Interlayer Space Of Montmorillonite Research Articles

Reactions of Polynuclear Hydroxyaluminum Cations with Montmorillonite and the Formation of a 28-Å Pillared Complex: Reply

Polynuclear hydroxy-Al cations were prepared by partially neutralizing dilute solutions of aluminum chloride. These cations were introduced in the interlayer space of montmorillonite by cation exchange, which formed heat-stable pillars between the silicate layers. Polynudear hydroxy-A1 was pref- erentially adsorbed on montmorillonite compared with monomer-A1; the maximum amount adsorbed was ~ 400 meq/100 g of montmorillonite. Of this amount 320 meq was non-exchangeable. The 001 X-ray powder diffraction reflection of the polynuclear hydroxy-Al-montmoriUonite complex was at 27/k, with four additional higher-order basal reflections, giving an average d(001) value of 28.4 A. This complex was thermally stable to 700~ An analysis of the basal reflections by the Fourier transform method indicated that the 28-A complex had a relatively regular interstratified structure of 9.6- and 18.9-A component layers with a mixing ratio of 0.46:0.54. This ratio implies that the hydroxy-A1 pillars occupied every second layer. Considering the relatively small amount of A1 adsorbed and the thermally stable nature of the structure, the hydroxy-A1 pillars must have been sparsely but homogeneously distributed in the interlayer space.

モンモリロナイト層間へのニッケル水酸化物挿入反応過程における回折Ｘ線強度の変化

The X-ray diffraction intensity corresponding to the basal plane reflections, from (001) to (005), for nickel intercalated montmorillonite was measured as a function of nickel content. The intensity of these five lines changed systematically as the nickel content increased. On the other hand, the composition-dependence of the line intensity was theoretically calculated on the basis of the structure model that nickel hydroxide monolayar fills gradually in the interlayer space of montmorillonite on the various steps of intercalation reaction. The experimental results were found to be consistent with the calculated intensity. However, some differences were also found, which was discussed in terms of adsorption site difference of nickelions.

Interaction of dexamethasone and montmorillonite — Adsorption-degradation process

The degradation of dexamethasone in an aqueous suspension of montmorillonite seems to be the result of two apparent first order reactions. The dexamethasone content, as determined by high-pressure liquid chromatography (HPLC), rapidly decreases from 50 to 4.7 μg/ml after 24 h, and then remains almost constant during 168 h. The first stage of the decomposition is mainly consistent with an adsorption process, while the second one is characterized by a slow degradation of dexamethasone remaining in solution. X-ray diffraction (XRD) and infrared (IR) studies showed the presence of dexamethasone molecules adsorbed in the interlayer space of montmorillonite, with the basal spacing being consistent with an orientation of the plane of the rings parallel to that of the silicate sheets. Desorption studies showed a slow release of the dexamethasone from the interlayer space of montmorillonite.

Properties of Organo-Mineral Complexes Formed by Different Addition Sequences of Hydroxy-Al, Montmorillonite, and Tannic Acid

AbstractA study was carried out on the influence of the sequence of addition of montmorillonite, hydroxy-Al ions, and tannic acid ([Al] = 0.015 M; 6 mmole Al/g of clay; tannic acid/Al molar ratio = 0.1) on the nature of organo-clay complexes formed at pH 4.5. A negligible amount of tannate was held on the clay surfaces in the absence of Al, whereas in the presence of Al, hydroxy-Al-tannate species were easily adsorbed on clay surfaces. Their distribution on the external surface and in the interlayer space of montmorillonite, however, was a consequence of how the components reacted with each other. The complexes showed broad X-ray powder diffraction peaks at 15.6 to 19.2 Å at room temperature. They also showed different behavior to preheating, ethylene glycol solvation, and chemical treatments. Whereas tannic acid showed two prominent exothermic peaks at 390° and 510°C, all hydroxy-Al-tannate-mont-morillonite complexes showed a broad exotherm at about 400°–450°C. Some complexes showed, in addition, a small inflection between 350° and 420°C. The complexes also showed distinct differences in cation-exchange capacity, carbon content, extractable Al, titratable acidity, and mode of aggregation after drying.

Photocatalytic activities of microcrystalline titania incorporated in sheet silicates of clay

Photochemical and photocatalytic properties of microcrystalline TiO{sub 2} incorporated in the interlayer space of montmorillonite were investigated in reference to those of TiO{sub 2} powder particles which were prepared by agglomeration of a titania sol that was used in the preparation of the titania-pillared clay. The pillared TiO{sub 2} microcrystallites having ca. 15-{angstrom} pillar height showed a ca. 0.58-eV blue shift in its absorption and fluorescence spectra compared with those of the TiO{sub 2} particles, exhibiting the quantum size effect. The excited electronic states of the pillared TiO{sub 2} were determined to be 0.36 V more negative than that of the TiO{sub 2} powder particles. Photocatalytic activities of the pillared TiO{sub 2} were greater than those of the TiO{sub 2} powder particles for decomposition of 2-propanol to give acetone and hydrogen and of n-carboxylic acids with up to eight carbons (from acetic acid to caprylic acid) to give the corresponding alkanes and carbon dioxide, though the pillared TiO{sub 2} exhibited lower activities for decomposition of capric acid, having 10 carbons in a molecule.

Hydroxy-aluminosilicate interlayers in montmorillonite: implications for acidic environments

Hydroxy-aluminosilicate (HAS) ions are one of the major forms of soluble aluminium and the precursor of non-crystalline aluminosilicates in acidic (pH<5.5) environments1–6. Acidification in acid-vulnerable areas7,8 would thus promote HAS formation. Over four decades the study of interactions of soluble aluminium species with clay minerals has been focused on the deposition of hydroxy-aluminium in interlayer spaces of expandable layer silicates9–12. Although the synthesis of 'hydroxy-silicoaluminium pillared smectites' as cracking catalysts has been recently attempted13, the nature of the dominant species adsorbed by smectites from the mixture of HAS, hydroxy-aluminium ions and silicic acid remains obscure. Here we provide evidence that HAS ions can be adsorbed in the interlayer spaces of montmorillonite, resulting in an expanded structure, and so the natural occurrence of HAS-interlayered layer silicates merits attention. Furthermore, the transport of HAS ions, their transformation to non-crystalline aluminosilicates and the levels of toxic solution aluminium species in acidic terrestrial and aquatic environments can thus be affected by naturally occurring expandable layer silicates such as montmorillonite.

Reactions of Polynuclear Hydroxyaluminum Cations with Montmorillonite and the Formation of A 28-Å Pillared Complex1

Reactions of Polynuclear Hydroxyaluminum Cations with Montmorillonite and the Formation of A 28-Å Pillared Complex1

Fluorescence properties of the dye-intercalated smectite

The fluorescence properties of the dye Rhodamine 590 and Rhodamine 640 intercalated into montmorillonite were studied. All of the intercalation reactions were accomplished in an ethanol solution which contained the corresponding quality of Rhodamine. The TG-DTA and the X-ray diffraction data showed that the immobilization of Rhodamine depended on the amount of ethanol incorporated in the interlayer space of montmorillonite. The 14.8 Å basal spacing of products indicated a conformation of Rhodamine with the xanthene nucleus and the phenyl group positioned parallel and perpendicular to the silicate layer, respectively. Also, the infrared pleochromism, which supported the proposed orientation of the phenyl group, was observed at 1250 and 712 cm −1. The main fluorescence bands of both products were observed near 600 nm when excited by the 514.5 nm line of an argon ion laser. The results indicated that the mesomeric structure determined the fluorescence behavior, which was little different for the two products owing to the environment of the interlayer. These data are briefly discussed relative to the reaction conditions utilized for the synthesis of products. Also, the results support the idea that the products have a high potential for use as a host for a tunable laser.

Review of the Diffusion of Water and Pyridinein the Interlayer Space of Montmorillonite: Relevance to Kinetics of Catalytic Reactions in Clays

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.

In Vitro Adsorption-Desorption of Papaverine Hydrochloride by Montmorillonite

AbstractIn an attempt to obtain the basic data necessary in research into the possible use of papaverine in sustained action formulas in the form of complexes with Montmorillonite, the “in vitro” adsorption and desorption of the drug as a function of different factor was studied.The study of the interaction and adsorption mechanisms was carried out by adsorption isotherms, X-ray diffraction and I.R. spectroscopy.The adsorption of papaverine by Montmorillonite increases with the rise in pH of the solution, within the pH range studied (2-4) in agreement with the solubility of the compound. According to the isotherms, adsorption increases with the concentration of the solution up to 79.16 mEq/100 g (very close to the exchange capacity of the clay). The data fulfill Langmuir's equation, implying a chemical adsorption mechanism.The results of the X-ray diffraction and I.R. spectroscopy studies confirm the intercalation of the organic cation into the interlayer space of montmorillonite, forming a complex of def...

Factors influencing interactions of organophosphorus pesticides with montmorillonite

A summary is made of the results obtained from the study of the adsorption and interaction mechanisms of a series of organophosphorus pesticides (phosphates, phosphorothiolates, phosphorothionates and phosphorothiolothionates) with montmorillonite, with the aim of establishing relationships between the chemical structure of these compounds and the adsorption and interaction mechanisms with this clay. Many of the organophosphorus pesticides studied are adsorbed into the interlayer space of montmorillonite. The intercalation causes different degrees of expansion (different types of complexes) principally as a function of the chemical structure of the organic compound. The presence in the organic molecules of the P0 and PS groups and the size and composition (functional groups present) of the radicals are the two most important factors. Both the nature of interlayer cations and the previous hydration status of montmorillonite influence adsorption. In some cases the polarizing power of the interlayer cation is a conditioning factor of the degree of interlayer expansion, whereas in others the cation charge is responsible for this. Results of infrared spectroscopy show that interaction is of the dipole ion type and that it depends on the presence of the P0 or PS group in the molecule and also on the functional groups present in the side chains. These factors, together with the situation of these latter groups in the side chains, condition the arrangement adopted by the molecules of a pesticide in the interlayer space.

Analysis of finely divided metal particles formed in montmorillonite by scanning electron microscopy

AbstractFinely divided metal particles, formed in the interlayer space of montmorillonite, have been identified by a x‐ray microprobe technique and their dimensions measured by scanning electron microscopy. The dimensions of Ni0 and Cu0 obtained on reduction of the respective metal ions by H2 have been shown to be ∼ 100 Å.

IR and X-ray diffraction study of chlorpheniramine maleate–montmorillonite interaction

As a contribution to studies on the adsorption of drugs by clay minerals aimed at achieving sustained action in the oral administration of antihistamines, the adsorption of chlorpheniramine maleate by sodium montmorillonite was studied by X-ray diffraction and IR spectroscopy. The results indicated that the chlorphenirammonium ion penetrated into the interlayer space of montmorillonite, producing an increase in the basal spacing, d001, of the silicate. This increase was influenced, as was the amount adsorbed, by the pH and the concentration of the chlorpheniramine maleate solution. At pH 7.0, the amount adsorbed was close to the exchange capacity, and the complex formed had a basal spacing of 17.14 Å (Δ = 7.54 Å). The only mechanism responsible for the interaction was cation exchange. The complex at 17.14 Å must be a monolayer with the benzene rings positioned perpendicular to the surface of the oxygen atoms.

Adsorption of chlorpheniramine maleate by montmorillonite

In an attempt to achieve sustained action in the oral administration of antihistamines, the interaction between montmorillonite and chlorpheniramine maleate (3-chlorphenyl-N, N-dimethyl-3-pyrid-2'-ylpropylamine) has been studied by adsorption isotherms, X-ray diffraction and I.R. spectroscopy. From the adsorption studies, it may be deduced that: (1) the amount of chlorpheniramine adsorbed by sodium montmorillonite increases with the increase in the pH of the solution; (2) the reaction is rapid and there is no additional adsorption of the compound after 15 min of treatment; and (3) the maximum amount adsorbed, according to the adsorption isotherms (pH = 7 and 30 min of treatment), is very close to the cation exchange capacity of montmorillonite (80 mEq/100 g). The results from X-ray diffraction and I.R. spectroscopy show that the organic molecules are adsorbed into interlayer space of montmorillonite, and that the cation exchange is the mechanism responsible for these interactions.

The Interaction Between Roundup (Glyphosate) and Montmorillonite. Part I. Infrared Study of the Sorption of Glyphosate by Montmorillonite

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.

Mechanism of Adsorption of Clindamycin and Tetracycline by Montmorillonite

IR and X-ray analyses of the interaction of clindamycin with montmorillonite indicate that clindamycin is adsorbed by a cation-exchange mechanism under pH conditions favoring the cationic form of the drug and by physical adsorption when the unionized drug is present. This physical adsorption is relatively weak since the drug is readily desorbed by alkaline washing. Tetracycline is adsorbed by cation exchangeat low pH values where the +00 species predominates. Complexation with divalent interlayer cations contributes significantly to adsorption at higher pH values where the +−0 and +−−− species exist. In a strongly alkaline solution, the 0-- species was not adsorbed in the interlayer space of montmorillonite but rather produced an external calcium-tetracycline complex. This study illustrates the utility of X-ray and IR analyses in elucidating the mechanisms responsible for clay-drug interactions.

HYDROXY ALUMINUM SULFATE–MONTMORILLONITE COMPLEX

The nature of the complex that had been formed by precipitating aluminum hydroxide between interlayer spaces of montmorillonite in the presence of anions Cl and SO4 was examined by chemical, X-ray, thermal, and infrared absorption methods. Results indicated that the complex was a hydroxy aluminum sulfate–montmorillonite with the structural formula: Al0.02(H2O)3[Al(OH)2.53(SO4)0.18] + silicate layer of montmorillonite [O10(OH)2 basis]. The atomic ratio, Al:OH:SO4, of the interlayer material was 1:2.53:0.18, which was similar to the ratio 1:2.5:0.25 of "basaluminite." X-ray data showed that the complex had spacings of 19.7, 21.9, and 24.4 A, under an extremely dry condition, moist condition, and on solvation with glycerol, respectively. During the heat treatments between 100 and 200 C, the d001 spacing was sharply reduced to 16 A and the newly developed phase persisted over a wide range of temperature from 200 to 600 C. This phase was considered as an interstratified structure consisting of a 14.3-A unit (chloritelike structure) and a 17.7-A unit (dehydrated basaluminite + silicate layer of montmorillonite). Although the d001 spacing observed for the unheated material was larger than that expected for the amount of aluminum precipitated in the montmorillonite, it was interpreted in terms of voluminous Al13O40 polyhedra that were described previously as basic structural units of a basic aluminum sulfate.

Chloritization of Montmorillonite by Its Coprecipitation with Magnesium Hydroxide

AbstractA magnesium hydroxide-montmorillonite complex prepared at an OH/Mg molar ratio of 2 (16 meq Mg/g clay) and immediately cleaned of any free Mg(OH)2 behaves like magnesium-chlorite and shows no change during 3 months ageing. Magnesium hydroxide completely precipitates within the interlayer space of montmorillonite. X-ray diffraction analysis, thermal (DTA and TGA) studies, i.r. absorption analysis, polarographic reduction behaviour, and cation exchange capacity measurements confirm the transformation of montmorillonite to a chlorite-like structure. Further ageing of the complex results in the release of brucite from the interlayer space and expansion of the complex on glycerol treatment. X-ray analysis of the 6 months aged sample shows the presence of free brucite but not montmorillonite. A small but significant increase in CEC of the complex is observed on ageing. When the Mg(OH)2-montmorillonite complex is allowed to age in the presence of free Mg(OH)2 (external to montmorillonite unit layers) in a dry state, a “seeding” effect takes place and the “fixed” Mg(OH)2 starts coming out from the interlayer space after 10 days.

Reactions of Surfactants with Montmorillonite: Adsorption Mechanisms

AbstractFour clays were treated with each of eight surfactants at three treatment rates. Volclay and the clay fraction from two montmorillonitic soils were treated with 100, 50, and 10 mmol /100 g.; and kaolinite was treated with 10, 5, and 1 mmol /100g.Adsorption was measured quantitatively by the thermogravimetric method. Adsorption mechanisms were investigated by X‐ray diffraction and differential thermal analysis.The surfactants included three anionic, three cationic, and two nonionic compounds. The anionics were not adsorbed in appreciable quantities and anion exchange of kaolinite appeared to be equal to or somewhat greater than that of montmorillonite. Anionics had no effect on the d‐spacing of montmorillonite and did not interfere with hydration of clay surfaces.Cationics were strongly adsorbed by the clay surfaces through ionic bonding in amounts equal to or even greater than the cation‐exchange capacities of the clays. The excess material was probably held by van der Waals forces between the alkyl radicals which increased with chain length. Their presence on clays significantly reduced hydration and water content to the extent of making the clay surfaces completely hydrophobic at the high treatment rates.Nonionics were adsorbed by hydrogen bonding of polar‐active groups to oxygen‐rich clay surfaces. Their sorption energies were somewhat greater than that of water, and they displaced water when adsorbed. Both cationic and nonionic compounds were held in the interlayer spaces of montmorillonite and tended to form double layers if sufficient material was present.

Infrared Study of the Adsorption of Benzoic Acid and Nitrobenzene in Montmorillonite

AbstractNitrobenzene and benzoic acid are coordinated through water molecules to the more highly polarizing exchangeable cations in the interlayer space of montmorillonite, but are directly coordinated to NH4+ and possibly also K+: On dehydration of the adsorption complexes the nitrobenzene and benzoic acid become directly coordinated to all of the exchangeable cations investigated. Benzoate ion was also formed in amounts which were dependent on the exchangeable cations.