Topic
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 paper, a study was made of a Red-Yellow Podzolic soil with particular regard to the properties of dioctahedral vermiculite, one of its major clay minerals.
Abstract: A study was made of a Red-Yellow Podzolic soil with particular regard to the properties of dioctahedral vermiculite, one of its major clay minerals. The soil, Nason silt loam, which is derived from a muscovite schist residuum, was found to be nearly devoid of exchangeable calcium and low in other bases. Although the cation exchange capacity of the B₃ horizon was 25 me. per 100 gm. soil, this horizon contained only 0.08 me. Ca per 100 gm. Clay minerals present were kaolinite, dioctahedral vermiculite, and regularly and randomly interstratified illite-vermiculite. The 14.7A basal spacing of vermiculite from the C₁ horizon moved to 10.5A when the clay was K saturated, but the effectiveness of K saturation decreased from the C₁ horizon through the A horizon where there was only slight collapse. Boiling the clay from the B₁ horizon for 102 hours in 1N KCl caused a change of the 14.7A basal spacing to only 14.2A. However, treatment of the clay in 1N KCl plus 0.1N HCl or treatment with 1N NH₄F altered this spacing to near 10A. The difficultly collapsed mineral had a high internal surface, high base exchange capacity, and low divalent cation content. Easily collapsed dioctahedral vermiculite was made difficultly collapsed by repeated Al saturation and drying. Heat treatment at 800°C. collapsed the 14.7A spacing of the mineral in all horizons to 10.3A. Glycerol solvation caused no increase of the 14.7A spacing. These results together with D.T.A. data support the theory that non-exchangeable Al in the interlayer position in vermiculite restricts collapse of the mineral on K saturation.
128 citations
TL;DR: In this article, the properties of cement-based mortars with vermiculite and silica fume were investigated at ambient and elevated temperatures, and the results indicated that expanded vermiculate aggregate is a good fire resistant material.
128 citations
TL;DR: In this paper, a series of superabsorbent composites were synthesized by copolymerization reaction of partially neutralized acrylic acid on unexpanded vermiculite (UVMT) micropowder using N,N′-methylenebisacrylamide (MBA) as a crosslinker and ammonium persulfate (APS) as an initiator in aqueous solution.
123 citations
TL;DR: The acid properties of acid-modified montmorillonite and vermiculite were determined by pyridine and ammonia adsorption to correlate with the alkylating and dehydrating activity of the activated samples as mentioned in this paper.
Abstract: The acidic properties of acid-modified montmorillonite and vermiculite were determined by pyridine and ammonia adsorption to correlate with the alkylating and dehydrating activity of the activated samples. Treatment of the minerals with different concentrations of hydrochloric acid results in the variation of overall acidity and density of acidic sites. Infrared (IR) spectral and differential scanning calorimetric analyses have revealed the presence of Bronsted and Lewis acid sites on the activated samples. The catalytic activity towards the above reaction has been correlated to the acid strength and density of Lewis acid sites. Treatment of montmorillonite with hydrochloric acid in the range of 0.1 and 0.3 M and vermiculite with 0.2 to 0.3 M seemed to be suitable for the conversion of methanol into olefin-rich hydrocarbons. Acid-activated montmorillonite catalyzed the isopropylation of benzene to a maximum extent of 16%, whereas acid-activated vermiculite gave a maximum conversion of only 4%.
123 citations
TL;DR: Studies with homoionic clays showed that stimulation of respiration and maintenance of favorable pH levels was related to the relative basicity of the exchangeable cations on the clays.
Abstract: Respiration of Agrabacterium radwbacter was stimulated most by certain clay minerals of the 2:1 type (montmorillonite, vermiculite, illite, prochlorite, talc). Some 2:1 minerals (pyrophyllite, verr...
121 citations