Showing papers on "Vermiculite published in 2006"

Moisture Retention and Cation Exchange Capacity of Sandy Soil as Influenced by Soil Additives

Abstract: Specific problems in the management of sandy soils include their excessive permeability and were low water and nutrient holding capacities. Hence, a laboratory and pot experiment was carried out to study the effect of soil additives on water and nutrient retention capacity of a sandy soil. The experiment consisted of seven treatments viz., control (Sandy soil alone), application of FYM, bentonite, vermiculite, tank silt, termite mound all applied @ 1 % (or) 20 t ha -1 and humic acid @ 20 kg ha -1 . The results of the laboratory study revealed that application of vermiculite retained more amount of moisture followed by application of bentonite compared to control. The results of the pot experiment indicated that the cation exchange capacity of sandy soil was remarkably increased by the application of vermiculite @ 1 % (or) 20 t ha -1 followed by the application of humic acid @ 20 kg ha -1 .

Effect of acid treatment and alkali treatment on nanopore properties of selected minerals

Abstract: Bentonite, biotite, illite, kaolin, muscovite, vermiculite and zeolite were acidified or alkalized with HCl orNaOH of concentrations 0.0, 0.1, 1.0 and 5.0 mole dm−3 at room temperature for 2 weeks and converted into Ca homoionic forms. Low-temperature nitrogen and room-temperature water-vapor adsorption-desorption isotherms were used to characterize the mineral pores of radii between 1 and 30 nm. Nanopore volumes, size distributions, average radii and fractal dimensions were calculated. Values calculated from the nitrogen isotherms differed from those derived from water-vapor data. With an increase of the acid-treatment concentration, the pore volumes measured using both adsorption techniques increased markedly for all minerals. The pore radii measured from nitrogen isotherms appeared to decrease for all minerals except zeolite, while the pore radius calculated from water-vapor data increased in most cases. The fractal dimension measured from water vapor isotherms decreased in all cases indicating smoothing of the mineral surfaces and decrease in pore complexity. No well defined trends in any of the pore parameters listed above were noted under alkaline treatment. In the reaction of each mineral with acid and alkali treatments, the individual character of the mineral and the presence of impurities seems important.

Non-asbestos static sealing materials and products thereof

Abstract: The invention provides a packing material containing no asbestos and its preparing process, wherein the material is prepared from binders, mica, vermiculite, graphite, organic fiber and inorganic fiber, silicon dioxide, porcelain clay, barium sulfate, anti-aging agent, preservative agent and vulcanizing auxiliary agent through calendaring formation

Chemic exothermic material and exothermic bag

Abstract: A chemical heat-generating material is prepared from iron powder, activated carbon, edible salt, water, vermiculite, diatomite or silicon gel, and high-hydroscopicity resin. A dual-layer heating bag is composed of an internal bag containing said chemical heat-generating material and an external air-tight packing bag.

Influencia de seis sustratos en el crecimiento de Pinus ponderosa producido en contenedores bajo condiciones de invernáculo Influence of six substrates in Pinus ponderosa grown in containers under greenhouse conditions

Abstract: SUMMARY The influence of six substrates on Pinus ponderosa grown was studied in containers under greenhouse conditions. Treatments used were elaborated in a 1:1 proportion with an organic (coco fiber or Sphagnum peat moss) and an inorganic (pumice, vermiculite or perlite) compound. Different morphologic features were measured eight months later. The plants developed on vermiculite showed the best results. The combination of vermiculite with peat moss presented the greater size for all studied variables: stem diameter (4.9 cm), shoot height (25.4 cm), wet and dry weight of the whole plant (20.9 and 5.7 g), dry weight of the aerial and root portion (3.5 and 2.1 g), dry weight of the main root (0.7 g) and dry weigh of secondary roots (1.5 g). Three indexes were also evaluated in order to determine the plant quality. The substrates with vermiculite presented the best behavior for the different indexes.

Interaction between the bacterium Pseudomonas fluorescens and vermiculite : Effects on chemical, mineralogical, and mechanical properties of vermiculite

Abstract: [1] On an expanded and crushed vermiculite, changes in chemical, mineralogical, and rheological properties of the mineral affected by microbial activity were investigated. Determination of the water content, grain size, X-ray diffraction pattern, intercrystalline swelling with glycerol, layer charge, CEC, exchangeable cations, BET surface, and rheology provided the necessary information about the differences between pure vermiculite, vermiculite suspensions containing the nutrient medium, and vermiculite suspensions containing the nutrient medium and the bacterium Pseudomonas fluorescens strain CHA0. The aerobic bacterium Pseudomonas fluorescens causes a decrease in grain size, aggregation of vermiculite grains as evidenced by smaller BET surfaces, and enhanced viscosity of the bacteria containing slurries. Layer charge, intercrystalline swelling, and CEC were not affected by the microbial activity, nor did the bacteria count for the exchange of potassium and magnesium against sodium in the vermiculite. The microbes inhibited this exchange process during the first stage of the experiments; however, increasing run time favors the exchange as well.

'Black' soils in the southern Alps: clay mineral formation and transformation, X-ray amorphous Al phases and Fe forms

Abstract: Many soils in southern Switzerland have a black color, contain a large amount of soil organic matter (SOM) and seem to have some andic properties although they did not develop on volcanic parent material. We investigated three typical 'black' soils to determine the mechanisms of (clay) mineral formation and transformation. We measured total element pools as well as the dithionite-, pyrophosphate- and oxalate-extractable fractions (Fe, Al, Si). The clay fraction (<2 μm) was analyzed using X-ray diffraction and FTIR spectroscopy. Iron speciation in the solid phase was determined by Mossbauer spectroscopy. With increasing weathering conditions, the plagioclase (albite) content decreases, trioctahedral species in the clay fraction such as biotite, chlorite or trioctahedral vermiculite either decompose or transform into a dioctahedral mineral such as dioctahedral vermiculite or hydroxy interlayered smectite (HIS). Typical weathering products were hydroxy interlayered vermiculite (HIV), HIS, interstratified minerals and kaolinite. The oxidation of Fe(II) into Fe(III) was evident and contributes to the transformation of trioctahedral mineral species into dioctahedral ones. In one soil, a large part of the Fe (up to 41%) was found in the form of Fe oxides. In the surface horizon, the poorly crystalline mineral ferrihydrite was dominant, while in the subsoil goethite prevailed. Maghemite (or maghemite/hematite mixture) was, furthermore, found in distinct concentrations down to a depth of ∼50 cm. The formation of this mineral requires high temperatures which means that a forest fire can influence soil mineralogy down to a considerable depth. The specific climatic conditions with periods of strong humidity alternating with periods of winter droughts, sporadic fire events and the relatively large content of poorly crystalline fractions of Fe and Al contributed to the stabilization of SOM.

Chemical and mineralogical transformations in three tropical soils due to permeation with acid mine drainage

Abstract: The chemical and mineralogical compositions of three tropical soils, before and after permeation with 19–24 pore volumes of acid mine drainage (AMD), were assessed using X-ray diffraction and chemical analyses, in order to consider their potential value as clay liners. After permeation the CEC of one soil (Soil K) was reduced, partly due to structural modification of smectite by AMD. Conversely, the other soils (Soils A and H) showed increased CEC values due to structural changes in mixed layer vermiculite minerals, resulting in the formation of vermiculite as a separate phase in the soils. The specific surfaces of the soils were reduced. AMD caused changes in the variable charge properties of the soils due to the composite effects of soil pH and organic matter reduction and the changes in composition of exchangeable ions. Dolomite, gibbsite, diaspore, magnesioferrite and hydroxy apatite were dissolved from the soils. Chlorite was mildly altered but kaolinite was structurally resistant to AMD attack. Jarosites were, however, formed in all the soils. It was concluded that the tropical soils studied could be effective sinks for zinc and nickel from AMD, but that Soils A and H would be the most desirable clay liners for acid mine waste containment due to their low hydraulic conductivity, high sorptive capacity and compatibility with AMD.

Clay Mineralogy of Central Victorian (Creswick) Soils: Clay Mineral Contents as a Possible Tool of Environmental Indicator

Abstract: The clay mineralogy and heavy metal/metalloid (As, Pb and Cu) contents of soils developed on the various rock units in a central highlands environment in Victoria (Creswick, Australia) have been investigated. The clay minerals identified showed an order of abundance as: kaolinite ≫ illite > smectite > mixed-layer (ML) ≈ vermiculite. The soil clay mineralogy did not change systematically with depth (0∼ 10, 10∼ 20 and 20∼ 30 cm) and showed large variations spatially. The high proportion of kaolinite was probably due to the removal of 2:1 phyllosilicates by the formation of 1:1 kaolinite through weathering, which also reduced the cation exchange capacity (CEC) and electrical conductivity (EC, soil: water ratio of 1:5) of soils by aging. Soils were classified as silty loam to loam with a low clay size (≤ 2μ m) fraction. The soils were acidic to moderately acidic with pH ranging from 4.5 to 7.1, averaging 5.7. Concentrations of As, Pb, and Cu (average values 24.3, 16.7 and 11.0 mg/kg, respectively) did not sho...

Effect of interlayer cations on high-temperature phases of vermiculite

Abstract: Static and dynamic heating of vermiculite samples from Santa Olalla, Huelva, Spain, saturated with different cations, i.e. Na+, Cs+, NH4+, Mg2+, Ca2+, Ba2+ and Al3+, have been studied. The characterization of the phases formed during heating has been carried out by X-ray diffraction. The phases formed depend on the cation present in the interlamellar position and the heating process. The phases identified in the vermiculite samples saturated with different cations and heated at different temperatures are the following: enstatite, forsterite, spinel, cordierite, anorthite, pollucite, nepheline, coesite, celsian and others various mixed silicates; also some dehydrated and amorphous phases have been observed. On static heating, at the maximum temperature reached in this work, the phases formed appear mixed with a glassy phase.

Quantification of amphibole content in expanded vermiculite products from Libby, Montana U.S.A. using powder X-ray diffraction

Abstract: Five expanded vermiculite samples known to have originated from the former vermiculite mine near Libby, Montana were analyzed using powder XRD to quantify their amphibole content. An expanded vermiculite with no detectable amphibole based on our XRD methods discussed herein was spiked with 100, 500, 1000, 2500, 5000, 7500, and 10 000 ppm Libby amphiboles to determine the detection limit of XRD and to develop a calibration method. The 110 amphibole peaks were not detectable in the 100 and 500 ppm samples; thus, defi ning the detection limit. The 110 peak areas for the remaining samples were measured and used to form a calibration curve relating peak area to ppm amphibole. Of the fi ve Libby samples, each had detectable levels of amphibole and their amphibole content ranged from 1171 to 9218 ppm. The XRD method provides a bulk measurement of the total amphibole content. To determine the amount of asbestiform amphiboles, morphological considerations obtained by microscopy techniques are required. From the results of a previous polarized light microscopy study, the fi ve expanded vermiculites in this study would contain from 390 to 3073 ppm asbestiform amphiboles and not be subject to regulation on the basis of the 1% rule used by regulatory agencies in the U.S.A.

Serpentine-nontronite-vermiculite mixed-layer clay from the weches formation, claiborne group, middle eocene, northeast texas

Abstract: The Weches Formation of the Claiborne Group (Eocene) in northeast Texas consists of clayey sandstones and mudrocks, both with variable proportions of dark green to brown clay peloids deposited in a marginal to open marine setting on the Gulf Coast margin. The composition of the dark green peloids, from two localities, has been investigated using X-ray diffraction, back-scattered electron microscopy with X-ray analysis, electron energy-loss spectroscopy (EELS), Mossbauer spectroscopy, chemical analysis and Fourier transform infrared spectroscopy. These peloids were previously described on the basis of their color as glauconite (Yancey and Davidoff, 1994); our results, however, show that the dark green indurated pellets are predominantly composed of mixed-layer clays with a high proportion of Fe-rich 7 A serpentine layers coexisting with a mixed-layer phase containing glauconite, nontronite and vermiculite layers, in addition to discrete illite and kaolinte. Analyses by EELS of single particles with a chemical composition consistent with them being the Fe-rich clay indicate that the Fe is >95% ferric, while Mossbauer analyses of the bulk magnetically separated fraction for the same samples indicates a ferric iron content of ~60–70%, despite the variable relative proportions of expandable and 7 A layers. Taking into account that there is a significant amount of 2:1 layers containing ferric Fe, we interpret these data as indicating that the Fe in the 7 A layers has a significant amount of Fe2+ even taking into account the high ferric Fe ratio from the EELS analysis when the coexisting 2:1 layers are considered. Thus, these 1:1 layers are closer to berthierine in composition than to odinite. The vermiculite layers in the Texas clay may indicate partial ‘verdinization’ of expandable 2:1 clay. A possible reaction is smectite → vermiculite → berthierine-like phase. We estimate a temperature of 20°C for the seawater in which the Texas clay formed, the lower end of the range for modern occurrences of odinite.

Experimental investigation of a filter with natural sorbent charge for runoff cleaning from heavy metals and petroleum products

Abstract: An experimental investigation on the removal of heavy metals (HM) and petroleum products (PP) from a solution by natural sorbents zeolite and vermiculite was carried out in a laboratory pilot-scaled test bench. For this purpose a model of a runoff filter which was invented by the authors was used. 25 kg of natural zeolite and 2 kg of vermiculite were used for the filter charge. An experimental solution of 20 l contained 1 g/l of HM Cu, Pb, Zn, Ni and Mn nitrates and 200 ml of PP gasoline and diesel. The solution was poured into the filter through a funnel and passed over natural zeolite and vermiculite media. The first sample was taken through a sample mixer tap immediately after the contact of the experimental solution with the charge media, the second sample was taken after 5 min, then after 10, 20, 30, 60, 120, 240, 360 and 720 min. TOG/TPH analyser was used for measuring concentration of filtrate samples. The highest efficiency of 99,7 % was reached for PP removal from water.

Characterization of Clay Minerals in Brown Forest Soil Profiles (Luvisols) of the Cserhát Mountains (North Hungary)

Abstract: The clay mineral composition of four brown forest soil profiles (Luvisols) developed on different parent rocks was studied in detail to determine the major clay mineral alteration processes. In the studied profiles a siltstone bedrock weathered to chlorite/vermiculite and vermiculite in a less developed, shallow soil profile, while the major product of soil formation in a clayey, well-developed deep soil is a typical soil montmorillonite with heterogeneous charge distribution. The most possible pathway of clay alteration is illite smectitization via charge reduction, and considerable degradation of smectite in the soil formed on limestone. On the contrary, weathering of andesite parent rock involves the formation of low charged smectite altering to high charged vermiculite during pedogenesis.

Experimental research on sorption of petroleum products from water by natural clinoptilolite and vermiculite

Abstract: Brannvall E., Mažeikienė A., Valentukevicienė M. Experimental research on sorption of petroleum products from water by natural clinoptilolite and vermiculite. Geologija. Vilnius. 2006. No. 56. P. 5–12. ISSN 1392-110X An experimental study of the sorption of petroleum products (PP) from aqueous solutions by natural vermiculite and zeolite (clinoptilolite) was carried out. Two different sizes of zeolite particles were used: 0.63–1.0, 1.0–3.0 mm and 1.0–3.0 mm fractions of vermiculite. Zeolite and vermiculate material was washed and dried at 105 °C in an oven before using it in the filter bed. 40 l of snowmelt water, 1 l of gasoline and 1 l of diesel passed the filter charged with zeolite and vermiculite. Comparison of the results showed that the highest removal of PP from water solution was obtained by using the finest grain-sized zeolite. The removal efficiency was 89.8% and 76.4% respectively for 0.63–1.0 mm and 1.0–3.0 mm particle size zeolite. The highest PP removal efficiency (92.4%) was achieved by using 1.0–3.0 mm particlesized vermiculite.