Showing papers on "Vermiculite published in 1996"

Morphological and Chemical Features of Bioweathered Granitic Biotite Induced by Lichen Activity

Abstract: To study the physico-chemical activity of lichens on micaceous components of granitic rocks, samples covered by thalli of Parmelia conspersa (Ehrht) Ach. and Aspicilia intermutans (Nyl.) Arn. were collected and examined with Scanning Electron Microscopy (SEM) equipped with a Back Scattered Electron (BSE) detector and an Energy Dispersive Spectroscopy (EDS) microanalytical system. The bio-physical activity of both lichen species leads to a deep alteration of biotite, which results in detachment, separation and exfoliation of biotite plates. Chemically, the bioweathering process of biotite in the lichenmineral contact zone involves considerable depletion of potassium (K) from interlayer positions in biotite and removal of several elements, corresponding to a 9.7% loss in matter. The sequence of the loss of elements is: K+ » Fetot > Ti4+ ≅ Mg2+. There are also some gains in the order: Ca2+ > Na+ » Al3+ > Si4+ attributed to dissolution of co-existing Ca and Na rich minerals. Geochemical mass balance results suggest the transformation of K-rich biotite to scarcely altered biotite interstratified with a biotite-vermiculite intermediate phase in the lichen bioweathered contact zones.

Weathering of chlorite in a quartz-chlorite schist: I. Mineralogical and chemical changes

Abstract: The weathering of chlorite, one of the major minerals of the host rock in the uranium ore deposit at Koongarra, Australia, was examined by X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), electron microprobe analysis, and transmission electron microscopy (TEM). The conversion sequence of chlorite weathering is: (1) chlorite; (2) chlorite/vermiculite intergrade (showing XRD responses to various treatments intermediate between those of chlorite and vermiculite); (3) interstratified chlorite and vermiculite; (4) vermiculite; and (5) kaolinite. This sequence may be more simply expressed as chlorite ⤒ vermiculite ⤒ kaolinite. The weathering finally changed chlorite into sub-micrometer to micrometer sized Fe minerals and kaolinite. The transformation of chlorite to vermiculite is chemically characterized by an Fe and Mg loss with a slight decrease in the Al/Si ratio. Mg continues to be released throughout the weathering. Fe minerals formed through chlorite weathering are located between chlorite and vermiculite domains (a few u,m in size) at first, and then accumulated between grain boundaries, occasionally forming veins. The distribution of Fe minerals is suggestive of preferential pathways of water movement. The time-dependent nature of mineral alteration demonstrated in the present study must be taken into account for the quantitative estimation of radionuclide migration.

Color Removal from Dye Wastewater Using Vermiculite

Abstract: The purpose of this laboratory study was to investigate the effectiveness of vermiculite extract solutions (VES) as a coagulant and of vermiculite as an adsorbent for removal of color from dye wastewater. In coagulation experiments, it was found that VES could be applied to the treatment of dye wastewater with its contents of various cations (e.g. Mg, Fe, Al, Ca, Si etc.) useful for coagulation. Coagulation with VES produced less sludge at a lower coagulant dosage in comparison with to conventional inorganic coagulants. For evaluation of adsorption characteristics of vermiculite on basic dye wastewater, adsorption parameters for Langmuir and Freundlich isotherms were determined. The adsorption of the basic blue dye on vermiculite was found to conform with both isotherms. The adsorption capacity of vermiculite was found to increase with the decreasing particle size and with the increase of temperature and of intensity of agitation. The results indicate that vermiculite is an excellent adsorbent for basic b...

Characterization of soil clay minerals; decomposition of X-ray diffraction diagrams and high-resolution electron microscopy

Abstract: Fine clays (<01 μm) extracted from an acid soil developed in a granite saprolite from the Massif Central, France, were characterized by X-ray diffraction (XRD) using a curve decomposition program, and high-resolution transmission electron microscopy (HRTEM) associated with a method of impregnation of moist samples Direct measurement of d-spacings were performed on HRTEM photographs Decomposition of XRD patterns indicated 5 to 6 different clay phases including chlorite (and/or hydroxy-interlayered vermiculite), vermiculite/smectite, illite/vermiculite and illite/smectite mixed layers Expandable phases with decreasing layer charge (vermiculite, high- and low-charge smectite) were shown in the clay assemblage When performed on K-saturated samples subjected to wetting and drying cycles, HRTEM observations were consistent with the XRD results The major clay mineral phases identified by the decomposition of XRD patterns were also found by direct measurement of d-spacings on HRTEM images Vermiculite and high-charge smectite appeared to be impregnated with preservation of their initial hydration state, whereas low-charge smectite interlayers were penetrated by the resin molecules during the impregnation procedure It was concluded that the decomposition of XRD patterns gave a realistic analysis of the clay phases present in a complex soil clay sample, as well as the direct measurement of a limited number (50) of clay crystals on HRTEM images

Direct identification of biotite/vermiculite layers in hydrobiotite using high-resolution TEM

Abstract: The microstructure of hydrobiotite, interstratified biotite/vermiculite, was examined to demonstrate an atomic scale investigation of weathering of minerals by high-resolution transmission electron microscopy (HRTEM). Vermiculite basal spacing was collapsed to about 0.95 nm, compared to the unchanged biotite 1.0 nm spacing, by dehydration probably during the ion-milling sample preparation. Atom-resolving structure images with 0.2 nm point resolution show a distinct difference between K-containing and K-depleted interlayers, corresponding to biotite and vermiculite respectively. Thus, the difference in image enables us to identify vermiculite layer positions in hydrobiotite unambiguously. Although the vermiculite layers are randomly formed in the original biotite, there is a tendency to form 1:1 regular biotite/vermiculite interstratification locally. In some interlayers the contrast of potassium columns changed gradually, which suggests that biotite is directly transformed to vermiculite in the weathering process. These observations demonstrate atom-resolving HRTEM is a useful method for structure analyses of such water containing secondary minerals as vermiculite in spite of spacing changes caused during sample preparation or observation in TEM.

The dust content, dust generation, ammonia production, and absorption properties of three different rodent bedding types

Abstract: Vermiculite, pine shavings and unbleached eucalyptus pulp contact bedding were compared for dust content, dust production (as a result of animal activity), moisture absorption properties and ammonia production. The percentage of dust particles <300 microm found in pine shavings and vermiculite was 18 and 8 times greater respectively than was found in eucalyptus pulp. The lowest ammonia levels (<1-1 ppm), measured on day 7, were obtained using eucalyptus pulp. Although the ammonia levels obtained for vermiculite compared very well with those of pulp, high levels of dust, up to 5 times more than pulp, were experienced with vermiculite. Pine shavings were associated with the highest ammonia concentration (1-3 ppm), but produced approximately 50% less dust than vermiculite. The water absorption properties obtained for pulp were between 35% and 76% higher than those obtained for vermiculite and pine shavings respectively.

Filter material of ceramic oxide fibers and vermiculite particles

Abstract: Filter material comprising fabric of ceramic oxide fibers and vermiculite particulate is disclosed. The presence of the vermiculite provides an improvement in the flexural endurance of the fabric.

Transition Metals in Llano Vermiculite Samples: an EPR Study

Abstract: Continuous wave and pulsed electron paramagnetic resonance spectroscopies combined with thermal and chemical methods were used to identify and characterize V(IV), Fe(III), Mn(II) and Cr(III) in a multimineral system that consists of vermiculite and impurities of carbonates. All of these transition metals were structure-bound in mineral phases. The V(IV) was located in octahedral layers of the vermiculite and became oxidized to V(V) during the transformation of the host mineral to enstatite at about 800 °C. The Fe(III) was associated with the vermiculite as well as the carbonate impurities. The Fe(III) identified in the vermiculite was transferred into the enstatite structure during the thermal conversion. An indirect proof of Fe(III) and Cr(III) in the impurities was found in the heated samples in which these cations occurred in Ca and/or Mg oxides that were formed by transformation of the carbonates. The Mn(II) in the untreated samples was associated with the impurities and was also detected in oxides formed from the samples heated at 600 °C.

Acid activated montmorillonite and vermiculite clays as dehydration and cracking catalysts

Abstract: Treatment of montmorillonite and vermiculite with hydrochloric acid results in an overall increase in acidity and acidic sites. IR and DSC studies of base adsorbed catalysts have revealed the heterogeneity of surface acidity on the activated catalysts. Clay catalysts have been found to dehydrate 1-butanol to 1-butene, which directly isomerizes tocis- andtrans-2-butenes, confirming the presence of Lewis and Bronsted acid sites. Cumene cracking studies using the clay catalyst also confirm the presence of Bronsted acid sites. The temperature and concentration of acid have been found to have a significant influence on the catalytic activity.

Fontes potenciais de potássio em alguns solos do Rio Grande do Sul

Abstract: This study investigates the mineralogy ofA horizons of three soils of Rio Grande do Sul State, Brazil: a Vertisol, an Ultisol and an Oxisol, to identify potential sources of potassium for plants in sand, silt and clay fractions. The differences in the distribution ofpotassium sources among soils are related to the dominant minerals. The highest potassium content is found in the vertisol, due to the presence of feldspars, mica, mica-vermiculite, vermiculite and smectite, followed by the ultisol, with mica-vermiculite and vermiculite with hydroxi-Al interlayers. The lowest potassium contents, found in the oxisol, are related to orthoclase feldspars in the sand and silt fractions: the potassium source in the clay fraction of this soil is probably associated to the smectite with hydroxi-Al interlayers. In the vertisol and ultisol, all granulometric fractions are potential sources of potassium, while in the oxisol, 76% of total potassium is located in the clay fraction. In all soils, the amount of non-exchangeable potassium is low when compared to the total content in each fraction, and is concentrated in the clay fraction. The increment in non-exchangeable potassium and total potassium in the sequence oxisol - ultisol - vertisol, is due to the decrease in kaolinite and to an increase in micaceous and expansive clay minerals and feldspars.

Evolution of benzylammonium-vermiculite and ornithine-vermiculite intercalates

Abstract: This report consists of a study of l-ornithine hydrochloride-vermiculite and of benzylammon-ium hydrochloride-vermiculite complex. The evolution of these organo-vermiculite structures upon heating is studied by X-ray diffraction (XRD) as well as infrared spectroscopy.

Elemental distribution and mineralogy of arid zone soils of Punjab

Abstract: In soils of dune complex, the weighted mean values of different elements were in the order: Ca > Fe > Na > K > Mg > Zn > Mo > Cu. Compared to the average values for the soils, these soils were rich in alkali and alkaline earth elements but poor in micronutrient elements. The minerals assemelage comprised feldspar, muscovite, biotite, chlorite, kaolinite and calcite in the coarse fractions. Mica, kaolinite, chlorite and vermiculite were dominant in the soil clays. The positive correlations of all elements with silt and clay contents and negative correlations with sand content indicated that the host minerals of these elements were in finer fractions. Anatase was positively correlated with Cu, Zn, Fe, Mg and Ca. Silt size feldspar had positive correlation with Cu, Zn and Mg, but other size had negative correlation with Zn, Fe, Mg and Mn.

A methodological approach to the application of a vermiculite modified carbon paste electrode in interaction studies: Influence of some pesticides on the uptake of Cu(II) from a solution to the solid phase.

Abstract: A new methodological approach, for studying metal ion binding interactions with a clay mineral is presented. A carbon paste electrode (CPE) modified with vermiculite clay mineral was used as a model for a soil-like solid phase and Cu(II) ions were chosen as the test ions. The application of this model is demonstrated and explained by investigating the influence of seven pesticides (bromofenoxim, fenamiphos, phenmedipham, atrazine and its three natural degradation products) on the uptake of Cu(II) ions from a solution to the vermiculite, included in a CPE. Different conditions (pH, concentration, exposure time etc.) were considered and the amount of bound copper, accumulated when no potential was applied, was then determined by stripping voltammetry.

The nature of smectites and associated interstratified minerals in soils of the Gharb plain of Morocco

Abstract: Summary The mineralogies of ‘Tirs’ (Typic Pelloxererts), and ‘Debs’ (Typic Haploxerolls and Typic Xerochrepts) soils of the Gharb plain in north-western Morocco are investigated, with special attention given to the determination of the nature of the smectitic phase using the lithium test (Li test) and the alkylammonium method. The sand and silt mineralogy of Tirs soils is dominated by quartz with small amounts of feldspars and kaolinite. The sand and silt fractions of Dehs soils also contain significant amounts of mica, chlorite, and interstratified phyllosilicates. The clay minerals of Tirs soils are predominantly a high-charge smectite. The estimated interlayer charge for this phase is 0.61 mol(c)/O10(OH)2 and the fraction of tetrahedral charge varies from 38 to 44%. Although the percentage tetrahedral charge is less than 50%, the smectitic phase behaves as beidellite with the Li test. Dehs clays are more heterogeneous, consisting of smectite, vermiculite, illite, kaolinite, chlorite, and interstratified illite/smectite and illite/vermiculite. The Li test and the alkylammonium method demonstrate that a high-charge smectite or vermiculite is interstratified with illite. A low-charge montmorillonite is also present both in Tirs and in Dehs soils. The high-charge beidellitic phase is believed to be a transformation product of mica, whilst the low charge montmorillonite is thought to be inherited from the parent material.

Base material for vegetation on earthwork structure such as side slope, and creation of vegetation bed for earthwork structure such as side slope

Abstract: PURPOSE: To easily create a sufficiently effective vegetation bed on the outside of an earthwork structure such as a side slope by a method wherein hollows available for housing soil therein are formed on one side of a base body formed of coconut fibers or peat moss CONSTITUTION: A base material body 1 is formed of coconut fibers or peat moss A plurality of hollows 3 are formed on one side 1a of the base material body 1 Large hollows 4 out of the hollows 3 are filled with a mixture comprising of soil 6 composed of natural soil such as decomposed granite soil, peat moss, vermiculite, etc, and artificial soil, a fertilizer for vegetation and plant seeds, while small hollows 5 are filled with a slow effective fertilizer Furthermore, the base material body 1 is wrapped with a net-like bag 7 Thereby, a sufficiently effective vegetation bed can be easily created on the outside of an earthwork structure such as a side slope

Alteration of Mica and Chlorite in Paddy Soils Derived From Triassic and Jurassic Sediments.

Abstract: The alteration of mica, chlorite and their related mineral in parent rocks from two terrains being the Middle Triassic to the Middle Jurassic was discussed in two paddy fields of Gray Lowland soils located in Fukui Prefecture. Mica hardly altered to other mineral, but lost iron from its layer lattice and its crystallinity degraded a little in both two soils. Mica-vermiculite interstratified mineral in the Mino Terrain altered to vermiculite. Iron-rich chlorite in the Tanba Terrain changes partially to chlorite-vermiculite intergrade with the decrease of iron from its layer lattice. The alteration of these minerals was due to the decrease of iron content, the decrease of layer charge and the degradation of crystal structure, through the pedogenesis under the seasonally reductive condition.

Improvement of cesium leaching resistance of solidified borate wastes with copper-ferrocyanide-vermiculite adsorbent

Abstract: Removal of cesium from deionized water, sea water, and lime water with copper ferrocyanide (CFC) and porous media including silica gel, bentonite, vermiculite, and zeolite were investigated; CFC and vermiculite were incorporated to prepare a compound adsorbent which was used to improve the Cs-leaching resistance of solidified borate wastes. It was shown that the Cs-removal efficiency by CFC is largely affected by pHs of the solutions, good cesium removal occurs in pHs ranged from 3 to 12 and the best from 7 to 10; the effect of Cs concentration is significantly only from lime water for Cs > 10{sup {minus}6} M at high pH and is insignificant from other solutions. Vermiculite and zeolite were shown to have better removal efficiency than silica gel and bentonite, and vermiculite was chosen to incorporate with CFC to make compound adsorbents because of its good compatibility with CFC. Compound adsorbents with different CFC contents were used as additives in the solidification of borate radwaste for improving the cesium leaching resistance of waste forms. Experimental results showed that the measured, cesium leaching index following ANSI/ANS 16.1, was increased from 7.96 to 9.76 by adding 0.25% of a compound adsorbent containing 20% CFC and 80% vermiculite,more » which indicated that the CFC-vermiculite compound adsorbent is very useful for improving cesium leaching resistance of the solidified borate radwastes.« less

Self-lubricating composition containing cellulose, resin, vermiculite, nut shells, fluor spar and oil

Abstract: Self-lubricating material comprises (a) 4.0-9.0 wt.% of a cellulose, (b) 15.0-20.0% of a resin, (c) 20.0-25.0% of vermiculite of defined particle size, (d) 12.0-20.0% of fruit shells, (e) 11.0-14.0% of fluor spar, and (f) 20.0-26.0% of an oil.

Chlorites and chloritic mixed-layer minerals in profiles on ultrabasic angiquinho (brazil) rocks from m oyango (ivory coast) and

Abstract: A B ST RAC T : Different types of chlorite and related mixed-layer minerals have been found in profiles developed on ultrabasic rocks of Ivory Coast and Brazil. Normal chlorites, with low K and Ni contents, are of hydrothermal origin and are situated at the bottom of the alteration profile. At the top of the profile the mixed-layer minerals are Ni-chlorite/vermiculite, which formed under weathering conditions, or K-chlorite/vermiculite, resulting from the alteration of mica. The Ni-content of the chloritehermiculite can reach 10% NiO.

Demonstration of the Influence of Mg Vermiculite on the Activity of Cellulosic Agents and Diazotrophs During Composting of Lignocellulosic Residues

Abstract: Adsorption and desorption properties, of a magnesian vermiculite (VMg), have been used to follow the dynamic of the NH4 + ion ,which has been produced during the ‘cellulotytic-diazotroph’ association appeared during the aerobic fermentation of a mixture of wheat straw and poplar sawdust.This fermentation has been regularly followed for three months in a mini digestor, and temperature, ventilation, pH, humidity, and C/N ratio of macro-elements were controlled. The same is done for the associative activity of cellulolytics and diazotrophes (NUNTAGIJ, et al., 1989). However, if fermentation is not carried out under optimal conditions, there is a loss of ammoniacal nitrogen, and that often occurs during large scale composting of organic residues (MARTIN, 1991). Clay properties can be used to control this loss. Four types of vermiculites are chosen to do so: a natural vermiculite (VMg), an NH4 + saturated vermiculite (NH4 +), a calcium and ammonium-saturated vermiculite, only in exchangeable position (VCaNH4 +) and a vermiculite having exchangeable oligoelements (VMgCaCuCoMnZn).

A kinetic study of dissolution and alteration of vermiculite at room temperature

Abstract: (1996). A kinetic study of dissolution and alteration of vermiculite at room temperature. GFF: Vol. 118, No. sup004, pp. 53-53.

Process for preparing silicon, aluminium and magnesium nitrides and oxynitrides with a fibrous morphology based on vermiculite

Abstract: Process for preparing silicon, aluminium and magnesium nitrides and oxynitrides with a fibrous morphology based on vermiculite. The subject-matter of the invention is a process for the preparation of a ceramic raw material. In this process the organic molecule of acrylonitrile is intercalated with a phyllosilicate (vermiculite) into which n-butylammonium chloride has previously been intercalated. The intercalated monomer can polymerize between the layers of the phyllosilicate in order to produce a mineral-butyl ammonia polyacrylonitrile phyllosilicate complex. Once the polymer has entered the interlaminar space this precursor is subjected to carbothermic reduction in a flow of nitrogen, producing a ceramic raw material containing silicon, aluminium and magnesium nitrides and oxynitrides (B-sialon, B-silicon nitride, and silicon and magnesium nitride) having a fibrous morphology. The products obtained by the method according to the invention have applications as starting materials for the synthesis of advanced ceramic materials with high thermal and mechanical performance.