Showing papers on "Vermiculite published in 2004"

Effects of straw and silicon soil amendments on some foliar and stem-base diseases in pot-grown winter wheat

Abstract: Four foliar and two stem-base pathogens were inoculated onto wheat plants grown in different substrates in pot experiments. Soils from four different UK locations were each treated in three ways: (i) straw incorporated in the field at 10 t ha−1 several months previously; (ii) silicon fertilization at 100 mg L−1 during the experiment; and (iii) no amendments. A sand and vermiculite mix was used with and without silicon amendment. The silicon treatment increased plant silica concentrations in all experiments, but incorporating straw was not associated with raised plant silica concentrations. Blumeria graminis and Puccinia recondita were inoculated by shaking infected plants over the test plants, followed by suitable humid periods. The silicon treatment reduced powdery mildew (B. graminis) substantially in sand and vermiculite and in two of the soils, but there were no effects on the slight infection by brown rust (P. recondita). Phaeosphaeria nodorum and Mycosphaerella graminicola were inoculated as conidial suspensions. Leaf spot caused by P. nodorum was reduced in silicon-amended sand and vermiculite; soil was not tested. Symptoms of septoria leaf blotch caused by M. graminicola were reduced by silicon amendment in a severely infected sand and vermiculite experiment but not in soil or a slightly infected sand and vermiculite experiment. Oculimacula yallundae (eyespot) and Fusarium culmorum (brown foot rot) were inoculated as agar plugs on the stem base. Severity of O. yallundae was reduced by silicon amendment of two of the soils but not sand and vermiculite; brown foot rot symptoms caused by F. culmorum were unaffected by silicon amendment. The straw treatment reduced severity of powdery mildew but did not detectably affect the other pathogens. Both straw and silicon treatments appeared to increase plant resistance to all diseases only under high disease pressure.

Seed treatments to advance greenhouse establishment of beet and chard microgreens

Abstract: SummarySeed treatments to advance the establishment of table beet or chard (Beta vulgaris L.) for greenhouse microgreen production were examined. While germination percentage was little affected, appreciable germination advancement in both crops was achieved using all seed treatments of matric priming (–1 MPa at 12°C for 6 d in fine vermiculite) or various soaks (water, 20°C for 48 h; hydrogen peroxide, 0.3% at 20°C for 48 h; hydrogen chloride, 0.3 M at 20°C for 2 h; or sodium hypochlorite, 4% at 20°C for 3 h). The most pronounced seedling emergence advancement, however, was gained by germinating seeds in fine grade vermiculite and sowing the germinated seed plus vermiculite mixture. No additional advancement in seedling emergence or growth was achieved by priming or soaking the seeds in hydrogen peroxide before germinating the seeds in the vermiculite. Germinating the seeds in shallow (c 4 cm deep) vermiculite (150% initial water, c 1 seed :3 vermiculite dry weight ratio, 27°C) for 2 d (table beet) or 3 ...

Comparative study of ground and sonicated vermiculite

Abstract: The aim of this work is to compare the effects of grinding and ultrasonic treatment on vermiculite. Sonication produces a drastic change in particle size (mass median particle diameter 2.4 μm, layer thickness 38 nm), while the resulting material is crystalline as assayed by X-ray diffraction patterns. The TEM study shows that the sonicated vermiculite consists of nanometric flakes. On the other hand, grinding produces particles with medium diameter in the range of about 9 μm and very broad particle size distribution. X-ray and TEM studies of ground sample show an important alteration with grinding time. Prolonged grinding of vermiculite produces the loss of long-range order and eventually an amorphous product is obtained. The results show that grinding treatment produces a decrease of particle size, amorphization and agglomeration of the particles, whereas the ultrasound treatment only produces a decrease of particle size.

Smectite in Spodosols from the Adirondack Mountains of New York

Abstract: Clay mineral analysis of Spodosols collected from the Adirondack Mountains reveals that smectite is common in the forest floor and uppermost soil horizons (the O, A and E horizons) and probably forms from the transformation of vermiculite via a low-charge vermiculite intermediate. The conversion of vermiculite to smectite occurs in the upper part of the soil profile where organic acids and strong inorganic acids (derived from atmospheric deposition) combine to create an intense weathering environment. X-ray diffraction (XRD) and chemical data for the clay fraction indicate that both the smectite and the low-charge vermiculite are Al-rich and dioctahedral. The smectite appears to be a beidellite. Transformation of vermiculite to smectite may have progressed in these acidic horizons by net layer-charge reduction resulting from the progressive substitution of Si for Al. The parent material for the soil clays was probably biotite, but little remains in these soils.

Clay minerals and the development of Quaternary soils in central Italy

Abstract: Clay mineral analysis is widely used to characterize soil parent material and to relate it to the bedrock. When it is applied to a soil profile, it can give a ‘genetic signal’ of mineralogical transformations due to soil-forming processes. In this study, ten selected soil profiles in Montagnola Senese, central Italy, were analyzed for genetic signals of soil ageing, eluviation and illuviation, fragipan formation, and other processes. In previous investigations, the parent materials of benchmark soils of the area have been dated to gain an understanding of the Quaternary geomorphological evolution, which spans a time ranging from early Pleistocene to Holocene. The number of profiles selected allowed a statistical analysis of the parameters. Illite and kaolinite are the most quantitatively important phyllosilicates in the soils studied. The other clay minerals found are vermiculite, hydroxy-interlayered vermiculite (HIV), illite–HIV and illite– chlorite mixed layers, and chlorite. Soil ageing is characterized by a change in clay mineral composition that increases with age. Argilluviation is marked by a preferential accumulation of kaolinite in illuvial horizons, while formation of tongues in fragipans does not cause any significant difference in clay mineral composition between bleached and stained parts of the horizons. Furthermore, bulk density of fragipans is not related to clay mineral content. On the other hand, large bleached masses in more mature soils contain more kaolinite and vermiculite than the surrounding mass. The trends in the contents of clay minerals through the soil horizons confirm the two types of lithological discontinuities that were predicted during the field survey.

Growth responses of seminal roots of wheat seedlings to a reduction in the water potential of vermiculite

Abstract: We examined the elongation rate, water status and solute accumulation in the seminal roots of wheat seedlings (Triticum aestivum L.) that were growing in vermiculite with a water potential (Ψw) ranging from −0 03 to −1 10 MPa. The elongation rate of the primary seminal root was similar to that of the first pair of seminal roots but that of the second pair of seminal roots was lower at all values of Ψw tested. The elongation rate was highest in vermiculite with a Ψw of −0.03 MPa but did not decrease significantly until the Ψw was reduced to −0.15 MPa. Further reductions in Ψw reduced the elongation rate markedly. The Ψw of mature tissues was always similar to that of vermiculite. The osmotic potential (Ψo) decreased to the same extent as the decrease in Ψw. Thus, the turgor pressure (Ψp) remained unchanged even in vermiculite with a low Ψw. In elongating tissues, Ψw and Ψo were far lower than they were in mature tissues and, thus, reductions in turgor were not significant. Even when the Ψw of vermiculite changed, there were no consistent changes in terms of a difference in Ψw between elongating plus mature tissues and vermiculite. There were also no consistent changes in levels of osmotica, calculated using the van’t Hoff’s law, in the elongating tissues but the levels in mature tissues increased in vermiculite with a low Ψw. Our results suggest that (1) reductions in root elongation in vermiculite with a low Ψw were caused by reductions in the extensibility and/or increases in the yield threshold of cell walls and by reductions in the hydraulic conductivity of the tissues; and (2) a seminal root regulates its growth to keep turgor pressure unchanged.

Hygrothermal properties of glass fiber reinforced cements subjected to elevated temperature

Abstract: The effect of elevated temperatures on basic hygric and thermal properties of three types of glass fiber reinforced cement composites (GFRC) is analyzed in the paper. The main difference in the composition of particular GFRC is the use of wollastonite and vermiculite in two of them instead of usual sand aggregates. The composites containing wollastonite and vermiculite are found to have about four times lower thermal conductivity and two to three times lower thermal diffusivity in room temperature conditions. After heating the samples to 800°C and subsequent cooling, a decrease in room-temperature thermal conductivity as high as 50% and an increase in moisture diffusivity in the range of one to two orders of magnitude are observed for all types of studied materials. The application of wollastonite and vermiculite exhibits a positive effect on the high temperature linear thermal expansion coefficient. On the other hand, for temperatures higher than 450°C the thermal diffusivity of materials with wollastonite and vermiculite is higher than of common GFRC with sand aggregates.

Method for producing mineral water

Abstract: PROBLEM TO BE SOLVED: To provide a method for producing mineral water which contains sufficient air (oxygen) and has high plant-activating ability, by mixing micro bubbles into the mineral water.SOLUTION: The method for producing mineral water comprises a step of pulverizing vermiculite; a step of mixing the pulverized vermiculite with a concentrated sulfuric acid; a step of diluting a mixture of the vermiculite and the concentrated sulfuric acid; a step of separating the diluted mixture into a filtrate and a dehydrated cake; and a step of mixing micro bubbles into the filtrate.SELECTED DRAWING: Figure 1

Vermiculite surface structure as imaged by contact mode AFM

Abstract: The {001} surfaces of three vermiculite samples from different geological origins have been examined with an atomic force microscope (AFM) in the contact mode of operation. Images of the basal O plane of the sheet of tetrahedra and the plane of OH groups of the octahedral sheet of the Mg-interlayer were recorded. Differences in the appearence of the interlayer hydroxide surface of the three vermiculites are attributed to their variable Mg-interlayer contents and the presence of biotite-vermiculite mixed-layer mineral associated with vermiculite. The mean unit cell dimensions for both cleavage halves in each sample are consistent with those of the bulk structure within experimental error, indicating that the surface structure of neither the tetrahedral sheet, nor the OH plane of the sheet of interlayer show noticeable reconstruction.

Clay mineral associations in soils formed under Mediterranean-type climate in South Africa

Abstract: The objective of the study was to determine clay mineral associations in soils of the winter rainfall area of South Africa and to relate them to dominant soil-forming factors. Clay mineral compositions from 69 profiles, involving 190 samples, were determined by means of X-ray diffractometry. Mica proportions decreased predominantly (R2 = -0.59) through weathering. The exchangeable potassium percentage (EKP), however, also played a significant role and mica was absent from soils with EKP = 0. Smectite, vermiculite and hydroxy-interlayered vermiculite (HIV) occurred in 60, 28 and 62 samples respectively, and illite/smectite (I/S) in 44. The number of samples containing swelling clays decreased with increasing rainfall while the percentage of HIV increased. The most important agricultural aspect is that many, if not all, vermiculites, smectites and l/S phases, are highly K-fixing. As a result of the geothermal history of the area, chlorite and mica must have been by far the dominant minerals in the parent ro...

Sorption of Strontium on Zirconia Modified Vermiculite

Abstract: tium on vermiculite and ZrMV increased with increase in pH and lowering concentration of Sr 2+ . The rate of uptake of strontium by ZrMV was found to be much faster than that for vermiculite. The distribution coefficient of strontium on ZrMV is of the order of 10 4 mL/g at pH 3, and the amount of strontium sorbed on ZrMV was always found to be much higher than that on the parent clay. The sorption data were fitted to Langmuir adsorption model for obtaining the sorption capacity of the sorbent. Increase of temperature increases the distribution coefficient of strontium on both ZrMV and vermiculite. Distribution of strontium on ZrMV was also determined from the groundwater samples obtained from the waste disposal site at Kalpakkam.

Na biotite and intermediate Na-K biotite in schists from the Betic Cordilleras (Spain)

Abstract: Submicroscopic intergrowths of K biotite, Na biotite and intermediate Na-K biotite from a schist near Malaga (Betic Cordilleras, Spain) were discovered using high-resolution transmission electron microscopy and analytical electron microscopy. The sample was also studied with X-ray diffraction, electron microprobe analysis, and scanning electron microscopy. Scanning electron microscopy revealed that the Na-enriched biotite is concentrated in albite-rich microdomains, albite being partially replaced by biotite. These images also revealed that both K and Na-K biotite grains appear locally retrograded to kaolinite. Transmission electron microscopic data indicated that K biotite, Na biotite and Na-K biotite form parallel or subparallel packets with interfaces parallel to the basal planes of biotite. Potassium biotite forms thick packets, chemically homogeneous, with a basal spacing of 10.1 A. Sodium biotite also occurs as chemically homogeneous stacks of layers with a 9.78 A periodicity. Sodium-K biotite shows, on the contrary, variable composition and basal spacings intermediate between K and Na biotites. Analytical electron microscopic data revealed important chemical differences between Na and K biotites, which affect both the tetrahedral and the octahedral sheets. Both electron microprobe analysis and analytical electron microscopy indicated that the trioctahedral micas show relatively low interlayer occupancy, suggesting the presence of H 3 O + replacing the interlayer cations. Partial hydration of biotite explains the presence of a weak 14 A reflection in the X-ray patterns. Both chemical and textural data suggested that these trioctahedral micas grew during a common prograde metamorphic episode, the phases with intermediate composition probably being metastable.

Effect of sonication on the thermal decomposition of ammonium vermiculite as studied by TG-MS hyphenated technique

Abstract: The thermal decomposition of the ammonium exchanged vermiculite takes place in three steps. A strong correlation exists between the mass loss of ammonia and water suggesting a simultaneous release. It is proposed that proton transfer from the ammonium ion to the hydroxyl units results in this simultaneous release. This behaviour could be explained by a mechanism where a resulting proton, produced by the release of ammonia out of ammonium cation, combines with a structural hydroxyl to form water. Sonication produces a substantial reduction in the particle size of the vermiculite sample. Thus, the macroscopic particle size of the untreated material is drastically reduced to the micrometers range while the structure as assayed by XRD remains unchanged. The particle size reduction produced by the sonication treatment modifies the thermal decomposition profile, mainly the mass percentages of the different steps.

Mechanism of phosphorus purification in some kinds of substrates constructed wetland systems.

Abstract: The mechanism of sewage phosphorus purification by 7 kinds of substrate materials (sand, zeolite, vermiculite yellow-cinnamon soil, Xiashu loess, fly ash and flag) in constructed wetland was studied. Flag and fly ash had very good removal effect of phosphorus, followed by vermiculite, yellow-cinnamon soil and xiashu loess, the zeolite and sand had the less effect. The mechanism as mentioned above was mainly chemical mechanism, so the more the content of total, oxidized and water soluble Ca, the more the solidified calcium phosphate. Under the condition of higher pH, the solidified calcium phosphate was mainly the phosphates of octo and ten calcium hard to dissolve, so favorable to phosphorus purification. The more contents of free oxides of Fe, Al, as well as of colloid oxides of Fe, Al in substrate, the more amounts of solidification phosphates of Fe, Al; the phosphorus purification capacity of the substrate was more strange. The ratio of desorption and saturated adsorption of phosphorus as mentioned above was very low except sand substrate. Strengthening the substrate management in constructed wetland, the second time pollution of phosphorus on waters environment would not be formed generally in constructed wetland.

Bed soil for paddy field containing peat moss, vermiculite, diatomaceous earth and zeolite powder

Abstract: PURPOSE: A bed soil composition containing peat moss, vermiculite, diatomaceous earth and zeolite powder is provided. It is light as compared to conventional bed soil, excellent in water retention properties, water drainage properties and air permeability and reduces the seedling raising period. CONSTITUTION: The bed soil composition comprises 10 to 20% by volume peat moss, 10 to 15% by volume of coconut coir pith, 45 to 60% by volume of vermiculite, 8 to 15% by volume of diatomaceous earth and 4 to 10% by volume of zeolite powder, based on the total volume of the composition. The composition can contain general additives containing a pH adjuster, bactericidal components, solid fertilizer, liquid fertilizer, a synergist and a wetting agent.

Molded products using vermiculite and manufacture thereof

Abstract: PURPOSE: Provided are molded products, industrial and constructional materials, which prevent flames and generation of toxic gas, emit far infrared rays, and improve workability by using vermiculite with characteristic properties such as incombustibility, heat insulation and lightweight. CONSTITUTION: The manufacturing method of molded products comprises the steps of: (i) grinding vermiculite to an effective size according to use; (ii) firing at 200-850deg.C in the reductive atmosphere in a blast furnace to expand the volume of ground vermiculite; (iii) adding an adhesive containing 6-10wt.% of boric acid, 11-15wt.% of borax, 3-5wt.% of incombustible sodium silicate solution and 70wt.% of water; (iv) heat-processing mixed materials to a plat shape with a roller of 100-350deg.C for 3-10min; (v) moldering by rapid heating at 250-300deg.C in pressing; (vi) drying in the air for 24-48hrs. Also, the step (v) comprises the first drying at 100-200deg.C and the second drying by repeating hot blowing(50-200deg.C of wind at a rate of 0.3-5m/sec) and discharging. The resultant molded products are used as insulating materials such as filling materials used in fire door or sandwich panel and vermiculite board.

Study of Removal Rate of Ammonium by Vermiculite Adsorption

Abstract: The present study was conducted to determine the adsorption capacity of NH_4-N from wastewater by vermiculite and to test the influence of pH value, temperature, ammonium concentration and applied quantity of vermiculite minerals on the removal rate of ammonium. The saturated ammonium adsorption capacity (Q_0) of vermiculite was found to be 20.83 mg·g~(-1). Within the pH rang 2.0～6.0, the adsorption quantity increased with increasing pH value, and then decreased with a further rise of the value from 6.0 to 9.0. The temperature had a negative influence on ammonium adsorption within the rang between 10℃ and 35℃. When initial concentration of ammonium was lower than 50 mg/L, the ammonium removal rate was enhanced by an increase in applied quantity of vermiculite minerals. The basic data and theoretical discussion from the present study support the use of vermiculite as a new medium for removal of nitrogen in wastewater treatment.

Cesium and Strontium Uptake to Clay Minerals and Their Weathering Products in a Caustic Waste

Abstract: Weathering behavior and contaminant (Sr and Cs) uptake by specimen clays (illite, vermiculite, montmorillonite and kaolinite) and their secondary solid phase products were studied in batch systems under geochemical conditions characteristic of leaking tank waste at the Hanford Site in WA (0.05 M AlT, 2 M Na+, 1 M NO3 -, pH {approx}14, Cs+ and Sr2+ present as co-contaminants). Time series experiments were conducted from 0 to 369 days, with initial Cs+ and Sr2+ concentrations ranging from 10-5 to 10-3 M. Cesium sorption after 369 d reaction was the greatest in the order of vermiculite, illite, montmorillonite and kaolinite at 10-3 M Cs/Sr. In the case of Sr, vermiculite showed highest Sr sorption and was followed by kaolinite, montmorillonite and illite at highest loading Cs/Sr after 369 d. Secondary phase products were feldspathoid sodium aluminum nitrate silicate, sodium aluminum nitrate silicate hydrate, Na-Al chabazite and zeolite X in weathered clays. Discrete Sr single phases were found in kaolinite and illite systems after 369 d at 10-3 M Cs/Sr.

Mineral material fire extinguishing dry powder

Abstract: A fire-extinguishing dry powder of mineral material is prepared from vermiculite and additive through crushing vermiculite, proportionally mixing with additive, drying at 80-100 deg.C for 1-1.5 hr, adding additive and screening. It features that when it is heated to 180 deg.C, its volume can expand by 6-10 times while become a new substance to cover on the burning object for isolating oxygen.

Phosphorus adsorption of some clay minerals and soils

Abstract: Phosphorus adsorption of kaolinite,montmorillonite,attapulgite,vermiculite and zeolite and their affecting factors were studied through experiment on isotherm P adsorption and post-saturation-adsorption P release.Results show that vermiculite is theoretically the highest in P saturation adsorption capacity,being 3 473 mg·kg~(-1) and followed by attapulgite,yellow cinnamon soil,montmorillonite and Xiashu loess,zeolite and kaolinite.The last is the lowest in theoretic P saturation adsorption capacity,lingering at 554 mg·kg~(-1).The P adsorption capacity of these clay minerals and soils was mainly influenced by their contents of reactive Ca,Fe and Al,but it was not much affected by soil pH value,CEC and specific surface of the clay minerals and soils,because the main mechanism of the adsorption is chemical sorption.Meanwhile another experiment on desorption of phosphorus from these clay minerals and soils saturated with phosphorus was also conducted.Results show that P release from the clay minerals and soils after P saturation adsorption was very limited.

Revisão de intemperismo de micas.

Abstract: The micas are rock forming mineral of the phyllosillicates group. The weathering of these minerals is fundamental in the understanding of potassium, silicon and magnesium liberation processes to the soil. the existent studies shown that the main factors that control the micas weathering are the pH of the solutions, the temperature, the size of the particles and the superficial area. The micas weathering is incongruous, in other words, always new minerals are formed as dissolution products, as vermiculite, kaolinite and goethite. These products can precipitate in the surface of the mica, especially the iron oxides of iron, and they impede the contact with its surface, reducing the dissolution kinetics. The structure of the micas is also a decisive factor in the dissolution kinetics. The dissolution kinetics presents the following decreasing order: phlogopite, biotite, and muscovite.

A high performance fermentation process for citric acid production by Aspergillus niger NGGCB-101, using vermiculite as an additive in a stirred bioreactor

Abstract: The present study describes the use of vermiculite for enhanced citric acid productivity by a mutant strain of Aspergillus niger NGGCB-101 in a stirred bioreactor of 15.0 l capacity. The maximum amount of citric acid (96.10 g/l) was obtained with the control 144 h after mycelial inoculation. To enhance citric acid production, varying levels of vermiculite were added as an additive into the fermentation medium. The best results were observed when 0.20 μg/l vermiculite was added into the medium 24 h after inoculation resulting in the production of 146.88 g citric acid monohydrate/l. The dry cell mass and residual sugar were 11.75 and 55.90 g/l, respectively. Mixed mycelial pellets (1.08–1.28 mm, dia) were observed in the fermented culture broth. When the culture grown at different vermiculite levels was monitored for Qp, Qs and qp, there was a significant enhancement (P≤ 0.05) in these variables over the control (vermiculite-free). Based on these results, it is concluded that vermiculite might affect mycelial morphology and subsequent TCA cycle performance to improve carbon source utilization by the mould, basic parameters for high performance citric acid fermentation.