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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 article, the authors studied the variation of clay mineralogy vertically and laterally within various paralic clay and shale facies within the Desmoinesian strata of Middle Pennsylvanian age.
Abstract: Almost four decades of study of Desmoinesian strata of Middle Pennsylvanian age in south-central Iowa and north-central Missouri have provided the stratigraphic control required to test the variation of clay mineralogy vertically and laterally within various paralic clay and shale facies. Local and regional variations in clay mineralogy within Desmoinesian strata are generally predictable and are in agreement with current knowledge of deltaic deposition. A principal environmental variation within a deltaic system is the change from normal marine salinities in deltaic marine environments to brackish- and fresh-water conditions in the marshy delta plains, in upper interdistributary bays, and within flanking interdeltaic embayments. Changes from marine to nonmarine facies coincide with a decrease in illite, and an increase in kaolin, mixed-layer clays, and in the percentage of expansible layers in the mixed-layer clay. The principal clay detritus entering the area was illite, which underwent various degrees of alteration in different aqueous and subaerial environments within deltaic and interdeltaic areas. Clay-mineral composition alone does not provide unique environmental answers. The distribution of clay-mineral suites within these systems, however, both supports the deltaic-interdeltaic depositional model and can be understood within the context of this framework.
18 citations
TL;DR: The chemical and mineralogical compositions of three tropical soils, before and after permeation with 19-24 pore volumes of acid mine drainage (AMD), were assessed using X-ray diffraction and chemical analyses, in order to consider their potential value as clay liners.
Abstract: The chemical and mineralogical compositions of three tropical soils, before and after permeation with 19–24 pore volumes of acid mine drainage (AMD), were assessed using X-ray diffraction and chemical analyses, in order to consider their potential value as clay liners. After permeation the CEC of one soil (Soil K) was reduced, partly due to structural modification of smectite by AMD. Conversely, the other soils (Soils A and H) showed increased CEC values due to structural changes in mixed layer vermiculite minerals, resulting in the formation of vermiculite as a separate phase in the soils. The specific surfaces of the soils were reduced. AMD caused changes in the variable charge properties of the soils due to the composite effects of soil pH and organic matter reduction and the changes in composition of exchangeable ions. Dolomite, gibbsite, diaspore, magnesioferrite and hydroxy apatite were dissolved from the soils. Chlorite was mildly altered but kaolinite was structurally resistant to AMD attack. Jarosites were, however, formed in all the soils. It was concluded that the tropical soils studied could be effective sinks for zinc and nickel from AMD, but that Soils A and H would be the most desirable clay liners for acid mine waste containment due to their low hydraulic conductivity, high sorptive capacity and compatibility with AMD.
18 citations
TL;DR: In this paper, the authors studied the geochemical behavior of natural nuclides under different physicochemical conditions and concluded that the isotopic signature of water in equilibrium with quartz was approximately in the range from −8.3 to −5.7 V-SMOV.
18 citations
TL;DR: In this article, the surface properties of sepiolite were determined for a natural sample and after surface charge saturation with sodium cations, and the results were similar to those reported in the literature for palygorskite which is the other member of the clay mineral group.
18 citations
TL;DR: The acid/base-treated vermiculite exhibited good properties as a potential adsorbent for tertiary treatment of wastewater in treatment plants, in particular for cationic species as venlafaxine due to facilitation of diffusion of the species to the interlayer gallery upon such treatment.
Abstract: Removal of emerging pollutants, such as pharmaceuticals, from wastewater is a challenge. Adsorption is a simple and efficient process that can be applied. Clays, which are natural and low-cost materials, have been investigated as adsorbent. In this work, raw vermiculite and its three modified forms (expanded, base, and acid/base treated) were tested for removal of a widely used antidepressant, venlafaxine. Adsorption kinetics followed Elovich’s model for raw vermiculite while the pseudo-2nd order model was a better fit in the case of other materials. Equilibrium followed Langmuir’s model for the raw and the acid/base-treated vermiculite, while Redlich-Peterson’s model fitted better the expanded and the base-treated materials. The adsorption capacity of vermiculite was significantly influenced by the changes in the physical and chemical properties of the materials caused by the treatments. The base-treated, raw, and expanded vermiculites showed lower maximum adsorption capacities (i.e., 6.3 ± 0.5, 5.8 ± 0.7, 3.9 ± 0.2 mg g−1, respectively) than the acid/base-treated material (33 ± 4 mg g−1). The acid/base-treated vermiculite exhibited good properties as a potential adsorbent for tertiary treatment of wastewater in treatment plants, in particular for cationic species as venlafaxine due to facilitation of diffusion of the species to the interlayer gallery upon such treatment.
18 citations
Cites background from "The x-ray identification and crysta..."
...…(WNaOH) may be attributed to a phase originating from two(Mg-vermiculite) and one-sheet (Na-vermiculite) (Huo et al. 2012) layers of water (Collins et al. 1992; Marcos et al. 2003; Ruiz-Conde et al. 1996) and interstratification between contracting and non-contracting phases (Walker 1961) (Fig....
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...1996) and interstratification between contracting and non-contracting phases (Walker 1961) (Fig....
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...Such process causes various changes in the material: a decrease in its specific surface area, dehydroxylation of its structure (Barshad 1950; Walker 1961) depriving the material of adsorption sites, and a significant loss of cation exchange capacity that can decrease almost to zero (Földvári 2011; Stefanova 2001)....
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...Such process causes various changes in the material: a decrease in its specific surface area, dehydroxylation of its structure (Barshad 1950; Walker 1961) depriving the material of adsorption sites, and a significant loss of cation exchange capacity that can decrease almost to zero (Földvári 2011;…...
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