bluuebunny/crossref_metadata_2025_split huggingface dataset:
Crystal Nucleation and Growth in Hydrolysing Iron(III) Chloride Solutions
Authors: Atkinson R. J. , Posner A. M. , Quirk J. P. 
Published: August 2006

Abstract0.5 molal iron(III) chloride solutions were hydrolysed at room temperature by base additions in the range OH/Fe mole ratio 0–2.75. After an ageing period the hydrolysed solutions were used to produce amorphous hydroxide gels from which crystalline products were grown at 65°C, at low pH or high pH. Examination of crystal composition and morphology and comparison with similarly treated nitrate solutions showed that the nucleation of hematite and goethite is inhibited in chloride containing solutions, which allow growth of small rod shaped β-FeOOH to predominate or occur exclusively in gels at pH 1–2. The addition of seed crystals of hematite and goethite allows competitive growth of all three minerals. The transformations β-FeOOH → α-Fe2O3 and β-FeOOH → α-FeOOH at pH 1–2 proceed by dissolution and reprecipitation and are promoted by adding seed crystals.
A Comparative Study of Thermal Effects on Surface and Structural Parameters of Natural Californian and Quebec Chrysotile Asbestos up to 700°C
Authors: Murphy William J. , Ross Robert A. 
Published: August 2006

AbstractThe effect of heat treatment on surface area, pore volume, pore size distribution, physical and chemical structure up to 700°C have been studied on samples of naturally occurring chrysotile minerals from California and Quebec. Techniques used included thermogravimetric analysis, low-temperature nitrogen adsorption, electron microscopy, X-ray powder and electron diffraction. The materials behaved similarly on heating to 100°C showing a 0.5% weight loss attributable to desorption of physisorbed water. At 500°C, Quebec samples retained the chrysotile crystal structure while Californian samples were X-ray amorphous. Forsterite was formed by dehydration of both chrysotiles at 700°C; the greater stability of the Quebec samples to this process is explained by the presence of brucite as an impurity which enters into stray solid-solid interactions with the chrysotile.
Gas Chromatographic Pathways for Certain Chloro-Alkylammonium Montmorillonites
Authors: McAtee James L. , Harris Brent R. 
Published: August 2006

AbstractA series of chloro-alkylammonium montmorillonites was produced by cation exchange from Na+-montmorillonite. Gas chromatographic data were obtained for light hydrocarbons and certain oxides of nitrogen. Surface area and X-ray powder diffraction studies were made on each organo-clay, making possible differentiation between possible chromatographic pathways. Adsorption of the gas molecules on the silicate sheet was determined to be the dominant chromatographic pathway for all gases studied.
X-Ray Study of the Interlayer Region of a Barium-Vermiculite
Authors: Telleria M. I. , Slade P. G. , Radoslovich E. W. 
Published: August 2006

AbstractAn X-ray diffraction analysis of a barium-vermiculite shows it to have a triclinic unit cell with the following dimensions a = 5.33, b = 9.26, c = 12.47 Å, α = 100.75°, ß = 93.5° and γ = 90°. The proposed structure, adjusted in space group Cl, has the exchangeable cations approximately over the ditrigonal holes of the silicate surface and on either side of a hexagonal network of water molecules extending over the middle of the interlamellar region. The interlayer material imposes a relative displacement of ± b/4 on adjacent silicate sheets. The importance of these displacements, not previously found in layer silicates, is emphasized.
Azobenzene Intercalates of Montmorillonite
Authors: Adams J. M. , Reid P. I. 
Published: August 2006

AbstractA study has been made of the interaction of azobenzene vapor with a series of cation-exchanged montmorillonites. Cu2+- and Ag+-clays give basal spacings ≥ 20Å. The azobenzene retains its trans conformation in the clay and can be extracted with ether. If the intercalate is heated above 120°C then there is catalytic decomposition leaving a black product. Infrared spectra of an extract from this product suggests that it might be made up of a mixture of amines. A photo-electron spectroscopic study shows that the nitrogen is in two distinct chemical environments both in the initial and in the blackened intercalates. The C:N ratio remains at 6:1 throughout.
Synthesis and Swelling Properties of Saponites with Increasing Layer Charge
Authors: Suquet H. , Iiyama J. T. , Kodama H. , Pezerat H. 
Published: August 2006

AbstractNine synthetic Na-saponites with charge densities varying between 0.33 and 1.0 have been prepared. Their swelling properties and structural organization in water, ethylene glycol and glycerol show discontinuities in the physico-chemical behaviour of these samples. The layer charge densities caused changes in swelling properties and structural organization of the minerals. These changes also depended upon the nature of the solvation liquid and the interlayer cation involved.Electron diffraction patterns of the Ba-saponites showed no abnormal diffusion making honeycomblike patterns between Bragg reflections.The results indicate criteria for estimating the layer charge of tetrahedrally substituted trioctahedral 2/1 phyllosilicates.There is no upper limit until x = 1 for the layer charge x which is specific to the smectite-group. Consequently, the changes in the swelling properties observed when x = 0.5-0.6 and x = 0.8-0.9 come from the modifications of the interlayer structure, which are mainly a function of cation-liquid and silicate layer-liquid interactions. Consequently, there is an overlap between the saponite and the vermi-culite mineral groups.
Properties and Quantitative Estimation of Poorly Crystalline Components in Sesquioxidic Soil Clays
Authors: Fey M. V. , Le Roux J. 
Published: August 2006

AbstractSesquioxidic soil clays from Oxisols in South Africa, Australia and Brazil, and two clays from Andosols in Japan and New Zealand, were investigated by selective dissolution techniques. Acid ammonium oxalate (pH 3) was found to be superior to currently popular alkaline reagents for extracting amorphous aluminosilicates and alumina from these clays. Boiling 0.5 N NaOH dissolved large amounts of finely-divided kaolinite and halloysite, while hot 5% Na2CO3 reaction was too slow (partial dissolution of synthetic amorphous aluminosilicates with one extraction) and insufficiently selective (gibbsite and kaolin of poor crystallinity dissolve to a variable extent). On the other hand, synthetic gels (molar SiO2/Al2O3 ranging from 0.91 to 2.55) dissolved completely after 2 hr shaking in the dark with 0.2 M acid ammonium oxalate (0.2 ml/mg). Specificity of oxalate for natural allophane was indicated by removal of similar quantities of silica and alumina using different clay:solution ratios. Oxalate extraction data indicated that allophane is absent in Oxisol clays. Allophane was determined quantitatively in volcanic-ash soil clays by allocating hydroxyl water content to oxalate-soluble silica plus alumina on the basis of an ignition weight loss-chemical composition function for synthetic amorphous alumino-silicates. Parameters of chemical reactivity and distribution of electric charges following various chemical pretreatments of allophane were found to correspond closely to those predicted on the basis of synthetic gel behaviour. Results for Oxisol clays suggested that the role of amorphous (oxalate-soluble) alumina in governing physicochemical properties is generally less than that of the poorly-crystalline, Al-substituted iron oxide component which is removed by deferration with citrate-dithionite-bicarbonate reagent.
On the Evaluation of Nutrient Pools of Forest Soils
Authors: Thompson Graham R. , Behan Mark , Mandzak John , Bowen Chris 
Published: August 2006

AbstractThe standard method of assessing the available portion of the nutrient reservoir of a forest soil is to use a neutral salt solution, such as NH4OAc, to extract the exchangeable plus dissolved ions, which are analyzed and considered available. This approach, designed for evaluating nutrients available for the short growth term of agricultural crops, is inadequate for assessing the nutrient pool of forests where tree growth term may reach 100 yr or more.Soil nutrient reservoirs were evaluated in two forest soils for K, Na, Ca, Mg and Fe, using an approach based on continuous extraction of the elements and kinetic analyses of the extraction rate curves. The analyses of the curves indicate that K, Na, Ca and Fe are each released at four separate
constant rates, and Mg is released at three separate constant rates. By analogy with similar kinetic studies done on monomineralic layer silicate samples, each separate extraction rate is thought to correspond to a single type of bond site in the soil. Higher extraction rates indicate greater ease of removal and are interpreted as indicating a higher degree of availability relative to the extractant.The available K reserves of the Everett soil evaluated by standard methods, compared with annual net K uptake rates of its forest system, indicates growth limiting K deficiency in 12–17 yr. K availability assessed by kinetic analyses indicates about 100 yr supply of K is available.
Qualitative and Quantitative Study of Stacking Faults in a Hydrazine Treated Kaolinite—Relationship with the Infrared Spectra
Authors: Barrios J. , Plançon A. , Cruz M. I. , Tchoubar C. 
Published: August 2006

AbstractArtificial stacking faults can be created within a well-crystallized kaolinite by intercalating and removing hydrazine. X-ray powder patterns with electron microscopy show that the created defects are ±b/3 translations with a proportion 0.30. The infrared spectrum of the treated kaolinite is not modified with respect to the starting one. On the other hand, a natural kaolinite containing defects by displacement of Al vacancies in a similar proportion shows an infrared spectrum significantly different from that of a well-crystallized kaolinite. The modification of the infrared spectra of natural disordered kaolinites is then related to the presence of defects by change of Al vacancy positions
A Study of the Adsorption of Ni(II) and Cu(II) by Clay Minerals
Authors: Koppelman M. H. , Dillard J. G. 
Published: August 2006

AbstractThe adsorption of Ni(II) and Cu(II) on to the clay minerMs kaolinite, chlorite, and illite has been investigated. The quantity of Ni(II) at pH 6 and Cu(II) at pH 5 adsorbed has been found to vary in the manner chlorite > illite > kaolinite. Examination of the mode of bonding of the metal ions to the clay minerals using X-ray photoelectron spectroscopy (XPS) has been carried out. Comparison of the binding energies for metal ions in octahedral sites in selected minerals (reference minerals) and in simple nickel and copper containing compounds with values for Ni(II) and Cu(II) adsorbed on chlorite indicate that nickel(II) is probably bound as the aquo ion while copper(II) may be adsorbed as Cu(OH)+.
Selectivity and Adsorption Capacity of Smectite and Vermiculite for Aluminum of Varying Basicity
Authors: Veith J. A. 
Published: August 2006

AbstractSmectite (from South Dakota, Wyoming, and Mississippi) and Vermiculite (Transvaal) were treated with solutions of Al(OH)B(3-B)+, with B varying from 0 to 2.5. The average basicity (OH/Al = B) of the Al adsorbed differed very much from the basicity of the Al added. The average basicity of the Al adsorbed by smectite was always above the average basicity of the Al added. In contrast to smectite, Vermiculite adsorbed smaller hydroxy-Al complexes. One reason for the different selective behavior was the difference in expansion between smectite (about 18 Å) and vermiculite (about 14 Å). Because of the adsorption of the relatively more basic OH-Al by smectite, smectite adsorbed considerably more Al than vermiculite. The total amount of aluminum in the interlayer generally could not be calculated by the difference between Al added and that remaining in solution after the reaction because of possible protonation of the clay mineral and adsorption of structural Al and other cations, which is more pronounced for vermiculite. The results in the present study demonstrated that neither the quantitative nor the qualitative composition of an Al(OH)B-treated exchanger can be deduced from B of the Al salts added. These points are frequently overlooked when cation exchangers are pretreated with Al of variable basicity and are used for further investigations, such as studies of CEC, surface area, interlayer spacing, anion reactions, the formation of gibbsite, etc. Before these kinds of investigations are conducted employing the pretreated OH-Al-exchangers, their composition should be known precisely.
Synthesis of Iron Layer Silicate Minerals under Natural Conditions
Authors: Harder Hermann 
Published: August 2006

AbstractThe low temperature synthesis of iron silicate minerals with clay structures is possible at surface temperatures only under reducing conditions. Under oxidizing conditions clay minerals could not be synthesized. Instead quartz and quartzine were found in these X-ray amorphous Fe III hydroxide-silica precipitates after 14 days at low temperatures (20° and 3°C) as well as geothite or X-ray amorphous iron hydroxides. Only from solutions containing Fe-II could the different iron-containing clay minerals be built up within days at low temperatures. The presence of Fe-II enables an octahedral layer of the brucite-gibbsite type to be formed. This is necessary for the bidimensional orientation of SiO4-tetrahedra leading to clay mineral formation. The presence of Fe2+- and/or Mg2+-ions is necessary for the formation of the Al3+- and Fe3+-containing octahedral layers. The reducing conditions were obtained in the experiments by addition of dithionite. With a high content of silica (ca. 20 ppm SiO2,7 ppm Fe) nontronite and lembergite, the di-Fe-III and tri-Fe-II octahedral, three-layer silicates, were built up in several days at low temperatures. With a lower silica content, that is, a lower Si/Fe ratio (15 ppm SiO2 and 20 ppm Fe), the two-layer silicate minerals greenalite and chamosite could be synthesized. A higher Mg content and more reducing conditions in the solutions favored the tri- as well as dioctahedral chamosite synthesis.The conditions of formation of recent naturally formed nontronite fit well with the synthesis conditions. Chamosites in sedimentary iron ores are characterized by a low content of SiO2, between 15–30% SiO2. This low content of silica cannot be the result of primary precipitation from seawater. The iron and silica ratio in seawater or in river waters would lead to a precipitation of ~60% SiO2 in the iron hydroxide precipitates. A probable origin for chamosite iron ores, which explains the low SiO2 content, is diagenesis of the lateritic weathering crust. Indeed, investigations of recent tropical shoreline sediments and in particular their trace element content confirm that chamosite minerals have formed diagenetically from lateritic particles in reducing sediments.
Cross-Linked Smectites. II. Flocculation and Microfabric Characteristics of Hydroxy-Aluminum-Montmorillonite
Authors: Lahav N. , Shani U. 
Published: August 2006

AbstractCross-linking of Li-montmorillonite by hydroxy-aluminum oligomers was performed in a specially constructed mixing apparatus. Observations on flocculation and solution composition were carried out during and after the cross-linking reaction; the dry product was studied by scanning electron microscopy.Flocculation was most pronounced at Al/montmorillonite ratios between 0.98 and 2.45 mM/g; below and above this range, flocculation was much less intensive. These observations can be explained by heterocoagulation and protecting colloid action. A complete neutralization of the montmorillonite charge was estimated at 1.9 mM adsorbed Al per g clay, and in order to account for the electrical charge of the hydroxy-Al, polymers with an average charge of 0.5 per Al atom must be assumed on the montmorillonite surface. Assuming that the hydroxy-aluminum form in the unreacted solution is Al6(OH)3+12, the adsorbed polymer will be Al24(OH)12+60. Alternatively, assuming Al6(OH)3+15 in the unreacted solution, this form will remain unchanged upon adsorption onto the montmorillonite surface.Differences in the microfabric of dry Al-CLM as a function of Al/montmorillonite ratio can be explained along the lines of the interpretation of the flocculation studies.
Characterization of the Particle Size and the Crystallinity of Certain Minerals by IR Spectrophotometry and other Instrumental Methods—II. Investigations on Quartz and Feldspar
Authors: Hlavay J. , Jonas K. , Elek S. , Inczedy J. 
Published: August 2006

AbstractInfrared spectra of two minerals; Urkut quartz (Hungary) and a Swedish feldspar, of different origin with different physical characteristics and crystallinity were studied. Samples were taken after appropriate grinding, and infrared spectra, X-ray powder diffraction and water vapor absorption measurements were made along with electronmicrographs. Quantitative conclusions were drawn from changes of particle size and the ratio of bands of the Si—O groups and also the degree of crystallinity and changes of the particle size, respectively.
Intercalation of Salts in Halloysite
Authors: Carr R. M. , Chaikum N. , Patterson N. 
Published: August 2006

AbstractSeveral new salt intercalation complexes of halloysite have been prepared and characterized using X-ray powder diffraction techniques taking into account both the position and the shape of the d001 peaks. The amount of intercalated ion in some fully complexed halloysites has been directly determined using conventional analytical techniques. The results show that less than half of the theoretical amount of salt is intercalated into the clay; the amount of salt depending on its nature and, where hydrolyzable ions are present, on the pH. Infrared spectra taken of some complexes give an indication of the nature of the interaction within interlayer space and elsewhere. The interactions are weak and are either dipolar attractions or hydrogen bonds. The ions which show the greatest tendency to intercalate with halloysite are water structure-breaking cations or hydrogen-bonding anions.
Flint-Clay Facies Illustrated within One Deposit of Refractory Clay
Authors: Keller W. D. 
Published: August 2006

AbstractThe flint-clay facies, originally proposed from widespread stratigraphie evidence, is represented by four of its six members within a single commercial deposit of Cheltenham refractory clay in Missouri. Scan electron micrographs show progressive changes in texture from plastic refractory clay (as in ball-clay “swirl” texture) through semi-plastic, semi-flint, to typical flint clay (recrystallized, well-ordered kaolinite). Micrographic evidence supports the interpretation of the origin of the Cheltenham clay earlier made from field and macroscopic evidence. Source material from nearby residual, weathered clay was transported into paludal basins, “digested,” partly recrystallized to kaolinite, brecciated and reconsolidated, essentially completed before being covered by younger Pennsylvanian-age sediments.
The I.R. Spectra of Dimethyl Sulfoxide Adsorbed on Several Cation-Substituted Montmorillonites
Authors: Garwood G. A. , Condrate R. A. 
Published: August 2006

AbstractThe i.r. spectra (4000-1200 cm-1) are obtained for several homoionic montmorillonite films on which various amounts of dimethyl sulfoxide (DMSO) were adsorbed. Analyses of these spectra indicate that H- and natural-montmorillonite-DMSO complexes contain an intercalated layer of physisorbed DMSO while transition metal cation substituted-montmorillonite-DMSO complexes possess both physi- and chemisorbed DMSO in their interlamellar spaces. The latter species involve coordination of DMSO molecules with the exchangeable cations by their oxygen atoms. Most of the interlamellar water is replaced by DMSO as the latter molecules penetrate the interlamellar spaces. Heat-treating transition metal cation substituted-montmorillonite-DMSO complexes at 120°C for 48 hr results in both the desorption of physisorbed DMSO and the retention of intercalated monolayers involving DMSO-transition metal cation coordination. A water-sensitive, reversible color change (tan to light purple) is produced by either desiccating over P2O5 or heat-treating at 120°C the cobalt-montmorillonite-DMSO complex. Interpretation of the visible spectra suggests that Co2+-cations undergo changes from octahedral to tetrahedral coordination during desiccation or heating. Band assignments are made for the clay complexes using the assignments for related gases, liquids, and crystals.
The Exchange of Alkylammonium Ions on Na-Laponite
Authors: Vansant E. F. , Peeters G. 
Published: August 2006

AbstractThe exchange of various alkylammonium cations from aqueous solution by sodium laponite has been studied. The affinity of the clay for these organic cations was linearly related to the molecular weight, molecular size or chain length of the alkylammonium ions. The affinity for the clay increases regularly with increasing chain length of the primary amines. A comparison of primary, secondary, and tertiary amines, containing the same alkylgroups shows that the affinity increases in the order R1NH3+ < R2NH2+ < R3NH+. These affinity sequences were attributed to important van der Waals contributions and changes in ion hydration states. The thermodynamic excess function, ΔGmE, was calculated and indicated that with respect to the pure homoionic forms the heterogeneous Na+-alkylammonium surface phases were more stable than they would be if the mixing were ideal.
The Adsorption of N-Aliphatic Alcohols from Dilute Aqueous Solutions on RNH3-Montmorillonites. Part I. Distribution at Infinite Dilution
Authors: Stul Michel S. , Maes André , Uytterhoeven Jan B. 
Published: August 2006

AbstractThe adsorption of butanol, hexanol, and octanol on alkylammonium clays of different chain length is studied. The adsorption at infinite dilution compares to the distribution of alcohol between alkane and water in bulk solution. The interlamellar phase of the montmorillonite acts as a solvent even more reactive than carbon tetrachloride. Hydrogen bonds probably occur between the OH group of the alcohol and the NH3+ group. The exchange of water by alcohol on the interlamellar alkylammonium ion is the major factor in the transfer process.
Reaction Series for Dioctahedral Smectites
Authors: Eberl Dennis 
Published: August 2006

AbstractSeveral dioctahedral clay minerals are related through reaction series. These series can be produced hydro-thermally from beidellite gel and montmorillonite by making simple changes in interlayer and solution chemistry. The series are:
gel-K-beidellite-random illite/smectite-K-rectorite-illiteK-montmorillonite-K-rectorite-illiteNa-montmorillonite or beidellite-Na-rectorite-paragoniteLi-montmorillonite-Li-tosudite-Li-rectorite-cookeite(?)Mg-montmorillonite-Mg-rectorite-tosudite-sudoite(?)Ca-montmorillonite-Ca-rectorite-margarite(?)Al-Ca-montmorillonite-kaolinite/smectite-kaolinite (150°C)Al-Ca-montmorillonite-pyrophyllite/smectite-pyrophyllite (320°C).Assuming stability for the mixed-layer phases, paragenesis is a function of P, T, and X conditions. If the phases are considered to be metastable, paragenesis is a function of the speed and path of reaction.
Dissolution of Smectites in Hydrochloric Acid: II. Dissolution Rate as a Function of Crystallochemical Composition
Authors: Novák I. , Číčel B. 
Published: August 2006

AbstractA correlation was made of crystallochemical data from 15 smectites with the half time of dissolution (t05) in 6 N hydrochloric acid at 96°C. From this the relationln t05 = 3.95 - 1.96 FeVI - 2.30 MgVIwas developed. It shows a remarkable dependence of the apparent dissolution rate of the octahedral layer of the smectites on the substitution of Fe3+ and Mg2+ for Al+3 in the octahedral position.