scispace - formally typeset
Search or ask a question

Showing papers on "Vermiculite published in 1976"


Journal ArticleDOI
TL;DR: The combination of liquid nutrient and peat: vermiculite: gravel (15: 15: 70) medium used at the Climate Laboratory of Plant Physiology Division, DSIR was compared with a range of soilless media and nutrients.
Abstract: The combination of liquid nutrient and peat: vermiculite: gravel (15: 15: 70) medium used at the Climate Laboratory of Plant Physiology Division, DSIR was compared with a range of soilless media and nutrients. Flexibility of the medium was assessed by modifying the ratios of peat: vermiculite: gravel, as well as the source of vermiculite. Growth was found to be either controlled by the pH of the medium, or, in high-gravel-content media, by the pool size of available nutrient. The two sources of vermiculite differed markedly in pH, emphasising that careful quality control is essential for reproducible production of soilless media. Limitations of the standard Climate Laboratory medium are discussed.

74 citations


Journal ArticleDOI
TL;DR: The results of this and previous investigations on artificial and natural weathering of chlorites indicate that oxidation of structural Fe2+ is an important reaction in the alteration of chlorite into vermiculitic products as mentioned in this paper.
Abstract: A IIb orthochlorite (brunsvigite), from the chloritic metabasalt in the Middletown Valley of Maryland, was altered to a regularly interstratified chlorite—vermiculite after four months reaction in saturated bromine water on the steambath. The artificial weathering product resembles the regularly interstratified chlorite—vermiculite in a soil in Adams County, Pennsylvania, that has developed in greenstone similar to the chloritic metabasalt in the Middletown Valley of Maryland. The results of this and previous investigations on artificial and natural weathering of chlorites indicate that oxidation of structural Fe2+ is an important reaction in the alteration of chlorites into vermiculitic products. The results also show that IIb orthochlorites, apparently structurally similar but having different Fe2+ contents may react differently under the same weathering conditions. For example the acid oxidation treatment altered a IIb chlorite (diabantite) directly into a vermiculite, whereas the same treatment altered another IIb chlorite (brunsvigite) into a regularly interstratified chlorite—vermiculite. Detailed investigations of the chlorite structures are probably necessary to determine whether or not these alteration processes are structurally controlled.

67 citations


Journal ArticleDOI
01 Jul 1976-Geoderma
TL;DR: In this paper, the authors studied a deep profile on gneiss from Malaysia and found that the alteration of biotite to halloysite takes place within a few centimeters of the fresh rock (at 18.5 m depth).

32 citations


Journal ArticleDOI
01 Jan 1976-Micron
TL;DR: In this paper, a vermiculite single crystal using hydrogen peroxide has been used to extract very thin (2-3nm) crystal layers and preserve their full ion exchange capacity.

25 citations


Journal ArticleDOI
TL;DR: In this paper, a steady state reaction of apparent equilibrium of K mica + Ca/sup 2 +/ reversible Ca vermiculite + K/sup +/ was indicated by prolonged dissolution extractions from Blount soil clay (from northern Indiana) abundant in dioctahedral mica and vermiculusite, with log K/sub eq/ = 2.92 for the reaction when extrapolated to infinite time.
Abstract: A steady state reaction of apparent equilibrium of K mica + Ca/sup 2 +/ reversible Ca vermiculite + K/sup +/ was indicated by prolonged dissolution extractions from Blount soil clay (from northern Indiana) abundant in dioctahedral mica and vermiculite, with log K/sub eq/ = 2.92 for the reaction when extrapolated to infinite time. From this and published free energies of formation of mica and kaolinite, a mineral phase stability diagram depicting the phase joins of Ca vermiculite, muscovite, and kaolinite was constructed with the solute activity functions pH-pK/sup +/, 2pH-pCa/sup 2 +/, and pSi(OH)/sub 4/. These solute functions for 14-day reactions of calcareous (and dolomitic), poorly drained Harps soil (from central Iowa) fell near the calcite-dolomite-CO/sub 2/-H/sub 2/O phase join, suggesting equilibrium. These functions for Harps soil and the control minerals muscovite, biotite, and (or) vermiculite plus calcite were plotted on the mica-vermiculite stability diagram for various CO/sub 2/ partial pressures. The points fell on the vermiculite-stable side of the mica-vermiculite plane at CO/sub 2/ partial pressures of 0.15 and 0.20 atm (similar to soil air that would exist under frozen soil during winter and early spring; 2pH-pCa/sup 2 +/ approx. = 10.3). They fell on the muscovite-stable side ofmore » the muscovite-vermiculite plane at CO/sub 2/ partial pressures of 0.0001 and 0.001 atm and therefore K/sup +/ would be expected to be fixed. The 2pH-pMg/sup 2 +/ values determined for Harps soil at the various CO/sub 2/ partial pressures plotted either in the Mg montmorillonite stability field or on the Mg-montmorillonite-kaolinite phase join, in concordance with the abundance of montmorillonite and some kaolinite in the medium and fine clay fractions. The solute values for the nearby Clarion soil (upland, noncalcareous) plotted on the montmorillonite-kaolinite join, or with higher CO/sub 2/ partial pressure, in the kaolinite stability area.« less

16 citations




Journal ArticleDOI
TL;DR: In this paper, a commercial exfoliated vermiculite was used as an ion exchange medium for the removal of transition metal ions from dilute aqueous solutions, and a simple favorable-equilibrium model for the breakthrough curve was found to fit the data provided the flow rate was less than 1.5 ml/cm2 min.

13 citations


Patent
James E. Etzel1
22 Dec 1976
TL;DR: An exfoliated vermiculite cation-exchange column is used to remove multivalent heavy metals (copper, zinc, nickel, chromium, etc.) from metal plating wastes.
Abstract: An exfoliated vermiculite cation-exchange column is used to remove multivalent heavy metals (copper, zinc, nickel, chromium, etc.) from metal plating wastes. The exfoliated vermiculite may be either chemically or relatively low-temperature thermally expanded vermiculite ore. It preferably has a cation exchange capacity of over 80 meq/100g. Exfoliated vermiculite particle sizes of less than approximately 10 mesh are preferred as the column packing. The ion-depleted vermiculite from the exchange column after use can be further expanded thermally and used as a lightweight filling material.

13 citations


Journal ArticleDOI
TL;DR: In this article, the formation of illite from expandable three-layer silicates was shown to dominate over formation of smectite from illite in soils formed from unconsilidated sediments with illite-vermiculite-smectite mixtures.
Abstract: Transformation of three-layer silicates through K-release and K-uptake (A review). In soils formed from unconsilidated sediments with illite-vermiculite-smectite mixtures in their clay fractions the clay mineral transformation from illite to vermiculite and smectite between pH 5 and 7 cannot be considered so far as proven on the grounds of available analytical data. Studies of soil profiles showed that the formation of illite from expandable three layer silicates predominates over the formation of smectite from illite. Practically all samples of loess and calcareous tills of the areas discussed contain smectites. K loesses between pH 5 and 7 are probably very small, because K released during the formation of vermiculites from micas is immediately fixed by smectitic layers which are converted to illite. In those soils potential K fixation of the clay fraction (« 2 μ) is lower than in the corresponding parent sediments despite of vermiculite formation in the soils. Further analytical data (X-ray, interlattice-K, K-selectivity, specific surface) support the hypothesis of illitization of smectites during soil formation.

11 citations


Journal ArticleDOI
TL;DR: Fourier syntheses have been used to establish the arrangement of organic molecules in the interlamellar regions of a 16.10 A phase of ornithine-vermiculite and a 6-aminohexanoic acid-ver miculite as discussed by the authors.
Abstract: Fourier syntheses have been used to establish the arrangement of organic molecules in the interlamellar regions of a 16.10 A phase of ornithine-vermiculite and a 16.92 A phase of 6-aminohexanoic acid-vermiculite. The organic cations form two layers parallel to the silicate surfaces in ornithine-vermiculite and in 6-aminohexanoic acid-vermiculite the organic cations form ascending and descending “stairs” from the silicate sheets.

Journal ArticleDOI
TL;DR: The reaction of hexamethylene diisocyanate with the surface of heat-activated vermiculite parallels the reactions with the oxides SiO2, Al2O3, MgO considered individually, which a number of authors have already described.
Abstract: The reaction of hexamethylene diisocyanate with the surface of heat-activated vermiculite parallels the reactions with the oxides SiO2, Al2O3, MgO considered individually, which a number of authors have already described. The fixation ratio is about 5 molecules per 100 A2 area. Nearly one half of the grafted molecules retain a “free” isocyanate function, which is requisite for a subsequent polyaddition of the processed mineral. The interaction with vermiculite occurs according to three principal processes; (i) formation of a surface urethane, (ii) formation of a surface carbamate, (iii) fixation by hydrogen bonds.

Patent
27 Dec 1976
TL;DR: In this paper, a method of nitriding metal parts is described, which requires the metal part to be treated in a body of vermiculite or other porous media containing urea or other suitable nit riding agent.
Abstract: A method of nitriding metal parts is disclosed. A preferred mode requires burying the metal part to be treated in a body of vermiculite or other porous media containing urea or other suitable nitriding agent. Prior to burying, a controlled amount of an aqueous solution of the nitriding agent is absorbed into dry vermiculite; the water of the solution is removed by evaporation leaving a pasty substance coating or impregnating the grains of the vermiculite. The pasty substance coating each vermiculite grain physically forms a thin film on the external particle surface and on the surfaces of its internal porosity; the average film thickness is less than 0.001 inch. The vermiculite bearing the nitriding agent and buried part are heated in a closed container to a temperature at which the agent decomposes at a predetermined slow rate and releases gases bearing nitrogen. Heating is continued for about 4-8 hours at 700°-1300° F (preferably 925°-1050° F for 90% of the applications) to achieve a nitrided case on the metal part of the desired thickness, typically 0.002-0.005 inch thick.

Journal ArticleDOI
TL;DR: In this article, the cation exchange capacity (CEC) of the soils in the Colina district is in interrelation neither with the texture nor the organic matter content, and the apparent inconsistency is largely attributable to the CEC of the coarse fractions of the soil, which contain appreciable amounts of montmorilionite and zeolite with some vermiculite.
Abstract: The cation-exchange capacity (CEC) of the soils in the Colina district is in interrelation neither with the texture nor the organic matter content. This apparent inconsistency is largely attributable to the CEC of the coarse fractions of the soils, which contain appreciable amounts of montmorilionite and zeolite with some vermiculite. The coarse particles containing exchange materials are widely distributed in the soils of central and northern Chile regardless of the soil type, and appear to be rather stable under semi-arid climates.

Journal ArticleDOI
TL;DR: In this paper, the authors observed that the hydroxy-aluminium interlayer may form in the all of discrete vermiculite and interstratified vericulite, and they were different from the mineral assemblages of weathered biotite.
Abstract: The characteristic altered biotites are observed in the weathered granite at eastern part of Tottori prefecture, Japan, From the mineral assemblage, they are classified into following types:(1) Kaolinite+interstratified Chlorite-Vermiculite(2) Kaolinite+Vermiculite + interstratified Chlorite-Vermiculite(3) Kaolinite+Chlorite+Vermiculite+ interstratified Chlorite-Vermiculite.The hydroxy-aluminium interlayer may form in the all of discrete vermiculite and interstratified vermiculite.They are different from the mineral assemblages of weathered biotite.Judging from the mode of occurrence, they were formed from the altered chloritic biotite under the weathering condition.They gives a evidence of hydrothermal alteration before weathering of the parent rock.

Journal ArticleDOI
TL;DR: In this article, the evolution of clay minerals in a Navarre Andosol (Spain) is investigated and the results indicate formation of allophane, evolution of trioctahedral mica to dioctalite and the appearance of 10:14 a interstratified mineral m the lower layer.
Abstract: The evolution of clay minerals in a Navarre Andosol (Spain) is investigated. The results indicate formation of allophane, evolution of trioctahedral mica to dioctahedral illite and the appearance of 10:14 A interstratified mineral m the lower layer. In the top horizons the interstratified mineral changes into vermiculite. The mineral distribution in the profile is indicated.