethyl glycine), and montmorillonite was studied. The adsorption of the anionic component of Roundup glyphosate anion, G−3, from an ethanol solution is achieved by repeated immersion of the clay film in the alcohol solution followed by drying for 6–12 hr after each immersion. During the adsorption process the surface acidity of the interlayer space must be sufficiently high to protonate the anion. A zwitterion glyphosate is thereby formed in the interlayer space. Association forms are obtained in the interlayer space in which the COOH and the PO3H groups are linked to the exchangeable cations through water bridges. Adsorption of the glyphosate anion from aqueous solution of Roundup occurs when this anion forms a neutrally or positively charged complex with the exchangeable cation. This may occur with Al- and Fe-montmorillonite, when the molar ratio glyphosate:metal is such that a complex with a 1:1 ratio can be formed in the interlayer space. To clarify the reaction mechanism, adsorption of glycine by montmorillonite from ethanol solution was also studied. The associations obtained between glyphosate and exchangeable cations are less variable than those obtained between glycine and exchangeable cations in the interlayer space of montmorillonite. The following species of adsorbed glycine were identified: glycinium cation, zwitterion glycine, glycine complexed with metal cations either as a monodentate or as a bidentate ligand. In the latter case a chelate is formed.
The Release of Aluminum from Aluminosilicate Minerals. II. Acid-Base Potentiometric Titrations
Authors: Cabrera F. , Talibudeen O. 
Published: August 2006

AbstractAcidified suspensions of Al-saturated kaolinite, montmorillonite, mica, illite, and biotite in 10−3 M NaNO3 were potentiometrically titrated with 0.1 N NaOH and 0.1 N HNO3 in succession in a CO2-free nitrogen atmosphere. The resulting curves were compared with those for Al(NO3)3 solutions of similar Al concentration in the supernatant solution and corrected for Al in the entrained solution in the clay.Base titrations of Al ions adsorbed on all the minerals, except montmorillonite, showed two pH inflections separated by a buffering range. With montmorillonite, there were three pH inflections similar to those for Al in solution. The first inflections in the titration of suspensions occurred at lower pHs and were less pronounced than for Al in solution. These represent the titration of H3O+ sorbed during the pretreatment. The buffering by adsorbed Al ions is also less than that by Al in solution.The OH− used up by adsorbed Al ions between the first and last inflections was equal to, or slightly greater than, the CEC of the minerals, except for mica where it was more than twice the CEC, because new interlayer surfaces were formed during the acid pretreatment. Acid titration curves of Al ions in the adsorbed and solution states showed hysteresis when related to the base titration curves. The use of two titration speeds (3 and 0.3 pH units/hr) only slightly affected the titration curves of the minerals suggesting that the observed effects were not caused by lack of equilibrium with added base or acid.
High Surface Area Solids Obtained by Reaction of Montmorillonite with Zirconyl Chloride
Authors: Yamanaka S. , Brindley G. W. 
Published: August 2006

AbstractExchange reactions of Na-montmorillonite with zirconyl chloride solutions give products with basal spacings near 18 Å which are stable to 500°C and have surface areas of the order of 300–400 m2/g. The Na ions are exchanged with tetrameric hydroxy cations [Zr4(OH)14•nH2O]2+. The high surface area is attributed to the porosity formed by stable zirconium oxide “pillars” formed by dehydroxylation of the complex cation. The nitrogen adsorption isotherms are of Langmuir type and are consistent with adsorption in interlayer micropores. Reduced-charge montmorillonites, formed by application of the Hofmann-Klemen procedure, give either similar or slightly smaller surface areas.
Ideal Behavior in Na+-Trace Metal Cation Exchange on Camp Berteau Montmorillonite
Authors: Sposito Garrison , Mattigod Shas V. 
Published: August 2006

AbstractThe conditions under which an exchanger phase will behave as an ideal mixture are established from thermodynamic principles. It is shown that, if a stoichiometric cation-exchange reaction is reversible, the exchanger phase will exhibit ideal behavior if the Vanselow selectivity coefficient is independent of the exchanger composition. This criterion is applied to some recently published data for Na+-trace metal cation exchange on Camp Berteau montmorillonite. An analysis of the data suggests that, so long as the exchange process is reversible, Na+-trace metal cation exchange produces an exchanger phase that behaves as an ideal mixture.
Reactivity of Adsorbed and Structural Iron in Hectorite as Indicated by Oxidation of Benzidine
Authors: McBride M. B. 
Published: August 2006

AbstractThe roles of different forms of Fe(III) impurities in a hectorite with respect to the oxidation of benzidine in aqueous suspension have been evaluated using electron spin resonance and UV-visible spectroscopy. Natural surface-adsorbed Fe(III) showed no detectable activity in the oxidation process, while very small quantities of structural octahedral Fe(III) apparently promoted a relatively rapid conversion to the radical cation. However, extremely small quantities of benzidine were oxidized in comparison to the exchange capacity of the clay. Freshly adsorbed Fe3+ cations effectively oxidized benzidine, but lost much of this ability upon aging. The Fe(III)-benzidine electron transfer could be distinguished from an O2-benzidine reaction, since the latter reaction was slow and limited by the rate of O2 diffusion into the clay-water system. The O2-benzidine reaction was also inhibited at high pH. The existence of two reaction mechanisms and the involvement of only a small fraction of the total structural iron, as shown by comparison of the hectorite and a montmorillonite, may explain the conflicting interpretations in the literature. The benzidine blue reaction not only requires an oxidizing agent to form the radical, but also a clay surface to adsorb and stabilize it against further oxidation.
Cation Ordering Pattern in Amesite
Authors: Hall Stephen H. , Bailey Sturges W. 
Published: August 2006

AbstractCation ordering in amesite-2H2 from Antarctica has reduced the true symmetry from the ideal hexagonal space group P63 to triclinic P1. All crystals show 6-fold biaxial twin sectors on (001), and the twinned crystals produce an average diffraction symmetry that is hexagonal. Individual twin sectors cut from the larger aggregate have 2 V optic angles near 18°, slightly monoclinic unit-cell geometry, and triclinic diffraction symmetry. Structural refinement of an untwinned sector in subgroup symmetry shows nearly complete ordering of Si,Al in tetrahedral sites and of Mg, Al in octahedral sites.In triclinic symmetry the two layers in the unit cell are no longer equivalent. Tetrahedra lying on the pseudo-63 screw axis are alternately Si-rich and Al-rich in adjacent layers. Of the three octahedral sites in each layer, one is smaller than the other two and is interpreted as Al-rich. The distribution of Al-rich and Mg-rich octahedra violates both the pseudo-3-fold rotation axis within each layer and the pseudo-63 screw axis that relates one layer to the next in the ideal space group. Local charge balance is achieved in adjacent layers by location of all tetrahedral and octahedral Al in lines parallel to X1 and spaced at intervals of b1/2. Similar charge balance patterns parallel to X2 and X3 are postulated to account for the sector twinning, which has been observed also in amesites from Chester, Massachusetts, USA, Saranovskoye, USSR, and Postmasburg, South Africa.
The Hydrothermal Transformation of Sepiolite to Stevensite and the Effect of Added Chlorides and Hydroxides
Authors: Güven Necip , Carney Leroy L. 
Published: August 2006

AbstractHydrothermal reactions in the system sepiolite/H2O have been examined between 149° and 316°C. Approximately 10–20% of the starting sepiolite was converted to a smectite (stevensite) at 204°C within 24 hr. Similar results were obtained when CaCl2, NaOH, Ca(OH)2, or Mg(OH)2 was added to the system. In the presence of NaCl, about 60% of the sepiolite was converted to stevensite, whereas, only 5% stevensite formed in the presence of MgCl2. Greater amounts of stevensite formed at 260°C in these systems. Above 316°C, 60–80% of the sepiolite was converted to stevensite in 24 hr, regardless of the presence or absence of salts. Within the experimental conditions used, temperature is the most important factor in the sepiolite-to-stevensite conversion.At or below 216°C, sepiolite appears to transform into stevensite by dislocations involving c12 glides that are triggered by the stresses of the hydrothermal conditions. Above this temperature, stevensite seems to form by direct precipitation after dissolution of sepiolite.