Tone und Tonminerale

Lagaly, G.; Köster, Heinrich M.

doi:10.1007/978-3-642-72488-6_1

Cited by 23 publications

(13 citation statements)

References 43 publications

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“…The kaolinite content in Table 1 was determined by infrared spectrometry, which gives both precise and reproducible results (Flehmig & Kurze, 1973). For a rough calculation of the smectite and illite contents, an average chemical composition of these clay minerals was taken from the literature (Newman & Brown, 1987; Lagaly & Köster, 1993). First, the amount of kaolinite (12·3 wt%) was subtracted according to its chemical composition from the chemical composition of the sample given in Table 2.…”

Section: Methodsmentioning

confidence: 99%

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Composition and origin of clay minerals in Holocene sediments from the south‐eastern North Sea

Zuther¹,

Brockamp²,

Clauer³

2000

Sedimentology

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The distribution of clay minerals varies systematically in sediments from Holocene core material taken along a profile from the East Frisian coast to the Doggerbank. The proportion of illite increases with distance from the coast at the expense of kaolinite, whereas slight variations are seen in smectite and chlorite abundances. The chemical composition changes, and the K/Rb ratio and K‐Ar isotopic age of illite increase seawards. This trend results from progressive mixing processes of riverine detritus with Pleistocene fluvioglacial material reworked during the Holocene transgression. However, the clay fluvial flux only became dominant during the decreasing rate of sea‐level rise in the Late Holocene, especially near the shore. For example, modern sediments in tidal flats contain 75% of river‐borne Holocene‐supplied clay detritus, whereas this amount is only 10% in modern marine sediments at the Doggerbank.

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Section: Methodsmentioning

confidence: 99%

“…Despite the fact that the results are not strictly quantitative, they are considered to be reasonable for this study. More accurate determinations of clay mineral contents in fine‐grained samples do not seem to be possible yet (Lagaly & Köster, 1993).…”

Section: Methodsmentioning

confidence: 99%

Composition and origin of clay minerals in Holocene sediments from the south‐eastern North Sea

Zuther¹,

Brockamp²,

Clauer³

2000

Sedimentology

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“…A layer consists of a single sheet of SiO 4 tetrahedra combined into hexagonal rings, with a superimposed dioctahedral gibbsite type sheet of edge sharing octahedra. The silicate and gibbsite layers are held together only through week bindings which cause the cleavage and softness of this mineral [19]. Chemical and mineralogical properties of kaolinite have been reported by Pruett et al [20].…”

Section: Introductionmentioning

confidence: 94%

Neptunium(V) sorption on kaolinite

Amayri¹,

Jermolajev

Reich

2011

Radiochimica Acta

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The sorption behavior of neptunium(V) onto the clay mineral kaolinite was studied in batch experiments under different experimental conditions: [Np(V)] = 7 × 10 −12 -8 × 10 −6 M, solid-to-liquid ratio 2-20 g L −1 , I = 0.1 and 0.01 M NaClO 4 , pH = 6-10, ambient air and Ar atmosphere. The short-lived isotope 239 Np (T 1/2 = 2.36 d) was used instead of 237 Np (T 1/2 = 2.14 × 10 6 a) to study the sorption behavior of Np(V) at environmentallyrelevant concentrations, i.e., 7× 10 −12 M Np. In addition, 239 Np(V) served as tracer to measure sorption isotherms over six orders of magnitude in Np concentration (4.8 × 10 −12 -1.0 × 10 −4 M). The results show that Np(V) sorption on kaolinite is strongly influenced by pH, CO 2 , and ionic strength. The sorption of 8 × 10 −6 M Np(V) at pH 9.0, and ionic strength of 0.1 M NaClO 4 was proportional to the solidto-liquid ratio of kaolinite in the range of 2-10 g L −1 . In the absence of CO 2 , the Np(V) uptake increased continuously with increasing pH value up to 97% at pH 10. Under ambient CO 2 , the sorption of Np decreased above pH 8 up to zero at pH 10. An increase of Np(V) concentration from 7 × 10 −12 to 8 × 10 −6 M resulted in a shift of the sorption pH edge by up to one pH unit to higher pH values. The ionic strength influenced the Np(V) sorption onto kaolinite only in the presence of ambient CO 2 . Under Ar atmosphere the sorption of Np(V) was independent from ionic strength, indicating the formation of inner-sphere complexes of Np(V) with kaolinite. Time-dependent batch experiments at pH 9.0 under ambient CO 2 showed that the sorption of Np(V) on kaolinite is fast and fully reversible over six orders in Np(V) concentration.

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“…Clay particles are negatively charged due to diadochy or isomorphous substitution, incomplete occupation of the positions available for metal ions and release of protons from hydroxides (Lagaly and Ko¨ster, 1993). As a consequence of the negative charge at the surface of clay particles, electrostatic forces exist between the negative surface and exchangeable cations.…”

Section: What Is a Diffuse Double Layer?mentioning

confidence: 99%

Can the diffuse double layer theory describe changes in hydraulic conductivity of compacted clays?

Schmitz

2006

Geotech Geol Eng

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Observations related to modifications of the hydraulic conductivity of compacted soils as a consequence of intentional compositional variation of the percolating fluid are often attributed vaguely to calculated changes in double layer thickness. The same calculated decrease or increase in double layer thickness is interpreted differently, depending on which (unconsciously held) boundary conditions authors take into account. The interpretations of different authors seem to be paradoxical only if the boundary conditions have not been mentioned. On the basis of a literature survey and own previously published test results the different boundary conditions have been grouped and divided into classes. With this division the interpretation of changes in double layer thickness will lead to unique interpretations and predictions of changes in hydraulic conductivity.

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Tone und Tonminerale

Cited by 23 publications

References 43 publications

Composition and origin of clay minerals in Holocene sediments from the south‐eastern North Sea

Composition and origin of clay minerals in Holocene sediments from the south‐eastern North Sea

Neptunium(V) sorption on kaolinite

Can the diffuse double layer theory describe changes in hydraulic conductivity of compacted clays?

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