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Vermiculite
About: Vermiculite is a research topic. Over the lifetime, 2320 publications have been published within this topic receiving 37142 citations.
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TL;DR: In this article, the weathering stages of K-depleted biotite, Kdepleted phlogopite, and natural biotites were investigated using hydrothermal treatment with A1C13 solution at 200°C for 12 to 72 hours.
Abstract: The weathering stages of K-depleted biotite, K-depleted phlogopite, and natural biotite were investigated using hydrothermal treatment with A1C13 solution at 200°C for 12 to 72 h. Although there were some differences in the degree of weathering of the two K-depleted micas, both first transformed to hydroxy-Al interlayered vermiculite (HIV), which then altered to kaolinite. In case of the natural biotite, the biotite first transformed to a K-depleted mica-like phase, which then altered to kaolinite. The natural biotite had resisted weathering to kaolinite more than did the K-depleted biotite, as expected. The K-depleted phlogopite had less resistance in weathering to kaolinite than the K-depleted biotite. The transformation process changed the color of the micas. The K-depleted biotite changed from greenish-black through yellow to pale gray whereas the natural biotite changed from greenish-black through beige to yellow. However, in the case of K-depleted phlogopite, there was no significant color change during the transformation process. The presence of the interlayer K+ ions and the structural Fe2+ ions in mica appear to have contributed to the differences in the degree of weathering to kaolinite among the micas investigated.
11 citations
TL;DR: In this paper, a study was carried out in a greenhouse of the Centro de Ciencias Agrarias of the Universidade Federal da Paraiba, Northeast Brazil to determine substrate for germination and vigor tests of Peltophorum dubium (Spreng.) Taubert seeds.
Abstract: This work carried out to determine substrate for germination and vigor tests of Peltophorum dubium (Spreng.) Taubert seeds. The experiment was carried out in a greenhouse of the Laboratory of Vegetal Ecology of the Centro de Ciencias Agrarias of the Universidade Federal da Paraiba, Northeast Brazil. Were compared the substrates sand (T 1 ); sand + vermiculite in the ratio of 1:1 (T 2 ), 3:1 (T 3 ) and 1:3 (T 4 ); vegetal soil (T 5 ), vegetal soil + sand in the ratio of 1:1 (T 6 ), 3:1 (T 7 ) and 1:3 (T 8 ), vegetal soil + vermiculite in the ratio of 1:1 (T 9 ), 3:1 (T 10 ) and 1:3 (T 11 ), vermiculite (T 12 ), bioclone® (T 13 ), bioplant® (T 14 ) and plugmix® (T 15 ). The design used was entirely randomized wi th 15 treatments (substrates) and four repetitions of 25 seeds. The evaluation was made through the determination of: percentage of emergency, first counting, index of speed, average time and relative frequency of emergency, length and dry mass of the root and aerial part of seedlings. The results evidenced that the substrates pure commercial vermiculite, bioclone®, bioplant® and plugmix®, well as the mixture sand + vermiculite in the ratio of 3:1, vegetal land + sand in the ratio of 1:1 and vegetal soil + vermiculite in the ratio of 1:3 are less efficient for conduction of germination tests with seeds of P. dubium, while the substrate sand + vermiculite in the ratio of 3:1 is most efficient in detecting differences of vigor in the seeds of the different treatments.
11 citations
TL;DR: In this article, a sample of biotite representing less than 0.025 meq of exchange capacity sorbed over 90 per cent of the cesium and a hydrobiotite with 50 percent vermiculite and representing 1.0 meq-of-capacity sorbed 80 percent of the Cesium.
Abstract: At low cesium ion concentrations extremely high selectivities for cesium are exhibited by layer lattice silicates with unexpanded 10 A c-spacing. The total amount of cesium which can be sorbed by these minerals depends on the edge area and the exchange capacity. At a concentration of 10−5 meq of cesium and 5 meq of sodium, a sample of biotite representing less than 0.025 meq of exchange capacity sorbed over 90 per cent of the cesium and a hydrobiotite with 50 percent vermiculite and representing 1.0 meq of exchange capacity sorbed 80 percent of the cesium.
11 citations
Journal Article•
11 citations
TL;DR: In this article, a 14 A clay mineral with hydroxy-Al interlayers was altered by boiling in 0.2 M A1C13 solution, and the products were examined by X-ray powder and single-crystal diffraction, chemical analysis and thermogravimetry.
Abstract: Biotite was altered by boiling in 0.2 M A1C13 solution, and the products were examined by X-ray powder and single-crystal diffraction, chemical analysis and thermogravimetry. The altered material is a 14 A clay mineral with hydroxy-Al interlayers. It has a stacking sequence characteristic of vermiculite and its silicate layers are similar in chemical composition to trioctahedral vermiculite. The results of extracting the interlayer material with sodium citrate solution, X-ray examinations after heating and thermogravimetry show that the interlayer material is composed of Al associated with OH and H2O. The chemistry and kinetics of the alteration reaction and the orientational between the altered and original biotites are also discussed.
11 citations