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The x-ray identification and crystal structures of clay minerals
01 Jan 1961-
About: The article was published on 1961-01-01 and is currently open access. It has received 966 citations till now. The article focuses on the topics: Clay minerals.
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TL;DR: In this paper, the authors used the optimised three-step BCR sequential extraction procedure to assess the mobility of selected elements in soil profiles from Croatian and Slovakian karst terrains.
Abstract: With the use of the optimised three-step BCR sequential-extraction procedure it was possible to assess the mobility of selected elements in soil profiles from Croatian and Slovakian karst terrains. The soils in the Croatian karst were enriched in Cr, Ni, V, Mn, Cu, Cd and Mo, while soils from the Slovak Karst had high Pb and Zn concentrations. It was determined that the elements were most readily mobilised from the topsoil and the degree of mobility decreased with depth. Cr and Ni were mainly bound to the residual fraction, and Pb in the oxidisable fraction. Cu mobility was high in samples treated with agrochemicals throughout the soil profile.
36 citations
01 Jan 1962
TL;DR: In this paper, the authors proposed a method to solve the problem of "uniformity" and "unweighting" of data points.__ _______________________________________________________, i.e.,
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36 citations
TL;DR: In this article, a simplified synthetic system of MgO-Al2O3-SiO2-H2O was investigated under conditions of 1 and 2 Kb water pressure and temperatures between 300 and 700°C.
Abstract: Twenty-six compositions in the system MgO-Al2O3-SiO2-H2O were investigated under conditions of 1 and 2 Kb water pressure and temperatures between 300 and 700°C. The solid solution for 7 A and 14 A chlorites has been delimited as well as that of the expanding phases (tri- and dioctahedral montmorillonites and expanding chlorites). Negative slopes were found for the transformation montmorillonite → expanding chlorite, and expanding chlorite → chlorite+quartz and a positive slope for 7A → 4 A transformation. The relative positions of the reactions chlorite+quartz → cordierite+talc, chlorite+andalusite → cordierite and chlorite+corundum → cordierite+spinel are located between 500 and 65°C. Cell dimensions of the synthetic chlorites can be correlated with their chemical composition. Solid solution in synthetic minerals compares well with 325 analysis of natural minerals from the literature, indicating that the chemiographic relations between phases in the simplified synthetic system are applicable to natural mineral assemblages. The phase relations indicate that at low temperature the 7A aluminous chlorite is not stable with quartz or another silica phase.
36 citations
TL;DR: In this article, the maximum crystal radius Rn of ice in hollow wet chrysotile tubes is established by thermoporometry to be between 2.8 and 3.2 nm, and the internal pore volume Vn of the tubes to be 0.008 and 0.02 ml/g.
Abstract: The maximum crystal radius Rn of ice in hollow wet chrysotile tubes is established by thermoporometry to be between 2.8 and 3.2 nm, and the internal pore volume Vn of the tubes to be between 0.008 and 0.02 ml/g. The hollow tubes of chrysotile and, for comparative reasons, small plates of talc, are hydrothermally synthesized at temperatures between 563 and 600 K and at pressures between 75 and 120 hPa. Size and shape of the pores can be varied by changing the Mg/Si molar ratios in steps of 3/1.5 and 3/2 for chrysotile and 3/3.6 and 3/4 for talc. The tubular morphology of the aggregates dried at 393 K is investigated by 1) transmission electron microscopy (TEM), 2) nitrogen adsorption and desorption at 77 K, and 3) diffuse reflectance infrared fourier transformed spectroscopy (DRIFTS). The radius within the hollow tubes, Ri, is between 2.5 and 4.0 nm as measured by TEM, and between 2.8 and 3.2 nm as determined by nitrogen adsorption and desorption. The measured radii agree well with the value calculated from crystallographic data, which is smaller than 5.3 nm. Within the dried aggregates the tubes are clustered in regular patterns, in which each tube is surrounded by six other tubes. The external radius, Ro, between the clustered tubes is from 1.6 to 2.9 nm as observed by TEM, and from 1.8 to 2.3 nm by N2 adsorption and desorption. The external radius is not measured by thermoporometry. Where thermoporometry only measures the average pore size and pore volume within the tubes, TEM and N2 adsorption and desorption additionally provide the corresponding values between the tubes. A third pore radius, 5 to 20 nm between the clusters of chrysotile tubes, is established with N2 adsorption and desorption.
36 citations
Cites background from "The x-ray identification and crysta..."
...14 o f c l inochrysot i le wi th the angle/~ o f 93 ~ (Brown, 1961; Zussman et aL, 1957)....
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TL;DR: In this article, different alkali and alkaline earth cation forms of bentonite clay were exchanged with protonated mono-, di- and triethanolamine compounds, to study the effect of the exchanged ammonium cations on the structure characteristics, thermal behavior, surface properties and CO 2 adsorption capacities of the material.
36 citations