Vermiculite

About: Vermiculite is a research topic. Over the lifetime, 2320 publications have been published within this topic receiving 37142 citations.

Ammonium fixation by soil and pure clay minerals

Abstract: Fixation of the ammonium ion (NH4 +) by clay minerals is an alternate way of building the nitrogen (N) pool in soil to optimize N crop recovery and minimize losses. Clay minerals (illite, montmorillonite, and vermiculite) and an illitic Portnoeuf soil were used to compare NH4 + fixation abilities. Total N determination and X‐ray diffraction analysis were performed on each of the minerals and the Portnoeuf soil controls, and NH4 + saturated batches were subsequently desorbed by potassium chloride (KCl) after 4096 hours. Total N was determined for each employing either Kjeldahl digestion only, or pretreating with hydrofluoric‐hydrochloric acid (HF‐HCl) before the Kjeldahl digestion. The total N for the soil was 38% more after pretreatment with HF‐HCl. The total N determined after pretreatment with HF‐HCl for the NH4 + saturated and subsequently KCl desorbed minerals was found to be highest in vermiculite. The cation exchange acapacity (CEC) of each of the minerals was determined, and highest CEC wa...

Luminescent EuIII Complexes Immobilized on a Vermiculite Clay Surface

Abstract: Vermiculite clays were leached with nitric acid and functionalized with (3-chloropropyl)trimethoxysilane. The resulting materials were modified with the methylimidazolium (MID) group to yield cationic surfaces. These materials were characterized by infrared spectroscopy, elemental analyses, and specific surface area. Tetrakis(β-diketonate)europate(III) complexes, [EuL4]– [L = dibenzoylmethane (DBM) and thenoyltrifluoroacetone (TTA)], were immobilized on the vermiculite surface containing the imidazolium cation to yield hybrid surfaces named Vx-MID-EuL4 (x = 0, 1, and 2), in which x represents the acid nitric concentration in mol L–1 that is used in the leaching process. The highest luminescence intensities of the intraconfigurational-4f 5D07FJ transitions (for which J = 0, 1, 2, 3, and 4) arising from [EuL4]– complexes were presented by the hybrid materials containing the amount of imidazolium cation, which depend on the leaching process. The excitation and emission spectra suggested an efficient intramolecular energy-transfer process from ligand-to-Eu3+ ion in the supported materials. The photoluminescent properties of the hybrid materials were investigated based on the emission quantum efficiency (η), experimental intensity parameters Ω2 and Ω4, and Einstein's emission coefficient (A0J). The values of these parameters for the V2-MID-EuL4 surface are close to those assigned to the [EuL4]– isolated complexes, which indicates that hybrid vermiculite materials are promising red phosphors.

Specific Surface Determination by Duo-Interlayer and Mono-Interlayer Glycerol Sorption for Vermiculite and Montmorillonite Analysis1

Abstract: In a new method for specific surface determination, montmorillonite is made to sorb exactly two interlayers of glycerol (a true monolayer on each planar surface) at 35° C. in a vacuum of < 1 mm. of Hg. Vermiculite sorbs only one interlayer under these conditions. Both montmorillonite and vermiculite sorb only a mono-interlayer of glycerol at 110° C. in a previous method. The two analytical methods thus give the amount of glycerol corresponding to the second interlayer in montmorillonite, and this makes possible quantitative analytical determination of montmorillonite and of vermiculite. To illustrate, Wyoming montmorillonite sorbs 21.1% glycerol at 110° C., and 41.6% at 35° C. in vacuum, which gives an analysis of 98% montmorillonite, whereas Colorado vermiculite sorbs the same amount of glycerol under both these conditions, equivalent to only a monointerlayer. The presence of fine amorphous material in montmorillonitic fine clays is revealed by a higher specific surface than obtained with 100% montmorillonite. Dissolution of the allophane from Black Cotton soil (India) resulted in a specific surface analysis of 94% montmorillonite (5 to 10% kaolinite is present). Ladybrook fine clay fraction (Queensland, Australia) showed 90% montmorillonite and 10% of mono-interlayer expanding mineral.

Effect of Iron Removal and Dispersion Methods on Clay Mineral Identification by X-Ray Diffraction1

Abstract: The clay minerals identified in soil samples were found to be dependent on the pretreatment of samples for iron removal and dispersion. Treatments affected the characterization for chlorite, montmorillonite-type minerals, vermiculite, and intergrade components. Increases in the degree of expansion upon solvation and in degree of collapse upon K-saturation and heating were related to the severity of treatments used for dispersion. Iron removal treatments also increased the ease of expansion and collapse to 2:1 lattice clays. It was concluded that certain pretreatments tended to remove interlayered materials which were present in these samples. The degree to which clay mineral interpretation was affected by methods of pretreatment was not the same for all soils. Samples of the Astoria soil exhibited the greatest differences in diffraction patterns as a result of dispersion and Fe removal treatments while the Aiken was the least affected. The Willamette was found to be intermediate. The evidence suggested that the Astoria samples contained interlayer materials (intergrade components) which were poorly crystallized and thus more labile and subject to removal. On the other hand, the interlayer material in the Aiken seemed to be better crystallized and more toward the chlorite end of the spectrum. It has sometimes been assumed that the methods which permit the identification of the largest number of components with “clean-sharp” peaks are the ones which should be used in sample preparation. It is suggested that the objective should be to obtain methods which permit the identification and reflect the properties of clay minerals as they existed in situ.

Production of vermiculite products and suspension for use therein

Abstract: A process for producing solid vermiculite products which are stable in water which comprises incorporating a urea-formaldehyde or melamine-formaldehyde resin in an aqueous suspension of vermiculite lamellae, shaping the suspension and removing water from the suspension, and curing the shaped composition by heating during and/or after removal of water from the suspension. The invention includes an aqueous suspension of vermiculite lamellae having a resin incorporated therein and a dry-powder mixture of vermiculite lamellae and a resin.