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Author

G. Brown

Bio: G. Brown is an academic researcher. The author has an hindex of 2, co-authored 2 publications receiving 3616 citations.

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01 Jun 1982
TL;DR: In the years 1930-1950 clay mineral identification involved mainly a combination of X-ray powder diffraction and chemical analysis with some assistance from other techniques, notably differential thermal analysis.
Abstract: In the years 1930—1950 clay mineral identification involved mainly a combination of X-ray powder diffraction and chemical analysis with some assistance from other techniques, notably differential thermal analysis. In the period 1950—1970 additional procedures have emerged including infrared analysis, electron optical methods and a variety of thermal methods. These procedures are now treated in other monographs sponsored by the Mineralogical Society and in many other publications. Despite the availability of other techniques, X-ray diffraction remains a basic tool for studying minerals and we hope that this monograph will continue to serve, as did the previous editions, both those concerned with the more academic aspects of clay mineralogy and also those, such as geologists, civil engineers and soil scientists, for whom identification and quantitative estimation of the minerals in natural clayey materials is a practical requirement.

3,090 citations


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Journal ArticleDOI
22 Apr 1983-Science
TL;DR: The intercalation of polynuclear hydroxy metal cations and metal cluster cations in smectites affords new pillared clay catalysts with pore sizes that can be made larger than those of conventional zeolite catalysts.
Abstract: Recent advances in the intercalation of metal complex cations in smectite clay minerals are leading to the development of new classes of selective heterogeneous catalysts. The selectivity of both metal-catalyzed and proton-catalyzed chemical conversions in clay intercalates can often be regulated by controlling surface chemical equilibria, interlamellar swelling, or reactant pair proximity in the interlayer regions. Also, the intercalation of polynuclear hydroxy metal cations and metal cluster cations in smectites affords new pillared clay catalysts with pore sizes that can be made larger than those of conventional zeolite catalysts.

1,456 citations

Journal ArticleDOI
TL;DR: Halloysite clay minerals are ubiquitous in soils and weathered rocks where they occur in a variety of particle shapes and hydration states as discussed by the authors and diversity also characterizes their chemical composition, cation exchange capacity and potassium selectivity.
Abstract: Halloysite clay minerals are ubiquitous in soils and weathered rocks where they occur in a variety of particle shapes and hydration states. Diversity also characterizes their chemical composition, cation exchange capacity and potassium selectivity. This review summarizes the extensive but scattered literature on halloysite, from its natural occurrence, through its crystal structure, chemical and morphological diversity, to its reactivity toward organic compounds, ions and salts, involving the various methods of differentiating halloysite from kaolinite. No unique test seems to be ideal to distinguish these 1:1 clay minerals, especially in soils. The occurrence of 2:1 phyllosilicate contaminants appears, so far, to provide the best explanation for the high charge and potassium selectivity of halloysite. Yet, hydration properties of the mineral probably play a major role in ion sorption. Clear trends seem to relate particle morphology and structural Fe. However, future work is required to understand the possible mechanisms linking chemical, morphological, hydration and charge properties of halloysite.

1,156 citations

Journal ArticleDOI
TL;DR: A comprehensive review of the most relevant studies of the adsorption of non-ionic surfactants and polymers onto both silica and clay is presented in this article, along with the effect of electrolytes, polymers, high pressure and high temperature on the flow behaviour of Na+-montmorillonite suspensions.

888 citations

Journal ArticleDOI
TL;DR: In this article, a layered protonic titanate of lepidocrocite-type was exfoliated on the action of an aqueous solution of tetrabutylammonium (hereafter TBA) hydroxide, resulting in a stable colloidal suspension.
Abstract: A layered protonic titanate of lepidocrocite-type, HxTi2-x/4□x/4O4·H2O (x ∼ 0.7; □, vacancy), has been exfoliated on the action of an aqueous solution of tetrabutylammonium (hereafter TBA) hydroxide, which resulted in a stable colloidal suspension. A colloidal aggregate centrifuged from the suspension was examined by an in situ X-ray diffraction technique under conditions where drying speed was controlled. The diffraction immediately after separation from the liquid phase was principally amorphous except for a series of sharp reflections detected in a small angle scattering region. On the basis of the line profile analysis, the latter diffraction feature was accounted for by the fundamental intersheet interference of a spacing >10 nm, which demonstrates the existence of a novel associated pair of the titanate nanosheets accommodating a large volume of water cluster between them. These XRD data provide persuasive evidence for delamination into single layers. Upon drying, the amorphous halo disappeared and ...

749 citations

Journal ArticleDOI
TL;DR: In this article, the role of magnetic enhancement and dilution in determining soil magnetic properties is investigated for a range of modern soil types, including those of the Chinese Loess Plateau, Tajikistan and the Czech Republic, and the relationship is completely opposite, with susceptibility minima associated with the most developed paleosols.

686 citations