Showing papers on "Vermiculite published in 2008"
TL;DR: In this article, the behavior of vermiculite and montmorillonite toward adsorption of Cd2+, Pb2+, Zn2+, Mn2+, Cu2+ and Zn 2+ was compared.
233 citations
TL;DR: In this paper, the role of different 2:1 clay mineral populations in soil K absorption and release was investigated using an X-ray pattern decomposition program to quantify peak area modifications induced by K addition and K removal through plant action.
98 citations
TL;DR: In this article, the zeta potential values of vermiculite were measured to determine the effect of pH, clay concentration, and various mono-and multivalent electrolytes including NaCl, KCl, NH4Cl, NaNO3, NaClO4, Na2SO4 and Na2CO3.
Abstract: In this study, the zeta potential values of vermiculite and expanded vermiculite were measured to determine the effect of pH, clay concentration, and various mono- and multivalent electrolytes including NaCl, KCl, NH4Cl, NaNO3, NaClO4, Na2SO4, Na2CO3, Na3PO4·12H2O, MgCl2·6H2O, CaCl2·2H2O, BaCl2, SrCl2·6H2O, CuCl2·2H2O, CoCl2·6H2O, NiCl2, AlCl3, and CrCl3·6H2O on the electrokinetic properties of vermiculite samples. It was found that generally the measured zeta potential values of expanded vermiculite for the studied systems were slightly more negative than that of vermiculite. The pH profiles of vermiculite and expanded vermiculite at acidic, natural, and basic pH values were obtained to determine the effect of time on the pH values of clay suspensions. The zeta potential measurements showed that the surface charge of clay particles was negative in water. The isoelectric point of vermiculite and expanded vermiculite were determined as pH 2.30 and 2.57, respectively. Divalent cations (Mg2+, Ca2+, ...
61 citations
TL;DR: In this paper, a mixture of allophane and vermiculite was used for anti-heat island effect and the pore size distribution in these samples showed a distinct peak at about 1μm irrespective of the mixing ratio.
59 citations
TL;DR: In this paper, a novel cellulose acetate-coated compound fertilizer with controlled-release and water-retention (CAFCW) was prepared, which possessed the three-layer structure.
Abstract: A novel cellulose acetate-coated compound fertilizer with controlled-release and water-retention (CAFCW) was prepared, which possessed the three-layer structure. Its core was water-soluble compound fertilizer granular, the inner coating was cellulose acetate (CA), and the outer coating was poly(acrylic acid-co-acrylamide)/unexpanded vermiculite (P(AA-co-AM)/UVMT) superabsorbent composite. The effects of the amount of acrylamide, crosslinker, initiator, degree of neutralization of acrylic acid (AA), and unexpanded vermiculite concentration on water absorbency were investigated and optimized. The water absorbency of CAFCW was 72 times its own weight if it was allowed to swell in tap water at room temperature for 90 min. Element analysis and atomic absorption spectrophotometer results showed that the product contained 11% nitrogen, 6% phosphorus (shown by P2O5), 9% potassium (shown by K2O), 1% calcium (shown by CaO), and 0.4% magnesium (shown by MgO). Swelling rate, slow-release, and water-retention properties of CAFCW were also investigated. This product with good controlled-release and water-retention capacity, being degradable in soil and environmentally friendly, could be especially useful in agricultural and horticultural applications. Copyright © 2008 John Wiley & Sons, Ltd.
53 citations
TL;DR: In this paper, the authors synthesize rigid polyurethane foam with unmodified vermiculite clay, and the clay is dispersed either in polyol or isocyanate before blending.
Abstract: Nanocomposites of rigid polyurethane foam with unmodified vermiculite clay are synthesized. The clay is dispersed either in polyol or isocyanate before blending. The viscosity of the polyol is found to increase slightly on the addition of clay up to 5 pphp (parts per hundred parts of polyol by weight). The gel time and rise time are significantly reduced by the addition of clay, indicating that the clay acts as a heterogeneous catalyst for the foaming and polymerization reactions. X-ray diffraction and transmission electron microscopy of the polyurethane composite foams indicate that the clay is partially exfoliated in the polymer matrix. The clay is found to induce gas bubble nucleation resulting in smaller cells with a narrower size distribution in the cured foam. The closed cell content of the clay nanocomposite foams increases slightly with clay concentration. The mechanical properties are found to be the best at 2.3 wt% of clay when the clay is dispersed in the isocyanate; the compressive strength and modulus normalized to a density of 40 kg/m 3 are 40% and 34% higher than the foam without clay, respectively. The thermal conductivity is found to be 10% lower than the foam without clay.
52 citations
TL;DR: In this article, the adsorption of Cr(VI) from aqueous solution by Turkish vermiculite was investigated in terms of equilibrium, kinetics, and thermodynamics.
Abstract: The adsorption of Cr(VI) from aqueous solution by Turkish vermiculite were investigated in terms of equilibrium, kinetics, and thermodynamics. Experimental parameters affecting the removal process such as pH of solution, adsorbent dosage, contact time, and temperature were studied. Equilibrium adsorption data were evaluated by Langmuir, Freundlich and Dubinin–Radushkevich (D–R) isotherm models. Langmuir model fitted the equilibrium data better than the Freundlich model. The monolayer adsorption capacity of Turkish vermiculite for Cr(VI) was found to be 87.7 mg/g at pH 1.5, 10 g/L adsorbent dosage and 20°C. The mean free energy of adsorption (5.9 kJ/mol) obtained from the D–R isotherm indicated that the type of sorption was essentially physical. The calculated thermodynamic parameters (ΔG o , ΔH o and ΔS o ) showed that the removal of Cr(VI) ions from aqueous solution by the vermiculite was feasible, spontaneous and exothermic at 20–50°C. Equilibrium data were also tested using the adsorption kine...
45 citations
TL;DR: In this article, a solution casting approach was used to synthesize epoxy nanocomposites with organically modified vermiculite, and the microstructure of the composites as well as the gas barrier properties through solution casting.
Abstract: Epoxy nanocomposites with organically modified vermiculite were synthesized using a solution casting approach and the microstructure of the composites as well as the gas barrier properties through ...
36 citations
TL;DR: In this article, the authors investigated the clay mineral phases in a Rhodic Acrisol soil and discussed their evolution in subtropical conditions using X-ray diffraction (XRD) at the Federal University of Santa Maria, Rio Grande do Sul, Brazil.
Abstract: The purpose of this study was to investigate the clay mineral phases in a Rhodic Acrisol soil and to discuss their evolution in subtropical conditions. Prairie and forest soil profiles were sampled and clay fractions of the parent material and soil horizons analysed by X-ray diffraction (XRD) at the Federal University of Santa Maria, Rio Grande do Sul-Brazil. The XRD results show the presence of interstratified kaolinite-smectite and illite-smectite as well as illite in the parent material. These minerals were also found in the soil samples but with two new phases: hydroxy-aluminium interlayered vermiculite (HIV), which showed incomplete collapse with treatment at 550°C, and a newly formed kaolinite ( d = 7.17 A). Under a subtropical climate and a sandy lithology, HIV and kaolinite appear to be a result of a specific pedogenic clay formation, related to the natural vegetation. Originally, under the prairie area, the intensity of the weathering processes was weak (within 2:1 clay minerals), as only small quantities of kaolinite and Fe oxides, and no evidence of gibbsite, were found.
36 citations
TL;DR: In this paper, the authors examined fresh and weathered granite from drill cores in Tono, Gifu, Japan, to understand weathering products and the mechanisms of chlorite and biotite weathering under low P O 2 conditions.
Abstract: Fresh and weathered granite from drill cores in Tono, Gifu, Japan, was examined to understand weathering products and the mechanisms of chlorite and biotite weathering under low P O 2 conditions. A fresh sample from 365 m depth, a slightly weathered light-green sample from 367 m depth, and a nearly fresh sample from 369 m depth (but with brown stains on fractures), were investigated. The XRD, SEM, EMPA, and TEM analysis of green grains present within chlorite, biotite, and plagioclase grains and in veins was found to be Fe 2+ -rich corrensite [about 40 wt% FeO with Fe/(Fe + Mg) = 0.94]. The corrensite is interpreted to have formed from chlorite and biotite via a dissolution-precipitation mechanism. The 2+ /∑Fe value of 0.69, which, when combined with the presence of amorphous Fe 3+ (hydr)oxides confirmed by TEM, indicates that the Fe 2+ /∑Fe value of corrensite is >0.69. These results indicate that on dissolution of chlorite and biotite, Fe 2+ was transported as Fe 2+ and precipitated as Fe 2+ -rich corrensite and a part of the dissolved Fe 2+ was oxidized to amorphous Fe 3+ (hydr)oxides under low P O 2 conditions. The formation of Fe 2+ -rich corrensite and that of Fe 2+ -rich smectite or vermiculite in the laboratory at 1 atm of P CO 2 and ≤3 × 10 −5 atm of P O 2 (Murakami et al. 2004) suggest that a possible Fe 2+ -bearing product during Precambrian weathering is Fe 2+ -rich sheet silicates but not siderite.
28 citations
TL;DR: The results showed that the nutrient solution composition was significantly modified by contact with zeolite and vermiculite, and to a minor extent with pumice, and the cation concentrations of the fluid phase were sensitive to cadmium addition.
Patent•
27 Aug 2008
TL;DR: In this paper, the authors describe a friction material which is prepared using phenol resin/vermiculite nano composite material as binding agent, which has the advantages of excellent heat resistance property, stable friction parameter, and small heat fading and low wear rate.
Abstract: The invention relates to friction material and a preparation process thereof. Phenol resin/vermiculite nano composite friction material is characterized in that the material is prepared by raw materials that phenol resin/vermiculite nano composite material, carbon fiber, steel fiber, barium sulfate, kaolin, silica dioxide, wollastonite, calcium carbonate, graphite, molybdenum disulphite, butadiene acrylonitrile rubber and hexamethylenetetramine, wherein of each raw material with parts by mass is: 10-20 phenol resin/vermiculite nano composite material, 1-5 carbon fiber, 2-5 steel fiber, 15-20 barium sulfate, 1-5 kaolin, 1-8 silica dioxide, 1-15 wollastonite, 1-15 calcium carbonate, 3-10 graphite, 2-5 molybdenum disulphite, 2-12 butadiene acrylonitrile rubber and 0.8-2 hexamethylenetetramine. Friction material which is prepared using phenol resin/vermiculite nano composite material as binding agent has the advantages of excellent heat resistance property, stable friction parameter, and small heat fading and low wear rate and the like, since the phenol resin/vermiculite nano composite material has the advantages of high heat decomposition temperature and excellent toughness.
TL;DR: In this article, the effect of ground vermiculite and selective leaching on the structure of the vermiculate was studied using 57 Fe Mossbauer spectroscopy, X-ray diffraction, IR and specific surface area (S BET) measurements.
Abstract: The preparation of porous materials from clay minerals by selective leaching is of interest because it yields residues with large specific surface areas that can be used as adsorbents of contaminants or as catalysts. Grinding produces surface modifications and therefore may significantly influence the leaching behavior. The aim of this paper is to study the effect of grinding and leaching on the structure of the vermiculite from Santa Olalla, Spain, using 57 Fe Mossbauer spectroscopy, X-ray diffraction, infrared spectroscopy, and specific surface area ( S BET ) measurements. The study shows that grinding destroys the long range order of the vermiculite, but leaves the local structure in the environment of the Fe atoms intact, at least up to a grinding time of 10 min. The Mossbauer study shows that there is no Fe 3+ in the tetrahedral sheets and that grinding does not lead to a significant oxidation of the structural Fe. Vermiculite ground for 4 min and leached with 1 M HCl solution at 80°C over a 24 h period was decomposed to X-ray amorphous silica with a very large specific surface area ( S BET = 720 m 2 g −1 ) and with total pore volume of 0.586 cm 3 g −1 , whereas an unground sample leached with the same acid concentration yielded a specific surface area of only 504 m 2 g −1 . Most of the Mg 2+ and Al 3+ are removed from the ground sample after leaching with 1 M HCl, while large percentages of Fe 2 O 3 remain with the X-ray amorphous silica. In unground vermiculite leached with 1 M HCl, a considerable amount of vermiculite remains in the residue. A sample ground for 4 min and treated with 0.25 M HCl also shows the typical vermiculite Mossbauer spectrum with an Fe 2+ /Fe 3+ ratio similar to that of the unground vermiculite. The samples ground for 2 or 4 min and treated with 1 M HCl solution have an orange color and, according to the Mossbauer spectra, only Fe 3+ remains. Mossbauer spectra of these samples taken at 4.2 K reveal the presence of akaganeite.
Patent•
12 Nov 2008
TL;DR: In this article, a fire protection coating includes insulation layer 20 including at least 20% free moisture, which is released in the event of a fire to help cool and prolong the efficacy of fire protection.
Abstract: A fire protection coating 10 includes insulation layer 20 including at least 20% free moisture. Insulation layer 20 , preferably a vermiculite/gypsum mixture 26 , is applied such as by spraying a water slurry of the mineral particles to structural member 85 . Before the free moisture can evaporate, diffusion barrier 40 , such as artificial stone formulation 44 , is applied over the moist vermiculite/gypsum mixture 26 . Moisture is retained within vermiculite/gypsum mixture 26 indefinitely and is released in the event of a fire to help cool and prolong the efficacy of fire protection coating 10.
TL;DR: In this article, the behavior of vermiculite as aggregate in fireproof mortars was compared with mortars formulated with two magnesium by-products aggregates which undergo an endothermic decomposition.
Abstract: There exists an increasing concern about the dangers originated in a building in case of fire. In this work the behaviour of vermiculite as aggregate in fireproof mortars was compared with mortars formulated with two magnesium by-products aggregates which undergo an endothermic decomposition. Fire resistance and mechanical properties were evaluated. An optimal mixture of both magnesium by-products as aggregates allows formulating mortars that improve fire resistance at temperatures greater than 450 °C compared with vermiculite mortars. It would be interesting to obtain mortars formulated with magnesium by products and vermiculite to study possible synergic effects.
TL;DR: In this paper, the effect of the pH on B adsorption and the adorption kinetics were compared to raw vermiculite and fitted well with the Freundlich equation.
Abstract: Micron-grade natural vermiculite was modified by several physical and chemical treatments in order to increase the adsorption capacity of this material for B. A thermal exfoliation ( T = 600°C) of pristine material, a chemical exfoliation through reaction with hydrogen peroxide (H2O2 35%), or grafting of a specific B complexant ( i.e. N-methyl-D-glucamine: NMDG) led to an increase in the uptake of B at low initial concentrations of the aqueous solutions ([B] ≈ 5 mg L−1). The more efficient material is the NMDG-grafted clay, for which the adsorption uptake is four times greater than that of raw vermiculite, and reaches 0.04 mmol g−1. For all modified materials, the effect of the pH on B adsorption and the adsorption kinetics were studied and compared to raw vermiculite. Adsorption isotherms were also plotted and fitted well with the Freundlich equation.
TL;DR: In this paper, a natural vermiculite has been modified with titanium and sulfated by the intercalation and impregnation method in order to optimize the acidity of the clay mineral, and characterization of samples were analyzed by X-ray fluorescence (XRF), XRD, nitrogen adsorption isotherms, diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and temperature programmed desorption with ammonia (TPD-NH 3 ).
TL;DR: In this article, total acidity for a series of modified clays obtained from a natural vermiculite is determined through temperature programmed desorption (TPD) using ammonia as probe molecule.
Abstract: Total acidity for a series of modified clays obtained from a natural vermiculite is determined through temperature programmed desorption (TPD) using ammonia as probe molecule. Results obtained for the acidity range from 15.1 to 68.5 meq/100 g.
TL;DR: In this paper, the thermal evolution of Hg(II) adsorbed by two different layer silicates (montmorillonite and vermiculite) via XAS spectroscopy at increasing temperature was analyzed.
Patent•
22 May 2008TL;DR: In this article, a method for preparing an exfoliated vermiculite that comprises the following steps: the step of heating a hydrated non-exfoliating vermiculate at a temperature of between 400 and 600°C for a duration of 3 to 7 hours, thus generating a dehydrated vermicule; the step contacting the de-extraction with a solution containing an interleaving agent degradation with gas release, which can be used in the field of thermal insulation.
Abstract: The invention relates to a method for preparing an exfoliated vermiculite that comprises the following steps: the step of heating a hydrated non-exfoliated vermiculite at a temperature of between 400 and 600°C for a duration of 3 to 7 hours, thus generating a dehydrated vermiculite; the step of contacting the dehydrated vermiculite with a solution containing an interleaving agent degradation with gas release. The invention can be used in the field of thermal insulation.
Patent•
11 Feb 2008
TL;DR: In this article, a method of manufacturing planting soil for slope plantation using water-soluble organic fertilizer, rice straw, wheat flour, vermiculite and the like is provided to obtain planting soil with excellent water holding capacity, air permeability, adhesion properties and root establishment.
Abstract: A method of manufacturing planting soil for slope plantation using water-soluble organic fertilizer, rice straw, wheat flour, vermiculite and the like is provided to obtain planting soil with excellent water holding capacity, air permeability, adhesion properties and root establishment. Planting soil for slope plantation is prepared by the steps of: drying and cutting rice straw into 3.5cm; mixing wheat flour with a diameter of less than 0.03mm and water, heating with steam, drying and grinding; soaking vermiculite with a diameter of less than 4mm in water-soluble organic fertilizer, coating the vermiculite with the ground wheat flour and drying; mixing the remaining organic fertilizer and the ground wheat flour; and mixing general loam, leaf mold compost, ceramic powder, charcoal powder, the vermiculite coated with wheat flour, rice straw and water-soluble organic fertilizer mixed with wheat flour. The general loam has a size of less than 0.8mm in more than 92% of the whole amount and a maximum size of less than 4mm. The leaf mold compost is prepared by mixing rice hulls, cattle dung, oil cake and sawdust.
TL;DR: In this article, the authors examined a Rb fixation method to quantify vermiculite content in California soils derived from granitic and nongranitic alluvium and found that the Rb 1hr fixation was positively and significantly correlated with soil clay content.
Abstract: Quantification of phyllosilicates in soils often depends on a combination of methods, including x-ray diffraction (XRD), cation exchange and fixation capacities, and microscopy. We examined a Rb fixation method to quantify vermiculite content in California soils derived from granitic and nongranitic alluvium. Whole soil (<2-mm) samples were saturated with Rb and heated to 110°C followed by Rb displacement with NH 4 (Rb 110°C ). Fixed Rb was determined directly by instrumental neutron activation analysis. The amount of vermiculite (g kg -1 ) was calculated as fixed Rb content (cmol c kg -1 )/0.154 (based on a cation exchange capacity for vermiculite of 154 cmol c kg -1 ). For comparison, Rb fixation was also estimated after a 1-h incubation (Rb 1hr ) with 2 mmol L -1 RbCl followed by a 30-min extraction with NH 4 Cl. The more rigorous heating treatment (Rb 110°C ) fixed almost 35 times more Rb than the 1-h method. The Rb 110°C fixation was positively and significantly correlated with soil clay content. The XRD data showed, however, that clay fractions were dominated by smectite, mica, and chlorite, while vermiculite, the major K- and Rb-fixing mineral, was a dominant mineral in most silt fractions. The Greene-Kelly test showed that, in soils with smectitic clays, some of the charge originated in the tetrahedral sheet. Silt content was correlated with Rb 1hr fixation but was not correlated with Rb 110°C fixation. Our data suggest that Rb fixation by heating to 110°C overestimates the amount of vermiculite when tetrahedrally substituted smectites are dominant in clay fractions, and includes fixation by minerals in the silt fraction.
Patent•
09 Oct 2008
TL;DR: In this paper, a method for determining amphibole-asbestos in vermiculite is characterized by solid-liquid-separating vermiculate after acid treatment with acid water solution heated up over 90°C.
Abstract: PROBLEM TO BE SOLVED: To provide a method for accurately and efficiently determining in short time the content of amphibole-asbestos in vermiculite as little value as extremely minor quantity below the past detection limit value. SOLUTION: This method for determining amphibole-asbestos in vermiculite is characterized by solid-liquid-separating vermiculite after acid treatment with acid water solution heated up over 90°C, and determining amphibole-asbestos for solid contents. COPYRIGHT: (C)2009,JPO&INPIT
Journal Article•
TL;DR: The results showed that vermiculite is an efficient adsorbent for Cs+ and showed that more than 98% of the total cs+ could be desorbed by vermiculate of 20g/L from Cs solution of 30μg/l(C0) at pH=5.
Abstract: The adsorption of Cs+ by vermiculite and the effect of experimental conditions were investigatedThe results showed that the vermiculite is an efficient adsorbent for Cs+More than 98% of the total Cs+ could be adsorbed by the vermiculite of 20g/L from Cs solution of 30μg/L(C0) at pH=5The adsorption equilibrium was achieved within 5 hours and the optimum pH ranged from 3 to 10No significant differences on Cs+ adsorption were observed at 0～50℃The relationship between the concentration of Cs+ in aqueous solutions and adsorption capacities of Cs+ can be described by the Langmuir adsorption equationThe adsorption rate would decrease when presence of coexistent Na+ and Ca2+ and low concentration(08mg/L～160mg/L) of K+,but it would increase when K+ in a higher concentration(320mg/L～1600mg/L)Additionally,more than 98% Cs+ could be desorbed by 1 mol/L HNO3 solution
Patent•
24 Jan 2008
TL;DR: A mortar for a building material is provided by mixing 40-60% of a dry powder prepared by mixing 35-75wt%of an expandable mineral and 25-65wt% of sulfate anhydride with 30-40wt% water as mentioned in this paper.
Abstract: A mortar for a building material is provided to have excellent heat-insulating, soundproofing, mothproof, and incombustible properties, retain proper strength, and hardly form cracks after application A mortar for a building material is obtained by mixing (A) 40-60% of a dry powder prepared by mixing 35-75wt%of an expandable mineral and 25-65wt%of sulfate anhydride with (B) 40-60wt%of water The expandable mineral is selected from expanded perlite or expanded vermiculite The expanded perlite is obtained by grinding perlite ore to have a particle size of 10-12 mesh, and heating the ground perlite at 900-1,200 °C for 10-20 minutes to expand the particle size to 06-5 mm The expanded vermiculite is obtained by coarsely grinding a vermiculite ore, sieving the ground vermiculite, and heating the sieved vermiculite at 800-1,100 °C for 15-30 minutes to expand the particle size to 06-5 mm
Patent•
26 Aug 2008
TL;DR: An artificial stone is provided to lower a production cost and express a vividly dark color by reducing the amount of white inorganic material powder, and to show various and natural color tones and patterns as discussed by the authors.
Abstract: An artificial stone is provided to lower a production cost and express a vividly dark color by reducing the amount of white inorganic material powder, and to show various and natural color tones and patterns. An artificial stone includes 100 parts by weight of vermiculite, 0.5-5 parts by weight of inorganic powder, and 5-20 parts by weight of an organic binder. The inorganic powder is any one selected from aluminum hydroxide, silica, and calcium carbonate, or a mixture of two or more. The organic binder is a thermosetting resin obtained by mixing 100 parts by weight of epoxy resin with 5-80 parts by weight of phenol resin. The vermiculite has a particle size of 1-40 mm.
Journal Article•
TL;DR: In this article, the cation exchange capacity (CEC) of vermiculite concentrate is measured by ammonium chloride- ethanol method and it is shown that vermiculate particles must be sufficiently dispersed and wetted to make the vermicule interlayer cations entirely exchange with NH4 in ammonium- chloride-ethanol solution.
Abstract: The cation exchange capacity (CEC) of vermiculite concentrate is measured by ammonium chloride- ethanol method.The results show that vermiculite particles must be sufficiently dispersed and wetted to make the vermiculite interlayer cations entirely exchange with NH4 in ammonium chloride-ethanol solution.The formic acid content must be deducted when NH_4~+ content is measured by formol titration method.To get accurate results,the titrated solution of ammonium chloride-ethanol should not be heated before it is titrated with NaOH standard solution.The measured CEC of vermiculite concentrate is 60.8824×10~(-3) mol/100 g.