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Sample records for clay minerals society

  1. Enchanted Clays: 44th Annual Meeting of the Clay Minerals Society (June 2007)

    Energy Technology Data Exchange (ETDEWEB)

    Randall T. Cygan

    2007-06-01

    “Enchanted Clays: 44th Annual Meeting of the Clay Minerals Society” was held in early June 2007 in beautiful and historic Santa Fe, New Mexico, USA. Santa Fe provided an idyllic location in the southwestern United States for the attendees to enjoy technical and social sessions while soaking up the diverse culture and wonderful climate of New Mexico—The Land of Enchantment. The meeting included a large and varied group of scientists, sharing knowledge and ideas, benefitting from technical interactions, and enjoying the wonderful historic and enchanted environs of Santa Fe. Including significant number of international scientists, the meeting was attended by approximately two hundred participants. The meeting included three days of technical sessions (oral and poster presentations), three days of field trips to clay and geological sites of northern New Mexico, and a full day workshop on the stabilization of carbon by clays. Details can be found at the meeting web site: www.sandia.gov/clay.

  2. Program and Abstracts for Clay Minerals Society 28th Annual Meeting

    Science.gov (United States)

    1991-01-01

    This volume contains abstracts that were accepted for presentation at the annual meeting. Some of the main topics covered include: (1) fundamental properties of minerals and methods of mineral analysis; (2) surface chemistry; (3) extraterrestrial clay minerals; (4) geothermometers and geochronometers; (5) smectite, vermiculite, illite, and related reactions; (6) soils and clays in environmental research; (7) kaolinite, halloysite, iron oxides, and mineral transformations; and (8) clays in lakes, basins, and reservoirs.

  3. Clay minerals in pollution control

    Energy Technology Data Exchange (ETDEWEB)

    Tateo, F. [Consiglio Nazionale delle Ricerche, Istituto di Ricerca sulle Argille, Tito Scalo, PZ (Italy)

    2000-07-01

    Clay minerals are fundamental constituents of life, not only as possible actors in the development of life on the Earth (Cairns-Smith and Hartman, 1986), but mainly because they are essential constituents of soils, the interface between the solid planet and the continental biosphere. Many, many authors have devoted themselves to the study of clays and clay minerals since the publication of the early modern studies by Grim (1953, 1962) and Millot (1964). In those years two very important associations were established in Europe (Association Internationale pour l'Etude des Argiles, AIPEA) and in the USA (Clay Mineral Society, CMS). The importance of these societies is to put together people that work in very different fields (agronomy, geology, geochemistry, industry, etc.), but with a common language (clays), very useful in scientific work. Currently excellent texts are being published, but introductory notes are also available on the web (Schroeder, 1998).

  4. Clay Mineral: Radiological Characterization

    Science.gov (United States)

    Cotomácio, J. G.; Silva, P. S. C.; Mazzilli, B. P.

    2008-08-01

    Since the early days, clays have been used for therapeutic purposes. Nowadays, most minerals applied as anti-inflammatory, pharmaceutics and cosmetic are the clay minerals that are used as the active ingredient or, as the excipient, in formulations. Although their large use, few information is available in literature on the content of the radionuclide concentrations of uranium and thorium natural series and 40K in these clay minerals. The objective of this work is to determine the concentrations of 238U, 232Th, 226Ra, 228Ra, 210Pb and 40K in commercial samples of clay minerals used for pharmaceutical or cosmetic purposes. Two kinds of clays samples were obtained in pharmacies, named green clay and white clay. Measurement for the determination of 238U and 232Th activity concentration was made by alpha spectrometry and gamma spectrometry was used for 226Ra, 228Ra, 210Pb and 40K determination. Some physical-chemical parameters were also determined as organic carbon and pH. The average activity concentration obtained was 906±340 Bq kg-1 for 40K, 40±9 Bq kg-1 for 226Ra, 75±9 Bq kg-1 for 228Ra, 197±38 Bq kg-1 for 210Pb, 51±26 Bq kg-1 for 238U and 55±24 Bq kg-1 for 232Th, considering both kinds of clay.

  5. Mineral resource of the Month: Clay

    Science.gov (United States)

    Virta, Robert L.

    2010-01-01

    Clays were one of the first mineral commodities used by people. Clay pottery has been found in archeological sites that are 12,000 years old, and clay figurines have been found in sites that are even older.

  6. Dehydration-induced luminescence in clay minerals

    Science.gov (United States)

    Coyne, L. M.; Lahav, N.; Lawless, J. G.

    1981-01-01

    Reports of triboluminescent phenomena in organic crystalline materials prompted a search for related processes in clay minerals. The reported extensive mechanical distortion produced on freezing and drying of montmorillonite was particularly interesting because of studies of condensation reactions in a wet/dry cycled reaction sequence. The discovery of an unusual luminescent process in several clay minerals is reported and its characteristics are described.

  7. Toxicological evaluation of clay minerals and derived nanocomposites: a review.

    Science.gov (United States)

    Maisanaba, Sara; Pichardo, Silvia; Puerto, María; Gutiérrez-Praena, Daniel; Cameán, Ana M; Jos, Angeles

    2015-04-01

    Clays and clay minerals are widely used in many facets of our society. This review addresses the main clays of each phyllosilicate groups, namely, kaolinite, montmorillonite (Mt) and sepiolite, placing special emphasis on Mt and kaolinite, which are the clays that are more frequently used in food packaging, one of the applications that are currently exhibiting higher development. The improvements in the composite materials obtained from clays and polymeric matrices are remarkable and well known, but the potential toxicological effects of unmodified or modified clay minerals and derived nanocomposites are currently being investigated with increased interest. In this sense, this work focused on a review of the published reports related to the analysis of the toxicological profile of commercial and novel modified clays and derived nanocomposites. An exhaustive review of the main in vitro and in vivo toxicological studies, antimicrobial activity assessments, and the human and environmental impacts of clays and derived nanocomposites was performed. From the analysis of the scientific literature different conclusions can be derived. Thus, in vitro studies suggest that clays in general induce cytotoxicity (with dependence on the clay, concentration, experimental system, etc.) with different underlying mechanisms such as necrosis/apoptosis, oxidative stress or genotoxicity. However, most of in vivo experiments performed in rodents showed no clear evidences of systemic toxicity even at doses of 5000mg/kg. Regarding to humans, pulmonary exposure is the most frequent, and although clays are usually mixed with other minerals, they have been reported to induce pneumoconiosis per se. Oral exposure is also common both intentionally and unintentionally. Although they do not show a high toxicity through this pathway, toxic effects could be induced due to the increased or reduced exposure to mineral elements. Finally, there are few studies about the effects of clay minerals on

  8. Mineral acquisition from clay by budongo forest chimpanzees

    NARCIS (Netherlands)

    Reynolds, Vernon; Lloyd, Andrew W.; English, Christopher J.; Lyons, Peter; Dodd, Howard; Hobaiter, Catherine; Newton-Fisher, Nicholas; Mullins, Caroline; Lamon, Noemie; Schel, Anne Marijke; Fallon, Brittany

    2015-01-01

    Chimpanzees of the Sonso community, Budongo Forest, Uganda were observed eating clay and drinking clay-water from waterholes. We show that clay, clay-rich water, and clay obtained with leaf sponges, provide a range of minerals in different concentrations. The presence of aluminium in the clay consum

  9. Uranyl adsorption at clay mineral surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Roesch, N. [Technische Univ. Muenchen (Germany). Fachgebiet Theoretische Chemie

    2016-11-01

    This first systematic survey of actinide adsorption at complex clay mineral surfaces, which provided new insights at the atomic level, is currently being extended to neptunyl NpO{sub 2}{sup +} and more complex minerals, like iron-substituted phyllosilicates. In this way we examine if the concepts developed so far can be applied more generally to support the interpretation of pertinent experiments. A further facet of these studies is to account also for the dynamic nature of the mineral/water interface by means of exemplary dynamic simulations.

  10. Mineral Acquisition from Clay by Budongo Forest Chimpanzees.

    Science.gov (United States)

    Reynolds, Vernon; Lloyd, Andrew W; English, Christopher J; Lyons, Peter; Dodd, Howard; Hobaiter, Catherine; Newton-Fisher, Nicholas; Mullins, Caroline; Lamon, Noemie; Schel, Anne Marijke; Fallon, Brittany

    2015-01-01

    Chimpanzees of the Sonso community, Budongo Forest, Uganda were observed eating clay and drinking clay-water from waterholes. We show that clay, clay-rich water, and clay obtained with leaf sponges, provide a range of minerals in different concentrations. The presence of aluminium in the clay consumed indicates that it takes the form of kaolinite. We discuss the contribution of clay geophagy to the mineral intake of the Sonso chimpanzees and show that clay eaten using leaf sponges is particularly rich in minerals. We show that termite mound soil, also regularly consumed, is rich in minerals. We discuss the frequency of clay and termite soil geophagy in the context of the disappearance from Budongo Forest of a formerly rich source of minerals, the decaying pith of Raphia farinifera palms.

  11. Clay mineral type effect on bacterial enteropathogen survival in soil.

    Science.gov (United States)

    Brennan, Fiona P; Moynihan, Emma; Griffiths, Bryan S; Hillier, Stephen; Owen, Jason; Pendlowski, Helen; Avery, Lisa M

    2014-01-15

    Enteropathogens released into the environment can represent a serious risk to public health. Soil clay content has long been known to have an important effect on enteropathogen survival in soil, generally enhancing survival. However, clay mineral composition in soils varies, and different clay minerals have specific physiochemical properties that would be expected to impact differentially on survival. This work investigated the effect of clay materials, with a predominance of a particular mineral type (montmorillonite, kaolinite, or illite), on the survival in soil microcosms over 96 days of Listeria monocytogenes, Salmonella Dublin, and Escherichia coli O157. Clay mineral addition was found to alter a number of physicochemical parameters in soil, including cation exchange capacity and surface area, and this was specific to the mineral type. Clay mineral addition enhanced enteropathogen survival in soil. The type of clay mineral was found to differentially affect enteropathogen survival and the effect was enteropathogen-specific.

  12. Ice nucleation efficiency of clay minerals in the immersion mode

    Directory of Open Access Journals (Sweden)

    V. Pinti

    2012-01-01

    Full Text Available Emulsion and bulk freezing experiments were performed to investigate immersion ice nucleation on clay minerals in pure water, using various kaolinites, montmorillonites, illites as well as natural dust from the Hoggar Mountains in the Saharan region. DSC (differential scanning calorimeter measurements were performed on the kaolinites KGa-1b and KGa-2 from the Clay Mineral Society and kaolinite from Sigma-Aldrich; the montmorillonites SWy-2 and STx-1b from the Clay Mineral Society and the acid treated montmorillonites KSF and K-10 from Sigma Aldrich; the illites NX and SE from Arginotec. The emulsion experiments provide information on the average freezing behaviour characterized by the average nucleation sites. These experiments revealed one to two distinct heterogeneous freezing peaks, which suggest the presence of a low number of qualitatively distinct average nucleation site classes. We refer to the peak at the lowest temperature as "standard peak" and to the one at higher temperatures as "special peak". Conversely, freezing in bulk samples is not initiated by the average nucleation sites, but by a very low number of "best sites". The kaolinites showed quite narrow standard peaks with onset temperatures 239 K < Tonstd < 242 K and best sites with averaged median freezing temperature Tmedbest = 257 K. Only the kaolinite from Sigma Aldrich featured a special peak with freezing onset at 248 K. The illites showed broad standard peaks with freezing onsets at 244 K < Tonstd < 246 K and best sites with averaged median freezing temperature Tmedbest = 262 K. Montmorillonites had standard peaks with onsets 238 K < Tonstd < 240 K and best sites with Tmedbest=257 K. SWy-2, M K10, and KSF featured special peaks with onsets at Tonspcl=247, 240, and 242 K

  13. Alteration of swelling clay minerals by acid activation

    NARCIS (Netherlands)

    Steudel, A.; Batenburg, L.F.; Fischer, H.R.; Weidler, P.G.; Emmerich, K.

    2009-01-01

    The bulk material of six dioctahedral and two trioctahedral swellable clay minerals was leached in H2SO4 and HCl at concentrations of 1.0, 5.0 and 10.0 M at 80 °C for several hours. Alteration of the clay mineral structures was dependent on the individual character of each mineral (chemical composit

  14. Optimization method for quantitative calculation of clay minerals in soil

    Indian Academy of Sciences (India)

    Libo Hao; Qiaoqiao Wei; Yuyan Zhao; Zilong Lu; Xinyun Zhao

    2015-04-01

    Determination of types and amounts for clay minerals in soil are important in environmental, agricultural, and geological investigations. Many reliable methods have been established to identify clay mineral types. However, no reliable method for quantitative analysis of clay minerals has been established so far. In this study, an attempt was made to propose an optimization method for the quantitative determination of clay minerals in soil based on bulk chemical composition data. The fundamental principles and processes of the calculation are elucidated. Some samples were used for reliability verification of the method and the results prove the simplicity and efficacy of the approach.

  15. Recent advances in clay mineral-containing nanocomposite hydrogels.

    Science.gov (United States)

    Zhao, Li Zhi; Zhou, Chun Hui; Wang, Jing; Tong, Dong Shen; Yu, Wei Hua; Wang, Hao

    2015-12-28

    Clay mineral-containing nanocomposite hydrogels have been proven to have exceptional composition, properties, and applications, and consequently have attracted a significant amount of research effort over the past few years. The objective of this paper is to summarize and evaluate scientific advances in clay mineral-containing nanocomposite hydrogels in terms of their specific preparation, formation mechanisms, properties, and applications, and to identify the prevailing challenges and future directions in the field. The state-of-the-art of existing technologies and insights into the exfoliation of layered clay minerals, in particular montmorillonite and LAPONITE®, are discussed first. The formation and structural characteristics of polymer/clay nanocomposite hydrogels made from in situ free radical polymerization, supramolecular assembly, and freezing-thawing cycles are then examined. Studies indicate that additional hydrogen bonding, electrostatic interactions, coordination bonds, hydrophobic interaction, and even covalent bonds could occur between the clay mineral nanoplatelets and polymer chains, thereby leading to the formation of unique three-dimensional networks. Accordingly, the hydrogels exhibit exceptional optical and mechanical properties, swelling-deswelling behavior, and stimuli-responsiveness, reflecting the remarkable effects of clay minerals. With the pivotal roles of clay minerals in clay mineral-containing nanocomposite hydrogels, the nanocomposite hydrogels possess great potential as superabsorbents, drug vehicles, tissue scaffolds, wound dressing, and biosensors. Future studies should lay emphasis on the formation mechanisms with in-depth insights into interfacial interactions, the tactical functionalization of clay minerals and polymers for desired properties, and expanding of their applications.

  16. Late Precambrian oxygenation; inception of the clay mineral factory.

    Science.gov (United States)

    Kennedy, Martin; Droser, Mary; Mayer, Lawrence M; Pevear, David; Mrofka, David

    2006-03-10

    An enigmatic stepwise increase in oxygen in the late Precambrian is widely considered a prerequisite for the expansion of animal life. Accumulation of oxygen requires organic matter burial in sediments, which is largely controlled by the sheltering or preservational effects of detrital clay minerals in modern marine continental margin depocenters. Here, we show mineralogical and geochemical evidence for an increase in clay mineral deposition in the Neoproterozoic that immediately predated the first metazoans. Today most clay minerals originate in biologically active soils, so initial expansion of a primitive land biota would greatly enhance production of pedogenic clay minerals (the "clay mineral factory"), leading to increased marine burial of organic carbon via mineral surface preservation.

  17. The systems containing clays and clay minerals from modified drug release: a review.

    Science.gov (United States)

    Rodrigues, Luís Alberto de Sousa; Figueiras, Ana; Veiga, Francisco; de Freitas, Rivelilson Mendes; Nunes, Lívio César Cunha; da Silva Filho, Edson Cavalcanti; da Silva Leite, Cleide Maria

    2013-03-01

    Clays are materials commonly used in the pharmaceutical industry, either as ingredients or as active ingredients. It was observed that when they are administered concurrently, they may interact with drugs reducing their absorption. Therefore, such interactions can be used to achieve technological and biopharmaceutical advantages, regarding the control of release. This review summarizes bibliographic (articles) and technological (patents) information on the use of systems containing clays and clay minerals in modified drug delivery. In this area, formulations such natural clay, commercial clay, synthetic clay, composites clay-polymers, nanocomposites clay-polymers, films and hidrogels composites clay-polymers are used to slow/extend or vectorize the release of drugs and consequently they increase their bioavailability. Finally, this review summarizes the fields of technology and biopharmaceutical applications, where clays are applied.

  18. The effect of clay minerals on diasterane/sterane ratios

    Science.gov (United States)

    van Kaam-Peters, Heidy M. E.; Köster, Jürgen; van der Gaast, Sjierk J.; Dekker, Marlèn; de Leeuw, Jan W.; Sinninghe Damsté, Jaap S.

    1998-09-01

    To examine the effect of clay minerals on diasterane/sterane ratios, the mineral compositions of three sample sets of sedimentary rocks displaying a wide range of diasterane/sterane ratios were analysed quantitatively. Diasterane/sterane ratios do not to correlate with clay content but depend on the amount of clay relative to the amount of organic matter (clay/TOC ratios). This correlation may explain the high diasterane/sterane ratios in crude oils and extracts derived from certain carbonate source rocks. Based on the concentrations of regular and rearranged steroids in the sample sets, it is proposed that diasterenes are partly reduced to diasteranes and partly degraded during diagenesis in a ratio largely determined by the availability of clay minerals. It is suggested that the hydrogen atoms required for reduction of the diasterenes originate from the water in the interlayers of clay minerals.

  19. The effect of clay minerals on diasterane/sterane ratios

    NARCIS (Netherlands)

    Sinninghe Damsté, J.S.; Kaam-Peters, H.M.E. van; Koster, J.; Gaast, S. J. van der; Dekker, M.H.A.; Leeuw, J.W. de

    1998-01-01

    To examine the effect of clay minerals on diasterane/sterane ratios, the mineral compositions of three sample sets of sedimentary rocks displaying a wide range of diasterane/sterane ratios were analysed quantitatively. Diasterane/sterane ratios do not to correlate with clay content but depend on the

  20. Impact-Induced Clay Mineral Formation and Distribution on Mars

    Science.gov (United States)

    Rivera-Valentin, E. G.; Craig, P. I.

    2015-01-01

    Clay minerals have been identified in the central peaks and ejecta blankets of impact craters on Mars. Several studies have suggested these clay minerals formed as a result of impact induced hydrothermalism either during Mars' Noachian era or more recently by the melting of subsurface ice. Examples of post-impact clay formation is found in several locations on Earth such as the Mjolnir and Woodleigh Impact Structures. Additionally, a recent study has suggested the clay minerals observed on Ceres are the result of impact-induced hydrothermal processes. Such processes may have occurred on Mars, possibly during the Noachian. Distinguishing between clay minerals formed preor post-impact can be accomplished by studying their IR spectra. In fact, showed that the IR spectra of clay minerals is greatly affected at longer wavelengths (i.e. mid-IR, 5-25 micron) by impact-induced shock deformation while the near-IR spectra (1.0-2.5 micron) remains relatively unchanged. This explains the discrepancy between NIR and MIR observations of clay minerals in martian impact craters noted. Thus, it allows us to determine whether a clay mineral formed from impact-induced hydrothermalism or were pre-existing and were altered by the impact. Here we study the role of impacts on the formation and distribution of clay minerals on Mars via a fully 3-D Monte Carlo cratering model, including impact- melt production using results from modern hydrocode simulations. We identify regions that are conducive to clay formation and the location of clay minerals post-bombardment.

  1. Characterization of clay minerals; Caracterizacion de minerales arcillosos

    Energy Technology Data Exchange (ETDEWEB)

    Diaz N, C.; Olguin, M.T.; Solache R, M.; Alarcon H, T.; Aguilar E, A. [Gerencia de Ciencias Basicas, Direccion de Investigacion Cientifica, Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    2002-07-01

    The natural clays are the more abundant minerals on the crust. They are used for making diverse industrial products. Due to the adsorption and ion exchange properties of these, a great interest for developing research directed toward the use of natural clays for the waste water treatment has been aroused. As part of such researches it is very important to carry out previously the characterization of the interest materials. In this work the results of the mineral and elemental chemical composition are presented as well as the morphological characteristics of clay minerals from different regions of the Mexican Republic. (Author)

  2. Quantification of clay minerals by combined EWA/XRD method

    Institute of Scientific and Technical Information of China (English)

    XU; Jianhong; (徐建红); XU; Jianhong; (徐建红); T.; R.; Astin; PAN; Mao; (潘懋)

    2001-01-01

    Illite has been considered the main constraint on permeability in the Morecambe Gas Field, East Irish Sea, UK. Previous research has emphasized the morphology rather than the amount of clay minerals. By applying a new method of clay mineral quantification, EWA/XRD, and applying statistical analysis methods, we are able to establish a quantitative model of illite distribution in the field. The result also leads to a better understanding of permeability distribution in reservoir sandstones.

  3. Identification of clay minerals in reservoir rocks by FTIR spectroscopy

    Science.gov (United States)

    Cong Khang, Vu; Korovkin, Mikhail V.; Ananyeva, Ludmila G.

    2016-09-01

    Clay minerals including kaolinite, montmorillonite and bentonite in oil and gas reservoir rocks are identified by absorption spectra obtained via Fourier Transform Infrared (FTIR) spectroscopy. Bands around 3695, 3666, 3650 and 3630 cm-1 and bands around 3620 and 3400 cm-1 are the most diagnostically reliable for kaolinite and montmorillonite, respectively; also absorption bands in the region of 1200...955 cm-1 are equally diagnostic for all the clay minerals studied.

  4. Clays and clay minerals in Bikaner: Sources, environment pollution and management

    Science.gov (United States)

    Gayatri, Sharma; Anu, Sharma

    2016-05-01

    Environmental pollution can also be caused by minerals which include natural as well as human activities. Rapid urbanization, consumerist life style, anthropogenic deeds are increasing environmental pollution day by day. Fluctuation in our ecosystem or polluted environment leads to many diseases and shows adverse effects on living organisms. The main aim of this paper is to highlight the environmental pollution from clays and clay minerals and their mitigation..

  5. Charge Properties and Clay Mineral Composition of Tianbao Mountains Soils

    Institute of Scientific and Technical Information of China (English)

    HEJI-ZHENG; LIXUE-YUAN; 等

    1992-01-01

    The clay mineral association,oxides of clay fraction and surface charge properties of 7 soils,which are developed from granite,located at different altitudesof the Tianbao Mountains were studied.Results indicate that with the increase in altitude,1) the weathering process and desilicification of soil clay minerals became weaker,whereas the leaching depotassication and the formation process of hydroxy-aluminum interlayer got stronger;2)the contents of amorphous and complex aluminum and iron,and the activity of aluminum and iron oxides for soil clay fraction increased;and 3) the amount of variable negarive charge,anion exchange capacity and the values of PZC and PZNC also increased.The activity of aluminum and iron oxides,the accumulation of aluminum,and surface charge characteristics and their relation to clay oxides of the vertical zone soils were observed and recorded.

  6. Fixation of Selenium by Clay Minerals and Iron Oxides

    DEFF Research Database (Denmark)

    Hamdy, A. A.; Nielsen, Gunnar Gissel

    1977-01-01

    In studying Se fixation, soil components capable of retaining Se were investigated. The importance of Fe hydrous oxides in the fixation of Se was established. The clay minerals common to soils, such as kaolinite, montmorillonite and vermiculite, all exhibited Se fixation, but greater fixation...... occurred with the 1:1 than the 2:1 clay type. Experiments with finely ground minerals showed that the pH of the systems greatly influenced the rate of fixation, reaching a maximum between pH 3 and 5 and decreasing rapidly as the pH increased. With the Fe2O3 system fixed Se was slightly reduced as the p......H was increased to over 8. The extractability of Se from the clay minerals indicated that 1:1 clay type minerals fix selenite more indissolubly than 2:1 clays and that selenite was adsorbed on the clays mainly by a surface exchange reaction. The major part of the selenite added to the Fe2O3 system was found...

  7. Microbial Impacts on Clay Mineral Transformation and Reactivity

    Science.gov (United States)

    Dong, H.; Jaisi, D.; Fredrickson, J.; Plymale, A.

    2006-05-01

    Clays and clay minerals are ubiquitous in soils, sedimentary rocks, and pelagic oozes. They play important roles in environmental processes such as nutrient cycling, plant growth, contaminant migration, organic matter maturation, and petroleum production. Iron is a major constituent in clay minerals, and its mobility and stability in different environmental processes is, in part, controlled by the oxidation state. Recent studies have shown that biological reduction of structural Fe(III) in clay minerals can change the physical and chemical properties of clay minerals, such as swelling, cation exchange and fixation capacity, specific surface area, color, and magnetic exchange interactions. As a result of biological reduction of Fe(III), clay minerals also undergo mineral transformations, such as dissolution of smectite and precipitation of illite, siderite and vivianite. These chemical, structural and mineralogical changes of clay minerals have a profound effect on clay mineral reactivity, such as their reactivity with organic and inorganic (i.e., heavy metals and radionuclides) contaminants. Our latest data show that biologically reduced nontronite (a smectite variety) is much more effective in reducing soluble and mobile Tc(VII) to Tc(IV) than unreduced nontronite. The reduced Tc(IV) is insoluble in groundwater and soil and thus is immobile. Biologically reduced nontronite can be prepared by microbially reducing Fe(III) in nontronite by Shewanella putrefaciens in the absence of oxygen. Approximately 30% of structurally Fe(III) can be reduced in this manner. Biogenic Fe(II) can then serve as an electron donor to reduce Tc(VII). Nearly all Fe(II) is available to reduce Tc(VII), with the rate of reduction (typically within weeks) possibly depending on the speciation of Fe(II) (surface sorbed Fe(II) vs. structural Fe(II)). Further investigations are underway to further assess the reversibility of Tc reduction upon exposure to oxygen and to elucidate Tc reduction

  8. Black Carbon, The Pyrogenic Clay Mineral?

    Science.gov (United States)

    Most soils contain significant amounts of black carbon, much of which is present as discrete particles admixed with the coarse clay fraction (0.2–2.0 µm e.s.d.) and can be physically separated from the more abundant diffuse biogenic humic materials. Recent evidence has shown that naturally occurring...

  9. The influence of clay minerals on acoustic properties of sandstones

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, Olav

    1997-12-31

    This thesis aims to provide better understanding of the relationship between the acoustic properties and the petrophysical/mineralogical properties in sand-prone rock. It emphasizes the influence of clay minerals. The author develops a method to deposit clay minerals/mineral aggregates in pore space of a rigid rock framework. Kaolinite aggregates were flushed into porous permeable Bentheimer sandstone to evaluate the effect of pore filling minerals on porosity, permeability and acoustic properties. The compressional velocity was hardly affected by the clay content and it was found that the effect of minor quantities of pore filling minerals may be acoustically modelled as an ideal suspension, where the pore fluid bulk modulus is modified by the bulk modulus of the clay minerals. The influence of clays on acoustic velocities in petroleum reservoir rocks was investigated through ultrasonic measurements of compressional- and shear-waves on core material from reservoir and non-reservoir units on the Norwegian Continental Shelf. The measured velocities decrease as the porosity increases, but are not strongly dependent on the clay content. The measured velocities are less dependent on the petrophysical and lithological properties than indicated by previous authors and published mathematical models, and stiffness reduction factors are introduced in two of the models to better match the data. Velocities are estimated along the wellbores based on non-sonic well logs and reflect well the actual sonic log well measurements. In some wells the compressional velocity cannot be modelled correctly by the models suggested. Very high compressional wave anisotropy was measured in the dry samples at atmospheric conditions. As the samples were saturated, the anisotropy was reduced to a maximum of about 30% and decreases further upon pressurization. Reservoir rocks retrieved from 2500 m are more stress dependent than those retrieved from less than 200 m depth. 168 refs., 117 figs., 24

  10. Crystallite size distribution of clay minerals from selected Serbian clay deposits

    Directory of Open Access Journals (Sweden)

    Simić Vladimir

    2006-01-01

    Full Text Available The BWA (Bertaut-Warren-Averbach technique for the measurement of the mean crystallite thickness and thickness distributions of phyllosilicates was applied to a set of kaolin and bentonite minerals. Six samples of kaolinitic clays, one sample of halloysite, and five bentonite samples from selected Serbian deposits were analyzed. These clays are of sedimentary volcano-sedimentary (diagenetic, and hydrothermal origin. Two different types of shape of thickness distribution were found - lognormal, typical for bentonite and halloysite, and polymodal, typical for kaolinite. The mean crystallite thickness (T BWA seams to be influenced by the genetic type of the clay sample.

  11. Effect of purity on adsorption capacities of a Mars-like clay mineral at different pressures

    Science.gov (United States)

    Jenkins, Traci; Mcdoniel, Bridgett; Bustin, Roberta; Allton, Judith H.

    1992-01-01

    There has been considerable interest in adsorption of carbon dioxide on Marslike clay minerals. Some estimates of the carbon dioxide reservoir capacity of the martian regolith were calculated from the amount of carbon dioxide adsorbed on the ironrich smectite nontronite under martian conditions. The adsorption capacity of pure nontronite could place upper limits on the regolith carbon dioxide reservoir, both at present martian atmospheric pressure and at the postulated higher pressures required to permit liquid water on the surface. Adsorption of carbon dioxide on a Clay Mineral Society standard containing nontronite was studied over a wide range of pressures in the absence of water. Similar experiments were conducted on the pure nontronite extracted from the natural sample. Heating curves were obtained to help characterize and determine the purity of the clay sample.

  12. First Direct Detection of Clay Minerals on Mars

    Science.gov (United States)

    Singer, R. B.; Owensby, P. D.; Clark, R. N.

    1985-01-01

    Magnesian clays or clay-type minerals were conclusively detected in the martian regolith. Near-IR spectral observations of Mars using the Mauna Kea 2.2-m telescope show weak but definite absorption bands near microns. The absorption band positions and widths match those produced by combined OH stretch and Mg-OH lattice modes and are diagnostic of minerals with structural OH such as clays and amphiboles. Likely candidate minerals include serpentine, talc, hectorite, and sponite. There is no spectral evidence for aluminous hydroxylated minerals. No distinct band occurs at 2.55 microns, as would be expected if carbonates were responsible for the 2.35 micron absorption. High-albedo regions such as Elysium and Utopia have the strongest bands near 2.35 microns, as would be expected for heavily weathered soils. Low-albedo regions such as Iapygia show weaker but distinct bands, consistent with moderate coatings, streaks, and splotches of bright weathered material. In all areas observed, the 2.35-micron absorption is at least three times weaker than would be expected if well-crystallized clay minerals made up the bulk of bright soils on Mars.

  13. Enhance decarboxylation reaction of carboxylic acids in clay minerals

    Energy Technology Data Exchange (ETDEWEB)

    Negron-Mendoza, A.; Ramos, S.; Albarran, G. [Instituto de Ciencias y Artes, Chiapas (Mexico). Escuela de Biologia

    1995-10-01

    Clay minerals are important constituents of the Earth`s crust. These minerals catalyze reactions in several ways: by energy transfer processes, redox reactions, stabilization of intermediates and by Broensted or Lewis acidity behavior. Important set of organic reactions can be improved in the precedence of clay minerals. Besides the properties of clays to catalyze chemical reactions, it is possible to enhance some of its reactions by using ionizing radiation. The phenomenon of radiation-induced catalysis may be connected with ionizing process in the solid and with the trapped non-equilibrium charge carriers. In this paper we are reporting the decarboxylation reaction of carboxylic acids catalyzed by clay and by irradiation of the system acid-clay. We studied the behaviour of several carboxylic acids and analyzed them by gas chromatography, X-ray and infrared spectroscopy. The results showed that decarboxylation of the target compound is the dominating pathway. The reaction is enhanced by gamma radiation in several orders of magnitude. (author).

  14. Radiation-induced defects in clay minerals: A review

    Energy Technology Data Exchange (ETDEWEB)

    Allard, Th., E-mail: thierry.allard@impmc.upmc.fr [IMPMC, UMR CNRS 7590, Universite Pierre et Marie Curie, Universite Denis Diderot, IRD, IPGP, Case 115, 4 Place Jussieu, 75005 Paris (France); Balan, E.; Calas, G.; Fourdrin, C.; Morichon, E.; Sorieul, S. [IMPMC, UMR CNRS 7590, Universite Pierre et Marie Curie, Universite Denis Diderot, IRD, IPGP, Case 115, 4 Place Jussieu, 75005 Paris (France)

    2012-04-15

    Extensive information has been collected on radiation effects on clay minerals over the last 35 years, providing a wealth of information on environmental and geological processes. The fields of applications include the reconstruction of past radioelement migrations, the dating of clay minerals or the evolution of the physico-chemical properties under irradiation. The investigation of several clay minerals, namely kaolinite, dickite, montmorillonite, illite and sudoite, by Electron Paramagnetic Resonance Spectroscopy has shown the presence of defects produced by natural or artificial radiations. These defects consist mostly of electron holes located on oxygen atoms of the structure. The various radiation-induced defects are differentiated through their nature and their thermal stability. Most of them are associated with a {pi} orbital on a Si-O bond. The most abundant defect in clay minerals is oriented perpendicular to the silicate layer. Thermal annealing indicates this defect in kaolinite (A-center) to be stable over geological periods at ambient temperature. Besides, electron or heavy ion irradiation easily leads to an amorphization in smectites, depending on the type of interlayer cation. The amorphization dose exhibits a bell-shaped variation as a function of temperature, with a decreasing part that indicates the influence of thermal dehydroxylation. Two main applications of the knowledge of radiation-induced defects in clay minerals are derived: (i) The use of defects as tracers of past radioactivity. In geological systems where the age of the clay can be constrained, ancient migrations of radioelements can be reconstructed in natural analogues of high level nuclear waste repositories. When the dose rate may be assumed constant over time, the paleodose is used to date clay populations, an approach applied to fault gouges or laterites of the Amazon basin. (ii) The influence of irradiation over physico-chemical properties of clay minerals. An environmental

  15. Interaction of oil components and clay minerals in reservoir sandstones

    Energy Technology Data Exchange (ETDEWEB)

    Changchun Pan; Linping Yu; Guoying Sheng; Jiamo Fu [Chinese Academy of Sciences, State Key Lab. of Organic Geochemistry, Wushan, Guangzhou (China); Jianhui Feng; Yuming Tian [Chinese Academy of Sciences, State Key Lab. of Organic Geochemistry, Wushan, Guangzhou (China); Zhongyuan Oil Field Co., Puyang, Henan (China); Xiaoping Luo [Zhongyuan Oil Field Co., Puyang, Henan (China)

    2005-04-15

    The free oil (first Soxhlet extract) and adsorbed oil (Soxhlet extract after the removal of minerals) obtained from the clay minerals in the <2 {mu}m size fraction as separated from eight hydrocarbon reservoir sandstone samples, and oil inclusions obtained from the grains of seven of these eight samples were studied via GC, GC-MS and elemental analyses. The free oil is dominated by saturated hydrocarbons (61.4-87.5%) with a low content of resins and asphaltenes (6.0-22.0% in total) while the adsorbed oil is dominated by resins and asphaltenes (84.8-98.5% in total) with a low content of saturated hydrocarbons (0.6-9.5%). The inclusion oil is similar to the adsorbed oil in gross composition, but contains relatively more saturated hydrocarbons (16.87-31.88%) and less resins and asphaltenes (62.30-78.01% in total) as compared to the latter. Although the amounts of both free and adsorbed oils per gram of clay minerals varies substantially, the residual organic carbon content in the clay minerals of the eight samples, after the free oil extraction, is in a narrow range between 0.537% and 1.614%. From the decrease of the percentage of the extractable to the total of this residual organic matter of the clay minerals with burial depth it can be inferred that polymerization of the adsorbed polar components occurs with the increase of the reservoir temperature. The terpane and sterane compositions indicate that the oil adsorbed onto the clay surfaces appears to be more representative of the initial oil charging the reservoir than do the oil inclusions. This phenomenon could possibly demonstrate that the first oil charge preferentially interacts with the clay minerals occurring in the pores and as coatings around the grains. Although the variation of biomarker parameters between the free and adsorbed oils could be ascribed to the compositional changes of oil charges during the filling process and/or the differential maturation behaviors of these two types of oils after oil

  16. [Occurrence relationship between iron minerals and clay minerals in net-like red soils: evidence from X-ray diffraction].

    Science.gov (United States)

    Yin, Ke; Hong, Han-Lie; Han, Weni; Ma, Yu-Bo; Li, Rong-Biao

    2013-04-01

    The high purity of clay minerals is a key factor to reconstruct the palaeoclimate in clay mineralogy, however, the existence of iron minerals (such as goethite and hematite) and organics lead to the intergrowth of clay minerals and other minerals, producing other mineral impurities in enriched clay minerals. Although the removal of organics in soil sediments has been fully investigated, the occurrence state of iron minerals remains controversial, hindering the preparation of high-purity clay minerals. Therefore, the occurrence relationship of iron minerals and clay minerals in Jiujiang net-like red soils of the middle to lower reaches of the Yangtze River was investigated using the sequential separation method, which provided some implications for the removal of iron minerals in soil sediments. The results indicated that goethite and hematite were mostly absorbed on the surface of hydroxy-interlayered smectite and illite in the form of films, and the rest were absorbed by kaolinite.

  17. Picloram and Aminopyralid Sorption to Soil and Clay Minerals

    Science.gov (United States)

    Aminopyralid sorption data are lacking, and these data are needed to predict off-target transport and plant available herbicide in soil solution. The objective of this research was to determine the sorption of picloram and aminopyralid to five soils and three clay minerals and determine if the pote...

  18. Main Clay Minerals in Soils of Fujian Province,China

    Institute of Scientific and Technical Information of China (English)

    WANGGUO; ZHANGWEIMING; 等

    1996-01-01

    The clay minerals of more than 200 soil samples collected from various sites of Fujian Province were studied by the X-ray diffraction method and transmission electron microscopy to study their distribution and evolution.Montmorillonite was found in coastal solonchak,paddy soils derived from marine deposit,lacustrine deposit and river deposit,and some lateritic red soil,red soil and yellow soil with a low weathering degree.Chlorite existed mainly in coastal solonchak and paddy soil developed from marine deposit.1.4nm intergradient mineral appeared frequently in yellow soil,red soil and lateritic red soil.The content of 1.4nm intergradient mineral increased with the decrease of weathering degree from lateritic red soil to red soil to yellow soil.Hydrous micas were more in coastal solonchak,paddy soils derived from marine deposit,lacustrine deposit and river deposit.and puple soil from purple shale than in other soils.Kaolinte was the most important clay mineral in the soils iun this province.The higher the soil weathering degree,the more the kaolinite existed.From yellow soil to red soil to lateritic red soil,kaolinite increased gradually,Kaolinite was the predominant clay mineral accompanied by few other minerals in typical lateritic red soil. Tubular halloysite was a widespread clay mineral in soils of Fujian Province with varying quantities.The soil derived from the paent rocks rich in feldspar contained more tubular halloysite.Spheroidal halloysite was found in a red soil and a paddy soil developed from olivine basalt gibbsite in the soils in this district was largely“primary gibbsite” which formed in the early weathering stage.Gibbsite decreased with the increase of weathering degree from yellow soil to red soil to lateritic red soil.Goethite also decreased in the same sequence while hematite increased.

  19. Reactivity of clay minerals with acids and alkalies

    Science.gov (United States)

    Carroll, D.; Starkey, H.C.

    1971-01-01

    One-g samples of a montmorillonite, a metabentonite, an illite, two kaolinites, and three halloysites were treated with 50 ml of hydrochloric acid (6??45 N, 1:1), acetic acid (4??5 N, 1:3), sodium hydroxide (2??8 N), sodium chloride solution (pH 6??10; Na = 35???; Cl = 21??5???), and natural sea water (pH 7??85; Na = 35??5???; Cl = 21??5???) for a 10-day period in stoppered plastic vials. The supernatant solutions were removed from the clay minerals and analyzed for SiO2, Al2O3, CaO, MgO, Na2O, and K2O. All the solutions removed some SiO2, Al2O3, and Fe2O3 from the samples, but the quantities were small. Sodium hydroxide attacked the kaolin group minerals more strongly than it did montmorillonite, metabentonite, or illite. Halloysite was more strongly attacked by hydrochloric acid than was any of the other experimental minerals. Hydrochloric acid removed iron oxide coatings from soil clay minerals, but acetic acid did not remove them completely. The samples most strongly attacked by HCl and NaOH were examined by X-ray diffraction. Acid treatment did not destroy the structure of the clays, but the halloysite structure was partially destroyed. Sodium hydroxide attacked the halloysite structure, as shown by chemical analysis and X-ray diffraction. These experiments show that treatment in dilute acids has no harmful effect in the preparation of clays for X-ray diffraction. Acetic acid is preferred to hydrochloric acid for this purpose. Hydrochloric acid cleans clay minerals by removing free iron oxide from the surface; acetic acid is less effective. ?? 1971.

  20. Sorption of tylosin on clay minerals.

    Science.gov (United States)

    Zhang, Qian; Yang, Chen; Huang, Weilin; Dang, Zhi; Shu, Xiaohua

    2013-11-01

    The equilibrium sorption of tylosin (TYL) on kaolinite and montmorillonite was measured at different solution pH using batch reactor systems. The results showed that all the sorption isotherms were nonlinear and that the nonlinearity decreased as the solution pH increased for a given clay. At a specific aqueous concentration, the single-point sorption distribution coefficient (KD) of TYL decreased rapidly as the solution pH increased. A speciation-dependent sorption model that accounted for the contributions of the cationic and neutral forms of TYL fit the data well, suggesting that the sorption may be dominated by both ion exchange and hydrophobic interactions. The isotherm data also fit well to a dual mode model that quantifies the contributions of a site-limiting Langmuir component (ion exchange) and a non-specific linear partitioning component (hydrophobic interactions). X-ray diffraction analyses revealed that the interlayers of montmorillonite were expanded due to the uptake of TYL. TYL molecules likely form a monolayer surface coverage.

  1. Mineral resources of Peru's ancient societies

    Science.gov (United States)

    Brooks, W.E.

    2003-01-01

    Northern Peru has an exceptionally rich archaeological heritage that includes metalwork, ceramics and textiles. The success of at least a half-dozen pre-Columbian societies dating back 3,000 years and subsequent Spanish colonization in the 1400s has rested on the effective use of northern Peru's abundant resources. In the summer of 2000, my son Matt and I learned about that connection firsthand by volunteering at the Santa Rita B archaeological site in the Chao Valley near Trujillo in northern Peru. Riding donkey-back through the Andes and talking with local people, we got our hands dirty in the rich archaeology and geology of the area. We were able to correlate mineral occurrences to their various roles in society - opening a window into the region's fascinating past. From construction to metallurgy, pre-Columbian societies flourished and advanced because of their understanding and use of the available mineral resources.

  2. Adsorption of diethyl phthalate ester to clay minerals.

    Science.gov (United States)

    Wu, Yanhua; Si, Youbin; Zhou, Dongmei; Gao, Juan

    2015-01-01

    Phthalate esters are a group of plasticizers, which have been widely detected in China's agricultural and industrial soils. In this study, batch adsorption experiments were conducted to investigate the environmental effects on the adsorption of diethyl phthalate ester (DEP) to clay minerals. The results showed that DEP adsorption isotherms were well fitted with the Freundlich model; the interlayer spacing of K(+) saturated montmorillonite (K-mont) was the most important adsorption area for DEP, and di-n-butyl ester (DnBP) was limited to intercalate into the interlayer of K-mont due to the bigger molecular size; there was no significant effect of pH and ionic strength on DEP adsorption to K-mont/Ca-mont, but to Na-mont clay. The adsorption to kaolinite was very limited. Data of X-ray diffraction and FTIR spectra further proved that DEP molecules could intercalate into K-/Ca-mont interlayer, and might interact with clay through H-bonding between carbonyl groups and clay adsorbed water. Coated humic acid on clay surface would enhance DEP adsorption at low concentration, but not at high concentration (eg. Ce>0.26 mM). The calculated adsorption enthalpy (ΔHobs) and adsorption isotherms at varied temperatures showed that DEP could be adsorbed easier as more adsorbed. This study implied that clay type, compound structure, exchangeable cation, soil organic matter and temperature played important roles in phthalate ester's transport in soil.

  3. Adsorption of Nucleic Acid Bases, Ribose, and Phosphate by Some Clay Minerals

    OpenAIRE

    Hideo Hashizume

    2015-01-01

    Besides having a large capacity for taking up organic molecules, clay minerals can catalyze a variety of organic reactions. Derived from rock weathering, clay minerals would have been abundant in the early Earth. As such, they might be expected to play a role in chemical evolution. The interactions of clay minerals with biopolymers, including RNA, have been the subject of many investigations. The behavior of RNA components at clay mineral surfaces needs to be assessed if we are to appreciate ...

  4. Reversibility of soil forming clay mineral reactions induced by plant - clay interactions

    Science.gov (United States)

    Barré, P.; Velde, B.

    2012-04-01

    Recent data based upon observations of field experiments and laboratory experiments suggest that changes in phyllosilicate mineralogy, as seen by X-ray diffraction analysis, which is induced by plant action can be reversed in relatively short periods of time. Changes from diagenetic or metamorphic mineral structures (illite and chlorite) to those found in soils (mixed layered minerals in the smectite, hydroxy-interlayer mineral and illites) observed in Delaware Bay salt marsh sediments in periods of tens of years and observed under different biologic (mycorhize) actions in coniferous forests in the soil environment can be found to be reversed under other natural conditions. Reversal of this process (chloritisation of smectitic minerals in soils) has been observed in natural situations over a period of just 14 years under sequoia gigantia. Formation of smectite minerals from illite (potassic mica-like minerals) has been observed to occur under intensive agriculture conditions over periods of 80 years or so under intensive zea mais production. Laboratory experiments using rye grass show that this same process can be accomplished to a somewhat lesser extent after one growing season. However experiments using alfalfa for 30 year growing periods show that much of the illite content of a soil can be reconstituted or even increased. Observations on experiments using zea mais under various fertilizer and mycorhize treatments indicate that within a single growing season potassium can be extracted from the clay (illite layers) but at the end of the season the potassium can be restored to the clay structures and more replaced that extracted. Hence it is clear that the change in clay mineralogy normally considered to be irreversible, illite to smectite or chlorite to smectite observed in soils, is a reversible process where plant systems control the soil chemistry and the soil mineralogy. The changes in clay mineralogy concern mostly the chemical composition of the interlayer

  5. Deposition kinetics of MS2 bacteriophages on clay mineral surfaces.

    Science.gov (United States)

    Tong, Meiping; Shen, Yun; Yang, Haiyan; Kim, Hyunjung

    2012-04-01

    The deposition of bacteriophage MS2 on bare and clay-coated silica surfaces was examined in both monovalent (NaCl) and divalent (CaCl(2) and MgCl(2)) solutions under a wide range of environmentally relevant ionic strength and pH conditions by utilizing a quartz crystal microbalance with dissipation (QCM-D). Two types of clay, bentonite and kaolinite, were concerned in this study. To better understand MS2 deposition mechanisms, QCM-D data were complemented by zeta potentials measurements and Derjaguin-Landau-Verwey-Overbeek (DLVO) interaction forces calculation. In both monovalent and divalent solutions, deposition efficiencies of MS2 increased with increasing ionic strength both on bare and clay-coated surfaces, which agreed with the trends of interaction forces between MS2 and solid surface and thus was consistent with DLVO theory. The presence of divalent ions (Ca(2+) and Mg(2+)) in solutions greatly increased virus deposition on both silica and clay deposited surfaces. Coating silica surfaces with clay minerals, either kaolinite or bentonite, could significantly increase MS2 deposition.

  6. Enhanced coal and mineral flotation by selective clay agglomeration

    Energy Technology Data Exchange (ETDEWEB)

    Tao, D.; Chen, G.L.; Fan, M.M.; Zhou, X.H.; Zhao, C.; Aron, M.; Wright, J. [University of Kentucky, Lexington, KY (United States)

    2006-07-01

    The purpose is to evaluate the performance of clay binding agents for enhancing coal and mineral flotation. Mechanical and column flotation tests were conducted on coal and potash samples. Several process parameters were examined, e.g. impeller rotation speed, binder dosage, slurry solids content, and collector dosage. The results show that the Georgia-Pacific reagents improved flotation efficiency under some process conditions, especially at higher solids percentage and higher impeller rotation speed. 26 refs., 9 figs., 3 tabs.

  7. Transformation of anthracene on various cation-modified clay minerals.

    Science.gov (United States)

    Li, Li; Jia, Hanzhong; Li, Xiyou; Wang, Chuanyi

    2015-01-01

    In this study, anthracene was employed as a probe to explore the potential catalytic effect of clay minerals in soil environment. Clay minerals saturated with various exchangeable cations were tested. The rate of anthracene transformation follows the order: Fe-smectite > Cu-smectite > Al-smectite ≈ Ca-smectite ≈ Mg-smectite ≈ Na-smectite. This suggests that transition-metal ions such as Fe(III) play an important role in anthracene transformation. Among Fe(III)-saturated clays, Fe(III)-smectite exhibits the highest catalytic activity followed by Fe(III)-illite, Fe(III)-pyrophyllite, and Fe(III)-kaolinite, which is in agreement with the interlayer Fe(III) content. Moreover, effects by two common environmental factors, pH and relative humidity (RH), were evaluated. With an increase in pH or RH, the rate of anthracene transformation decreases rapidly at first and then is leveled off. GC-MS analysis identifies that the final product of anthracene transformation is 9,10-anthraquinone, a more bioavailable molecule compared to anthracene. The transformation process mainly involves cation-π bonding, electron transfer leading to cation radical, and further oxidation by chemisorbed O2. The present work provides valuable insights into the abiotic transformation and the fate of PAHs in the soil environment and the development of contaminated land remediation technologies.

  8. Adsorption of nucleic Acid bases, ribose, and phosphate by some clay minerals.

    Science.gov (United States)

    Hashizume, Hideo

    2015-01-01

    Besides having a large capacity for taking up organic molecules, clay minerals can catalyze a variety of organic reactions. Derived from rock weathering, clay minerals would have been abundant in the early Earth. As such, they might be expected to play a role in chemical evolution. The interactions of clay minerals with biopolymers, including RNA, have been the subject of many investigations. The behavior of RNA components at clay mineral surfaces needs to be assessed if we are to appreciate how clays might catalyze the formation of nucleosides, nucleotides and polynucleotides in the "RNA world". The adsorption of purines, pyrimidines and nucleosides from aqueous solution to clay minerals is affected by suspension pH. With montmorillonite, adsorption is also influenced by the nature of the exchangeable cations. Here, we review the interactions of some clay minerals with RNA components.

  9. Adsorption of Nucleic Acid Bases, Ribose, and Phosphate by Some Clay Minerals

    Directory of Open Access Journals (Sweden)

    Hideo Hashizume

    2015-02-01

    Full Text Available Besides having a large capacity for taking up organic molecules, clay minerals can catalyze a variety of organic reactions. Derived from rock weathering, clay minerals would have been abundant in the early Earth. As such, they might be expected to play a role in chemical evolution. The interactions of clay minerals with biopolymers, including RNA, have been the subject of many investigations. The behavior of RNA components at clay mineral surfaces needs to be assessed if we are to appreciate how clays might catalyze the formation of nucleosides, nucleotides and polynucleotides in the “RNA world”. The adsorption of purines, pyrimidines and nucleosides from aqueous solution to clay minerals is affected by suspension pH. With montmorillonite, adsorption is also influenced by the nature of the exchangeable cations. Here, we review the interactions of some clay minerals with RNA components.

  10. Clays and Clay Minerals and their environmental application in Food Technology

    Science.gov (United States)

    del Hoyo Martínez, Carmen; Cuéllar Antequera, Jorge; Sánchez Escribano, Vicente; Solange Lozano García, Marina; Cutillas Díez, Raul

    2013-04-01

    The clay materials have led to numerous applications in the field of public health (del Hoyo, 2007; Volzone, 2007) having been demonstrated its effectiveness as adsorbents of all contaminants. Some biodegradable materials are used for for adsorption of chemical contaminants: lignins (Valderrabano et al., 2008) and also clays and clay minerals, whose colloidal properties, ease of generating structural changes, abundance in nature, and low cost make them very suitable for this kind of applications. Among the strategies used at present to preserve the quality of the water and this way to diminish the environmental risk that supposes the chemical pollution, stands out the use of adsorbents of under cost, already they are natural or modified, to immobilize these compounds and to avoid the pollution of the water with the consequent reduction of environmental and economic costs Thanks to the development of the science and the technology of the nourishment in the last 50 years, there have revealed itself several new substances that can fulfill beneficial functions in the food, and these substances, named food additives, are today within reach of all. The food additives recover a very important role in the complex nourishing supply. The additives fulfill several useful functions in the food, which often we give for sat. Nevertheless the widespread use of food additives in the food production also influences the public health. The food industries, which are very important for the economy, spill residues proved from its activity that they have to be controlled to evaluate the environmental impact and to offer the necessary information about the quantitative evaluation of the chemical risk of the use of food additives for the public health. We have studied the adsorption of several contaminants by natural or modified clays, searching their interaction mechanisms and the possible recycling of these materials for environmental purposes and prevention of the health. References

  11. Iron(III)-bearing clay minerals enhance bioreduction of nitrobenzene by Shewanella putrefaciens CN32.

    Science.gov (United States)

    Luan, Fubo; Liu, Yan; Griffin, Aron M; Gorski, Christopher A; Burgos, William D

    2015-02-01

    Iron-bearing clay minerals are ubiquitous in the environment, and the clay-Fe(II)/Fe(III) redox couple plays important roles in abiotic reduction of several classes of environmental contaminants. We investigated the role of Fe-bearing clay minerals on the bioreduction of nitrobenzene. In experiments with Shewanella putrefaciens CN32 and excess electron donor, we found that the Fe-bearing clay minerals montmorillonite SWy-2 and nontronite NAu-2 enhanced nitrobenzene bioreduction. On short time scales (clay minerals became increasingly important. We found that chemically reduced (dithionite) iron-bearing clay minerals reduced nitrobenzene more rapidly than biologically reduced iron-bearing clay minerals despite the minerals having similar structural Fe(II) concentrations. We also found that chemically reduced NAu-2 reduced nitrobenzene faster as compared to chemically reduced SWy-2. The different reactivity of SWy-2 versus NAu-2 toward nitrobenzene was caused by different forms of structural clay-Fe(II) in the clay minerals and different reduction potentials (Eh) of the clay minerals. Because most contaminated aquifers become reduced via biological activity, the reactivity of biogenic clay-Fe(II) toward reducible contaminants is particularly important.

  12. Ice nucleation efficiency of clay minerals in the immersion mode

    Directory of Open Access Journals (Sweden)

    V. Pinti

    2012-07-01

    Full Text Available Emulsion and bulk freezing experiments were performed to investigate immersion ice nucleation on clay minerals in pure water, using various kaolinites, montmorillonites, illites as well as natural dust from the Hoggar Mountains in the Saharan region. Differential scanning calorimeter measurements were performed on three different kaolinites (KGa-1b, KGa-2 and K-SA, two illites (Illite NX and Illite SE and four natural and acid-treated montmorillonites (SWy-2, STx-1b, KSF and K-10. The emulsion experiments provide information on the average freezing behaviour characterized by the average nucleation sites. These experiments revealed one to sometimes two distinct heterogeneous freezing peaks, which suggest the presence of a low number of qualitatively distinct average nucleation site classes. We refer to the peak at the lowest temperature as "standard peak" and to the one occurring in only some clay mineral types at higher temperatures as "special peak". Conversely, freezing in bulk samples is not initiated by the average nucleation sites, but by a very low number of "best sites". The kaolinites and montmorillonites showed quite narrow standard peaks with onset temperatures 238 K<Tonstd<242 K and best sites with averaged median freezing temperature Tmedbest=257 K, but only some featuring a special peak (i.e. KSF, K-10, K-SA and SWy-2 with freezing onsets in the range 240–248 K. The illites showed broad standard peaks with freezing onsets at 244 K Tonstd<246 K and best sites with averaged median freezing temperature Tmedbest=262 K. The large difference between freezing temperatures of standard and best sites shows that characterizing ice nucleation efficiencies of dust particles on the basis of freezing onset temperatures from bulk experiments, as has been done in some atmospheric studies, is not appropriate. Our investigations

  13. Harnessing Water and Resources from Clay Minerals on Mars and Planetary Bodies

    Science.gov (United States)

    Bishop, J. L.

    2017-02-01

    Clay minerals provide a source of water, metals, and cations that can be harvested to provide resources for human exploration on Mars, asteroids, etc. Planning how to access these resources from clays could be a vital component of human exploration.

  14. Geothermal alteration of clay minerals and shales: diagenesis

    Energy Technology Data Exchange (ETDEWEB)

    Weaver, C.E.

    1979-07-01

    The objective of this report is to perform a critical review of the data on the mineral and chemical alterations that occur during diagenesis and low-grade metamorphism of shale and other clay-rich rocks - conditions similar to those expected from emplacement of heat-producing radioactive waste in a geologic repository. The conclusions drawn in this document are that the following type of alterations could occur: smectite alteration, ion mobilization, illitic shales, kaolinite reactions, chlorite reactions, organic reactions, paleotemperatures, low temperature shales, high temperature shales, and phase equilibrium changes.

  15. Separation of Clay Minerals from Host Sediments Using Cation Exchange Resins

    Institute of Scientific and Technical Information of China (English)

    I.S. Ismael; H.M. Baioumy

    2003-01-01

    Classic physical and chemical treatments applied to separating clay minerals from the host sediments are often difficult or aggressive for clay minerals. A technique using cation exchange resins (amberlite IRC-50H and amberlite IR-120) is used to separate clay minerals from the host sediments. The technique is based on the exchange of cations in the minerals that may be associated clay minerals in sediments,such as Ca and Mg from dolomite; Ca from calcite,gypsum and francolite with cations carried by resin radicals. The associated minerals such as gypsum,calcite,dolomite and francolite are removed in descending order. Separation of clay minerals using cation exchange resins is less aggressive than that by other classic treatments.The efficiency of amberlite IRC-50H in the removal of associated minerals is greater than that of amberlite IR-120.

  16. Clay minerals in the Meuse - Haute Marne underground laboratory (France): Possible influence of organic matter on clay mineral evolution.

    OpenAIRE

    Claret, Francis; Sakharov, Boris.A.; Drits, Victor A.; Velde, Bruce; Meunier, Alain; Griffault, Lise; Lanson, Bruno

    2004-01-01

    A clay-rich Callovo-Oxfordian sedimentary formation was selected in the eastern Paris Basin (MHM site) to host an underground laboratory dedicated to the assessment of nuclear waste disposal feasibility in deep geological formations. As described initially, this formation shows a mineralogical transition from an illite-smectite (I-S) mixed-layered mineral (MLM), which is essentially smectitic and randomly interstratified (R=0) in the top part of the series to a more illitic, ordered (R≥1) I-S...

  17. The formation of goethite and hydrated clay minerals on Mars

    Science.gov (United States)

    Huguenin, R. L.

    1974-01-01

    Laboratory studies reported by Huguenin (1973) on the kinetics and mechanism of the photostimulated oxidation of magnetic and preliminary laboratory data on the weathering of silicates, reported herein, are applied to Mars. Basalts in the Martian dark areas are predicted to alter to hydrated Fe(2 plus or minus) depleted clay minerals, minor goethite, and minor to trace amounts of transition metal oxides such as TiO2, MnO2, and Cr2O3 at a rate of 10 to the minus 1.5 plus or minus 1.5 micron/yr. Some Ca-Mg carbonates are also expected to be formed. The clay minerals are predicted to be more silica-rich than the silicate source material, SiO2 contents of 60% or higher being expected, and strongly depleted in Fe(2+). The oxygen, OH, and H2O contents of the bulk weathering product are predicted to be significantly greater than those of the dark-area source materials, whereas the relative bulk metal abundances should be the same.

  18. A Preliminary Study on Identification of Clay Minerals in Soils with Reference to Reflectance Spectra

    Institute of Scientific and Technical Information of China (English)

    XUBIN-BIN; LIDE-CHENG; 等

    1995-01-01

    The characteristics of the reflectance spectra of clay minerals and their influences on the reflectance spectra of soils are dealt with in the paper.The results showed that dominant clay minerals in soils could be distinguished in light of the spectral -form parameters of the reflectance spectra of soils,thus making it possible to develop a quick method to determine clay minerals by means of reflectance spectra of soils in the lab.and providing a theoretic basis for remote sensing of clay minerals in soils with a high resolution imaging spectrometer.

  19. Assessing the redox properties of iron-bearing clay minerals using homogeneous electrocatalysis

    Energy Technology Data Exchange (ETDEWEB)

    Gorski, Christopher A., E-mail: Christopher.gorski@eawag.ch [Environmental Chemistry, Eawag, Swiss Federal Institute of Aquatic Science and Technology, Uberlandstrasse 133, P.O. Box 611, 8600 Duebendorf (Switzerland); Sander, Michael; Aeschbacher, Michael [Institute of Biogeochemistry and Pollutant Dynamics (IBP), ETH Zurich, Universitaetstrasse 16, 8092 Zuerich (Switzerland); Hofstetter, Thomas B. [Environmental Chemistry, Eawag, Swiss Federal Institute of Aquatic Science and Technology, Uberlandstrasse 133, P.O. Box 611, 8600 Duebendorf (Switzerland)] [Institute of Biogeochemistry and Pollutant Dynamics (IBP), ETH Zurich, Universitaetstrasse 16, 8092 Zuerich (Switzerland)

    2011-06-15

    Iron-bearing clay minerals are ubiquitous in the environment and have been shown to play important roles in several biogeochemical processes. Previous efforts to characterize the Fe{sup 2+}-Fe{sup 3+} redox couple in clay minerals using electrochemical techniques have been limited by experimental difficulties due to inadequate reactivity between clay minerals and electrodes. The current work overcomes this limitation by utilizing organic electron transfer mediators that rapidly transfer electrons with both the Fe-bearing clay minerals and electrodes. Here, an Fe-rich source clay mineral (ferruginous smectite, SWa-1) is examined with respect to what fraction of structural Fe participates in oxidation/reduction reactions and the relationship between bulk Fe{sup 2+}/Fe{sup 3+} ratios to the reduction potential (E{sub h}).

  20. Clay Minerals in Mawrth Vallis Region of Mars

    Science.gov (United States)

    2008-01-01

    This map showing the location of some clay minerals in of a portion of the Mawrth Vallis region of Mars covers an area about 10 kilometers (6.2 mile) wide. The map is draped over a topographical model that exaggerates the vertical dimension tenfold. The mineral mapping information comes from an image taken on Sept. 21, 2007, by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM). Iron-magnesium phyllosilicate is shown in red. Aluminum phyllosyllicate is shown in blue. Hydrated silica and a ferrous iron phase are shown in yellow/green. The topographical information comes from the Mars Orbiter Laser Altimeter instrument on NASA's Mars Global Surveyor orbiter. Mawrth Vallis is an outflow channel centered near 24.7 degrees north latitude, 339.5 degrees east longitude, in northern highlands of Mars. CRISM is one of six science instruments on the Mars Reconnaissance Orbiter. Led by The Johns Hopkins University Applied Physics Laboratory, Laurel, Md., the CRISM team includes expertise from universities, government agencies and small businesses in the United States and abroad. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, built the orbiter.

  1. Bioremediation of PAHs and VOCs: Advances in clay mineral-microbial interaction.

    Science.gov (United States)

    Biswas, Bhabananda; Sarkar, Binoy; Rusmin, Ruhaida; Naidu, Ravi

    2015-12-01

    Bioremediation is an effective strategy for cleaning up organic contaminants, such as polycyclic aromatic hydrocarbons (PAHs) and volatile organic compounds (VOCs). Advanced bioremediation implies that biotic agents are more efficient in degrading the contaminants completely. Bioremediation by microbial degradation is often employed and to make this process efficient, natural and cost-effective materials can serve as supportive matrices. Clay/modified clay minerals are effective adsorbents of PAHs/VOCs, and readily available substrate and habitat for microorganisms in the natural soil and sediment. However, the mechanism underpinning clay-mediated biodegradation of organic compounds is often unclear, and this requires critical investigation. This review describes the role of clay/modified clay minerals in hydrocarbon bioremediation through interaction with microbial agents in specific scenarios. The vision is on a faster, more efficient and cost-effective bioremediation technique using clay-based products. This review also proposes future research directions in the field of clay modulated microbial degradation of hydrocarbons.

  2. Catalysis of aluminosilicate clay minerals to the formation of the transitional zone gas

    Institute of Scientific and Technical Information of China (English)

    雷怀彦; 师育新; 关平; 房玄

    1997-01-01

    It has been shown that the major clay minerals of the biothermocatalytic transitional zone source rock are montmorillonite, illite/montmorillonite (I/M) interlayer mineral, illite, kaolinite and chlorite. Within the depth of the transitional zone, montmorillonite could convert to the I/M ordered interlayer mineral via the I/M disordered one, i.e. in the intercrystalline layer of montmorillonite, Al3+ replaces Si4+ abundantly, resulting in a surface charge imbalance and the occurrence of a surface acidity. By means of the pyridine analytic method, the surface acidity of these aluminosilicate clay minerals is measured. The catalysis of aluminosilicate clay minerals, such as montmorillonite, illite and kaolinite to the thermo-degraded gas formation of the transitional zone is simulated in the differential thermal analysis-gas chromatography system and the alcohol dehydration catalyzed by clay minerals is employed to discuss this catalytic mechanism. Experiments have shown that montmorillonite is the major

  3. Sm-Nd dating of Fig Tree clay minerals of the Barberton greenstone belt, South Africa

    Science.gov (United States)

    Toulkeridis, T.; Goldstein, S. L.; Clauer, N.; Kroner, A.; Lowe, D. R.

    1994-01-01

    Sm-Nd isotopic data from carbonate-derived clay minerals of the 3.22-3.25 Ga Fig Tree Group, Barberton greenstone belt, South Africa, form a linear array corresponding to an age of 3102 +/- 64 Ma, making these minerals the oldest dated clays on Earth. The obtained age is 120-160 m.y. younger than the depositional age determined by zircon geochronology. Nd model ages for the clays range from approximately 3.39 to 3.44 Ga and almost cover the age variation of the Barberton greenstone belt rocks, consistent with independent evidence that the clay minerals are derived from material of the belt. The combined isotopic and mineralogical data provide evidence for a cryptic thermal overprint in the sediments of the belt. However, the highest temperature reached by the samples since the time of clay-mineral formation was <300 degrees C, lower than virtually any known early Archean supracrustal sequence.

  4. Distribution of Clay Minerals in Light Coal Fractions and the Thermal Reaction Products of These Clay Minerals during Combustion in a Drop Tube Furnace

    Directory of Open Access Journals (Sweden)

    Sida Tian

    2016-06-01

    Full Text Available To estimate the contribution of clay minerals in light coal fractions to ash deposition in furnaces, we investigated their distribution and thermal reaction products. The light fractions of two Chinese coals were prepared using a 1.5 g·cm−3 ZnCl2 solution as a density separation medium and were burned in a drop-tube furnace (DTF. The mineral matter in each of the light coal fractions was compared to that of the relevant raw coal. The DTF ash from light coal fractions was analysed using hydrochloric acid separation. The acid-soluble aluminium fractions of DTF ash samples were used to determine changes in the amorphous aluminosilicate products with increasing combustion temperature. The results show that the clay mineral contents in the mineral matter of both light coal fractions were higher than those in the respective raw coals. For the coal with a high ash melting point, clay minerals in the light coal fraction thermally transformed more dehydroxylation products compared with those in the raw coal, possibly contributing to solid-state reactions of ash particles. For the coal with a low ash melting point, clay minerals in the light coal fraction produced more easily-slagging material compared with those in the raw coal, playing an important role in the occurrence of slagging. Additionally, ferrous oxide often produces low-melting substances in coal ash. Due to the similarities of zinc oxide and ferrous oxide in silicate reactions, we also investigated the interactions of clay minerals in light coal fractions with zinc oxide introduced by a zinc chloride solution. The extraneous zinc oxide could react, to a small extent, with clay minerals in the coal during DTF combustion.

  5. MAX--An Interactive Computer Program for Teaching Identification of Clay Minerals by X-ray Diffraction.

    Science.gov (United States)

    Kohut, Connie K.; And Others

    1993-01-01

    Discusses MAX, an interactive computer program for teaching identification of clay minerals based on standard x-ray diffraction characteristics. The program provides tutorial-type exercises for identification of 16 clay standards, self-evaluation exercises, diffractograms of 28 soil clay minerals, and identification of nonclay minerals. (MDH)

  6. Thermal magnetic behaviour of Al-substituted haematite mixed with clay minerals and its geological significance

    Science.gov (United States)

    Jiang, Zhaoxia; Liu, Qingsong; Zhao, Xiangyu; Jin, Chunsheng; Liu, Caicai; Li, Shihu

    2015-01-01

    Clay minerals and Al-substituted haematite (Al-hm) usually coexist in soils and sediments. However, effects of clay minerals on Al-hm during thermal magnetic measurements in argon environment have not been well studied. In order to quantify such effects, a series of Al-hm samples were synthesized, and were then mixed with clay minerals (illite, chlorite, kaolinite and Ca-montmorillonite). The temperature dependence of magnetic susceptibility curves in an argon environment showed that Al-substituted magnetite was produced during the thermal treatment via the reduction of Al-hm by the clay mineral, which leads to a significant magnetic enhancement of the thermal products. In addition, the reductive capacity varies among different types of clay minerals, that is, illite > chlorite > kaolinite > Ca-montmorillonite. Furthermore, the iron content in the clay minerals and Al content of Al-hm are two predominant factors controlling the reduced haematite content. The iron is released from the clay minerals and provides the reducing agent, while Al decreases the crystallinity of haematite and thus facilitates the chemical reaction. Therefore, the thermal magnetic measurements can be used to quantify the Al content of Al-hm in natural samples. Our study provides significant information for palaeomagnetism and environmental magnetism studies, such as thermal magnetic analysis and palaeomagnetic intensity reconstruction using ancient pottery and kilns.

  7. Surveying Clay Mineral Diversity in the Murray Formation, Gale Crater, Mars

    Science.gov (United States)

    Bristow, T. F.; Blake, D. F.; Vaniman, D. T.; Chipera, S. J.; Rampe, E. B.; Grotzinger, J. P.; McAdam, A. C.; Ming, D. W.; Morrison, S. M.; Yen, A. S.; Morris, R. V.; Des Marais, D. J.

    2017-01-01

    One of the primary science goals of Mars Science Laboratory (MSL) is to investigate layered clay mineral-bearing deposits outcropping in the lower NW slopes of Aeolis Mons (Mt. Sharp) detected from orbit. Martian clay mineral-bearing layered rocks are of particular interest because they are potential markers of sedimentary deposits formed in habitable aqueous environments. The CheMin X-ray diffraction (XRD) instrument aboard MSL has documented clay minerals in various drill samples during its traverse of Gale Crater's floor and ascent of Mt. Sharp. Previously, the high concentrations of clay minerals (approximately 20 wt.%) detected in drill powders of mudstone (Sheepbed member) at Yellowknife Bay (YKB) allowed their detailed characterization. Drill powders recovered from lacustrine mudstones of the Sheepbed member at YKB contain smectite clay minerals. Based on the position of 02l reflections in XRD patterns, which serve as an indicator of octahedral occupancy, the smectites are Fe-bearing, trioctahedral species analogous to ferrian saponites from terrestrial deposits. The smectites are thought to have been formed through a process of isochemical aqueous alteration of detrital olivine close to the time of sediment deposition under anoxic to poorly oxidizing conditions. The clay minerals are key indicators that the lake waters were benign and habitable at the time. Clay minerals were detected at other locations during MSL's traverse, including samples from the Pahrump Hills, but lower abundances and overlapping peaks from crystalline phases in XRD patterns hamper in-depth analysis.

  8. Transport and selective uptake of radium into natural clay minerals

    Science.gov (United States)

    Hidaka, Hiroshi; Horie, Kenji; Gauthier-Lafaye, Françoise

    2007-12-01

    Understanding of the environmental behavior of Ra is important from the viewpoint of the long-termed repository safety of radioactive waste, but investigation of Ra behavior in natural environment is difficult to detect. We found isotopic evidence of Ra transportation and its selective uptake into clay minerals from Pb isotopic analyses. Illite grains found in calcite veins included in sandstone near the Oklo uranium deposit, Republic of Gabon, show extremely low 207Pb/ 206Pb (˜ 0.0158) isotopic ratios. Although the Pb isotopic ratios of calcite and quartz coexisting with illite indicate the formation age of each component, those of illite do not. In addition, illite grains having low 207Pb/ 206Pb isotopic ratios contain a strongly large amount of Ba (1230 to 6010 ppm) in contrast with low contents of Ba in calcite and quartz (< 0.26 ppm). Considering the chemical similarity between Ba and Ra, the 207Pb/ 206Pb isotopic data suggest an excess of 206Pb due to selective adsorption of 226Ra (and also Ba) into illite grains. This is a very rare example to show evidence of the selective adsorption behavior of Ra from the isotopic excesses of 206Pb, although the adsorption ability of Ra itself in nature was largely reported.

  9. Studies in Finishing Effects of Clay Mineral in Polymers and Synthetic Fibers

    Directory of Open Access Journals (Sweden)

    Faheem Uddin

    2013-01-01

    Full Text Available The use of clay mineral in modifying the properties of polymeric material is improved in application. The current interest in modifying the polymeric materials, particularly polyethylene, polypropylene, polystyrene, and nylon using clay mineral for improved flame retardancy, thermal stability, peak heat release rate, fracture, and strength properties generated significant research literature. This paper aims to review some of the important recent modification achieved in the performance of polymeric materials using organoclay mineral. Degradation of clay mineral-polymer (nm composite is discussed with appropriate known examples. Clay mineral (nm loading of 5 wt.% to 7 wt.% that was significantly smaller than the percent loading of conventional fillers in polymeric materials introduced significant improvement in terms of thermal and physical stability. An attempt is made to emphasize flammability and thermal stability and to indicate the areas that are relatively little explored in modification of fiber-forming polymers to enhance further research interest.

  10. A SEM, EDS and vibrational spectroscopic study of the clay mineral fraipontite.

    Science.gov (United States)

    Theiss, Frederick L; López, Andrés; Scholz, Ricardo; Frost, Ray L

    2015-08-01

    The mineral fraipontite has been studied by using a combination of scanning electron microscopy with energy dispersive analysis and vibrational spectroscopy (infrared and Raman). Fraipontite is a member of the 1:1 clay minerals of the kaolinite-serpentine group. The mineral contains Zn and Cu and is of formula (Cu,Zn,Al)₃(Si,Al)₂O₅(OH)₄. Qualitative chemical analysis of fraipontite shows an aluminium silicate mineral with amounts of Cu and Zn. This kaolinite type mineral has been characterised by Raman and infrared spectroscopy; in this way aspects about the molecular structure of fraipontite clay are elucidated.

  11. [Species Determination and Spectral Characteristics of Swelling Clay Minerals in the Pliocene Sandstones in Xinghai, Qinghai].

    Science.gov (United States)

    Wang, Chao-wen; Chen, Jiang-jun; Fang, Qian; Yin, Ke; Hong, Han-lie

    2015-10-01

    X-ray diffraction (XRD) and Fourier infrared absorption spectroscopy (FTIR) were conducted to deepen our research on specific species and spectral characteristics of swelling clay minerals in the Pliocene sandstones in Xinghai, Qinghai province. XRD results show that swelling clay minerals are dominant clay minerals in the sandstones, which can be up to 97% in percentage. XRD patterns show 060 reflections of the samples occur both remarkably at 1.534 Å and 1.498 Å, indicating the samples contain physical mixtures of trioctahedral and dioctahedral swelling clay minerals, respectively. Further treatment of Li-300 degrees C heat and glycerol saturation shows the swelling clay minerals collapse to 9.3-9.9 Å with a partial expansion to -18 Å. This indicates the swelling clay minerals dominate montmorillonite and contain minor saponite. The montmorillonite shows no swelling after Li-300 degrees C heat and glycerol saturation because of Li+ inserting into the octahedral layers, which balances the layer charge caused by the substitution of Mg to Al. FTIR results show the samples are composed of a kind of phyllosilicate with absorbed and structural water, which is in agreement with the results of XRD. Absorbed peaks at 913, 842, 880 cm(-1), corresponding to OH associated with Al-Al, Al-Mg, and Al-Fe pairs, further indicates the minerals are dominant dioctahedron in structure. Meanwhile, absorbed peaks at 625 and 519 cm(-1), corresponding to coupled Si-O and Al-O-Si deformation, indicates parts of Si is replaced by Al in tetrahedron. The spectral characteristics of the samples are against the presence of beidellite and nontronite based on the results of XRD and FTIR, while demonstrating an,existence of montmorillonite. This study, to distinguish the specific species of swelling clay species in clay minerals, would be of great importance when using clay mineralogy to interpret provenance and climatic information.

  12. Characteristics and genesis of clay minerals in the northern margin of the Qaidam Basin

    Institute of Scientific and Technical Information of China (English)

    Wang Linlin; Jiang Bo; Peng Dehua; Yin Chengming; Zeng Chunlin

    2011-01-01

    In order to develop appropriate reservoir protection measures in the northern margin of the Qaidam Basin and improve its oil and gas recovery efficiency, characteristics of clay minerals from eleven clay rock samples from the northern margin of the Qaidam Basin were investigated using X-ray diffraction analysis, the Scanning Electron Microscope (SEM) and energy spectrum analysis. Clay mineral composition and distribution characteristics of the main hydrocarbon reservoirs, I.e., from the Jurassic and Paleogene-Neogene, were explored. We analyzed the main factors which affected these attributes. The results show that the major clay minerals in the northern margin are chlorite, kaolinite, illite, smectite and illite/smectite inter-stratified minerals, Illite is the most widely spread clay mineral in this area.Chlorite is mainly found in the entire Neogene and in shallow horizons of the Paleogene. Smectite is enriched in the shallow Paleogene-Neogene. There are large amounts of kaolinite and illite/smectite inter-stratified minerals in the Jurassic. The major factors affecting the different development of clay minerals in the region are properties of parent rocks, paleoclimate and paleowater media conditions,diagenesis transformation, tectonic and terrain conditions.

  13. Heavy oil components sorbed onto clay minerals in Canadian oil sands

    Energy Technology Data Exchange (ETDEWEB)

    Fendel, A.; Schwochau, K. (Institute for Petroleum and Organic Geochemistry, Nuclear Research Centre (KFA), Julich (DE))

    1988-06-01

    In siliciclastic reservoir rocks the surface-active clay minerals are presumed to be predominantly responsible for the sorption of polar oil components. In order to achieve a better insight into the nature of the oil components sorbed onto clay minerals, unconsolidated Canadian Oil Sands (Cold Lake, Athabasca) were exhaustively extracted with dichloromethane to remove the free oil. The clay minerals (grain fraction less than or equal to2 ..mu..m) were then separated by gravitational sedimentation. After the extraction up to 3 wt of organic carbon still remained on the clays. The amount of aliphatic carbon adhering to the clays was assessed by means of IR-spectroscopy. The clay minerals were successively extracted with solvent mixtures of increasing polarity in order to release the bound oil components. The extracts were fractionated into chemically defined compound classes by semi-preparative liquid chromatography and MPLC. The fractions were characterized by GC, GC-MS and IR-spectroscopy. Components containing oxygen functions (carboxylic acids, esters, alcohols, ketones) appear to be preferentially bound by clays. Moreover, a small amount of hydrocarbons, in particular saturates, are sorbed by clays.

  14. Spatial distribution and longitudinal variation of clay minerals in the Central Indian Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Valsangkar, A.

    Grain size and clay mineral distribution up to 45 cm depth in the silty clay sediments from 26 box cores from 10 degrees to 16 degrees S along four longitudes (73.5 degrees-76.5 degrees E) were studied for understanding spatial variability...

  15. Clay mineral distributions in the southern Yellow Sea and their significance

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    To better understand the characteristics of the clay minerals in the southern Yellow Sea, the X-ray quantitative determinations have been carried out for the surface samples obtained from the Yellow Sea. With newly compiled clay mineral synoptic maps, the depositional processes were described for four main clay minerals (illite, chlorite, kaolinite and smectite). The analysis shows that most clay minerals are of terrigenous source with the Huanghe River acting as the major sediment supplier. Besides, the source of muddy sediments in the Yellow Sea was also discussed. As for the central Yellow Sea mud (CYSM), the sediments in its northern part mainly come from the Huanghe River, and those in the rest are of multi-origin. Very similarly, a large amount of sediments in the northern part of the southeastern Yellow Sea Mud (SEYSM) derive from the Keum River and Yeongsan River, while those in the southern part are of multi-origin.

  16. Clay mineral distribution in the continental shelf and slope off Saurashtra, West coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, V.P.

    the Deccan trap coastal province is the predominant clay mineral in the sediments of the continental shelf south of the Gulf of Kutch. Lateral variations reveal that the montmorillonite contents are high in the innershelf and on the continental slope...

  17. Clay Minerals as Solid Acids and Their Catalytic Properties.

    Science.gov (United States)

    Helsen, J.

    1982-01-01

    Discusses catalytic properties of clays, attributed to acidity of the clay surface. The formation of carbonium ions on montmorillonite is used as a demonstration of the presence of surface acidity, the enhanced dissociation of water molecules when polarized by cations, and the way the surface can interact with organic substances. (Author/JN)

  18. Thermal neutron absorption cross section and clay mineral content for Miocene Carpathian samples

    Science.gov (United States)

    Woznicka

    2000-12-01

    A correlation between the thermal neutron absorption cross section and the clay volume for samples from the chosen geological region is discussed. A comparison of the calculated and measured absorption cross sections as a function of clay volume allows an estimate to be made on the presence of highly absorbing impurities in clays. From the example presented, it was deduced that 105 ppm of B or 25 ppm of Gd in the clay minerals in the samples tested would be sufficient to explain the difference between the experimental and calculated cross sections.

  19. Lability of soil organic carbon in tropical soils with different clay minerals

    DEFF Research Database (Denmark)

    Bruun, Thilde Bech; Elberling, Bo; Christensen, Bent Tolstrup

    2010-01-01

    Soil organic carbon (SOC) storage and turnover is influenced by interactions between organic matter and the mineral soil fraction. However, the influence of clay content and type on SOC turnover rates remains unclear, particularly in tropical soils under natural vegetation. We examined the lability...... of SOC in tropical soils with contrasting clay mineralogy (kaolinite, smectite, allophane and Al-rich chlorite). Soil was sampled from A horizons at six sites in humid tropical areas of Ghana, Malaysian Borneo and the Solomon Islands and separated into fractions above and below 250 µm by wet sieving....... Basal soil respiration rates were determined from bulk soils and soil fractions. Substrate induced respiration rates were determined from soil fractions. SOC lability was significantly influenced by clay mineralogy, but not by clay content when compared across contrasting clay minerals. The lability...

  20. Enhanced cellular preservation by clay minerals in 1 billion-year-old lakes.

    Science.gov (United States)

    Wacey, David; Saunders, Martin; Roberts, Malcolm; Menon, Sarath; Green, Leonard; Kong, Charlie; Culwick, Timothy; Strother, Paul; Brasier, Martin D

    2014-01-01

    Organic-walled microfossils provide the best insights into the composition and evolution of the biosphere through the first 80 percent of Earth history. The mechanism of microfossil preservation affects the quality of biological information retained and informs understanding of early Earth palaeo-environments. We here show that 1 billion-year-old microfossils from the non-marine Torridon Group are remarkably preserved by a combination of clay minerals and phosphate, with clay minerals providing the highest fidelity of preservation. Fe-rich clay mostly occurs in narrow zones in contact with cellular material and is interpreted as an early microbially-mediated phase enclosing and replacing the most labile biological material. K-rich clay occurs within and exterior to cell envelopes, forming where the supply of Fe had been exhausted. Clay minerals inter-finger with calcium phosphate that co-precipitated with the clays in the sub-oxic zone of the lake sediments. This type of preservation was favoured in sulfate-poor environments where Fe-silicate precipitation could outcompete Fe-sulfide formation. This work shows that clay minerals can provide an exceptionally high fidelity of microfossil preservation and extends the known geological range of this fossilization style by almost 500 Ma. It also suggests that the best-preserved microfossils of this time may be found in low-sulfate environments.

  1. Clay mineral particles as effficient carriers of methylene blue used for antimicrobial treatment.

    Science.gov (United States)

    Bujdák, Juraj; Jureceková, Jana; Bujdákova, Helena; Lang, Kamil; Sersen, Frantisek

    2009-08-15

    There is a strong demand to identify new strategies for disinfection and treatment of human, animal, and plant pathogens. The presented work shows the potential of clay minerals to contribute to the development of novel disinfection materials. Enhanced antimicrobial effect of a photoactive organic dye, methylene blue (MB), in the colloids of clay mineral was observed. Singlet oxygen (1O2) formed upon visible light irradiation was detected directly using luminescence measurements atthe near-infrared region and by spin-trapping method. While MB adsorbed on clay colloid particles lost the ability to produce 1O2 due to molecular aggregation, surprisingly, the antimicrobial activity was significantly enhanced. Under visible light irradiation, MB/clay minerals dispersions prevented the sporulation of A. niger and Penicillium sp. and inhibited the growth of C. albicans by an additional 6-15% when compared with MB solution. In the experiments with E. coli, the efficiency of MB was increased by the reduction of surviving cells by 27 and 33%. S. aureus proved to be the most susceptible to MB/clay dispersions. Only less than 20% cells survived with respect to the control experiment at the low MB concentration (1.1 x 10(-6) mol dm(-3)). The contradiction between the significant antimicrobial properties of MB in clay colloidal systems and low 1O2 formation can be explained in terms of the photosensitization mechanism. The role of clay particles is most likely to promote the contact between microorganism cells and photoactive MB. Although the dye directly bound to the clay surface exhibits significantly reduced photoactivity, the presence of clay mediates the delivery of dye molecules on the surface or inside cells. The results indicate new perspectives of potential implementations of clay minerals as parts of complex disinfection materials for industrial applications or in understanding similar processes in nature.

  2. First-principles study of cesium adsorption to weathered micaceous clay minerals

    Science.gov (United States)

    Okumura, Masahiko; Nakamura, Hiroki; Machida, Masahiko

    2014-05-01

    , H. Nakamura, and M. Machida, Mechanism of Strong Affinity of Clay Minerals to Radioactive Cesium : First-Principles Calculation Study for Adsorption of Cesium at Frayed Edge Sites in Muscovite, Journal of the Physical Society of Japan 82, 033802 (2013).

  3. Micro and nano-size pores of clay minerals in shale reservoirs: Implication for the accumulation of shale gas

    Science.gov (United States)

    Chen, Shangbin; Han, Yufu; Fu, Changqin; Zhang, han; Zhu, Yanming; Zuo, Zhaoxi

    2016-08-01

    A pore is an essential component of shale gas reservoirs. Clay minerals are the adsorption carrier second only to organic matter. This paper uses the organic maturity test, Field-Emission Scanning Electron Microscopy (FE-SEM), and X-ray Diffraction (XRD) to study the structure and effect of clay minerals on storing gas in shales. Results show the depositional environment and organic maturity influence the content and types of clay minerals as well as their structure in the three types of sedimentary facies in China. Clay minerals develop multi-size pores which shrink to micro- and nano-size by close compaction during diagenesis. Micro- and nano-pores can be divided into six types: 1) interlayer, 2) intergranular, 3) pore and fracture in contact with organic matter, 4) pore and fracture in contact with other types of minerals, 5) dissolved and, 6) micro-cracks. The contribution of clay minerals to the presence of pores in shale is evident and the clay plane porosity can even reach 16%, close to the contribution of organic matter. The amount of clay minerals and pores displays a positive correlation. Clay minerals possess a strong adsorption which is affected by moisture and reservoir maturity. Different pore levels of clay minerals are mutually arranged, thus essentially producing distinct reservoir adsorption effects. Understanding the structural characteristics of micro- and nano-pores in clay minerals can provide a tool for the exploration and development of shale gas reservoirs.

  4. Potential bioavailability of mercury in humus-coated clay minerals.

    Science.gov (United States)

    Zhu, Daiwen; Zhong, Huan

    2015-10-01

    It is well-known that both clay and organic matter in soils play a key role in mercury biogeochemistry, while their combined effect is less studied. In this study, kaolinite, vermiculite, and montmorillonite were coated or not with humus, and spiked with inorganic mercury (IHg) or methylmercury (MeHg). The potential bioavailability of mercury to plants or deposit-feeders was assessed by CaCl2 or bovine serum albumin (BSA) extraction. For uncoated clay, IHg or MeHg extraction was generally lower in montmorillonite, due to its greater number of functional groups. Humus coating increased partitioning of IHg (0.5%-13.7%) and MeHg (0.8%-52.9%) in clay, because clay-sorbed humus provided more strong binding sites for mercury. Furthermore, humus coating led to a decrease in IHg (3.0%-59.8% for CaCl2 and 2.1%-5.0% for BSA) and MeHg (8.9%-74.6% for CaCl2 and 0.5%-8.2% for BSA) extraction, due to strong binding between mercury and clay-sorbed humus. Among various humus-coated clay particles, mercury extraction by CaCl2 (mainly through cation exchange) was lowest in humus-coated vermiculite, explained by the strong binding between humus and vermiculite. The inhibitory effect of humus on mercury bioavailability was also evidenced by the negative relationship between mercury extraction by CaCl2 and mercury in the organo-complexed fraction. In contrast, extraction of mercury by BSA (principally through complexation) was lowest in humus-coated montmorillonite. This was because BSA itself could be extensively sorbed onto montmorillonite. Results suggested that humus-coated clay could substantially decrease the potential bioavailability of mercury in soils, which should be considered when assessing risk in mercury-contaminated soils.

  5. Ground Truthing Orbital Clay Mineral Observations with the APXS Onboard Mars Exploration Rover Opportunity

    Science.gov (United States)

    Schroeder, C.; Gellert, R.; VanBommel, S.; Clark, B. C.; Ming, D. W.; Mittlefehldt, D. S.; Yen, A. S.

    2016-01-01

    NASA's Mars Exploration Rover Opportunity has been exploring approximately 22 km diameter Endeavour crater since 2011. Its rim segments predate the Hesperian-age Burns formation and expose Noachian-age material, which is associated with orbital Fe3+-Mg-rich clay mineral observations [1,2]. Moving to an orders of magnitude smaller instrumental field of view on the ground, the clay minerals were challenging to pinpoint on the basis of geochemical data because they appear to be the result of near-isochemical weathering of the local bedrock [3,4]. However, the APXS revealed a more complex mineral story as fracture fills and so-called red zones appear to contain more Al-rich clay minerals [5,6], which had not been observed from orbit. These observations are important to constrain clay mineral formation processes. More detail will be added as Opportunity is heading into her 10th extended mission, during which she will investigate Noachian bedrock that predates Endeavour crater, study sedimentary rocks inside Endeavour crater, and explore a fluid-carved gully. ESA's ExoMars rover will land on Noachian-age Oxia Planum where abundant Fe3+-Mg-rich clay minerals have been observed from orbit, but the story will undoubtedly become more complex once seen from the ground.

  6. Influence of Humic Acid on Interaction of Ammonium and Potassium Ions on Clay Minerals

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wen-Zhao; CHEN Xiao-Qin; ZHOU Jian-Min; LIU Dai-Huan; WANG Huo-Yan; DU Chang-Wen

    2013-01-01

    Interaction of ammonium (NH4+) and potassium (K+) is typical in field soils.However,the effects of organic matter on interaction of NH4+ and K+ have not been thoroughly investigated.In this study,we examined the changes in major physicochemical properties of three clay minerals (kaolinite,illite,and montmorillonite) after humic acid (HA) coating and evaluated the influences of these changes on the interaction of NH4+ and K+ on clay minerals using batch experiments.After HA coating,the cation exchange capacity (CEC) and specific surface area (SSA) of montmorillonite decreased significantly,while little decrease in CEC and SSA occurred in illite and only a slight increase in CEC was found in kaolinite.Humic acid coating significantly increased cation adsorption and preference for NH4+,and this effect was more obvious on clay minerals with a lower CEC.Results of Fourier transform infrared spectrometry analysis showed that HA coating promoted the formation of H-bonds between the adsorbed NH4+ and the organo-mineral complexes.HA coating increased cation fixation capacity on montmorillonite and kaolinite,but the opposite occurred on illite.In addition,HA coating increased the competitiveness of NH4+ on fixation sites.These results showed that HA coating affected both the nature of clay mineral surfaces and the reactions of NH4+ and K+ with clay minerals,which might influence the availability of nutrient cations to plants in field soils amended with organic matter.

  7. Alteration of non-swelling clay minerals and magadiite by acid activation

    NARCIS (Netherlands)

    Steudel, A.; Batenburg, L.F.; Fischer, H.R.; Weidler, P.G.; Emmerich, K.

    2009-01-01

    The bulk material of three kaolins, a sepiolite, an illite and one magadiite were treated with 1, 5 and 10 M H2SO4 at 80 °C for several hours. The alteration of the non-swelling clay mineral structures was controlled by the individual character of each mineral (chemical composition and initial parti

  8. [Analysis of XRD spectral characteristics of soil clay mineral in two typical cultivated soils].

    Science.gov (United States)

    Zhang, Zhi-Dan; Luo, Xiang-Li; Jiang, Hai-Chao; Li, Qiao; Shen, Cong-Ying; Liu, Hang; Zhou, Ya-Juan; Zhao, Lan-Po; Wang, Ji-Hong

    2014-07-01

    The present paper took black soil and chernozem, the typical cultivated soil in major grain producing area of Northeast, as the study object, and determinated the soil particle composition characteristics of two cultivated soils under the same climate and location. Then XRD was used to study the composition and difference of clay mineral in two kinds of soil and the evolutionary mechanism was explored. The results showed that the two kinds of soil particles were composed mainly of the sand, followed by clay and silt. When the particle accumulation rate reached 50%, the central particle size was in the 15-130 microm interval. Except for black soil profile of Shengli Xiang, the content of clay showed converse sequence to the central particle in two soils. Clay accumulated under upper layer (18.82%) in black soil profile while under caliche layer (17.41%) in chernozem profile. Clay content was the least in parent material horizon except in black profile of Quanyanling. Analysis of clay XRD atlas showed that the difference lied in not only the strength of diffraction peak, but also in the mineral composition. The main contents of black soil and chernozem were both 2 : 1 clay, the composition of black soil was smectite/illite mixed layer-illite-vermiculite and that of chernozem was S/I mixture-illite-montmorillonite, and both of them contained little kaolinite, chlorite, quartz and other primary mineral. This paper used XRD to determine the characteristics of clay minerals comprehensively, and analyzed two kinds of typical cultivated soil comparatively, and it was a new perspective of soil minerals study.

  9. Molecular Basis of Clay Mineral Structure and Dynamics in Subsurface Engineering Applications

    Science.gov (United States)

    Cygan, R. T.

    2015-12-01

    Clay minerals and their interfaces play an essential role in many geochemical, environmental, and subsurface engineering applications. Adsorption, dissolution, precipitation, nucleation, and growth mechanisms, in particular, are controlled by the interplay of structure, thermodynamics, kinetics, and transport at clay mineral-water interfaces. Molecular details of these processes are typically beyond the sensitivity of experimental and analytical methods, and therefore require accurate models and simulations. Also, basal surfaces and interlayers of clay minerals provide constrained interfacial environments to facilitate the evaluation of these complex processes. We have developed and used classical molecular and quantum methods to examine the complex behavior of clay mineral-water interfaces and dynamics of interlayer species. Bulk structures, swelling behavior, diffusion, and adsorption processes are evaluated and compared to experimental and spectroscopic findings. Analysis of adsorption mechanisms of radionuclides on clay minerals provides a scientific basis for predicting the suitability of engineered barriers associated with nuclear waste repositories and the fate of contaminants in the environment. Similarly, the injection of supercritical carbon dioxide into geological reservoirs—to mitigate the impact of climate change—is evaluated by molecular models of multi-fluid interactions with clay minerals. Molecular dynamics simulations provide insights into the wettability of different fluids—water, electrolyte solutions, and supercritical carbon dioxide—on clay surfaces, and which ultimately affects capillary fluid flow and the integrity of shale caprocks. This work is supported as part of Center for Frontiers of Subsurface Energy Security, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science and by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Geosciences Research Program

  10. Manganese(II)-catalyzed and clay-minerals-mediated reduction of chromium(VI) by citrate.

    Science.gov (United States)

    Sarkar, Binoy; Naidu, Ravi; Krishnamurti, Gummuluru S R; Megharaj, Mallavarapu

    2013-01-01

    Unlike lower valent iron (Fe), the potential role of lower valent manganese (Mn) in the reduction of hexavalent chromium (Cr(VI)) in soil is poorly documented. In this study, we report that citrate along with Mn(II) and clay minerals (montmorillonite and kaolinite) reduce Cr(VI) both in aqueous phase and in the presence of dissolved organic carbon (SDOC) extracted from a forest soil. The reduction was favorable at acidic pH (up to pH 5) and followed the pseudo-first-order kinetic model. The citrate (10 mM) + Mn(II) (182.02 μM) + clay minerals (3% w/v) system in SDOC accounted for complete reduction of Cr(VI) (192.32 μM) in about 72 h at pH 4.9. In this system, citrate was the reductant, Mn(II) was a catalyst, and the clay minerals acted as an accelerator for both the reductant and catalyst. The clay minerals also serve as a sink for Cr(III). This study reveals the underlying mechanism of the Mn(II)-induced reduction of Cr(VI) by organic ligand in the presence of clay minerals under certain environmental conditions.

  11. Effect of Clay Minerals on the Chemical Characteristics of Soil Humus

    Institute of Scientific and Technical Information of China (English)

    YEWEI; WENQIXIAO

    1996-01-01

    Chemical characteristics of humic substances in soils with different mineralogical characteristics and under different utilization paterns in Zhangpu,Fujian Province,together with two pairs of cultivated soils in North China Plain were studied by chemical analysis,visible and IR spectroscopy and 13C NMR spectrometry.For soils in Zhanpu the HA/FA ratio and both the aromaticity and the degree of humification of HA were higher in soils with montmorillonite as the predominant clay mineral than in those with kaolinite as the predominant clay mineral,provided these soils were under the same utilization pattern.While for each pair of soils with similar mineralogical characteristics the HA/FA ratio was higher and the C/H ratio and the contnet of carboxyl group of HA were lower in paddy soil than in upland soil.Among the upland soils(or paddy soils)studied the Ha/FA ratio of soil in Zhangpu with kaolinite as the predominant clay mineral was the lowest,and that of soil in Zhangpu with montmorillonite as the predominant clay mineral was the highest .the lowest.and that of soil in Zhangpu with montmorillonite as the predominant clay mineral was the highest It was concluded that the presence of montmorillonite favored the fromation and maturation of humic acid.

  12. Modeling of Cation Binding in Hydrated 2:1 Clay Minerals - Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Smith, David E.

    2000-09-14

    Hydrated 2:1 clay minerals are high surface area, layered silicates that play a unique role in determining the fate of radionuclides in the environment. This project consisted of developing and implementing computer simulation methods for molecular characterization of the swelling and ion exchange properties of Hydrated 2:1 clay minerals, and the subsequent analysis and theoretical modeling with a view toward improving contaminant transport modeling as well as soil remediation and radionuclide containment strategies. Project results included the (a) development of simulation methods to treat clays under environmentally relevant conditions of variable water vapor pressure; (b) calculation of clay swelling thermodynamics as a function of interlayer ion size and charge (calculated quantities include immersion energies, free energies, and entropies of swelling); and (c) calculation of ion exchange free energies, including contributions from changing interlayer water contents and layer spacing.

  13. CLAY MINERAL ASSEMBLAGES AND THEIR IMPLICATIONS IN SHIHEZI FORMATION FROM THE HUAIBEI COAL-BEARING STRATA

    Institute of Scientific and Technical Information of China (English)

    黄文辉; 许光泉; 刑军

    1998-01-01

    Clay mineral assemblages in Shihezi Formation of Huaibei coal-bearing strata are determined by X-ray diffraction and Differential Thermal Analyzer, that is restated to the sedimentfaces and climatic changes in the source area, and to a lesser extent, alterations during burial diagenesis. In the Upper Shihezi Formation, the clay fraction is dominated by kaolinite in norther npart of the coal field, which was formed in alluvial sediment environment. But in the South ofHuaibei coal field, the clay mineral assemblage consists of mainly illite that reflects the influenceof sea water. The predominately kaolinite and sederite composition of the clay fraction in the lower Shihezi Formation sediments documents less relief and gentle erosion of kaolinite rich soils developing under warm source area. In the lower part of Shihezi Formation, some chlorite is detected, which suggests transformation of illite or kaolinite to chlorite under conditions of burial diagenesis.

  14. Characterization of Clay Minerals and Kerogen in Alberta Oil Sands Geological End Members

    Science.gov (United States)

    Zheng, Limin

    The high degree of variability of oil sands ores can be attributed to a mixture of different geological end members, i.e., estuarine sand, estuarine clay, marine sand and marine clay. This study focused on the mineralogy, especially of clay minerals, and toluene insoluble organic matter, referred to as kerogen, in different oil sands end members. Clays and kerogens will likely have a significant impact on solvent recovery from the gangue following non-aqueous bitumen extraction. The bitumen-free solids were subjected to mineralogical and geochemical analysis. Kerogens were isolated and analyzed by various characterization methods. The types of clays were identified in oriented samples by X-ray diffraction analysis. The nitrogen to carbon ratio in the isolated kerogens is found to be higher than in bitumen. There are more type III kerogens in estuarine samples and more type II kerogens in marine samples.

  15. Characterization of Heat-treated Clay Minerals in the Context of Nuclear Waste Disposal

    Science.gov (United States)

    Matteo, E. N.; Wang, Y.; Kruichak, J. N.; Mills, M. M.

    2015-12-01

    Clay minerals are likely candidates to aid in nuclear waste isolation due to their low permeability, favorable swelling properties, and high cation sorption capacities. Establishing the thermal limit for clay minerals in a nuclear waste repository is a potentially important component of repository design, as flexibility of the heat load within the repository can have a major impact on the selection of repository design. For example, the thermal limit plays a critical role in the time that waste packages would need to cool before being transferred to the repository. Understanding the chemical and physical changes, if any, that occur in clay minerals at various temperatures above the current thermal limit (of 100 °C) can enable decision-makers with information critical to evaluating the potential trade-offs of increasing the thermal limit within the repository. Most critical is gaining understanding of how varying thermal conditions in the repository will impact radionuclide sorption and transport in clay materials either as engineered barriers or as disposal media. A variety of repository-relevant clay minerals (illite, mixed layer illite/smectite, and montmorillonite), were heated for a range of temperatures between 100-1000 °C. These samples were characterized to determine surface area, mineralogical alteration, and cation exchange capacity (CEC). Our results show that for conditions up to 500 °C, no significant change occurs, so long as the clay mineral remains mineralogically intact. At temperatures above 500 °C, transformation of the layered silicates into silica phases leads to alteration that impacts important clay characteristics. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's Nation Nuclear Security Administration under contract DE-AC04-94AL85000. SAND Number: SAND2015-6524 A

  16. Paleoenvironmental significance of clay mineral assemblages in the southeastern Arabian Sea during last 30 kyr

    Indian Academy of Sciences (India)

    Siddhartha Sankar Das; Ajai K Rai; Vaseem Akaram; Dhananjai Verma; A C Pandey; Koushik Dutta; G V Ravi Prasad

    2013-02-01

    A gravity core SK-221 recovered from the southeastern Arabian Sea near Laccadive–Chagos Ridge was examined to identify the sources of detrital clay minerals and to decipher paleoenvironmental changes for the last 30 kyr. The clay mineral assemblages predominantly consist of illite, kaolinite and chlorite with small amounts of smectite. Quartz, feldspar and occasionally gibbsite are the clay-sized non-clay minerals present in the examined section. The detrital clay minerals primarily originated from the hinterland and were supplied to the present site by the numerous small rivers draining western India during preglacial and Holocene periods, and partly by the strong reworking of Indian continental shelf during glacial period. The low values of humidity proxies (kaolinite content, kaolinite to illite and smectite to illite ratios) and better illite crystallinity indicate relatively weak summer monsoon condition that resulted in reduced chemical weathering during glacial period, which was interrupted by a discrete event of winter monsoon intensification at ∼20–17 ka. The increased kaolinite content, higher values of humidity indices and poorer illite crystallinity reflect high humidity that resulted in strong hydrolysis activity during the preglacial and Holocene periods. The increased CaCO3 during above periods also indicates less terrigenous dilution and intensified southwest monsoon-led upwelling which result in higher surface biogenic productivity. The characteristic clay mineral associations broadly suggest dry to semi-drier conditions during Heinrich Events H1, H2, and H3 and also during Younger Dryas. The low values of biogenic carbonate and organic carbon also indicate low productivity associated with weak summer monsoons during Heinrich Events. Abrupt increased humidity was recorded at 15–12.7 ka (Bølling/Allerød Event) sandwiched between two lows of Heinrich Events. Cycles of millennial timescale variations 2300, 1800, 1300 and 1000 yr have been

  17. Interaction of surface-modified silica nanoparticles with clay minerals

    Directory of Open Access Journals (Sweden)

    Cigdem Omurlu

    2016-05-01

    Full Text Available Abstract In this study, the adsorption of 5-nm silica nanoparticles onto montmorillonite and illite is investigated. The effect of surface functionalization was evaluated for four different surfaces: unmodified, surface-modified with anionic (sulfonate, cationic (quaternary ammonium (quat, and nonionic (polyethylene glycol (PEG surfactant. We employed ultraviolet–visible spectroscopy to determine the concentration of adsorbed nanoparticles in conditions that are likely to be found in subsurface reservoir environments. PEG-coated and quat/PEG-coated silica nanoparticles were found to significantly adsorb onto the clay surfaces, and the effects of electrolyte type (NaCl, KCl and concentration, nanoparticle concentration, pH, temperature, and clay type on PEG-coated nanoparticle adsorption were studied. The type and concentration of electrolytes were found to influence the degree of adsorption, suggesting a relationship between the interlayer spacing of the clay and the adsorption ability of the nanoparticles. Under the experimental conditions reported in this paper, the isotherms for nanoparticle adsorption onto montmorillonite at 25 °C indicate that adsorption occurs less readily as the nanoparticle concentration increases.

  18. Exploring biotic vs. abiotic controls on syngenetic carbonate and clay mineral precipitation

    Science.gov (United States)

    Nascimento, Gabriela S.; McKenzie, Judith A.; Martinez Ruiz, Francisca; Bontognali, Tomaso R. R.; Vasconcelos, Crisogono

    2016-04-01

    A possible syngenetic relationship between carbonate and clay mineral precipitation has been reported for sedimentary rocks deposited in both lacustrine and marine sedimentary environments throughout the geological record. In particular, the mineral dolomite is often found associated with Mg-rich clays, such as stevensite. It is notable that this carbonate/clay association has been recorded in numerous samples taken from modern dolomite precipitating environments; for example, the Coorong lakes, South Australia, coastal sabkhas, Abu Dhabi, UAE and coastal hypersaline lagoons (Lagoa Vermelha and Brejo do Espinho) east of Rio de Janeiro, Brazil. An HRTEM study of samples from these three locations indicates a possible physical/chemical association between the Ca-dolomite and Mg-rich clays, demonstrating a probable co-precipitation. To test this hypothesis, we have conducted a series of biotic and abiotic laboratory experiments. If this syngenesis actually occurs in nature, what, if any, are the biogeochemical processes controlling these precipitation reactions? Our experiments were designed to determine the extent of the biotic versus abiotic component influencing the mineral precipitation and, in the case of a biotic influence, to understand the mechanism through which microorganisms might mediate the formation of clay minerals. The experiments were carried out in the Geomicrobiology Laboratory of ETH Zürich using cultures of living microbes and artificial organic compounds that simulate functional groups present in natural biofilms formed under both aerobic and anaerobic conditions. In addition, pure inorganic experiments were designed to understand possible physico-chemical conditions for diagenetic processes that could induce dissolution of Mg-carbonates and precipitation of Mg-rich clays. Our results show a remarkable biotic influence during the formation of clay minerals. Specifically, extracellular polymeric substances (EPS), released by microbes in their

  19. Atom exchange between aqueous Fe(II) and structural Fe in clay minerals.

    Science.gov (United States)

    Neumann, Anke; Wu, Lingling; Li, Weiqiang; Beard, Brian L; Johnson, Clark M; Rosso, Kevin M; Frierdich, Andrew J; Scherer, Michelle M

    2015-03-03

    Due to their stability toward reductive dissolution, Fe-bearing clay minerals are viewed as a renewable source of Fe redox activity in diverse environments. Recent findings of interfacial electron transfer between aqueous Fe(II) and structural Fe in clay minerals and electron conduction in octahedral sheets of nontronite, however, raise the question whether Fe interaction with clay minerals is more dynamic than previously thought. Here, we use an enriched isotope tracer approach to simultaneously trace Fe atom movement from the aqueous phase to the solid ((57)Fe) and from the solid into the aqueous phase ((56)Fe). Over 6 months, we observed a significant decrease in aqueous (57)Fe isotope fraction, with a fast initial decrease which slowed after 3 days and stabilized after about 50 days. For the aqueous (56)Fe isotope fraction, we observed a similar but opposite trend, indicating that Fe atom movement had occurred in both directions: from the aqueous phase into the solid and from the solid into aqueous phase. We calculated that 5-20% of structural Fe in clay minerals NAu-1, NAu-2, and SWa-1 exchanged with aqueous Fe(II), which significantly exceeds the Fe atom layer exposed directly to solution. Calculations based on electron-hopping rates in nontronite suggest that the bulk conduction mechanism previously demonstrated for hematite1 and suggested as an explanation for the significant Fe atom exchange observed in goethite2 may be a plausible mechanism for Fe atom exchange in Fe-bearing clay minerals. Our finding of 5-20% Fe atom exchange in clay minerals indicates that we need to rethink how Fe mobility affects the macroscopic properties of Fe-bearing phyllosilicates and its role in Fe biogeochemical cycling, as well as its use in a variety of engineered applications, such as landfill liners and nuclear repositories.

  20. Role of clay minerals in the formation of atmospheric aggregates of Saharan dust

    Science.gov (United States)

    Cuadros, Javier; Diaz-Hernandez, José L.; Sanchez-Navas, Antonio; Garcia-Casco, Antonio

    2015-11-01

    Saharan dust can travel long distances in different directions across the Atlantic and Europe, sometimes in episodes of high dust concentration. In recent years it has been discovered that Saharan dust aerosols can aggregate into large, approximately spherical particles of up to 100 μm generated within raindrops that then evaporate, so that the aggregate deposition takes place most times in dry conditions. These aerosol aggregates are an interesting phenomenon resulting from the interaction of mineral aerosols and atmospheric conditions. They have been termed "iberulites" due to their discovery and description from aerosol deposits in the Iberian Peninsula. Here, these aggregates are further investigated, in particular the role of the clay minerals in the aggregation process of aerosol particles. Iberulites, and common aerosol particles for reference, were studied from the following periods or single dust events and locations: June 1998 in Tenerife, Canary Islands; June 2001 to August 2002, Granada, Spain; 13-20 August 2012, Granada; and 1-6 June 2014, Granada. Their mineralogy, chemistry and texture were analysed using X-ray diffraction, electron microprobe analysis, SEM and TEM. The mineral composition and structure of the iberulites consists of quartz, carbonate and feldspar grains surrounded by a matrix of clay minerals (illite, smectite and kaolinite) that also surrounds the entire aggregate. Minor phases, also distributed homogenously within the iberulites, are sulfates and Fe oxides. Clays are apparently more abundant in the iberulites than in the total aerosol deposit, suggesting that iberulite formation concentrates clays. Details of the structure and composition of iberulites differ from descriptions of previous samples, which indicates dependence on dust sources and atmospheric conditions, possibly including anthropic activity. Iberulites are formed by coalescence of aerosol mineral particles captured by precursor water droplets. The concentration of

  1. Reduction and immobilization of hexavalent chromium by microbially reduced Fe-bearing clay minerals

    Science.gov (United States)

    Bishop, Michael E.; Glasser, Paul; Dong, Hailiang; Arey, Bruce; Kovarik, Libor

    2014-05-01

    Hexavalent chromium (Cr6+) is a major contaminant in the environment. As a redox-sensitive element, the fate and toxicity of chromium is controlled by reduction-oxidation (redox) reactions. Previous research has shown the ability of structural Fe(II) in naturally present and chemically reduced clay minerals to reduce Cr6+ to Cr(III) as a way of immobilization and detoxification. However, it is still poorly known whether or not structural Fe(II) in biologically reduced clay minerals exhibits a similar reactivity and if so, what the kinetics and mechanisms of Cr6+ reduction are. The objective of this study was to determine the kinetics and possible mechanisms of Cr6+ reduction by structural Fe(II) in microbially reduced clay minerals and the nature of reduced Cr(III). Structural Fe(III) in nontronite (NAu-2), montmorillonite (SWy-2), chlorite (CCa-2), and clay-rich sediments from the Ringold Formation of the Hanford site of Washington State, USA was first bioreduced to Fe(II) by an iron-reducing bacterium Geobacter sulfurreducens with acetate as the sole electron donor and anthraquinone-2,6-disulfonate (AQDS) as electron shuttle in synthetic groundwater (pH 7). Biogenic Fe(II) was then used to reduce aqueous Cr6+ at three different temperatures, 10, 20, and 30 °C, in order to determine the temperature dependence of the redox reaction between Cr6+ and clay-Fe(II). The results showed that nontronite and montmorillonite were most effective in reducing aqueous Cr6+ at all three temperatures. In contrast, most Fe(II) in chlorite was not reactive towards Cr6+ reduction at 10 °C, though at 30 °C there was some reduction. For all the clay minerals, the ratio of total Fe(II) oxidized to Cr6+ reduced was close to the expected stoichiometric value of 3. Characterization of the Cr-clay reaction product with scanning electron microscopy with focused ion beam and transmission electron microscopy with electron energy loss spectroscopy revealed that reduced chromium was possibly

  2. Geochemical constraints on the presence of clay minerals in the Burns formation, Meridiani Planum, Mars

    Science.gov (United States)

    Cino, C. D.; Dehouck, E.; McLennan, S. M.

    2017-01-01

    Burns formation sandstones, deposited by aeolian processes and preserved at Meridiani Planum, Mars, contain abundant sulfate minerals. These sedimentary rocks are thought to be representative of a sulfate-rich geological epoch during late Noachian - early Hesperian time that followed an earlier clay-rich epoch. Twenty Burns formation targets, abraded by the Rock Abrasion Tool (RAT) and for which alpha-particle X-ray spectrometry (APXS) and Mössbauer spectroscopy data are available, were selected for geochemical modeling. A linear unmixing modeling approach was employed. Mineralogical constituents quantitatively constrained by Mössbauer and Mini-TES spectroscopy and interpreted to be chemically precipitated from aqueous fluids during deposition and/or early diagenesis were subtracted from the bulk chemistry. Resulting residual chemical compositions, interpreted to be dominated by detrital siliciclastic components and representing ∼21-35% of the rocks, were then geochemically evaluated to constrain the potential for the presence of clay minerals or their poorly-crystalline or non-crystalline precursors/chemical equivalents. Calculations incorporated a robust estimate of the uncertainties in mineral abundances. On Al2O3 - (CaO+Na2O) - K2O (A-CN-K) and Al2O3 - (CaO+Na2O+K2O) - (FeOtotal+MgO) (A-CNK-FM) molar ternary diagrams, removal of chemical constituents resulted in a shift from igneous-like compositions to compositions consistent with secondary mineral assemblages containing significant aluminous clay mineral components. All of the residual compositions are corundum-normative, further supportive of the presence of highly aluminous phases. On the A-CNK-FM diagram, clay minerals plotting closest to the residual field are natural montmorillonites but could also represent mixtures of various Mg/Fe-rich phyllosilicates, such as nontronite or saponite, and other more Al-rich minerals such as Al-montmorillonite, kaolinite or illite. Depending on the age of clay

  3. Rheological properties of different minerals and clay soils

    Directory of Open Access Journals (Sweden)

    Dolgor Khaydapova

    2015-07-01

    Full Text Available Rheological properties of kaolinite, montmorillonite, ferralitic soil of the humid subtropics (Norfolk island, southwest of Oceania, alluvial clay soil of arid subtropics (Konyaprovince, Turkey and carbonate loess loam of Russian forest-steppe zone were determined. A parallel plate rheometer MCR-302 (Anton Paar, Austria was used in order to conduct amplitude sweep test. Rheological properties allow to assess quantitatively structural bonds and estimate structural resistance to a mechanical impact. Measurements were carried out on samples previously pounded and capillary humidified during 24 hours. In the amplitude sweep method an analyzed sample was placed between two plates. The upper plate makes oscillating motions with gradually extending amplitude. Software of the device allows to receive several rheological parameters such as elastic modulus (G’, Pa, viscosity modulus (G", Pa, linear viscoelasticity range (G’>>G”, and point of destruction of structure at which the elastic modulus becomes equal to the viscosity modulus (G’=G”- crossover. It was found out that in the elastic behavior at G '>> G " strength of structural links of kaolinite, alluvial clay soil and loess loam constituted one order of 105 Pa. Montmorillonit had a minimum strength - 104 Pa and ferrallitic soil of Norfolk island [has] - a maximum one -106 Pa. At the same time montmorillonite and ferralitic soil were characterized by the greatest plasticity. Destruction of their structure (G '= G" took place only in the cases when strain was reaching 11-12%. Destraction of the kaolinite structure happened at 5% of deformation and of the alluvial clay soil and loess loam - at 4.5%.

  4. Networking and rheology of concentrated clay suspensions "matured" in mineral medicinal water.

    Science.gov (United States)

    Aguzzi, Carola; Sánchez-Espejo, Rita; Cerezo, Pilar; Machado, José; Bonferoni, Cristina; Rossi, Silvia; Salcedo, Inmaculada; Viseras, César

    2013-09-10

    This work studied the influence of "maturation" conditions (time and agitation) on aggregation states, gel structure and rheological behaviour of a special kind of pharmaceutical semisolid products made of concentrated clay suspensions in mineral medicinal water. Maturation of the samples was carried out in distilled and sulphated mineral medicinal water, both in static conditions (without agitation) and with manual stirring once a week, during a maximum period of three months. At the measured pH interval (7.5-8.0), three-dimensional band-type networks resulting from face/face contacts were predominant in the laminar (disc-like) clay suspensions, whereas the fibrous (rod-like) particles formed micro-aggregates by van der Waals attractions. The high concentration of solids in the studied systems greatly determined their behaviour. Rod-like sepiolite particles tend to align the major axis in aggregates promoted by low shearing maturation, whereas aggregates of disc-like smectite particles did not have a preferential orientation and their complete swelling required long maturation time, being independent of stirring. Maturation of both kinds of suspensions resulted in improved rheological properties. Laminar clay suspensions became more structured with time, independently from static or dynamic maturation conditions, whereas for fibrous clay periodic agitation was also required. Rheological properties of the studied systems have been related to aggregation states and networking mechanisms, depending on the type of clay minerals constituents. Physical stability of the suspensions was not impaired by the specific composition of the Graena medicinal water.

  5. Experimental Constraints on Microbial Liberation of Structural Iron from Common Clay Minerals in Marine Sediments

    Science.gov (United States)

    Metcalfe, K. S.; Gaines, R. R.; Trang, J.; Scott, S. W.; Crane, E. J.; Lackey, J.; Prokopenko, M. G.; Berelson, W.

    2013-12-01

    Iron is a limiting nutrient in many marine settings. The marine Fe-cycle is complex because Fe may be used as an electron donor or acceptor and cycled many times before ultimate burial in sediments. Thus, the availability of iron plays a large role in the marine carbon cycle, influencing not only the extent of primary productivity but also the oxidation of organic matter in sediments. The primary constituents of marine sediments are clay minerals, which commonly contain lattice-bound Fe in octahedral sites. In marine settings, the pool of Fe bound within silicate mineral lattices has long been considered reactive only over long timescales, and thus non-bioavailable. In vitro experimental evidence has shown that lab cultures of Fe-reducing bacteria are able to utilize structurally-bound Fe (III) from the crystal lattice of nontronite, an uncommon but particularly Fe-rich (> 12 wt.%) smectite. Importantly, this process is capable of liberating Fe (II) to solution, where it is available to biotic processes as an electron donor. In order to constrain the capacity of naturally-occurring marine bacteria to liberate structurally-coordinated Fe from the lattices of common clay minerals, we exposed a suite of 16 different clay minerals (0.8-13.9 wt.% Fe) to lab cultures of known Fe-reducer S. onenidensis MR-1 and to a natural consortium of Fe-reducing microbes from the San Pedro and Santa Monica Basins over timescales ranging from 7-120 days. Clay minerals were treated with Na-dithionite to extract surface-bound Fe prior to exposure. Crystallographic data and direct measurements of Fe in solution demonstrate the release of structural Fe from all clay minerals analyzed. Neoformation of illite and amorphous quartz were observed. The array of clay minerals and microbes used in this experiment complement past findings and suggest that common clay minerals may represent a large and previously unrecognized pool of bioavailable Fe in the world ocean that contributes significantly

  6. Cambrian burgess shale animals replicated in clay minerals

    Science.gov (United States)

    Orr; Briggs; Kearns

    1998-08-21

    Although the evolutionary importance of the Burgess Shale is universally acknowledged, there is disagreement on the mode of preservation of the fossils after burial. Elemental mapping demonstrates that the relative abundance of elements varies between different anatomical features of the specimens. These differences reflect the compositions of the minerals that replicated the decaying organism, which were controlled by contrasts in tissue chemistry. Delicate morphological details are replicated in the elemental maps, showing that authigenic mineralization was fundamental to preserving these fossils, even though some organic remains are also present.

  7. Heterogeneous uptake of the C1 to C4 organic acids on a swelling clay mineral

    Directory of Open Access Journals (Sweden)

    M. A. Tolbert

    2007-08-01

    Full Text Available Mineral aerosol is of interest due to its physiochemical impacts on the Earth's atmosphere. However, adsorbed organics could influence the chemical and physical properties of atmospheric mineral particles and alter their impact on the biosphere and climate. In this work, the heterogeneous uptake of a series of small organic acids on the swelling clay, Na-montmorillonite, was studied at 212 K as a function of relative humidity (RH, organic acid pressure and clay mass. A high vacuum chamber equipped with a quadrupole mass spectrometer and a transmission Fourier transform infrared spectrometer was used to detect the gas and condensed phases, respectively. Our results show that while the initial uptake efficiency was found to be independent of organic acid pressure, it increased linearly with increasing clay mass. Thus, the small masses studied allow access to the entire surface area of the clay sample with minimal effects due to surface saturation. Additionally, results from this study show that the initial uptake efficiency for butanoic (butyric acid on the clay increases by an order of magnitude as the RH is raised from 0% to 45% RH at 212 K while the initial uptake efficiency of formic, acetic and propanoic (propionic acids increases only slightly at higher humidities. However, the initial uptake efficiency decreases significantly in a short amount of time due to surface saturation effects. Thus, although the initial uptake efficiencies are appropriate for initial times, the fact that the uptake efficiency will decrease over time as the surface saturates should be considered in atmospheric models. Surface saturation results in sub-monolayer coverage of organic acid on montmorillonite under dry conditions and relevant organic acid pressures that increases with increasing humidity for all organic acids studied. Additionally, the presence of large organic acids may slightly enhance the water content of the clay above 45% RH. Our results indicate

  8. Modeling selenate adsorption behavior on oxides, clay minerals, and soils using the triple layer model

    Science.gov (United States)

    Selenate adsorption behavior was investigated on amorphous aluminum oxide, amorphous iron oxide, goethite, clay minerals: kaolinites, montmorillonites, illite, and 18 soil samples from Hawaii, and the Southwestern and the Midwestern regions of the US as a function of solution pH. Selenate adsorpti...

  9. Clay minerals assemblage in the Neogene fluvial succession of the Pishin Belt, Pakistan

    DEFF Research Database (Denmark)

    Kasi, Aimal Khan; Kassi, Akhtar Muhammad; Friis, Henrik

    2014-01-01

    and metasedimentary successions. The source of kaolinite seems to be pedogenic or lateritic. The clay minerals assemblage in mudstones and sandstones of the Dasht Murgha group, Malthanai formation and Bostan formation appears to have been derived from the nearby-exposed Pre-Miocence mafic/ultramafic rocks...

  10. Sedimentological and clay mineral studies in Kakinada Bay, east coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Reddy, N.P.C.; Rao, K.M.

    are of sandy sediments (2.9 to 3.05 phi). Interrelationships of size statistical parameters and the CM diagram of the bay sediments suggest a mechanism of slow deposition from quiet water. Montmorillonite is the predominant clay mineral followed by kaolinite...

  11. Clay mineral stratigraphy of Miocene to recent marine sediments in the central Mediterranean

    NARCIS (Netherlands)

    Visser, J.P. de

    1992-01-01

    X-ray diffraction analyses were made of the smaller than 2 J..Lm fraction from about 1250 samples of the central Mediterranean Miocene to Recent and the southeastern North-Atlantic Miocene in order to reconstruct climatic changes. Relative quantities of the clay minerals chlorite, illite, pyrophylli

  12. Modeling selenite adsorption envelopes on oxides, clay minerals, and soils using the triple layer model

    Science.gov (United States)

    Selenite adsorption behavior was investigated on amorphous aluminum and iron oxides, clay minerals: kaolinite, montmorillonite, and illite, and 45 surface and subsurface soil samples from the Southwestern and Midwestern regions of the USA as a function of solution pH. Selenite adsorption decreased ...

  13. Clay Mineral Distribution Patterns of Tertiary Continental Oil-bearing Basins in China

    Institute of Scientific and Technical Information of China (English)

    Zhao Xingyuan

    1996-01-01

    @@ Induction This paper studies the clay mineral distribution patterns of Tertiary continental oil-bearing basins in China. More than 9 000 shale samples from Paleogene (E) to Neogene (N) Series distributed in Bohai Gulf, Subei, Jianghan,Nanxiang, Zhoukou, Sanshui, Beibu Bay, East China Sea,Hetao, Juiquan, Qaidam and Tarim basins, and so on.

  14. Spectral characteristics of clay minerals in the 2.5 - 14 µm wavelength region

    NARCIS (Netherlands)

    Yitagesu, F.A.; Meer, F.D. van der; Werff, H.M.A. van der; Hecker, C.A.

    2011-01-01

    Identification and quantification of clay minerals, particularly those that are responsible for susceptibility of soils to expansion and shrinkage, is a constant focus of research in geotechnical engineering. The visible, near infrared and short wave infrared wavelength regions are well explored. Ho

  15. Discussion on origin of clay minerals in outcropped sandstone from Lower Cretaceous Chengzihe Formation and Muling Formation in Jixi Basin

    Institute of Scientific and Technical Information of China (English)

    LIU Jianying; LIU Li; QU Xiyu

    2009-01-01

    Clay minerals in the outcropped sandstone from Lower Cretaceous Chengzihe Formation and Muling Formation in Jixi Basin were analyzed by X-ray diffraction. The results show that the clay minerals mainly consist of illite, kaollinite and illite/smectite, which can be divided into two types: kaolinite- and illite/smectite types. The outcropped sandstone occurred in middle diagenetic stage-A on the basis of the clay mineral composition. The development factor of the formation of kaolinite type clay mineral is caused mainly by the organic acid from the coal-bearing formation and mudstone during the diagenesis process in Lower Cretaceous Chengzihe Formation and Muling Formation in the Jixi Basin. The weak hydrodynamic force of sedimentary facies made the sandstone leaching condition poor, which is the reason forming the aggregation of clay minerals of the illite/smectite-and illite types.

  16. Clay minerals in primitive meteorites and interplanetary dust 1

    Science.gov (United States)

    Zolensky, M. E.; Keller, L. P.

    1991-01-01

    Many meteorites and interplanetary dust particles (IDPs) with primitive compositions contain significant amounts of phyllosilicate minerals, which are generally interpreted as evidence of protoplanetary aqueous alteration at an early period of the solar system. These meteorites are chondrites (near solar composition) of the carbonaceous and ordinary varieties. The former are subdivided (according to bulk composition and petrology) into CI, CM, CV, CO, CR, and ungrouped classes. IDPs are extraterrestrial particulates, collected in stratosphere, which have chemical compositions indicative of a primitive origin; they are typically distinct from the primitive meteorites. Characterization of phyllosilicates in these materials is a high priority because of the important physico-chemical information they hold. The most common phyllosilicates present in chondritic extraterrestrial materials are serpentine-group minerals, smectites, and micas. We discuss these phyllosilicates and describe the interpretation of their occurrence in meteorites and IDPs and what this indicates about history of their parent bodies, which are probably the hydrous asteroids.

  17. Microwave processing of oil sands and contribution of clay minerals

    OpenAIRE

    John P. Robinson; Binner, Eleanor; Saeid, Abdul; Al-Harahsheh, Mohammad; Kingman, S. W.

    2014-01-01

    This study establishes the feasibility of microwave heating for extracting oil from Oil Sands in ex-situ processes. Previous studies in this area have shown some potential, but have not characterised the dielectric properties of the Oil Sands used, nor related them to the mineral composition, both of which are vital if successful scale up is to be achieved. In this work the fundamental interactions of microwave energy with Oil Sands are investigated and understood for the first time, and the ...

  18. Cesium adsorption/desorption behavior of clay minerals considering actual contamination conditions in Fukushima

    Science.gov (United States)

    Mukai, Hiroki; Hirose, Atsushi; Motai, Satoko; Kikuchi, Ryosuke; Tanoi, Keitaro; Nakanishi, Tomoko M.; Yaita, Tsuyoshi; Kogure, Toshihiro

    2016-02-01

    Cesium adsorption/desorption experiments for various clay minerals, considering actual contamination conditions in Fukushima, were conducted using the 137Cs radioisotope and an autoradiography using imaging plates (IPs). A 50 μl solution containing 0.185 ~ 1.85 Bq of 137Cs (10-11 ~ 10-9 molL-1 of 137Cs) was dropped onto a substrate where various mineral particles were arranged. It was found that partially-vermiculitized biotite, which is termed “weathered biotite” (WB) in this study, from Fukushima sorbed 137Cs far more than the other clay minerals (fresh biotite, illite, smectite, kaolinite, halloysite, allophane, imogolite) on the same substrate. When WB was absent on the substrate, the amount of 137Cs sorbed to the other clay minerals was considerably increased, implying that selective sorption to WB caused depletion of radiocesium in the solution and less sorption to the coexisting minerals. Cs-sorption to WB continued for about one day, whereas that to ferruginous smectite was completed within one hour. The sorbed 137Cs in WB was hardly leached with hydrochloric acid at pH 1, particularly in samples with a longer sorption time. The presence/absence of WB sorbing radiocesium is a key factor affecting the dynamics and fate of radiocesium in Fukushima.

  19. Cesium adsorption/desorption behavior of clay minerals considering actual contamination conditions in Fukushima.

    Science.gov (United States)

    Mukai, Hiroki; Hirose, Atsushi; Motai, Satoko; Kikuchi, Ryosuke; Tanoi, Keitaro; Nakanishi, Tomoko M; Yaita, Tsuyoshi; Kogure, Toshihiro

    2016-01-01

    Cesium adsorption/desorption experiments for various clay minerals, considering actual contamination conditions in Fukushima, were conducted using the (137)Cs radioisotope and an autoradiography using imaging plates (IPs). A 50 μl solution containing 0.185 ~ 1.85 Bq of (137)Cs (10(-11) ~ 10(-9 )molL(-1) of (137)Cs) was dropped onto a substrate where various mineral particles were arranged. It was found that partially-vermiculitized biotite, which is termed "weathered biotite" (WB) in this study, from Fukushima sorbed (137)Cs far more than the other clay minerals (fresh biotite, illite, smectite, kaolinite, halloysite, allophane, imogolite) on the same substrate. When WB was absent on the substrate, the amount of (137)Cs sorbed to the other clay minerals was considerably increased, implying that selective sorption to WB caused depletion of radiocesium in the solution and less sorption to the coexisting minerals. Cs-sorption to WB continued for about one day, whereas that to ferruginous smectite was completed within one hour. The sorbed (137)Cs in WB was hardly leached with hydrochloric acid at pH 1, particularly in samples with a longer sorption time. The presence/absence of WB sorbing radiocesium is a key factor affecting the dynamics and fate of radiocesium in Fukushima.

  20. Influence of Water Content on the Mechanical Behaviour of Limestone: Role of the Clay Minerals Content

    Science.gov (United States)

    Cherblanc, F.; Berthonneau, J.; Bromblet, P.; Huon, V.

    2016-06-01

    The mechanical characteristics of various sedimentary stones significantly depend on the water content, where 70 % loss of their mechanical strengths can be observed when saturated by water. Furthermore, the clay fraction has been shown to be a key factor of their hydro-mechanical behaviour since it governs for instance the hydric dilation. This work aims at investigating the correlations between the clay mineral content and the mechanical weakening experienced by limestones when interacting with water. The experimental characterization focuses on five different limestones that exhibit very different micro-structures. For each of them, we present the determination of clay mineral composition, the sorption isotherm curve and the dependences of tensile and compressive strengths on the water content. It emerges from these results that, first, the sorption behaviour is mainly governed by the amount of smectite layers which exhibit the larger specific area and, second, the rate of mechanical strength loss depends linearly on the sorption capacity. Indeed, the clay fraction plays the role of a retardation factor that delays the appearance of capillary bridges as well as the mechanical weakening of stones. However, no correlation was evidenced between the clay content and the amplitude of weakening. Since the mechanisms whereby the strength decreases with water content are not clearly established, these results would help to discriminate between various hypothesis proposed in the literature.

  1. Bioreduction of Fe-bearing clay minerals and their reactivity toward pertechnetate (Tc-99)

    Energy Technology Data Exchange (ETDEWEB)

    Bishop, Michael E.; Dong, Hailiang; Kukkadapu, Ravi K.; Liu, Chongxuan; Edelmann, Richard E.

    2011-07-01

    99Technetium (99Tc) is a fission product of uranium-235 and plutonium-239 and poses a high environmental hazard due to its long half-life (t1/2 = 2.13 x 105 y), abundance in nuclear wastes, and environmental mobility under oxidizing conditions [i.e., Tc(VII)]. Under reducing conditions, Tc(VII) can be reduced to insoluble Tc(IV). Ferrous iron [Fe(II)], either in aqueous form or in mineral form, has been used to reduce Tc(VII) to Tc(IV). However, the reactivity of Fe(II) from clay minerals, other than nontronite, toward immobilization of Tc(VII) and its role in retention of reduced Tc(IV) have not been investigated. In this study the reactivity of a suite of clay minerals toward Tc(VII) reduction and immobilization was evaluated. The clay minerals chosen for this study included five members in the smectite-illite (S-I) series, (montmorillonite, nontronite, rectorite, mixed layered I-S, and illite), chlorite, and palygorskite. Fe-oxides were removed from these minerals with a modified dithionite-citrate-bicarbonate (DCB) procedure. The total Fe content of these clay minerals, after Fe-oxide removal, ranged from 0.7 to 30.4% by weight, and the Fe(III)/Fe(total) ratio ranged from 44.9 to 98.5%. X-ray diffraction (XRD) and Mössbauer spectroscopy results showed that after Fe oxide removal the clay minerals were free of Fe-oxides. Scanning electron microscopy (SEM) revealed that little dissolution occurred during the DCB treatment. Bioreduction experiments were performed in bicarbonate buffer (pH-7) with Fe(III) in the clay minerals as the sole electron acceptor, lactate as the sole electron donor, and Shewanella Putrifaciens CN32 cells as mediators. In select tubes, anthraquinone-2,6-disulfate (AQDS) was added as electron shuttle to facilitate electron transfer. The extent of Fe(III) bioreduction was the highest for chlorite (~43 wt%) and the lowest for palygorskite (~4.17 wt%). In the S-I series, NAu-2 was the most reducible (~31 %) and illite the least (~0.4 %). The

  2. Investigating the Thermal Limit of Clay Minerals for Applications in Nuclear Waste Repository Design

    Science.gov (United States)

    Matteo, E. N.; Miller, A. W.; Kruichak, J.; Mills, M.; Tellez, H.; Wang, Y.

    2013-12-01

    Clay minerals are likely candidates to aid in nuclear waste isolation due to their low permeability, favorable swelling properties, and high cation sorption capacities. Establishing the thermal limit for clay minerals in a nuclear waste repository is a potentially important component of repository design, as flexibility of the heat load within the repository can have a major impact on the selection of repository design. For example, the thermal limit plays a critical role in the time that waste packages would need to cool before being transferred to the repository. Understanding the chemical and physical changes that occur in clay minerals at various temperatures above the current thermal limit (of 100 °C) can enable decision-makers with information critical to evaluating the potential trade-offs of increasing the thermal limit within the repository. Most critical is gaining understanding of how varying thermal conditions in the repository will impact radionuclide sorption and transport in clay materials either as engineered barriers or as disposal media. A variety of clays (illite, mixed layer illite/smectite, montmorillonite, and palygorskite) were heated for a range of temperatures between 100-500 °C. These samples were characterized by a variety of methods, including nitrogen adsorption, x-ray diffraction, thermogravimetric analysis, barium chloride exchange for cation exchange capacity (CEC), and iodide sorption. The nitrogen porosimetry shows that for all the clays, thermally-induced changes in BET surface area are dominated by collapse/creation of the microporosity, i.e. pore diameters Security Administration under contract DE-AC04-94AL85000. SAND Number: 2013-6352A.

  3. Clay mineral association in the salt formation of the Transylvanian Basin and its paleoenvironmental significance

    Directory of Open Access Journals (Sweden)

    Nicoleta Bican-Bris̡an

    2006-04-01

    Full Text Available The investigated clay fraction was separated from salt samples recovered from three boreholes located in the Praid salt deposit area. For comparison, samples collected from Turda deposit (Franz Josef adit, the Rudolf and Ghizele chambers and from the salt massif from Sărăţel were also analyzed. The qualitative investigations evidenced a clay minerals association dominated by illite and chlorite accompanied by subordinate amounts of kaolinite, smectite, fibrous clays (sepiolite, palygorskite, and in minor amounts, by 14/14 chlorite/vermiculite and chlorite/smectite interstratifications. A quantitative evaluation (% including a standard graphical representation was performed only for the borehole samples (Praid, according to the vertical distribution. The genetical interpretation of the identified clay minerals association took into account the influence of the sedimentation mechanisms and the climate control on the mineral phases. The environment of formation for the salt in the Transylvanian Basin was defined by the presence of specific climatic factors, also suggested by the palynological investigations.

  4. Modified clay minerals efficiency against chemical and biological warfare agents for civil human protection.

    Science.gov (United States)

    Plachá, Daniela; Rosenbergová, Kateřina; Slabotínský, Jiří; Kutláková, Kateřina Mamulová; Studentová, Soňa; Martynková, Gražyna Simha

    2014-04-30

    Sorption efficiencies of modified montmorillonite and vermiculite of their mono ionic Na and organic HDTMA and HDP forms were studied against chemical and biological warfare agents such as yperite and selected bacterial strains. Yperite interactions with modified clay minerals were observed through its capture in low-density polyethylene foil-modified clay composites by measuring yperite gas permeation with using chemical indication and gas chromatography methods. The antibacterial activities of synthetized organoclays were tested against selected Gram-positive and Gram-negative bacterial species in minimum inhibitory concentration tests. The obtained results showed a positive influence of modified clay minerals on the significant yperite breakthrough-time increase. The most effective material was the polyethylene-Na form montmorillonite, while the polyethylene-Na form vermiculite showed the lowest efficiency. With increasing organic cations loading in the interlayer space the montmorillonite efficiency decreased, and in the case of vermiculite an opposite effect was observed. Generally the modified montmorillonites were more effective than modified vermiculites. The HDP cations seem to be more effective compare to the HDTMA. The antibacterial activity tests confirmed efficiency of all organically modified clay minerals against Gram-positive bacteria. The confirmation of antibacterial activity against Y. pestis, plague bacteria, is the most interesting result of this part of the study.

  5. Bioremediating oil spills in nutrient poor ocean waters using fertilized clay mineral flakes: some experimental constraints.

    Science.gov (United States)

    Warr, Laurence N; Friese, André; Schwarz, Florian; Schauer, Frieder; Portier, Ralph J; Basirico, Laura M; Olson, Gregory M

    2013-01-01

    Much oil spill research has focused on fertilizing hydrocarbon oxidising bacteria, but a primary limitation is the rapid dilution of additives in open waters. A new technique is presented for bioremediation by adding nutrient amendments to the oil spill using thin filmed minerals comprised largely of Fullers Earth clay. Together with adsorbed N and P fertilizers, filming additives, and organoclay, clay flakes can be engineered to float on seawater, attach to the oil, and slowly release contained nutrients. Our laboratory experiments of microbial activity on weathered source oil from the Deepwater Horizon spill in the Gulf of Mexico show fertilized clay treatment significantly enhanced bacterial respiration and consumption of alkanes compared to untreated oil-in-water conditions and reacted faster than straight fertilization. Whereas a major portion (up to 98%) of the alkane content was removed during the 1 month period of experimentation by fertilized clay flake interaction; the reduced concentration of polyaromatic hydrocarbons was not significantly different from the non-clay bearing samples. Such clay flake treatment could offer a way to more effectively apply the fertilizer to the spill in open nutrient poor waters and thus significantly reduce the extent and duration of marine oil spills, but this method is not expected to impact hydrocarbon toxicity.

  6. Bioremediating Oil Spills in Nutrient Poor Ocean Waters Using Fertilized Clay Mineral Flakes: Some Experimental Constraints

    Directory of Open Access Journals (Sweden)

    Laurence N. Warr

    2013-01-01

    Full Text Available Much oil spill research has focused on fertilizing hydrocarbon oxidising bacteria, but a primary limitation is the rapid dilution of additives in open waters. A new technique is presented for bioremediation by adding nutrient amendments to the oil spill using thin filmed minerals comprised largely of Fullers Earth clay. Together with adsorbed N and P fertilizers, filming additives, and organoclay, clay flakes can be engineered to float on seawater, attach to the oil, and slowly release contained nutrients. Our laboratory experiments of microbial activity on weathered source oil from the Deepwater Horizon spill in the Gulf of Mexico show fertilized clay treatment significantly enhanced bacterial respiration and consumption of alkanes compared to untreated oil-in-water conditions and reacted faster than straight fertilization. Whereas a major portion (up to 98% of the alkane content was removed during the 1 month period of experimentation by fertilized clay flake interaction; the reduced concentration of polyaromatic hydrocarbons was not significantly different from the non-clay bearing samples. Such clay flake treatment could offer a way to more effectively apply the fertilizer to the spill in open nutrient poor waters and thus significantly reduce the extent and duration of marine oil spills, but this method is not expected to impact hydrocarbon toxicity.

  7. Iron-rich clay minerals on Mars - Potential sources or sinks for hydrogen and indicators of hydrogen loss over time

    Science.gov (United States)

    Burt, D. M.

    1989-01-01

    Although direct evidence is lacking, indirect evidence suggests that iron-rich clay minerals or poorly-ordered chemical equivalents are widespread on the Martian surface. Such clays can act as sources or sinks for hydrogen ('hydrogen sponges'). Ferrous clays can lose hydrogen and ferric clays gain it by the coupled substitution Fe(3+)O(Fe(2+)OH)-1, equivalent to minus atomic H. This 'oxy-clay' substitution involves only proton and electron migration through the crystal structure, and therefore occurs nondestructively and reversibly, at relatively low temperatures. The reversible, low-temperature nature of this reaction contrasts with the irreversible nature of destructive dehydroxylation (H2O loss) suffered by clays heated to high temperatures. In theory, metastable ferric oxy-clays formed by dehydrogenation of ferrous clays over geologic time could, if exposed to water vapor, extract the hydrogen from it, releasing oxygen.

  8. Structural Transformation of Clay Minerals by a New Molecular Dynamics Simulation Method

    Science.gov (United States)

    Wang, Jianfeng; Gutierrez, Marte

    2010-05-01

    A MD simulation study of 2:1 clay minerals is carried out using a new MD simulation method which is capable of simulating a system under the most general external stress conditions by considering the changes of MD cell size and shape. The tensor defining the cell size and shape is correlated with the atomic level stress tensors (both internal and external) through a Lagrangian formulation. Due to this feature, the method is able to predict the crystal transformation of molecular structures which is compatible with the imposed external stress and boundary conditions. In this paper, the new method has been applied for the first time to the simulations of dehydrated montmorillonite sheets, and has successfully revealed unforeseen structural transformations of clay minerals upon relaxation under different normal stress conditions. In order to first achieve the correct coupled simulation of atomic structural change and MD cell deformation, parametric studies were made on the effects of the time step and the "imaginary" mass M of the MD cell on the model behavior. It is found that the time step essentially controls the convergence behavior of the system, while the "imaginary" mass M has large influences on the final equilibrated structure of the system. Results of the parametric study suggest that values of 1.0×10-17 sec for the time step and 1.0×105 for the "imaginary" mass M are appropriate for the simulation of 2:1 clay minerals using the current method. Simulation results reveal the strong correlations between the degrees of constraints imposed on the simulation cell (i.e., whether the cell size or shape change is allowed) and the final equilibrated crystal structure of clay minerals. It is found during the relaxation process that large shear distortions of clay minerals will occur if full allowance is given to the cell size and shape change, while large shear stress in the sheet plane will be retained if only the cell size change is allowed. These structural

  9. Influence of clay minerals on sorption and bioreduction of arsenic under anoxic conditions.

    Science.gov (United States)

    Ghorbanzadeh, Nasrin; Lakzian, Amir; Halajnia, Akram; Kabra, Akhil N; Kurade, Mayur B; Lee, Dae S; Jeon, Byong-Hun

    2015-12-01

    Adsorption of As(V) on various clay minerals including kaolinite (KGa-1), montmorillonite (SWy-1) and nontronites (NAU-1 and NAU-2), and subsequent bioreduction of sorbed As(V) to As(III) by bacterium Shewanella putrefaciens strain CN-32 were investigated. Nontronites showed relatively higher sorption capacity for As(V) primarily due to higher iron oxide content. Freundlich equation well described the sorption of As(V) on NAU-1, NAU-2 and SWy-1, while As(V) sorption isotherm with KGa-1 fitted well in the Langmuir model. The bacterium rapidly reduced 50% of dissolved As(V) to As(III) in 2 h, followed by its complete reduction (>ca. 98%) within 12 h. In contrast, sorption of As(V) to the mineral surfaces interferes with the activity of bacterium, resulting in low bioreduction of As(V) by 27% for 5 days of incubation. S. putrefaciens also promoted the reduction of Fe(III) present in the clay mineral to Fe(II). This study indicates that the sorption and subsequent bioreduction of As(V) on clay minerals can significantly influence the mobility of As(V) in subsurface environment.

  10. Diversity of clay minerals in soils of solonetzic complexes in the southeast of Western Siberia

    Science.gov (United States)

    Chizhikova, N. P.; Khitrov, N. B.

    2016-12-01

    Data on the mineralogical composition of clay in soils of solonetzic complexes of the Priobskoe Plateau and the Kulunda and Baraba lowlands have been generalized. The parent materials predominating in these regions have loamy and clayey textures and are characterized by the association of clay minerals represented by dioctahedral and trioctahedral mica-hydromica, chlorite, kaolinite, and a number of irregular interstratifications. They differ in the proportions between the major mineral phases and in the qualitative composition of the minerals. Mica-hydromica and chlorites with a small amount of smectitic phase predominate on the Priobskoe Plateau and in the Kulunda Lowland; in the Baraba Lowland, the portion of mica-smectite interstratifications is higher. An eluvial-illuvial distribution of clay fraction in solonetzes is accompanied by the acid-alkaline destruction and lessivage of clay minerals, including the smectitic phase in the superdispersed state. This results in the strong transformation of the mineralogical composition of the upper (suprasolonetzic) horizons and in the enrichment of the solonetzic horizons with the products of mineral destruction; superdispersed smectite; and undestroyed particles of hydromica, kaolinite, and chlorite from the suprasolonetzic horizons. A significant decrease in the content of smectitic phase in the surface solodic horizons of solonetzic complexes has different consequences in the studied regions. In the soils of the Priobskoe Plateau and Kulunda Lowland with a relatively low content (10-30%) of smectitic phase represented by chlorite-smectite interstratifications, this phase virtually disappears from the soils (there are only rare cases of its preservation). In the soils of the Baraba Lowland developed from the parent materials with the high content (30-50%) of smectitic phase represented by mica-smectite interstratifications, the similar decrease (by 10-20%) in the content of smectitic phase does not result in its

  11. Subsurface water and clay mineral formation during the early history of Mars.

    Science.gov (United States)

    Ehlmann, Bethany L; Mustard, John F; Murchie, Scott L; Bibring, Jean-Pierre; Meunier, Alain; Fraeman, Abigail A; Langevin, Yves

    2011-11-02

    Clay minerals, recently discovered to be widespread in Mars's Noachian terrains, indicate long-duration interaction between water and rock over 3.7 billion years ago. Analysis of how they formed should indicate what environmental conditions prevailed on early Mars. If clays formed near the surface by weathering, as is common on Earth, their presence would indicate past surface conditions warmer and wetter than at present. However, available data instead indicate substantial Martian clay formation by hydrothermal groundwater circulation and a Noachian rock record dominated by evidence of subsurface waters. Cold, arid conditions with only transient surface water may have characterized Mars's surface for over 4 billion years, since the early-Noachian period, and the longest-duration aqueous, potentially habitable environments may have been in the subsurface.

  12. Microbial metabolism mediates interactions between dissolved organic matter and clay minerals in streamwater

    Science.gov (United States)

    Hunter, W. R.; Battin, T. J.

    2016-08-01

    Sorption of organic molecules to mineral surfaces is an important control upon the aquatic carbon (C) cycle. Organo-mineral interactions are known to regulate the transport and burial of C within inland waters, yet the mechanisms that underlie these processes are poorly constrained. Streamwater contains a complex and dynamic mix of dissolved organic compounds that coexists with a range of organic and inorganic particles and microorganisms. To test how microbial metabolism and organo-mineral complexation alter amino acid and organic carbon fluxes we experimented with 13C-labelled amino acids and two common clay minerals (kaolinite and montmorillonite). The addition of 13C-labelled amino acids stimulated increased microbial activity. Amino acids were preferentially mineralized by the microbial community, concomitant with the leaching of other (non-labelled) dissolved organic molecules that were removed from solution by clay-mediated processes. We propose that microbial processes mediate the formation of organo-mineral particles in streamwater, with potential implications for the biochemical composition of organic matter transported through and buried within fluvial environments.

  13. Features of Clay Minerals in the YSDP102 Core on the Continental Shelf of the Southeast Yellow Sea

    Institute of Scientific and Technical Information of China (English)

    JIANG Xuejun; QU Gaosheng; LI Shaoquan

    2004-01-01

    Ninety-eight clay mineral samples from the YSDP102 core were analyzed by x-ray diffractometer to study the four clay minerals: illite, chlorite, kaolinite and smectite. Twenty-eight samples had been analyzed on the laser particle-size analyzer to reveal the particle features of the sediments. Distribution of the clay minerals and the particle characteristics in the YSDP102 core show that the core experienced three different depositional periods and formed three different sedimentary intervals due to different sediment sources and different depositional environments. Features of the clay minerals and the heavy minerals in the YSDP102 core indicate that coarse-grained sediments and fine-grained sediments result from different sources. The Yellow Sea Warm Current has greatly influenced the sedimentary framework of this region since the current's formation.

  14. Crystal structure control of aluminized clay minerals on the mobility of caesium in contaminated soil environments

    Science.gov (United States)

    Dzene, Liva; Ferrage, Eric; Viennet, Jean-Christophe; Tertre, Emmanuel; Hubert, Fabien

    2017-01-01

    Radioactive caesium pollution resulting from Fukushima Dai-ichi and Chernobyl nuclear plant accidents involves strong interactions between Cs+ and clays, especially vermiculite-type minerals. In acidic soil environments, such as in Fukushima area, vermiculite is subjected to weathering processes, resulting in aluminization. The crystal structure of aluminized clays and its implications for Cs+ mobility in soils remain poorly understood due to the mixture of these minerals with other clays and organic matter. We performed acidic weathering of a vermiculite to mimic the aluminization process in soils. Combination of structure analysis and Cs+ extractability measurements show that the increase of aluminization is accompanied by an increase in Cs+ mobility. Crystal structure model for aluminized vermiculite is based on the interstratification of unaltered vermiculite layers and aluminized layers within the same particle. Cs+ in vermiculite layers is poorly mobile, while the extractability of Cs+ is greatly enhanced in aluminized layers. The overall reactivity of the weathered clay (cation exchange capacity, Cs+ mobility) is then governed by the relative abundance of the two types of layers. The proposed layer model for aluminized vermiculite with two coexisting populations of caesium is of prime importance for predicting the fate of caesium in contaminated soil environments. PMID:28233805

  15. Crystal structure control of aluminized clay minerals on the mobility of caesium in contaminated soil environments

    Science.gov (United States)

    Dzene, Liva; Ferrage, Eric; Viennet, Jean-Christophe; Tertre, Emmanuel; Hubert, Fabien

    2017-02-01

    Radioactive caesium pollution resulting from Fukushima Dai-ichi and Chernobyl nuclear plant accidents involves strong interactions between Cs+ and clays, especially vermiculite-type minerals. In acidic soil environments, such as in Fukushima area, vermiculite is subjected to weathering processes, resulting in aluminization. The crystal structure of aluminized clays and its implications for Cs+ mobility in soils remain poorly understood due to the mixture of these minerals with other clays and organic matter. We performed acidic weathering of a vermiculite to mimic the aluminization process in soils. Combination of structure analysis and Cs+ extractability measurements show that the increase of aluminization is accompanied by an increase in Cs+ mobility. Crystal structure model for aluminized vermiculite is based on the interstratification of unaltered vermiculite layers and aluminized layers within the same particle. Cs+ in vermiculite layers is poorly mobile, while the extractability of Cs+ is greatly enhanced in aluminized layers. The overall reactivity of the weathered clay (cation exchange capacity, Cs+ mobility) is then governed by the relative abundance of the two types of layers. The proposed layer model for aluminized vermiculite with two coexisting populations of caesium is of prime importance for predicting the fate of caesium in contaminated soil environments.

  16. Spectral stratigraphy and clay minerals analysis in parts of Hellas Planitia, Mars

    OpenAIRE

    Das, I. C.; J. Joseph; Subramanian, S. K.; V. K. Dadhwal

    2014-01-01

    Absorption features that occur in reflectance spectra are a sensitive indicator of mineralogy and chemical composition for a wide variety of materials. The investigation of the mineralogy and chemical composition of surfaces give information about the origin and evolution of planetary bodies. On Mars, the processes of formation of different types of clay minerals result from different types of wet conditions viz. hydrothermalism, subsurface/groundwater weathering, surface alteration ...

  17. METODOLOGY FOR LATERÍTICS CU-BEARING CLAY MINERALS CHARACTERIZATION

    Directory of Open Access Journals (Sweden)

    Eliana Satiko Mano

    2015-12-01

    This study describes an optimized methodology to characterize a Cu-lateritic ore, mainly composed of Cu-bearing clay minerals. Cations saturations and particle sizes separation, combined with X-ray diffraction, mid infrared spectroscopy and scanning electron microscopy allow concluding that this Cu-lateritic ore is mainly composed of smectites, micas and kaolinite; furthermore, the copper is especially associated to mica and secondarily to smectite.

  18. Importance of Tetrahedral Iron during Microbial Reduction of Clay Mineral NAu-2

    Science.gov (United States)

    Shi, B.; Wu, L.; Liu, K.; Smeaton, C. M.; Li, W.; Beard, B. L.; Johnson, C.; Roden, E. E.; Van Cappellen, P.

    2015-12-01

    Transformations between Fe(II) and Fe(III) in ferruginous clay minerals significantly impact the physicochemical properties of soils and sediments, such as the ion exchange capacity and redox potential. An increasing number of studies have focused on clay minerals that undergo redox changes, however, none have so far addressed Fe isotope fractionation during these processes. In this study, Fe isotope fractionations were determined during microbial reduction of Fe(III) in nontronite NAu-2 with different concentrations of lactate. No secondary Fe-bearing minerals, including Fe oxides, were detected by SEM in over 100 days of incubation, suggesting that the measured fractionations only reflected the net isotope effect associated with the clay minerals. The initial reduction likely started from edge sites, and the reductive dissolution released aqueous Fe(II). Basal plane sorbed Fe(II) was detectable after the extent of Fe reduction exceeded 5% and extensive electron transfer and isotope exchange had occurred between basal plane sorbed Fe(II) and structural Fe(III). With lower concentrations of the lactate(40 mM), the maximum Fe isotope fractionation was larger (∆56Febasal Fe(II)-structure Fe(III)= -4.37‰), consistent with greater adsorption than in systems with more lactate. After the Fe in reactive sites was all reduced, isotope exchange between Fe(II) and structural Fe(III) was inhibited due to blockage of electron transfer pathways by the collapse of the clay layers. The results agree with another study in our group on microbial reduction of NAu-1, despite both the smaller extent of reduction (~10% vs. 22% max bioreduction for NAu-1 and NAu-2, respectively) and smaller isotope fractionation factor than for NAu-2. We speculate that tetrahedral Fe in NAu-2 may have accelerated the electron transfer between Fe atoms, thus inducing a higher extent of reduction and a larger Fe isotope fractionation compared to NAu-1.

  19. Paleoenvironmental Implications of Clay Minerals at Yellowknife Bay, Gale Crater, Mars

    Science.gov (United States)

    Bristow, Thomas F.; Blake, David F.

    2014-01-01

    The Mars Science Laboratory (MSL) Rover, Curiosity spent approx 150 sols at Yellowknife Bay (YKB) studying a section of fluvio-lacustrine sedimentary rocks (with potential indications of volcanic influence), informally known as the Yellowknife Bay formation. YKB lies in a distal region of the Peace Vallis alluvial fan, which extends from the northern rim of Gale Crater toward the dune field at the base of Mt Sharp. Sedimentological and stratigraphic observations are consistent with the Yellowknife Bay formation being part of a distal fan deposit, which could be as young as middle Hesperian to even early Amazonian in age (approx. 3.5 to 2.5 Ga). The Yellowknife Bay formation hosts a unit of mudstone called the Sheepbed member. Curiosity obtained powdered rock samples from two drill holes in the Sheepbed Member, named John Klein and Cumberland, and delivered them to instruments in Curiosity. Data from CheMin, a combined X-ray diffraction (XRD)/X-ray fluorescence instrument (XRF), has allowed detailed mineralogical analysis of mudstone powders revealing a clay mineral component of approx. 20 wt.% in each sample. The clay minerals are important indicators of paleoenvironmental conditions and sensitive recorders of post-depositional alteration processes. The XRD pattern of John Klein reveals a 02l band consistent with a trioctahedral phyllosilicate. A broad peak at approx. 10A with a slight inflexion at approx. 12A indicates the presence of 2:1 type clay minerals in the John Klein sample. The trioctahedral nature of the clay minerals, breadth of the basal reflection, and presence of a minor component with larger basal spacing suggests that John Klein contains a trioctahedral smectite (probably saponite), whose interlayer is largely collapsed because of the low-humidity conditions. The XRD patterns show no evidence of corrensite (mixed-layer chlorite/smectite) or chlorite, which are typical diagenetic products of trioctahedral smectites when subjected to burial and

  20. Relationship between heavy metal contents and clay mineral properties in surface sediments: Implications for metal pollution assessment

    Science.gov (United States)

    Chen, Yueh-Min; Gao, Jin-bo; Yuan, Yong-Qiang; Ma, Jun; Yu, Shen

    2016-08-01

    Clay minerals in surface sediments can affect the adsorption of heavy metals. However, few historical studies have focused on the influence of fine clay mineral characteristics on metal sorption. Since the reactions between heavy metals and fine clay minerals in sediments remain obscure, this study investigates the influence of fine clay mineral characteristics on metal sorption in a typical urbanizing small watershed. Clay minerals, including nanoparticles with various size fractions ranging from 1000 to 2000 (clay), 450-1000 (fine clay), and 220-450 (very fine clay) nm were used to demonstrate their transformation from well crystalline to poorly crystalline. The nanoparticles were collected and evaluated by determination of their surface area, X-ray diffraction, scanning electron microscopy (SEM) and chemical analyses. The relationship between metal content and properties of the surface sediments was also revealed by canonical correlation analysis. With smaller particle sizes, nanoparticles (very fine clay) were observed to be poorly crystalline, possibly indicating few repetitions of unit cells as a result of preferential structural disruption of other crystal planes caused by pressure-induced phase transition in the fine-size fractions. The first canonical matrix (M) variables of metal contents can be predicted by both surface area and pore volume, followed by kaolinite and illite contents. On the other hand, the category of metal, i.e., Cu, Cr, Zn, or Pb, was significantly correlated with the first 'M' canonical variables. The data obtained in the present study are of fundamental significance in advancing our understanding of the reactions between heavy metals and fine clay minerals in the terrestrial ecosystem.

  1. Significance of saturation index of certain clay minerals in shallow coastal groundwater, in and around Kalpakkam, Tamil Nadu, India

    Indian Academy of Sciences (India)

    S Chidambaram; U Karmegam; P Sasidhar; M V Prasanna; R Manivannan; S Arunachalam; S Manikandan; P Anandhan

    2011-10-01

    The saturation index of clay minerals like Gibbsite, Kaolinite, Illite, Montmorillonite and Chlorite in groundwater were studied in detail by collecting 29 groundwater samples from the shallow coastal aquifers in and around Kalpakkam. The samples collected were analysed for major cations, anions and trace elements by using standard procedures. The study reveals that pH has a significant role in the saturation index (SI) of minerals. It also shows that the relationship of electrical conductivity to the SI of these minerals is not significant than that of the ionic strength, log pCO2 values, and alumina silica ratio have significant relation to the SI of these clay minerals. The SI of these clay minerals was spatially distributed to identify the areas of higher SI. Silica has good correlation to SI of Kaolinite, Gibbsite and Montmorillonite and Al has good correlation to SI of all the minerals except to that of Chlorite.

  2. Mineral carbonation of gaseous carbon dioxide using a clay-hosted cation exchange reaction.

    Science.gov (United States)

    Kang, Il-Mo; Roh, Ki-Min

    2013-01-01

    The mineral carbonation method is still a challenge in practical application owing to: (1) slow reaction kinetics, (2) high reaction temperature, and (3) continuous mineral consumption. These constraints stem from the mode of supplying alkaline earth metals through mineral acidification and dissolution. Here, we attempt to mineralize gaseous carbon dioxide into calcium carbonate, using a cation exchange reaction of vermiculite (a species of expandable clay minerals). The mineralization is operated by draining NaCI solution through vermiculite powders and continuously dropping into the pool of NaOH solution with CO2 gas injected. The mineralization temperature is regulated here at 293 and 333 K for 15 min. As a result of characterization, using an X-ray powder diffractometer and a scanning electron microscopy, two types of pure CaCO3 polymorphs (vaterite and calcite) are identified as main reaction products. Their abundance and morphology are heavily dependent on the mineralization temperature. Noticeably, spindle-shaped vaterite, which is quite different from a typical vaterite morphology (polycrystalline spherulite), forms predominantly at 333 K (approximately 98 wt%).

  3. Clay minerals as palaeomonsoon proxies: Evaluation and relevance to the late Quaternary records from SE Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Thamban, M.; Rao, V.P.

    as palaeoclimatic proxies are evaluated and discussed. Systematic investigations using several sediment cores from the SE Arabian Sea reveal that despite the influence of several complicating factors, variations in clay mineral composition during the late Quaternary...

  4. [Effect of treatments of hydrogen peroxide and sodium dithionite-citrate-bicarbonate on clay minerals of red earth sediments].

    Science.gov (United States)

    Li, Rong-Biao; Hong, Han-Lie; Yin, Ke; Wang, Chao-Wen; Gao, Wen-Peng; Han, Wen; Wu, Qing-Feng

    2013-04-01

    As classical procedures for pretreatment of soil sediments, hydrogen peroxide (H2O2) and sodium dithionite-citrate-bicarbonate (DCB) treatment methods are very important in removing the organic matter and iron oxides acting as cementing agents in the soils. However, both of these methods have less been focused on the effect on the clay minerals when separating. Here, we report the comparable methods between H2O2 and DCB to reveal their effect on clay minerals in red earth sediments using X-ray diffraction (XRD). The XRD results suggested that mineral particles can be totally decentralized by either H2O2 or DCB method in the soils and high purity clay minerals can be obtained by separating quartz and other impurities from clay minerals effectively. However, the XRD data were distorted by the DCB treatment owning to the cation exchange between Na+ and interlayer cation. On the contrary, the authentic data can be obtained by H2O2 treatment. Therefore, the H2O2 treatment seems to be a more appropriate method to obtain authentic information of clay mineralogy when separating of clay minerals from red earth sediments.

  5. Impact of clay mineral on air oxidation of PAH-contaminated soils.

    Science.gov (United States)

    Biache, Coralie; Kouadio, Olivier; Lorgeoux, Catherine; Faure, Pierre

    2014-09-01

    This work investigated the impact of a clay mineral (bentonite) on the air oxidation of the solvent extractable organic matters (EOMs) and the PAHs from contaminated soils. EOMs were isolated from two coking plant soils and mixed with silica sand or bentonite. These samples, as well as raw soils and bentonite/soil mixtures, were oxidized in air at 60 and 100 °C for 160 days. Mineralization was followed by measuring the CO2 produced over the experiments. EOM, polycyclic aromatic compound (PAC), including PAH, contents were also determined. Oxidation led to a decrease in EOM contents and PAH concentrations, these diminutions were enhanced by the presence of bentonite. Transfer of carbon from EOM to insoluble organic matter pointed out a condensation phenomenon leading to a stabilization of the contamination. Higher mineralization rates, observed during the oxidation of the soil/bentonite mixtures, seem to indicate that this clay mineral had a positive influence on the transformation of PAC into CO2.

  6. Climatic control on clay mineral formation: Evidence from weathering profiles developed on either side of the Western Ghats

    Indian Academy of Sciences (India)

    R Deepthy; S Balakrishnan

    2005-10-01

    Many physico-chemical variables like rock-type,climate,topography and exposure age affect weathering environments.In the present study,an attempt is made to understand how the nature of clay minerals formed due to weathering differs in tropical regions receiving high and low rainfall. Clay mineralogy of weathering pro files in west coast of India,which receives about 3 m rainfall through two monsoons and those from the inland rain-shadow zones (> 200 cm rainfall)are studied using X-ray diffraction technique.In the west coast,1:1 clays (kaolinite)and Fe –Al oxides (gibb-site/goethite)are dominant clay minerals in the weathering pro files while 2:1 clay minerals are absent or found only in trace amounts.Weathering pro files in the rain shadow region have more complex clay mineralogy and are dominated by 2:1 clays and kaolinite.Fe –Al oxides are either less or absent in clay fraction.The kaolinite –smectite interstrati fied mineral in Banasandra pro files are formed due to transformation of smectites to kaolinite,which is indicative of a humid paleo-climate. In tropical regions receiving high rainfall the clay mineral assemblage remains the same irrespective of the parent rock type.Rainfall and availability of water apart from temperature, are the most important factors that determine kinetics of chemical weathering.Mineral alteration reactions proceed through different pathways in water rich and water poor environments.

  7. Transmission X-ray Microscopy—A New Tool in Clay Mineral Floccules Characterization

    Directory of Open Access Journals (Sweden)

    Ray L. Frost

    2012-10-01

    Full Text Available Effective flocculation and dewatering of mineral processing streams containing clays are microstructure dependent in clay-water systems. Initial clay flocculation is crucial in the design and for the development of a new methodology of gas exploitation. Microstructural engineering of clay aggregates using covalent cations and Keggin macromolecules have been monitored using the new state of the art Transmission X-ray Microscope (TXM with 60 nm tomography resolution installed in a Taiwanese synchrotron. The 3-D reconstructions from TXM images show complex aggregation structures in montmorillonite aqueous suspensions after treatment with Na+, Ca2+ and Al13 Keggin macromolecules. Na-montmorillonite displays elongated, parallel, well-orientated and closed-void cellular networks, 0.5–3 µm in diameter. After treatment by covalent cations, the coagulated structure displays much smaller, randomly orientated and openly connected cells, 300–600 nm in diameter. The average distances measured between montmorillonite sheets was around 450 nm, which is less than half of the cell dimension measured in Na-montmorillonite. The most dramatic structural changes were observed after treatment by Al13 Keggin; aggregates then became arranged in compacted domains of a 300 nm average diameter composed of thick face-to-face oriented sheets, which forms porous aggregates with larger intra-aggregate open and connected voids.

  8. Comparison of revegetation techniques on mineral clay soil: analysis of quantitative response of vegetation cover

    Directory of Open Access Journals (Sweden)

    Enrico Muzzi

    2016-08-01

    Full Text Available Revegetation of mineral-clay soils is a notably complex ecological and technically challenging undertaking that depends on substrate profile and local micro-environmental conditions, factors making it a particularly long procedure as well. This study compared and assessed the medium-term effectiveness of four treatments employed to promote stable pedogenesis and herbaceous recolonisation of abandoned clay quarries in the Apennine foothills of northern Italy’s Emilia- Romagna region. The treatments included: slow-release N organic fertiliser, phosphate fertiliser, organic amendment and topsoil [the soil top layer (0-0.2 m of a local natural meadow]. The state of the vegetative cover was monitored monthly from 1994 through 2004, until problems of slope stability at the site compromised the integrity of the trial plots. Significant effects were achieved by the recycled topsoil through 8 years and by organic amendment through 6 years; the effects of slow-release nitrogen were notably limited over time and phosphorous delivered a medium-term response but of notable year-toyear swings. No interactions among factors emerged in the mediumterm. After 11 years, treatments did not induce effects statistical appreciable. Our results suggest that the tested agronomic strategies on mineral clay soil did not trigger, in the medium-term, secondary succession processes able to potentially alter the spontaneous revegetation course.

  9. Bio-Mobilization of Potassium from Clay Minerals: I. By Ectomycorrhizas

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A pot experiment was carried out to investigate effect of ectomycorrhizal fungi on eucalyptus growth and K bio-mobilization from soils and clay minerals. In the experiment, sands mixed with soil, KCl-saturated vermiculate and mica, respectively, were used to nurse eucalyptus seedlings which were nonectomycorrhized or ectomycorrhized by an ectomycorrhizal fungus Pisolithus tinctorius strain XC1 (Pt XC1) isolated from a forest soil from Xichang, Sichuan Province, China, and a worldwide well-known ectomycorrhizal fungus Pisolithus tinctorius strain 2 144 (Pt 2 144) obtained in Australia. More depletion of HCl-soluble K by mycorrhizas from the soil and minerals than nonmycorrhizas suggested that mycorrhizas had a great ability to mobilize K present in the interlayer and feldspar. Mycorrhizal seedlings depressed greatly K digested with HF-HClO4 from substrates after consecutive extractions of soils and minerals by water, ammonium acetate and boiling HCl, while nonmycorrhizal seedlings reduced it little if any, showing that the mycorrhizal seedlings could mobilize and then utilize the structural K in mineral lattice. Ectomycorrhizal fungi played a very important role not only in promoting the growth of eucalyptus seedlings but also in mobilizing K in soils and minerals. The infection of Pt XC1 led to a better growth of eucalyptus seedlings and more K accumulation in the seedlings than that of Pt 2 144. The large differences in K accumulation by the seedlings might be due to different abilities of the two ectomycorrhizal fungi to mobilize K in interlayer and lattice pools in the clay minerals.

  10. Removal of phosphate ions from aqueous solution using Tunisian clays minerals and synthetic zeolite

    Institute of Scientific and Technical Information of China (English)

    Noureddine Hamdi; Ezzeddine Srasra

    2012-01-01

    Phosphate ions are usually considered to be responsible for the algal bloom in receiving water bodies and aesthetic problems in water.From the environmental point of view,the management of such contaminant and valuable resource is very important.The present work deals with the removal of phosphate ions from aqueous solutions using kaolinitic and smectic clay minerals and synthetic zeolite as adsorbent.The pH effect and adsorption kinetic were studied.It was found that phosphate could be efficiently removed at acidic pH (between 4 and 6) and the second order model of kinetics is more adopted for all samples.The isotherms of adsorption of phosphate ions by the two clays and the zeolite samples show that the zeolite has the highest rate of uptake (52.9 mg P/g).Equilibrium data were well fitted with Langmuir and Freundlich isotherm.

  11. Molecular simulation of carbon dioxide, brine, and clay mineral interactions and determination of contact angles.

    Science.gov (United States)

    Tenney, Craig M; Cygan, Randall T

    2014-01-01

    Capture and subsequent geologic storage of CO2 in deep brine reservoirs plays a significant role in plans to reduce atmospheric carbon emission and resulting global climate change. The interaction of CO2 and brine species with mineral surfaces controls the ultimate fate of injected CO2 at the nanoscale via geochemistry, at the pore-scale via capillary trapping, and at the field-scale via relative permeability. We used large-scale molecular dynamics simulations to study the behavior of supercritical CO2 and aqueous fluids on both the hydrophilic and hydrophobic basal surfaces of kaolinite, a common clay mineral. In the presence of a bulk aqueous phase, supercritical CO2 forms a nonwetting droplet above the hydrophilic surface of kaolinite. This CO2 droplet is separated from the mineral surface by distinct layers of water, which prevent the CO2 droplet from interacting directly with the mineral surface. Conversely, both CO2 and H2O molecules interact directly with the hydrophobic surface of kaolinite. In the presence of bulk supercritical CO2, nonwetting aqueous droplets interact with the hydrophobic surface of kaolinite via a mixture of adsorbed CO2 and H2O molecules. Because nucleation and precipitation of minerals should depend strongly on the local distribution of CO2, H2O, and ion species, these nanoscale surface interactions are expected to influence long-term mineralization of injected carbon dioxide.

  12. Evidence for microbial liberation of structurally-coordinated iron in clay minerals as a nutrient source in the world ocean

    Science.gov (United States)

    Metcalfe, K. S.; Gaines, R. R.; Trang, J.; Scott, S.; Crane, E. J.; Lackey, J.; Prokopenko, M. G.; Berelson, W.

    2012-12-01

    Clay minerals are the most abundant materials found at the surface of earth and they are the primary constituents of marine sediments. Iron, a limiting nutrient in many marine settings, is a common constituent of clay minerals. Recent in vitro experimental evidence has shown that lab cultures of Fe-reducing bacteria are able to utilize structurally-bound Fe from the crystal lattice of nontronite, an uncommon and particularly Fe-rich (> 12 wt.%) smectitie. Reduction of structurally-coordinated Fe results in both the liberation of Fe(II) to solution, where it is available for other biotic processes, as well as the transformation of smectite to illite. However, it remains unclear: 1. whether Fe-reducers are able to access structurally coordinated Fe found at low wt.% in common clay minerals; and 2. if naturally occuring populations of Fe-reducers are able to reduce structurally coordinated Fe as are some lab strains. In order to address these questions, we conducted in vitro experiments using a suite of sixteen clay minerals with low (0.8 wt.%) to high (13.9 wt.%) Fe concentrations. Clays were treated with Na-dithionite solution to remove surface-bound Fe, isolating for study Fe sourced from within the clay crystal lattice. Experimental evidence clearly indicates that, under in vitro conditions, Fe(III) bound in common clay minerals is available for reduction by the lab strain Shewanella oneidensis MR-1 as well as by naturally-occuring consortia of Fe-reducers cultured from the San Pedro and Santa Monica Basins. Our findings suggest that common clay minerals may represent a large and previously unrecognized pool of bioavailable Fe in the world ocean that contributes significantly to biogeochemical cycling of Fe and C.

  13. Adsorption ability of rare earth elements on clay minerals and its practical performance

    Institute of Scientific and Technical Information of China (English)

    肖燕飞; 龙志奇; 黄莉; 冯宗玉; 王良士

    2016-01-01

    The adsorption behaviors of rare earth elements on clay minerals would have great influence on the mineralization process and the leaching process of the ion-adsorption type rare earths ore. In this work, the adsorption thermodynamics of REEs on kaolin were investigated thoroughly and systematically. The experimental results showed that the adsorption characteristics of La, Nd, Y on kaolin did fit well with the Langmuir isotherm model and their saturated adsorption capacities were 1.731, 1.587 and 0.971 mg/g, re-spectively. The free energy change (ΔG) values were –16.91 kJ/mol (La), –16.05 kJ/mol (Nd) and –15.58 kJ/mol (Y), respectively. The negative values ofΔG demonstrated that the adsorption of rare earth on kaolin was a spontaneously physisorption process. The deposit characteristic of the volcanic ion-adsorption type rare earths ore and the behavior of the rare earth in the column leaching process were also developed here. With the increase of the ore body depth, the distribution of the LREEs decreased and the HREEs increased. And the slight differences in the adsorption ability of REEs on clay minerals led to the fractionation effect in the column leaching process. These developed more evidences and better understanding of metallogenic regularity, and provided a theoretical ba-sis and scientific approach to separation of the HREEs and LREEs in the leaching process.

  14. [Research on characteristics of soil clay mineral evolution in paddy field and dry land by XRD spectrum].

    Science.gov (United States)

    Zhang, Zhi-dan; Li, Qiao; Luo, Xiang-li; Jiang, Hai-chao; Zheng, Qing-fu; Zhao, Lan-po; Wang, Ji-hong

    2014-08-01

    The present paper took the typical saline-alkali soil in Jilin province as study object, and determinated the soil clay mineral composition characteristics of soil in paddy field and dry land. Then XRD spectrum was used to analyze the evolutionary mechanism of clay mineral in the two kinds of soil. The results showed that the physical and chemical properties of soil in paddy field were better than those in dry land, and paddy field would promote the weathering of mineral particles in saline-alkali soil and enhance the silt content. Paddy field soil showed a strong potassium-removal process, with a higher degree of clay mineral hydration and lower degree of illite crystallinity. Analysis of XRD spectrum showed that the clay mineral composition was similar in two kinds of soil, while the intensity and position of diffraction peak showed difference. The evolution process of clay mineral in dry land was S/I mixture-->vermiculite, while in paddy field it was S/I mixture-->vermiculite-->kaolinite. One kind of hydroxylated 'chlorite' mineral would appear in saline-alkali soil in long-term cultivated paddy field. Taking into account that the physical and chemical properties of soil in paddy field were better then those in dry land, we could know that paddy field could help much improve soil structure, cultivate high-fertility soil and improve saline-alkali soil. This paper used XRD spectrum to determine the characteristics of clay minerals comprehensively, and analyzed two'kinds of land use comparatively, and was a new perspective of soil minerals study.

  15. Quantitative XRD HW-IR plot for clay mineral domain size and lattice strain analyses

    Science.gov (United States)

    Wang, H. J.; Chen, D. Z.; Zhou, J.; Chen, T.; Wang, H.; Zhang, Z. Q.

    2003-04-01

    Based on integral-breadth method, the one of three basic XRD methods (Klug &Alexander, 1974), authors (2000) proposed a qualitative half width (HW)-intensity ratio (IR) plot for clay mineral domain size and lattice strain analyses. In this study, the quantitative HW-IR plot is further developed on the basis of i) the curve relation between the Voigt function and the Pearson VII function; ii) the relationship between the Kübler index and the Weaver index. By numerical simulating, it is derived a curve relation between shape indexes k of the Voigt function and u of the Pearson VII function. With this curve relation, k and u can be converted each other in an accuracy of ten thousandth and therefore the domain size and the lattice strain contributions can be precisely separated from an XRD peak according to Langford's (1978) formula. For micaceous minerals, the HW-IR plot requires only a pair of values of the Kübler index and the Weaver index from 1nm reflection. For other clay minerals, the plot needs a pair of values of the (00l) peak's half width and intensity ratio IR. IR is a ratio of peak maximum to the intensity at the position of maximum minus 0.422oΔ2Θ in CuKα radiation. This quantitative plot renders a mean dimension of clay particles perpendicular to the reflection plane (00l) and an approximate upper limit strain normal to d001. The accuracy for domain size analysis reaches one tenth of nanometre and that for the lattice strain analysis is in ten thousandth respectively. This plot method can be widely used with any digital X-ray diffractometer, whose XRD data can be converted into text format. Excel 5.0 or latter versions in both English and Chinese can well support the HW-IR plot. This study was supported by NNSFC (Grant No 40272022)

  16. Potential Sites for Ice Nucleation on Aluminosilicate Clay Minerals and Related Materials.

    Science.gov (United States)

    Freedman, Miriam Arak

    2015-10-01

    Few aerosol particles in clouds nucleate the formation of ice. The surface sites available for nucleus formation, which can include surface defects and functional groups, determine in part the activity of an aerosol particle toward ice formation. Although ice nucleation on particles has been widely studied, exploration of the specific sites at which the initial germ forms has been limited, but is important for predicting the microphysical properties of clouds, which impact climate. This Perspective focuses on what is currently known about surface sites for ice nucleation on aluminosilicate clay minerals, which are commonly found in ice residuals, as well as related materials.

  17. Development and evaluation of a new sorption model for organic cations in soil: contributions from organic matter and clay minerals.

    Science.gov (United States)

    Droge, Steven T J; Goss, Kai-Uwe

    2013-12-17

    This study evaluates a newly proposed cation-exchange model that defines the sorption of organic cations to soil as a summed contribution of sorption to organic matter (OM) and sorption to phyllosilicate clay minerals. Sorption to OM is normalized to the fraction organic carbon (fOC), and sorption to clay is normalized to the estimated cation-exchange capacity attributed to clay minerals (CECCLAY). Sorption affinity is specified to a fixed medium composition, with correction factors for other electrolyte concentrations. The model applies measured sorption coefficients to one reference OM material and one clay mineral. If measured values are absent, then empirical relationships are available on the basis of molecular volume and amine type in combination with corrective increments for specific polar moieties. The model is tested using new sorption data generated at pH 6 for two Eurosoils, one enriched in clay and the other, OM, using 29 strong bases (pKa > 8). Using experimental data on reference materials for all tested compounds, model predictions for the two soils differed on average by only -0.1 ± 0.4 log units from measured sorption affinities. Within the chemical applicability domain, the model can also be applied successfully to various reported soil sorption data for organic cations. Particularly for clayish soils, the model shows that sorption of organic cations to clay minerals accounts for more than 90% of the overall affinity.

  18. The First X-ray Diffraction Patterns of Clay Minerals from Gale Crater

    Science.gov (United States)

    Bristow, Thomas; Blake, David; Bish, David L.; Vaniman, David; Ming, Douglas W.; Morris, Richard V.; Chipera, Steve; Rampe, Elizabeth B.; Farmer, Jack, D.; Treiman, Allan H; Downs, Robert; Morrison, Shaunna; Achilles, Cherie; DesMarais, David J.; Crisp, Joy A.; Sarrazin, Philippe; Morookian, John Michael; Grotzinger. John P.

    2013-01-01

    The Mars Science Laboratory (MSL) Rover, Curiosity spent approx 150 sols at Yellowknife Bay (YKB) studying a section of fluvio-lacustrine sedimentary rocks (with potential indications of volcanic influence), informally known as the Yellowknife Bay formation. YKB lies in a distal region of the Peace Vallis alluvial fan, which extends from the northern rim of Gale Crater toward the dune field at the base of Mt Sharp. Sedimentological and stratigraphic observations are consistent with the Yellowknife Bay formation being part of a distal fan deposit, which could be as young as middle Hesperian to even early Amazonian in age (approx 3.5 to 2.5 Ga). The Yellowknife Bay formation hosts a unit of mudstone called the Sheepbed member. Curiosity obtained powdered rock samples from two drill holes in the Sheepbed Member, named John Klein and Cumberland, and delivered them to instruments in Curiosity. Data from CheMin, a combined X-ray diffraction (XRD)/X-ray fluorescence instrument (XRF), has allowed detailed mineralogical analysis of mudstone powders revealing a clay mineral component of approx 20 wt.% in each sample. The clay minerals are important indicators of paleoenvironmental conditions and sensitive recorders of post-depositional alteration processes. The XRD pattern of John Klein reveals a 021 band consistent with a trioctahedral phyllosilicate. A broad peak at approx 10A with a slight inflexion at approx 12A indicates the presence of 2:1 type clay minerals in the John Klein sample. The trioctahedral nature of the clay minerals, breadth of the basal reflection, and presence of a minor component with larger basal spacing suggests that John Klein contains a trioctahedral smectite (probably saponite), whose interlayer is largely collapsed because of the low-humidity conditions. The XRD patterns show no evidence of corrensite (mixed-layer chlorite/smectite) or chlorite, which are typical diagenetic products of trioctahedral smectites when subjected to burial and heating

  19. Clay minerals and geochemistry of the bottom sediments in the northwestern East China Sea

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Clay minerals of 34 sediments collected from the northwestern continental shelf of the East China Sea have been determined by X-ray diffraction analysis. The clay mineral distribution is mainly controlled by the sediment source and the dominant circulation pattern. The predominant clay mineral in our study area is illite comprising more than 67% of the whole clay fraction. The highest concentration of illite (>68%) is found in the southeastern offshore parts beyond the reach of terrigenous input from the Jeju Island. It means that these illites are largely transported by the Kuroshio Current from the South China Sea (SCS). Smectite is highly concentrated in the northwest middle part and in the outer-shelf mud patch. It seems to be due to the high supply of smectite transported from China where fine-grained sediments are discharged from modern and ancient Huanghe (Yellow) River. The relatively high abundant kaolinite is likely derived from the Changjiang (Yangtze) River via the Taiwan Warm Current. In contrast,large amounts of chlorite and high chlorite/kaolinite ratios occur in the northwestern area, reflecting the transportation by the Yellow Sea Coastal Current from the southern Yellow Sea. The discrimination diagrams clearly show that the sediments in the northwestern East China Sea are ultimately sourced from Chinese rivers, especially from the Huanghe River, whereas the sediment in the northeast part might come from the Jeju Island. The muddy sediments of the Changjiang River's submerged delta have much lower 87Sr/86Sr ratios (0.7162-0.7180) than those of the Shandong Peninsular mud wedge (0.7216-0.7249),which are supposed to be originated from the Huanghe River, suggesting the distribution pattern of 87Sr/86Sr ratios as a new tracer to discriminate the provenance of shelf sediments in the study area. The 87Sr/86Sr ratios of the outer-shelf muddy sediments ranged from 0.7169 to 0.7216 in a wide range and was between those of the Huanghe River and Changjiang

  20. Effect of clay minerals and nanoparticles on chromium fractionation in soil contaminated with leather factory waste.

    Science.gov (United States)

    Taghipour, Marzieh; Jalali, Mohsen

    2015-10-30

    This study was conducted to investigate the effect of time, clay minerals and nanoparticles (NPs) on chromium (Cr) fractionation in a soil contaminated with leather factory waste (LFW). Soil was mixed with LFW, then, the contaminated soils were treated with clay minerals (bentonite and zeolite) and nanoparticles (MgO, TiO2 and ZnO) at 5% and 1%, respectively. The samples were incubated for 15-180 days at 25 °C and constant moisture. After incubation, Cr in control and treated soils was fractionated by the sequential extraction procedure. The distribution of various Cr fractions in control soil indicated that the greatest amounts of Cr were found in the residual fraction (RES) followed by the carbonate (CAR), organic matter (OM) and exchangeable (EXC) fractions. The addition of LFW in soils increased Cr concentration in all fractions. The higher proportion of EXC fraction in the soil treated with LFW indicates its higher potential of leaching and runoff transport. In all treated soils, the RES fraction was increased, while EXC and OM fractions were decreased during incubation. The results indicated that NPs are effective adsorbent for the removal of Cr ions from LFW treated soil, and they could be useful in reducing their environment risk.

  1. Removal of polycyclic aromatic hydrocarbons (PAHs) from inorganic clay mineral: Bentonite.

    Science.gov (United States)

    Karaca, Gizem; Baskaya, Hüseyin S; Tasdemir, Yücel

    2016-01-01

    There has been limited study of the removal of polycyclic aromatic hydrocarbons (PAHs) from inorganic clay minerals. Determining the amount of PAH removal is important in predicting their environmental fate. This study was carried out to the degradation and evaporation of PAHs from bentonite, which is an inorganic clay mineral. UV apparatus was designed specifically for the experiments. The impacts of temperature, UV, titanium dioxide (TiO2), and diethylamine (DEA) on PAH removal were determined. After 24 h, 75 and 44 % of ∑12 PAH in the bentonite were removed with and without UV rays, respectively. DEA was more effective as a photocatalyst than TiO2 during UV application. The ∑12 PAH removal ratio reached 88 % with the addition of DEA to the bentonite. It was concluded that PAHs were photodegraded at high ratios when the bentonite samples were exposed to UV radiation in the presence of a photocatalyst. At the end of all the PAH removal applications, higher evaporation ratios were obtained for 3-ring compounds than for heavier ones. More than 60 % of the amount of ∑12 PAH evaporated consisted of 3-ring compounds.

  2. Microorganism-induced weathering of clay minerals in a hydromorphic soil

    Science.gov (United States)

    Hong, Hanlie; Fang, Qian; Cheng, Liuling; Wang, Chaowen; Churchman, Gordon Jock

    2016-07-01

    In order to improve the understanding of factors influencing weathering in hydromorphic soils, the clay mineral and chemical compositions, iron (hydr)oxides, organic compounds, and Sr and Nd isotopic compositions, of hydromorphic soils on the banks of the Liangzi Lake, Hubei province, south China, were investigated. The B horizon in the lower profile exhibits a distinct net-like pattern, with abundant short white veins within the red-brown matrix. Their various 87Sr/86Sr and 143Nd/144Nd isotopic compositions showed only small variations of 0.7270-0.7235 and 0.51200-0.51204, respectively, consistent with the composition of Yangtze River sediments, indicating that the soils were all derived from alluvium from the catchment. The white veins contained notably more SiO2, Al2O3, TiO2, and mobile elements relative to the red-brown matrix, while they both showed similar values for the chemical index of alteration of 86.7 and 87.1, respectively, and displayed similar degrees of weathering. The clay minerals in A, AE, and E horizons of the soil profile were illite, kaolinite, and mixed-layer illite-smectite. These same three clay minerals comprised the white net-like veins in the soil B horizon, whereas only illite and kaolinite were observed in the red-brown matrix. Iron (hydr)oxides in A, AE, and E horizons of the soil profile were hematite and goethite, whereas in the red-brown matrix of the B horizon they were hematite, goethite, and ferrihydrite. Different organic compounds were observed for the white vein and the red-brown matrix in the soil B horizon: an 18:2 fatty acid biomarker for fungi in the net-like vein, but not in the red-brown matrix. Compared with the red-brown matrix, the white net-like vein also clearly contained more mono-unsaturated fatty acids, which are sometimes associated with bacteria that have the capacity to reduce Fe(III). Thus, migration of iron and the formation of the net-like veins involved the participation of biota during the hydromorphic

  3. Spectroscopic evidence for Fe(II)-Fe(III) electron transfer at clay mineral edge and basal sites.

    Science.gov (United States)

    Neumann, Anke; Olson, Tyler L; Scherer, Michelle M

    2013-07-02

    Despite the importance of Fe redox cycling in clay minerals, the mechanism and location of electron transfer remain unclear. More specifically, there is some controversy whether electron transfer can occur through both basal and edge surfaces. Here we used Mössbauer spectroscopy combined with selective chemical extractions to study electron transfer from Fe(II) sorbed to basal planes and edge OH-groups of clay mineral NAu-1. Fe(II) sorbed predominantly to basal planes at pH values below 6.0 and to edge OH-groups at pH value 7.5. Significant electron transfer occurred from edge OH-group bound Fe(II) at pH 7.5, whereas electron transfer from basal plane-sorbed Fe(II) to structural Fe(III) in clay mineral NAu-1 at pH 4.0 and 6.0 occurred but to a much lower extent than from edge-bound Fe(II). Mössbauer hyperfine parameters for Fe(II)-reacted NAu-1 at pH 7.5 were consistent with structural Fe(II), whereas values found at pH 4.0 and 6.0 were indicative of binding environments similar to basal plane-sorbed Fe(II). Reference experiments with Fe-free synthetic montmorillonite SYn-1 provided supporting evidence for the assignment of the hyperfine parameters to Fe(II) bound to basal planes and edge OH-groups. Our findings demonstrate that electron transfer to structural Fe in clay minerals can occur from Fe(II) sorbed to both basal planes and edge OH-groups. These findings require us to reassess the mechanisms of abiotic and microbial Fe reduction in clay minerals as well as the importance of Fe-bearing clay minerals as a renewable source of redox equivalents in subsurface environments.

  4. Soft X-ray spectromicroscopy study of mineral-organic matter associations in pasture soil clay fractions.

    Science.gov (United States)

    Chen, Chunmei; Dynes, James J; Wang, Jian; Karunakaran, Chithra; Sparks, Donald L

    2014-06-17

    There is a growing acceptance that associations with soil minerals may be the most important overarching stabilization mechanism for soil organic matter. However, direct investigation of organo-mineral associations has been hampered by a lack of methods that can simultaneously characterize organic matter (OM) and soil minerals. In this study, STXM-NEXAFS spectroscopy at the C 1s, Ca 2p, Fe 2p, Al 1s, and Si 1s edges was used to investigate C associations with Ca, Fe, Al, and Si species in soil clay fractions from an upland pasture hillslope. Bulk techniques including C and N NEXAFS, Fe K-edge EXAFS spectroscopy, and XRD were applied to provide additional information. Results demonstrated that C was associated with Ca, Fe, Al, and Si with no separate phase in soil clay particles. In soil clay particles, the pervasive C forms were aromatic C, carboxyl C, and polysaccharides with the relative abundance of carboxyl C and polysaccharides varying spatially at the submicrometer scale. Only limited regions in the soil clay particles had aliphatic C. Good C-Ca spatial correlations were found for soil clay particles with no CaCO3, suggesting a strong role of Ca in organo-mineral assemblage formation. Fe EXAFS showed that about 50% of the total Fe in soils was contained in Fe oxides, whereas Fe-bearing aluminosilicates (vermiculite and Illite) accounted for another 50%. Fe oxides in the soil were mainly crystalline goethite and hematite, with lesser amounts of poorly crystalline ferrihydrite. XRD revealed that soil clay aluminosilicates were hydroxy-interlayered vermiculite, Illite, and kaolinite. C showed similar correlation with Fe to Al and Si, implying a similar association of Fe oxides and aluminosilicates with organic matter in organo-mineral associations. These direct microscopic determinations can help improve understanding of organo-mineral interactions in soils.

  5. Clay mineral distribution in surface sediments of the South China Sea and its significance for in sediment sources and transport

    Institute of Scientific and Technical Information of China (English)

    刘建国; 陈木宏; 陈忠; 颜文

    2010-01-01

    Clay minerals of surface sediments in the South China Sea (SCS) are analyzed with X-ray diffraction, and their transport is explored with a grain size trend analysis (GSTA) model. Results show that clay mineral types in various sedimentary environments have different sediment sources and transport routes. Sediments in the northern SCS (north of 20°N) between the southwest of Taiwan Island and the outer mouth of the Pearl River have high contents of illite and chlorite, which are derived mainly from sediment...

  6. Terrestrial Analogs for Clay Minerals at Yellowknife Bay, Gale Crater, Mars

    Science.gov (United States)

    Treiman, Allan H; Morris, Richard V.; Bristow, Thomas; Ming, Douglas W.; Achillies, Cherie; Bish, David L.; Blake, David; Vaniman, David; Chipera, Steve

    2013-01-01

    the last three varieties may be contemporaneous. One sample shows agate (alpha- quartz) that was precipitated between the episodes of deposition of the fine-grained and coarse-grained 'griffithite.' 'Griffithite' is not unique as a possible terrestrial analog - some clay minerals from the Doushantou formation, China, have similar 02L diffraction bands, and many basalts contain smectites in vesicles and as replacements after olivine. Similar trioctahedral smectites occur also in the nakhlite martian meteorites - as veinlets and replacements of olivine. By understanding the formation of these terrestrial clays, we hope to constrain the nature and mechanism of formation of the Sheepbed clay mineral.

  7. Understanding the role of clay minerals in the chromium(VI) bioremoval by Pseudomonas aeruginosa CCTCC AB93066 under growth condition: microscopic, spectroscopic and kinetic analysis.

    Science.gov (United States)

    Kang, Chunxi; Wu, Pingxiao; Li, Yuewu; Ruan, Bo; Li, Liping; Tran, Lytuong; Zhu, Nengwu; Dang, Zhi

    2015-11-01

    Laboratory batch experiments were conducted to investigate the role of clay minerals, e.g., kaolinite and vermiculite, in microbial Cr(VI) reduction by Pseudomonas aeruginosa under growth condition in glucose-amended mediums as a method for treating Cr(VI)-contaminated subsurface environment such as soil. Our results indicated that glucose could acted as an essential electron donor, and clay minerals significantly enhanced microbial Cr(VI) reduction rates by improving the consumption rate of glucose and stimulating the growth and propagation of P. aeruginosa. Cr(VI) bioreduction by both free cells and clay minerals-amended cells followed the pseudo-first-order kinetic model, with the latter one fitting better. The mass balance analyses and X-ray photoelectron spectroscopy analysis found that Cr(VI) was reduced to Cr(III) and the adsorption of total chromium on clay minerals-bacteria complex was small, implying that Cr(VI) bioremoval was not mainly due to the adsorption of Cr(VI) onto cells or clay minerals or clay minerals-cells complex but mainly due to the Cr(VI) reduction capacity of P. aeruginosa under the experimental conditions studied (e.g., pH 7). Atomic force microscopy revealed that the addition of clay minerals (e.g. vermiculite) decreased the surface roughness of Cr(VI)-laden cells and changed the cell morphology and dimension. Fourier transform infrared spectroscopy revealed that organic matters such as aliphatic species and/or proteins played an important role in the combination of cells and clay minerals. Scanning electron microscopy confirmed the attachment of cells on the surface of clay minerals, indicating that clay minerals could provide a microenvironment to protect cells from Cr(VI) toxicity and serve as growth-supporting materials. These findings manifested the underlying influence of clay minerals on microbial reduction of Cr(VI) and gave an understanding of the interaction between pollutants, the environment and the biota.

  8. Influence of crop residues on trifluralin mineralization in a silty clay loam soil.

    Science.gov (United States)

    Farenhorst, Annemieke

    2007-01-01

    Trifluralin is typically applied onto crop residues (trash, stubble) at the soil surface, or onto the bare soil surface after the incorporation of crop residues into the soil. The objective of this study was to quantify the effect of the type and amount of crop residues in soil on trifluralin mineralization in a Wellwood silty clay loam soil. Leaves and stubble of Potato (Solanum tuberosum) (P); Canola (Brassica napus) (C), Wheat (Triticum aestivum) (W), Oats (Avena sativa), (O), and Alfalfa (Medicago sativa) (A) were added to soil microcosms at rates of 2%, 4%, 8% and 16% of the total soil weight (25 g). The type and amount of crop residues in soil had little influence on the trifluralin first-order mineralization rate constant, which ranged from 3.57E-03 day(-1) in soil with 16% A to 2.89E-02 day(-1) in soil with 8% W. The cumulative trifluralin mineralization at 113 days ranged from 1.15% in soil with 16% P to 3.21% in soil with 4% C, again demonstrating that the observed differences across the treatments are not of agronomic or environmental importance.

  9. Contact angles at the water-air interface of hydrocarbon-contaminated soils and clay minerals

    Science.gov (United States)

    Sofinskaya, O. A.; Kosterin, A. V.; Kosterina, E. A.

    2016-12-01

    Contact angles at the water-air interface have been measured for triturated preparations of clays and soils in order to assess changes in their hydrophobic properties under the effect of oil hydrocarbons. Tasks have been to determine the dynamics of contact angle under soil wetting conditions and to reveal the effect of chemical removal of organic matter from soils on the hydrophilicity of preparations. The potentialities of static and dynamic drop tests for assessing the hydrophilic-hydrophobic properties of soils have been estimated. Clays (kaolinite, gumbrine, and argillite) have been investigated, as well as plow horizons of soils from the Republic of Tatarstan: heavy loamy leached chernozem, medium loamy dark gray forest soil, and light loamy soddy-calcareous soil. The soils have been contaminated with raw oil and kerosene at rates of 0.1-3 wt %. In the uncontaminated and contaminated chernozem, capillary water capacity has been maintained for 250 days. The contact angles have been found to depend on the degree of dispersion of powdered preparation, the main type of clay minerals in the soil, the presence and amount of oxidation-resistant soil organic matter, and the soil-water contact time. Characteristic parameters of mathematical models for drop behavior on triturated preparations have been calculated. Contamination with hydrocarbons has resulted in a reliable increase in the contact angles of soil preparations. The hydrophobization of soil surface in chernozem is more active than in soils poorer in organic matter. The complete restoration of the hydrophilic properties of soils after hydrocarbon contamination is due to the oxidation of easily oxidizable organic matter at the low content of humus, or to wetting during several months in the absence of the mazut fraction.

  10. Clay minerals in surface sediments of the Pearl River drainage basin and their contribution to the South China Sea

    Institute of Scientific and Technical Information of China (English)

    LIU ZhiFei; Christophe COLIN; HUANG Wei; CHEN Zhong; Alain TRENTESAUX; CHEN JianFang

    2007-01-01

    Clay minerals have played a significant role in the study of the East Asian monsoon evolution in the South China Sea by being able to track oceanic current variations and to reveal contemporaneous paleoclimatic changes prevailing in continental source areas. As one of the most important rivers inputting terrigenous matters to the northern South China Sea, the Pearl River was not previously paid attention to from the viewpoint of clay mineralogy. This paper presents a detailed study on clay minerals in surface sediments collected from the Pearl River drainage basin (including all three main channels,various branches, and the Lingdingyang in the estuary) by using the X-ray diffraction (XRD) method.The results indicate that the clay mineral assemblage consists dominantly of kaolinite (35%-65%),lesser abundance of chlorite (20%-35%) and illite (12%-42%), and very scare smectite occurrences (generally <5%). Their respective distribution does not present any obvious difference throughout the Pearl River drainage basin. However, downstream the Pearl River to the northern South China Sea, the clay mineral assemblage varies significantly: kaolinite decreases gradually, smectite and illite increase gradually. Additionally, illite chemistry index steps down and illite crystallinity steps up. These variations indicate the contribution of major kaolinite, lesser illite and chlorite, and very scarce smectite to the northern South China Sea from the Pearl River drainage basin. The maximum contribution of clay minerals from the Pearl River is 72% to the northern margin and only 15% to the northern slope of the South China Sea. In both glacials and interglacials, kaolinite indicates that the ability of mechanical erosion occurred in the Pearl River drainage basin.

  11. Modern and late Quaternary clay mineral distribution in the area of the SE Mediterranean Sea

    Science.gov (United States)

    Hamann, Yvonne; Ehrmann, Werner; Schmiedl, Gerhard; Kuhnt, Tanja

    2009-05-01

    The present-day clay mineral distribution in the southeastern Levantine Sea and its borderlands reveals a complex pattern of different sources and distribution paths. Smectite dominates the suspended load of the Nile River and of rivers in the Near East. Illite sources are dust-bearing winds from the Sahara and southwestern Europe. Kaolinite is prevalent in rivers of the Sinai, in Egyptian wadis, and in Saharan dust. A high-resolution sediment core from the southeastern Levantine Sea spanning the last 27 ka shows that all these sources contributed during the late Quaternary and that the Nile River played a very important role in the supply of clay. Nile influence was reduced during the glacial period but was higher during the African Humid Period. In contrast to the sharp beginning and end of the African Humid Period recorded in West African records (15 and 5.5 ka), our data show a more transitional pattern and slightly lower Nile River discharge rates not starting until 4 ka. The similarity of the smectite concentrations with fluctuations in sea-surface temperatures of the tropical western Indian Ocean indicates a close relationship between the Indian Ocean climate system and the discharge of the Nile River.

  12. The Imprint of Atmospheric Evolution in the D/H of Hesperian Clay Minerals on Mars

    Science.gov (United States)

    Mahaffy, P. R.; Webster, C. R.; Stern, J. C.; Brunner, A. E.; Atreya, S. K.; Conrad, P. G.; Domagal-Goldman, S.; Eigenbrode, J. L.; Flesch, G. J.; Christensen, L. E.; Franz, H. B.; Glavin, D. P.; Jones, J. H.; McAdam, A. C.; Pavlov, A. A.; Trainer, M. G.; Williford, K. H.

    2014-01-01

    The deuterium-to-hydrogen (D/H) ratio in strongly bound water or hydroxyl groups in ancient Martian clays retains the imprint of the water of formation of these minerals. Curiosity's Sample Analysis at Mars (SAM) experiment measured thermally evolved water and hydrogen gas released between 550 degrees Centigrade and 950 degrees Centigrade from samples of Hesperian-era Gale crater smectite to determine this isotope ratio. The D/H value is 3.0 (plus or minus 0.2) times the ratio in standard mean ocean water. The D/H ratio in this approximately 3-billion-year-old mudstone, which is half that of the present Martian atmosphere but substantially higher than that expected in very early Mars, indicates an extended history of hydrogen escape and desiccation of the planet.

  13. The differences in clay minerals between the northern and southern Chelungpu fault, Taiwan

    Science.gov (United States)

    Hashimoto, Y.

    2004-12-01

    In 1999, we obtained a detailed data about motion of fault from the Taiwan Chi-Chi earthquake. The motion represents the high frequency of acceleration and small slip distance in southern part, and low frequency of acceleration and large slip distance in the northern part. Those differences in the fault motion between the southern and northern parts are coincidence with occurrences of deformation textures of rocks which were sampled by drilling of shallow parts (a few hundreds meter) of the fault in 2000. In the southern core, a relatively strong deformation structure is preserved in total, and gouge containing fragments of pseudotachylytes and ultracataclasites is observed at the Chi-Chi- earthquake fault, which indicates that the main deformation mechanisms for the southern part of the fault was brittle. On the other hands, in the northern part, sand layer with much amount of water is found at the Chi-Chi- earthquake fault zone, and no breakage of sand grain is observed, which suggests that the deformation mechanism for northern part is independent particulate flow. The purpose of this study is to reveal the differences in clay minerals between the southern and northern part of the Chi-Chi earthquake fault. And then, we discuss about rock-fluid interaction and frictional heating characterized in seismogenic fault system. We analyzed clay minerals by X-ray diffract meter (XRD) after classification of rock types such as sandstone, alteration of sandstone and mudstone, breccia, and gouge. 1.33 micron meter of grains are obtained. Oriented sample was made. XRD analysis was conducted under following condition; 35kV, 15mA, 1 degree per minute of scan rate, and 0.02 degree of scan step. Range of 2 theta was from 2 degree to 35 degree. At first, air-dried condition of samples was measured. After that, ethylene glycol solvated samples were measured. The result represents that all samples contain smectite, illite, chlorite. No difference in components of clay mineral is

  14. Coupling of Fe(II) oxidation in illite with nitrate reduction and its role in clay mineral transformation

    Science.gov (United States)

    Zhao, Linduo; Dong, Hailiang; Edelmann, Richard E.; Zeng, Qiang; Agrawal, Abinash

    2017-03-01

    In pedogenic and diagenetic processes, clay minerals transform from pre-existing phases to other clay minerals via intermediate interstratified clays. Temperature, pressure, chemical composition of fluids, and time are traditionally considered to be the important geological variables for clay mineral transformations. Nearly ten years ago, the role of microbes was recognized for the first time, where microbial reduction of structural Fe(III) in smectite resulted in formation of illite under ambient conditions within two weeks. However, the opposite process, the oxidation of structural Fe(II) in illite has not been studied and it remains unclear whether or not this process would result in the back reaction, e.g., from illite to smectite. The overall objective of this study was to investigate biological oxidation of structural Fe(II) in illite coupled with nitrate reduction and the effect of this process on clay mineral transformation. Laboratory incubations were set up, where structural Fe(II) in illite served as electron donor, nitrate as electron acceptor, and Pseudogulbenkiania sp. strain 2002 as mediator. Solution chemistry and gas composition were monitored over time. Mineralogical transformation resulting from bio-oxidation was characterized with X-ray diffraction and scanning and transmission electron microscopy. Our results demonstrated that strain 2002 was able to couple oxidation of structural Fe(II) in illite with reduction of nitrate to N2 with nitrite as a transient intermediate. This oxidation reaction resulted in transformation of illite to smectite and ultimately to kaolinite (illite → smectite → kaolinite transformations). This study illustrates the importance of Fe redox process in mediating the smectite-illite mineral cycle with important implications for Fe redox cycling and mineral evolution in surficial earth environments.

  15. Selenite reduction in boom clay: effect of FeS{sub 2}, clay minerals and dissolved organic matter

    Energy Technology Data Exchange (ETDEWEB)

    Bruggeman, C.; Maes, A.; Vancluysen, J. [Katholieke Universiteit Leuven, Lab. for Colloid Chemistry, Leuven (Belgium)

    2005-07-01

    In Belgium, the Boom clay layer is considered as the candidate host rock for the disposal of high-level radioactive waste (HLRW). For this disposal, Selenium 79 is considered to be a critical radionuclide and responsible for the highest dose to man over a period of tens of thousands of years. The behaviour and reactivity of Se thereby depend on its speciation and on its complex biogeochemical transformations. {sup 79}Se is thought to occur in, and be released from the solid waste matrix in a variety of redox states, including Se oxyanions such as SeO{sub 3}{sup 2-} or SeO{sub 4}{sup 2-}. The composition of the solid and liquid phases of Boom clay was published before. In this paper, the reduction of Se oxyanions was investigated by adding appropriate amounts of SeO{sub 3}{sup 2-} in over-saturation with respect to the proclaimed thermodynamical solubility of reduced Se solid phases (SeO, FeSe, FeSe{sub 2}), to a number of systems which represent Boom clay geochemical conditions. The range of systems is chosen in order to incorporate in an increasing way the different Se competing organic and inorganic phases present in the Boom clay matrix. (authors)

  16. Provenance and distribution of clay minerals in the sediments of the western continental shelf and slope of India

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, V.P.; Rao, B.R.

    -Goa (93 samples) For the convenience of description, the Saurashtra-Goa region has been divided into the Saurashtra, Gulf of Cambay-Ratnagiri and Ratnagiri-Goa sectors based on variations in clay mineral abundances. The boundaries between these sectors...

  17. Chemical and structural analysis of enhanced biochars: thermally treated mixtures of biochar, chicken litter, clay and minerals.

    Science.gov (United States)

    Lin, Y; Munroe, P; Joseph, S; Ziolkowski, A; van Zwieten, L; Kimber, S; Rust, J

    2013-03-01

    In this study biochar mixtures comprising a Jarrah-based biochar, chicken litter (CL), clay and other minerals were thermally treated, via torrefaction, at moderate temperatures (180 and 220 °C). The objectives of this treatment were to reduce N losses from CL during processing and to determine the effect of both the type of added clay and the torrefaction temperature on the structural and chemical properties of the final product, termed as an enhanced biochar (EB). Detailed characterisation indicated that the EBs contained high concentrations of plant available nutrients. Both the nutrient content and plant availability were affected by torrefaction temperature. The higher temperature (220 °C) promoted the greater decomposition of organic matter in the CL and dissociated labile carbon from the Jarrah-based biochar, which produced a higher concentration of dissolved organic carbon (DOC). This DOC may assist to solubilise mineral P, and may also react with both clay and minerals to block active sites for P adsorption. This subsequently resulted in higher concentrations of plant available P. Nitrogen loss was minimised, with up to 73% of the initial total N contained in the feedstock remaining in the final EB. However, N availability was affected by both torrefaction temperature and the nature of the clay minerals added.

  18. Clay mineral distribution in the continental shelf sediments from Krishna to Ganges river mouth, east coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, V.P.

    has resulted due to the mixing of clay mineral suite of Brahmani-Mahanadi with the Gangetic suite. A kaolinite-rich (up to 55%) assemblage with an average M/I ratio of 0.8 occurs in the eastern ghats coastal province. Variations in the abundance...

  19. Determination of the composition of the organic matter chemically stabilized by agricultural soil clay minerals: Spectroscopy and Density Fractionation

    Science.gov (United States)

    Oufqir, Sofia; Bloom, Paul; Toner, Brandy; Hatcher, Patrick

    2014-05-01

    The interactions between soil organic matter and clay minerals are considered important processes because of their ability to sequester C in soil for long periods of time, and hence control C in the global C cycle when present. However, differing results have been reported regarding the composition of the soil organic matter - aromatic fractions versus aliphatic fractions - associated with clay minerals. To clarify this critical issue and better understand the C sequestration process in soils, we aimed to determine the nature of the chemically bound natural organic matter on clay surfaces, and to probe the speciation and spatial distribution of C in the soil clay nanoparticles using direct spectroscopic measurements namely solid-state CP-MAS and DP-MAS 13C NMR spectroscopy, x-ray diffraction spectroscopy (XRD), and scanning transmission x-ray microscopy (STXM). We tested the hypotheses that peptides and polysaccharides are stabilized by the smectite-illite clay while the lipids and black carbon are a separate phase; and that they are evenly distributed on clay surfaces. A soil clay fraction (5.5% organic C) was isolated from the surface of a prairie soil (Mollisol) in southwestern Minnesota, characterized by a pH 6.0, 32.5% clay content, and 3.7% organic carbon, using a sonication-sedimentation-siphoning process in distilled water. Then was subjected to density separation combined with low energy ultrasonic dispersion to separate the free organic and black C (light fraction) from the chemically bound C (heavy fraction). The XRD results indicated a dominance of interstratified smectite-illite clays in soil. The 13C-NMR spectra of the soil clay fraction suggested that polysaccharides and polypeptides are the prevailing components of the organic matter associated with the mineral clay, with only a minor component of aromatic C. The light fraction has strong alkyl C-H bands characteristic of fatty acids plus strong C-O bands characteristic of polysaccharides, including

  20. CHARACTERISTICS OF CLAY MINERALS IN ASIAN DUST AND THEIR ENVIRONMENTAL SIGNIFICANCE

    Institute of Scientific and Technical Information of China (English)

    Zhenxing Shen; Xuxiang Li; Junji Cao; Sandrine Caquineau; Yaqiang Wang; Xiaoye Zhang

    2005-01-01

    The objectives of this research were to characterise the clay minerals composition of soil-derived dust in Northern China and to set up a mineralogical signature to trace their origin. Mineral composition of aerosol particles was investigated at Aksu, Dunhuang, Yulin, Tongliao and Changwu during an intensive field campaign period of ACE-Asia.The results show that the kaolinite (K) to chlorite (C) ratio is sensitive to the regional origin of Asian dust. Western source areas (represented by Aksu) displayed the lowest K/C ratio of 0.3 (average), while it was found to increase up to 0.70(average) upon moving towards northern source areas (represented by Yulin). By studying transported dust in a deposition area representative of the Chinese Loess Plateau, the usefulness of the K/C ratio, when associated with back air-mass trajectories, was found to lie in revealing the origin of the dust. Comparison of the mineralogical data between Asian dust and Sahara dust, shows that the K/C ratio is also an effective signature to identify the source areas on a hemisphere scale.

  1. Effect of organic matter properties, clay mineral type and thermal maturity on gas adsorption in organic-rich shale systems

    Science.gov (United States)

    Zhang, Tongwei; Ellis, Geoffrey S.; Ruppel, Stephen C.; Milliken, Kitty; Lewan, Mike; Sun, Xun; Baez, Luis; Beeney, Ken; Sonnenberg, Steve

    2013-01-01

    A series of CH4 adsorption experiments on natural organic-rich shales, isolated kerogen, clay-rich rocks, and artificially matured Woodford Shale samples were conducted under dry conditions. Our results indicate that physisorption is a dominant process for CH4 sorption, both on organic-rich shales and clay minerals. The Brunauer–Emmett–Teller (BET) surface area of the investigated samples is linearly correlated with the CH4 sorption capacity in both organic-rich shales and clay-rich rocks. The presence of organic matter is a primary control on gas adsorption in shale-gas systems, and the gas-sorption capacity is determined by total organic carbon (TOC) content, organic-matter type, and thermal maturity. A large number of nanopores, in the 2–50 nm size range, were created during organic-matter thermal decomposition, and they significantly contributed to the surface area. Consequently, methane-sorption capacity increases with increasing thermal maturity due to the presence of nanopores produced during organic-matter decomposition. Furthermore, CH4 sorption on clay minerals is mainly controlled by the type of clay mineral present. In terms of relative CH4 sorption capacity: montmorillonite ≫ illite – smectite mixed layer > kaolinite > chlorite > illite. The effect of rock properties (organic matter content, type, maturity, and clay minerals) on CH4 adsorption can be quantified with the heat of adsorption and the standard entropy, which are determined from adsorption isotherms at different temperatures. For clay-mineral rich rocks, the heat of adsorption (q) ranges from 9.4 to 16.6 kJ/mol. These values are considerably smaller than those for CH4 adsorption on kerogen (21.9–28 kJ/mol) and organic-rich shales (15.1–18.4 kJ/mol). The standard entropy (Δs°) ranges from -64.8 to -79.5 J/mol/K for clay minerals, -68.1 to -111.3 J/mol/K for kerogen, and -76.0 to -84.6 J/mol/K for organic-rich shales. The affinity of CH4 molecules for sorption on organic matter

  2. Study of adsorption of Phenanthrene on Different Types of Clay Minerals; Estudio de Adsorcion de Fenentreno en Diferentes Tipos de Arcillas

    Energy Technology Data Exchange (ETDEWEB)

    Contreras, M. L.; Escolano, O.; Rodriguez, V.; Diaz, F. J.; Perez, R.; Garcia, S.; Garcia Frutos, F. J.

    2003-07-01

    The fate and behaviour of non-ionic hydrophobic organic compounds in deep soil is mainly controlled by the mineral fraction present in the soil due to the very low organic carbon content of the deep soil. The mineral fraction that may greatly influence the fate and transport of these compounds due to its presence and properties are the clay minerals. Clay mineral also become increasingly important in low organic matter content soils. There tree, studies of non-ionic hydrophobic organic compounds adsorption on clay minerals without organic matter are necessary lo better understand the fate and transport of these compounds. In this work we used phenanthrene as model compound of non-ionic hydrophobic organic compound and four pure clay minerals: kaolinite, illite, montmorillonite, and vermiculite including muscovite mica. These clays minerals are selected due to its abundance in represent ve Spanish soils and different properties as its structural layers and expanding capacity. Batch experiments were performed using phenanthrene aqueous solutions and the clays selected. Phenanthrene sorption isotherms for all clays, except muscovite mica, were best described by the Freundlich model. Physical sorption on the external surfaces is the most probable adsorption mechanisms. In this sense, the presence of non-polar nano-sites on clay surfaces could determine the adsorption of phenanthrene by hydrophobic interaction on these sites. (Author) 22 refs.

  3. Bio-Mobilization of Potassium from Clay Minerals: II. By Ectomycorrhizal Fungi

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Ectomycorrhizal fungi, including Cenococcum geophilurn SIV (Cg SIV), and Pisolithus tinctorius 2144(Pt 2144), 441 (Pt 441) and XC1 (Pt XC1), were cultured in Pachlewski liquid medium with H2KPO4, KClsaturated vermiculite and mica as K sources, respectively, to investigate the mechanism of K absorption and mobilization by the fungi. Fungal growth rate, K absorption and mobilization varied significantly among the fungal species. Faster growth and greater K accumulation in Pt XC1 than Pt 2 144, Pt 441 and Cg siv were observed. Ectomycorrhizal fungi depressed HCl-soluble K in minerals after successive extractions by water and NH4OAc. Ratio of the total amount of K, including water-, NH4OAc- and HCl-soluble K, lost from substrates to the K accumulated in fungal colonies was less than 60%. These reveal that the ectomycorrhizal fungi could utilize K in interlayer and structural pools, which are usually unavailable for plants in short period. Large differences in the depletion of K in interlayer and structural pools by fungi were observed at fungal harvest. Taking into account the nutrient absorption by ectomycorrhizal fungi in symbionts and the direct contact between hyphae and soils, the fungi species colonized on the root surfaces seemed to be related to the effectiveness of mycorrhizas to utilize K in soils. Ectomycorrhizal fungi differed in the efflux of protons and oxalate. Pt XC1 was observed to have greatest ability to effuse protons and oxalate among the fungi adopted in the experiment. Furthermore, the higher the concentrations of protons and oxalate in the liquid culture solutions, the larger the depletion of K in interlayer and structural pools in minerals by fungi. Protons could replace interlayer K and chelation of oxalate with Fe and A1 in crystal lattice could cause weathering of clay minerals. So, protons and oxalate produced by ectomycorrhizal fungi might play an important role in K mobilization in these two pools.

  4. Calcium-ammonium exchange experiments on clay minerals using a (45)Ca tracer technique in marine pore water.

    Science.gov (United States)

    Ockert, Charlotte; Wehrmann, Laura M; Kaufhold, Stephan; Ferdelman, Tim G; Teichert, Barbara M A; Gussone, Nikolaus

    2014-01-01

    Understanding cation exchange processes is important for evaluating early diagenetic and synsedimentary processes taking place in marine sediments. To quantify calcium (Ca) exchange and Ca-ammonium exchange in a seawater environment, we performed experiments with a radioactive (45)Ca tracer on clay mineral standards (Fithian illite, montmorillonite and kaolinite) and marine sediments from the North Atlantic Integrated Ocean Drilling Program Site U1306A in artificial seawater (ASW). The results show that equilibrium during the initial attachment of Ca as well as the exchange of Ca by [Formula: see text] is attained in less than 2 min. On average 8-20% of the exchangeable sites of the clay minerals were occupied by Ca in a seawater medium. The conditional selectivity coefficient, describing the [Formula: see text] exchange in ASW is mineral specific and it was determined to be 0.07 for montmorillonite, 0.05 for a natural marine sediment and 0.013 for Fithian illite.

  5. Clay mineral records of East Asian monsoon evolution during late Quaternary in the southern South China Sea

    Institute of Scientific and Technical Information of China (English)

    LIU Zhifei; C. Colin; A. Trentesaux; D. Blamart

    2005-01-01

    High-resolution clay mineral records combined with oxygen isotopic stratigraphy over the past 190 ka during late Quaternary from core MD01-2393 off the Mekong River in the southern South China Sea are reported to reconstruct a history of East Asian monsoon evolution.The dominating clay mineral components indicate a strong glacial-interglacial cyclicity, with high glacial illite, chlorite, and kaolinite contents and high interglacial smectites content. The provenance analysis indicates the direct input of clay minerals via the Mekong River drainage basin.Illite and chlorite derived mainly from the upper reach of the Mekong River, where physical erosion of meta-sedimentary rocks is dominant. Kaolinite derived mainly from active erosion of inhered clays from reworked sediments in the middle reaches. Smectites originated mainly through bisiallitic soils in the middle to lower reaches of the Mekong River. The smectites/(illite+chlorite)and smectites/kaolinite ratios are determined as mineralogical indicators of East Asian monsoon variations. Relatively high ratios occur during interglacials and indicate strengthened summer-monsoon rainfall and weakened winter-monsoon winds; relatively lower ratios happened in glacials, indicating intensified winter monsoon and weakened summer monsoon. The evolution of the summer and winter monsoons provides an almost linear response to the summer insolation of the Northern Hemisphere, implying an astronomical forcing of the East Asian monsoon evolution.

  6. Heavy sediment influx during early Holocene: Inference from clay mineral studies in a core from the western Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Reddy, N.P.C.; Rao, K

    , 133 , 227 ? 248. 21. Prell, W. C., Hutson, W. H., Williams, D. F., Be, A. W. H., Gei t senauer, K. and Molfineo, B., Quat. Res ., 1980, 14 , 309 ? 336. 22. Ramaswamy, V. and Parthiban, G., Geol. Surv. India Spec. Publ ., 1992 , 29 , 25...: Inf erence from clay mi n eral studies in a core from the Western Bay of Bengal N. P. C. Reddy* and K. Mohana Rao Regional Centre, National Institute of Oceanography, 176, Lawson?s Bay, Visakhapatnam 530 017, India Clay mineral studies...

  7. Distribution of clay minerals in surface sediments of the western Gulf of Thailand: Sources and transport patterns

    Science.gov (United States)

    Shi, Xuefa; Liu, Shengfa; Fang, Xisheng; Qiao, Shuqing; Khokiattiwong, Somkiat; Kornkanitnan, Narumol

    2015-06-01

    A high density sampling program during two joint China-Thailand scientific cruises in 2011-2012 included collection of 152 gravity box cores in the Gulf of Thailand (GoT). Samples from the top 5 cm of each core were analyzed by X-ray diffraction for clay mineral content. Several systemic analytical approaches were applied to examine the distribution pattern and the constraint factors of clay minerals in the surface sediments of the western GoT. The clay minerals mainly comprise illite, kaolinite, chlorite and smectite, having the average weight percent distributions of 50%, 34%, 14% and 2%, respectively. Based on the spatial distribution characteristics and statistical results, the study area can be classified into three provinces. Province I contains high concentrations of smectite, and covers the northern GoT, sediments in this province are mainly from rivers discharging into the upper GoT, especially the Chao Phraya and Mae Klong Rivers. Sediments in Province II are characterized by higher values of illite, located in the central GoT, where fine sediments are contributed by the Mekong River and from the South China Sea. Province Ш, in the coastal regions of southwestern GoT close to Malaysia, exhibits a clay mineral assemblage with complex distribution patterns, and may contain terrestrial materials from the Mae Klong River as well as re-suspended sediments. Results of integrative analysis also demonstrate that the hydrodynamic environment in the study area, especially the seasonal various circumfluence and eddies, play an important role in the spatial distribution and dispersal of clay fraction in sediments.

  8. Refinements of water parameters for molecular dynamics: Simulations of adsorption at the clay mineral/aqueous solution interface

    DEFF Research Database (Denmark)

    Schäfer, L.; Yu, C.; Teppen, B.J.;

    1999-01-01

    In the context of a long-term program involving molecular dynamics simulations of adsorption phenomena at the clay mineral/aqueous solution interface, we are testing the viability of combining a force field that we developed specificially for clays with other, independently derived potential...... parameters for molecular species which are important in clay adsorption. For the current study the importance of variations in the potential parameters of water were investigated and polarization effects on oxygen studied as a function of intermolecular interactions. For this purpose ab initio MP2/6-311GG...... atomic charges were determined for several oligomers of water and for the water dimer at different intermolecular separations. Charge variations of up to ~0.1 electron charge unit on oxygen are found and, together with changes in van der Waals constants, their significance for dynamics simulations...

  9. Characteristics of Lead Sorption on Clay Minerals in Relation to Metal Oxides

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Difference of montmorillonite (Mt), illite (It) and kaolinite (Kt) in lead sorption characteristics and the effects of amorphous Fe and Al oxide coatings on the haracteristics were experimentally studied with logistic model. The sorption curves had sigmoid feature due to use of acetate-type buffer solution. With the modelthe sorption process could be divided into four stages and the sorption characteristics at the stages were discussed. The results showed that, after Mt, It and Kt were coated by amorphous Fe oxide, their maximum sorption capacity (MSC) and percentage of high-SSC concentration scope (HCS) of Pb2+ increased markedly but the specific sorption capacity (SSC) decreased. With regard to effects of amorphous Al oxide coating,except for It+Al, the SSC of other samples showed a downtrend, despite that their MSC remained unchanged.Eventually, the gray correlation degrees to Pb2+ sorption for different physicochemical characteristics of the clay minerals were indicated to be higher for hydronium, zero point of surface charge and hydroxy, but lower for specific surface area, density of surface charge and amount of surface charges.

  10. Vanadium recovery from clay vanadium mineral using an acid leaching method

    Institute of Scientific and Technical Information of China (English)

    LI Haoran; FENG Yali; LIANG Jianglong; LUO Xiaobing; DU Zhuwei

    2008-01-01

    A technique including direct acid leaching,vanadium precipitation with alkaline,sodium hydroxide releaching,impurity removing by adjusting pH value,precipitation vanadium with ammonium chloride,and vanadium pentoxide by roasting steps was proposed according to the characteristic of Xichuan clay vanadium mineral.The factors influencing leaching vanadium such as temperature and the concentration of sulfuric acid were investigated and optimized.The experimental results indicate that the extract ratios of V2O5 can reach 94% and 92% at a sodium chlorate ratio of 3% and a manganese dioxide ratio of 3%,respectively.A completely chemical precipitation method was adopted to decontaminate and enrich the vanadium in the acid leaching solution.The X-ray diffraction (XRD) pattern and the purity analysis of vanadium pentoxide indicate that the purity of final vanadium pentoxide can reach 99% and meet the standard specifications.The total recovery can reach about 75%.The technique has the characteristics of simplicity,less investlnent,and more environment safety as compared with the traditional salt roasting method.

  11. Size distributions of coastal ocean suspended particulate inorganic matter: Amorphous silica and clay minerals and their dynamics

    Science.gov (United States)

    Zhang, Xiaodong; Stavn, Robert H.; Falster, Alexander U.; Rick, Johannes J.; Gray, Deric; Gould, Richard W.

    2017-04-01

    Particulate inorganic matter (PIM) is a key component in estuarine and coastal systems and plays a critical role in trace metal cycling. Better understanding of coastal dynamics and biogeochemistry requires improved quantification of PIM in terms of its concentration, size distribution, and mineral species composition. The angular pattern of light scattering contains detailed information about the size and composition of particles. These volume scattering functions (VSFs) were measured in Mobile Bay, Alabama, USA, a dynamic, PIM dominated coastal environment. From measured VSFs, we determined through inversion the particle size distributions (PSDs) of major components of PIM, amorphous silica and clay minerals. An innovation here is the extension of our reported PSDs significantly into the submicron range. The PSDs of autochthonous amorphous silica exhibit two unique features: a peak centered at about 0.8 μm between 0.2 and 4 μm and a very broad shoulder essentially extending from 4 μm to >100 μm. With an active and steady particle source from blooming diatoms, the shapes of amorphous silica PSDs for sizes 10 μm inside the bay, likely due to wind-induced resuspension of larger frustules that have settled. Compared to autochthonous amorphous silica, the allochthonous clay minerals are denser and exhibit relatively narrower PSDs with peaks located between 1 and 4 μm. Preferential settling of larger mineral particles as well as the smaller but denser illite component further narrowed the size distributions of clay minerals as they were being transported outside the bay. The derived PSDs also indicated a very dynamic situation in Mobile Bay when a cold weather front passed through during the experiment. With northerly winds of speeds up to 15 m s-1, both amorphous silica and clay minerals showed a dramatic increase in concentration and broadening in size distribution outside the exit of the barrier islands, indicative of wind-induced resuspension and subsequent

  12. Determination of Tracer Arrival Times and Volumetric Contents of Clay and Mineral Fines Using Visible NearInfrared Spectroscopy

    DEFF Research Database (Denmark)

    Hermansen, Cecilie; Møldrup, Per; Karup, Dan;

    to give rapid and accurate predictions of soil functional properties related to texture and organic matter, such as water retention and compaction. We evaluated visNIR spectroscopy as a rapid and indirect method for predicting selected BTC tracer mass arrival times (TMATs) and the volumetric contents...... and volumetric contents of clay and mineral fines were correlated to spectral data with partial least squares regression on a calibration set (133 samples) and then tested on a validation set (44 samples). We obtained accurate visNIR predictions of the 5% TMAT and volumetric contents of clay and mineral fines....... VisNIR predictions of later TMATs of 10, 15, 20, 25, 30, 40 and 50% showed decreasing accuracy with increasing TMAT, which probably reflect decreasing correlation with soil texture....

  13. Characterization of Adsorbed Alkali Metal Ions in 2:1 Type Clay Minerals from First-Principles Metadynamics.

    Science.gov (United States)

    Ikeda, Takashi; Suzuki, Shinichi; Yaita, Tsuyoshi

    2015-07-30

    Adsorption states of alkali metal ions in three kinds of 2:1 type clay minerals are systematically investigated via first-principles-based metadynamics. Our reconstructed free energy surfaces in a two-dimensional space of coordination numbers specifically employed as collective variables for describing the interlayer cations show that an inner-sphere (IS) complex is preferentially formed for Cs(+) in the 2:1 type trioctahedral clay minerals with saponite-like compositions, where lighter alkali metal ions show a tendency to form an outer-sphere one instead. The strong preference for an IS complex observed for Cs(+) is found to result partially from the capability of recognizing selectively Cs(+) ions at the basal O atoms with the Lewis basicity significantly enhanced by the isomorphic substitution in tetrahedral sheets.

  14. Role of Clay Minerals in Long-Distance Transport of Landslides in Valles Marineris, Mars

    Science.gov (United States)

    Watkins, J.; Ehlmann, B. L.; Yin, A.

    2014-12-01

    Long-runout (> 50 km) subaerial landslides are rare on Earth, but are common features episodically shaping Mars' Valles Marineris (VM) trough system over the past 3.5 billion years. They display two end-member morphologies: a thick-skinned inner zone, characterized by fault-bounded, rotated blocks near their source region, and a thin-skinned, exceptionally long-runout outer zone, characterized by thin sheets spreading over 10s of km across the trough floor. Four decades of studies on the latter have resulted in two main competing hypotheses to explain their long-distance transport: (1) movement of landslides over layers of trapped air or soft materials containing ice or snow, enabling basal lubrication, and (2) fluidization of landslide materials with or without the presence of water and volatiles. To address this issue, we examine the mineralogic composition of landslides across VM using Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) near-infrared spectral data analysis coupled with detailed geologic mapping and morphometric analysis of satellite images. Our survey reveals a general correlation between transport distance, significant lateral spreading, and the presence of hydrated silicates among VM landslides. Given that smectite clay absorbs water into its layered crystal structure and can reduce the friction coefficient by a factor of three v. that of dry rocks, these results suggest that hydrated silicates played a decisive role in facilitating long-runout landslide transport in VM. We propose that, concurrent with downslope failure and sliding of broken trough-wall rock, frontal landslide masses overrode and entrained hydrated-silicate-bearing trough-floor deposits, lubricating the basal sliding zones and permitting the landslide outer zones to spread laterally while moving forward over the low-friction surface. The key participation of hydrated silicates in episodic, sustained landslide activity throughout the canyon implies that clay minerals

  15. Redox properties of structural Fe in clay minerals. 1. Electrochemical quantification of electron-donating and -accepting capacities of smectites.

    Science.gov (United States)

    Gorski, Christopher A; Aeschbacher, Michael; Soltermann, Daniela; Voegelin, Andreas; Baeyens, Bart; Marques Fernandes, Maria; Hofstetter, Thomas B; Sander, Michael

    2012-09-04

    Clay minerals often contain redox-active structural iron that participates in electron transfer reactions with environmental pollutants, bacteria, and biological nutrients. Measuring the redox properties of structural Fe in clay minerals using electrochemical approaches, however, has proven to be difficult due to a lack of reactivity between clay minerals and electrodes. Here, we overcome this limitation by using one-electron-transfer mediating compounds to facilitate electron transfer between structural Fe in clay minerals and a vitreous carbon working electrode in an electrochemical cell. Using this approach, the electron-accepting and -donating capacities (Q(EAC) and Q(EDC)) were quantified at applied potentials (E(H)) of -0.60 V and +0.61 V (vs SHE), respectively, for four natural Fe-bearing smectites (i.e., SWa-1, SWy-2, NAu-1, and NAu-2) having different total Fe contents (Fe(total) = 2.3 to 21.2 wt % Fe) and varied initial Fe(2+)/Fe(total) states. For every SWa-1 and SWy-2 sample, all the structural Fe was redox-active over the tested E(H) range, demonstrating reliable quantification of Fe content and redox state. Yet for NAu-1 and NAu-2, a significant fraction of the structural Fe was redox-inactive, which was attributed to Fe-rich smectites requiring more extreme E(H)-values to achieve complete Fe reduction and/or oxidation. The Q(EAC) and Q(EDC) values provided here can be used as benchmarks in future studies examining the extent of reduction and oxidation of Fe-bearing smectites.

  16. Preparation and Coagulation Behavior of a Novel Multiple Flocculant Based on Cationic Polymer, Hydroxy Aluminum, and Clay Minerals

    Directory of Open Access Journals (Sweden)

    Feng-shan Zhou

    2015-01-01

    Full Text Available Cationic polymer, hydroxy aluminum, and clay minerals are three flocculants with different action mechanisms and a more cost-efficient multiple flocculant can be prepared by compositing them through appropriate technology. All of attapulgite (ATP, clay minerals containing magnesium, aluminum, and silicate, are porous environmental mineral material with good absorbability and have found wide applications in industrial sewage treatment. With polyaluminum chloride (PAC, poly(dimethyl diallyl ammonium chloride (PDMDAAC, and attapulgite (ATP clay being the main raw materials, multiple flocculant CMHa (liquid with good storage stability was prepared and its optimized blending mass percent was PDMDAAC of 2%-3%, ATP of 4%–6%, and PAC of 20%–30%. The liquid poly(dimethyl diallyl ammonium chloride (PDMDAAC was firstly loaded on solid material in kneader and then mixed in certain proportion with PAC and ATP to prepare solid CMHa convenient for storage and transportation. The optimized mass ratio is PAC : ATP : PDMDAAC = 80 : 10 : 2.4. When this multiple flocculant was used to treat domestic sewage, coal washing sewage, dyeing wastewater, and papermaking wastewater, its equivalent dosage was just 50% of PAC, while overall production cost has been reduced to about 40%, viewing showing broad application prospect.

  17. Formation of replicating saponite from a gel in the presence of oxalate: implications for the formation of clay minerals in carbonaceous chondrites and the origin of life.

    Science.gov (United States)

    Schumann, Dirk; Hartman, Hyman; Eberl, Dennis D; Sears, S Kelly; Hesse, Reinhard; Vali, Hojatollah

    2012-06-01

    The potential role of clay minerals in the abiotic origin of life has been the subject of ongoing debate for the past several decades. At issue are the clay minerals found in a class of meteorites known as carbonaceous chondrites. These clay minerals are the product of aqueous alteration of anhydrous mineral phases, such as olivine and orthopyroxene, that are often present in the chondrules. Moreover, there is a strong correlation in the occurrence of clay minerals and the presence of polar organic molecules. It has been shown in laboratory experiments at low temperature and ambient pressure that polar organic molecules, such as the oxalate found in meteorites, can catalyze the crystallization of clay minerals. In this study, we show that oxalate is a robust catalyst in the crystallization of saponite, an Al- and Mg-rich, trioctahedral 2:1 layer silicate, from a silicate gel at 60°C and ambient pressure. High-resolution transmission electron microscopy analysis of the saponite treated with octadecylammonium (n(C)=18) cations revealed the presence of 2:1 layer structures that have variable interlayer charge. The crystallization of these differently charged 2:1 layer silicates most likely occurred independently. The fact that 2:1 layer silicates with variable charge formed in the same gel has implications for our understanding of the origin of life, as these 2:1 clay minerals most likely replicate by a mechanism of template-catalyzed polymerization and transmit the charge distribution from layer to layer. If polar organic molecules like oxalate can catalyze the formation of clay-mineral crystals, which in turn promote clay microenvironments and provide abundant adsorption sites for other organic molecules present in solution, the interaction among these adsorbed molecules could lead to the polymerization of more complex organic molecules like RNA from nucleotides on early Earth.

  18. Formation of replicating saponite from a gel in the presence of oxalate: implications for the formation of clay minerals in carbonaceous chondrites and the origin of life

    Science.gov (United States)

    Schumann, Dirk; Hartman, Hyman; Eberl, Dennis D.; Sears, S. Kelly; Hesse, Reinhard; Vali, Hojatollah

    2012-01-01

    The potential role of clay minerals in the abiotic origin of life has been the subject of ongoing debate for the past several decades. At issue are the clay minerals found in a class of meteorites known as carbonaceous chondrites. These clay minerals are the product of aqueous alteration of anhydrous mineral phases, such as olivine and orthopyroxene, that are often present in the chondrules. Moreover, there is a strong correlation in the occurrence of clay minerals and the presence of polar organic molecules. It has been shown in laboratory experiments at low temperature and ambient pressure that polar organic molecules, such as the oxalate found in meteorites, can catalyze the crystallization of clay minerals. In this study, we show that oxalate is a robust catalyst in the crystallization of saponite, an Al- and Mg-rich, trioctahedral 2:1 layer silicate, from a silicate gel at 60°C and ambient pressure. High-resolution transmission electron microscopy analysis of the saponite treated with octadecylammonium (n(C)=18) cations revealed the presence of 2:1 layer structures that have variable interlayer charge. The crystallization of these differently charged 2:1 layer silicates most likely occurred independently. The fact that 2:1 layer silicates with variable charge formed in the same gel has implications for our understanding of the origin of life, as these 2:1 clay minerals most likely replicate by a mechanism of template-catalyzed polymerization and transmit the charge distribution from layer to layer. If polar organic molecules like oxalate can catalyze the formation of clay-mineral crystals, which in turn promote clay microenvironments and provide abundant adsorption sites for other organic molecules present in solution, the interaction among these adsorbed molecules could lead to the polymerization of more complex organic molecules like RNA from nucleotides on early Earth.

  19. Non-selective oxidation of humic acid in heterogeneous aqueous systems: a comparative investigation on the effect of clay minerals.

    Science.gov (United States)

    Kavurmaci, Sibel Sen; Bekbolet, Miray

    2014-01-01

    Application of photocatalysis for degradation of natural organic matter (NOM) has received wide interest during the last decades. Besides NOM, model compounds more specifically humic acids (HAs) were also studied. As a continuation of the previous research, TiO2 photocatalytic degradation of HA was investigated in the presence of clay minerals, i.e., montmorillonite (Mt) and kaolinite (Kt). Degradation of HA was expressed by the pseudo-first-order kinetic modelling of dissolved organic carbon (DOC) and UV-VIS parameters (Colour436 and UV254). A slight rate enhancement was attained for Colour436 and UV254 in the presence of either Mt or Kt. The presence of clay particles did not significantly change the DOC degradation rate of HA. The effect of ionic strength (Ca2+ loading from 5 x 10(-4) M to 5 x 1(-3) M) was also assessed for the photocatalytic degradation of sole HA and HA in the presence of either Mt or Kt. Following photocatalytic treatment, molecular size distribution profiles of HA were presented. Besides the effective removal of higher molecular size fractions (100 and 30 kDa fractions), transformation to lower molecular size fractions (clay minerals. Scanning electron microscopic images with the energy dispersive X-ray analysis confirmed the diversities in surface morphologies of the binary and ternary systems composed of HA, TiO2 and Mt or Kt both prior to and following photocatalysis. This study demonstrated that photocatalysis could be applicable for DOC degradation in the presence of clay minerals in natural waters.

  20. Degradative crystal–chemical transformations of clay minerals under the influence of cyanobacterium-actinomycetal symbiotic associations

    Directory of Open Access Journals (Sweden)

    Ekaterina Ivanova

    2014-04-01

    Full Text Available Cyanobacteria and actinomycetes are essential components of soil microbial community and play an active role in ash elements leaching from minerals of the parent rock. Content and composition of clay minerals in soil determine the sorption properties of the soil horizons, water-holding capacity of the soil, stickiness, plasticity, etc. The transformative effect of cyanobacterial–actinomycetes associations on the structure of clay minerals – kaolinite, vermiculite, montmorillonite, biotite and muscovite – was observed, with the greatest structural lattice transformation revealed under the influence of association in comparison with monocultures of cyanobacterium and actinomycete. The range of the transformative effect depended both on the type of biota (component composition of association and on the crystal–chemical parameters of the mineral itself (trioctahedral mica – biotite, was more prone to microbial degradation than the dioctahedral – muscovite. The formation of the swelling phase – the product of biotite transformation into the mica–vermicullite mixed-layered formation was revealed as a result of association cultivation. Crystal chemical transformation of vermiculite was accompanied by the removal of potassium (К, magnesium (Mg and aluminum (Al from the crystal lattice. The study of such prokaryotic communities existed even in the early stages of the Earth's history helps to understand the causes and nature of the transformations undergone by the atmosphere, hydrosphere and lithosphere of the planet.contribution of treatments on structure induces and model parameters are discussed in the paper.

  1. [Mineralogy and genesis of mixed-layer clay minerals in the Jiujiang net-like red soil].

    Science.gov (United States)

    Yin, Ke; Hong, Han-Lie; Li, Rong-Biao; Han, Wen; Wu, Yu; Gao, Wen-Peng; Jia, Jin-Sheng

    2012-10-01

    Mineralogy and genesis were investigated using X-ray diffraction (XRD), Fourier infrared absorption spectroscopy (FTIR) and high resolution transmission electron microscopy (HRTEM) to understand the mineralogy and its genesis significance of mixed-layer clay minerals in Jiujiang red soil section. XRD and FTIR results show that the net-like red soil sediments are composed of illite, kaolinite, minor smectite and mixed-layer illite-smectite and minor mixed-layer kaolinite-smectite. HRTEM observation indicates that some smectite layers have transformed into kaolinite layers in net-like red soil. Mixed-layer illite-smectite is a transition phase of illite transforming into smectite, and mixed-layer kaolinite-smectite is a transitional product relative to kaolinite and smectite. The occurrence of two mixed-layer clay species suggests that the weathering sequence of clay minerals in net-like red soil traversed from illite to mixed-layer illite-smectite to smectite to mixed-layer kaolinite-smectite to kaolinite, which indicates that net-like red soil formed under a warm and humid climate with strengthening of weathering.

  2. Burial diagenetic processes of clay mineral and non-clay mineral, quartz cementation and dissolution in sandstones and mudstones of the Siri Canyon, Danish North Sea

    DEFF Research Database (Denmark)

    Kazerouni, Afsoon Moatari; Friis, Henrik; Svendsen, Johan Byskov

    reprecipitate as opal, quartz or other mineral phases inside the shale itself. The deep marine sandstones in the Siri Canyon, Danish North Sea, have been reported to import significant amounts of dissolve silica from adjacent Paleocene shales during early diagenesis, and the authigenesis of silica developed...

  3. Alteration of glass as a possible source of clay minerals on Mars

    Science.gov (United States)

    Gooding, J. L.; Keil, K.

    1978-01-01

    Thermodynamic calculations show that, under present Martian surface conditions, favorable gas-solid weathering products of feldspar glasses should include beidellites (clays of the montmorillonite series) + carbonates + quartz. The gas-solid weathering of mafic silicate glass ( of volcanic or impact origin) may similarly favor the production of metastable Fe-rich montmorillonite clays. Simple mass-balance calculations suggest that gas-solid weathering of Martian proto-regolith containing 10% glass could conceivably produce a global blanket of clays at a rate of at least 0.4 cm/b.y. The production rate should be expected to increase significantly with the glass content and rate of reworking of the proto-regolith and with the availability of water. Complete extraction of altered glass from a lunar-like proto-regolith might yield a global Martian clay blanket about 10-100 cm in thickness.

  4. Clay minerals and metal oxides strongly influence the structure of alkane-degrading microbial communities during soil maturation.

    Science.gov (United States)

    Steinbach, Annelie; Schulz, Stefanie; Giebler, Julia; Schulz, Stephan; Pronk, Geertje J; Kögel-Knabner, Ingrid; Harms, Hauke; Wick, Lukas Y; Schloter, Michael

    2015-07-01

    Clay minerals, charcoal and metal oxides are essential parts of the soil matrix and strongly influence the formation of biogeochemical interfaces in soil. We investigated the role of these parental materials for the development of functional microbial guilds using the example of alkane-degrading bacteria harbouring the alkane monooxygenase gene (alkB) in artificial mixtures composed of different minerals and charcoal, sterile manure and a microbial inoculum extracted from an agricultural soil. We followed changes in abundance and community structure of alkane-degrading microbial communities after 3 and 12 months of soil maturation and in response to a subsequent 2-week plant litter addition. During maturation we observed an overall increasing divergence in community composition. The impact of metal oxides on alkane-degrading community structure increased during soil maturation, whereas the charcoal impact decreased from 3 to 12 months. Among the clay minerals illite influenced the community structure of alkB-harbouring bacteria significantly, but not montmorillonite. The litter application induced strong community shifts in soils, maturated for 12 months, towards functional guilds typical for younger maturation stages pointing to a resilience of the alkane-degradation function potentially fostered by an extant 'seed bank'.

  5. [X-ray powder diffraction of clay minerals of SZK01 core of Zabuye Lake, Tibetan Plateau].

    Science.gov (United States)

    Zhang, Xue-Fei; Zheng, Mian-Ping

    2014-11-01

    The present article chooses the core from the borehole SZK01 in Zabuye Lake as the main research object. According to the results of X-ray powder diffraction of clay minerals, the major components are illite, illite and smectite mixed layer mineral (I/S), kaolinite and chlorite. According to the different species and contents of clay, integration of the characteristics of mineral and the results of Δ18O, we reestablished the evolution process of paleoclimate in Zabuye Lake. In compaison with SZK02 core in Zabuye, Greenland GISP2 and GRIP and Guliya ice core, it contains 5 stages since 115 ka in Zabuye: the last interglacial (15-75.5 ka), the earlier last glacial (75.5-60 ka), the interstage of the last glacial (60-30.1 ka), the last glacial maximum (30.1-16.7 ka) and deglacial-holocene (since 16.7 ka). We also recognized 6 Heinrich events (H1-H6) and warm event in 71 ka. In particular, the content of kaolinite is low, with the negative-skewed value of Δ18O in 52-53 ka, while the value of Δ18O in SZK02 and Guliya ice core is negative-skewed too, indicating the cold event in Tibet plateau, named H5-1. All the above demonstrated that the climate in Tibet plateau is global since the earlier last glacial, and it also has regional characteristics.

  6. CHARACTERISTICS OF FLUORIDE EMISSION FROM FIVE CLAY MINERALS AS AFFECTED BY TEMPERATURE,HEATING TIME AND ADDITION OF CALCIUM COMPOUNDS

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Characteristics of fluoride emission from five clay minerals (montmorillonite, kaolinite, vermiculite, geothite, and allophane) as affected by temperature, heating time and addition of calcium compounds were studied. Marked increase of the fluoride emission rate was noticed with increase of temperature. The fluoride release, began at 500 ℃-600 ℃, and the main bulk of the fluoride emission occurred at the temperature of about 800 ℃. The loss of crystalline water was primarily responsible for the increase of fluoride emission. When minerals were heated at 800 ℃, The fluoride emission rate from the clay minerals reached the highest after heating for 1 hour. The samples treated by CaO, CaCO3, Ca(OH)2, Ca3(PO4)2, and CaSO4 had 55.45%, 59.58%, 46.45%, 54.31%, 31.25% reduction in the fluoride emission from montmorillonite at the temperature of 800 ℃, respectively. CaCO3 had the highest fluoride fixing capacity compared to other calcium compounds.

  7. Sorption of organic cations to phyllosilicate clay minerals: CEC-normalization, salt dependency, and the role of electrostatic and hydrophobic effects.

    Science.gov (United States)

    Droge, Steven T J; Goss, Kai-Uwe

    2013-12-17

    Sorption to the phyllosilicate clay minerals Illite, kaolinite, and bentonite has been studied for a wide variety of organic cations using a flow-through method with fully aqueous medium as the eluent. Linear isotherms were observed at concentrations below 10% of the cation-exchange capacity (CEC) for Illite and kaolinite and below 1 mmol/kg (<1% CEC) for bentonite. Sorption to clays was strongly influenced by the electrolyte composition of the eluent but with a consistent trend for a diverse set of compounds on all clays, thus allowing for empirical correction factors. When sorption affinities for a given compound to a given clay are normalized to the CEC of the clay, the differences in sorption affinities between clays are reduced to less than 0.5 log units for most compounds. Although CEC-normalized sorption of quaternary ammonium compounds to clay was up to 10-fold higher than CEC-normalized sorption to soil organic matter, CEC-normalized sorption for most compounds was comparable between clays and soil organic matter. The clay fraction is thus a potentially relevant sorption phase for organic cations in many soils. The sorption data for organic cations to clay showed several regular trends with molecular structure but also showed quite a few systematic effects that we cannot explain. A model on the basis of the molecular size and charge density at the ionized nitrogen is used here as a tool to obtain benchmark values that elucidate the effect of specific polar moieties on the sorption affinity.

  8. [Rapid determination of major and trace elements in the salt lake clay minerals by X-ray fluorescence spectrometry].

    Science.gov (United States)

    Wang, Xiao-Huan; Meng, Qing-Fen; Dong, Ya-Ping; Chen, Mei-Da; Li, Wu

    2010-03-01

    A rapid multi-element analysis method for clay mineral samples was described. This method utilized a polarized wave-length dispersive X-ray fluorescence spectrometer--Axios PW4400, which had a maximum tube power of 4 000 watts. The method was developed for the determination of As, Mn, Co, Cu, Cr, Dy, Ga, Mo, P, Pb, Rb, S, Sr, Ni, ,Cs, Ta, Th, Ti, U, V, Y, Zn, Zr, MgO, K2O, Na2O, CaO, Fe2O3, Al2O3, SiO2 and so on. Thirty elements in clay mineral species were measured by X-ray fluorescence spectrometry with pressed powder pellets. Spectral interferences, in particular the indirect interferences of each element, were studied. A method to distinguish the interference between each other periodic elements in element periodic table was put forward. The measuring conditions and existence were mainly investigated, and the selected background position as well as corrected spectral overlap for the trace elements were also discussed. It was found that the indirect spectral overlap line was the same important as direct spectral overlap line. Due to inducing the effect of indirect spectral overlap, some elements jlike Bi, Sn, W which do not need analysis were also added to the elements channel. The relative standard deviation (RSD) was in the range of 0.01% to 5.45% except three elements Mo, Cs and Ta. The detection limits, precisions and accuracies for most elements using this method can meet the requirements of sample analysis in clay mineral species.

  9. The role of clay minerals in the reduction of nitrate in groundwater by zero-valent iron.

    Science.gov (United States)

    Cho, Dong-Wan; Chon, Chul-Min; Jeon, Byong-Hun; Kim, Yongje; Khan, Moonis Ali; Song, Hocheol

    2010-10-01

    Bench-scale batch experiments were performed to investigate the feasibility of using different types of clay minerals (bentonite, fuller's earth, and biotite) with zero-valent iron for their potential utility in enhancing nitrate reduction and ammonium control. Kinetics experiments performed with deionized water (DW) and groundwater (GW) revealed nitrate reduction by Fe(0) proceeded at significantly faster rate in GW than in DW, and such a difference was attributed to the formation of green rust in GW. The amendment of the minerals at the dose of 25 g L(-1) in Fe(0) reaction in GW resulted in approximately 41%, 43%, and 33% more removal of nitrate in 64 h reaction for bentonite, fuller's earth, and biotite, respectively, compared to Fe(0) alone reaction. The presumed role of the minerals in the rate enhancement was to provide sites for the formation of surface bound green rust. Bentonite and fuller's earth also effectively removed ammonium produced from nitrate reduction by adsorption, with the removal efficiencies significantly increased with the increase in mineral dose above 5:1 Fe(0) to mineral mass ratio. Such a removal of ammonium was not observed for biotite, presumably due to its lack of swelling property. Equilibrium adsorption experiments indicated bentonite and fuller's earth had maximum ammonium adsorption capacity of 5.6 and 2.1 mg g(-1), respectively.

  10. Distribution of clay minerals in marine sediments off Chennai, Bay of Bengal, India:Indicators of sediment sources and transport processes

    Institute of Scientific and Technical Information of China (English)

    Subramanian VEERASINGAM; Ramdoss VENKATACHALAPATHY; Thirunavukkarasu RAMKUMAR

    2014-01-01

    Clay mineralogy, texture size and statistical analyses were carried out on surface sediments from the continental shelf of Chennai, Bay of Bengal, India. The purpose of this study is to characterize the clay mineral distribution and its relation to the hydrodynamics off Chennai to identify the sources and transport pathways of the marine sediments. Characterization of clay minerals in coastal sediments by Fourier Transform Infrared (FTIR) spectroscopy has provided the association of quartz, feldspar, kaolinite, chlorite, illite and iron oxides (magnetite and hematite) derived from river catchments and coastal erosion. Kaolinite, chlorite, illite, iron oxides, and organic matter are the dominant minerals in Cooum, and Adayar region. High quartz and feldspar zones were identified in Marina, which are being confined the sand zone and paralleling the coast. The strong relationships among the wave energy density, sand, quartz and carbonate revealed that wave induced littoral drift system play a dominant role in transportation and deposition of sediments in the Chennai coast. The sediment texture and minerals data are in agreement well with the previous results of hydrodynamics and littoral drift models in this region. Multivariate statistical analyses (correlation, cluster and factor analyses) were carried out and obtained results suggested that clay minerals and organic matter are trapped in silt and clay particles, whereas quartz, feldspar and carbonate are associated with sand particles. Results of sediment sources and transport processes from this study will be useful to predict the fate of the pollutants released from land or the potential change in sediment delivery to coastal areas.

  11. Structural Investigation of Alkali Activated Clay Minerals for Application in Water Treatment Systems

    Science.gov (United States)

    Bumanis, G.; Bajare, D.; Dembovska, L.

    2015-11-01

    Alkali activation technology can be applied for a wide range of alumo-silicates to produce innovative materials with various areas of application. Most researches focuse on the application of alumo-silicate materials in building industry as cement binder replacement to produce mortar and concrete [1]. However, alkali activation technology offers high potential also in biotechnologies [2]. In the processes where certain pH level, especially alkaline environment, must be ensured, alkali activated materials can be applied. One of such fields is water treatment systems where high level pH (up to pH 10.5) ensures efficient removal of water pollutants such as manganese [3]. Previous investigations had shown that alkali activation technology can be applied to calcined clay powder and aluminium scrap recycling waste as a foam forming agent to create porous alkali activated materials. This investigation focuses on the structural investigation of calcined kaolin and illite clay alkali activation processes. Chemical and mineralogical composition of both clays were determined and structural investigation of alkali activated materials was made by using XRD, DTA, FTIR analysis; the microstructure of hardened specimens was observed by SEM. Physical properties of the obtained material were determined. Investigation indicates the essential role of chemical composition of the clay used in the alkali activation process, and potential use of the obtained material in water treatment systems.

  12. Suitability of the methylene blue test for determination of cation exchange capacity of clay minerals related to ammonium acetate method

    Science.gov (United States)

    Milošević, Maja; Logar, Mihovil; Dojčinović, Biljana; Erić, Suzana

    2015-04-01

    Cation exchange capacity (CEC) represents one of the most important parameters of clay minerals which reflects their ability to exchange cations with liquid phases in near contact. Measurement of CEC is used for characterizing sample plasticity, adsorbing and swelling properties which later define their usage in industrial purposes. Several methods have been developed over the years for determination of layer charge, charge density, charge distribution, etc. and have been published in numerous papers (Czimerova et al., 2006; Yukselen and Kaya, 2008). The main goal of present study is comparison of suitability of more recent method - methylene blue test in regard to older method - ammonium acetate for determination of CEC. For this study, we selected one montmorillonite clay (Bogovina, Serbia) and two mainly kaolinite clays (Miličinica, Serbia). Chemicals used for CEC determinations were solution of methylene blue (MB)(14*10-6M/ml) and ammonium acetate (AA) solution (1M). The obtained results are showing generally lower values in case of MB method. The main difference is due to molecular aggregation of MB on the clay surface. AA method is highly sensitive to the presence of CaO. Release of Ca ion from the sample into the solution can limit the saturation of exchange sites by the ammonium ion. This is clearly visible in case of montmorillonite clay. Fe2+ and Mg ions are difficult to move by the ammonium ion because of their ion radius, but in case of MB molecule there is no such restriction in removing them from the exchange sites. MB solution, even in a low concentration (2*10-6M/ml), is showing preferable results in moving the ions from their positions which is already visible after adding a small quantity of solution (25cm3). Both MB-titration and MB-spot test yield similar results and are much simpler methods than AA and they also give other information such as specific surface area (external and internal) whereas AA method only provides information about

  13. Time and pH-dependent sorption of the veterinary antimicrobial sulfathiazole to clay minerals and ferrihydrite.

    Science.gov (United States)

    Kahle, Maren; Stamm, Christian

    2007-07-01

    Substantial amounts of sulfonamides, ionizable, polar veterinary antimicrobials, may reach the environment by spreading of manure. Sorption to soils and sediments is a crucial but not sufficiently understood process influencing the environmental fate of sulfonamides. Therefore, we investigated sorption of sulfathiazole to clay minerals (montmorillonite, illite) and ferrihydrite for varying pH values and two contact times (1d, 14 d) under sterile conditions. Results were compared to sulfathiazole sorption to organic sorbents. Sulfathiazole sorption to inorganic sorbents exhibited pronounced pH dependence consistent with sorbate speciation and sorbent charge properties. While sulfathiazole cations were most important for sorption to clay minerals, followed by neutral species, ferrihydrite was a specific anion sorbent, showing significant sorption only between pH 5.5-7. Experiments revealed a substantial increase of sorption with time for ferrihydrite (pH 5.5-7) and illite (pHsorbents was more than an order of magnitude lower than to organic sorbents. This implies that in many topsoils and sediments inorganic sorbents play a minor role. Our results highlight the need to account for contact time and speciation when predicting sulfonamide sorption in the environment.

  14. Adsorption mechanisms of emerging micro-pollutants with a clay mineral: Case of tramadol and doxepine pharmaceutical products.

    Science.gov (United States)

    Thiebault, Thomas; Guégan, Régis; Boussafir, Mohammed

    2015-09-01

    A sodium exchanged smectite clay mineral (Mt) was used as geo-sorbent for the adsorption of tramadol and doxepin: two pharmaceutical products (PPs) defined as emerging pollutants due to their presence at significant concentration in numerous water compartments. The adsorption isotherms for both the temperatures of 20 and 40°C and the derived data determined through the fitting procedure by using Langmuir, Freundlich and Dubinin-Radushkevich equation models explicitly pointed out that the sorption of both tramadol and doxepin is mainly driven by electrostatic interaction. The studied PPs are intercalated in a monolayer arrangement within the interlayer space through a cation exchange in stoichiometric proportion with the Na(+) cations leading to adsorbed PPs amounts that match the cation exchange capacity (CEC) of Mt. Due to their hydrophobic character, additional doxepin molecules could be adsorbed by weak molecular interaction driving to an increase of the adsorbed amount beyond the CEC at low temperature (20°C). The confinement of PPs within the interlayer space of Mt confirms the use of clay minerals as potential material for the wastewater treatment as well as it drives to an amorphous or glassy state, which can find echo in biopharmaceutical applications for a controlled release of PPs.

  15. Equilibrium, kinetic and thermodynamic studies on the adsorption of the toxins of Bacillus thuringiensis subsp. kurstaki by clay minerals

    Energy Technology Data Exchange (ETDEWEB)

    Fu Qingling; Deng Yali; Li Huishu; Liu Jie [Key Laboratory of Subtropical Agricultural Resource and Environment, Ministry of Agriculture, Huazhong Agricultural University, Wuhan, 430070 (China); Hu Hongqing, E-mail: hqhu@mail.hzau.edu.cn [Key Laboratory of Subtropical Agricultural Resource and Environment, Ministry of Agriculture, Huazhong Agricultural University, Wuhan, 430070 (China); Chen Shouwen [Key Laboratory of Subtropical Agricultural Resource and Environment, Ministry of Agriculture, Huazhong Agricultural University, Wuhan, 430070 (China); Sa Tongmin [Department of Agricultural Chemistry, College of Agriculture, Chungbuk National University, Cheongju, 361-763 (Korea, Republic of)

    2009-02-01

    The persistence of Bacillus thuringiensis (Bt) toxins in soil is further enhanced through association with soil particles. Such persistence may improve the effectiveness of controlling target pests, but impose a hazard to non-target organisms in soil ecosystems. In this study, the equilibrium adsorption of the Bt toxin by four clay minerals (montmorillonite, kaolinite, goethite, and silicon dioxide) was investigated, and the kinetic and thermodynamic parameters were calculated. The results showed that Bt toxin could be adsorbed easily by minerals, and the adsorption was much easier at low temperature than at high temperature at the initial concentration varying from 0 to 1000 mg L{sup -1}. The adsorption fitted well to both Langmuir and Freundlich isotherm models, but the Freundlich equation was more suitable. The pseudo-second-order (PSO) was the best application model to describe the adsorption kinetic. The adsorption process appeared to be controlled by chemical process, and the intra-particle diffusion was not the only rate-controlling step. The negative standard free energy ({Delta}{sub r}G{sub m}{sup {theta}}) values of the adsorption indicated that the adsorption of the Bt toxin by the minerals was spontaneous, and the changes of the standard enthalpy ({Delta}{sub r}H{sub m}{sup {theta}}) showed that the adsorption of the Bt toxin by montmorillonite was endothermic while the adsorption by the other three minerals was exothermic.

  16. Equilibrium, kinetic and thermodynamic studies on the adsorption of the toxins of Bacillus thuringiensis subsp. kurstaki by clay minerals

    Science.gov (United States)

    Fu, Qingling; Deng, Yali; Li, Huishu; Liu, Jie; Hu, Hongqing; Chen, Shouwen; Sa, Tongmin

    2009-02-01

    The persistence of Bacillus thuringiensis ( Bt) toxins in soil is further enhanced through association with soil particles. Such persistence may improve the effectiveness of controlling target pests, but impose a hazard to non-target organisms in soil ecosystems. In this study, the equilibrium adsorption of the Bt toxin by four clay minerals (montmorillonite, kaolinite, goethite, and silicon dioxide) was investigated, and the kinetic and thermodynamic parameters were calculated. The results showed that Bt toxin could be adsorbed easily by minerals, and the adsorption was much easier at low temperature than at high temperature at the initial concentration varying from 0 to 1000 mg L -1. The adsorption fitted well to both Langmuir and Freundlich isotherm models, but the Freundlich equation was more suitable. The pseudo-second-order (PSO) was the best application model to describe the adsorption kinetic. The adsorption process appeared to be controlled by chemical process, and the intra-particle diffusion was not the only rate-controlling step. The negative standard free energy ( ΔGmθr) values of the adsorption indicated that the adsorption of the Bt toxin by the minerals was spontaneous, and the changes of the standard enthalpy ( ΔHmθr) showed that the adsorption of the Bt toxin by montmorillonite was endothermic while the adsorption by the other three minerals was exothermic.

  17. The 1.7- to 4.2-micron spectrum of asteroid 1 Ceres - Evidence for structural water in clay minerals

    Science.gov (United States)

    Lebofsky, L. A.; Feierberg, M. A.; Larson, H. P.; Johnson, J. R.; Tokunaga, A. T.

    1981-01-01

    A high-resolution Fourier spectrum (1.7-3.5 microns) and medium-resolution spectrophotometry (2.7-4.2 microns) were obtained for Asteroid 1 Ceres. The presence of the 3-micron absorption feature due to water of hydration was confirmed. The 3-micron feature is compared with the 3-micron bands due to water of hydration in clays and salts. It is concluded that the spectrum of Ceres shows a strong absorption at 2.7-2.8 microns due to structural OH groups in clay minerals. The dominant minerals on the surface of Ceres are therefore hydrated clay minerals structurally similar to terrestrial montmorillonites. There is also a narrow absorption feature at 3.1 microns which is attributable to a very small amount of water ice on Ceres. This is the first evidence for ice on the surface of an asteroid.

  18. Estimating mineral abundances of clay and gypsum mixtures using radiative transfer models applied to visible-near infrared reflectance spectra

    Science.gov (United States)

    Robertson, K. M.; Milliken, R. E.; Li, S.

    2016-10-01

    Quantitative mineral abundances of lab derived clay-gypsum mixtures were estimated using a revised Hapke VIS-NIR and Shkuratov radiative transfer model. Montmorillonite-gypsum mixtures were used to test the effectiveness of the model in distinguishing between subtle differences in minor absorption features that are diagnostic of mineralogy in the presence of strong H2O absorptions that are not always diagnostic of distinct phases or mineral abundance. The optical constants (k-values) for both endmembers were determined from bi-directional reflectance spectra measured in RELAB as well as on an ASD FieldSpec3 in a controlled laboratory setting. Multiple size fractions were measured in order to derive a single k-value from optimization of the optical path length in the radiative transfer models. It is shown that with careful experimental conditions, optical constants can be accurately determined from powdered samples using a field spectrometer, consistent with previous studies. Variability in the montmorillonite hydration level increased the uncertainties in the derived k-values, but estimated modal abundances for the mixtures were still within 5% of the measured values. Results suggest that the Hapke model works well in distinguishing between hydrated phases that have overlapping H2O absorptions and it is able to detect gypsum and montmorillonite in these simple mixtures where they are present at levels of ∼10%. Care must be taken however to derive k-values from a sample with appropriate H2O content relative to the modeled spectra. These initial results are promising for the potential quantitative analysis of orbital remote sensing data of hydrated minerals, including more complex clay and sulfate assemblages such as mudstones examined by the Curiosity rover in Gale crater.

  19. The protective effect of clay minerals against damage to adsorbed DNA induced by cadmium and mercury.

    Science.gov (United States)

    Hou, Yakun; Wu, Pingxiao; Zhu, Nengwu

    2014-01-01

    The adsorption of Salmon Sperm DNA on three kinds of raw clay (rectorite, montmorillonite and sericite) was investigated as a function of pH, ionic strength and the concentrations of DNA and phosphate ions in solution. The DNA adsorption was reduced in the following order: rectorite>montmorillonite>sericite. Based on these findings, there is a strong evidence that the mechanisms for DNA adsorption on clay involve electrostatic forces, cation bridging and ligand exchange. Cyclic voltammetry (CV) and UV-vis absorption and fluorescence spectroscopy were used to compare the properties of unbound DNA and the absorbed DNA on rectorite, both in the absence and presence of Cd(2+) and Hg(2+) inaqueous solutions. The interaction of heavy metals with the unbound DNA was evidenced by the disappearance of reduction peaks in CV, a small bathochromic shift in UV-vis spectroscopy and an incomplete quenching in the emission spectra. Such changes were not observed in the DNA-rectorite hybrids, which is evidence that adsorption on the clay can reduce the extent of the DNA damage caused by heavy metals. Therefore, in these experience the rectorite played an important role in protecting DNA against Cd(2+) and Hg(2+) induced damage.

  20. Effect of pH on the heavy metal-clay mineral interaction

    Energy Technology Data Exchange (ETDEWEB)

    Altyn, O.; Oezbelge, H.O.; Dogu, T.; Oezbelge, T.A. [Middle East Technical Univ., Ankara (Turkey)

    1997-12-31

    Adsorption and ion exchange of Pb and Cd on the surface of kaolinite and montmorillonite were studied with a strong emphasis on the pH values of solutions containing heavy metal ions. The pH range studied was 2.5 - 9. For kaolinite at a clay/solution ratio of 1/10 (w/w), Pb removal changes from 20 to 30% for an initial Pb concentration of 1640 ppm, and Cd removal changes from 10 to 20% for an initial Cd concentration of 1809 ppm. Due to its high exchange capacity, montmorillonite can remove more heavy metal than kaolinite. Removal rates for montmorillonite can reach up to 90% for both Pb and Cd. In the pH range of 3-6, there is a plateau for the removal rates. At pH values higher than 6, removal seems to increase artificially due to the precipitation of heavy metals. Under similar conditions for both clays, the rate of removal of Pb is always higher than that of Cd. As the pH value decreases for montmorillonite, there is a strong tendency for decreased surface area and swelling, as indicated by BET surface area measurements, adsorbed layer thickness and pore size distribution data. In the range of pH values studied, X-ray diffraction analysis showed the appearance of a characteristic (001) peak for montmorillonite, indicating that the crystalline structure of the clay was intact during the experiments.

  1. Investigations of the use of clay minerals and prussian blue in reducing the transfer of dietary radiocaesium to milk.

    Science.gov (United States)

    Unsworth, E F; Pearce, J; McMurray, C H; Moss, B W; Gordon, F J; Rice, D

    1989-09-01

    Two experiments were performed with lactating dairy cattle to assess the efficacy of clay minerals and Prussian Blue (AFCF form) in controlling the transfer of dietary radiocaesium to milk. In Experiment 1, bentonite was included in the diet at 0, 300, 600 and 900 g d-1 and the transfer of radiocaesium from silage to milk was determined. Bentonite inclusion significantly (P less than 0.001) depressed the transfer of radiocaesium to milk with no benefit in increasing the dietary inclusion above 600 g d-1 when a 73% reduction was observed. In Experiment 2, the effectiveness of bentonite (300 g d-1), clinoptilolite (300 g d-1) and Prussian Blue (3 g d-1) as dietary additives was compared. All treatments significantly (P less than 0.001) depressed the transfer of dietary radiocaesium to milk. Clinoptilolite was less effective than bentonite and both treatments were considerably less effective than Prussian Blue, the reductions being 35%, 62% and 85% respectively.

  2. Experimental Study of the Selective Adsorption of Heavy Metals onto Clay Minerals

    Institute of Scientific and Technical Information of China (English)

    何宏平; 郭九皋; 等

    2000-01-01

    The interaction between minerals and heavy metals has been a hot object of study in environmental science,mineralogy and soil science,Through the selective adsorption experiment of Ca-montomorillonite,illite and kaolinite to Cu2+,Pb2+,Zn2+,Cd2+,and Cr3+ ions at certain conditions,it could be concluded that Cr3+ is most effectively sorbed by all the three minerals.Also,it can be found that Pb2+ shows a strong affinity for illite and kaolinite while cu2+ for montmorillonite .Based on the adsorption experiment at varying pH of solution,it can be found that the amount of heavy etals sorbed by minerals increases with increasing pH of the solution.

  3. Mineral potential of clays that cover the gypsum deposits in Araripina-PE region; Potencial mineral das argilas que recobrem as jazidas de gipsita na regiao de Araripina-PE

    Energy Technology Data Exchange (ETDEWEB)

    Lira, B.B.; Anjos, I.F. dos, E-mail: belarminolira@ct.ufpb.br [Universidade Federal da Paraiba (CT/UFPB), PB (Brazil); Rego, S.A.B.C. [Universidade Federal de Pernambuco (PGEM/DEMEC/UFPE), PE (Brazil)

    2011-07-01

    In the present work the applicability of the clays that cover the deposits of Gypsum Plaster in the region of Araripina - PE for use as the ceramic pigments and for bricks production in the red ceramic industry was analyzed. The clay minerals contained the illite, kaolinite and smectite, with high proportion of the last one. The possibility of industrial application of this mineral clay is considerable; however, the mining industries that mine and process the gypsum in the region do not take the clays into account as the potential mineral. In general, industries use the clay minerals in manufacturing processes or as key raw materials, or as the alternatives for some kinds of the chemical processing industries. This paper aims to highlight the potential of materials that cover the deposits of gypsum in reference. The material sampled from different deposit layers was characterized and the physical treatment of ore was applied. The results showed that the material analyzed can be used in various kinds of industry, such as the production of natural ceramic pigments. (author)

  4. Clay minerals in primitive meteorites and interplanetary dust 2. Smectites and micas

    Science.gov (United States)

    Keller, L. P.; Zolensky, M. E.

    1991-01-01

    The classification is briefly summarized of stony meteorites and cosmic dust, and the mineralogy and chemistry is described of serpentine group minerals. The occurrence of smectites and micas in extraterrestrial materials is examined. The characterization of fine grained minerals in meteorites and IDPs relies heavily on electron beam instruments, especially the transmission electron microscope (TEM). Typically, phyllosilicates are identified by a combination of high resolution imaging of basal spacings, electron diffraction, and chemical analysis. Smectites can be difficult to differentiate from micas because the smectites lose their interlayer water and the interlayer partly collapse in the high vacuum of the TEM.

  5. Chemical and physical transformations of aluminosilicate clay minerals due to acid treatment and consequences for heterogeneous ice nucleation.

    Science.gov (United States)

    Sihvonen, Sarah K; Schill, Gregory P; Lyktey, Nicholas A; Veghte, Daniel P; Tolbert, Margaret A; Freedman, Miriam Arak

    2014-09-25

    Mineral dust aerosol is one of the largest contributors to global ice nuclei, but physical and chemical processing of dust during atmospheric transport can alter its ice nucleation activity. In particular, several recent studies have noted that sulfuric and nitric acids inhibit heterogeneous ice nucleation in the regime below liquid water saturation in aluminosilicate clay minerals. We have exposed kaolinite, KGa-1b and KGa-2, and montmorillonite, STx-1b and SWy-2, to aqueous sulfuric and nitric acid to determine the physical and chemical changes that are responsible for the observed deactivation. To characterize the changes to the samples upon acid treatment, we use X-ray diffraction, transmission electron microscopy, and inductively coupled plasma-atomic emission spectroscopy. We find that the reaction of kaolinite and montmorillonite with aqueous sulfuric acid results in the formation of hydrated aluminum sulfate. In addition, sulfuric and nitric acids induce large structural changes in montmorillonite. We additionally report the supersaturation with respect to ice required for the onset of ice nucleation for these acid-treated species. On the basis of lattice spacing arguments, we explain how the chemical and physical changes observed upon acid treatment could lead to the observed reduction in ice nucleation activity.

  6. Oligomerization of glycine on clay mineral surface and implication to oligin of life under seafloor hydrothermal conditions

    Science.gov (United States)

    Fuchida, S.; Masuda, H.

    2012-12-01

    The sediments at hydrothermal and/or various parts of the crust has been believed to be good environments to proceed the chemical evolution of life precursor, since minerals promoted oligomerization of amino acids, sugars and lipids on the primitive earth. In this study, the thermal behaviors of glycine (Gly), the simplest amino acid, adsorbed on montmorillonite was observed to evaluate the role of clay minerals and water on the oligomerization under thermal condition of sediments. Gly was adsorbed on montmorillonite was heated at 150 degree C for 3-288 hrs under dry and wet condition. In the latter case, 10 - 60% water was added in the system. The amount of Gly monomer remaining in the montmorillonite exponentially decreased with time; 46% Gly remained in the montmorillonite under dry condition and 74% under wet condition after 288 hrs. The Gly monomer was more stable under hydrothermal condition than dry thermal condtion. FT-IR analysis suggested that the Gly was intercalated in the montmorillonite via hydrogen bond, which is likely to promote to stabilize Gly, between amino group of the Gly and silanol group of the montmorillonite. On the contrast, the yields of peptides were low on motmorillonite after heated under the wet condition: the amounts of glycilglycine (Gly-Gly) and diketopiperazine (DKP) are 0.8% and 0.9%, respectively. The amounts of DKP and GlyGly are 12.9% and 4.8% after heated under the dry condtion. Excessive water would promote to hydrolyze synthesized peptides. New band at 1671cm-1 by FT-IR implies that DKP was condensed on the montmorillonite. DKP was not formed without montmorillonite under the dry condition, although peptide formation is theoretically favorable. Water molecules including in the montmorillonite would act as proton transfer to promote the peptide formation. The peptide formation would be more proceeded under a little wet condition than completely dry condition. Results of this study suggested that deep sediments, where

  7. Bioavailability of iron in geophagic earths and clay minerals, and their effect on dietary iron absorption using an in vitro digestion/Caco-2 cell model.

    Science.gov (United States)

    Seim, Gretchen L; Ahn, Cedric I; Bodis, Mary S; Luwedde, Flavia; Miller, Dennis D; Hillier, Stephen; Tako, Elad; Glahn, Raymond P; Young, Sera L

    2013-08-01

    Geophagy, the deliberate consumption of earth, is strongly associated with iron (Fe) deficiency. It has been proposed that geophagy may be practiced as a means to improve Fe status by increasing Fe intakes and, conversely, that geophagy may cause Fe deficiency by inhibiting Fe absorption. We tested these hypotheses by measuring Fe concentration and relative bioavailable Fe content of 12 samples of geophagic earth and 4 samples of pure clay minerals. Further, we assessed the impact of these samples on the bioavailability of Fe from an Fe-rich test meal (cooked white beans, WB). Fe concentrations were measured with inductively coupled plasma atomic emission spectroscopy. Fe bioavailability was determined using an in vitro digestion/Caco-2 cell model in which ferritin formation was used as an index of Fe bioavailability. Geophagic earth and clay mineral samples were evaluated with this model, both alone and in combination with WB (1 : 16 ratio, sample : WB). Median Fe concentration of the geophagic earth was 3485 (IQR 2462, 14 ,571) μg g⁻¹ and mean Fe concentration in the clay minerals was 2791 (±1782) μg g⁻¹. All specimens had Fe concentrations significantly higher (p ≤ 0.005) than the Fe concentration of WB (77 μg g⁻¹). Ferritin formation (i.e. Fe uptake) in cells exposed to geophagic earths and clay minerals was significantly lower than in cells exposed to WB (p ≤ 0.05) and Fe uptake responses of 11 of the 16 samples were not significantly different from the blank, indicating no bioavailable Fe. When samples were combined with WB, 5 of 16 had mean ferritin levels that were significantly lower (p ≤ 0.05, one tail) than the WB alone, indicating that the samples inhibited Fe uptake from the WB. None of the ferritin responses of cells exposed to both WB and earth/clay were significantly higher than WB alone. Thus, although geophagic earths and mineral clays are high in total Fe, very little of this Fe is bioavailable. Further, some

  8. Antibiotic eluting clay mineral (Laponite®) for wound healing application: an in vitro study.

    Science.gov (United States)

    Ghadiri, M; Chrzanowski, W; Rohanizadeh, R

    2014-11-01

    Different materials in form of sponge, hydrogel and film have been developed and formulated for treating and dressing burn wounds. In this study, the potential of Laponite, a gel forming clay, in combination with an antimicrobial agent (mafenide), as a wound dressing material was tested in vitro. Laponite/mafenide (Lap/Maf) hydrogel was formulated in three different ratios of Lap/Maf 1:1, 1:2, 1:3. Laponite/mafenide/alginate (Lap/Maf/Alg) film was also formulated by combining Lap/Maf gel (1:1) with alginate. Intercalation rate of mafenide into the layers of Laponite nanoparticles and physico-chemical properties, including wound dressing characteristics of materials were studied using various analytical methods. Furthermore, the degradation of materials and the release profile of mafenide were investigated in simulated wound exudates fluid and antibacterial effectiveness of the eluted mafenide was tested on a range of bacterial species. The cytotoxicity of materials was also evaluated in skin fibroblast culture. The results showed that mafenide molecules were intercalated between the nano-sized layers of Laponite. The eluted mafenide showed active antibacterial effects against all three tested bacteria. All intercalated mafenide released from Lap/Maf 1:1 and 1:2 gel formulations and nearly 80% release from 1:3 formulation during test period. No significant difference was observed in release profile of mafenide between Lap/Maf/Alg film and Lap/Maf formulations. Wound dressing tests on Lap/Maf/Alg film showed it is a breathable dressing and has capacity to absorb wound exudates. The study showed that prepared Lap/Maf composite has the potential to be used as an antibiotic eluting gel or film for wound healing application. Additionally, Laponite has shown benefits in wound healing processes by releasing Mg(2+) ions and thereby reducing the cytotoxic effect of mafenide on fibroblast cells.

  9. Viscosity and Plasticity of Latvian Illite Clays

    OpenAIRE

    2012-01-01

    Due to viscosity and plasticity, clays and clay minerals are used in civil engineering, pottery and also in cosmetics and medicine as thickening agents and emulsion and suspension stabilizers. The rheological properties of clay suspensions are complex. Mostly it is an interaction between mineral composition, clay particle size and pH value and also depends on clay minerals. Clay-water suspension is non-Newtonian fluid showing thixotropic and pseudoplastic properties. Results showed that plast...

  10. Physical Properties of Latvian Clays

    OpenAIRE

    2012-01-01

    Physical and chemical properties of clays mostly depends on its mineral and chemical composition, particle size and pH value. The mutual influence of these parameters is complex. Illite is the most abundant clay mineral in Latvia and usually used in building materials and pottery. The viscosity and plasticity of Latvian clays from several deposits were investigated and correlated with mineral composition, particle size and pH value. Fractionated and crude clay samples were used. The p...

  11. Effects of Organic Anions on Phosphate Adsorption and Desorption from Variable—Charge Clay Minerals and Soil

    Institute of Scientific and Technical Information of China (English)

    HEZHEN-LI; YUANKE-NENG; 等

    1992-01-01

    Effects of citrate and tartrate on phosphate adsorption and desorption from kaolinite,goethite,amorphous Al-oxide and Ultisol were studied.P adsorption was significantly decreased as the concentration of the organic anions increased from 10-5 to 10-1 M.At 0.1 M and pH 7.0,tartrate decreased P adsorption by 27.6%-50.6% and citrate by 37.9-80.4%,depending on the kinds of adsorbent.Little Al and/or Fe were detected in the equilibrium solutions,even at the highest concentration of the organic anions.Effects of the organic anions on phosphate adsorption follow essentially the competitive adsorption mechanism.The selectivity coefficients for competitive adsorption can be used to compare the effectiveness of different organic anions in reducing P adsorption under given gonditions. Phosphate desorption was increased by 3 to 100 times in the presence of 0.001 M citrate or tartrate compared to that in 0.02 M KCl solution alone.However,for all the soil and clay minerals studied the amount of P desorbed by citrate or tartrate was generally lower than or close to that of isotopically exchangeable P.The effect of organic anions on phosphate desorption arises primarily from ligand exchange.

  12. Effect of iron oxide coatings on zinc sorption mechanisms at the clay-mineral/water interface.

    Science.gov (United States)

    Nachtegaal, Maarten; Sparks, Donald L

    2004-08-01

    Oxide surface coatings are ubiquitous in the environment, but their effect on the intrinsic metal uptake mechanism by the underlying mineral surface is poorly understood. In this study, the zinc (Zn) sorption complexes formed at the kaolinite, goethite, and goethite-coated kaolinite surfaces, were systematically studied as a function of pH, aging time, surface loading, and the extent of goethite coating, using extended X-ray absorption fine structure (EXAFS) spectroscopy. At pH 5.0, Zn partitioned to all sorbents by specific chemical binding to hydroxyl surface sites. At pH 7.0, the dominant sorption mechanism changed with reaction time. At the kaolinite surface, Zn was incorporated into a mixed metal Zn-Al layered double hydroxide (LDH). At the goethite surface, Zn initially formed a monodentate inner-sphere adsorption complex, with typical Zn-Fe distances of 3.18 A. However, with increasing reaction time, the major Zn sorption mechanism shifted to the formation of a zinc hydroxide surface precipitate, with characteristic Zn-Zn bond distances of 3.07 A. At the goethite-coated kaolinite surface, Zn initially bonded to FeOH groups of the goethite coating. With increasing aging time however, the inclusion of Zn into a mixed Zn-Al LDH took over as the dominant sorption mechanism. These results suggest that the formation of a precipitate phase at the kaolinite surface is thermodynamically favored over adsorption to the goethite coating. These findings show that the formation of Zn precipitates, similar in structure to brucite, at the pristine kaolinite, goethite, and goethite-coated kaolinite surfaces at near neutral pH and over extended reaction times is an important attenuation mechanism of metal contaminants in the environment.

  13. Adsorption of dissolved aluminum on sapphire-c and kaolinite: implications for points of zero charge of clay minerals.

    Science.gov (United States)

    Lützenkirchen, Johannes; Abdelmonem, Ahmed; Weerasooriya, Rohan; Heberling, Frank; Metz, Volker; Marsac, Remi

    2014-01-01

    We have studied the impact of dissolved aluminum on interfacial properties of two aluminum bearing minerals, corundum and kaolinite. The effect of intentionally adding dissolved aluminum on electrokinetic potential of basal plane surfaces of sapphire was studied by streaming potential measurements as a function of pH and was complemented by a second harmonic generation (SHG) study at pH 6. The electrokinetic data show a similar trend as the SHG data, suggesting that the SHG electric field correlates to zeta-potential. A comparable study was carried out on kaolinite particles. In this case electrophoretic mobility was measured as a function of pH. In both systems the addition of dissolved aluminum caused significant changes in the charging behavior. The isoelectric point consistently shifted to higher pH values, the extent of the shift depending on the amount of aluminum present or added. The experimental results imply that published isoelectric points of clay minerals may have been affected by this phenomenon. The presence of dissolved aluminum in experimental studies may be caused by particular pre-treatment methods (such as washing in acids and subsequent adsorption of dissolved aluminum) or even simply by starting a series of measurements from extreme pH (causing dissolution), and subsequently varying the pH in the very same batch. This results in interactions of dissolved aluminum with the target surface. A possible interpretation of the experimental results could be that at low aluminum concentrations adatoms of aluminum (we will refer to adsorbed mineral constituents as adatoms) can form at the sapphire basal plane, which can be rather easily removed. Simultaneously, once the surface has been exposed to sufficiently high aluminum concentration, a visible change of the surface is seen by AFM which is attributed to a surface precipitate that cannot be removed under the conditions employed in the current study. In conclusion, whenever pre-treatment or the

  14. Frequency fraction and spatial distribution of clay minerals detection by sub-pixel classification of ASTER data, case study, Esteghlal mine of Abadeh

    Directory of Open Access Journals (Sweden)

    Majid Hashemi Tangestani

    2010-05-01

    Full Text Available Esteghlal fireclay mine, northern Abadeh, with dominant composition of kaolinite and pyrophyllite, and annual production of over a million tons, is one of the largest sedimentary deposits in Iran. Linear Spectral Unmixing (LSU and Mixture Tuned Matched Filtering (MTMF processes were applied on the VNIR + SWIR dataset of ASTER for identifying the frequency fraction and distribution of clay minerals in this mine. Sub-pixel frequency assessment of ASTER data showed that distribution of pixels with higher fractions belong to the kaolinite and pyrophyllite, outcropped in two different parts of the mine. Comparison of LSU and MTMF output results showed that MTMF is more reliable to determining the relative fraction of clay minerals at the study area.

  15. Study on clay minerals in Paleozoic reservoirs in the Huanghua Depression%黄骅坳陷上古生界储层粘土矿物研究

    Institute of Scientific and Technical Information of China (English)

    张晨; 苗建宇; 宋红霞; 王静茹

    2012-01-01

    通过对黄骅坳陷上古生界储层78个样品的X衍射分析、扫描电镜和铸体薄片观察指明其储层中粘土矿物以伊利石、伊/蒙间层为主,含少量自生高岭石及绿泥石,产状以薄膜式、搭桥式为主.随深度增加伊利石含量上升、伊/蒙间层比增大,致使储层孔、渗减小.与压汞测试结果进行对比后确定粘土矿物与压汞曲线间存在三种典型对照关系.同时,粘土矿物组合暗示本区为干旱盐湖的古环境.全区成岩环境均为碱性,仅在油藏附近表现为碱-酸-碱的变化过程.%X - ray diffraction, scanning electron microscopy and casting thin observation of 78 samples from Paleozoic reservoirs in the Huanghua Depression indicate that the main clay mineral are mainly as follow illite, illite - smectite and there are a few authigenic kaolinite and chlorite and the clay mineral appear as film - like style and bridge type. Illite content and I/S increase with depth increasing, which lead to the decrease of permeability of reservoir pore. Three typical of the relationship between the mercury curves and clay minerals were obtained by taking pressured - mercury testing. The clay mineral assemblages imply that this area' s ancient environment was dry - salt lake; the regional dia-genetic environment were alkaline; the environment being close to oil reservoir showed individually alkali - acid - alkali process.

  16. Pre-treatment of Used-Cooking Oil as Feed Stocks of Biodiesel Production by Using Activated Carbon and Clay Minerals

    Directory of Open Access Journals (Sweden)

    Rudy Syah Putra

    2014-02-01

    Full Text Available Many low-cost feedstock i.e. used-cooking oil (UCO for the production of biodiesel fuel (BDF has contained a large amount of water and high proportion of free fatty acids (FFAs. Therefore, a pre-treatment process to reduce the water content (<0.1 wt.% and FFAs (<2.0 wt.% were necessary in order to avoid an undesirable side reactions, such as saponification, which could lead to serious problem of product separation and low fatty acid methyl ester (FAME yield. . In this study, a pre-treatment process of used cooking oil as a feedstock for the production of BDF by using various adsorbents such as Activated Carbon (AC and various clay minerals, for example Smectite (S, Bentonite (B, Kaolinite (K, and Powdered Earthenware (PE were evaluated. The oil obtained from pre-treatment was compared with oil without pre-treatment process. In this study, we reported a basic difference in material ability to the oil, depending on the adsorption condition with respect to the physico-chemical parameters, e.g. refractive index (R, density (ρ, FFAs, and water content (W. The results showed that the water content and FFAs in the oil has decreased when using AC as an adsorbent compared with clay minerals. However, the refractive index of oil has similar with the oil without pre-treatment process as well; meanwhile, the density of oil has increased after the pre-treatment process by using clay minerals.

  17. Synergy between polyaniline and OMt clay mineral in Langmuir-Blodgett films for the simultaneous detection of traces of metal ions.

    Science.gov (United States)

    de Barros, Anerise; Ferreira, Mariselma; Constantino, Carlos José Leopoldo; Bortoleto, José Roberto Ribeiro; Ferreira, Marystela

    2015-04-01

    We report on Langmuir-Blodgett (LB) films made with emeraldine salt polyaniline (PAni-ES) and organophilic montmorillonite clay mineral (OMt), where synergy between the components was reached to yield an enhanced performance in detecting trace levels of cadmium (Cd(2+)), lead (Pb(2+)) and copper (Cu(2+)). Detection was carried out using square wave anodic stripping (SWAS) voltammetry with indium tin oxide (ITO) electrodes modified with LB films of PAni-ES/OMt nanocomposite, whose data were compared to those obtained with electrodes coated with neat PAni-ES and neat OMt LB films. The enhanced performance in the nanocomposite may be attributed to the stabilizing and ordering effect promoted by OMt in PAni-ES Langmuir films, which then led to more homogeneous LB films. According to X-ray diffraction data, the stacking of OMt layers was preserved in the LB films and therefore the PAni-ES chains did not cause clay mineral exfoliation. Instead, OMt affected the polaronic state of PAni-ES as indicated in UV-vis, Raman and FTIR spectra, also consistent with the changes observed for the Langmuir films. Taken together these results do indicate that semiconducting polymers and clay minerals may be combined for enhancing the electrical properties of nanostructures for sensing and related applications.

  18. Clay minerals of Pliocene deposits and their potential use for the purification of polluted wastewater in the Sohag area, Egypt

    NARCIS (Netherlands)

    Y. Refaey; B. Jansen; A.H. El-Shater; A.A. El-Haddad; K. Kalbitz

    2015-01-01

    In our study we investigated the clay fraction composition of Pliocene clay deposits in the Sohag area, Egypt. Our goal was to obtain insights into the origin of the deposits, and to assess their potential for use in inexpensive wastewater purification. The rationale for the latter was that in Egypt

  19. Physico-chemical and technological properties of ceramic tiles: Role of clay minerals on as pressed and dried compacts properties

    Directory of Open Access Journals (Sweden)

    Gouzouli N.

    2013-09-01

    Full Text Available Chemical, mineralogical and technological properties of an experimental clay are investigated with the aim to substitute for other clays used at present in factories. Flexural strength distributions of green and dry compacts were analysed and correlated to microstructural features with a view to evaluate their drying ability and their mechanical reliability.

  20. [Effect of Cr (VI) anions on the Cu (II) adsorption behavior of two kinds of clay minerals in single and binary solution].

    Science.gov (United States)

    Liu, Juan-Juan; Liang, Dong-Li; Wu, Xiao-Long; Qu, Guang-Zhou; Qian, Xun

    2014-01-01

    The adsorption of Cu (II) on kaolinite and montmorillonite was investigated through batch adsorption experiment. Several adsorption models were employed to describe the adsorption of Cu (II) on the two clay minerals in single Cu (II) and Cu(II)-Cr (VI) binary solutions, and the impact of solution with various pH values on the adsorption of Cu (II) on the two target mineral clays was investigated in order to explain the environmental chemical behavior of heavy metals in soil and to provide theoretical basis in remediation of multi-element contaminated soil. The results indicated that the adsorption process of Cu (II) on kaolinite and montmorillonite in both single and binary solutions was fast at the beginning and then slowed down. Adsorption equilibrium was observed within 120 min. In both single and binary solutions, pseudo-second-order model (R2 > 0.983) showed the highest agreement with the adsorption of Cu (II) on the two mineral clays, followed by the intra-particle diffusion model and pseudo-first-order model. Both Intra-particle diffusion model and Boyd model illustrated that the film diffusion process was the rate-limiting step, which mainly occurred at the edge and surface of mineral clays. Copper adsorption on kaolinite was well fitted with the Freundlich equation (R2 > 0.971), which could be attributed to the heterogeneity of kaolinite surface with adsorption sites that have different energies of adsorption. Langmuir equation was best fitted with the isotherm for montmorillonite (R2 > 0.983), which indicated that the adsorption was on a single molecular layer or chemisorptions. In both single and binary solutions, the adsorption of Cu (II ) on the two clay minerals first increased and then decreased with the rising of pH values. The maximum adsorption amount was found at pH = 5.0, and was in the order of Qmon. > Qkao. and Q(Single-Cu) > Q(Cu-Cr binary). Cr (VI) in the solution reduced the adsorption of Cu (II), and the minimal influence of Cr (VI) on Cu

  1. Fluid-rock interaction controlling clay-mineral crystallization in quartz-rich rocks and its influence on the seismicity of the Carboneras fault area (SE Spain)

    Science.gov (United States)

    Jimenez-Espinosa, R.; Abad, I.; Jimenez-Millan, J.; Lorite-Herrera, M.

    2009-04-01

    The Carboneras Fault zone is one of the longest fault in the Betic Cordillera (SE Spain) and it would be a good candidate to generate large magnitude earthquakes (Gracia et al., 2006). Seismicity in the region is characterised by low to moderate magnitude events, although large destructive earthquakes have occurred, which reveals significant earthquake and tsunami hazards (Masana et al., 2004). Due to the internal architecture of the fault zone, shear lenses of post-orogenic sediments of Miocene and Pliocene age including marls and sandstones sequences are juxtaposed to the predominant slaty gouges of the Alpine basement. Microcataclasites and gouges of the quartz-rich post-orogenic sediments are also developed as cm- to m-scale bands, allowing the comparison between the deformed materials and their protoliths. Red, yellow and white sandstones and their respective cataclasites can be identified. This communication is concerned with the clay mineral crystallization events in these materials and its possible influence on the seismicity model of the region. The presence of phyllosilicates in fault zones as either neoformed or inherited clays is commonly related with fluid circulation and a mechanically weak fault behaviour (e.g., Wang, 1984). A critical factor for the understanding of the mechanical role of clays in fault rocks is to determine the timing of formation of mineral assemblages and microstructure of fault rocks and protolith. The effects of post-faulting alteration limit inferences about fault behaviour that can be made from exhumed rocks. The Carboneras fault zone provides good opportunities to study mineral processes enhanced by deformation, given that it is located in a region of arid climate and shows outcroppings of quartzitic rocks included in slaty rocks. Combined XRD, optical microscopy and SEM analyses reveal that deformed quartzitic rocks are enriched in phyllosilicates, increasing especially the amount of chlorite. The samples strongly damaged

  2. Biodegradation and adsorption of C1- and C2-phenanthrenes and C1- and C2-dibenzothiophenes in the presence of clay minerals: effect on forensic diagnostic ratios.

    Science.gov (United States)

    Ugochukwu, Uzochukwu C; Head, Ian M; Manning, David A C

    2014-07-01

    The impact of modified montmorillonites on adsorption and biodegradation of crude oil C1-phenanthrenes, C1-dibenzothiophenes, C2-phenanthrenes and C2-dibenzothiophenes was investigated in aqueous clay/oil microcosm experiments with a hydrocarbon degrading microorganism community. Consequently, the effect on C1-dibenzothiophenes/C1-phenanthrenes, C2-dibenzothiophenes/C2-phenanthrenes, 2+3-methyldibenzothiophene/4-methyldibenzothiophene and 1-methyldibenzothiophene/4-methyldibenzothiophene ratios commonly used as diagnostic ratios for oil forensic studies was evaluated. The clay mineral samples were treated to produce acid activated montmorillonite, organomontmorillonite and homoionic montmorillonite which were used in this study. The different clay minerals (modified and unmodified) showed varied degrees of biodegradation and adsorption of the C1-phenanthrenes, C1-dibenzothiophenes, C2-phenanthrenes and C2-dibenzothiophenes. The study indicated that as opposed to biodegradation, adsorption has no effect on the diagnostic ratios. Among the diagnostic ratios reviewed, only C2-dibenzothiophenes/C2-phenanthrenes ratio was neither affected by adsorption nor biodegradation making this ratio very useful in forensic studies of oil spills and oil-oil correlation.

  3. Impact of Long-Term Alfalfa Cropping on Soil Potassium Content and Clay Minerals in a Semi-Arid Loess Soil in China

    Institute of Scientific and Technical Information of China (English)

    LI De-Cheng; B. VELDE; LI Feng-Min; ZHANG Gan-Lin; ZHAO Ming-Song; HUANG Lai-Ming

    2011-01-01

    Alfalfa cropping has been considered an efficient method of increasing soil fertility.Usually nitrogen increase in root nodules is considered to be the major beneficial effect.A 21-year time series (five sampling periods) of alfalfa cultivation plots on a loess soil,initially containing illite and chlorite,in Lanzhou of northwestern China was selected to investigate the relationships among alfalfa cropping,soil potassium (K) content and soil clay minerals.The results indicated that soil K significantly accumulated after cropping,with a peak value at about 15 years,and decreased afterwards.The accumulated K was associated with the K increase in the well-crystallized illite,which was not extracted by the traditional laboratory K extraction methods in assessing bioavailability.The steep decline in soil K content after 15-year cropping was in accord with the observed fertility loss in the alfalfa soil.Plant biomass productivity peaked at near 9 years of culture,whereas soil K and clay minerals continued to increase until cropping for 15 years.This suggested that K increased in the topsoil came from the deep root zone.Thus alfalfa continued to store K in clays even after peak production occurred.Nitrogen did not follow these trends,showing a general decline compared with the native prairie soils that had not been cropped.Therefore,the traditional alfalfa cropping can increase K content in the topsoil.

  4. Colorimetric Humidity and Solvent Recognition Based on a Cation-Exchange Clay Mineral Incorporating Nickel(II)-Chelate Complexes.

    Science.gov (United States)

    Hosokawa, Hitoshi; Mochida, Tomoyuki

    2015-12-01

    Solvatochromic nickel(II) complexes with diketonato and diamine ligands were incorporated into a saponite clay by ion exchange, and their colorimetric humidity- and solvent-recognition properties were investigated. These powders exhibit color change from red to blue-green depending on humidity, and the detection range can be controlled by modifying the metal complex. The humidity response takes advantage of the humidity-dependent water content in clay and the coordination of water molecules to the metal complex in equilibrium. The addition of organic solvents to the powders causes a color change to occur, varying from red to blue-green depending on the donor number of the solvent, thereby enabling solvent recognition. In the clay, the affinity of less sterically hindered complexes to water or solvent molecules is decreased compared with that in solution because the cationic complexes interact with the anionic layers in the clay. Incorporating diethylene glycol into the materials produced thermochromic powders.

  5. CO2-Brine-Iron-bearing Clay Mineral Interactions: Surface Area Changes and Fracture-Filling Potentials in Geologic CO2 Sequestration

    Science.gov (United States)

    Jun, Y.; Hu, Y.

    2011-12-01

    Geologic carbon dioxide sequestration (GCS) is a promising option to reduce anthropogenic CO2 emission from coal-fired power plants. The injected CO2 in GCS sites can induce dissolution of rocks and secondary mineral formation, potentially change the physical properties of the geological formations, and thus influence the transport and injectivity of CO2. However, most of the relevant studies are based on hydrological transport, using simulation models rather than studying actual interfacial chemical reactions. The mechanisms and kinetics of interfacial reactions among supercritical CO2 (scCO2)-saline water-rock surfaces at the molecular scale and their impacts on CO2 leakage have not been well understood. This research investigated the effects of various environmental factors (such as temperature, pressure, salinity, and different metal ion and organic-containing brine) on the dissolution and surface morphological changes of clay minerals. In this work, iron-bearing clay mineral, biotite [K(Mg,Fe)3AlSi3O10(OH,F)2], was used for model clay minerals in potential GCS sites. Both fluid/solid chemistry analysis and interfacial topographic studies were conducted to investigate the dissolution/precipitation on clay mineral surfaces under GCS conditions in high salinity systems. Using atomic force microscopy (AFM) and scanning electron microscopy (SEM), the interfacial surface morphology changes were observed. Shortly after a CO2 pressure of 102 atm is applied at 95oC, in situ pH of solutions was 3.15 ± 0.10. The early intrinsic dissolution rates of biotite were 8.4 ± 2.8 × 10-13 and 11.2 ± 3.0 × 10-13 mol Si m-2s-1 in water and NaCl solution, respectively. At the early stage of reaction, fast growth of fibrous illite on biotite basal planes was observed. After 22-70 h reaction, the biotite basal surface cracked, resulting in illite detaching from the surfaced. Later, the cracked surface layer was released into solution, thus the inner layer was exposed as a renewed

  6. 柴达木盆地粘土矿物特征及其演化%Characteristics and Evolution of the Clay Minerals in Qaida m Basin

    Institute of Scientific and Technical Information of China (English)

    赵东升; 贺鹏; 孔红喜; 郑海鹏; 雷振锋

    2001-01-01

    对柴达木盆地下侏罗系河流夹沼泽相沉积和第三系以来湖相沉积的粘土矿物进行了X射线衍射、电镜等分析和观察,在此基础上讨论粘土矿物的成因,母岩分布和性质、水介质条件和古气候对粘土矿物形成和演化的影响,并通过粘土矿物含量和组合对比,讨论粘土矿物的继承性和粘土矿物组合差异的原因。%The Qaidam basin is a non-marine, petroliferous basin on the northeastern margi n of the Qinghai-Tibetan Plateau, with an area of about 120,000 km2. Almost a ll strata are cropped out except Archaean group. The oil and gas discovered are distributed mainly in the reservoir of Jurassic(J1),Tertiary(R) and Quaternary (Q). Jurassic section is mainly composed of fluvial facies and offshore shallow lake deposition, interbedded with paludal sediment, the lithology is charac teristic of sandstone and mudstone, interbedded with coals. However, Cenozoic is composed of lucustrine and fluvial facies, and the lithology is characteristic of sandstone, mudstone, carbonate rock, interbedded with salt-rock, gypsum, with the palaeosalinity ranging 15‰~60‰.   Illite, illite-smectite, montmorillonite, chlorite, kaolinite and a small amoun t of chlorite-montmorillonite, palygorskite,holloysite are major clay mineralsin Qaidam basin. The clay mineral in sandstone is considered to be automorphic c rystal which is produced in diagenetic period. The monoblastic texture of illite , kaolinite and chlorite in mudstone is anhedral crystal, and its smooth, irregular outline reflected the terrigenous genesis of clay mineral.   The clay mineral contents vary with different depth and horizon. The kaolinite c ontent is 44.4% in J1 and 5.6% in E13-E23. The chlorite content va ry between 18.9%~12% in Cenozoic.However, it decreases to 9.9% in Jurassic. M ontmorillonite is concentrated in Quaternary and modern sediment. The con tent of illite-smectite in N1-N32 is 42.3% in highest, and

  7. Characteristics of Clay Minerals in the Northern South China Sea and Its Implications for Evolution of East Asian Monsoon since Miocene

    Institute of Scientific and Technical Information of China (English)

    Wan Shiming; Li Anchun; Xu Kehui; Yin Xueming

    2008-01-01

    Clay mineral assemblages, crystallinity, chemistry, and micromorphology of clay particles in sediments from ODP Site 1146 in the northern South China Sea (SCS) were analyzed, and used to trace sediment sources and obtain proxy records of the past changes in the East Asian monsoon climate since the Miocene, based on a multi-approach, including X-ray diffraction (XRD) and scanning electron microscopy combined with energy dispersive X-ray spectrometry (SEM-EDS). Clay minerals consist mainly of illite and smectite, with associated chlorite and kaolinite. The illite at ODP Site 1146 has very well-to-well crystallinity, and smectite has moderate-to-poor crystallinity. In SEM the smectite particles at ODP Site 1146 often appear cauliflower-like, a typical micromorphology of volcanic smecites. The smectite at ODP Site 1146 is relatively rich in Si element, but poor in Fe, very similar to the smectite from the West Philippine Sea. In contrast, the chemical composition of illite at ODP Site 1146 has no obvious differences from those of the Loess plateau, Yellow River, Yangtze River, and Pearl River. A further study on sediment source indicates that smectite originates mainly from Luzon, kaolinite from the Pearl River, and illite and chlorite from the Pearl River, Taiwan and/or the Yangtze River. The clay mineral assemblages at ODP Site 1146 were not only controlled by continental eathering regimes surrounding the SCS, but also by the changing strength of the transport processes. The ratios of (illite+chlorite)/smectite at ODP Site 1146 were adopted as proxies for the East Asian monsoon evolution. Relatively higher ratios reflect strongly intensified winter monsoon relative to summer monsoon, in contrast, lower ratios indicate a strengthened summer monsoon relative to winter monsoon. The consistent variation of this clay proxy from those of Loess plateau, eolian deposition in the North Pacific, planktonic, benthic foraminifera, and black carbon in the SCS since 20 Ma shows

  8. Clay minerals and Sr-Nd isotopes of the sediments along the western margin of India and their implication for sediment provenance

    Digital Repository Service at National Institute of Oceanography (India)

    Kessarkar, P.M.; Rao, V.P.; Ahmad, S.M.; Babu, G.A.

    For the convenience of description, the study region is divided into three geographic areas based on the variations in clay mineral distribu- tion and Sr^Nd isotopic composition of the sedi- ments. These are the Indus^Gulf of Kachchh re- gion, the Saurashtra... Institute, Hyderabad, for their encouragement and the use of their facilities. P.M.K. wishes to thank the CSIR, New Delhi, for providing a Senior Research Fellowship. We thank the referees (Dr. N. Fagel, an anonymous reviewer and Professor Chamley...

  9. Method of Identifying Clay Mineral by X-Ray Diffraction Analysis%用X射线衍射分析鉴定粘土矿物的方法

    Institute of Scientific and Technical Information of China (English)

    蒲海波

    2011-01-01

    Combined with the analysis executed by clay mineral in constructing material of dams of our institute , the principal of X-ray diffraction analysis, preparation of specimens and testing methods are introduced, and the graph of X-ray diffraction is interpreted and analyzed as well.%该文结合我院对筑坝材料中粘土矿物的分析,对X射线衍射分析的原理、样品制备及试验方法进行了介绍,对试验得到的衍射图谱进行了解译分析.

  10. Evaluation of first-row transition metal oxides supported on clay minerals for catalytic growth of carbon nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Tsoufis, Theodoros [Department of Materials Science and Engineering, University of Ioannina, GR-45110 Ioannina (Greece); Jankovic, Lubos [Department of Physics, University of Ioannina, GR-45110 Ioannina (Greece); Gournis, Dimitrios [Department of Materials Science and Engineering, University of Ioannina, GR-45110 Ioannina (Greece)], E-mail: dgourni@cc.uoi.gr; Trikalitis, Pantelis N. [Department of Chemistry, University of Crete, GR-71409 Heraklion (Greece); Bakas, Thomas [Department of Physics, University of Ioannina, GR-45110 Ioannina (Greece)], E-mail: tbakas@cc.uoi.gr

    2008-08-25

    In the present work we employed various transition metals (Cr, Mn, Fe, Co, Ni, Cu and Zn) loaded on different smectite clays (laponite and montmorillonite) as catalysts in synthesis of carbon nanostructures (mainly nanotubes) and we report the effect of the nature of the catalytic centers and type of aluminosilicate layers in the morphology, quality and structure on the final products. Owing to their unique swelling, ion-exchange and intercalation properties smectite clays were easily, uniformly and reproducibly loaded with metal cations. Different homoionic forms of montmorillonite and laponite were prepared containing first-row transition metals and the synthesis of carbon nanostructures was carried out at 700 deg. C using an acetylene/nitrogen mixture. A variety of analytical techniques (XRD, Raman, SEM, TEM and thermal analysis) were used to fully characterize the final materials. Iron-, cobalt-, nickel- and manganese-exchanged clays showed to be effective catalysts for the production of carbon nanotubes, while acetylene decomposition over copper-exchanged clays resulted to the creation of carbon spheres. The resulting hybrid systems are particularly attractive for polymer reinforcing applications since the combined action of clay-carbon nanotubes in polymer matrixes can provide outstanding properties to the resulting composite materials.

  11. Evolution of clay mineral assemblages in the Tinguiririca geothermal field, Andean Cordillera of central Chile: an XRD and HRTEM-AEM study

    Science.gov (United States)

    Vázquez, M.; Nieto, F.; Morata, D.; Droguett, B.; Carrillo-Rosua, F. J.; Morales, S.

    2014-08-01

    HRTEM textural evidence shows that clay minerals in the Tinguiririca geothermal field (Andean Cordillera, central Chile) are the result of direct alteration of former volcanic glass and minerals by hydrothermal fluids at similar temperatures to the present day. They show the classical pattern of diagenetic transformation from smectite at the top to illite at the bottom, with the progressive formation of corrensite and chlorite. The high fluid/rock ratio, disposability of necessary cations and absence of previous detrital phyllosilicates allow the consideration of this area as a natural laboratory to establish the extreme ideal conditions for very low-T reactions. Transformations from smectite to R1 illite-smectite (I-S) and from these to R3 mixed-layers occur respectively at 80-120 °C and 125-180 °C. In spite of ideal genetic conditions, the new-formed minerals show all the defective character and lack of textural and chemical equilibrium previously described in the literature for diagenetic and hydrothermal low-temperature assemblages. Chemistry of smectite-illite phases evolves basically through a diminution of the pyrophyllitic component toward a theoretical muscovite (Si4 + + □ -> Al3 ++ K+). However, a second chemical vector (Si4 ++ Mg2 + → Al3 ++ Al3 +), that is, decreasing of the tschermack component, also contributes to the evolution toward the less Si-more Al rich muscovite in relation to the original smectite. Residual Mg (and Fe) from the latter reaction is consumed in the genesis of chloritic phases. Nevertheless, as a consequence of the lack of chemical equilibrium (probably because of the short time-scale of the geothermal alteration processes), the composition of clay minerals is highly heterogeneous at the level of a single sample. Consequently, the respective fields of smectite, R1 I-S and R3 I-S overlap each other, making the distinction among these three phases impossible based exclusively on chemical data.

  12. Late-Quaternary variations in clay minerals along the SW continental margin of India: Evidence of climatic variations

    Digital Repository Service at National Institute of Oceanography (India)

    Chauhan, O; Sukhija, B.S.; Gujar, A.R.; Nagabhushanam, P.; Paropkari, A.L.

    Down-core variations in illite, chlorite, smectite and kaolinite (the major clays) in two sup(14)C-dated cores collected along the SW continental margin of India show that illite and chlorite have enhanced abundance during 20-17, 12.5, 11-9.5, and 5...

  13. Mineral catalysis of the formation of the phosphodiester bond in aqueous solution - The possible role of montmorillonite clays

    Science.gov (United States)

    Ferris, James P.; Ertem, Gozen; KAMALUDDIN; Agarwal, Vipin; Hua, Lu Lin

    1989-01-01

    The possible role of montmorillonite clays in the spontaneous formation on the primitive earth of the phosphodiester bond in the presence of water was investigated in experiments measuring the binding of various nucleosides and nucleotides with Na(+)-montmorillonite 22A and the reactions of these compounds with a water-soluble carbodiimide. It was found that, at neutral pH, adenine derivatives bind stronger than the corresponding uracil derivatives, consistent with the protonation of the adenine by the acidic clay surface and a cationic binding of the protonated ring to the anionic clay surface. The reaction of the 5-prime-AMP with carbodiimide resulted in the formation of 2-prime,5-prime-pApA (18.9 percent), 3-prime,5-prime-pApA (11 percent), and AppA (4.8 percent). The yields of these oligomers obtained when poly(U) was used in place of the clay were 15.5 percent, 3.7 percent, and 14.9 percent AppA, respectively.

  14. Zeolite and clay-mineral induced resistivity in simulated reservoir. [Artificial cores prepared by mixing and compacting clinoptilolite, smectite and illite, with medium-grained quartz sand

    Energy Technology Data Exchange (ETDEWEB)

    Reynolds, W.R.; Williford, C.W. (Mississippi Univ., University, MS (USA))

    1991-02-01

    Clay-minerals dispersed in reservoir sands affect electric log response and register reduced resistivity values. Natural zeolites however, with large microporosities and water content could have a greater affect on resistivity measurements. Resistivity values were measured on a series of artificial cores prepared by mixing and compacting various percentages each of clinoptilolite, smectite and illite, with a medium-grained, moderately sorted quartz sand. Various concentrations of NaCl solution mixed with 39 API crude oil were circulated through each core. Impedance measurements were taken, resistance values segregated, and resistivities determined for each core. Water saturation values were calculated from the empirical resistivity values and porosities using a modified Simandoux equation. These values appeared to be much higher for those cores which contained the zeolite clinoptilolite. Clinoptilolite, when dispersed in a simulated reservoir sand and treated as a dispersed smectite or illite, produced inflated saturation values. This inflation effect is thought to be due to the more extensive microporosity and larger micropore water content of the zeolite. Therefore, from the empirical aspect, resistivity measurements of reservoir sands containing a dispersed zeolite, rather than a clay-mineral, would probably yield misleading water saturation values. 3 figs., 26 refs., 3 tabs.

  15. Structure, dynamics, and function of the hammerhead ribozyme in bulk water and at a clay mineral surface from replica exchange molecular dynamics.

    Science.gov (United States)

    Swadling, Jacob B; Wright, David W; Suter, James L; Coveney, Peter V

    2015-03-01

    Compared with proteins, the relationship between structure, dynamics, and function of RNA enzymes (known as ribozymes) is far less well understood, despite the fact that ribozymes are found in many organisms and are often conceived as "molecular fossils" of the first self-replicating molecules to have arisen on Earth. To investigate how ribozymal function is governed by structure and dynamics, we study the full hammerhead ribozyme in bulk water and in an aqueous clay mineral environment by computer simulation using replica-exchange molecular dynamics. Through extensive sampling of the major conformational states of the hammerhead ribozyme, we are able to show that the hammerhead manifests a free-energy landscape reminiscent of that which is well known in proteins, exhibiting a "funnel" topology that guides the ribozyme into its globally most stable conformation. The active-site geometry is found to be closely correlated to the tertiary structure of the ribozyme, thereby reconciling conflicts between previously proposed mechanisms for the self-scission of the hammerhead. The conformational analysis also accounts for the differences reported experimentally in the catalytic activity of the hammerhead ribozyme, which is reduced when interacting with clay minerals as compared with bulk water.

  16. The Study of Clay Minerals Distribution in Lianhua Reservoir%莲花油层中粘土矿物分布规律研究

    Institute of Scientific and Technical Information of China (English)

    唐洪明; 曾凡刚; 陈忠; 赵敬松; 沈明道; 唐清山; 柴利文; 魏桂萍

    2001-01-01

    The Lianhua reservoir of Shahejie group(geology period E1) in Gaosheng Oil field , located in Liaohe granen faulting basin, is rich in heavy crude oil, with the burial depth being 1 450~1 700 m.The reservoirs have been under development for 22 years. The company has made great profit from the reservoir development by means of steam-flooding technology, but some problems have been found in the reservo i r with the technology application, because the difficulty in reservoir developme nt is increasing with the frequency of applying the technology. By the end of 19 98 the average steam flooding for every well has been four times, but the more s team-flooding, the less satisfactory the efforts to increase the production.   Therefore, a more comprehensive study of the types, content, and the horizonta l and vertical distribution characteristics of the clay minerals in the reservoi r is of most important consequence to the design of the heavy crude oil developme nt, reservoir protection, reservoir evaluation, and enhanced oil recovery (EOR) etc. The clay minerals in Lianhua reservoir are systematically studied by means of X-ray diffraction, scan electronic microscope and heat simulation experiment s.   The Lianhua reservoir is a sediment by gravity flow, with the rock types bein g gravel, sandstone, and mudstone, and the sedimentary depth being 50~600 m. L ian hua reservoir has excellent physical property, with the porosity being 20%~26% and the permeability being 1~4 μm2.   The studies show that the major clay minerals in Lianhua reservoir are montmoril lonite(60%~85%), illite (8%~20%), kaolinite (5%~25%), and chlorite (<5%). T he montm orillonite content decreases with the increase of the burial depth, but the kaol inite and illite content are just the opposite, because the porosity fluid in sa ndstone and gravels more easily circulative than that in mudstone, and the mont morillonite in sandstone can more easily convert into other

  17. Metal oxides, clay minerals and charcoal determine the composition of microbial communities in matured artificial soils and their response to phenanthrene.

    Science.gov (United States)

    Babin, Doreen; Ding, Guo-Chun; Pronk, Geertje Johanna; Heister, Katja; Kögel-Knabner, Ingrid; Smalla, Kornelia

    2013-10-01

    Microbial communities in soil reside in a highly heterogeneous habitat where diverse mineral surfaces, complex organic matter and microorganisms interact with each other. This study aimed to elucidate the long-term effect of the soil mineral composition and charcoal on the microbial community composition established in matured artificial soils and their response to phenanthrene. One year after adding sterile manure to different artificial soils and inoculating microorganisms from a Cambisol, the matured soils were spiked with phenanthrene or not and incubated for another 70 days. 16S rRNA gene and internal transcribed spacer fragments amplified from total community DNA were analyzed by denaturing gradient gel electrophoresis. Metal oxides and clay minerals and to a lesser extent charcoal influenced the microbial community composition. Changes in the bacterial community composition in response to phenanthrene differed depending on the mineral composition and presence of charcoal, while no shifts in the fungal community composition were observed. The abundance of ring-hydroxylating dioxygenase genes was increased in phenanthrene-spiked soils except for charcoal-containing soils. Here we show that the formation of biogeochemical interfaces in soil is an ongoing process and that different properties present in artificial soils influenced the bacterial response to the phenanthrene spike.

  18. Applied mineralogy of the constituent clays of the mineral wastes from the coal mines in the Teruel mining zone; Mineralogia aplicada de arcillas constitutivas de esteriles en minas de carbon de la zona minera de Teruel

    Energy Technology Data Exchange (ETDEWEB)

    Bastida, J.; Lopez Buendia, A.M.; Serrano, J.; De La Torre, J.; Sienes, M. [Univ. Valencia, Valencia (Spain). Dept. de Geologia

    1993-12-31

    The coals of the district of Teruel (NE Spain) presents as mine wastes several industrial minerals and rocks (sands, kaolins, clays, Al-sulfates,...) the mining of which would be interesting. The aim of this work is the mineralogical and ceramic characterisation of these clays. So mineralogical and petrographical data as well as technological data concerning granulometry, chemical analysis and Atteberg index have been used in order to compare these clays with those analysed and typified in previous works and with those actually used as ceramic raw materials in the NE of Teruel. 26 refs., 5 figs., 4 tabs.

  19. Comment on "Evaluation of X-ray diffraction methods for determining the crystal growth mechanisms of clay minerals in mudstones, shales and slates," by L. N. Warr and D. R. Peacor

    Science.gov (United States)

    Eberl, D.D.; Srodon, J.; Drits, V.A.

    2003-01-01

    A recent paper by Warr and Peacor (2002) suggested that our use of the Bertaut-Warren-Averbach technique (MudMaster computer program) for studying changes in crystallite thickness distributions (CTDs) of clay minerals during diagenesis and very low-grade metamorphism is not reliable because it is dependent on many variables which can not be fully controlled. Furthermore, the authors implied that the measured shapes of CTDs cannot be used with confidence to deduce crystal growth mechanisms and histories for clays, based on our CTD simulation approach (using the Galoper computer program). We disagree with both points, and show that the techniques are powerful, reliable and useful for studying clay mineral alteration in rocks. ?? 2003 Schweiz. Mineral. Petrogr. Ges.

  20. Chemical and mineralogical characteristics of French green clays used for healing

    Science.gov (United States)

    Williams, L.B.; Haydel, S.E.; Giese, R.F.; Eberl, D.D.

    2008-01-01

    The worldwide emergence of infectious diseases, together with the increasing incidence of antibiotic-resistant bacteria, elevate the need to properly detect, prevent, and effectively treat these infections. The overuse and misuse of common antibiotics in recent decades stimulates the need to identify new inhibitory agents. Therefore, natural products like clays, that display antibacterial properties, are of particular interest. The absorptive properties of clay minerals are well documented for healing skin and gastrointestinal ailments. However, the antibacterial properties of clays have received less scientific attention. French green clays have recently been shown to heal Buruli ulcer, a necrotic or 'flesh-eating' infection caused by Mycobacterium ulcerans. Assessing the antibacterial properties of these clays could provide an inexpensive treatment for Buruli ulcer and other skin infections. Antimicrobial testing of the two clays on a broad-spectrum of bacterial pathogens showed that one clay promotes bacterial growth (possibly provoking a response from the natural immune system), while another kills bacteria or significantly inhibits bacterial growth. This paper compares the mineralogy and chemical composition of the two French green clays used in the treatment of Buruli ulcer. Mineralogically, the two clays are dominated by 1Md illite and Fe-smectite. Comparing the chemistry of the clay minerals and exchangeable ions, we conclude that the chemistry of the clay, and the surface properties that affect pH and oxidation state, control the chemistry of the water used to moisten the clay poultices and contribute the critical antibacterial agent(s) that ultimately debilitate the bacteria. Copyright ?? 2008, The Clay Minerals Society.

  1. Dioxin congener patterns in commercial catfish from the United States and the indication of mineral clays as the potential source.

    Science.gov (United States)

    Huwe, J K; Archer, J C

    2013-01-01

    Since 1991 the US Department of Agriculture (USDA) has conducted annual surveys of pesticide residues in foods under the Agricultural Marketing Service's Pesticide Data Program (PDP). To assess chemical residues in domestically marketed catfish products, 1479 catfish samples were collected during the 2008-2010 PDPs. A subset of 202 samples was analysed for 17 toxic polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs). The average pattern of the individual PCDD/F congener concentrations in the catfish was rather unique in that it had almost no measurable amounts of polychlorinated dibenzofurans (PCDFs), but all PCDDs were present. This pattern was more dominant in the domestically produced catfish products than in the imported products (China/Taiwan). Comparison of the pattern to known sources of PCDD/Fs showed strong similarities to the pattern of PCDD/Fs found in kaolin clays which have often been used as anti-caking agents in animal feeds. To investigate whether catfish feeds may be the source of the PCDD/Fs found in the catfish, archived catfish feed data from a US Food and Drug Administration (USFDA) database were examined. In 61 out of 112 feed samples, the PCDD concentrations were 50 times higher than the PCDF concentrations and resembled the pattern found in the catfish products and in clays mined in the south-eastern United States. Although the source of PCDD/Fs in domestically marketed catfish products cannot be definitively established, mined clay products used in feeds should be considered a likely source and, given the wide concentration range of PCDD/Fs that has been found in clays, a critical control point for PCDD/Fs entrance to the food supply.

  2. Europium retention onto clay minerals from 25 to 150 °C: Experimental measurements, spectroscopic features and sorption modelling

    Science.gov (United States)

    Tertre, E.; Berger, G.; Simoni, E.; Castet, S.; Giffaut, E.; Loubet, M.; Catalette, H.

    2006-09-01

    The sorption of Eu(III) onto kaolinite and montmorillonite was investigated up to 150 °C. The clays were purified samples, saturated with Na in the case of montmorillonite. Batch experiments were conducted at 25, 40, 80 and 150 °C in 0.5 M NaClO 4 solutions to measure the distribution coefficients (Kd) of Eu as a trace element (argiles: influence des silicates. Ph.D. Thesis, Université Paris Sud, France, 330p].

  3. Detection of Soluble and Fixed NH4+ in Clay Minerals by DTA and IR Reflectance Spectroscopy : A Potential Tool for Planetary Surface Exploration

    Science.gov (United States)

    Janice, Bishop; Banin, A.; Mancinelli, R. L.; Klovstad, M. R.; DeVincenzi, Donald L. (Technical Monitor)

    2001-01-01

    Nitrogen is an essential element for life. It is the only element among the six major biogenic elements, C, O, S, O, P, H, whose presence in the Martian soil has not been positively and directly established. We describe here a study assessing the ability to detect NH4 in soils by two methods: differential thermal analysis (DTA) and infrared (IR) reflectance spectroscopy. Four standard clay minerals (kaolinite, montmorillonite, illite and attapulgite) and an altered tephra sample from Mauna Kea were treated with NH4 in this study. Samples of the NH4-treated and leached clays were analyzed by DTA and infrared (IR) reflectance spectroscopy to quantify the delectability of soluble and sorbed/fixed NH4. An exotherm at 270-280 C was clearly detected in the DTA curves of NH4-treated (non-leached) samples. This feature is assigned to the thermal decomposition reaction of NH4. Spectral bands observed at 1.56, 2.05, 2.12, 3.06, 3.3, 3.5, 5.7 and 7.0 microns in the reflectance spectra of NH4-treated and leached samples are assigned to the sorbed/fixed ammonium in the clays. The montmorillonite has shown the most intense absorbance due to fixed ammonium among the leached samples in this study, as a result of its high cation sorption capacity. It is concluded that the presence of sorbed or fixed NH4 in clays may be detected by infrared (IR) reflectance or emission spectroscopy. Distinction between soluble and sorbed NH4 may be achieved through the presence or absence of several spectral features assigned to the sorbed NH4 moietyi and, specifically, by use of the 4.2 micrometer feature assigned to solution NH4. Thermal analyses furnish supporting evidence of ammonia in our study through detection of N released at temperatures of 270-330 C. Based on these results it is estimated that IR spectra measured from a rover should be able to detect ammonia if present above 20 mg NH4/g sample in the surface layers. Orbital IR spectra and thermal analyses measured on a rover may be able to

  4. 粘土矿物在气候环境变化研究中的应用进展%Application Progress of Clay Minerals in the Researches of Climate and Environment

    Institute of Scientific and Technical Information of China (English)

    孙庆峰; 陈发虎; Christophe Colin; 张家武

    2011-01-01

    在古环境和古气候的重建中,粘土矿物和碳-氧同位素、孢粉、树轮、冰芯等代用指标一样具有同等重要的地位.在没有地质构造运动影响时,气候是影响粘土矿物形成的主要因素,沉积物中的粘土矿物可用来分析古气候和古环境.粘土矿物及其组合可以独立或作为主要指标反映气候和环境变化,并已应用于高分辨率的晚第四纪地层的气候环境研究中.粘土矿物在很短的时间内也会发生明显地变化,不仅可以反映千年-百年尺度的气候环境变化,而且也可以反映几十年尺度的古气候环境变化过程.粘土矿物与其它指标对同一气候环境响应的相位差有待深入研究.不同的半定量分析方法测量出的同一剖面中粘土矿物的含量变化趋势和特征具有一致性.%In constructing paleoenvironment and paleoclimate clay minerals could be used same as the proxies of carben-oxygen isotope, pollen, tree ring, ice core to decipher the information of climate and environment. In the geological time without tectonic movement climate is the primary factor to dominate clay mineral formation and clay mineral could be utilized to analyze paleoclimate and paleoenvironment. Clay minerals and their assemblages can be independent or primary good proxies of climatic and environmental changes. Clay minerals have been used in high solution strata of the late Quaternary. Clay minerals can change obviously in a short time and record the climatic and environmental changing history of thousand-hundred years or even several decades. The climatic and environmental lag recorded by clay minerals and other proxies needs to be studied thoroughly. Clay mineral quantity tendencies and characteristics in a section measured by different semi-quantity methods are uniform.

  5. Distribution of clay minerals in marine sediments off Chennai, Bay of Bengal, India: Indicators of sediment sources and transport processes .

    Digital Repository Service at National Institute of Oceanography (India)

    Veerasingam, S.; Venkatachalapathy, R.; Ramkumar, T.

    -ray diffraction analysis was performed on powdered sediment samples using a Seifert (JSO-DEBYEFLEX 2002) X-ray diffractometer having a curved graphite crystal diffracted monochromator, with a source of CuK� radiation and a NaI (TI) scintillation counter detector.... The maximum value of crystallinity indicates the minerals are in ordered form and the minimum value is taken as disordered form. Therefore, it is important to find the crystallinity of quartz rather than the other associated minerals. Crystallinity index...

  6. Atypical subtrochanteric and diaphyseal femoral fractures: report of a task force of the American Society for Bone and Mineral Research

    DEFF Research Database (Denmark)

    Shane, Elizabeth; Burr, David; Ebeling, Peter R;

    2010-01-01

    Reports linking long-term use of bisphosphonates (BPs) with atypical fractures of the femur led the leadership of the American Society for Bone and Mineral Research (ASBMR) to appoint a task force to address key questions related to this problem. A multidisciplinary expert group reviewed pertinent....... Physicians and patients should be made aware of the possibility of atypical femoral fractures and of the potential for bilaterality through a change in labeling of BPs. Research directions should include development of animal models, increased surveillance, and additional epidemiologic and clinical data...

  7. Mycotoxins modify the barrier function of Caco-2 cells through differential gene expression of specific claudin isoforms: Protective effect of illite mineral clay.

    Science.gov (United States)

    Romero, Alejandro; Ares, Irma; Ramos, Eva; Castellano, Víctor; Martínez, Marta; Martínez-Larrañaga, María-Rosa; Anadón, Arturo; Martínez, María-Aránzazu

    2016-04-15

    Aflatoxin B1 (AFB1), fumonisin B1 (FB1), ochratoxin A (OTA) and T-2 toxin (T2) are mycotoxins that commonly contaminate the food chain and cause various toxicological effects. Their global occurrence is regarded as an important risk factor for human and animal health. In this study, the results demonstrate that, in human Caco-2 cells, AFB1, FB1, OTA and T2 origin cytotoxic effects, determining cell viability through MTT assay and LDH leakage, and decrease trans-epithelial electrical resistance (TEER). The decrease in barrier properties is concomitant with a reduction in the expression levels of the tight junction constituents claudin-3, claudin-4 and occludin. The protective effect of mineral clays (diosmectite, montmorillonite and illite) on alterations in cell viability and epithelial barrier function induced by the mycotoxins was also evaluated. Illite was the best clay to prevent the mycotoxin effects. Illite plus mycotoxin co-treatment completely abolished AFB1 and FB1-induced cytotoxicity. Also, the decreases in the gene expression of claudins and the reduction of TEER induced by mycotoxins were reversed by the illite plus mycotoxin co-treatment. In conclusion, these results demonstrated that mycotoxins AFB1, FB1, T2 and OTA disrupt the intestinal barrier permeability by a mechanism involving reduction of claudin isoform expressions, and illite counteracts this disruption.

  8. Langmuir-Blodgett monolayers of cationic dyes in the presence and absence of clay mineral layers: N,N'-dioctadecyl thiacyanine, octadecyl rhodamine B and laponite.

    Science.gov (United States)

    Hussain, Syed Arshad; Schoonheydt, Robert A

    2010-07-20

    Langmuir-Blodgett (LB) films of N,N'-dioctadecyl thiacyanine perchlorate (TC18) and octadecyl rhodamine B chloride (RhB18) and their mixtures in the presence and absence of clay mineral layers were investigated by recording surface pressure-area (pi-A) isotherms and by UV-vis and fluorescence spectroscopies. The pi-A isotherms of TC18, RhB18, and their mixtures are characteristic of liquid expanded state behavior with repulsive interactions between the two cationic dyes. In the presence of laponite, the pi-A isotherms show liquid expanded and condensed-state behavior. In laponite dispersions and in monolayers, TC18 has a strong tendency to aggregate with formation of H- and J- aggregates. The absorption and fluorescence maxima of the monomers in the films are at 435 nm and at 480 nm; H-dimers have an absorption maximum around 410 nm and do not fluoresce. J-dimers are present in all the films with absorption maximum at 461 nm and fluorescence at 463 nm. RhB18 is mainly present as monomers in the LB films with an absorption maximum at 576 nm and fluorescence at 595 nm. Fluorescence resonance energy transfer from TC18 to RhB18 has been observed in clay dispersions and in films with and without laponite. The optimum condition for TC18 --> RhB18 fluorescence energy transfer in the films is 90 mol % TC18 + 10 mol % RhB18.

  9. Late Quaternary clay minerals off Middle Vietnam in the western South China Sea: Implications for source analysis and East Asian monsoon evolution

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    High-resolution clay mineral records combined with oxygen isotopic stratigraphy over the past 450 ka during late Quaternary from Core MD05-2901 off Middle Vietnam in the western South China Sea are reported to reconstruct a history of East Asian monsoon evolution.Variations in Illite,chlorite,and kaolinite contents indicate a strong glacial-interglacial cyclicity,while changes in smectite content present a higher frequency cyclicity.The provenance analysis indicates a mixture of individual clay minerals from various sources surrounding the South China Sea.Smectite derived mainly from the Sunda shelf and its major source area of the Indonesian islands.Illite and chlorite originated mainly from the Mekong and Red rivers.Kaolinite was provided mainly by the Pearl River.Spectral analysis of the kaolinite/(illite+chlorite) ratio displays a strong eccentricity period of 100 ka,implying the ice sheet-forced winter monsoon evolution; whereas higher frequency changes in the smectite content show an ice sheet-forced obliquity period of 41 ka,and precession periods of 23 and 19 ka and a semi-precession period of 13 ka as well,implying the tropical-forced summer monsoon evolution.The winter monsoon evolution is generally in coherence with the glacial-interglacial cyclicity,with intensified winter monsoon winds during glacials and weakened winter monsoon winds during interglacials; whereas the summer monsoon evolution provides an almost linear response to the summer insolation of low latitude in the Northern Hemisphere,with strengthened summer monsoon during higher insolation and weakened summer monsoon during lower insolation.The result suggests that the high-latitude ice sheet and low-latitude tropical factor could drive the late Quaternary evolution of East Asian winter and summer monsoons,respectively,implying their diplex and self-contained forcing mechanism.

  10. Comparison of the sorption behaviors and mechanisms of perfluorosulfonates and perfluorocarboxylic acids on three kinds of clay minerals.

    Science.gov (United States)

    Zhao, Lixia; Bian, Jingna; Zhang, Yahui; Zhu, Lingyan; Liu, Zhengtao

    2014-11-01

    The sorption of four perfluoroalkyl acids (PFAAs) [perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS), perfluorooctanoic acid (PFOA) and perfluorohexanoic acid (PFHxA)] on three typical minerals [montmorillonite (MM), kaolinite (KL) and hematite (HM)] was studied. The sorption of PFOS and PFHxS was much stronger than PFOA and PFHxA. The sorption of each PFAA on the minerals followed an order of HM>KL>MM, even though MM was positively while KL and HM were negatively charged, implying that the sorption is driven by some other interactions besides electrostatic attraction. The sorption decreased with an increase in pH and a decrease in ionic strength of the solution, and their impacts on PFOS were much stronger than other three PFAAs. Surface complexing and hydrogen-bonding could make great contributions to the sorption of PFOS on the minerals. The results are important for understanding the transport and fate of PFAAs in sediment and ground water.

  11. 金厂沟梁地区土壤含水粘土矿物含量短波红外光谱反演%Inversion of Hydrated Clay Mineral Content in Soil of Jinchanggouliang Area Based on SWIR

    Institute of Scientific and Technical Information of China (English)

    曹会; 邢立新; 潘军; 刘立文; 杨东旭; 王莹

    2013-01-01

    Based on the physical mechanism that clay mineral can produce characteristic spectrum at shortwave infrared ray ( SWIR) , we chose the characteristic wave band of clay mineral, used the actual analysis results and test data of the mineral components, and adopted multivariate linear regression analysis to build model for inversing the soil clay mineral content of Jinchanggouliang area of Inner Mongolia. The study results demonstrated that applying soil spectral reflectance which was corresponding with the characteristic wave band to establish forecast model could carry out the inversion of hydrated clay mineral content in the soil of this area. The clay mineral content influenced the discretion of the soil spectral reflectance.%基于粘土矿物在短波红外线处产生特征光谱的机理,选出其特征波段,利用矿物组分的实际分析结果和测试数据,采用多元线性回归方法建立模型,对内蒙古金厂沟梁地区的土壤粘土矿物含量进行了反演.研究结果表明:应用特征波段对应的土壤光谱反射率建立预测模型可以用于该地区土壤粘土矿物含量的反演;粘土矿物含量的多少影响光谱反射率的高低.

  12. Experimental Study on Gold Ore with Clay-bearing Mineral%含泥质矿物的金矿石浮选试验研究

    Institute of Scientific and Technical Information of China (English)

    高起鹏

    2014-01-01

    对某金矿石进行的浮选试验研究结果表明,含金黄铁矿中泥质矿物是影响金选矿工艺指标的主要因素,在强化载金黄铁矿浮选的同时,选择合理的调整剂可以显著的提高金的选矿工艺指标。经过试验研究,在原矿含金品位为2.53 g/t时,浮选获得了金精矿含金品位为62.50g/t ,金回收率为92.60%的工艺指标。新型复合捕收剂sk和调整剂羧甲基纤维素的应用是提高精矿含金品位的关键。%An experimental study result of a kind of gold ore shows that the main factor affecting the miner-al flotation process index is the clay mineral in gold-bearing pyrite . At the same time of strengthening flo-tation of gold loaded pyrite , choosing a reasonable adjustment can significantly increase the mineral flota-tion process index . Through experimental study , when the gold grade of a raw ore is 2 .53 g/t ,the better process indexes have gain by flotation :the grade of gold-bearing gold concentrates is 62 .50 g/t , and the gold recovery is 92 .60% .The application of new type composite collectors sk and regulator carboxymeth-ylcellulose is the key to increase the gold concentrate grade .

  13. Infrared spectroscopic studies of the effect of elevated temperature on the association of pyroglutamic acid with clay and other minerals

    Science.gov (United States)

    Macklin, J. W.; White, D. H.

    1985-01-01

    Fourier transform i.r. measurements of L-pyroglutamic acid dispersed in a matrix of a clay, silica or alumina have been obtained at various temperatures between 25 and 220 degrees C. The i.r. spectrum of L-pyroglutamic acid varies in a manner dependent upon the matrix material and shows considerable change as the temperature of the mixtures is increased. The differences in the spectrum at elevated temperatures are explained in terms of a chemical reaction between hydroxyl groups in the matrix and the carboxylic acid. The i.r. spectra of trimethylsilyl derivatives of L-pyroglutamic acid and aluminum pyroglutamate were also measured to assist the understanding of spectra and interpretation of the spectral changes dependent upon increasing temperature.

  14. Visible–Near-Infrared Spectroscopy Can Predict the Clay/Organic Carbon and Mineral Fines/Organic Carbon Ratios

    DEFF Research Database (Denmark)

    Hermansen, Cecilie; Knadel, Maria; Møldrup, Per;

    2016-01-01

    The ratios of mineral fines (... of preferential flow, water repellency, and chemical adsorption. Conventional texture and OC measurements are time consuming and expensive, and visible–near-infrared (vis-NIR) spectroscopy may provide a fast and inexpensive alternative for obtaining the n- and m-ratios. In this study, a total of 480 soil samples...

  15. Modelling of the physico-chemical behaviour of clay minerals with a thermo-kinetic model taking into account particles morphology in compacted material.

    Science.gov (United States)

    Sali, D.; Fritz, B.; Clément, C.; Michau, N.

    2003-04-01

    Modelling of fluid-mineral interactions is largely used in Earth Sciences studies to better understand the involved physicochemical processes and their long-term effect on the materials behaviour. Numerical models simplify the processes but try to preserve their main characteristics. Therefore the modelling results strongly depend on the data quality describing initial physicochemical conditions for rock materials, fluids and gases, and on the realistic way of processes representations. The current geo-chemical models do not well take into account rock porosity and permeability and the particle morphology of clay minerals. In compacted materials like those considered as barriers in waste repositories, low permeability rocks like mudstones or compacted powders will be used : they contain mainly fine particles and the geochemical models used for predicting their interactions with fluids tend to misjudge their surface areas, which are fundamental parameters in kinetic modelling. The purpose of this study was to improve how to take into account the particles morphology in the thermo-kinetic code KINDIS and the reactive transport code KIRMAT. A new function was integrated in these codes, considering the reaction surface area as a volume depending parameter and the calculated evolution of the mass balance in the system was coupled with the evolution of reactive surface areas. We made application exercises for numerical validation of these new versions of the codes and the results were compared with those of the pre-existing thermo-kinetic code KINDIS. Several points are highlighted. Taking into account reactive surface area evolution during simulation modifies the predicted mass transfers related to fluid-minerals interactions. Different secondary mineral phases are also observed during modelling. The evolution of the reactive surface parameter helps to solve the competition effects between different phases present in the system which are all able to fix the chemical

  16. The role of climate and vegetation in weathering and clay mineral formation in late Quaternary soils of the Swiss and Italian Alps

    Science.gov (United States)

    Egli, Markus; Mirabella, Aldo; Sartori, Giacomo

    2008-12-01

    Interactions between climate and soil remain ambiguous, particularly when silicate weathering and clay mineral formation and transformation rates are considered in relation to global climate changes. Recent studies suggest that climate affects weathering rates much less than previously thought. Here we show that the climate in the central European Alps has a significant, but indirect, influence on the weathering of soils through vegetation. The pattern of element leaching and mineral transformations is not only due to precipitation and temperature. Element leaching was greatest in subalpine forests near the timberline; weathering is lessened at higher and lower altitudes. Vegetation, therefore, contributes significantly to weathering processes. The highest accumulation of organic matter was found in climatically cooler sites (subalpine range) where the production of organic ligands, which enhance weathering, is greatest. Patterns of smectite formation and distribution had strong similarities to that of the elemental losses of Fe and Al ( R = 0.69; P climate, element leaching (Fe, Al, Ca, Mg, K, Na), and smectite formation is strongly nonlinear and driven by the podzolisation process, which is more pronounced near the timberline because of the bioclimatic constellation. Climate warming will probably, in the future, lead to a decrease in SOM stocks in the subalpine to alpine range because of more favourable conditions for biodegradation that would also affect weathering processes.

  17. Clay Play

    Science.gov (United States)

    Rogers, Liz; Steffan, Dana

    2009-01-01

    This article describes how to use clay as a potential material for young children to explore. As teachers, the authors find that their dialogue about the potential of clay as a learning medium raises many questions: (1) What makes clay so enticing? (2) Why are teachers noticing different play and conversation around the clay table as compared to…

  18. Geotechnical properties of Karwar marine clay

    Digital Repository Service at National Institute of Oceanography (India)

    Bhat, S.T.; Nayak, B.U.; Naik, R.L.

    Karwar marine clay possesses high plasticity characteristics with natural water content higher than the liquid limit. Liquidity index was as high as 1.7. Predominant clay mineral was kaolinite. Undrained shear strength showed an increasing trend...

  19. Amplification of plasmid DNA bound on soil colloidal particles and clay minerals by the polymerase chain reaction

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Polymerase chain reaction (PCR) was used to amplify a 600-base pair (bp) sequence of plasmid pGEX-2T DNA bound on soil colloidal particles from Brown soil (Alfisol) and Red soil (Ultisol), and three different minerals (goethite, kaolinite, montmorillonite). DNA bound on soil colloids, kaolinite, and montmorillonite was not amplified when the complexes were used directly but amplification occurred when the soil colloid or kaolinite-DNA complex was diluted, 10- and 20-fold. The montmorillonite-DNA complex required at least 100-fold dilution before amplification could be detected. DNA bound on goethite was amplified irrespective of whether the complex was used directly, or diluted 10- and 20-fold. The amplification of mineral-bound plasmid DNA by PCR is, therefore, markedly influenced by the type and concentration of minerals used. This information is of fundamental importance to soil molecular microbial ecology with particular reference to monitoring the fate of genetically engineered microorganisms and their recombinant DNA in soil environments.

  20. Ball clay

    Science.gov (United States)

    Virta, R.L.

    2011-01-01

    The article discusses the latest developments in the global ball clay mining industry, particularly in the U.S., as of June 2011. It cites several firms that are involved in ball clay mining in the U.S., including HC Spins Clay Co. Inc., the Imerys Group and Old Hickory Clay Co. Among the products made from ball clay are ceramic tiles, sanitaryware, as well as fillers, extenders and binders.

  1. Ab-Initio Modelling Of Surface Site Reactivity And Fluid Transport In Clay Minerals Case Study: Pyrophyllite

    Energy Technology Data Exchange (ETDEWEB)

    Churakov, S.V

    2005-03-01

    Pyrophyllite, Al{sub 2}[Si{sub 4}O{sub 10}](OH){sub 2}, is the simplest structural prototype for 2:1 dioctahedral phyllosilicate. Because the net electric charge in pyrophyllite is zero, it is the best candidate for investigating the non electrostatic contribution to sorption and transport phenomena in clays. Using ab-initio simulations, we have investigated the reactivity and structure of the water-solid interface on the basal plane and edge sites of pyrophyllite. The calculations predict slightly hydrophobic behaviour of the basal plane. For the high water coverage (100), (110) and (-110), lateral facets have a lower energy than for the (010), (130) and (-130) surfaces. Analysis of the surface reactivity reveals that the =Al-OH groups are most easily protonated on the (010), (130) and (-130) facets. The =Al-O-Si= sites will be protonated on the (100), (130), (110), (-110) and (-130) surfaces. The =Al-OH{sub 2} complexes are more easily de-protonated than the =Si-OH and =Al-OH sites. A spontaneous, reversible exchange of the protons between the solution and the edge sites has been observed in ab-initio molecular dynamics simulations at 300 K. Such near-surface proton diffusion may result in a significant contribution to the diffusion coefficients measured in neutron scattering experiments. (author)

  2. Microtektites and Associated Minerals in the Iridium-Rich Layer of Marine Clay From the Central North Pacific Ocean

    Science.gov (United States)

    Leung, I. S.

    2014-12-01

    Our study is based on a sample derived from a deep sea core (GPC3) from the mid-Pacific Ocean floor north of the Hawaiian Islands, provided by Jim Broda, Woods Hole Oceanographic Institution. The 65 Ma K/T boundary layer was identified by measurements of magnetic susceptibility (Doh, 1987) and Ir anomaly (Kyte et al., 1995) which peaked at a down-hole depth of 2055-2056 cm. Our sample of red clay was about 5 cubic cm in size. After wet-sieving for the size fraction greater than 38 microns, we hand-picked grains of interest under a binocular microscope. We found 40 microtektites (glass spherules, mostly devitrified), 12 olive-green aggregates composed of talc/magnetite, and 3 green and blue crystals of silicon carbide (SiC). There are many quartz grains having decorated deformation lamellae or mosaic structures. The olive-green talc/magnetite particles have textures and composition similar to materials found in chondritic meteorites, whereas, SiC crystals are known to occur in carbonaceous chondrites. These particles seem to implicate an affinity to meteorites. Ir-rich deposits world-wide are believed to have settled from dust produced by the Chicxulub Impact, but what object from space created the impact crater is rather uncertain. Our results reported here cannot rule out the possiblilty of impact by comets, because the nature of cometary dust particles are not very well known.

  3. Early diagenesis and clay mineral adsorption as driving factors of metal pollution in sediments: the case of Aveiro Lagoon (Portugal).

    Science.gov (United States)

    Martins, Maria Virgínia Alves; Mane, Miguel Ângelo; Frontalini, Fabrizio; Santos, José Francisco; da Silva, Frederico Sobrinho; Terroso, Denise; Miranda, Paulo; Figueira, Rubens; Laut, Lazaro Luiz Mattos; Bernardes, Cristina; Filho, João Graciano Mendonça; Coccioni, Rodolfo; Dias, João M Alveirinho; Rocha, Fernando

    2015-07-01

    This work aims to define the factors driving the accumulation of metals in the sediment of the lagoon of Aveiro (Portugal). The role of initial diagenetic processes in controlling trace metal retention in surface sediment is traced by mineralogy, magnetic susceptibility and geochemical analyses. Although several studies have focused on the metal distribution in this polihaline and anthropized coastal lagoon, most of them have been solely focused on the total metal concentrations. This study instead represents the first attempt to evaluate in a vast area of the Aveiro Lagoon the role of biogeochemical processes in metal availability and distribution in three extracted phases: exchangeable cations adsorbed by clay and elements co-precipitated with carbonates (S1), organic matter (S2) and amorphous Mn hydroxides (S3). According to the sediment guideline values, the sediment is polluted by, for instance, As and Hg in the inner area of the Murtosa Channel, Pb in the Espinheiro Channel, Aveiro City canals and Aveiro Harbour, and Zn in the northern area of the Ovar Channel. These sites are located near the source areas of pollutants and have the highest total available concentrations in each extracted phase. The total available concentrations of all toxic metals are however associated, firstly, with the production of amorphous Mn hydroxides in most of the areas and, secondly, with adsorption by organic compounds. The interplay of the different processes implies that not all of the sites near pollution sources have polluted surface sediment. The accumulation of metals depends on not only the pollution source but also the changing in the redox state of the sediments that may cause alterations in the sediment retention or releasing of redox-sensitive metals. Results of this work suggest that the biogeochemical processes may play a significant role in the increase of the pollutants in the sediment of the Aveiro Lagoon.

  4. Impact of clay mineral, wood sawdust or root organic matter on the bacterial and fungal community structures in two aged PAH-contaminated soils.

    Science.gov (United States)

    Cébron, Aurélie; Beguiristain, Thierry; Bongoua-Devisme, Jeanne; Denonfoux, Jérémie; Faure, Pierre; Lorgeoux, Catherine; Ouvrard, Stéphanie; Parisot, Nicolas; Peyret, Pierre; Leyval, Corinne

    2015-09-01

    The high organic pollutant concentration of aged polycyclic aromatic hydrocarbon (PAH)-contaminated wasteland soils is highly recalcitrant to biodegradation due to its very low bioavailability. In such soils, the microbial community is well adapted to the pollution, but the microbial activity is limited by nutrient availability. Management strategies could be applied to modify the soil microbial functioning as well as the PAH contamination through various amendment types. The impact of amendment with clay minerals (montmorillonite), wood sawdust and organic matter plant roots on microbial community structure was investigated on two aged PAH-contaminated soils both in laboratory and 1-year on-site pot experiments. Total PAH content (sum of 16 PAHs of the US-EPA list) and polar polycyclic aromatic compounds (pPAC) were monitored as well as the available PAH fraction using the Tenax method. The bacterial and fungal community structures were monitored using fingerprinting thermal gradient gel electrophoresis (TTGE) method. The abundance of bacteria (16S rRNA genes), fungi (18S rRNA genes) and PAH degraders (PAH-ring hydroxylating dioxygenase and catechol dioxygenase genes) was followed through qPCR assays. Although the treatments did not modify the total and available PAH content, the microbial community density, structure and the PAH degradation potential changed when fresh organic matter was provided as sawdust and under rhizosphere influence, while the clay mineral only increased the percentage of catechol-1,2-dioxygenase genes. The abundance of bacteria and fungi and the percentage of fungi relative to bacteria were enhanced in soil samples supplemented with wood sawdust and in the plant rhizospheric soils. Two distinct fungal populations developed in the two soils supplemented with sawdust, i.e. fungi related to Chaetomium and Neurospora genera and Brachyconidiellopsis and Pseudallescheria genera, in H and NM soils respectively. Wood sawdust amendment favoured the

  5. Pore Characteristics and Methane Adsorption of Clay Minerals in Shale Gas Reservoir%页岩气储层粘土矿物孔隙特征及其甲烷吸附作用

    Institute of Scientific and Technical Information of China (English)

    王茂桢; 柳少波; 任拥军; 田华

    2015-01-01

    The clay minerals are the main constituent minerals of the shale.It’s closely related with the occurrence and enrichment of shale gas.Because of its special crystal structure,clay minerals formed different types of pores between the crystal layers,in the internal mineral and between the mineral particles.The pore size, morphology and the specific surface area determine the methane adsorption capacity of the clay minerals.This paper reviews the occurrence of methane adsorption and various influence factors,such as pore structure,the water and organic matter in the pore.Different types of clay minerals are different in pore development and morphology.The round and slit micropores are most frequently found in smectite clay,which has the biggest total surface area and methane adsorption capacity.The mesoporous and macroporous are most developed in illite and kaolinite with the methane adsorption capacity belowing montmorillonite.Water and organic matters present in the pore of the clay minerals will also affect the methane adsorption capacity.Generally believed that water molecules will occupy the surface of pore,and resulting in a decrease of methane adsorption capacity of clay minerals.However,the specific effects of the soluble organic matter to the methane adsorption capacity of clay minerals are not clear yet.Finally, this paper indicates some of the issues to be explored in depth according to the needs of shale gas exploration.%粘土矿物是页岩的主要组成矿物,与页岩气的赋存和富集密切相关。粘土矿物因其特殊的晶体结构,在晶层之间、矿物内部以及矿物颗粒之间形成了不同类型的孔隙,这些孔隙的大小、形貌和比表面积决定着粘土矿物的甲烷吸附能力。为此,本文综述了粘土矿物的孔隙结构以及孔隙中的水和有机质对甲烷吸附性的影响,指出不同类型的粘土矿物孔隙发育与形貌特征存在差异,蒙脱石中多发育圆形、狭缝状的

  6. Clay resources in the Netherlands

    NARCIS (Netherlands)

    Meulen, M.J. van der; Maljers, D.; Gessel, S.F. van; Gruijters, S.H.L.L.

    2007-01-01

    Clay is a common lithology in the Dutch shallow subsurface. It is used in earth constructions such as dikes, and as raw material for the fabricationof bricks, roof tiles etc. We present a new national assessment of Dutch clay resources, as part of a project that provides mineral-occurrenceinformatio

  7. Clay resources in the Netherlands

    NARCIS (Netherlands)

    Meulen, M.J. van der; Maljers, D.; Gessel, S.F. van; Gruijters, S.H.L.L.

    2007-01-01

    Clay is a common lithology in the Dutch shallow subsurface. It is used in earth constructions such as dikes, and as raw material for the fabrication of bricks, roof tiles etc. We present a new national assessment of Dutch clay resources, as part of a project that provides mineral-occurrence informat

  8. Impact of medicated feed along with clay mineral supplementation on Escherichia coli resistance to antimicrobial agents in pigs after weaning in field conditions.

    Science.gov (United States)

    Jahanbakhsh, Seyedehameneh; Kabore, Kiswendsida Paul; Fravalo, Philippe; Letellier, Ann; Fairbrother, John Morris

    2015-10-01

    The aim of this study was to examine changes in antimicrobial resistance (AMR) phenotype and virulence and AMR gene profiles in Escherichia coli from pigs receiving in-feed antimicrobial medication following weaning and the effect of feed supplementation with a clay mineral, clinoptilolite, on this dynamic. Eighty E. coli strains isolated from fecal samples of pigs receiving a diet containing chlortetracycline and penicillin, with or without 2% clinoptilolite, were examined for antimicrobial resistance to 15 antimicrobial agents. Overall, an increased resistance to 10 antimicrobials was observed with time. Supplementation with clinoptilolite was associated with an early increase but later decrease in blaCMY-2, in isolates, as shown by DNA probe. Concurrently, a later increase in the frequency of blaCMY-2 and the virulence genes iucD and tsh was observed in the control pig isolates, being significantly greater than in the supplemented pigs at day 28. Our results suggest that, in the long term, supplementation with clinoptilolite could decrease the prevalence of E. coli carrying certain antimicrobial resistance and virulence genes.

  9. Clay Houses

    Science.gov (United States)

    Pedro, Cathy

    2011-01-01

    In this article, the author describes a project designed for fourth-graders that involves making clay relief sculptures of houses. Knowing the clay houses will become a family heirloom makes this lesson even more worth the time. It takes three classes to plan and form the clay, and another two to underglaze and glaze the final products.

  10. Porosity Investigation of Kosova's Clay

    OpenAIRE

    Makfire Sadiku; Naim Hasani; Altin Mele

    2011-01-01

    Problem statement: Acid activated clay minerals are used as catalysts in the desulphurization of crude oil or as catalyst carrier, as drilling mud, as bleaching earth. Approach: The efficiency of the acid activation can be described in two ways. As increase of the surface and as increase of the cumulative pore volume after the activation. Results: In different samples of the clay mineral the activation was done with different sulfuric acid concentrations for two and 3h. Afterwards the specifi...

  11. Bone Mineral Density Value in Kastamonu and Area of Turkish Society Women

    Directory of Open Access Journals (Sweden)

    Ahmet Aslan

    2013-05-01

    Full Text Available      Aim: Bone Mineral Density (BMD is influenced by such factors as ethnicity, genetics, gender, age, environment and geographical location. The aim of this study is to compare our own regional BMD means by using Lunar DPX in Kastamonu and area Women  Turksh Populaton with the Healty Turksh Populaton standardization data of used by the producer/importer company. Material and Method: Following the procedure of  informing the field-community about the study by the volunteering people, institutions and organizations, this cross-sectional study was carried out in Kastamonu province between the years 2009 and 2011. Of 510 healthy participants who applied to four  health care institutions which had Dual Energy X-Ray Absorptiometry devices (DEXA in Kastamonu province, were selected according to the inclusion criteria. The results of 510 cases using Lunar- DPX scanner, were evaluated in the study. Bone Densitometry scans were done according to national and international guidelines. BMD measurements were done at L2-L4 vertebrae and at the total proximal femur. The results were compared with Lunar DEXA reference study according to age groups. Compatibility of our data to normal distribution using the Kolmogorov- Smirnov test with SPSS 11.00 was checked. Parametric data analysis was performed by Independent groups t-test between means testing with statistical software package Statistic Calculator. P value <0.05 was considered significant. Results: In all age groups, except the peak vertebral and femoral BMD in 20-29 age group, the Lunar DEXA results were found to be lower than the vertebral and femoral BMD means that were given in the reference study which uses these means as the reference values for Turkish community. Additionally in these BMD measurements, peak vertebral and femoral BMD was the third decade. However BMD values diminished with aging. Discussion: The results of our study indicate that the Lunar DEXA vertebral and femoral BMD means

  12. Pb-Zn mineralization of Ali ou Daoud area (Central High Atlas, Morocco: characterisation of deposit and relationship with the clay assemblages

    Directory of Open Access Journals (Sweden)

    Daoudi, L.

    2008-12-01

    Full Text Available Zn-Pb-Fe ores in the Ali ou Daoud deposit (Central High Atlas are found as stratiform levels and as karst fillings in carbonate platforms facies of Bajocian age. Tectonic structures (e.g., synsedimentary faults played a relevant role in the ore emplacement. The dolomitic ore-related host-rock levels are characterized by the presence of kaolinite enrichment in clay levels in amounts directly related to the proportion of the clay minerals. The latter is evidenced by correlation between kaolinite and sulphide contents, suggesting that the installation of kaolinite and mineralisations would result from the same hydrothermal fluid.[Français] Dans les séries sédimentaires carbonatées d’Ali ou Daoud (Haut Atlas Central, les minéralisations à Zn, Pb et Fe en amas stratiformes forment les faciès de remplissage des karsts d’une plateforme carbonatée bajocienne. Le contrôle structural joue un rôle capital dans la localisation du gîte en bordure de plateforme sur des failles synsédimentaires. Dans les niveaux dolomitiques encaissants des minéralisations, les assemblages argileux sont caractérisés par la présence de kaolinite dont la teneur varie parallèlement avec celle du minerai. Ceci suggère que la mise en place de la kaolinite et des minéralisations résulterait du même fluide hydrothermal. [Español] En las series sedimentarias carbonatadas de Ali ou Daoud (Alto Atlas Central, las mineralizaciones de Zn, Pb y Fe aparecen en niveles estratiformes como facies de reemplazamiento de los karsts de una plataforma carbonatada Bajociense. El control estructural desempeña un papel crucial en la localización del yacimiento a lo largo de la plataforma sobre fallas sinsedimentarias. En los niveles dolomíticos que incluyen las mineralizaciones, las asociaciones arcillosas se caracterizan por la presencia de caolinita, cuyo contenido varía paralelamente al de la mineralización. Esto sugiere que la creación de caolinita y de la

  13. Adsorption of Three Phthalic Acid Esters on Different Clay Minerals%三种邻苯二甲酸酯在不同黏土矿物上的吸附

    Institute of Scientific and Technical Information of China (English)

    吴艳华; 周东美; 高娟; 司友斌

    2015-01-01

    Phthalic acid esters(PAEs)are widely used as plasticizers and are easily released into the environment, posing potential harms to human. Clay minerals are an important component of soil. After PAEs enter soils, the clay minerals would inevitably affect the transformation and fates of PAEs. Here we examined PAEs adsorption on clay minerals using two montmorillonite clays(FZ-10, SMF)and one kaolinite clay(Kao)as adsorbents that were saturated with K ions(K-FZ-10,K-SMF and K-Kao). Results showed that the adsorption of PAEs by clay minerals were in the following order:dimethyl phthalate(DMP)K-SMF>K-Kao. Both type and surface area of clay minerals contributed to the adsorption ability. Temperature rise reduced the adsorptions of three PAEs on K-FZ-10, K-SMF and K-Kao, indicating that the adsorption was exothermic and spontaneous. This study revealed that the type of clays, hydrophobicityof PAEs and temperature were three important factors affecting the adsorption of PAEs on clay minerals. The adsorption of PAEs onto soil could be used to predict the transportation in soil to some extent.%邻苯二甲酸酯类(PAEs)作为一类常见的增塑剂可以通过多种途径进入土壤,并在土壤中富集。黏土矿物是土壤的一个重要组分,对有机污染物的迁移有重要的作用。通过考察三种PAEs,即邻苯二甲酸二甲酯(DMP)、邻苯二甲酸二乙酯(DEP)和邻苯二甲酸正丁酯(DnBP)在改性之后的K+饱和黏土矿物(K-FZ-10,K-SMF和K-Kao)上的吸附行为,分析了黏土矿物类型、PAEs种类以及温度对吸附的影响。试验结果能较好地用Freundlich方程进行拟合,结果表明:PAEs的疏水性越强,固相-水分配系数(K d)越大, PAEs越容易被黏土矿物吸附;三种PAEs在黏土矿物上的吸附量均呈现DMPK-SMF>K-Kao,其与黏土矿物的表面积呈正相关。不同温度(4、10、20℃和30℃)的试验结果表明,黏土矿

  14. Cerium sequestration and accumulation in fractured crystalline bedrock: The role of Mn-Fe (hydr-)oxides and clay minerals

    Science.gov (United States)

    Yu, Changxun; Drake, Henrik; Mathurin, Frédéric A.; Åström, Mats E.

    2017-02-01

    This study focuses on the mechanisms of Ce sequestration and accumulation in the fracture network of the upper kilometer of the granitoid bedrock of the Baltic Shield in southeast Sweden (Laxemar area, Sweden). The material includes 81 specimens of bulk secondary mineral precipitates (;fracture coatings;) collected on fracture walls identified in 17 drill cores, and 66 groundwater samples collected from 21 deep boreholes with equipment designed for retrieval of representative groundwater at controlled depths. The concentrations of Ce in the fracture coatings, although varying considerably (10-90th percentiles: 67-438 mg kg-1), were frequently higher than those of the wall rock (10-90th percentiles: 70-118 mg kg-1). Linear combination fitting analysis of Ce LIII-edge X-ray absorption near-edge structure (XANES) spectra, obtained for 19 fracture coatings with relatively high Ce concentrations (⩾145 mg kg-1) and a wide range of Ce-anomaly values, revealed that Ce(IV) occurs frequently in the upper 10 m of the fracture network (Ce(IV)/Cetotal = 0.06-1.00 in 8 out of 11 specimens) and is mainly associated with Mn oxides (modeled as Ce oxidatively scavenged by birnessite). These features are in line with the strong oxidative and sorptive capacities of Mn oxide as demonstrated by previous studies, and abundant todorokite and birnessite-like Mn oxides identified in 3 out of 4 specimens analyzed by Mn K-edge X-ray absorption spectroscopy (XAS) in the upper parts of the fracture network (down to 5 m). For a specimen with very high Ce concentration (1430 mg kg-1) and NASC-normalized Ce anomaly (3.63), the analysis of Ce XANES and Mn XAS data revealed (i) a predominance of Ce oxide in addition to Ce scavenged by Mn oxide; and (ii) a large fraction of poorly-crystalline hexagonal birnessite and aqueous Mn2+, suggesting a recent or on-going oxidation of Mn2+ in this fracture. In addition, the Ce oxide precipitates on this fracture observed by in situ SEM-EDS contained

  15. Mineralogy and geotechnical characteristics of some pottery clay

    OpenAIRE

    Mujib Olamide ADEAGBO; Samuel Akinlabi OLA; Olumide Oluwapelumi OJURI

    2016-01-01

    The physical properties of soils, which are tremendously influenced by the active clay minerals in soil, are of great importance in geotechnical engineering. This paper investigates the clay-sized particles of the Igbara-Odo pottery clay, and compares results obtained with available data on the bulk sample, to determine their correlation and underline the dependence of the geotechnical properties of the bulk clay material on the clay-sized particles. The bulk clay sample consists of 52% sand-...

  16. Formation Mechanism and Distribution of Clay Minerals of Deeply Tight Siliciclastic Reservoirs%致密碎屑岩中粘土矿物的形成机理与分布规律

    Institute of Scientific and Technical Information of China (English)

    张哨楠; 丁晓琪; 万友利; 熊迪; 朱志良

    2012-01-01

    随着油气勘探开发的逐渐深入,深层致密碎屑岩油气藏所占比例越来越高.致密碎屑岩油气藏勘探的重点往往是寻找高效储层的发育规律,而高效储层的形成机理与成岩过程中的粘土矿物有着密切的关系,致密碎屑岩储层中常见的粘土矿物有高岭石、绿泥石、混层粘土和伊利石.通过铸体薄片、扫描电镜、背散射等研究手段,分析不同类型粘土矿物的形成机理,结合沉积相和层序地层,对其分布规律进行研究.研究结果表明,成岩粘土矿物的形成与储层碎屑颗粒的成分、气候、沉积环境及古温度等有密切关系.海(湖)平面变化对成岩阶段早期形成的粘土矿物具有明显控制作用,随后这些早期形成的粘土矿物影响着成岩晚期的粘土矿物类型、含量和分布.碎屑岩颗粒组分、沉积相和层序地层相结合,可以有效地预测碎屑岩储层中粘土矿物的形成机理和分布规律,为深层高效储层的预测提供理论基础.%With the development of petroleum exploration and exploitation, the proportion of deeply buried tight siliciclastic reservoirs is increasing significantly. The key to successful exploration in tight siliciclastic reservoirs is usually to find the growing law of the efficient reservoirs. However, there is a close relationship between formation mechanism and diagenetic clay minerals. Kaolinite, chlorite, mixed-layer illite-smectite and illite are common clay minerals in tight siliciclastic reservoirs. Formation mechanism and distribution of clay minerals can be studied by thin section, SEM and BSE, with consideration of sedimentary facies and sequence stratigraphy. The results show that formation of clay minerals are influenced by framework grains composition, climate, depositional environment, temperature, and so on. Clay minerals formed in early diagenesis can be controlled by sea level changes, however, which can influence late diagenetic clay

  17. Atypical subtrochanteric and diaphyseal femoral fractures: report of a task force of the American Society for Bone and Mineral Research.

    Science.gov (United States)

    Shane, Elizabeth; Burr, David; Ebeling, Peter R; Abrahamsen, Bo; Adler, Robert A; Brown, Thomas D; Cheung, Angela M; Cosman, Felicia; Curtis, Jeffrey R; Dell, Richard; Dempster, David; Einhorn, Thomas A; Genant, Harry K; Geusens, Piet; Klaushofer, Klaus; Koval, Kenneth; Lane, Joseph M; McKiernan, Fergus; McKinney, Ross; Ng, Alvin; Nieves, Jeri; O'Keefe, Regis; Papapoulos, Socrates; Sen, Howe Tet; van der Meulen, Marjolein C H; Weinstein, Robert S; Whyte, Michael

    2010-11-01

    Reports linking long-term use of bisphosphonates (BPs) with atypical fractures of the femur led the leadership of the American Society for Bone and Mineral Research (ASBMR) to appoint a task force to address key questions related to this problem. A multidisciplinary expert group reviewed pertinent published reports concerning atypical femur fractures, as well as preclinical studies that could provide insight into their pathogenesis. A case definition was developed so that subsequent studies report on the same condition. The task force defined major and minor features of complete and incomplete atypical femoral fractures and recommends that all major features, including their location in the subtrochanteric region and femoral shaft, transverse or short oblique orientation, minimal or no associated trauma, a medial spike when the fracture is complete, and absence of comminution, be present to designate a femoral fracture as atypical. Minor features include their association with cortical thickening, a periosteal reaction of the lateral cortex, prodromal pain, bilaterality, delayed healing, comorbid conditions, and concomitant drug exposures, including BPs, other antiresorptive agents, glucocorticoids, and proton pump inhibitors. Preclinical data evaluating the effects of BPs on collagen cross-linking and maturation, accumulation of microdamage and advanced glycation end products, mineralization, remodeling, vascularity, and angiogenesis lend biologic plausibility to a potential association with long-term BP use. Based on published and unpublished data and the widespread use of BPs, the incidence of atypical femoral fractures associated with BP therapy for osteoporosis appears to be very low, particularly compared with the number of vertebral, hip, and other fractures that are prevented by BPs. Moreover, a causal association between BPs and atypical fractures has not been established. However, recent observations suggest that the risk rises with increasing duration of

  18. 几种土壤及黏土矿物对多氯联苯吸附特性的研究%Adsorption Charcteristics of PCBs in Soils and Clay Minerals

    Institute of Scientific and Technical Information of China (English)

    司雄元; 王寅; 陈倩倩; 司友斌

    2012-01-01

    采用批量平衡试验,研究了不同土壤及长黏土矿物对多氯联苯吸附特性。结果表明:多氯联苯浓度范围为0.25~5.0mg L-1时,不同土壤及黏土矿物对多氯联苯的吸附均能用Freundlich方程很好地拟合,随着溶液中多氯联苯浓度的增加,土壤及黏土矿物对多氯联苯的吸附量增加;几种土壤对多氯联苯吸附量大小顺序为:红壤〉黄褐土〉砂姜黑土,土壤有机质、粘粒等对多氯联苯吸附起主要作用,土壤更易吸附高氯代PCB77;黏土矿物对多氯联苯吸附量大小顺序为:纳米蒙脱石〉纳米SiO2〉凹凸棒石,黏土矿物吸附多氯联苯能力的大小与黏土矿物的比表面积、粒径、层状结构等有关;多氯联苯本身分子的大小影响其在黏土矿物上的吸附;土壤中添加黏土矿物可以提高对多氯联苯的吸附。%Adsorption characteristics of PCBs in soils and clay minerals were studied using the batch equilibration technique.Results showed that the adsorption of PCBs conformed to the Freundlich equation when the concentrations of PCBs were from 0.25 mg L-1 to 5.0 mg L-1,and the adsorption of PCBs in soils and clay minerals increased with the increase of initial concentration.The adsorption capacity of soils for PCBs followed the order red soil yellow brown soil shajiang black soil.The contents of organic matter and clay in soil governed adsorption of PCBs,and the high chlorine of PCBs were easier to be absorbed by soils.The adsorption capacity of clay minerals for PCBs followed the order nanometer-sized montmorillonite nanometer-sized SiO2 attapulgite.The adsorption ability of clay minerals for PCBs related to the surface area,diameter and layered structure of clay minerals.The molecular size of PCBs also affected the adsorption.Adding clay minerals to soil could improve the adsorption ability.

  19. Minerals

    Directory of Open Access Journals (Sweden)

    Vaquero, M. P.

    1998-08-01

    Full Text Available The possible changes in the mineral composition of food during frying could be the consequence of losses by leaching, or changes in concentrations caused by exchanges between the food and culinary fat of other compounds. The net result depends on the type of food, the frying fat used and the frying process. Moreover, the modifications that frying produces in other nutrients could indirectly affect the availability of dietary minerals. The most outstanding ones are those that can take place in the fat or in the protein. With respect to the interactions between frying oils and minerals, we have recent knowledge concerning the effects of consuming vegetable oils used in repeated fryings of potatoes without turnover, on the nutritive utilization of dietary minerals. The experiments have been carried out in pregnant and growing rats, which consumed diets containing, as a sole source of fat, the testing frying oils or unused oils. It seems that the consumption of various frying oils, with a polar compound content lower or close to the maximum limit of 25% accepted for human consumption, does not alter the absorption and metabolism of calcium, phosphorous, iron or copper. Magnesium absorption from diets containing frying oils tends to increase but the urinary excretion of this element increases, resulting imperceptible the variations in the magnesium balance. The urinary excretion of Zn also increased although its balance remained unchanged. Different studies referring to the effects of consuming fried fatty fish on mineral bioavailability will also be presented. On one hand, frying can cause structural changes in fish protein, which are associated with an increase in iron absorption and a decrease in body zinc retention. The nutritive utilization of other elements such as magnesium, calcium and copper seems to be unaffected. On the other hand; it has been described that an excess of fish fatty acids in the diet produces iron depletion, but when fatty

  20. Instrumental characterization of clay by XRF, XRD and FTIR

    Indian Academy of Sciences (India)

    Preeti Sagar Nayak; B K Singh

    2007-06-01

    Instrumental characterizations of the clay were performed by different techniques such as XRF, XRD and FTIR. XRF shows the chemical compositions of the clay where Al-oxide and silica oxide are present in major quantity whereas XRD confirms the presence of these minerals in clay. FTIR studies show the presence of quartz, alumina, haematite and different mineral matters.

  1. Deglacial Record in the Illinois River Valley Explains Asynchronous Phases of Meltwater Pulses and Clay Mineral Excursions in the Gulf of Mexico

    Science.gov (United States)

    Wang, H.

    2014-12-01

    One prominent event of the Bølling/Allerød (B/A) interstadial was the large meltwater release to global oceans. The Laurentide Ice Sheet (LIS) is usually considered the main source. But, the large LIS meltwater discharge conflicts with the marine record showing an active North Atlantic meridional overturning circulation (AMOC) during the B/A interval. Continuous dune-lacustrine successions in the Illinois River Valley (IRV) have shown complete records of the last deglacial chronozones. Their grain-size distributions and accurate B/A age 14C dates of plant fossils from 15 m deep lacustrine sediment in the IRV suggest that most of the IRV and parts of the adjacent upland were inundated by water. The inundation was caused by a sediment dam interpreted to have been constructed and followed by a breach at the confluence of the Mississippi and Illinois Rivers during the B/A interval due to sediment mobilization by the large meltwater release. The grain size distributions correlate with meltwater pulses and mineralogical excursions in sediments from the Gulf of Mexico (GOM) very well. The blockage and release of illite and chlorite rich fine-grained sediments from the Lake Michigan basin changed the relative abundance of clay minerals and thus the ratio of smectite/(illite + chlorite) in the sediment of the GOM. This finding explains why the meltwater episodes from the LIS and the associated detrital discharges are not synchronous in the sediments in the GOM. The finding also ties meltwater pulses and associated detrital discharges in the GOM closely to the LIS discharges via the Mississippi River Valley on chronozonal scales. Three arguments can be made from this result: 1) unaffected AMOC during B/A interval resulted potentially from the hyperpycnal inflow into the GOM floor; 2) limited volume of the meltwater discharge did not significantly influence the AMOC; and 3) the freshwater input into the GOM from the LIS at this particular location did not significantly

  2. Characterization of some clay deposits in South West Nigeria

    OpenAIRE

    2014-01-01

    Clay minerals are the most important industrial minerals whose application is dependent on its structure and chemical composition. Mineralogical, chemical compositions, phase constitutions, and microstructural morphology of certain clay minerals from three different deposits in south western Nigeria were investigated using state-of-the-art equipment. These were done with the intention of determining the appropriate application for the clay minerals. It was observed that the major phases in th...

  3. A comparative study on the illite crystallinity and the clay mineral reflectance spectral index for subdividing the very low-grade metamorphic belt along the Lizhou-Hekou geological section in the Youjiang sedimentary basin, Guangxi,China

    Institute of Scientific and Technical Information of China (English)

    YAN Shouxun

    2004-01-01

    To examine the application potential of hyperspectral remote sensing techniques in classifying very low-grade metamorphic belts, the composition of clay minerals and the cyrstallinity of illite from mudstones were measured using XRD and VIS-SWIR (400-2500 nm) reflectance spectroscopy. Based on the illite cyrstallinity, Kubler Index (KI), the Early Triassic LuoLou Group and the Middle Triassic lower Baifeng Formation were classified as the lower Epizone with KI△2θ° ranging from 0.22 to 0.25, the upper Baifeng Formation as upper anchizone with KI△2θ°ranging from 0.26 to 0.33, and the Hekou Formation as lower anchizone with KI△2θ° ranging from 0.38 to 0.40. According to a KI△2θ° value of 0.43, it is possible that there may exist a local diagenetic zone in the upper strata. The illite cyrstallinity Kubler index and the metamorphic grade increase from the bottom to the top of the stratigraphic sequence. The metamorphic grade boundaries nearly match the stratigraphic boundaries, indicating a burial metamorphism nature for the stratigraphic sequence. From the bottom to the top of the sequence, the spectral absorption band center of clay minerals from fresh rocks is around 2200 nm. The absorption band centers change towards shorter wavelengths: the Luolou Group being at 2220 nm, the Baifeng Formation at 2217-2213 nm, the lower member of the Hekou Formation at 2214-2206 nm, and the upper member of the Hekou Formation at 2205-2197 nm. The spectral absorption band center of illite shows the same change pattern. These results indicate that very low-grade metamorphic belts can be subdivided using spectral indices of clay minerals, which are measured by using field portable spectroradiometers. However, it may not work well with satellite and airborne sensors.

  4. Availability of mineral resources for society; Disponibilidad y retos actuales de los recursos minerales para la sociedad

    Energy Technology Data Exchange (ETDEWEB)

    Price, J. G.; Espi, J. A.

    2014-06-01

    Trends in global mineral production and expanding uses of mineral resources foretell a bright future, although with significant challenges, for exploration and development. Demand for mineral resources is likely to remain high and grow to meet increases in world population and standards of living. Significant challenges include meeting future demand with new discoveries and developing the resources in environmentally, socially, and economically sustainable ways. A historical perspective from the last 50 years on finding new mineral districts, discovering new types of ore deposits, and using new technologies in exploration suggests that the world will not run out of mineral resources. It is likely that substitution and recycling will play increasingly major roles in meeting global mineral demand. New technologies for ocean mining will help add to the resource base. Historical perspectives also suggest that mining scams will continue, and environmental, health, and safety concerns will be major factors in deciding where future mines will be located and how they will be operated. (Author)

  5. Probing the water interactions in clay

    Energy Technology Data Exchange (ETDEWEB)

    Powell, D.H. [Lausanne Univ., Lausanne (Switzerland); Fischer, H.E. [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France); Skipper, N.T. [Univ. College, London (United Kingdom)

    1999-11-01

    Clays, the microscopic mineral fraction of soils, are probably the most important substrate for interactions between water, the mineral world and the biosphere. A knowledge of the structuring of water and hydrated metal ions near clays surfaces is of importance in environmental science, including toxic and radioactive waste disposal, and in the industrial application of clays. The smectite clays, with their large hydrated internal surface areas represent excellent model systems for the interactions of aqueous phases with solid surface. We present the results of neutron diffraction experiments using isotopic substitutions to probe the structure in the aqueous interlayer region of Li-montmorillonite. (authors) 6 refs., 3 figs.

  6. 粘土矿物固定化微生物对土壤中阿特拉津的降解研究%Biodegradation of Atrazine in Soils by Clay Minerals Immobilized a Degradation Bacterium

    Institute of Scientific and Technical Information of China (English)

    汪玉; 王磊; 司友斌; 孟雪梅

    2009-01-01

    Biodegradation of atrazine in soils by clay minerals immobilized a degradation bacterium were studied. The bacterium which was isolated from activated sludge by enrichment using atrazine as sole source of carbon and nitrogen was preliminarily identified as Ochrobac-trum sp., according to its physiological-biochemical characteristics, photos of ESEM and the similarity analysis of its 16S rDNA gene sequence. The strains growed well on clay minerals, and reached logarithmic phase at 48 h. The degradation rate of atrazine was larger signifi-cally when adding degradation bacteria into soils. The biodegradation capacity by immobilized microorganism on clay minerals was improved compared with free microorganism. The smaller the particle size of clay minerals, the more the biodegradation of atrazine. The effect of immobilized nano-clay minerals was better than corresponding clays. The degradation of atrazine were 42.47%, 46.19%, 56.31 % respectively, after adding free microorganism into vertisol, alfisol and red soil on 28 d. When adding immobilized microorganism by montmorillonite, nano-mont-morillonite, the degradation of atrazine were 52.16%, 63.97% in vertisol, 59.28%, 63.91% in alfisol, and 68.03%, 76.59% in red soil. The degradation of atrazine in the soil without microorganism was 29.16% in vertisol, 30.63% in alfisol, 41.47% in red soil. Atrazine degradation in soils could be described by first-order kinetic equation. The effect of degradation varied from different soils. The(t_(1/2) of atrazine was 36.9 d in red soil, 49.1 d in vertisol, and 55.0 d in alfisol without microorganism. When adding immobilized microorganism by nano-montmorillonite, half-life was 16.3 d, 25.3 d, 21.7 d respectively.%以粘土矿物为载体,采用吸附挂膜法对已筛选的阿特拉津降解菌株进行固定化,并应用固定化微生物降解土壤中的阿特拉津.结果表明,该菌株在粘土矿物上生长良好,根据菌种生理生化特性、

  7. Preparation and characterization of polymer nanocomposites based on chitosan and clay minerals; Preparacao e caracterizacao de nanocompositos polimerico baseados em quitosana e argilo minerais

    Energy Technology Data Exchange (ETDEWEB)

    Fiori, Ana Paula Santos de Melo; Gabiraba, Victor Parizio; Praxedes, Ana Paula Perdigao [Instituto Federal de Alagoas (IFAL), Marechal Deodoro, AL (Brazil); Nunes, Marcelo Ramon da Silva; Balliano, Tatiane L.; Silva, Rosanny Christhinny da; Tonholo, Josealdo; Ribeiro, Adriana Santos, E-mail: aribeiro@qui.ufal.br [Universidade Federal de Alagoas (UFAL), Maceio, AL (Brazil)

    2014-09-15

    In this work nanocomposites based on chitosan and different clays were prepared using polyethyleneglycol (PEG) as plasticizer. The samples obtained were characterized by Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), thermogravimetric analysis (TGA/DTG) and by mechanical characterization (tensile test) with the aim of investigating the interactions between chitosan and clay. The nanocomposite films prepared using sodium bentonite (Ben) showed an increase of 81.2% in the maximum tensile stress values and a decrease of 16.0% in the Young’s modulus when compared to the chitosan with PEG (QuiPEG) films, evidencing that the introduction of the clay into the polymer matrix provided a more flexible and resistant film, whose elongation at break was 93.6% higher than for the QuiPEG film. (author)

  8. Um método simples de caracterização de argilominerais por difração de raios X A simple method for the characterization of clay minerals by X-ray diffraction

    Directory of Open Access Journals (Sweden)

    A. P. F. Albers

    2002-03-01

    Full Text Available A técnica de difração de raios X tem sido amplamente utilizada para a determinação de fases cristalinas em materiais cerâmicos. Em argilas, a grande quantidade de quartzo e seu elevado grau de orientação dificultam a identificação e caracterização das demais fases presentes. Baseando-se no princípio da sedimentação, é apresentado neste trabalho um método simples e confiável para a determinação de argilominerais em materiais argilosos.The X-ray diffraction technique has been widely used for the determination of crystalline phases in ceramic materials. The large content and high degree of orientation of quartz in clays pose a problem to the identification and characterization of the remaining phases. A simple and reliable method for the determination of clay minerals in clay materials, based on the sedimentation principle, is presented.

  9. 气候环境变化研究中影响粘土矿物形成及其丰度因素的讨论%A discussion on the factors affecting formation and quantity of clay minerals in climatic and environmental researches

    Institute of Scientific and Technical Information of China (English)

    孙庆峰; Christophe Colin; 陈发虎; 张家武

    2011-01-01

    Clay minerals have such main types as illite, chlorite, smectite and kaolinite.They could record rich information of climatic and environmental changes during their formation and hence are good proxies in climatic and environmental study.Many factors such as tectonic movement, climate, basin size, surface parent rocks, soils, vegetative cover, landscape, water media properties, wind and diagenesis, affect the clay mineral formation.The types and quantity of clay minerals in strata depend on these factors in varying degrees.Tectonic movement and climate are two primary factors which dominate the types and quantity and control other secondary factors which influence clay mineral formation.It is very difficult and unsuitable to analyze climatic and environmental changes during the tectonic movement phase only by clay minerals.For a long geological time which has tectonic movement, sedimentary facies and palaeogeography must be used to decipher paleogeography and plaeo-environment information.However, under stable tectonic movement, which spans usually a short geological time, other information factors keep stable and clay minerals are formed mainly through climatic factors.They record the real information of climate and environment changes and hence can be used as climatic proxies.Basin change of climate and environment could be inverted.So, climate is the key factor for forming clay minerals and determining their amounts.Strata-tectonic analysis must be done when clay minerals are used to decipher climatic and environmental information.In a word, when tectonic movement is stable, climate becomes the dominate factor affecting clay mineral formation.The other secondary factors keep invariant and clay minerals carry the major climatic information, and they can be used to decipher climatic and environmental history.The mixture of clay minerals caused by ground hydrographic systems affects the signal clearness of clay minerals carrying major climatic information and

  10. DISTRIBUTION PATTERN OF CLAY MINERALS IN SURFACE SEDIMENTS OF SOUTH YELLOW SEA AND THEIR PROVENANCE%南黄海表层沉积物黏土矿物分布及物源

    Institute of Scientific and Technical Information of China (English)

    蓝先洪; 张宪军; 刘新波; 李日辉; 张志珣

    2011-01-01

    通过对南黄海表层沉积物295个站位的黏土矿物含量分析,研究了南黄海表层沉积物黏土矿物的组合特征、分布规律及与物质来源的关系.南黄海表层沉积物中伊利石含量最高,蒙脱石和高岭石含量次之,绿泥石含量最低;黏土矿物的组合类型以伊利石-蒙脱石-高岭石-绿泥石型为主,伊利石-高岭石-蒙脱石-绿泥石型次之;南黄海表层沉积物黏土矿物主要为陆源成因,物质主要来源于黄河和长江的供给.现代黄河物质及老黄河物质主要沉积于南黄海的西部和中部;长江物质主要在南黄海的西南和中北部区域沉积,东部物质反映来自朝鲜半岛的物质对南黄海东部的作用.%The clay minerals composition of the surface sediments in the South Yellow Sea from 295 stations were studied with focus on clay assemblages and their distribution pattern as well as provenance. The research results show that illite dominates in surface sediments of the South Yellow Sea with smectite or kao-linite as the second and chlorite the lowest. The assemblage of illite-smectite-kaolinete-chlorite is the main type of the clay minerals assemblage in the area, followed by the illite-kaolinete-smectite-chlorite assemblage. Clay minerals are mainly from the Yellow River and Yangtze River. Materials from both the recent and the ancient Yellow River deposited mainly in the western, middle part of the South Yellow Sea, while the substance from the Yangtze River deposited mainly in the southwestern and southern parts. In the eastern part of the study area, an influence of the material from the Korean peninsula was observed.

  11. Application of clay minerals from Cayo Guan, Cuba, as sorbents of heavy metals and ceramic raw materials; Aplicaciones de los minerales arcillosos de Cayo Guan, Cuba, como adsorbentes de metales pesados y materia prima ceramica

    Energy Technology Data Exchange (ETDEWEB)

    Fonseca, D.; Barba, F.; Callejas, P.; Recio, P.

    2012-11-01

    It has been studied by Analysis Heating Microscope Optical the behaviour of some kaolinitic clays from a reservoir of Cayo Guan rich in iron oxides and low silica content proving to be a refractory materials whose softening appears after 1500 degree centigrade. It has obtained the workability diagram of the different clay minerals calculating the plasticity by the method of Casagrande spoon; only one of the samples is in the area suitable for extrusion. Vitrification diagrams report that the capacity of water absorption is <0.6 % when the temperature of 1400 degree centigrade is achieved. We have designed a program to calculate compositions of porcelain stoneware prepared from these modified clays adding low-cost raw materials that facilitate the formation of glassy phase ((potassium feldspar and glass cullet) and/or increase the silica (sand and diatomaceous earth used as filters in the brewing industry). With one of these compositions, prepared in the laboratory (60 % of clay, 30 % feldspar and 10 % of diatomaceous earth), calcined at 1250 degree centigrade with a heating rate of 15 degree centigrade/min, the results were: water absorption 0.8 %, and linear shrinkage 21 % without any deformation observed. These clays have been treated with acid to eliminate its high iron content and study its application as an sorbent of heavy metals as Cd{sup 2}+, Cr{sup 3}+. The results of the immobilization of these elements have been compared with those obtained with thermally activated vermiculite at 800 degree centigrade, showing that the treated samples show sorption of both cadmium and chromium below the vermiculite, but the non-treated ones are suitable to remove chromium; this is because these clays do not contain in its composition exchangeable ions (Ca{sup {sub 2}} +, Mg{sup 2} +, Na{sup +}, K{sup +}), and even if they are chemically activated only the presence of Fe ions is which produces form bindings (Cr{sub x}.Fe{sub 1}-x) (OH){sub 3} which favor Cr sorption

  12. Clay at Nili Fossae

    Science.gov (United States)

    2006-01-01

    This image of the Nili Fossae region of Mars was compiled from separate images taken by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) and the High-Resolution Imaging Science Experiment (HiRISE), two instruments on NASA's Mars Reconnaissance Orbiter. The images were taken at 0730 UTC (2:30 a.m. EDT) on Oct. 4, 2006, near 20.4 degrees north latitude, 78.5 degrees east longitude. CRISM's image was taken in 544 colors covering 0.36 to 3.92 micrometers, and shows features as small as 18 meters (60 feet) across. HiRISE's image was taken in three colors, but its much higher resolution shows features as small as 30 centimeters (1 foot) across. CRISM's sister instrument on the Mars Express spacecraft, OMEGA, discovered that some of the most ancient regions of Mars are rich in clay minerals, formed when water altered the planet's volcanic rocks. From the OMEGA data it was unclear whether the clays formed at the surface during Mars' earliest history of if they formed at depth and were later exposed by impact craters or erosion of the overlying rocks. Clays are an indicator of wet, benign environments possibly suitable for biological processes, making Nili Fossae and comparable regions important targets for both CRISM and HiRISE. In this visualization of the combined data from the two instruments, the CRISM data were used to calculate the strengths of spectral absorption bands due to minerals present in the scene. The two major minerals detected by the instrument are olivine, a mineral characteristic of primitive igneous rocks, and clay. Areas rich in olivine are shown in red, and minerals rich in clay are shown in green. The derived colors were then overlayed on the HiRISE image. The area where the CRISM and HiRISE data overlap is shown at the upper left, and is about 5 kilometers (3 miles) across. The three boxes outlined in blue are enlarged to show how the different minerals in the scene match up with different landforms. In the image at the upper right

  13. Pb-Zn mineralization of the Ali ou Daoud area (Central High Atlas, Morocco): characterisation of the deposit and relationships with the clay assemblages; Mineralisation Pb-Zn du type MVT de la region d'Ali ou Daoud (Haut Atlas Central, Maroc): caracterisations du gite et relations avec les corteges de mineraux argileux

    Energy Technology Data Exchange (ETDEWEB)

    Mouguina, E. M.; Daoudi, L.

    2008-07-01

    Zn-Pb-Fe ores in the Ali ou Daoud deposit (Central High Atlas) are found as stratiform levels and as karst fillings in carbonate platforms facies of Bajocian age. Tectonic structures (e.g., syn sedimentary faults) played a relevant role in the ore emplacement. The dolomitic ore-related host-rock levels are characterized by the presence of kaolinite enrichment in clay levels in amounts directly related to the proportion of the clay minerals. The latter is evidenced by correlation between kaolinite and sulphide contents, suggesting that the installation of kaolinite and mineralizations would result from the same hydrothermal fluid. (Author) 55 refs.

  14. Argilas especiais: o que são, caracterização e propriedades Special clays: what they are, characterization and properties

    OpenAIRE

    Antonio C. Vieira Coelho; Pérsio de Souza Santos; Helena de Souza Santos

    2007-01-01

    Special clays are a group of clays different from the large volume of clay mineral products named "Industrial Clays": kaolins, ball clays, refractory clays, bentonites, fuller's earths, common clays. Two groups of special clays exist: rare, as in the case of hectorite and sepiolite and restricted areas, as in the case of white bentonite, halloysite and palygorskite (attapulgite). A review is given of the most important producers of the special clays and their properties in the Western World, ...

  15. Mineralogical analysis of Brazilian ceramic sedimentary clays used in red ceramic Análise mineralógica de argilas sedimentares brasileiras usadas em cerâmica vermelha

    Directory of Open Access Journals (Sweden)

    G. P. Souza

    2005-12-01

    Full Text Available The present work focuses on the mineralogical analysis of sedimentary clay material samples collected from deposits located in the Campos dos Goytacazes-RJ (Brazil region. These samples are representative and widely used by the ceramic plants in production of bricks and roofing tiles. The samples were selected with the objective of analyzing their characteristics regarding chemical composition, loss on ignition, X-ray diffraction, morphology, particle size, plasticity and thermal analysis. The sedimentary red clays have low amount of SiO2, high amount of Al2O3, and high loss on ignition. In addition, it was found that the character of the clays is typically kaolinitic.O presente trabalho é focado sobre a análise mineralógica de amostras de argilas sedimentares coletadas de depósitos localizados na região de Campos dos Goytacazes-RJ (Brasil. Estas amostras são representativas e largamente usadas na produção de blocos cerâmicos e telhas. As amostras foram selecionadas com o intuito de analisar suas características com respeito à composição química, perda ao fogo, difração de raios X, morfologia, análise de tamanho de partícula, plasticidade e análise térmica. As argilas vermelhas sedimentares têm baixa quantidade de SiO2, alta quantidade de Al2O3 e alta perda ao fogo. Além disso, foi determinado que o caráter das argilas é tipicamente caulinítico.

  16. 可可西里盐湖表层沉积物中粘土矿物的环境信息%Environmental information of clay minerals in salt lake surface sediments of Hol Xil area

    Institute of Scientific and Technical Information of China (English)

    高翔; 彭强; 蔡敏; 邸迎伟; 方勤方; 马鸿文; 鲁安怀

    2012-01-01

    通过对可可西里盐湖表层沉积物中粘土矿物的研究,以期获得近年来湖区的某些环境信息.研究结果表明:沉积物中的粘土矿物主要为伊利石和绿泥石,非粘土矿物主要为石英、方解石和长石以及少量白云石、文石、闪石和石膏等.样品中<2μm的粘土矿物以伊利石和绿泥石为主,局部样品含少量有序伊/蒙混层.根据样品分布特点和粘土矿物的组合类型,将样品划分为3个区域:1区和3区的矿物组合为伊利石、绿泥石和有序伊/蒙混层;2区为伊利石和绿泥石,无伊像混层矿物.其中1区和3区样品的结晶度(IC)范围为0.41~0.59,均值为0.51;2区样品的结晶度范围为0.25~0.40,均值为0.34,明显低于1区和3区,说明2区样品中的伊利石具有更高的结晶度.样品的伊利石化学指数(CI)均小于0.5,表明该伊利石为富Fe-Mg伊利石,主要是物理风化作用的结果.伊利石和绿泥石作为主要粘土矿物反映了近年来整个湖区的环境以干冷为主,局部区域(1区和3区)出现的少量有序I/S混层矿物则指示在短期内曾经历过短暂的干湿交替环境.此外,在酸性介质条件下,少量伊利石发生弱水解作用导致晶格中的K+淋失,并转化为伊/蒙混层矿物,同时也降低了伊利石的结晶度.%Clay minerals of surface sediments in the salt lakes of Hoi Xil area were studied in this paper with the purpose of obtaining some recent environmental information of the lakes. The results show that clay minerals are illite and chlorite in surface sedimentary samples, whereas non-clay minerals mainly include quartz, calcite and feldspar together with small amounts of dolomite, aragonite, amphibole and gypsum. Clay minerals with particle sizes smaller than 2 μm in samples are illite (65% ~82% ) and chlorite (13% ~35% ), and small amounts of ordered Illite/Smectite (I/S) mixed layer (4%~15%) also exists in local areas. According to the distribution of

  17. 黏土矿物高温热变及对储层孔隙结构的影响%The Influence of Thermal Alteration of Clay Minerals on Pore Sturcture

    Institute of Scientific and Technical Information of China (English)

    路言秋

    2015-01-01

    The high clay content and the expansion of clay mineral consisting mainly of calcium montmorillonite in 1st Member Shahejie Formation in Jinjia Oilfield cause strong water sensitivity,which restrict the thermal recovery, so, the study for thermal alteration of clay mineral is needed to make clear how to effect on the pore structure.The experiments include the crystal axial range of test sample, analysis of aqueous solutes,X-ray diffraction, SEM and oil-bearing thin section after the tests in high temperature in autoclave show that under the condition of high temper-ature above 100 ℃, with temperature rising, montmorillonite crystal spacing is reduced and the dilatability is de-creased, which is little harm to pore structure;the corrosion and conversion to form new mineral grain of montmoril-lonite and other diagenetic minerals under the condition of high temperature filling large and medium pore throat in-to micro-pore throat lead to deterioration of pore structure.Through the understanding, it is clear that the key factors affecting the pore structure of the reservoir is blockage of the new mineral particles transformed by calcium montmo-rillonite and other diagenetic mineral under high temperature condition rather than its expansion.%金家油田沙一段稠油油藏储层黏土矿物主要为钙基蒙脱石,含量高且具膨胀性,导致储层具强水敏性,制约油藏热采开发,因此需要对黏土矿物高温热变特征进行研究,明确其对储层孔隙结构影响方式。高压釜高温物模实验后样品晶间距、溶质分析、X衍射、扫描电镜等资料分析表明:在100℃以上的高温条件下,随温度升高,蒙脱石晶间距减小,膨胀性减弱,对储层孔隙结构的危害不大;蒙脱石及其他成岩矿物高温条件下发生溶蚀、转化形成新的矿物颗粒充填改造大、中孔喉,变成微、小孔喉,导致储层孔隙结构变差。以此,明确了高温条件下

  18. 农业利用对东北黑土黏粒矿物组成及养分的影响%Effect of Agricultural Use on Clay Minerals and Nutrient of Black Soil in Northeast of China

    Institute of Scientific and Technical Information of China (English)

    郑庆福; 赵兰坡

    2011-01-01

    为了明确农业利用对土壤的黏粒矿物组成差异及养分的影响;通过在东北黑土定点和历时8年的现代农业开垦利用,以研究东北黑土的黏粒矿物组成差异及养分的影响;经过8年的农业开垦利用后,东北黑土的风化进程加强,0.002~0.02 mm粉粒含量显著降低(F=5.84>P001=0.026),而黏粒含量因水土流失,增加未达到显著;土壤交换性离子活性较强,酸化程度加重,有机质含量降低,对养分保蓄能力明显下降.土壤中的伊利石含量极显著降低(F=11.25>P001=0.003),而高岭石和蒙脱石含量极显著增加(F=11.67>P001=0.003;F=13.89>P001=0.001),S/I混层矿物含量也较8年前的高;土壤黏粒矿物是极为敏感的胶体类型,它的改变会影响土壤肥力特征.%In order to identify the effect of agricultural use on clay minerals and nutrient of soil, th study of modern agriculture use of black soil in Northeast China has lasted for 8 years. Clay mineral com position and nutrient of black soil were investigated. The results showed that the weathering process of th black soil was strengthened. The content of silt fraction between 0.002 and 0.02mm was significantly de creased, while the content of clay fraction increase was not significant for soil erosion. Soil exchangeabl ion activity was strong, degree of acidification was increased, organic matter content decreased, and th nutrient holding capability decreased. The content of illite in soil was significantly lower, while the con tent of kaolinite and montmorillonite were significantly increased. The content of S / I mixed-layer miner al is higher than before 8 years. Soil clay minerals were a very sensitive type colloid, and its changes af fected soil fertility characteristics.

  19. 低分子量有机酸对粘土矿物吸附二氯喹啉酸的影响%Effect of low-molecular-weight organic acids on adsorption of quinclorac by clay minerals

    Institute of Scientific and Technical Information of China (English)

    杨丽华; 龚道新; 袁雅洁; 肖浩; 周健; 孟磊; 陈宣宇; 丁春霞

    2013-01-01

    采用批量平衡法,研究了6种低分子量有机酸(柠檬酸、酒石酸、苹果酸、乙酸、草酸和丁二酸)对3种粘土矿物(高岭土、蒙脱石、凹凸棒石)吸附二氯喹啉酸的影响.结果表明:当低分子量有机酸存在时,供试3种粘土矿物对二氯喹啉酸的吸附过程可用Linear和Freundlich吸附等温方程描述,且Freundlich方程的拟合效果更好.供试6种有机酸对二氯喹啉酸在高岭土中吸附量的影响程度从低到高依次为苹果酸<柠檬酸<草酸<乙酸<酒石酸<丁二酸,在蒙脱石中的顺序为乙酸<草酸<苹果酸<丁二酸<酒石酸<柠檬酸,在凹凸棒石中的顺序为乙酸<丁二酸<草酸<苹果酸<酒石酸<柠檬酸.不同浓度低分子量有机酸对3种供试粘土矿物吸附二氯喹啉酸均能产生显著的影响,但影响程度因粘土矿物和有机酸种类的不同而有较大差异.%The effect of low-molecular-weight organic acids (citric acid,tartaric acid,malic acid,acetic acid,oxalic acid and succinic acid) on adsorption of quinclorac by three clay minerals (kaolinite,montmorillonite and attapulgite) was investigated by a batch experimental technique.The results showed that the adsorption isotherm of quinclorac in clay minerals could be well described by Freundlich and Linear equation under the presence of low-molecular-weight organic acids,but the Freundlich equation was more suitable.The tested six kinds of low-molecular-weight organic acid showed different effects on adsorption quantity of quinclorac on kaolinite.The order from low to high influence were:malic acid < citric acid < oxalic acid < acetic acid < tartaric acid < succinic acid; whereas on montmorillonite from low to high order were:acetic acid < oxalic acid < malic acid < succinic acid <tartaric acid < citric acid; on attapulgite:acetic acid < succinic acid < oxalic acid < malic acid < tartaric acid < citric acid.In conclusion

  20. Clay mineral provinces in tidal mud flats at Germany's North Sea coast with illite K-Ar ages potentially modified by biodegradation

    Science.gov (United States)

    Brockamp, Olaf; Clauer, Norbert

    2012-07-01

    Mineralogical studies, chemical analyses and K-Ar dating were carried out on clay fractions from tidal mud flats along the Lower Saxony coast and its bays to identify material sources and sedimentary processes at this dynamic interface between air, land and sea. From the coast into the bays, sediments are enriched in fine-grained smectite relative to the coarser grained illite, chlorite and kaolinite, due to the weakening of the tidal current energy in the bays. In addition, the study area can be divided into two provinces on the basis of the illite K/Rb ratios and Mg contents. To the west [Schiermonnikoog, Dollart, Ley Bay up to Norderney island], longshore currents carry suspensions from the Belgian and Dutch coasts; to the east [from Langeoog island, Jade Bay to the Helgoland mud area] suspensions from the Elbe and Weser rivers are mixed with submarine reworked glacial sediments, whereas the portion of longshore current suspensions from the west decreases, becoming negligible in the Helgoland mud area off the Elbe and Weser estuaries. The illite K-Ar data vary considerably and fail as source indicators due to differential settling and mixing of the clay material and probably to Ar loss from illite by biodegradation during digestive processes. Only further offshore, outside the zone of dynamic sediment dispersion, do the K-Ar data fit provenance patterns.

  1. Thermostability of montmorillonitic clays

    Directory of Open Access Journals (Sweden)

    Petr Jelínek

    2014-05-01

    Full Text Available Bentonite is one of the most widespread used clays connected with various applications. In the case of foundry technology, bentonite is primarily used as a binder for mold manufacture. Thermal stability of bentonites is a natural property of clay minerals and it depends on the genesis, source and chemical composition of the clay. This property is also closely connected to bentonite structure. According to DTA analysis if only one peak of dehydroxylation is observed (about 600 ºC, the cis- isomerism of bentonite is expected, while two peaks of de-hydroxylation (about 550 and 850 ºC are expected in the trans- one. In this overview, the bentonite structure, the water – bentonite interaction and the swelling behavior of bentonite in connection with the general technological properties of bentonite molding mixture are summarized. Further, various types of methods for determination of bentonite thermostability are discussed, including instrumental analytical methods as well as methods that employ evaluation of various technological properties of bentonite binders and/or bentonite molding mixtures.

  2. Thermostability of montmorillonitic clays

    Institute of Scientific and Technical Information of China (English)

    Petr Jelnek; Stanisaw M.Dobosz; Jaroslav Beo; Katarzyna Major-Gabry

    2014-01-01

    Bentonite is one of the most widespread used clays connected with various applications. In the case of foundry technology, bentonite is primarily used as a binder for mold manufacture. Thermal stability of bentonites is a natural property of clay minerals and it depends on the genesis, source and chemical composition of the clay. This property is also closely connected to bentonite structure. According to DTA analysis if only one peak of dehydroxylation is observed (about 600 ºC), thecis- isomerism of bentonite is expected, while two peaks of de-hydroxylation (about 550 and 850 ºC) are expected in thetrans- one. In this overview, the bentonite structure, the water - bentonite interaction and the sweling behavior of bentonite in connection with the general technological properties of bentonite molding mixture are summarized. Further, various types of methods for determination of bentonite thermostability are discussed, including instrumental analytical methods as wel as methods that employ evaluation of various technological properties of bentonite binders and/or bentonite molding mixtures.

  3. Effects of clay minerals and organic matter in formulated sediments on the bioavailability of sediment-associated uranium to the freshwater midge, Chironomus dilutus

    Energy Technology Data Exchange (ETDEWEB)

    Crawford, Sarah E., E-mail: sarah.crawford@usask.ca [Toxicology Centre, University of Saskatchewan, 44 Campus Drive, Saskatoon, SK S7N 5B3 (Canada); Liber, Karsten, E-mail: karsten.liber@usask.ca [Toxicology Centre, University of Saskatchewan, 44 Campus Drive, Saskatoon, SK S7N 5B3 (Canada); School of Environment and Sustainability, 117 Science Place, University of Saskatchewan, Saskatoon, SK S7N 5C8 (Canada); Institute of Loess Plateau, 92 Wucheng Road, Shanxi University, Taiyuan, Shanxi 030006 (China)

    2015-11-01

    It is well established that bioavailability influences metal toxicity in aquatic ecosystems. However, the factors and mechanisms that influence uranium (U) bioavailability and toxicity in sediment have not been thoroughly evaluated, despite evidence that suggests different sediment components can influence the sorption and interaction of some metals. Given that dissolved U is generally accepted as being the primary bioavailable fraction of U, it is hypothesized that adsorption and interaction of U with different sediment components will influence the bioavailability of U in sediment. We investigated the effects of key sediment physicochemical properties on the bioavailability of U to a model freshwater benthic invertebrate, Chironomus dilutus. Several 10-day spiked sediment bioaccumulation experiments were performed, exposing C. dilutus larvae to a variety of formulated sediments spiked with different concentrations of U (5, 50 and/or 200 mg U/kg d.w.). Mean accumulation of U in C. dilutus larvae decreased significantly from 1195 to 10 mg U/kg d.w. as kaolin clay content increased from 0% to 60% in sediment spiked with 50 mg U/kg d.w. Similarly, higher organic matter content also resulted in a significant reduction of U bioaccumulation in C. dilutus larvae, indicating a reduction in U bioavailability. Concentrations of U in both the overlying water and sediment pore water displayed a strong positive relationship to U bioaccumulation in C. dilutus larvae (r{sup 2} = 0.77, p < 0.001 and r{sup 2} = 0.57, p < 0.001, respectively) for all experiments, while total U concentrations in the sediment had a poor relationship to U bioaccumulation (r{sup 2} = 0.10, p = 0.028). Results from this research confirm that sediment clay and organic matter content play a significant role in altering U bioavailability, which is important in informing risk assessments of U contaminated sites and in the development of site-specific sediment quality guidelines for U. - Highlights: • We

  4. Effects of clay minerals and organic matter in formulated sediments on the bioavailability of sediment-associated uranium to the freshwater midge, Chironomus dilutus.

    Science.gov (United States)

    Crawford, Sarah E; Liber, Karsten

    2015-11-01

    It is well established that bioavailability influences metal toxicity in aquatic ecosystems. However, the factors and mechanisms that influence uranium (U) bioavailability and toxicity in sediment have not been thoroughly evaluated, despite evidence that suggests different sediment components can influence the sorption and interaction of some metals. Given that dissolved U is generally accepted as being the primary bioavailable fraction of U, it is hypothesized that adsorption and interaction of U with different sediment components will influence the bioavailability of U in sediment. We investigated the effects of key sediment physicochemical properties on the bioavailability of U to a model freshwater benthic invertebrate, Chironomus dilutus. Several 10-day spiked sediment bioaccumulation experiments were performed, exposing C. dilutus larvae to a variety of formulated sediments spiked with different concentrations of U (5, 50 and/or 200 mg U/kg d.w.). Mean accumulation of U in C. dilutus larvae decreased significantly from 1195 to 10 mg U/kg d.w. as kaolin clay content increased from 0% to 60% in sediment spiked with 50 mg U/kg d.w. Similarly, higher organic matter content also resulted in a significant reduction of U bioaccumulation in C. dilutus larvae, indicating a reduction in U bioavailability. Concentrations of U in both the overlying water and sediment pore water displayed a strong positive relationship to U bioaccumulation in C. dilutus larvae (r(2) = 0.77, p<0.001 and r(2) = 0.57, p < 0.001, respectively) for all experiments, while total U concentrations in the sediment had a poor relationship to U bioaccumulation (r(2) = 0.10, p = 0.028). Results from this research confirm that sediment clay and organic matter content play a significant role in altering U bioavailability, which is important in informing risk assessments of U contaminated sites and in the development of site-specific sediment quality guidelines for U.

  5. Mars, clays and the origins of life

    Science.gov (United States)

    Hartman, Hyman

    1989-01-01

    To detect life in the Martian soil, tests were designed to look for respiration and photosynthesis. Both tests (labeled release, LR, and pyrolytic release, PR) for life in the Martian soils were positive. However, when the measurement for organic molecules in the soil of Mars was made, none were found. The interpretation given is that the inorganic constituents of the soil of Mars were responsible for these observations. The inorganic analysis of the soil was best fitted by a mixture of minerals: 60 to 80 percent clay, iron oxide, quartz, and soluble salts such as halite (NaCl). The minerals most successful in simulating the PR and LR experiments are iron-rich clays. There is a theory that considers clays as the first organisms capable of replication, mutation, and catalysis, and hence of evolving. Clays are formed when liquid water causes the weathering of rocks. The distribution of ions such as aluminum, magnesium, and iron play the role of bases in the DNA. The information was stored in the distribution of ions in the octahedral and tetrahedral molecules, but that they could, like RNA and DNA, replicate. When the clays replicated, each sheet of clay would be a template for a new sheet. The ion substitutions in one clay sheet would give rise to a complementary or similar pattern on the clay synthesized on its surface. It was theorized that it was on the surface of replicating iron-rich clays that carbon dioxide would be fixed in the light into organic acids such as formic or oxalic acid. If Mars had liquid water during a warm period in its past, clay formation would have been abundant. These clays would have replicated and evolved until the liquid water was removed due to cooling of Mars. It is entirely possible that the Viking mission detected life on Mars, but it was clay life that awaits the return of water to continue its evolution into life based on organic molecules.

  6. Mineralogy and geotechnical characteristics of some pottery clay

    Directory of Open Access Journals (Sweden)

    Mujib Olamide ADEAGBO

    2016-12-01

    Full Text Available The physical properties of soils, which are tremendously influenced by the active clay minerals in soil, are of great importance in geotechnical engineering. This paper investigates the clay-sized particles of the Igbara-Odo pottery clay, and compares results obtained with available data on the bulk sample, to determine their correlation and underline the dependence of the geotechnical properties of the bulk clay material on the clay-sized particles. The bulk clay sample consists of 52% sand-size particles, 21% silt and 27% clay. Analysis of the clay-sized particles and the bulk materials shows: specific gravity of 2.07 and 2.66, liquid limit of 91.0% and 33.0%, plastic limit of 27.5% and 14.3%, plasticity index of 63.5% and 18.7% and a linear shrinkage of 7.9% and 5.4%, for both clay-sized particles and bulk clay respectively. The activity value of the clay material (0.64 suggests the presence of Kaolinite and Ilite; and these were confirmed with X-Ray diffraction on the bulk sample and clay-sized particles. X-Ray diffraction patterns shows distinctive peaks which highlight the dominance of Kaolinite (with 8 peaks in the pottery clay sample for both clay-sized particles and bulk material; while traces of other clay minerals like Illite and Halloysite and rock minerals like Mica, Feldspar and Chrysotile were also found. These results suggest that the clay possesses high viability in the manufacturing of ceramics, refractory bricks, paper, fertilizer and paint. The clay material can be used as a subgrade in road construction, since it possesses low swelling characteristics.

  7. Genotoxic potential of montmorillonite clay mineral and alteration in the expression of genes involved in toxicity mechanisms in the human hepatoma cell line HepG2.

    Science.gov (United States)

    Maisanaba, Sara; Hercog, Klara; Filipic, Metka; Jos, Ángeles; Zegura, Bojana

    2016-03-01

    Montmorillonite, also known as Cloisite(®)Na(+) (CNa(+)), is a natural clay with a wide range of well-documented and novel applications, such as pharmaceutical products or food packaging. Although considered a low toxic product, the expected increased exposure to CNa(+) arises concern on the potential consequences on human and environmental health especially as its genotoxicity has scarcely been investigated so far. Thus, we investigated, for the first time, the influence of non-cytotoxic concentrations of CNa(+) (15.65, 31.25 and 62.5 μg/mL) on genomic instability of human hepatoma cell line (HepG2) by determining the formation of micronuclei (MNi), nucleoplasmic bridges (NPBs) and nuclear buds (NBUDs) with the Cytokinesis block micronucleus cytome assay. Further on we studied the influence of CNa(+) on the expression of several genes involved in toxicity mechanisms using the real-time quantitative PCR. The results showed that CNa(+) increased the number of MNi, while the numbers of NBUDs and NPBs were not affected. In addition it deregulated genes in all the groups studied, mainly after longer time of exposure. These findings provide the evidence that CNa(+) is potentially genotoxic. Therefore further studies that will elucidate the molecular mechanisms involved in toxic activity of CNa(+) are needed for hazard identification and human safety assessment.

  8. A new microenvironment for the formation of clay minerals: the example of authigenic halloysite-7Å and gibbsite in a stalactite from Agios Georgios Cave, Kilkis, north Greece

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    Elena Ifandi, University of Patras

    2015-09-01

    Full Text Available An unusual authigenic origin for halloysite and gibbsite is reported in a stalactite from Agios Georgios Cave, Kilkis. This speleothem includes mostly pure calcite whereas minor areas of Mg-rich calcite and scarce dolomite are present in four growth phases. Abundant pores are created due to imperfect coalescence of the calcite crystals. Several of them contain detrital muscovite, which was presumably transferred from the dripping water, during the formation of speleothem and has been variably altered to halloysite. Several pores in the stalactite contain different mineral assemblages that we interpret as in situ: halloysite-7Å, halloysite + silica, gibbsite + silica and gibbsite. The breakdown of the muscovite and the formation of halloysite require acidic conditions, which we suggest to have been established by potassium solubilising microorganisms. The silica minerals include spheroidal assemblages or needle-like and blade-like quartz and can be explained by further dissolution of halloysite, under the same acidic conditions in the presence of microorganisms. In our model, the precipitation of gibbsite is the result of direct formation from muscovite, promoted from abundant and undisturbed water percolation, at moderately low pH, also induced by the presence of bacteria. Given that microbial activities promote: (1 breakdown of muscovite and formation of halloysite, silica, and gibbsite, and (2 formation of Mg-calcite and dolomite after calcite, then it is likely that two or more different microbial communities may exist in the same speleothem. The first creates mild acidic conditions, aiming at the decomposition of muscovite in the microenvironment of the pores antagonising the second that produces alkaline microregimes and the local precipitation of Mg-rich carbonate minerals.

  9. REE and (э)Nd of clay fractions in sediments from the eastern Pacific Ocean: Evidence for clay sources

    Institute of Scientific and Technical Information of China (English)

    LIU Jihua; SHI Xuefa; CHEN Lirong; HUANG Yongyang; WANG Yinxi; CUI Yingchun; BU Wenrui

    2005-01-01

    Clay fractions in the non-calcareous surface sediments from the eastern Pacific were analyzed for clay minerals, REE and 143Nd/144Nd. Montmorillonite/illite ratio (M/I ratio), total REE contents ((REE), LREE/HREE ratio and cerium anomaly (бCe) may effectively indicate the genesis of clay minerals. Clay fractions with M/I ratio >1, бCe (0.85, (REE (400 μg/g, LREE/HREE ratio (4, and REE patterns similar to those of pelagic sediments are terrigenous and autogenetic mixed clay fractions and contain more autogenetic montmorillonite. Clay fractions with M/I ratio <1, бCe=0.86 to 1.5, ΣREE=200 to 350 μg/g, LREE/HREE ratio (6 and REE distribution patterns similar to that of China loess are identified as terrigenous clay fraction. The 143Nd/144Nd ratios or (э)Nd values of clay fractions inherit the features of terrigenous sources of clay minerals. Clay fractions are divided into 4 types according to (э)Nd values. Terrigenous clay minerals of type I with the (э)Nd values of -8 to -6 originate mainly from North American fluvial deposits. Those of type II with the (э)Nd values of -9 to -7 are mainly from the East Asia and North American fluvial deposits. Those of type III with (э)Nd values of -6 to -3 could come from the central and eastern Pacific volcanic islands. Those of type IV with (э)Nd values of -13 to -12 may be from East Asia eolian. The terrigenous and autogenetic mixed clay fractions show patchy distributions, indicating that there are volcanic or hot-spot activities in the eastern Pacific plate, while the terrigenous clay fractions cover a large part of the study area, proving that the terrigenous clay minerals are dominant in the eastern Pacific.

  10. CLAY AND CLAY-SUPPORTED REAGENTS IN ORGANIC SYNTHESES

    Science.gov (United States)

    CLAY AND CLAY-SUPPORTED REAGENTS HAVE BEEN USED EXTENSIVELY FOR SYNTHETIC ORGANIC TRANSFORMATIONS. THIS OVERVIEW DESCRIBES THE SALIENT STRUCTURAL PROPERTIES OF VARIOUS CLAY MATERIALS AND EXTENDS THE DISCUSSION TO PILLARED CLAYS AND REAGENTS SUPPORTED ON CLAY MATERIALS. A VARIET...

  11. Common clay and shale

    Science.gov (United States)

    Virta, R.L.

    2011-01-01

    The article discusses the latest developments in the global common clay and shale industry, particularly in the U.S. It claims that common clay and shale is mainly used in the manufacture of heavy clay products like brick, flue tile and sewer pipe. The main producing states in the U.S. include North Carolina, New York and Oklahoma. Among the firms that manufacture clay and shale-based products are Mid America Brick & Structural Clay Products LLC and Boral USA.

  12. [Comparison of FRAX Score without bone mineral density determination and the criteria proposed by the Argentine Osteoporosis Society for the use of antiresorptive therapy in postmenopausal women].

    Science.gov (United States)

    Camporro, Fernando; Redondo, Laura; Bulacio, Exequiel; Gutiérrez Magaldi, Ignacio; Chamale, Elías; Sáenz, Fabián

    2015-01-01

    To identify patients at high risk of fracture using clinical risk factors could reduce health costs arising from the realization of a bone densitometry. The aim of this study was to compare the FRAX score without bone mineral density (BMD) with the criteria proposed by the Argentine Society of Osteoporosis (SAO) to consider starting antiresorptive treatment. We conducted an observational, cross-sectional study where 330 postmenopausal women between 40 and 90 years of age were included. The number of treatments given if the FRAX tool without BMD had been followed was compared with the number of treatments indicated using the SAO criteria. Using the SAO criteria, 85 (25.8%) patients would initiate antiresorptive treatment compared with 15 (4.5%) using the FRAX without BMD (p = 0.0019). Among the 67 patients with a diagnosis of osteoporosis by BMD determination, all of them (100%) would have received treatment by using the SAO criteria compared with 10 (15%) using the FRAX score (p = 0.011). The use of FRAX without BMD significantly underestimates the number of patients who should receive antiresorptive treatment. In patients diagnosed with osteoporosis by BMD, the FRAX score underestimates the number of patients to be treated.

  13. Influence of Storage Conditions on Geotechnical Properties of Ariake Clay and on its Chemical Stabilization

    OpenAIRE

    シナ, コスラナント; SINAT, KOSLANANT

    2006-01-01

    Influence of storage conditions on geotechnical properties of Ariake clay and on its chemical stabilization is investigated to make use of the surplus clay as construction materials. The influence factors in lime and cement stabilization including salts, diatom and clay minerals were studied. The experiments were set up by mixing clays with various proportions of studied factors. As a result, for Bangkok clay, Kaolin and Bentonite, the factors improving the unconfined compressive strength of...

  14. Modified clay sorbents

    Energy Technology Data Exchange (ETDEWEB)

    Fogler, H.S.; Srinivasan, K.R.

    1990-04-10

    This patent describes a clay-based sorbent. It comprises a clay having an external surface and lamellar layers; and cationic surfactant ions having a hydrocarbon portion and a cationic head portion, the cationic surfactant ions being irreversibly bound to the external surface by the hydrocarbon portion. This patent also describes cetylpyridinium-aluminum hydroxy-montmorillonite; the clay-based sorbent wherein the clay is a non-expandable clay; and the clay-based sorbent wherein the cationic surfactant ions are selected from the group consisting of ionized cetylpyridinium chloride and cetylakonium chloride.

  15. Porosity Investigation of Kosova's Clay

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    Makfire Sadiku

    2011-01-01

    Full Text Available Problem statement: Acid activated clay minerals are used as catalysts in the desulphurization of crude oil or as catalyst carrier, as drilling mud, as bleaching earth. Approach: The efficiency of the acid activation can be described in two ways. As increase of the surface and as increase of the cumulative pore volume after the activation. Results: In different samples of the clay mineral the activation was done with different sulfuric acid concentrations for two and 3h. Afterwards the specific surface was measured by means of nitrogen adsorption. All the measured isotherms belong to the pseudo-two kind. After the activation the surface enhanced from around 100-180 m2 g-1. The mesopore distribution is calculated out of the hysteresis between adsorption-desorption isotherms of the nitrogen. Conclusion: It is shown that the activation increases significantly the amount of mesopores which is reflected in the cumulative volume. The macrospore volume of the clay samples were measured by means of mercury intrusion porosimetry for pore sizes up to 320 nm. The volume of the macrospores results to an increase up to two times after the activation. The cumulative volume of all the pores is shown like a good parameter of the efficiency of the acid activation. The measurements were fulfilled in the newly equipped laboratory of the surface characterizations of the Tirana University. These analyses are of big interest for the industry in Albania and Kosove.

  16. Toward Accurate Adsorption Energetics on Clay Surfaces

    CERN Document Server

    Zen, Andrea; Cox, Stephen J; Hu, Xiao L; Sorella, Sandro; Alfè, Dario; Michaelides, Angelos

    2016-01-01

    Clay minerals are ubiquitous in nature, and the manner in which they interact with their surroundings has important industrial and environmental implications. Consequently, a molecular-level understanding of the adsorption of molecules on clay surfaces is crucial. In this regard computer simulations play an important role, yet the accuracy of widely used empirical force fields (FF) and density functional theory (DFT) exchange-correlation functionals is often unclear in adsorption systems dominated by weak interactions. Herein we present results from quantum Monte Carlo (QMC) for water and methanol adsorption on the prototypical clay kaolinite. To the best of our knowledge, this is the first time QMC has been used to investigate adsorption at a complex, natural surface such as a clay. As well as being valuable in their own right, the QMC benchmarks obtained provide reference data against which the performance of cheaper DFT methods can be tested. Indeed using various DFT exchange-correlation functionals yields...

  17. ADSORPTION OF BACTERIOPHAGES ON CLAY MINERALS

    Science.gov (United States)

    Theability to predict the fate of microorganisms in soil is dependent on an understanding of the process of their sorption on soil and subsurface materials. Presently, we have focused on studying the thermodynamics of sorption of bacteriophages (T-2, MS-2, and

  18. Discontinuity networks in mud stones: an apparent contradiction for boom clay at Mol, opalinus clay at Mont Terri, Callovo-Oxfordian silty clay at Bure

    Energy Technology Data Exchange (ETDEWEB)

    Arnould, M. [Centre de Geologie de l' Ingenieur, 75 - Paris (France); Mazurek, M. [Bern Univ., Rock-Water Interaction, Institute of Geological Sciences (Switzerland); Vandenberghe, N. [Katholieke Universiteit (KU), Lab. voor stratigrafie Leuven (Belgium)

    2005-07-01

    The Rupelian Boom Clay at Mol, Belgium, the lower Aalenian Opalinus Clay at Mont Terri Switzerland and the Callovo-Oxfordian silty clay at Bure, France, are currently studied in the framework of deep geological radioactive waste confinement. These three mud-stones are calcareous to variable degrees. They vary from plastic clay at Mol to hard rock at Bure. All three have similar mineralogical constituents, especially with regards to the clay minerals and include mixed layers of illite and montmorillonite. Remarkably, in outcrop sections of massive clay formations and mud-stone in general, it is very common to observe a network of discontinuities resembling the jointing in hard rock. As such jointing clearly would influence underground works it is imperative to examine whether or not the three mud-rock formations under discussion have such a discontinuity network in all their mass. (authors)

  19. The influence of clay type on reduction of water repellency by applied clays: a review of some West Australian work

    Science.gov (United States)

    McKissock, I.; Walker, E. L.; Gilkes, R. J.; Carter, D. J.

    2000-05-01

    In Western Australia water repellency mostly occurs in soils with sandy texture; the severity of water repellency is influenced by very small changes in clay content. Additions of 1-2% clay can prevent water repellency and for some time clay amendments have been used by farmers to overcome water repellency. The aim of this study was to assess the effectiveness of clays in ameliorating water repellency. Clays were assessed for effectiveness in reducing water repellency by mixing with water repellent sands and measuring water drop penetration time (WDPT) on the resultant mixtures. WDPT was measured on the initial mixtures, a wetting and drying cycle was imposed and WDPT measured again. Two sets of clays were assessed: four simple clays containing kaolinite (2) or smectite (2) group minerals and a group of clayey subsoil materials which had been collected by farmers. For the simple clays, clay mineral type was the most significant factor in determining response. Kaolin was much more effective than smectite. Imposition of a wetting and drying cycle greatly reduced water repellency. The dominant exchangeable cation of the clays (sodium or calcium) had little effect on the ability of the clays to reduce water repellency. The factor that was most predictive of the effectiveness of clayey subsoils materials in reducing water repellency was texture: clay content ( r2=0.18) or clay+silt content ( r2=0.23). These properties were more predictive of water repellency values after the wetting and drying cycle treatment ( r2=0.36, r2=0.44). The proportion of the clay fraction that consisted of kaolinite was next most predictive in determining effectiveness which is again indicative of kaolin group minerals being more effective than smectite group minerals. The exchangeable sodium percentage and clay dispersibility had no systematic effect on the ability of these clays to reduce water repellency. These results provide a basis for developing a practical field procedure to enable

  20. Importância das espécies minerais no potássio total da fração argila de solos do Triângulo Mineiro Importance of mineral species in total potassium content of clay fraction in soils of the Triângulo Mineiro, Minas Gerais State, Brazil

    Directory of Open Access Journals (Sweden)

    V. F. Melo

    2003-10-01

    arenito da Formação Uberaba, migmatito/micaxisto do Grupo Araxá e basalto da Formação Serra Geral.Few studies relate the K reserve in soils developed in a humid tropic climate with the minerals found in the clay fraction. Nineteen soils were collected for this purpose in the Triângulo Mineiro region, Minas Gerais State, Brazil, developed from different parent materials and different weathering degrees. Due to the greater occurrence, a larger number of samples of the Bauru Group was collected, comprising all the geological formations found in the region. The total K content in soil and the sand, silt, and clay fractions were determined after the digestion of the soil samples by HF, HNO3 and H2SO4. To quantify the contribution of each mineral species to the total K content, Na-saturated clay samples were submitted by a sequential and selective mineral extraction procedure, following the order: amorphous Al and Fe oxides; crystalline Fe oxides; kaolinite and gibbsite; mica and other 2:1 minerals and; feldspar and resistant minerals. The clay mineralogy composition reflects the high weathering and leaching degree in soils of the Triângulo Mineiro, with low contents of amorphous minerals, a predominant proportion of kaolinite and the presence of other secondary resistant minerals. In spite of this mineral composition, the clay fraction presented the highest total K content, mainly in the most weathered soils. Due to the high proportion of kaolinite in the clay fraction, this mineral was an important source of non-exchangeable K forms. On the other hand, the contribution of amorphous Fe and Al oxides and crystalline Fe oxides to the total K content of the clay fraction was negligible. In general, easily weathered primary minerals (mica and feldspar contributed largely to the total K of the clay fraction, principally to the youngest soils developed from the Uberaba (sandstone and Serra Geral (basalt Formations, and the Araxá Group (migmatite/micaschist.

  1. Transformações mineralógicas e cristaloquímicas decorrentes dos ensaios termais em argilas cauliníticas ferruginosas Mineralogical and crystalochemical transformations originated from thermal essays on ferruginous kaolinitic clays

    Directory of Open Access Journals (Sweden)

    M. M. Ferreira

    2012-03-01

    Full Text Available Transformações mineralógicas e cristaloquímicas foram investigadas em amostras de argilas cauliníticas ferruginosas aquecidas a temperaturas de 800, 1000 e 1200 °C. As análises de difração de raios X e térmica diferencial e gravimétrica mostraram ser a caulinita o argilomineral predominante nas amostras naturais. Os resultados da espectroscopia Mössbauer mostraram que o alto conteúdo em Fe (22,5% em peso, determinado por fluorescência de raios X, é relacionado à presença de goethita (18% em peso e hematita (16% em peso. Entretanto um resíduo deste elemento (Fe3+ e Fe2+ foi constatado após a extração do ferro usando solução de ditionito-citrato-bicarbonato, e possivelmente se deve à presença de ferro na estrutura da caulinita. O processo de sinterização mostra uma desestruturação da caulinita, assim como a transformação da goethita em hematita, cujo tamanho dos cristais cresce com o incremento da temperatura. O tamanho do cristal de hematita a 1200 °C é 5 vezes maior do que na amostra natural. A mulita formada a 1000 °C é constituída da solução sólida de Fe2O3, com Al2O3, o que resulta em produto resistente e de maior estabilidade térmica.Mineralogical and crystallochemical transformations of representative ferruginous kaolinitic clay samples were investigated in specimens burned at 800, 1000 and 1200 °C. X-ray diffraction and differential thermal and thermogravimetric analyses showed that kaolinite was the predominant mineral in the raw samples. The Mössbauer spectroscopy results showed that the high iron content (22.5 wt.%, as determined by X-ray fluorescence, is related to the presence of goethite (18 wt.% and hematite (16 wt.%. However, after Fe was extracted using a dithionite-citrate system buffered with sodium bicarbonate, a residue of this element (Fe3+ and Fe2+ was found in the structure of the kaolinite. The sintering process showed the destruction of kaolinite, as well as the transformation of

  2. Soil clay content underlies prion infection odds

    Science.gov (United States)

    David, Walter W.; Walsh, D.P.; Farnsworth, Matthew L.; Winkelman, D.L.; Miller, M.W.

    2011-01-01

    Environmental factors-especially soil properties-have been suggested as potentially important in the transmission of infectious prion diseases. Because binding to montmorillonite (an aluminosilicate clay mineral) or clay-enriched soils had been shown to enhance experimental prion transmissibility, we hypothesized that prion transmission among mule deer might also be enhanced in ranges with relatively high soil clay content. In this study, we report apparent influences of soil clay content on the odds of prion infection in free-ranging deer. Analysis of data from prion-infected deer herds in northern Colorado, USA, revealed that a 1% increase in the clay-sized particle content in soils within the approximate home range of an individual deer increased its odds of infection by up to 8.9%. Our findings suggest that soil clay content and related environmental properties deserve greater attention in assessing risks of prion disease outbreaks and prospects for their control in both natural and production settings. ?? 2011 Macmillan Publishers Limited. All rights reserved.

  3. Reply to Comment by Xu et al. on "Sr-Nd isotope composition and clay mineral assemblages in eolian dust from the central Philippine Sea over the last 600 kyr: Implications for the transport mechanism of Asian dust" by Seo et al.

    Science.gov (United States)

    Seo, Inah; Lee, Yong Il; Yoo, Chan Min; Kim, Hyung Jeek; Hyeong, Kiseong

    2016-12-01

    Against Xu et al. (2016), who argued that East Asian Desert (EAD) dust that traveled on East Asian Winter Monsoon winds dominates over Central Asian Desert (CAD) dust in the Philippine Sea with presentation of additional data, we reconfirm Seo et al.'s (2014) conclusion that CAD dust carried on the Prevailing Westerlies and Trade Winds dominates over EAD dust in overall dust budget of the central Philippine Sea. The relative contribution of dust from EADs and CADs using clay mineral composition should be evaluated with elimination of mineralogical contribution from the volcanic end-member which is enriched in kaolinite and overestimate the contribution of EAD dust.

  4. Role of clay as catalyst in Friedel–Craft alkylation

    Indian Academy of Sciences (India)

    Tanushree Choudhury; Nirendra M Misra

    2011-10-01

    Solid acids have become increasingly important for many liquid-phase industrial reactions these days. Montmorillonite clays (2:1 clay mineral) have been used as efficient solid acid catalysts for a number of organic and liquid phase reactions and offer several advantages over classic acids. Tailor made catalysts can be prepared from clays by suitably adjusting their acidity and surface area by acid activation. In the present work, preparation, characterization and performance of Pt (II) clays, Cu (II) clays, acid clay, and sol–gel hybrids of Cu (II) clays as solid catalysts in a test Friedel–Craft alkylation reaction of benzyl chloride with toluene using differential scanning calorimeter (DSC) are reported. Product formation has been analysed by FTIR spectroscopy. The main objective of this work is to show how clay as a solid catalyst affects reaction rates and activation energies. Acidity and dispersion of solid catalysts are twomain factors which govern a catalysis reaction. Kinetic parameter analysis and XRD studies confirm that acid Pt (II) clay and Pt (II) clay dispersed by natural dispersants aremore effective catalysts. In contrast to the reactions using AlCl3, the experimental conditions are non-polluting and the final work up does not require any aqueous treatment.

  5. Clay Portrait Boxes

    Science.gov (United States)

    Wilbert, Nancy Corrigan

    2009-01-01

    In an attempt to incorporate sculptural elements into her ceramics program, the author decided to try direct plaster casting of the face to make a plaster mold for clay. In this article, the author shares an innovative ceramics lesson that teaches students in making plaster casts and casting the face in clay. This project gives students the…

  6. Columns in Clay

    Science.gov (United States)

    Leenhouts, Robin

    2010-01-01

    This article describes a clay project for students studying Greece and Rome. It provides a wonderful way to learn slab construction techniques by making small clay column capitols. With this lesson, students learn architectural vocabulary and history, understand the importance of classical architectural forms and their influence on today's…

  7. Siderophore sorption to clays.

    Science.gov (United States)

    Maurice, Patricia A; Haack, Elizabeth A; Mishra, Bhoopesh

    2009-08-01

    Siderophores are low molecular weight organic ligands exuded by some aerobic organisms and plants to acquire Fe under Fe-limited conditions. The hydroxamate siderophores may sorb to aluminosilicate clays through a variety of mechanisms depending upon the nature of the clay and of the siderophore along with solution conditions such as pH, ionic strength, and presence of metal cations. They may also affect metal binding to clays. Here, we review previous studies of siderophore sorption to aluminosilicate clays; briefly discuss how the techniques of X-ray diffractometry, Fourier-transform infrared spectroscopy, and X-ray absorption spectroscopy may be applied to such studies; review effects of siderophores on metal sorption to clays; and highlight some areas for future research.

  8. Characterization of some clay deposits in South West Nigeria

    Directory of Open Access Journals (Sweden)

    Fatai Olufemi ARAMIDE

    2014-11-01

    Full Text Available Clay minerals are the most important industrial minerals whose application is dependent on its structure and chemical composition. Mineralogical, chemical compositions, phase constitutions, and microstructural morphology of certain clay minerals from three different deposits in south western Nigeria were investigated using state-of-the-art equipment. These were done with the intention of determining the appropriate application for the clay minerals. It was observed that the major phases in the clay samples from the three different deposits are kaolinite, microcline, muscovite/illite, plagioclase/albite and quartz. These phases were observed in varied percentages. It was concluded that sample A (Ifon clay which contains very low kaolinite (5.63%; could not use for making high temperature caliber refractories. But due to its high content of feldspar, it could be processed for the production of feldspar for glass and iron making industries. Sample B is considered to be appropriate for the production the refractory composite due to its most appropriate content of both kaolinite (23.74% kaolinite and feldspars (26.12% microcline and 11.28% plagioclase/albite which is necessary for producing mullite fibers in ceramic matrix at a temperature of around 1400oC. Sample C (Iseyin clay, which contains very low feldspars (3.00% microcline and 3.08% plagioclase/albite and high content of kaolinite was considered suitable for further processing for making high temperature caliber refractories.

  9. Caracterização dos argilominerais usados em matéria-prima cerâmica, da formação Rio do Rasto, Bacia do Paraná, no município de Turvo, SC Characterization of clay minerals used in the ceramic industry, from Rio do Rasto formation, Paraná basin, exploitation in Turvo, SC, Brazil

    Directory of Open Access Journals (Sweden)

    J. A. Costa

    2010-12-01

    Full Text Available No sudeste de Santa Catarina existem inúmeras minas de exploração de argilas destinadas à indústria cerâmica da região. Para o conhecimento desta matéria prima foi realizada a caracterização em detalhe de uma frente de lavra em atividade. A exploração é realizada em terrenos sedimentares da Formação Rio do Rasto (Permiano Superior na Bacia do Paraná que afloram como morros testemunho. Foram coletadas quatorze amostras representativas dos níveis desta mina composta de argilitos com intercalação de siltitos de pequena espessura. As amostras foram analisadas por difratometria de raios X pelo método do pó na rocha total e na fração In the southeastern part of Santa Catarina state, Brazil, many mines of clays used as raw material for the ceramic industry are found. A detail study of this material was developed in a mine in activity. The exploitation of clays is held in sedimentary rocks of Rio do Rasto Formation (Upper Permian in the Paraná Basin. The outcrops are in hills testimonies. Fourteen samples were collected and represent the levels of this mine which consisted of argillites with intercalation of slim siltite layer. These samples were analyzed by X-ray diffraction using the powder method and in the fraction < 4 µm. The chemical composition was determined by X-ray fluorescence spectrometer. Petrographic observations in thin section were also performed. Scanning electron microscope images was obtained in samples fragments by secondary electron method. Electron microprobe microanalysis was performed in one thin section. The results showed large vertical variation in the mineralogy and it has been identified three different levels. Up to 2.00 m there is a predominance of smectite. Between 5.50 m 2.00 m the smectite is the main clay mineral, but with significant amounts of illite/mica and above 5.50 m occurs large increase in K-feldspar and detrital mica. Studies in detail by X-ray diffraction (determination of the b

  10. Levels of lead, arsenic, mercury and cadmium in clays for oral use on the Dutch market and estimation of associated risks

    NARCIS (Netherlands)

    Reeuwijk, N.M.; Klerx, W.N.M.; Kooijman, M.; Hoogenboom, L.A.P.; Rietjens, I.M.C.M.; Martena, M.J.

    2013-01-01

    Pregnant women in Africa, Asia and Suriname, and some immigrants in Western societies, traditionally consume clay products known by a variety of names such as mabele, calabash chalk, sikor and pimba. Furthermore, clay is used for health purposes in Western societies. Because certain clays can contai

  11. EFFECT OF CALCINATION TEMPERATURE OF TUNISIAN CLAYS ON THE PROPERTIES OF GEOPOLYMERS

    Directory of Open Access Journals (Sweden)

    Essaidi N.

    2013-09-01

    Full Text Available Geopolymers are amorphous three dimensional aluminosilicate materials that may be synthesized at room or slightly higher temperature by alkaline activation of aluminosilicates obtained from industrial wastes, calcined clays and natural minerals. Among the different family of geopolymers, two Tunisian clays (a kaolinite clay from Tabarka and illito/kaolinitic clay from Medenine are tested for their feasibility of geopolymers at low temperature. The unfired and calcined clays were dissolved in strongly alkaline solution in order to produce consolidated materials whose pastes were characterized by their compressive strength. Hardened geopolymer samples were also submitted to X-Ray diffraction, FTIR spectroscopy and scanning electron microscopy analyses. The geopolymer strength is related to the structure and reactivity of the clay generated by thermal treatment and to the role of associated minerals in clays. The amorphous character of obtained geopolymers and the displacement of the IR wavenumber are signature of geopolymerisation reaction.

  12. Characterization of clay from northern of Morocco for their industrial application

    Science.gov (United States)

    El Ouahabi, Meriam; Fagel, Nathalie

    2010-05-01

    Clays are a natural resource used for millennia. Currently applications such as industrial minerals are diversified. In this context, our goal is to estimate the potential of the many clay deposits in northern of Morocco. The choice of this region is justified by the particular abundance of clay deposits used to manufacture building materials (brick, ceramic and refractories) and pottery. This study focuses on the mineralogical, chemical and geotechnical characterization tests carried out on Tangier-Tetouan and Meknes clays from northern of Morocco. The suitability of raw clay material from those regions in order to produce ceramic and brick has not been tested yet. The results revealed that the studied samples are diversified, kaolinite and illite (Tetouan clay) and kaolinite and illite and smectite and vermiculite (Tangier and Meknes clay) based materials. There were no major differences in grain-size distribution, whereas Meknes clay was more plastic than Tetouan-Tangier clay. The cation exchange capacity show that Meknes and Tangier clay were more important than Tetouan clay. Specific surface area and thermal analaysis complete this caracterization. It was found that almost all technological properties of the Meknes clay deposit are led to the manufacture of ceramic floor tile, and Tetouan-Tangier clay provide opportunities to making brick and ceramic floor. The Tetouan-Tangier and Meknes clay are a potential ceramic raw material for growing Morrocan ceramic tile and brick industries.

  13. Clays as dietary supplements for swine: A review.

    Science.gov (United States)

    Subramaniam, Mohana Devi; Kim, In Ho

    2015-01-01

    Clays are crystalline, hydrated aluminosilicate molecules composed of alkali and alkaline earth cations along with small amounts of various other elements. The best-known are montmorillonite, smectite, illite, kaolinite, biotite and clinoptilolite. The molecules in these clays are arranged in three-dimensional structures creating internal voids and channels capable of trapping a wide variety of molecules. As a result of this structure, clay minerals are regarded as a simple and effective tool for the prevention of the negative effects of many toxic compounds. Dietary supplementation with clays has been shown to improve weight gain and feed conversion in pigs. Where improvements in performance have been noted, one of the most likely explanations for the improvement is the fact clays increase nutrient digestibility. Clays reduce the speed of passage of feed along the digestive tract which allows more time for digestion. Feeding clays also causes morphological changes in the intestinal mucosa such as an increase in villus height and an increase in the villus height to crypt depth ratio. These changes increase the surface area of the gastrointestinal tract thus increasing nutrient digestibility. Several studies have indicated that feeding clay reduces the incidence, severity and duration of diarrhea in pigs. The mechanism for the reduction in diarrhea is likely due to increases in the numbers of Bifidobacteria and Lactobacillus and decreases in Clostridia and E. coli in the small intestine of pigs fed clays. In addition, the numbers of pigs born alive and weaned, birth weight and weaning weight have been shown to be higher for sows fed clays. Several studies have indicated that clays can help mitigate the effects of mycotoxins. The aim of the present review is to focus on the various clays which have been given attention in recent research and to discuss their potential to improve pig performance.

  14. Clays in natural and engineered barriers for radioactive waste confinement

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-07-01

    Andra organised an International Symposium on the use of Natural and Engineered Clay-based Barriers for the Containment of Radioactive Waste hold at the Congress Centre of Tours, France, in March 2005. The symposium provided an opportunity to take stock of the potential properties of the clay-based materials present in engineered or natural barriers in order to meet the containment specifications of a deep geological repository for radioactive waste. It was intended for specialists working in the various disciplines involved with clays and clay based minerals, as well as scientists from agencies and organisations dealing with investigations on the disposal of high-level and long-lived radioactive waste. The themes of the Symposium included geology, geochemistry, transfers of materials, alteration processes, geomechanics, as well as the recent developments regarding the characterisation of clays, as well as experiments in surface and underground laboratories. The symposium consisted of plenary sessions, parallel specialized sessions and poster sessions. (author)

  15. Clay goes patchy

    NARCIS (Netherlands)

    Kegel, W.K.; Lekkerkerker, H.N.W.

    2011-01-01

    Empty liquids and equilibrium gels have so far been only theoretical possibilities, predicted for colloids with patchy interactions. But evidence of both has now been found in Laponite, a widely studied clay.

  16. Studies on the acid activation of Brazilian smectitic clays

    Directory of Open Access Journals (Sweden)

    Valenzuela Díaz Francisco R.

    2001-01-01

    Full Text Available Fuller's earth and acid activated smectitic clays are largely used as bleaching earth for the industrial processing of vegetable, animal and mineral oils and waxes. The paper comments about the nomenclature used for these materials, the nature of the acid activation of smectitic clays (bentonites, activation laboratory procedures and presents a review of the acid activation of bentonites from 20 deposits from several regions of Brazil. The activated clays were tested and show good decolorizing power for soybean, castor, cottonseed, corn and sunflower oils.

  17. Pathogenesis and diagnostic criteria for rickets and osteomalacia--proposal by an expert panel supported by the Ministry of Health, Labour and Welfare, Japan, the Japanese Society for Bone and Mineral Research, and the Japan Endocrine Society.

    Science.gov (United States)

    Fukumoto, Seiji; Ozono, Keiichi; Michigami, Toshimi; Minagawa, Masanori; Okazaki, Ryo; Sugimoto, Toshitsugu; Takeuchi, Yasuhiro; Matsumoto, Toshio

    2015-09-01

    Rickets and osteomalacia are diseases characterized by impaired mineralization of bone matrix. Recent investigations have revealed that the causes of rickets and osteomalacia are quite variable. Although these diseases can severely impair the quality of life of affected patients, rickets and osteomalacia can be completely cured or at least respond to treatment when properly diagnosed and treated according to the specific causes. On the other hand, there are no standard criteria to diagnose rickets or osteomalacia nationally and internationally. Therefore, we summarize the definition and pathogenesis of rickets and osteomalacia, and propose diagnostic criteria and a flowchart for the differential diagnosis of various causes of these diseases. We hope that these criteria and the flowchart are clinically useful for the proper diagnosis and management of these diseases.

  18. Pathogenesis and diagnostic criteria for rickets and osteomalacia - proposal by an expert panel supported by Ministry of Health, Labour and Welfare, Japan, The Japanese Society for Bone and Mineral Research and The Japan Endocrine Society.

    Science.gov (United States)

    Fukumoto, Seiji; Ozono, Keiichi; Michigami, Toshimi; Minagawa, Masanori; Okazaki, Ryo; Sugimoto, Toshitsugu; Takeuchi, Yasuhiro; Matsumoto, Toshio

    2015-01-01

    Rickets and osteomalacia are diseases characterized by impaired mineralization of bone matrix. Recent investigations revealed that the causes for rickets and osteomalacia are quite variable. While these diseases can severely impair the quality of life of the affected patients, rickets and osteomalacia can be completely cured or at least respond to treatment when properly diagnosed and treated according to the specific causes. On the other hand, there are no standard criteria to diagnose rickets or osteomalacia nationally and internationally. Therefore, we summarize the definition and pathogenesis of rickets and osteomalacia, and propose the diagnostic criteria and a flowchart for the differential diagnosis of various causes for these diseases. We hope that these criteria and flowchart are clinically useful for the proper diagnosis and management of patients with these diseases.

  19. Biodegradation of crude oil saturated fraction supported on clays.

    Science.gov (United States)

    Ugochukwu, Uzochukwu C; Jones, Martin D; Head, Ian M; Manning, David A C; Fialips, Claire I

    2014-02-01

    The role of clay minerals in crude oil saturated hydrocarbon removal during biodegradation was investigated in aqueous clay/saturated hydrocarbon microcosm experiments with a hydrocarbon degrading microorganism community. The clay minerals used for this study were montmorillonite, palygorskite, saponite and kaolinite. The clay mineral samples were treated with hydrochloric acid and didecyldimethylammonium bromide to produce acid activated- and organoclays respectively which were used in this study. The production of organoclay was restricted to only montmorillonite and saponite because of their relative high CEC. The study indicated that acid activated clays, organoclays and unmodified kaolinite, were inhibitory to biodegradation of the hydrocarbon saturates. Unmodified saponite was neutral to biodegradation of the hydrocarbon saturates. However, unmodified palygorskite and montmorillonite were stimulatory to biodegradation of the hydrocarbon saturated fraction and appears to do so as a result of the clays' ability to provide high surface area for the accumulation of microbes and nutrients such that the nutrients were within the 'vicinity' of the microbes. Adsorption of the saturated hydrocarbons was not significant during biodegradation.

  20. Formation of stable nanocomposite clays from small peptides reacted with montmorillonite and illite-smectite mixed layer clays

    Science.gov (United States)

    Block, K. A.; Katz, A.; LeBlanc, J.; Peña, S.; Gottlieb, P.

    2015-12-01

    Understanding how organic compounds interact with clay minerals and which functional groups result in the strongest bonds is pivotal to achieving a better understanding of how mineral composition affects the residence time of carbon and nitrogen in soils. In this work, we describe how small peptides derived from tryptone casein digest are dissolved and suspended with clay minerals to examine the nature of OM adsorption to mineral surfaces and the resulting effect on clay mineral structure. XRD analyses indicate that peptides intercalation results in expansion of the d001 spacing of montmorillonite (Mt) and the smectite component of a 70-30 illite-smectite mixed layer clay (I-S) and poorer crystallinity overall as a result of exfoliation of tactoids. Peptide adsorption is concentration-dependent, however, surface adsorption appears to mediate interlayer adsorption in Mt reaching a maximum of 16% of the mass of the organoclay complex, indicating that at a critical concentration, peptide intercalation will supersede surface adsorption resulting in a more stable attachment. In I-S the degree of surface adsorption and intercalation is proportional to concentration, however, surface adsorption is not a priming mechanism for interlayer adsorption. Thermogravimetric analysis of the organoclay complexes determined by TGA coupled to GC-MS indicate that the most prominent product species measured was 1-(1-Trimethylsiloxyethenyl)-3-trimethylsiloxy-benzene, likely from tryptophan monomer decomposition. The compound was detected over a broad temperature range, greater than 300 oC, during pyrolysis and suggests a carbon-silicon covalent bond formed between the peptide and tetrahedral layers in the clay. An additional silicon-bearing VOC detected at lower pyrolysis temperature by GC was N,N-Diethyl-1-(trimethylsilyl)-9,10-didehydroergoline-8-carboxamide, likely derived from a lysine-bearing peptide derivative. We hypothesize that hydrophobic (non-ionic) peptides react with silanol

  1. Clay nanocomposites for use in Li batteries

    Science.gov (United States)

    Moore, Gregory John

    1999-11-01

    Nanocomposites, materials made of more than one component and combined in an ordered manner on the nanometer scale, were synthesized using clay mineral hosts with various types of guests. The guests include polymers such as polyethylene oxide (PEO) and polyaniline (PANI), large molecules such as ethylmethyl sulfone, tetramethylene sulfone, and various length alkylamines. Vanadyl groups (VO 2+) were also incorporated with the clays. The otherwise non-swellable mica clay, synthetic Na-fluorophlogopite, was expanded by intercalation of acidic ions such as Cu2+ and Fe3+. As aqueous solutions, these ions caused the stable fluoromica to go from its dehydrated interlayer spacing of 9.8 A to over 14 A. This clay became a host for many other reactions including swelling with alkylamines to over 25 A. However, despite hydrated Cu2+ ions swelling fluorophlogopite, polymeric species such as PEO or PANI could not be inserted. Another clay that was used for formation of nanocomposites came from a procedure for the synthesis of Li-taeniolite, Li(Mg2Li)Si 4O10F2. The clay was synthesized following a high temperature method that led to a non-reactive product. Instead, a novel precursor route was employed that gave a clay product with a single hydration layer. Various chemical analyses gave a formula of Li0.8(Mg 2.2Li0.8)Si4O10(F1.6O 0.4)·H2O. For the purpose of forming nanocomposite electrolytes, ethylmethyl sulfone was synthesized and incorporated into the clay. For comparison of different shaped sulfones, tetramethylene sulfone also was inserted into the layers for electrolytic studies. To make a polymer-clay electrolyte, polyethylene oxide was intercalated into the Li-taeniolite. All of these new electrolyte materials were characterized using impedance spectroscopy for measurement of their conductivity. Syntheses and analyses are thoroughly discussed for all of these materials. Special attention is placed on powder x-ray diffraction and thermogravimetric techniques to

  2. Effect of clay minerals on low resistivity of Chang 6_1 reservoir in Wuqi area%吴起地区长6_1油层黏土矿物对油层低电阻率化的影响

    Institute of Scientific and Technical Information of China (English)

    周康; 刘佳庆; 段国英; 丁磊; 周邻丹

    2012-01-01

    为了认识黏土矿物对油层低电阻率化的影响,以薄片、扫描电镜、X射线衍射、测井解释和试油结果为依据,对吴起地区长61油层黏土矿物特征及其对电阻率的影响进行了研究。结果表明,黏土矿物对低电阻率油层的形成具有控制作用,具体表现在3个方面:第一为附加导电作用,以网状伊/蒙混层矿物最强,是油层电阻率降低的关键因素;第二为对孔隙结构的改造,导致束缚水饱和度增高,电阻率降低,以伊利石最为明显;第三是对水分子的吸附作用,以绿泥石等为主。综合三者的作用大小和矿物含量,吴起地区黏土矿物对电阻率的影响程度依次为:伊利石〉伊/蒙混层〉绿泥石〉高岭石。此项研究可对低电阻率油层的存在机理和分布进行有效解释和预测。%In order to understand the effect of clay minerals on low resistivity reservoirs,the slice,scanning electronic microscope,X-ray diffraction,logging interpretation and oil testing results were applied to study the effect of clay minerals on resistivity of Chang 61 reservoir in Wuqi area.The result shows that clay minerals play a dominate role on the forming of low resistivity reservoir.The role displays in the following three aspects: the role mainly is additional conductivity,and it is strongest in the illite/smectite mixed layer and is the key factor for resistivity decline;followed by the pore structure reformation which caused the bound water saturation increasing and resistivity decline,and it is most in illite;and then the absorption of water molecule which is mainly in chlorite.By considering the effects and mineral content,it was believed that the order of effect of clay minerals on resistivity is: illite illite/semectite mixed layer chlorite kaolinite.This study result can be used to interpret the mechanism and predict the distribution of low resistivity reservoir.

  3. Polymer-clay nanocomposites as precursors of nanostructured carbon materials for electrochemical devices: templating effect of clays.

    Science.gov (United States)

    Fernández-Saavedra, Rocío; Darder, Margarita; Gómez-Avilés, Almudena; Aranda, Pilar; Ruiz-Hitzky, Eduardo

    2008-04-01

    The present work introduces a comparative study on the use of polymer nanocomposites containing clay minerals of different structure, such as montmorillonite and sepiolite as host solids for the templating synthesis of carbon-like materials from different organic precursors. Carbon-clay nanocomposites were obtained by polymerization of either acrylonitrile or sucrose previously inserted in the pores of the clay minerals, followed by their further thermal transformation in carbon-like compounds. Acid treatment of the resulting carbon-clay nanocomposites removes the inorganic templates giving carbon-like materials with different textural features. Polymer-clay, carbon-clay and carbon-like materials have been characterized by applying spectroscopic techniques as FTIR and in situ EIS (electrochemical impedance spectroscopy) and other structural, textural and analytical tools (chemical analysis, XRD, SEM-EDX, TEM-EDX, N2 adsorption isotherms,...). Electrochemical properties of these carbon-clay nanocomposites, as well as their templated carbonaceous materials and their use as electrode materials of different electrochemical devices such as rechargeable Li-batteries, supercapacitors and electrochemical sensors, are also discussed.

  4. Clay fraction mineralogy of a Cambisol in Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Anastacio, A. S.; Fabris, J. D., E-mail: jdfabris@ufmg.br [Federal University of Minas Gerais, Campus - Pampulha, Department of Chemistry (Brazil); Stucki, J. W. [Department of Natural Resources and Environmental Sciences (United States); Coelho, F. S.; Pinto, I. V. [Federal University of Minas Gerais, Campus - Pampulha, Department of Chemistry (Brazil); Viana, J. H. M. [Embrapa Milho e Sorgo (Brazil)

    2005-11-15

    Clay minerals having a 2:1 (tetrahedral:octahedral sheet) structure may be found in strongly weathering soils only if the local pedo-climatic environment prevents them from further weathering to other minerals such as iron oxides. The clay minerals impart important chemical properties to soils, in part by virtue of changes in the redox state of iron in their crystal structures. Knowing the chemical nature of soil clays is a first step in evaluating their potential reactivity with other soil constituents and processes, such as the chemical decomposition of organic substrates to be potentially used in environmental remediation. The purpose of this work was to characterize the iron oxides and iron-bearing clay minerals from a B horizon of a Cambisol developed on tuffite in the State of Minas Gerais, Brazil, using chemical analysis, powder X-ray diffraction, Moessbauer spectroscopy, and thermal analysis. The iron oxides of this NaOH-treated clay-fraction were found to contain mainly maghemite ({gamma}Fe{sub 2}O{sub 3}) and superparamagnetic goethite ({alpha}FeOOH). Kaolinite (Al{sub 2}Si{sub 2}O{sub 5}(OH){sub 4}), smectite, and minor portions of anatase (TiO{sub 2}) were identified in the CBD-treated sample.

  5. Clay mineralogy in agrochernozems of western Ukraine

    Science.gov (United States)

    Papish, I. Ya.; Chizhikova, N. P.; Poznyak, S. P.; Varlamov, E. B.

    2016-10-01

    The mineralogy of clay fractions separated from deep low-humus deep-gleyic loamy typical agrochernozems on loess-like loams of the Upper Bug and Dniester uplands in the Central Russian loess province of Ukraine consists of complex disordered interstratifications with the segregation of mica- and smectite-type layers (hereafter, smectite phase), tri- and dioctahedral hydromicas, kaolinite, and chlorite. The distribution of the clay fraction is uniform. The proportions of the layered silicates vary significantly within the profile: a decrease in the content of the smectite phase and a relative increase in the content of hydromicas up the soil profile are recorded. In the upper horizons, the contents of kaolinite and chlorite increase, and some amounts of fine quartz, potassium feldspars, and plagioclases are observed. This tendency is observed in agrochernozems developed on the both Upper Bug and Dniester uplands. The differences include the larger amounts of quartz, potassium feldspars, and plagioclases in the clay material of the Upper Bug Upland, while the contents of the smectite phase in the soil profiles of the areas considered are similar. An analogous mineral association is noted in podzolized agrochernozems on loess-like deposits in the Cis-Carpathian region of the Southern Russian loess province developed on the Prut-Dniester and Syan-Dniester uplands. The distribution of particle-size fractions and the mineralogy of the clay fraction indicate the lithogenic heterogeneity of the soil-forming substrate. When the drifts change, the mineral association of the soils developed within the loess-like deposits gives place to minerals dominated by individual smectite with some mica-smectite inter stratifications, hydromicas, and chlorite.

  6. Induced polarization of clay-sand mixtures. Experiments and modelling.

    Science.gov (United States)

    Okay, G.; Leroy, P.

    2012-04-01

    The complex conductivity of saturated unconsolidated sand-clay mixtures was experimentally investigated using two types of clay minerals, kaolinite and smectite (mainly Na-Montmorillonite) in the frequency range 1.4 mHz - 12 kHz. The experiments were performed with various clay contents (1, 5, 20, and 100 % in volume of the sand-clay mixture) and salinities (distilled water, 0.1 g/L, 1 g/L, and 10 g/L NaCl solution). Induced polarization measurements were performed with a cylindrical four-electrode sample-holder associated with a SIP-Fuchs II impedance meter and non-polarizing Cu/CuSO4 electrodes. The results illustrate the strong impact of the CEC of the clay minerals upon the complex conductivity. The quadrature conductivity increases steadily with the clay content. We observe that the dependence on frequency of the quadrature conductivity of sand-kaolinite mixtures is more important than for sand-bentonite mixtures. For both types of clay, the quadrature conductivity seems to be fairly independent on the pore fluid salinity except at very low clay contents. The experimental data show good agreement with predicted values given by our SIP model. This complex conductivity model considers the electrochemical polarization of the Stern layer coating the clay particles and the Maxwell-Wagner polarization. We use the differential effective medium theory to calculate the complex conductivity of the porous medium constituted of the grains and the electrolyte. The SIP model includes also the effect of the grain size distribution upon the complex conductivity spectra.

  7. Macro-and Micro- Properties of Two Natural Marine Clays in China

    Institute of Scientific and Technical Information of China (English)

    JIANG Ming-jing; PENG Li-cai; ZHU He-hua; LIN Yi-xi; HUANG Liang-ji

    2009-01-01

    In this paper,macro- and micro- properties of natural marine clay in two different and representative regions of China are investigated in detail.In addition to in-situ tests,soil samples are collected by use of Shelby tubes for laboratory examination in Shanghai and Zhuhai respectively,two coastal cities in China.In the laboratory tests,macro-properties such as consolidation characteristics and undrained shear strength are measured.Moreover,X-ray diffraction test,scanning electron microscope test,and mercury intrusion test are carried out for the investigation of their micro-properties including clay minerals and microstructure.The study shows that:(1) both clays are Holocene series formations,classified as either normal or underconsolidated soils.The initial gradient of the stress-strain curves shows their increase with increasing consolidation pressure;however,the Shanghai and the Zhuhai clays are both structural soils with the latter shown to be more structured than the former.As a result,the Zhuhai clay shows strain softening behavior at low confining pressures,but strain hardening at high pressures.In contrast,the Shanghai clay mainly manifests strain-hardening.(2) An activity ranges from 0.75 to 1.30 for the Shanghai marine clay and from 0.5 to 0.85 for the Zhuhai marine clay.The main clay mineral is illite in the Shanghai clay and kaolinite in the Zhuhai clay.The Zhuhai clay is mainly characterized by a flocculated structure,while the typical Shanghai clay shows a dispersed structure.The porous structure of the Shanghai clay is characterized mainly by large and medium-sized pores,while the Zhuhai clay porous structure is mainly featreed by small and medium-sized pores.The differences in their macro- and micro- properties can he attributed to different sedimentation environments.

  8. Spectromicroscopy of Fe distributions in clay microcrystals

    Energy Technology Data Exchange (ETDEWEB)

    Grundl, T. [Univ. of Wisconsin, Milwaukee, WI (United States); Cerasari, S.; Garcia, A. [Lawrence Berkeley National Lab., CA (United States)] [and others

    1997-04-01

    Clays are ubiquitous crystalline particles found in nature that are responsible for contributing to a wide range of chemical reactions in soils. The structure of these mineral particles changes when the particle is hydrated ({open_quotes}wet{close_quotes}), from that when it is dry. This makes a study of the microscopic distribution of chemical content of these nanocrystals difficult using standard techniques that require vacuum. In addition to large structural changes, it is likely that chemical changes accompany the drying process. As a result, spectroscopic measurements on dried clay particles may not accurately reflect the actual composition of the material as found in the environment. In this work, the authors extend the use of the ALS Spectromicroscopy Facility STXM to high spectral and spatial resolution studies of transition metal L-edges in environmental materials. The authors are studying mineral particles of montmorillonite, which is an Fe bearing clay which can be prepared with a wide distribution of Fe concentrations, and with Fe occupying different substitutional sites.

  9. Autism Society

    Science.gov (United States)

    ... En Español Register today for the 49th Annual Autism Society National Conference Please plan on joining us ... Today Improving the lives of all affected by autism. The Autism Society is the nation's leading grassroots ...

  10. The composition and origin of Ghana medicine clays.

    Science.gov (United States)

    van Dongen, Bart E; Fraser, Sharon E; Insoll, Timothy

    2011-08-01

    The mineral, organic and elemental composition of medicine clays from three shrines in the Tong Hills in northern Ghana (Gbankil, Kusanaab, and Yaane) are assessed to ascertain what additives they might contain and the implications for their recognition, for example in archaeological contexts. These are clays that are widely used for healing purposes being perceived efficacious in curing multiple ailments and which are given a divine provenance, but their collection is ascribed human agency. The Yaane clay is also supplied as part of the process of obtaining the right to operate the shrine elsewhere making it widely dispersed. Organic geochemical analyses revealed a predominance of plant-derived material with a substantial contribution of microbial origin. Based on these (supported by elemental and mineral analyses), no unnatural organic material could be detected, making an exogenous contribution to these clays unlikely. The implications are that these are wholly natural medicinal substances with no anthropogenic input into their preparation, as the traditions suggest. The very similar mineralogy of all the clays, including a non-medicine clay sampled, suggests that, unless the geology radically differed, differentiating between them analytically in an archaeological contexts would be doubtful.

  11. Magnificent Clay Murals

    Science.gov (United States)

    Kirker, Sara Schmickle

    2007-01-01

    Each August, third grade artists at Apple Glen Elementary in Bentonville, Arkansas, start the school year planning, creating, and exhibiting a clay relief mural. These mural projects have helped students to acquire not only art knowledge and techniques, but an even more important kind of knowledge: what it means to plan and successfully complete a…

  12. Co-evolution of monsoonal precipitation in East Asia and the tropical Pacific ENSO system since 2.36 Ma: New insights from high-resolution clay mineral records in the West Philippine Sea

    Science.gov (United States)

    Yu, Zhaojie; Wan, Shiming; Colin, Christophe; Yan, Hong; Bonneau, Lucile; Liu, Zhifei; Song, Lina; Sun, Hanjie; Xu, Zhaokai; Jiang, Xuejun; Li, Anchun; Li, Tiegang

    2016-07-01

    Clay mineralogical analysis and scanning electron microscope (SEM) analysis were performed on deep-sea sediments cored on the Benham Rise (core MD06-3050) in order to reconstruct long-term evolution of East Asian Summer Monsoon (EASM) rainfall in the period since 2.36 Ma. Clay mineralogical variations are due to changes in the ratios of smectite, which derive from weathering of volcanic rocks in Luzon Island during intervals of intensive monsoon rainfall, and illite- and chlorite-rich dusts, which are transported from East Asia by winds associated with the East Asian Winter Monsoon (EAWM). Since Luzon is the main source of smectite to the Benham Rise, long-term consistent variations in the smectite/(illite + chlorite) ratio in core MD06-3050 as well as ODP site 1146 in the Northern South China Sea suggest that minor contributions of eolian dust played a role in the variability of this mineralogical ratio and indicate strengthening EASM precipitation in SE Asia during time intervals from 2360 to 1900 kyr, 1200 to 600 kyr, and after 200 kyr. The EASM rainfall record displays a 30 kyr periodicity suggesting the influence of El Niño-Southern Oscillation (ENSO). These intervals of rainfall intensification on Luzon Island are coeval with a reduction in precipitation over central China and an increase in zonal SST gradient in the equatorial Pacific Ocean, implying a reinforcement of La Niña-like conditions. In contrast, periods of reduced rainfall on Luzon Island are associated with higher precipitation in central China and a weakening zonal SST gradient in the equatorial Pacific Ocean, thereby suggesting the development of dominant El Niño-like conditions. Our study, therefore, highlights for the first time a long-term temporal and spatial co-evolution of monsoonal precipitation in East Asia and of the tropical Pacific ENSO system over the past 2.36 Ma.

  13. Characterization of karak clay from pakistan for pharmaceutical and cosmetic applications

    Energy Technology Data Exchange (ETDEWEB)

    Shah, L.A. [University of Peshawar (Pakistan); Silva-Valenzuela, M.G.; Valenzuela-Diaz, F.R.; Sayeg, I.J.; Carvalho, F.M.S. [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil)

    2012-07-01

    Full text: Clay, the most important, plentiful, and low cost naturally occurring mineral, is widely used in variety of industrial application including Pharmaceutical and cosmetic. Clay is the fine grained aluminosilicate mineral which shows the property of plasticity at appropriate water content, and becomes hard upon drying. In Pakistan there are different types of clay but till now neither of them properly identified nor characterize for specific industrial application. The objective of this work is to characterize Karak clay for pharmaceutical and cosmetic applications collected from deposit located at Shagai region, District Karak, Pakistan. The clay was characterized through Xray diffractometry (XRD), X-ray Fluorescence (XRF), trace elemental Analysis, Microbiological analysis, Cation exchange capacity (CEC), pH and swelling assays according to European, United States of America and Brazilian Pharmacopeias. Bulk Chemical analysis shows that the Aluminum oxide and silica oxide are present in large quantity which was confirmed by XRD that this sample has montmorillonite as a major while illite and kaolinite as minor clay minerals. Quartz of small quantity was also found as a non-clay mineral. After analyzing the results for sample it was concluded that the clay is a strong candidate for cosmetic purposes. (author)

  14. 泥质烃源岩中粘土矿物结合有机质热演化的红外发射光谱研究%Infra-red emission spectroscopy study of thermal evolution of organic matter bound by clay minerals in muddy hydrocarbon source rocks

    Institute of Scientific and Technical Information of China (English)

    卢龙飞; 蔡进功; 刘文汇; 腾格尔; 胡文瑄

    2012-01-01

    选取济阳坳陷古近系渐新统沙河街组泥质烃源岩,进行小于2μm的粘土组分提取,运用红外发射光谱技术研究粘土矿物结合有机质的热演化过程和有机—粘土相互作用对有机质热演化过程的影响.结果显示,代表脂肪链结构的甲基、亚甲基振动吸收峰随着温度的升高,强度逐渐降低,烷基链由于受到粘土保护而晚于支链分解;代表芳香结构的芳环的振动吸收峰强度变化较为复杂,798,779,750 cm-1等峰随温度升高而减弱,而1 600 cm-1和3 030 cm-1峰则在200℃左右才出现并不断增强,随后慢慢减弱,且芳香度指数一直增加,显示出明显的芳构化过程.同时,粘土矿物层间水合阳离子通过“水桥”机制将含羧基的有机分子结合起来,对其演化有抑制作用.红外发射光谱研究揭示出粘土矿物结合的有机质主要通过脂肪族化合物的芳构化转化实现生烃的演化特征,是烃源岩热演化研究的有效手段.%To examine the thermal evolution of and the influence of organo-clay interaction on organic matter bound by clay minerals in muddy source rocks, we studied the <2 μm particle-size fractions extracted from hydrocarbon source rocks in Neocene, Jiyang Depression, eastern China, using infra-red emission spectroscopy (IES). Results show that the vibration peaks of methylene and methyl representing aliphatic chain decrease with the increasing of temperature, and lateral chains are easily to subject to oxidation than main chains. Intensities of vibration peaks attributed to aromatic compounds vary respectively, some peaks such as 798, 779 and 750 cm-1 decrease with the increasing of temperature, but the reverse to other peaks. Vibration peaks such as 1 600 and 3 030 cm-1 do not occur until 250℃ and increase first and decrease subsequently, while aromaticity factor increases progressively, showing a clear aromatization process. Also, carboxylic acids interact with interlayer hydrated

  15. Clay Animals and Their Habitats

    Science.gov (United States)

    Adamson, Kay

    2010-01-01

    Creating clay animals and their habitats with second-grade students has long been one of the author's favorite classroom activities. Students love working with clay and they also enjoy drawing animal homes. In this article, the author describes how the students created a diorama instead of drawing their clay animal's habitat. This gave students…

  16. Clay mineralogy of innershelf sediments off Cochin, west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Reddy, N.P.C.; Rao, N.V.N.D.; Dora, Y.L.

    Kaolinite, montmorillonite and illite are the clay minerals occurring in decreasing order of abundance in the Holocene sediments of inner shelf and adjacent coastal environments of Cochin Region. Southern part of Vembanad Lake, estuarine part...

  17. Origin of Quaternary Red Clay of Southern Anhui Province

    Institute of Scientific and Technical Information of China (English)

    HUXUEFENG; YUANGUODONG; 等

    1998-01-01

    The particle-size distribution,heavy mineral constituents and rare earth elements(REE) characteristics of the Quaternary red clay of southern Anhui Province were studied to explore the origin of the clay.The results showed that the clay had some properties of areolian deposits,which could be compared with,those of the loess in North China ;and its chondrite-normalized curves of REE were similar to those of the Xiashu loess implying tha they shared the same orighin.It was concluded in combination with the results rported by other researchers that the Quaternary red clay of southern Anhui Province originated from aolian deposts, and this could reveal the cycles of warm and cold climates in the area during the Quaternary period.

  18. Clay membrane made of natural high plasticity clay:

    DEFF Research Database (Denmark)

    Foged, Niels; Baumann, Jens

    1999-01-01

    Leachate containment in Denmark has throughout the years been regulated by the DIF Recommendation for Sanitary Landfill Liners (DS/R4669. It states that natural clay deposits may be used as membrane material provided the membrane and drainage system contains at least 95% of all leachate created...... into account advective ion transport as well as diffusion. Clay prospecting for clays rich in smectite has revealed large deposits of Tertiary clay of very high plasticity in the area around Rødbyhavn on the Danish island of Lolland. The natural clay contains 60-75% smectite, dominantly as a sodium......-type. The clay material has been evaluated using the standardized methods related to mineralogy, classification, compaction and permeability, and initial studies of diffusion properties have been carried out. Furthermore, at a test site the construction methods for establishing a 0.15-0.3 m thick clay membrane...

  19. Can we map swelling clays with remote sensing?

    Science.gov (United States)

    van der Meer, Freek

    Swelling soils are soils containing clay minerals that change volume with water content. The original volume of natural soils may change up to 150 percent with increasing water content, which creates major geological hazards that cause extensive damage worldwide. Current engineering practice for delineating areas of potential high swell builds on extensive laboratory analysis, including X-ray diffraction analysis for establishing clay mineralogy and Atterberg limits for deriving the swelling index. This is labour-intensive and thus expensive. Of key importance in assessing the swelling potential of soils is accurate mapping of clay mineralogy and amount (particularly of high swelling smectite and low swelling kaolinite-group minerals) and mapping of soil moisture. For applications related to slope instability processes, surface height and surface deformation need to be examined. Results from spectral analysis of clay mineral spectra presented in this paper show that careful examination of absorption bands allows the characterization and mapping of the clay mineralogy of the soil, which, in conjunction with spectral unmixing, may lead to surface fractions of the various clay minerals. This can potentially be empirically linked with current engineering tests. Remote sensing perspectives for spatial reproduction of these results are further examined in this paper. Imaging spectrometry ( ie, data acquisition in many narrow spectral bands that allow images of reflectance spectra to be derived) may provide insight in surface mineralogy, while microwave remote sensing could deliver soil moisture information. Interferometric SAR (InSAR) is one method of remotely sensed elevation mapping; other remote sensing approaches include radar and laser altimetry and the derivation of digital terrain data from stereoscopic imagery ( ie, Spot, MOMS, etc). This paper could form the basis for formulating a number of research projects within a framework of mapping swelling potential of

  20. COMPOSITION OF MINERAL PHASES OF THE GHIDIRIM DIATOMITE

    Directory of Open Access Journals (Sweden)

    Vasile Rusu

    2007-06-01

    Full Text Available Studies of the mineralogical composition of diatomite from the Ghidirim location of RM, as well as of the extracted clay phase are presented. The mineral phase of the diatomite contains a number of clay minerals, like montmorillonite (in a mixture with insignificant quantities of slightly chloritized montmorillonite, illite and kaolinite. Diatomite contains also non-clay components as fine-dispersed quartz and amorphous material, the more probable sources of which are opal, amorphous alumosilicates, aluminum and iron hydroxides. The applied procedure for separation of clay fractions by sizing settling in liquid media proves to be very useful, enabling possibilities for more accurate identification of the clay constituents of diatomic material. Procedure allows to separate very clean clay fraction especially rich in montmorillonite, which can be utilized itself as mineral adsorbent for practical purposes.

  1. Planetary Society

    Science.gov (United States)

    Murdin, P.

    2000-11-01

    Carl Sagan, Bruce Murray and Louis Friedman founded the non-profit Planetary Society in 1979 to advance the exploration of the solar system and to continue the search for extraterrestrial life. The Society has its headquarters in Pasadena, California, but is international in scope, with 100 000 members worldwide, making it the largest space interest group in the world. The Society funds a var...

  2. Texturas, argilominerales y metales en sedimentos de fondo de arroyos de la franja costera sur del Río de la Plata Textures, clay minerals and heavy metals in river bottom sediments from southern río de la Plata

    Directory of Open Access Journals (Sweden)

    Marcelo Manassero

    2010-08-01

    Full Text Available Se estudiaron sedimentos de fondo extraídos en posiciones distales de los arroyos El Pescado, Cañada Arregui, Buriñigo, Juan Blanco, El Destino, Samborombón y Salado, estos dos últimos ubicados en la región más abierta del estuario del río de la Plata. Para la caracterización granulométrica (tamizado y pipeteo, mineralogía de arcillas (difracción rayos X, contenido de materia orgánica (digestión ácida en caliente, valoración titulométrica y concentración de metales (espectrometría AA, se emplearon métodos estandarizados de laboratorio. La mayoría de los sedimentos fueron clasificados como limos arcillosos y arcillas limosas, sin embargo en el río Salado y los arroyos El Pescado y El Destino los sedimentos de fondo son más arenosos. La composición mineralógica de las arcillas indica que los sedimentos de los arroyos cuentan con una importante proporción de esmectita y caolinita, aunque manteniéndose una predominancia illítica. Significativamente, mayor proporción de caolinita está presente en los ríos Samborombón y Salado, evidenciando una importante influencia estuárica. El hierro y el manganeso son los metales mayoritarios con mayor variabilidad entre cursos. Los humedales costeros y zonas deprimidas de la costa del estuario favorecen la retención de estos dos elementos. Las altas variaciones de los contenidos reflejan diferencias fisicoquímicas en los ambientes depositacionales. El orden de abundancia del resto de los metales analizados es Zn>Pb=Cu>Cr> Ni>Cd, con concentraciones más elevadas en los de la vertiente sur del estuario, manteniendo un comportamiento similar al de los mayoritarios.River bottom sediments from distal positions of El Pescado, Cañada Arregui, Buriñigo, Juan Blanco, El Destino streams, and Samborombón and Salado rivers from the southern coastal area of the río de la Plata estuary were studied. Grain size analysis, clay mineralogy (X ray diffraction, organic matter content (by acid

  3. Geotechnical variability of permafrozen glaciomarine clays in Sdr. Strømfjord in Greenland

    DEFF Research Database (Denmark)

    Foged, Niels Nielsen; Ingeman-Nielsen, Thomas; Belmonte, Louise Josefine

    2014-01-01

    -going in the area at Strømfjordshavn. The C14 datings of marine shells collected on the marine clay terraces at level 300kPa. Clay minerals were weathered causing moderate to high activity and plasticity despite the formation age of only 7000 years. (b) The "River Bank Erosion Cut" 2 km east of the Airport Terminal....... We studied a frozen marine clay deposit at +35 m with stratified ice layers under sandy gravel top layer. During laboratory analysis using fall cone testing a thawed clay sample was found to be quick (St>700) due to dilution of pore water salts. Multidisciplinary approach was necessary for this study....

  4. A Study of Clay-Epoxy Nanocomposites Consisting of Unmodified Clay and Organo Clay

    Directory of Open Access Journals (Sweden)

    Graham Edward

    2006-04-01

    Full Text Available Clay-epoxy nanocomposites were synthesized from DGEBA resin and montmorillonite clay with an in-situ polymerization. One type of untreated clay and two types of organo clay were used to produce the nanocompsoites. The aims of this study were to examine the nanocomposite structure using different tools and to compare the results between the unmodified clay and modified clays as nanofillers. Although diffractogram in reflection mode did not show any apparent peak of both types of materials, the transmitted XRD (X-Ray Difraction graphs, DSC (Differential Scanning Calorimeter analysis and TEM (Transmission Electron Microscope images revealed that the modified clay-epoxy and unmodified clay-epoxy provides different results. Interestingly, the micrographs showed that some of the modified clay layers possessed non-exfoliated layers in the modified clay-epoxy nanocomposites. Clay aggregates and a hackle pattern were found from E-SEM images for both types of nanocomposite materials. It is shown that different tools should be used to determine the nanocomposite structure.

  5. Impact of Oriented Clay Particles on X-Ray Spectroscopy Analysis

    Science.gov (United States)

    Lim, A. J. M. S.; Syazwani, R. N.; Wijeyesekera, D. C.

    2016-07-01

    Understanding the engineering properties of the mineralogy and microfabic of clayey soils is very complex and thus very difficult for soil characterization. Micromechanics of soils recognize that the micro structure and mineralogy of clay have a significant influence on its engineering behaviour. To achieve a more reliable quantitative evaluation of clay mineralogy, a proper sample preparation technique for quantitative clay mineral analysis is necessary. This paper presents the quantitative evaluation of elemental analysis and chemical characterization of oriented and random oriented clay particles using X-ray spectroscopy. Three different types of clays namely marine clay, bentonite and kaolin clay were studied. The oriented samples were prepared by placing the dispersed clay in water and left to settle on porous ceramic tiles by applying a relatively weak suction through a vacuum pump. Images form a Scanning Electron Microscope (SEM) was also used to show the comparison between the orientation patterns of both the sample preparation techniques. From the quantitative analysis of the X-ray spectroscopy, oriented sampling method showed more accuracy in identifying mineral deposits, because it produced better peak intensity on the spectrum and more mineral content can be identified compared to randomly oriented samples.

  6. Clay exfoliation and polymer/clay aerogels by supercritical carbon dioxide

    Directory of Open Access Journals (Sweden)

    Simona eLongo

    2013-11-01

    Full Text Available Supercritical carbon dioxide (scCO2 treatments of a montmorillonite (MMT intercalated with ammonium cations bearing two long hydrocarbon tails (organo-modified MMT, OMMT led to OMMT exfoliation, with loss of the long-range order in the packing of the hydrocarbon tails and maintenance of the long-range order in the clay layers. The intercalated and the derived exfoliated OMMT have been deeply characterized, mainly by X-ray diffraction analyses. Monolithic composite aerogels, with large amounts of both intercalated and exfoliated OMMT and including the nanoporous-crystalline δ form of syndiotactic polystyrene (s-PS, have been prepared, by scCO2 extractions of s-PS-based gels. Also for high OMMT content, the gel and aerogel preparation procedures occur without re-aggregation of the exfoliated clay, which is instead observed for other kinds of polymer processing. Aerogels with the exfoliated OMMT have more even dispersion of the clay layers, higher elastic modulus and larger surface area than aerogels with the intercalated OMMT. Extremely light materials with relevant transport properties could be prepared. Moreover, s-PS-based aerogels with exfoliated OMMT could be helpful for the handling of exfoliated clay minerals.

  7. The impact of mantle source CO2 on clay minerals of clastic reservoirs in the east part of Shijiutuo symon fault, Bozhong depression%渤中坳陷石臼陀凸起东段幔源CO2充注对储集层粘土矿物的影响

    Institute of Scientific and Technical Information of China (English)

    王清斌; 臧春艳; 朱文森; 赵国祥; 袁志刚; 冯冲

    2012-01-01

    探讨了渤中坳陷石臼陀凸起东段CO2来源及CO2充注对储层粘土矿物的影响.研究表明,CO2中δ13C组成较重,R/Ra值较大,CO2为幔源成因;控盆的深大断裂是CO2的主要运移通道;CO2热流体晚期充注对砂岩储集层粘土矿物产生了明显的影响:CO2热流体侵位后形成的热波动效应加快了储集层中伊蒙混层粘土的演化,含CO2储集层中伊蒙混层中蒙脱石含量要比同深度的泥岩低15% ~30%;CO2热流体晚期侵入加剧了长石的溶蚀作用,长石溶蚀促进了自生高岭石的大量形成;CO2热流体侵位后形成的偏酸性环境抑制伊利石生长,促进了其他粘土矿物向高岭石转化;含CO2储集层以少见的高自生高岭石、低伊利石为特征,这对储层物性改善起到了决定性的影响.%The origin of CO2 and the alteration of CO2 into clay minerals in eastern Shijiutuo symon fault of Bozhong depression were studied in this paper. The elevated δ13C and R/Ra values show the mantle-derivation of CO2. The basm-controlling deep fault was the main migration pathway of CO2 fluid. CO2 fluid injection had obvious impact on clay minerals. CO2 late injection caused obvious thermal fluctuation and brought out the result that the montmorillonite of the illite/montmorillonite mixing layer was 15% ~30% lower than that of mudstone at the nearby depth. Because of late accumulation of C&i, acidic environment of reservoir bed lasted for a long time, which promoted dissolution of feldspar and formation of kaolinite. Acidic environment inhibited illite in favor of the transform of other clay minerals into kaolinite. The CO2-bearing reservoir bed was characterized by high authigenic kaolinites and low illite, which played a decisive role in reservoir quality improvement.

  8. Modelling iron clay interactions in deep geological disposal conditions

    Science.gov (United States)

    Bildstein, O.; Trotignon, L.; Perronnet, M.; Jullien, M.

    In the context of deep geological disposal of high level radioactive wastes, the interactions between iron and clay-rich materials may lead to adverse transformations of clay minerals with a potential loss of confining properties such as swelling and capacity to exchange cations. Such transformations have been experimentally observed at temperatures starting at ca. 80 °C, where smectites contained in a mixture of bentonite and iron powder are transformed into iron-rich serpentine-type minerals. The reaction-transport code CRUNCH is used to investigate the iron-clay interactions at 50 °C over a period of 10,000 years, which are the conditions considered here to represent the mean temperature value and the expected timescale for the corrosion stage. The aim is to predict the nature and quantity of corrosion product, calculate the chemistry of water (essentially the pH) and the mineralogical transformation in the system containing the canister, an optional engineered barrier (bentonite) and the host-rock (argillite). The results of the calculations show that at the interface with the canister, where steel corrosion occurs, the iron is partly immobilized by the precipitation of iron oxides (essentially magnetite) and small amounts of siderite. The pH stabilizes at high values, between 10 and 11, at this location. In the bentonite or the argillite in contact with the container, the primary clay minerals are destabilized and iron-rich serpentine-like minerals precipitate as observed in the experiments (cronstedtite and berthierine). These minerals show low cation exchange and swelling capacities. The results also show that the interactions between iron and clay may lead to significant porosity changes in the system. A reduction of the porosity is predicted at the surface of the steel canister, due to the precipitation of iron oxides. Porosity increase is predicted in the clay material due to the dissolution of the primary clay minerals. The effect of these porosity

  9. Distribution characteristics and source analysis of clay minerals contents in surface sediments of the northwestern South China Sea%南海北部西侧海域粘土矿物的含量分布特征及来源分析

    Institute of Scientific and Technical Information of China (English)

    张晓飞; 陈坚; 徐勇航; 赖志坤

    2012-01-01

    Clay components <2 )i,m of 315 surface sediment samples are analyzed by XRD. The results indicate that clay minerals consist of illite, chlorite, smectite and kaolinite. Distribution character of the clay minerals is signifi cantly different in different parts of the research area. Based on the distribution character of clay minerals and topography of the research area, the research area can be divided into three parts; A area is the continental shelf off Pearl River; B area is the eastern continental shelf and the slope off the Hainan Island; C area is from Xisha Trough to the Xisha Islands waters. Based on the distribution characteristics of the clay minerals in the research area and surrounding rivers, it is found that kaolinite(mean 19% )of A area is from Pearl River, illite(mean 53% ) and chlorite(mean 18% ) mainly from Taiwan, with low amount of smectite( mean 10% ). Kaolinite( mean 13% ) of B area is mainly from Hainan Island, smectite( mean 16% ) mainly from Luzon Island. Smectite( mean 14% ) of C area is mainly from rivers of middle Vietnam and the Red River, with low (mean 12% ) kaolinite content. Illite and chlorite of west B and C area are mainly from rivers of middle Vietnam and the Red River, while illite and chlorite of east B and C area are mainly from Taiwan rivers.%应用X射线衍射(XRD)方法对南海北部西侧海域315个表层沉积物<2μm的粘土组分进行分析.结果表明,本研究区粘土矿物有伊利石、绿泥石、蒙脱石和高岭石,其组合特征在不同区域表现出明显的差异.根据粘土矿物的空间分布特征以及研究区的海底地形特征,研究区大致可以分为3个不同区块:A区是珠江口外的大陆架区域;B区是海南岛以东陆架陆坡区域;C区为西沙海槽至西沙群岛附近区域.根据研究区表层粘土矿物分布特征、周围河流供给的主要粘土成分以及洋流搬运作用,发现A区高岭石(平均含量为19%)主要来自珠江,伊利石与绿

  10. Adsorption of hydrogen gas and redox processes in clays.

    Science.gov (United States)

    Didier, Mathilde; Leone, Laura; Greneche, Jean-Marc; Giffaut, Eric; Charlet, Laurent

    2012-03-20

    In order to assess the adsorption properties of hydrogen gas and reactivity of adsorbed hydrogen, we measured H(2)(g) adsorption on Na synthetic montmorillonite-type clays and Callovo-Oxfordian (COx) clayrock using gas chromatography. Synthetic montmorillonites with increasing structural Fe(III) substitution (0 wt %, 3.2 wt %, and 6.4 wt % Fe) were used. Fe in the synthetic montmorillonites is principally present as structural Fe(III) ions. We studied the concomitant reduction of structural Fe(III) in the clays using (57)Fe Mössbauer spectrometry. The COx, which mainly contains smectite/illite and calcite minerals, is also studied together with the pure clay fraction of this clayrock. Experiments were performed with dry clay samples which were reacted with hydrogen gas at 90 and 120 °C for 30 to 45 days at a hydrogen partial pressure close to 0.45 bar. Results indicate that up to 0.11 wt % of hydrogen is adsorbed on the clays at 90 °C under 0.45 bar of relative pressure. (57)Fe Mössbauer spectrometry shows that up to 6% of the total structural Fe(III) initially present in these synthetic clays is reduced upon adsorption of hydrogen gas. No reduction is observed with the COx sample in the present experimental conditions.

  11. Characterisation of the wall-slip during extrusion of heavy-clay products

    Science.gov (United States)

    Kocserha, I.; Gömze, A. L.; Kulkov, S.; Kalatur, E.; Buyakova, S. P.; Géber, R.; Buzimov, A. Y.

    2017-01-01

    During extrusion through the extrusion die, heavy-clay compounds are usually show plug flow with extensive slip at the wall of the die. In this study, the viscosity and the thickness of the slip layer were investigated. For the examination a brick-clay from Malyi (Hungary) deposit was applied as a raw material. The clay was characterised by XRPD, BET, SEM and granulometry. As the slip layer consists of suspension of the fine clay fraction so the clay minerals content of the clay (dwater content was measured by means of rotational viscosimeter. The thickness of the slip layer was calculated from the measured viscosity and other data obtained from an earlier study with capillary rheometer. The calculated thickness value showed a tendency to reach a limit value by increasing the extrusion speed.

  12. The effects of worms, clay and biochar on CO2 emissions during production and soil application of co-composts

    Science.gov (United States)

    Barthod, Justine; Rumpel, Cornélia; Paradelo, Remigio; Dignac, Marie-France

    2016-12-01

    In this study we evaluated CO2 emissions during composting of green wastes with clay and/or biochar in the presence and absence of worms (species of the genus Eisenia), as well as the effect of those amendments on carbon mineralization after application to soil. We added two different doses of clay, biochar or their mixture to pre-composted green wastes and monitored carbon mineralization over 21 days in the absence or presence of worms. The resulting co-composts and vermicomposts were then added to a loamy Cambisol and the CO2 emissions were monitored over 30 days in a laboratory incubation. Our results indicated that the addition of clay or clay/biochar mixture reduced carbon mineralization during co-composting without worms by up to 44 %. In the presence of worms, CO2 emissions during composting increased for all treatments except for the low clay dose. The effect of the amendments on carbon mineralization after addition to soil was small in the short term. Overall, composts increased OM mineralization, whereas vermicomposts had no effect. The presence of biochar reduced OM mineralization in soil with respect to compost and vermicompost without additives, whereas clay reduced mineralization only in the composts. Our study indicates a significant role of the conditions of composting on mineralization in soil. Therefore, the production of a low CO2 emission amendment requires optimization of feedstocks, co-composting agents and worm species.

  13. CHEMICAL AND MINERALOGICAL CHARACTERISTICS OF FRENCH GREEN CLAYS USED FOR HEALING.

    Science.gov (United States)

    Williams, Lynda B; Haydel, Shelley E; Giese, Rossman F; Eberl, Dennis D

    2008-08-01

    The worldwide emergence of infectious diseases, together with the increasing incidence of antibiotic-resistant bacteria, elevate the need to properly detect, prevent, and effectively treat these infections. The overuse and misuse of common antibiotics in recent decades stimulates the need to identify new inhibitory agents. Therefore, natural products like clays, that display antibacterial properties, are of particular interest.The absorptive properties of clay minerals are well documented for healing skin and gastrointestinal ailments. However, the antibacterial properties of clays have received less scientific attention. French green clays have recently been shown to heal Buruli ulcer, a necrotic or 'flesh-eating' infection caused by Mycobacterium ulcerans. Assessing the antibacterial properties of these clays could provide an inexpensive treatment for Buruli ulcer and other skin infections.Antimicrobial testing of the two clays on a broad-spectrum of bacterial pathogens showed that one clay promotes bacterial growth (possibly provoking a response from the natural immune system), while another kills bacteria or significantly inhibits bacterial growth. This paper compares the mineralogy and chemical composition of the two French green clays used in the treatment of Buruli ulcer.Mineralogically, the two clays are dominated by 1Md illite and Fe-smectite. Comparing the chemistry of the clay minerals and exchangeable ions, we conclude that the chemistry of the clay, and the surface properties that affect pH and oxidation state, control the chemistry of the water used to moisten the clay poultices and contribute the critical antibacterial agent(s) that ultimately debilitate the bacteria.

  14. Feldspar minerals as efficient deposition ice nuclei

    Directory of Open Access Journals (Sweden)

    J. D. Yakobi-Hancock

    2013-06-01

    Full Text Available Mineral dusts are well known to be efficient ice nuclei, where the source of this efficiency has typically been attributed to the presence of clay minerals such as illite and kaolinite. However, the ice nucleating abilities of the more minor mineralogical components have not been as extensively examined. As a result, the deposition ice nucleation abilities of 24 atmospherically-relevant mineral samples have been studied, using a continuous flow diffusion chamber at −40.0 ± 0.3 °C. The same particle size (200 nm and particle preparation procedure were used throughout. The ice nucleation behaviour of the pure minerals is compared to that of complex mixtures, such as Arizona Test Dust (ATD and Mojave Desert Dust (MDD, and to lead iodide, which has been previously proposed for cloud seeding. Lead iodide was the most efficient ice nucleus (IN, requiring a critical relative humidity with respect to ice (RHi of 122.0 ± 2.0% to activate 0.1% of the particles. MDD (RHi 126.3 ± 3.4% and ATD (RHi 129.5 ± 5.1% have lower but comparable activity. From a set of clay minerals (kaolinite, illite, montmorillonite, non-clay minerals (e.g. hematite, magnetite, calcite, cerussite, quartz, and feldspar minerals (orthoclase, plagioclase present in the atmospheric dusts it was found that the feldspar minerals (particularly orthoclase, and not the clays, were the most efficient ice nuclei. Orthoclase and plagioclase were found to have critical RHi values of 127.1 ± 6.3% and 136.2 ± 1.3%, respectively. The presence of feldspars (specifically orthoclase may play a significant role in the IN behaviour of mineral dusts despite their lower percentage in composition relative to clay minerals.

  15. Removal of waterborne microorganisms by filtration using clay-polymer complexes.

    Science.gov (United States)

    Undabeytia, Tomas; Posada, Rosa; Nir, Shlomo; Galindo, Irene; Laiz, Leonila; Saiz-Jimenez, Cesareo; Morillo, Esmeralda

    2014-08-30

    Clay-polymer composites were designed for use in filtration processes for disinfection during the course of water purification. The composites were formed by sorption of polymers based on starch modified with quaternary ammonium ethers onto the negatively charged clay mineral bentonite. The performance of the clay-polymer complexes in removal of bacteria was strongly dependent on the conformation adopted by the polycation on the clay surface, the charge density of the polycation itself and the ratio between the concentrations of clay and polymer used during the sorption process. The antimicrobial effect exerted by the clay-polymer system was due to the cationic monomers adsorbed on the clay surface, which resulted in a positive surface potential of the complexes and charge reversal. Clay-polymer complexes were more toxic to bacteria than the polymers alone. Filtration employing our optimal clay-polymer composite yielded 100% removal of bacteria after the passage of 3L, whereas an equivalent filter with granular activated carbon (GAC) hardly yielded removal of bacteria after 0.5L. Regeneration of clay-polymer complexes saturated with bacteria was demonstrated. Modeling of the filtration processes permitted to optimize the design of filters and estimation of experimental conditions for purifying large water volumes in short periods.

  16. Property and performance amelioration of pelagic clay from the East Pacific

    Institute of Scientific and Technical Information of China (English)

    Peiping ZHANG; Shufeng LIU; Xuefa SHI; Huahua LU; Juanjuan LIU; Xiaoguo CHI

    2008-01-01

    To make use of the pelagic clay as polymer filling, the properties of clay sediments from the ocean investigation zone of China in the East Pacific were studied by the SSA, XRF, ICP/MAS, FHR, XRD, SEM, DTA/TG and granularity distributing etc. , and experiments were settled to improve the whiteness and activation of the clay based on these data. Compared with land clay, pelagic clay holds many particular features, such as fine particles and incompact accumulation, worse crystallization and more defects, high activity, complex mineral and chemical components, and low whiteness etc. Processing the purified pelagic clay with acids and zinc, then baked it at different temperatures, the whiteness of clay can be increased from 23.8% to 73.1%, and the optimized conditions is : consistency of vitriol 25%, ratio of clay to water 4:1, reaction time 4h, reaction temperature 90℃, dosage of zinc 2.0 g/L, and baking temperature 700℃. And the SSA of whited clay is increased too. Using the dry milling method to modify the pelagic clay with organic reagents, the optimized technique is KH550, concentration 1.5%, reaction time 20 min. XRD,FTIR and SEM testing indicate that the mechanism of organic activation was mainly surface absorbing and chemical combination secondly.

  17. 80 FR 65469 - NESHAP for Brick and Structural Clay Products Manufacturing; and NESHAP for Clay Ceramics...

    Science.gov (United States)

    2015-10-26

    ... Clay Products Manufacturing; and NESHAP for Clay Ceramics Manufacturing; Final Rule #0;#0;Federal...; and NESHAP for Clay Ceramics Manufacturing AGENCY: Environmental Protection Agency (EPA). ACTION... NESHAP for Clay Ceramics Manufacturing. All major sources in these categories must meet...

  18. Clay vein and its implication for uranium exploration activity in the northern part of the Alligator Rivers Uranium Field, northern Australia

    Energy Technology Data Exchange (ETDEWEB)

    Sasao, Eiji [Japan Nuclear Cycle Development Inst., Toki, Gifu (Japan). Tono Geoscience Center

    2003-07-01

    Clay veins have been found by uranium exploration drilling around the Black Rock uranium prospect in the northern part of the alligator Rivers Uranium Field (ARUF), northern Australia. The mineralogical and chemical features are described to clarify relations with uranium mineralization, because it is not accompanied by uranium mineralization. X-ray diffraction and chemical analysis for major elements indicate that the clay vein consists mainly of chlorite (clinochlore to ferroan clinochlore) and lesser mica clay mineral (t-1M dominant). The clay vein is compared with the clay alteration zone around the uranium deposits in ARUF in terms of mode of occurrence, mineral and chemical compositions. Mineral composition of the clay vein is only in accordance with that of the inner alteration halo of the clay alteration zone. It is, however, different from mineral composition of the outer alteration halo in terms of lack of Fe chlorite in the clay vein. Chemical composition of the clay vein is similar to that of the clay alteration zone, except for lack in the vein of high iron content which is observed in some samples of the alteration zone. As a whole, the feature of the clay vein corresponds to the inner alteration zone around the uranium deposit in ARUF. The mode of occurrence of the clay vein is very different from that of the clay alteration zone. Mode of occurrence, and mineral and chemical compositions of the clay vein resemble a chlorite vein in the Lower to Middle Proterozoic sandstone above the Jabiluka deposit, one of major uranium deposit in the ARUF. Because of the similarity between the clay and the chlorite veins, the clay vein is regarded as marginal facies of an alteration zone. The fluid that formed the clay vein is estimated to have been oxidized, because of the existence of hematite and ubiquitous Mg chlorite. This nature is in accordance with the mineralizing fluid that formed the inner alteration zone in the Nabarlek deposit. In conclusion, the vein

  19. Viscous property of dried clay

    Institute of Scientific and Technical Information of China (English)

    XU Li-sheng; LI Jian-zhong

    2006-01-01

    One dimensional and triaxial compression tests of air-dried and oven-dried Fujinomori clay and Pisa clay were carried out. Water content is less than 4.5 % and 1.0% for air-dried and oven-dried clay specimens, respectively. In all tests, axial strain rate was changed stepwise many times and drained creep tests were performed several times during monotonic loading at a constant strain rate. Global unloading (and also reloading in some tests) was applied during which creep loading tests were performed several times. Cyclic loading with small stress amplitude and several cycles was also performed to calculate the modulus of elasticity of the clay in tests. Local displacement transducer was used in triaxial compression test to increase measuring accuracy of axial strain. The results show that air-dried and oven-dried clay have noticeable viscous properties; during global unloading, creep deformation changes from positive to negative, i.e. there exist neutral points (zero creep deformation or no creep deformation point) in global unloading part of strain-stress curve; viscous property of Fujinomori clay decreases when water content decreases, i.e. viscous property of air-dried Fujinomori clay is more significant than that of oven-dried Fujinomori clay.

  20. Advances in characterization of the soil clay mineralogy using X-ray diffraction: from decomposition to profile fitting

    OpenAIRE

    2009-01-01

    International audience; Structural characterization of soil clay minerals often remains limited despite their key influence on soil properties. In soils, complex clay parageneses result from the coexistence of clay species with contrasting particle sizes and crystal-chemistry and from the profusion of mixed layers with variable compositions. The present study aimed at characterizing the mineralogy and crystal chemistry of the < 2 μm fraction along a profile typical of soils from Western Europ...

  1. Lead removal from aqueous solutions by a Tunisian smectitic clay.

    Science.gov (United States)

    Chaari, Islem; Fakhfakh, Emna; Chakroun, Salima; Bouzid, Jalel; Boujelben, Nesrine; Feki, Mongi; Rocha, Fernando; Jamoussi, Fakher

    2008-08-15

    The adsorption of Pb(2+) ions onto Tunisian smectite-rich clay in aqueous solution was studied in a batch system. Four samples of clay (AYD, AYDh, AYDs, AYDc) were used. The raw AYD clay was sampled in the Coniacian-Early Campanian of Jebel Aïdoudi in El Hamma area (South of Tunisia). AYDh and AYDs corresponds to AYD activated by 2.5 mol/l hydrochloric acid and 2.5 mol/l sulphuric acid, respectively. AYDc corresponds to AYD calcined at different temperatures (100, 200, 300, 400, 500 and 600 degrees C). The raw AYD clay was characterized by X-ray diffraction, chemical analysis, infrared spectroscopy and coupled DTA-TGA. Specific surface area of all the clay samples was determined from nitrogen adsorption isotherms. Preliminary adsorption tests showed that sulphuric acid and hydrochloric acid activation of raw AYD clay enhanced its adsorption capacity for Pb(2+) ions. However, the uptake of Pb(2+) by AYDs was very high compared to that by AYDh. This fact was attributed to the greater solubility of clay minerals in sulphuric acid compared to hydrochloric acid. Thermic activation of AYD clay reduced the Pb(2+) uptake as soon as calcination temperature reaches 200 degrees C. All these preliminary results were well correlated to the variation of the specific surface area of the clay samples. The ability of AYDs sample to remove Pb(2+) from aqueous solutions has been studied at different operating conditions: contact time, adsorbent amount, metal ion concentration and pH. Kinetic experiments showed that the sorption of lead ions on AYDs was very fast and the equilibrium was practically reached after only 20 min. The results revealed also that the adsorption of lead increases with an increase in the solution pH from 1 to 4.5 and then decreases, slightly between pH 4.5 and 6, and rapidly at pH 6.5 due to the precipitation of some Pb(2+) ions. The equilibrium data were analysed using Langmuir isotherm model. The maximum adsorption capacity (Q(0)) increased from 25 to 25

  2. Substantial iron sequestration during green-clay authigenesis in modern deep-sea sediments

    Science.gov (United States)

    Baldermann, A.; Warr, L. N.; Letofsky-Papst, I.; Mavromatis, V.

    2015-11-01

    In much of the global ocean, iron is a limiting nutrient for marine productivity. The formation of pyrite has been considered the most important sink of reactive iron in modern, organic-rich sediments. However, clay mineral transformations can also lead to long-term sequestration of iron during late diagenesis and in hydrothermal settings. Here we present evidence for substantial iron sequestration during the early diagenetic formation of ferruginous clay minerals, also called green-clay authigenesis, in the deep-sea environment of the Ivory Coast-Ghana Marginal Ridge. Using high-resolution electron microscopic methods and sequential sediment extraction techniques, we demonstrate that iron uptake by green-clay authigenesis can amount to 76 +/- 127 μmol Fe cm-2 kyr-1, which is on average six times higher than that of pyrite in suboxic subsurface sediments 5 m below the sea floor or shallower. Even at depths of 15 m below the sea floor or greater, rates of iron burial by green clay and pyrite are almost equal at ~80 μmol Fe cm-2 kyr-1. We conclude that green-clay formation significantly reduces the pore water inventory of dissolved iron in modern and ancient pelagic sediments, which challenges the long-standing conceptual view that clay mineral diagenesis is of little importance in current biogeochemical models of the marine iron cycle.

  3. Properties and organic activation of ocean clay in the East Pacific

    Institute of Scientific and Technical Information of China (English)

    Peiping Zhang; Xiaoguo Chi; Chunyan Tian; Baojun Wang; Huahua Lü; Xuefa Shi

    2006-01-01

    In order to make use of ocean clay reasonably and excavate its potential applications the properties of ocean clay in Chinese investigating area of the East Pacific have been tested with the chemical analysis, XRFS, ICP/MAS, granulometry and SSA, etc. The results show that the clay sediments of this area are rich in clay minerals, fine granularity, bigger SSA, bigger water absorbability and lower ion changing ability etc. To improve the adaptability of ocean clay and macromolecule materials, using the dry milling method with silane, aluminate, stearic acid coupling agents etc the properties of ocean clay are improved. The effect has been evaluated by testing the water absorbing of the modified ocean clay and their dispersing in paraffin liquid. The result is that KH550 is better than any other active reagents, and the best activation technics is that 1.5% (volume) of KH550 quantity, 20min of milling time. The DTA, XRD, SEM and IR analyses and SSA testing show that the organic activation can not change the mineral structure but can densify the structure of clay, and activation mechanism is chemical covered mainly and chemical combined secondly.

  4. Radionuclide interaction with clays in dilute and heavily compacted systems: a critical review.

    Science.gov (United States)

    Miller, Andrew W; Wang, Yifeng

    2012-02-21

    Given the unique properties of clays (i.e., low permeability and high ion sorption/exchange capacity), clays or clay formations have been proposed either as an engineered material or as a geologic medium for nuclear waste isolation and disposal. A credible evaluation of such disposal systems relies on the ability to predict the behavior of these materials under a wide range of thermal-hydrological-mechanical-chemical (THMc) conditions. Current model couplings between THM and chemical processes are simplistic and limited in scope. This review focuses on the uptake of radionuclides onto clay materials as controlled by mineral composition, structure, and texture (e.g., pore size distribution), and emphasizes the connections between sorption chemistry and mechanical compaction. Variable uptake behavior of an array of elements has been observed on various clays as a function of increasing compaction due to changes in pore size and structure, hydration energy, and overlapping electric double layers. The causes for this variability are divided between "internal" (based on the fundamental structure and composition of the clay minerals) and "external" (caused by a force external to the clay). New techniques need to be developed to exploit known variations in clay mineralogy to separate internal from external effects.

  5. Mineral resource of the month: vermiculite

    Science.gov (United States)

    Tanner, Arnold O.

    2014-01-01

    Vermiculite comprises a group of hydrated, laminar magnesium-aluminum-iron silicate minerals resembling mica. They are secondary minerals, typically altered biotite, iron-rich phlogopite or other micas or clay-like minerals that are themselves sometimes alteration products of amphibole, chlorite, olivine and pyroxene. Vermiculite deposits are associated with volcanic ultramafic rocks rich in magnesium silicate minerals, and flakes of the mineral range in color from black to shades of brown and yellow. The crystal structure of vermiculite contains water molecules, a property that is critical to its processing for common uses.

  6. The Interface Reaction between Pseudomonas putida and Soil Clay Minerals and Its Effect on the Biodegradation of Methyl Parathion%恶臭假单胞菌与土壤矿物的界面反应及其对甲基对硫磷降解影响

    Institute of Scientific and Technical Information of China (English)

    冯伟亮; 贺小敏; 沈敏; 张晓斌; 陈浩; 黄巧云

    2009-01-01

    Adsorption characteristics and metabolism curves of Pseudomonas putida on the surfaces of montmorillonite, kaolinite and goethite were investigated. Biodegradation kinetics of methyl parathion by Pseudomonas putida was also measured in the presence of various clay minerals. The binding strength of Pseudomonas putida on minerals followed the sequence of goethite > kaolinite > montmorillonite. The metabolism abilities of free cells were stronger than that of immobilized ones at a methyl parathion of 10 mg/L over the whole incubation period. However, the percent degradation of methyl parathion by immobilized cells was higher (within 9 h) and then gradually lower than by free ones at high pesticide concentrations (20~40 mg/L). Degradation capabilities of Pseudomonas putida sorbed on various minerals followed the sequence of montmorillonite > kaolinite > goethite. Montmorillonite presented a lower affinity for Pseudomonas putida, and it could enhance the bacterial activity and further stimulate the bioavailability of pesticide. However, goethite exhibited higher sorption capability for the bacterium, and it could display an inhibitory effect on the bacterial activitiy and hinder the substrate biodegradation.%研究了恶臭假单胞菌在蒙脱石、高岭石和针铁矿表面的吸附特征,探讨了细菌在不同粘粒矿物存在下的生长代谢活性,及对甲基对硫磷的降解动力学.结果表明, 三种矿物对细菌的吸附强度为针铁矿>高岭石>蒙脱石.当甲基对硫磷浓度较低时(10 mg/L), 游离菌的降解能力始终比固定菌强;在高浓度(20~40 mg/L)下, 固定菌对农药的降解能力起初(前9 h)高于游离菌, 随后渐渐低于游离菌.不同矿物固定的细菌, 其降解能力为蒙脱石>高岭石>针铁矿.蒙脱石对细菌的亲和力最弱, 但它对细菌的代谢活性有促进作用, 有利于农药的生物降解; 而针铁矿与细菌的结合强度最大, 细菌活性受到抑制, 不利于农药的降解.

  7. Magnetic properties of Jiaxian red clay sequences from northern Chinese Loess Plateau and its paleoclimatic significance

    Institute of Scientific and Technical Information of China (English)

    QIANG; Xiaoke; AN; Zhisheng; LI; Huamei; CHANG; Hong

    2005-01-01

    Detailed rock magnetism investigation of the Jiaxian red clay sequences indicated that there are common magnetic mineralogy properties in red clay and loess-paleosol sequences from the Chinese Loess Plateau as well as the marked properties of themselves, magnetic minerals mainly with magnetite, maghemite, hematite, and possibly limonite/goethite contributing to the magnetic behavior. Meanwhile, it is found that the strong paleosol in red clay sequences has a lower coercivity and higher content of ultra-fine ferrimagnetic grains than that of the weak paleosol, which is similar to loess and paleosol in upper Wucheng Loess sequences, and indicates that humid conditions and relatively strong pedogenesis play a significant role in the increase of ultra-fine magnetic minerals and transformation of the magnetic minerals. This suggests that, like Quaternary loess-paleosols, the change of characteristics of paleoclimatic conditions of the late Tertiary red clay deposits is fluctuant. In addition, the results of magnetic hysteresis properties show that the applied saturated field for samples from the Jiaxian red clay sequences is higher than that of the samples from eastern and southern Chinese Loess Plateau. It is obviously shown that there exist more hard magnetic minerals and relatively weak biochemical processes in the Jiaxian red clay sequences on northern Chinese Loess Plateau. We conclude that the paleoclimatic environment is different between northern and eastern/southern Chinese Loess Plateau, and it should be more arid in northern Chinese Loess Plateau.

  8. Evaluation of Used Fuel Disposition in Clay-Bearing Rock

    Energy Technology Data Exchange (ETDEWEB)

    Jove-Colon, Carlos F. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Weck, Philippe F. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hammond, Glenn Edward [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Kuhlman, Kristopher L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Zheng, Liange [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Rutqvist, Jonny [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Kim, Kunhwi [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Houseworth, James [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Caporuscio, Florie Andre [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Cheshire, Michael [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Palaich, Sarah [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Norskog, Katherine E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Zavarin, Mavrik [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Wolery, Thomas J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Jerden, James L. [Argonne National Lab. (ANL), Argonne, IL (United States); Copple, Jacqueline M. [Argonne National Lab. (ANL), Argonne, IL (United States); Cruse, Terry [Argonne National Lab. (ANL), Argonne, IL (United States); Ebert, William L. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2015-09-04

    Deep geological disposal of nuclear waste in clay/shale/argillaceous rock formations has received much consideration given its desirable attributes such as isolation properties (low permeability), geochemically reduced conditions, slow diffusion, sorbtive mineralogy, and geologically widespread (Jové Colón et al., 2014). There is a wealth of gained scientific expertise on the behavior of clay/shale/ argillaceous rock given its focus in international nuclear waste repository programs that includes underground research laboratories (URLs) in Switzerland, France, Belgium, and Japan. Jové Colón et al. (2014) have described some of these investigative efforts in clay rock ranging from site characterization to research on the engineered barrier system (EBS). Evaluations of disposal options that include nuclear waste disposition in clay/shale/argillaceous rock have determined that this host media can accommodate a wide range of waste types. R&D work within the Used Fuel Disposition Campaign (UFDC) assessing thermal effects and fluid-mineral interactions for the disposition of heat-generating waste have so far demonstrated the feasibility for the EBS and clay host rock to withstand high thermal loads. This report represents the continuation of disposal R&D efforts on the advancement and refinement of coupled Thermal-Hydrological-Mechanical-Chemical (THMC), hydrothermal experiments on clay interactions, used fuel degradation (source term), and thermodynamic modeling and database development. The development and implementation of a clay/shale/argillite reference case described in Jové Colón et al. (2014) for FY15 will be documented in another report (Mariner et al. 2015) – only a brief description will be given here. This clay reference case implementation is the result of integration efforts between the GDSA PA and disposal in argillite work packages. The assessment of sacrificial zones in the EBS is being addressed through experimental work along with 1D reactive

  9. Color measurement of methylene blue dye/clay mixtures and its application using economical methods

    Science.gov (United States)

    Milosevic, Maja; Kaludjerovic, Lazar; Logar, Mihovil

    2016-04-01

    Identifying the clay mineral components of clay materials by staining tests is rapid and simple, but their applicability is restricted because of the mutual interference of the common components of clay materials and difficulties in color determination. The change of color with concentration of the dye is related to the use of colorants as a field test for identifying clay minerals and has been improved over the years to assure the accuracy of the tests (Faust G. T., 1940). The problem of measurement and standardization of color may be solved by combination of colors observed in staining tests with prepared charts of color chips available in the Munsell Book of Color, published by Munsell Color Co. Under a particular set of illumination conditions, a human eye can achieve an approximate match between the color of the dyed clay sample and that of a standard color chip, even though they do have different spectral reflectance characteristics. Experiments were carried out with diffuse reflectance spectroscopy on selected clay samples (three montmorillonite, three kaolinite and one mix-layer clay samples) saturated with different concentration of methylene blue dye solution. Dominant wavelength and purity of the color was obtained on oriented dry samples and calculated by use of the I. C. I. (x, y) - diagram in the region of 400-700 nm (reflectance spectra) without MB and after saturation with different concentrations of MB solutions. Samples were carefully photographed in the natural light environment and processed with user friendly and easily accessible applications (Adobe color CC and ColorHexa encyclopedia) available for android phones or tablets. Obtained colors were compared with Munsell standard color chips, RGB and Hexa color standards. Changes in the color of clay samples in their interaction with different concentration of the applied dye together with application of economical methods can still be used as a rapid fieldwork test. Different types of clay

  10. Electron transfer and atom exchange between aqueous Fe(II) and structural Fe(III) in clays. Role in U and Hg(II) transformations

    Energy Technology Data Exchange (ETDEWEB)

    Scherer, Michelle [Univ. of Iowa, Iowa City, IA (United States)

    2016-08-31

    During this project, we investigated Fe electron transfer and atom exchange between aqueous Fe(II) and structural Fe(III) in clay minerals. We used selective chemical extractions, enriched Fe isotope tracer experiments, computational molecular modeling, and Mössbauer spectroscopy. Our findings indicate that structural Fe(III) in clay minerals is reduced by aqueous Fe(II) and that electron transfer occurs when Fe(II) is sorbed to either basal planes and edge OH-groups of clay mineral. Findings from highly enriched isotope experiments suggest that up to 30 % of the Fe atoms in the structure of some clay minerals exhanges with aqueous Fe(II). First principles calculations using a small polaron hopping approach suggest surprisingly fast electron mobility at room temperature in a nontronite clay mineral and are consistent with temperature dependent Mössbauer data Fast electron mobility suggests that electrons may be able to conduct through the mineral fast enough to enable exchange of Fe between the aqueous phase and clay mineral structure. over the time periods we observed. Our findings suggest that Fe in clay minerals is not as stable as previously thought.

  11. Fluoride retention by kaolin clay

    DEFF Research Database (Denmark)

    Kau, P. M. H.; Smith, D. W.; Binning, Philip John

    1997-01-01

    To evaluate the potential effectiveness of kaolin clay liners in storage of fluoride contaminated waste, an experimental study of the sorption and desorption behaviour of fluoride in kaolin clay was conducted. The degree of fluoride sorption by kaolin was found to depend on solution p......H and available fluoride concentration with equilibrium being achieved within 24 h. A site activation process involving the uptake of fluoride was also observed at the initial stages of sorption. This behaviour was attributed to a layer expansion process of the clay during sorption. The maximum fluoride sorption...

  12. Mineral resources

    Digital Repository Service at National Institute of Oceanography (India)

    Valsangkar, A.B.

    Marine minerals have been center of attraction to mankind since ancient times. The technological advances in the recent years show that the retrieval of underwater minerals from deep-sea can no longer be a dream. Marine minerals are terrigenous...

  13. Unearthing the Antibacterial Mechanism of Medicinal Clay: A Geochemical Approach to Combating Antibiotic Resistance

    Science.gov (United States)

    Morrison, Keith D.; Misra, Rajeev; Williams, Lynda B.

    2016-01-01

    Natural antibacterial clays, when hydrated and applied topically, kill human pathogens including antibiotic resistant strains proliferating worldwide. Only certain clays are bactericidal; those containing soluble reduced metals and expandable clay minerals that absorb cations, providing a capacity for extended metal release and production of toxic hydroxyl radicals. Here we show the critical antibacterial components are soluble Fe2+ and Al3+ that synergistically attack multiple cellular systems in pathogens normally growth-limited by Fe supply. This geochemical process is more effective than metal solutions alone and provides an alternative antibacterial strategy to traditional antibiotics. Advanced bioimaging methods and genetic show that Al3+ misfolds cell membrane proteins, while Fe2+ evokes membrane oxidation and enters the cytoplasm inflicting hydroxyl radical attack on intracellular proteins and DNA. The lethal reaction precipitates Fe3+-oxides as biomolecular damage proceeds. Discovery of this bactericidal mechanism demonstrated by natural clays should guide designs of new mineral-based antibacterial agents.

  14. Can clays ensure nuclear waste repositories?

    Science.gov (United States)

    Zaoui, A; Sekkal, W

    2015-03-06

    Research on argillite as a possible host rock for nuclear waste disposal is still an open subject since many issues need to be clarified. In the Underground Research Laboratories constructed for this purpose, a damaged zone around the excavation has been systematically observed and characterized by the appearance of micro-fissures. We analyse here -at nanoscale level- the calcite/clay assembly, the main constituents of argillite, under storage conditions and show the fragility of the montmorillonite with respect to calcite. Under anisotropic stress, we have observed a shear deformation of the assembly with the presence of broken bonds in the clay mineral, localised in the octahedral rather than the tetrahedral layers. The stress/strain curve leads to a failure strength point at 18.5 MPa. The obtained in-plane response of the assembly to perpendicular deformation is characterized by smaller perpendicular moduli Ez = 48.28 GPa compared to larger in-plane moduli Ex = 141.39 GPa and Ey = 134.02 GPa. Our calculations indicate the instability of the assembly without water molecules at the interface in addition to an important shear deformation.

  15. Mineral Composition and Weathering of Soils Derived from Xiashu Loess

    Institute of Scientific and Technical Information of China (English)

    DENGYOU-JUN; MAYI-JIE; 等

    1992-01-01

    Mineralogical,physical and chemical analyses of the soils derived from Xiashu loess were carried out.The primary minerals of these soils were found to be mainly composed of light minerals,such as quartz,feldspar and mica,with traces of heavy minerals.Clay minerals,more complicate in composition,were dominated by hydromica,accompanied by smectite,vermiculite,chlorite,kaolinite,2:1/1:1 randomly interstratified minerals and small amounts of quartz,goethite,lepidocrocite and hematite,Clay minerals were characterized by low crystallinity and fine particle size.In light of the quartz/feldspars ratio of the 0.01-0.05mm silt fraction,and the clay mineral composition,the freeness of iron oxide,and the silica/ sesquioxide and silica/ alumina ratios in <0.002mm clay fraction,it is concluded that the weathering intensity of these soils was lower than those of red soil and yellow earth,but higher than that of brown earth,and that the soil allitization,depotassication and hydroxylation of clay minerals increased from west to east and from north to south geographically.However,this general tendence did not coincide exactly with the gradual alteration of the geographic coordinates,and in some places,a reverse tendency also appeared,which could be attributed to the influence of some soil forming factors such as parent material and microtopography.

  16. Combined heavy mineral and biomarker analysis in silt: a novel approach for provenance studies (Indus Fan, IODP Expedition 355)

    Science.gov (United States)

    Andò, Sergio; Bratenkov, Sophia; Hahn, Annette; George, Simon; Clift, Peter D.; Garzanti, Eduardo

    2016-04-01

    A high-resolution mineralogical study of Indus Fan turbiditic sediments cored during IODP Expedition 355 (Arabian Sea Monsoon) in the Laxmi Basin was carried out to investigate and quantify the different compositional signatures encoded in the sand, silt, and clay fractions. The turbidite deposits recovered at IODP Sites U1456 and U1457 in sedimentological Unit II were chosen as the best candidate for such a study. The integrated dataset presented here was obtained by coupling traditional and innovative bulk-sediment to single-grain analytical techniques, including bulk petrography, heavy-mineral and biomarker analyses on the same samples. Reliable quantitative results even in the medium to fine silt classes, which represent the dominant sediment sizes encountered in the recovered cores, were obtained by point-counting under the microscope, assisted by Micro-Raman spectroscopy (Andò et al., 2011; 2014). Preliminary data from the studied turbidites document rich and diverse heavy mineral assemblages in both the sand and silty-sand fractions. Heavy-mineral concentrations, as well as the number of mineral species, reach a maximum in sand and tend to decrease with grain size, becoming minimal in the clay fraction. Conversely, the biomarker analysis is generally focused on the finer sediment fractions and clay, where better preservation of biomarker compounds are obtained. The two approaches are thus complementary. Because biomarkers tend to be depleted in sand and heavy minerals in clay, the medium silt fraction represents the most suitable size window for the joint application of these two techniques. Comparing heavy-mineral assemblages with biomarkers allows us to evaluate both continental and marine inputs in turbidites and the hemipelagic deposits of the Indus Fan. This new methodological approach plays a key role in the identification of the effects of climate change on marine depositional environments and helps us to differentiate among the diverse Himalayan

  17. SO2 gas adsorption by modified kaolin clays: influence of previous heating and time acid treatments.

    Science.gov (United States)

    Volzone, Cristina; Ortiga, Jose

    2011-10-01

    Modified kaolin clays were used as adsorbents for SO(2) gas adsorptions. The clays were heated up to 900 °C previous to acid treatments with 0.5 N sulfuric acid solutions at boiling temperature during different times up to 1440 min. Equilibrium adsorption at 25 °C and 0.1 MPa was carried out by using a volumetric apparatus. The samples were characterized by chemical analysis, X-ray diffraction and infrared analysis. The heating of the clays followed by acid treatment improved the adsorption capacity of the kaolin clays. The presence of amorphous silica and hydroxyl in the final products improved SO(2) adsorption capacity. Better properties for SO(2) adsorption were found in kaolin rich in not well ordered kaolinite clay mineral.

  18. Constitutive model for overconsolidated clays

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Based on the relationships between the Hvorslev envelope,the current yield sur-face and the reference yield surface,a new constitutive model for overconsolidated clays is proposed. It adopts the unified hardening parameter,to which the potential failure stress ratio and the characteristic state stress ratio are introduced. The model can describe many characteristics of overconsolidated clays,including stress-strain relationships,strain hardening and softening,stress dilatancy,and stress path dependency. Compared with the Cam-clay model,the model only re-quires one additional soil parameter which is the slope of the Hvorslev envelope. Comparisons with data from triaxial drained compression tests for Fujinomori clay show that the proposed model can rationally describe overconsolidated properties. In addition,the model is also used to predict the stress-strain relationship in the isotropic consolidation condition and the stress paths in the undrained triaxial compression tests.

  19. Colloidal gels: Clay goes patchy

    Science.gov (United States)

    Kegel, Willem K.; Lekkerkerker, Henk N. W.

    2011-01-01

    Empty liquids and equilibrium gels have so far been only theoretical possibilities, predicted for colloids with patchy interactions. But evidence of both has now been found in Laponite, a widely studied clay.

  20. An Evidence-Based Review on medicinal value of clays in traditional Persian medicine.

    Science.gov (United States)

    Hosseinkhani, Ayda; Montaseri, Hashem; Hosamo, Ammar; Zarshenas, Mohammad M

    2016-10-07

    The use of earths and clays for medical purposes dates back to antiquity. In recent years, there has been an increasing interest in researches on traditional remedies in the hope of discovering new drug. Iran is an ancient country with a medical backbone acquired from the experiences of ancient Persian scholars, who had made a great contribution to the development of the medical sciences. Many medical and pharmaceutical books by early Persian scientists still exist and may have the potential of leading researchers to new drug discoveries. Owing to the emergence of new and antimicrobial-resistant infections, present-day medicine has recently begun focusing on medicinal earths and clays especially as mineral antimicrobials. The current study is, therefore, aimed at gathering information regarding medicinal clays in traditional Persian medicine (TPM). Five main Persian materia medica with the key word 'tin' (clay) and current databases such as PubMed, Scopus, ScienceDirect, and Google Scholar were searched by key words 'white, green, red, maroon, violet, black, grey and pink clays' and 'pharmacological effects'. Twenty three clays were found in Persian manuscripts. Although their mineralogical compositions are unknown, different pharmacological properties have been attributed to these mineral medicaments. Clay's properties were widely used in medieval times for the treatment of infections to poisoning. They were also used in compound formulations, possibly for their pharmaceutical formulation modifying effects. Modern scientific proofs have also been found of many of the medicinal clays reported in Persian manuscripts. Although many of reported clays are still unknown, their characterization may lead to new medicinal developments. Novel analytical methods available today makes it possible to elucidate the chemical compositions of these minerals as parameters responsible for their medicinal effects.

  1. Clays in radioactive waste disposal

    OpenAIRE

    Delage, Pierre; Cui, Yu-Jun; Tang, Anh-Minh

    2010-01-01

    Clays and argillites are considered in some countries as possible host rocks for nuclear waste disposal at great depth. The use of compacted swelling clays as engineered barriers is also considered within the framework of the multi-barrier concept. In relation to these concepts, various research programs have been conducted to assess the thermo-hydro-mechanical properties of radioactive waste disposal at great depth. After introducing the concepts of waste isolation developed in Belgium, Fran...

  2. What makes a natural clay antibacterial?

    Science.gov (United States)

    Williams, Lynda B.; Metge, David W.; Eberl, Dennis D.; Harvey, Ronald W.; Turner, Amanda G.; Prapaipong, Panjai; Port-Peterson, Amisha T.

    2011-01-01

    Natural clays have been used in ancient and modern medicine, but the mechanism(s) that make certain clays lethal against bacterial pathogens has not been identified. We have compared the depositional environments, mineralogies, and chemistries of clays that exhibit antibacterial effects on a broad spectrum of human pathogens including antibiotic resistant strains. Natural antibacterial clays contain nanoscale (2+ solubility.

  3. Clay mineralogy, organic carbon burial, and redox evolution in Proterozoic oceans

    Science.gov (United States)

    Tosca, Nicholas J.; Johnston, David T.; Mushegian, Alexandra; Rothman, Daniel H.; Summons, Roger E.; Knoll, Andrew H.

    2010-03-01

    Clay minerals formed through chemical weathering have long been implicated in the burial of organic matter (OM), but because diagenesis and metamorphism commonly obscure the signature of weathering-derived clays in Precambrian rocks, clay mineralogy and its role in OM burial through much of geologic time remains incompletely understood. Here we have analyzed the mineralogy, geochemistry and total organic carbon (TOC) of organic rich shales deposited in late Archean to early Cambrian sedimentary basins. Across all samples we have quantified the contribution of 1 M and 1 Md illite polytypes, clay minerals formed by diagenetic transformation of smectite and/or kaolinite-rich weathering products. This mineralogical signal, together with corrected paleo-weathering indices, indicates that late Archean and Mesoproterozoic samples were moderately to intensely weathered. However, in late Neoproterozoic basins, 2 M1 illite/mica dominates clay mineralogy and paleo-weathering indices sharply decrease, consistent with an influx of chemically immature and relatively unweathered sediment. A late Neoproterozoic switch to micaceous clays is inconsistent with hypotheses for oxygen history that require an increased flux of weathering-derived clays (i.e., smectite or kaolinite) across the Precambrian-Cambrian boundary. Compared to previous studies, our XRD data display the same variation in Schultz Ratio across the late Neoproterozoic, but we show the cause to be micaceous clay and not pedogenic clay; paleo-weathering signals cannot be recovered from bulk mineralogy without this distinction. We find little evidence to support a link between these mineralogical variations and organic carbon in our samples and conclude that modal clay mineralogy cannot by itself explain an Ediacaran increase in atmospheric oxygen driven by enhanced OM burial.

  4. Wave liquefaction in soils with clay content

    DEFF Research Database (Denmark)

    Kirca, Özgür; Sumer, B. Mutlu; Fredsøe, Jørgen

    2012-01-01

    The paper presents the results of an experimental study of the influence of clay content (in silt-clay and sand-clay mixtures) on liquefaction beneath progressive waves. The experiments showed that the influence of clay content is very significant. Susceptibility of silt to liquefaction...... is increased with increasing clay content, up to 30%, beyond which the mixture of silt and clay is not liquefied. Sand may become prone to liquefaction with the introduction of clay, contrary to the general perception that this type of sediment is normally liquefaction resistant under waves....

  5. Simulation of flash dehydroxylation of clay particle using gPROMS

    DEFF Research Database (Denmark)

    Gebremariam, Abraham Teklay; Bøjer, Martin; Adelsward, Anicka

    2014-01-01

    The use of SCMs (supplementary cementitious materials) to replace part of the clinker in cement industry is gaining an increasing interest in order to reduce the CO2 footprint. The abundantly available clay minerals are potential sources of SCMs. Thermal treatment of kaolinite clay under moderate...... presents the development of a numerical model for the simulation of dehydroxylation of kaolinite clay using gPROMS (general PROcess Modeling System). Accordingly, a 1D dehydroxylation model is used to examine the thermal transformation of kaolinite into different phases. This model is used to predict...

  6. Aggregation and stability of anisotropic charged clay colloids in aqueous medium in the presence of salt.

    Science.gov (United States)

    Ali, Samim; Bandyopadhyay, Ranjini

    2016-01-01

    Na-montmorillonite nanoclay is a colloid of layered mineral silicate. When dispersed in water, this mineral swells on absorption of water and exfoliates into platelets with electric double layers on their surfaces. Even at low particle concentration, the aqueous dispersion can exhibit a spontaneous ergodicity breaking phase transition from a free flowing liquid to nonequilibrium, kinetically arrested and disordered states such as gels and glasses. In an earlier publication [Applied Clay Science, 2015, 114, 8592], we showed that the stability of clay gels can be enhanced by adding a salt later to the clay dispersion prepared in deionized water, rather than by adding the clay mineral to a previously mixed salt solution. Here, we directly track the collapsing interface of sedimenting clay gels using an optical method and show that adding salt after dispersing the clay mineral does indeed result in more stable gels even in very dilute dispersions. These weak gels are seen to exhibit a transient collapse after a finite delay time, a phenomenon observed previously in depletion gels. The velocity of the collapse oscillates with the age of the sample. However, the average velocity of collapse increases with sample age up to a peak value before decreasing at higher ages. With increasing salt concentration, the delay time for transient collapse decreases, while the peak value of the collapsing velocity increases. Using ultrasound attenuation spectroscopy, rheometry and cryogenic scanning electron microscopy, we confirm that morphological changes of the gel network assembly, facilitated by thermal fluctuations, lead to the observed collapse phenomenon. Since clay minerals are used extensively in polymer nanocomposites, as rheological modifiers, stabilizers and gas absorbents, we believe that the results reported in this work are extremely useful for several practical applications and also for understanding geophysical phenomena such as the formation and stability of quicksand

  7. 81 FR 31234 - NESHAP for Brick and Structural Clay Products Manufacturing; and NESHAP for Clay Ceramics...

    Science.gov (United States)

    2016-05-18

    ... AGENCY NESHAP for Brick and Structural Clay Products Manufacturing; and NESHAP for Clay Ceramics... Brick and Structural Clay Products (BSCP) Manufacturing and the final NESHAP for Clay Ceramics... No. EPA-HQ-OAR-2013-0290 for Clay Ceramics Manufacturing. All documents in the dockets are listed...

  8. Radiocesium sorption in relation to clay mineralogy of paddy soils in Fukushima, Japan

    Energy Technology Data Exchange (ETDEWEB)

    Nakao, Atsushi, E-mail: na_4_ka_triplochiton@kpu.ac.jp [Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Hangi-cho 1-5, Shimogamo, Sakyo-ku, Kyoto 606-8522 (Japan); Ogasawara, Sho [Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Hangi-cho 1-5, Shimogamo, Sakyo-ku, Kyoto 606-8522 (Japan); Sano, Oki; Ito, Toyoaki [Field Science Center, Graduate School of Agricultural Science, Tohoku University, Naruko-Onsen 232-3, Osaki, Miyagi 989-6711 (Japan); Yanai, Junta [Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Hangi-cho 1-5, Shimogamo, Sakyo-ku, Kyoto 606-8522 (Japan)

    2014-01-01

    Relationships between Radiocesium Interception Potential (RIP) and mineralogical characteristics of the clay fraction isolated from 97 paddy soils (Hama-dori, n = 25; Naka-dori, n = 36; Aizu, n = 36) in Fukushima Prefecture, Japan were investigated to clarify the mineralogical factors controlling the {sup 137}Cs retention ability of soils (half-life 30.1 y). Of all the fission products released by the Fukushima accident, {sup 137}Cs is the most important long-term contributor to the environmental contamination. The RIP, a quantitative index of the {sup 137}Cs retention ability, was determined for the soil clays. The composition of clay minerals in the soil clays was estimated from peak areas obtained using X-ray diffraction (XRD) analyses. The predominant clay mineral was smectite in soils from Hama-dori and Aizu, while this was variable for those from Naka-dori. Native K content of the soil clays was found to be an indicator of the amount of micaceous minerals. The average RIP for the 97 soil clays was 7.8 mol kg{sup −1}, and ranged from 2.4 mol kg{sup −1} to 19.4 mol kg{sup −1}. The RIP was significantly and positively correlated with native K content for each of the geographical regions, Hama-dori (r = 0.76, p < 0.001), Naka-dori (r = 0.43, p < 0.05), and Aizu (r = 0.76, P < 0.001), while it was not related to the relative abundance of smectite. The linear relationship between RIP and native K content not only indicate a large contribution of micaceous minerals to the {sup 137}Cs retention ability of the soil clays, but also could be used to predict the {sup 137}Cs retention ability of soil clays for other paddy fields in Fukushima and other areas. - Highlights: • RIP was measured for 97 paddy soils from Fukushima to assess {sup 137}Cs retention ability. • The dominant clay mineral was smectite, but this did not control RIP. • RIP was positively correlated with native K content. • Micaceous minerals were found to control the {sup 137}Cs retention

  9. U.S. Geological Survey Mineral Resources Program—Mineral resource science supporting informed decisionmaking

    Science.gov (United States)

    Wilkins, Aleeza M.; Doebrich, Jeff L.

    2016-09-19

    The USGS Mineral Resources Program (MRP) delivers unbiased science and information to increase understanding of mineral resource potential, production, and consumption, and how mineral resources interact with the environment. The MRP is the Federal Government’s sole source for this mineral resource science and information. Program goals are to (1) increase understanding of mineral resource formation, (2) provide mineral resource inventories and assessments, (3) broaden knowledge of the effects of mineral resources on the environment and society, and (4) provide analysis on the availability and reliability of mineral supplies.

  10. How mobile are sorbed cations in clays and clay rocks?

    Science.gov (United States)

    Gimmi, T; Kosakowski, G

    2011-02-15

    Diffusion of cations and other contaminants through clays is of central interest, because clays and clay rocks are widely considered as barrier materials for waste disposal sites. An intriguing experimental observation has been made in this context: Often, the diffusive flux of cations at trace concentrations is much larger and the retardation smaller than expected based on their sorption coefficients. So-called surface diffusion of sorbed cations has been invoked to explain the observations but remains a controversial issue. Moreover, the corresponding surface diffusion coefficients are largely unknown. Here we show that, by an appropriate scaling, published diffusion data covering a broad range of cations, clays, and chemical conditions can all be modeled satisfactorily by a surface diffusion model. The average mobility of sorbed cations seems to be primarily an intrinsic property of each cation that follows inversely its sorption affinity. With these surface mobilities, cation diffusion coefficients can now be estimated from those of water tracers. In pure clays at low salinities, surface diffusion can reduce the cation retardation by a factor of more than 1000.

  11. Cryptozoology Society

    Science.gov (United States)

    Richman, Barbara T.

    Reports of Loch Ness monsters, Bigfoot, and the Yeti spring u p from time to time, sparking scientific controversy about the veracity of these observations. Now an organization has been established to help cull, analyze, and disseminate information on the alleged creatures. The International Society of Cryptozoology, formed at a January meeting at the U.S. National Museum of Natural History of the Smithsonian Institution, will serve as the focal point for the investigation, analysis, publication, and discussion of animals of unexpected form or size or of unexpected occurrences in time or space.

  12. The nanophase iron mineral(s) in Mars soil

    Science.gov (United States)

    Banin, A.; Ben-Shlomo, T.; Margulies, L.; Blake, D. F.; Mancinelli, R. L.; Gehring, A. U.

    1993-01-01

    A series of surface-modified clays containing nanophase (np) iron oxide/oxyhydroxides of extremely small particle sizes, with total iron contents as high as found in Mars soil, were prepared by iron deposition on the clay surface from ferrous chloride solution. Comprehensive studies of the iron mineralogy in these "Mars-soil analogs" were conducted using chemical extractions, solubility analyses, pH and redox, x ray and electron diffractometry, electron microscopic imaging, specific surface area and particle size determinations, differential thermal analyses, magnetic properties characterization, spectral reflectance, and Viking biology simulation experiments. The clay matrix and the procedure used for synthesis produced nanophase iron oxides containing a certain proportion of divalent iron, which slowly converts to more stable, fully oxidized iron minerals. The clay acted as an effective matrix, both chemically and sterically, preventing the major part of the synthesized iron oxides from ripening, i.e., growing and developing larger crystals. The precipitated iron oxides appear as isodiametric or slightly elongated particles in the size range 1-10 nm, having large specific surface area. The noncrystalline nature of the iron compounds precipitated on the surface of the clay was verified by their complete extractability in oxalate. Lepidocrocite (gamma-FeOOH) was detected by selected area electron diffraction. It is formed from a double iron Fe(II)/Fe(III) hydroxy mineral such as "green rust," or ferrosic hydroxide. Magnetic measurements suggested that lepidocrocite converted to the more stable maghemite (gamma-Fe2O3) by mild heat treatment and then to nanophase hematite (alpha-Fe2O3) by extensive heat treatment. After mild heating, the iron-enriched clay became slightly magnetic, to the extent that it adheres to a hand-held magnet, as was observed with Mars soil. The chemical reactivity of the iron-enriched clays strongly resembles, and offers a plausible mechanism

  13. Adsorption capacity of methylene blue, an organic pollutant, by montmorillonite clay

    KAUST Repository

    Feddal, I.

    2013-11-19

    The isotherms and kinetics of the adsorption of a cationic dye in aqueous solution, methylene blue, on a local Algerian montmorillonite clay mineral (raw, sodium and thermally activated at 300 and 500°C) were determined experimentally. Various parameters influencing the adsorption were optimized, mainly solid-liquid contact time, mass of adsorbent, initial concentration of dye, pH of the solution and temperature. Results showed that the adsorption kinetics were fast: 30 min for the raw clay mineral, and 20 min for sodium clay mineral (SC) and thermally activated at 300°C, whereas with the clay mineral calcined at 500°C, the equilibrium was reached after 150 min only. The maximum adsorption capacity was reached at pH 6.6. Results deducted from the adsorption isotherms also showed that the retention follows the Langmuir model. In addition, it was found that the kinetics were in the order of 2 (K = 2.457 × 106 g/mg.h) for sodium clay and were limited by an intra-particle diffusion. SC was found to be a better adsorbent to remove methylene blue from industrial wastewater. © 2013 Balaban Desalination Publications. All rights reserved.

  14. Breakdown of Clays by Ectomycorrhizal Fungi Through Changes in Oxidation State of Iron

    Science.gov (United States)

    Arocena, J. M.; Velde, B.

    2012-04-01

    Organisms are known to play a significant role in the transformation of clay minerals in soils. In our earlier work on canola, barley and alfalfa, we reported that Glomus, an arbuscular mycorrhizae, selectively transformed biotite into 2:1 expanding clays through the oxidation of Fe (II) in biotite to Fe(III). In this presentation, we will share similar results on clay transformations mediated by ectomycorrhizal fungi colonizing the roots of coniferous trees. Clay samples were isolated from rhizosphere soils of sub-alpine fir (Abies lasiocarpa (Hook.) Nutt.) in northern British Columbia (Canada). Chemical and mineralogical properties of these soils had been reported in our earlier paper. In this study, we subjected the clay samples to iron X-ray Absorption Near Edge Spectroscopy (Fe-XANES) at the Canadian Light Source synchrotron facility in Saskatoon (Canada). Our initial results showed relatively higher amounts of Fe (III) than Fe(II) in clays collected from rhizosphere of Piloderma (an ectomycorrhizal fungus) compared to soils influenced by non-Piloderma species and Control (non-rhizosphere soil). Coupled with the results of X-ray diffraction (XRD) analysis, there seems to be a positive relationship between the relative amounts of Fe(III) and the 2:1 expanding clays. This relationship is consistent with our results on agricultural plants in laboratory experiments on biotites where we suggested that oxidation of Fe(II) to Fe(III) results in the formation of 2:1 expanding clays. In a related data set on chlorite alteration we observed that after dithionite-citrate-bicarbonate (DCB) treatment, the d-spacing of a slight portion of chloritic expanding clays shifted to higher angles indicating decreased d-spacing towards micaceous clays. The reductive process initiated through the action of the DCB treatment seems to indicate the collapsed of expandable clays upon the reduction of Fe(III) to Fe(II). Initial results from the Fe-XANES and XRD analysis of DCB

  15. Acidities of confined water in interlayer space of clay minerals

    NARCIS (Netherlands)

    Liu, X.; Lu, X.; Wang, R.; Meijer, E.J.; Zhou, H.

    2011-01-01

    The acid chemistry of confined waters in smectite interlayers have been investigated with first principles molecular dynamics (FPMD) simulations. Aiming at a systematic picture, we establish the model systems to take account of the three possible controlling factors: layer charge densities (0 e, 0.5

  16. Sorption of the herbicide aminocyclopyrachlor by cation modified clay minerals

    Science.gov (United States)

    Aminocyclopyrachlor is a newly registered herbicide for the control of broadleaf weeds, grasses, vines and woody species in non-crops, turf, sod farms, and residential areas. At typical soil pH levels, aminocyclopyrachlor is in the anionic form. Anionic pesticides are generally weakly retained by mo...

  17. Effects of clay dispersion on aquifer storage and recovery in coastal aquifers

    Science.gov (United States)

    Konikow, L.F.; August, L.L.; Voss, C.I.

    2001-01-01

    Cyclic injection, storage, and withdrawal of freshwater in brackish aquifers is a form of aquifer storage and recovery (ASR) that can beneficially supplement water supplies in coastal areas. A 1970s field experiment in Norfolk, Virginia, showed that clay dispersion in the unconsolidated sedimentary aquifer occurred because of cation exchange on clay minerals as freshwater displaced brackish formation water. Migration of interstitial clay particles clogged pores, reduced permeability, and decreased recovery efficiency, but a calcium preflush was found to reduce clay dispersion and lead to a higher recovery efficiency. Column experiments were performed in this study to quantify the relations between permeability changes and clay mineralogy, clay content, and initial water salinity. The results of these experiments indicate that dispersion of montmorillonite clay is a primary contributor to formation damage. The reduction in permeability by clay dispersion may be expressed as a linear function of chloride content. Incorporating these simple functions into a radial, cross-sectional, variable-density, ground-water flow and transport model yielded a satisfactory simulation of the Norfolk field test - and represented an improvement over the model that ignored changes in permeability. This type of model offers a useful planning and design tool for ASR operations in coastal clastic aquifer systems.

  18. Charm of Purple Clay A private museum in Wuxi is devoted to purple-clay art

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Purple-clay art pieces will be on display in a museum opening soon in Wuxi, Jiangsu Province. The museum, named Shuaiyuan Purple Clay Museum, is part of the Shuaiyuan Purple Clay Art Exhibition Center

  19. Pillared clays : preparation and characterization of clay minerals and aluminum-based pillaring agents

    NARCIS (Netherlands)

    Kloprogge, J.T.

    1992-01-01

    After an extensive introductory chapter (Chapter I), in which the background and the aim of the research is dealt with, the hydrothermal synthesis and the characterization of Na-beidellite is discussed in Chapter II and III. The conditions of temperature, water pressure, and sodium activity under wh

  20. Searching for reciclability of modified clays for an environmental application

    Science.gov (United States)

    Del Hoyo Martínez, Carmen; Solange Lozano García, Marina; Sánchez Escribano, Vicente; Antequera, Jorge

    2014-05-01

    Thanks to the development of the science and the technology of the nourishment in the last 50 years, there have revealed itself several new substances that can fulfill beneficial functions in the food, and these substances, named food additives, are today within reach of all. The food additives recover a very important role in the complex nourishing supply. The additives fulfill several useful functions in the food, which often we give for sat. Nevertheless the widespread use of food additives in the food production also influences the public health. The food industries, which are very important for the economy, spill residues proved from its activity that they have to be controlled to evaluate the environmental impact and to offer the necessary information about the quantitative evaluation of the chemical risk of the use of food additives for the public health. The clay materials have led to numerous applications in the field of public health (del Hoyo, 2007; Volzone, 2007) having been demonstrated its effectiveness as adsorbents of all contaminants. Some biodegradable materials are used for for adsorption of chemical contaminants: lignins (Valderrabano et al., 2008) and also clays and clay minerals, whose colloidal properties, ease of generating structural changes, abundance in nature, and low cost make them very suitable for this kind of applications. Among the strategies used at present to preserve the quality of the water and this way to diminish the environmental risk that supposes the chemical pollution, stands out the use of adsorbents of under cost, already they are natural or modified, to immobilize these compounds and to avoid the pollution of the water with the consequent reduction of environmental and economic costs. We have studied the adsorption of several contaminants related to the food industry by natural or modified clays, searching their interaction mechanisms and the possible recycling of these materials for environmental purposes and

  1. The influence of clay additives in Portland cement on the compressive strength of the cement stone

    Directory of Open Access Journals (Sweden)

    A.R. Gaifullin

    2015-11-01

    Full Text Available The introduction of mineral additives to binders, especially to Portland cement, is one of the promising trends for solving the resource and energy saving problems, as well as problems of environmental protection during production and application. Expanding the supplementary cementitious materials resource base can be achieved through the use of natural pozzolans and thermally activated polymineral clays(commonly known as glinites in Russia. One type of glinite is metakaolin, which is obtained by calcination of kaolin clays. Metakaolin is widely and effectively used as a pozzolanic additive due to its beneficial effect on the physical and mechanical properties of Portland cement-based materials. The obstacle to its wide production and use are the limited deposits of pure kaolin clays in many countries, including the Russian Federation. In this respect, the studies of pozzolanic activity of the most common mineral clays and their use in some countries have significantly advanced. Similar studies were widely performed in the 1940s in USSR. It seems reasonable to renew this trend to provide a scientific base for the production of local pozzolans made of clays commonly used in different regions. Comparative studies of the effect of 5 clays differing in mineral and chemical composition, calcination temperature and specific surface area, and high-quality metakaolin, on the strength of hardened Portland cement paste have been performed. It has been established that introducing 5…10 % of composite clays calcined at 400…8000 C° and milled to a specific surface area of 290…800 m2/kg into Portland cement enhanced the strength of the hardened cement paste considerably better than the introduction of metakaolin with a specific surface area of 1200 m2/kg. The findings of the study suggest that many kinds of commonly used polymineral clays have a specific calcination temperature and dispersity, which results in a higher pozzolanic activity compared with

  2. Industrial mineral powder production in China

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The recent annual output of major industrial mineral powders in the mainland of China has been more than 100 million t, accompanied by active development of such supporting technology as comminution, classification, separation/purification, and surface modification. In particular, the present paper reviews technologies for preparing ultra-fine particles involving dry and wet processing, modification and composition, calcination of kaolin clay, and processing of spherical/acerous industrial minerals.

  3. 80 FR 75817 - NESHAP for Brick and Structural Clay Products Manufacturing; and NESHAP for Clay Ceramics...

    Science.gov (United States)

    2015-12-04

    ... NESHAP for Clay Ceramics Manufacturing: Correction AGENCY: Environmental Protection Agency (EPA). ACTION...; and NESHAP for Clay Ceramics Manufacturing. These amendments make two technical corrections to...

  4. Geochemical effects of electro-osmosis in clays

    KAUST Repository

    Loch, J. P. Gustav

    2010-02-13

    Geochemical effects of electro-osmosis in bentonite clay are studied in the laboratory, where a 6 mm thick bentonite layer is subjected to direct current. Acidification and alkalization near anode and cathode are expected, possibly causing mineral deterioration, ion mobilization and precipitation of new solids. Afterwards the clay is analysed by XRF and anolyte and catholyte are analysed by ICP-MS. In addition, as a preliminary experiment treated bentonite is analysed by high resolution μ-XRF. Electro-osmotic flow is observed. Due to its carbonate content the bentonite is pH-buffering. Alkalization in the catholyte is substantial. Ca, Na and Sr are significantly removed from the clay and accumulate in the catholyte. Recovery in the catholyte accounts for a small fraction of the element-loss from the clay. The rest will have precipitated in undetected solid phases. μ-XRF indicates the loss of Ca-content throughout the bentonite layer. © The Author(s) 2010.

  5. Speciation of neptunium during sorption and diffusion in natural clay

    Science.gov (United States)

    Reich, T.; Amayri, S.; Bӧrner, P. J. B.; Drebert, J.; Frӧhlich, D. R.; Grolimund, D.; Kaplan, U.

    2016-05-01

    In argillaceous rocks, which are considered as a potential host rock for nuclear waste repositories, sorption and diffusion processes govern the migration behaviour of actinides like neptunium. For the safety analysis of such a repository, a molecular-level understanding of the transport and retardation phenomena of radioactive contaminants in the host rock is mandatory. The speciation of Np during sorption and diffusion in Opalinus Clay was studied at near neutral pH using a combination of spatially resolved synchrotron radiation techniques. During the sorption and diffusion experiments, the interaction of 8 μM Np(V) solutions with the clay lead to the formation of spots at the clay-water interface with increased Np concentrations as determined by μ-XRF. Several of these spots are correlated with areas of increased Fe concentration. Np L3-edge μ-XANES spectra revealed that up to 85% of the initial Np(V) was reduced to Np(IV). Pyrite could be identified by μ-XRD as a redox-active mineral phase responsible for the formation of Np(IV). The analysis of the diffusion profile within the clay matrix after an in-diffusion experiment for two months showed that Np(V) is progressively reduced with diffusion distance, i.e. Np(IV) amounted to ≈12% and ≈26% at 30 μm and 525 μm, respectively.

  6. Aflatoxin Toxicity Reduction in Feed by Enhanced Binding to Surface-Modified Clay Additives

    Directory of Open Access Journals (Sweden)

    Richard E. Zartman

    2011-06-01

    Full Text Available Animal feeding studies have demonstrated that clay additives, such as bentonites, can bind aflatoxins in ingested feed and reduce or eliminate the toxicity. Bentonite deposits are found throughout the world and mostly consist of expandable smectite minerals, such as montmorillonite. The surfaces of smectite minerals can be treated with organic compounds to create surface-modified clays that more readily bind some contaminants than the untreated clay. Montmorillonites treated with organic cations, such as hexadecyltrimethylammonium (HDTMA and phenyltrimethylammonium (PTMA, more effectively remove organic contaminants, such as benzene and toluene, from water than untreated clay. Similarly, montmorillonite treated with PTMA (Kd = 24,100 retained more aflatoxin B1 (AfB1 from aqueous corn flour than untreated montmorillonite (Kd = 944. Feed additives that reduced aflatoxin toxicity in animal feeding studies adsorbed more AfB1 from aqueous corn flour than feed additives that were less effective. The organic cations HDTMA and PTMA are considered toxic and would not be suitable for clay additives used in feed or food, but other non-toxic or nutrient compounds can be used to prepare surface-modified clays. Montmorillonite (SWy treated with choline (Kd = 13,800 and carnitine (Kd = 3960 adsorbed much more AfB1 from aqueous corn flour than the untreated clay (Kd = 944. A choline-treated clay prepared from a reduced-charge, high-charge montmorillonite (Kd = 20,100 adsorbed more AfB1 than the choline-treated high-charge montmorillonite (Kd = 1340 or the untreated montmorillonite (Kd = 293. Surface-modified clay additives prepared using low-charge smectites and nutrient or non-toxic organic compounds might be used to more effectively bind aflatoxins in contaminated feed or food and prevent toxicity.

  7. Can corn plants inoculated with arbuscular mycorrhiza fungi affect soil clay assemblage?

    Science.gov (United States)

    Adamo, P.; Cozzolino, V.; Di Meo, V.; Velde, B.

    2012-04-01

    Plants can extract K from exchangeable and non-exchangeable sites in the soil clay mineral structures. The latter, known as fixed K, is usually seen as an illite layer, i.e. an anhydrous K layer that forms a 1.0 nm structural layer unit as seen by X-ray diffraction. Nutrient availability can be enhanced in the root zone by arbuscular mycorrhiza fungi. In this study, the effects of non-inoculated and Glomus intraradices inoculated corn plant growth under different experimental conditions on soil K-bearing clay minerals were identified. The soil, a Vertic Xerofluvent, was planted in corn in a 2008-2010 randomized field experiment. Bulk and rhizosphere soil sampling was carried out from May to September 2010 from fertilized plots (N200P90K160 and N200P0K160) with and without plants. According to XRD analysis, three major K-bearing minerals were present in soil: smectite-rich mixed layer mineral, illite-rich mixed layer mineral and illite. Results at 40DAS indicate extraction of K from clay minerals by plant uptake, whereas at 130DAS much of the nutrient seems to be returned to the soil. There is an apparent difference between bulk and rhizophere clays. The XRD patterns are not unequivocally affected by Glomus inoculation. There are observable changes in clay mineralogy in fallow unfertilized compared with fertilized soil. In the studied soil, the illite rich mixed-layer minerals seem to be the source of K absorbed by plants, while illite acts as sink of K released from the plant-microorganisms system at the end of the growing season and as source for the following crop.

  8. Clay alteration and gold deposition in the genesis and blue star deposits, Eureka County, Nevada

    Science.gov (United States)

    Drews-Armitage, S. P.; Romberger, S.B.; Whitney, C.G.

    1996-01-01

    The Genesis and Blue Star sedimentary rock-hosted gold deposits occur within the 40-mile-long Carlin trend and are located in Eureka County, Nevada. The deposits are hosted within the Devonian calcareous Popovich Formation, the siliciclastic Rodeo Creek unit and the siliciclastic Vinini Formation. The host rocks have undergone contact metamorphism, decalcification, silicification, argillization, and supergene oxidation. Detailed characterization of the alteration patterns, mineralogy, modes of occurrence, and associated geochemistry of clay minerals resulted in the following classifications: least altered rocks, found distal to the orebody, consisting of both metamorphosed and unmetamorphosed host rock that has not been completely decalcified; and altered rocks, found proximal to the orebody that have been decalcified. Altered rocks are classified further into the following groups based on clay mineral content: silicic, 1 to 10 percent clay; silicicargillic, 10 to 35 percent clay; and argillic, 35 to 80 percent clay. Clay species identified are 1M illite, 2M1 illite, kaolinite, halloysite, and dioctahedral smectite. An early hydrothermal event resulted in the precipitation of euhedral kaolinite and at least one generation of silica. This event occurred contemporaneously with decalcification which increased rock permeability and porosity. A second clay alteration event resulted in the precipitation of hydrothermal 1M illite which replaced hydrothermal kaolinite and is associated with gold deposition. Silver and silica deposition is also associated with this phase of hydrothermal alteration. Hydrothermal alteration was followed by supergene alteration which resulted in the formation of supergene kaolinite, halloysite, and smectite as well as the oxidation of iron-bearing minerals. Supergene clays are concentrated along faults, dike margins, and within rocks containing carbonate. Gold mineralization is not associated with supergene clay minerals within the Genesis and

  9. Clay Mineralogy of Shallow Core Sediments of Lake Acigöl, Denizli, Turkey

    Science.gov (United States)

    Budakoglu, Murat; Karaman, Muhittin; Geredeli, Serpil; Unal, Hatice; Abdelnasser, Amr; Kiran Yildirim, Demet

    2014-05-01

    Lake Acıgöl is a hypersaline and active industrial salt production lake located in Denizli, Turkey. Lake Acıgöl has been investigated to elucidate the distribution clay minerals under the saline conditions of the lake and carbonate and ophiolitic rocks controlled lake basin. The lake is very shallow and generally characterized by an un-stratified and whole oxygenated water table. Determination clay minerals in the bulk samples via XRD method was not possible due to the their small amount. Therefore, the sequential clay enrichment procedure applied to the bulk samples such as sample dispersion, removal of soluble salts and ions, and particle-size fractionation. The XRD analyses of normal, glycolated and heat-treated shallow core samples show that the dominant clay minerals in the samples to be illite, including the swelling montmorillonite and kaolinite minerals are encountered less frequently. Glauberite, Blodite, Dansite and Nickelblodite have been also identified as soda minerals by XRD studies.

  10. Geopolymers Based on Phosphoric Acid and Illito-Kaolinitic Clay

    Directory of Open Access Journals (Sweden)

    S. Louati

    2016-01-01

    Full Text Available New three-dimensional geopolymer materials based on illito-kaolinitic clay and phosphoric acid were synthesized. The effect of Si/P molar ratio on the geopolymers properties was studied. Raw, calcined clay, and geopolymers structures were investigated using XRD, IR spectroscopy, and SEM. The phosphoric acid-based geopolymers mechanical properties were evaluated by measuring the compressive strength. The Si/P molar ratio was found to increase with the increase of the compressive strength of the obtained geopolymers, which attained a maximum value at Si/P equal to 2.75. Beyond this ratio, the mechanical strength decreases. The XRD patterns of these geopolymers samples have proven that when the Si/P molar ratio decreases, the amorphous phase content increases. Besides, the structural analyses have revealed the presence of aluminum phosphate and Si-O-Al-O-P polymeric structure, whatever the Si/P molar ratio is (between 2.25 and 3.5. The obtained results have confirmed that the presence of the associated minerals such as hematite and quartz in the clay does not prevent the geopolymerization reaction, but the presence of illite mineral seems to have a modest contribution in the geopolymerization.

  11. Boron enrichment in martian clay.

    Directory of Open Access Journals (Sweden)

    James D Stephenson

    Full Text Available We have detected a concentration of boron in martian clay far in excess of that in any previously reported extra-terrestrial object. This enrichment indicates that the chemistry necessary for the formation of ribose, a key component of RNA, could have existed on Mars since the formation of early clay deposits, contemporary to the emergence of life on Earth. Given the greater similarity of Earth and Mars early in their geological history, and the extensive disruption of Earth's earliest mineralogy by plate tectonics, we suggest that the conditions for prebiotic ribose synthesis may be better understood by further Mars exploration.

  12. Strength Properties of Aalborg Clay

    DEFF Research Database (Denmark)

    Iversen, Kirsten Malte; Nielsen, Benjaminn Nordahl; Augustesen, Anders Hust

    resulted in many damaged buildings in Aalborg. To provide sufficient bearing capacity it is therefore necessary either to remove the fill or to construct the building on piles. Both methods imply that the strength of Aalborg Clay is important for the construction. This paper evaluates the strength...... of Aalborg Clay by use of triaxial tests from four different locations. Both the drained strength (c and ϕ) and the undrained strength (cu) are assessed through two different methods: one where the strength is assumed to vary with the effective stress and another where the strength is found to be constant....

  13. Role of clay constituents in stone decay processes

    Directory of Open Access Journals (Sweden)

    Veniale, F.

    2001-12-01

    Full Text Available Stone alterability/durability is depending upon a number of intrinsic and extrinsic factors among which "clay minerals" constituents, either diffused throughout the stone framework or as coating-filling of void spaces, can play an important role. Swelling-shrinking and aggregation-disaggregation phenomena occurring by interaction of argillaceous particles with water and other fluids can cause destructuration of the stone resulting in a variety of pathologies. Also salt crystallization which is depending on fluid transfer, moisture evaporation and ion concentration in the circulating solutions, can be influenced by clay mineral reactivity. Furthermore, saline solutions can drastically change the clay minerals behaviour, resulting in enhanced "osmotic" swelling and variations in clay aggregation geometry; these phenomena resulting in significant stone damage. Case histories concerning several lithotypes used for monumental buildings and artistic manufacts are reported for showing the role of different clay mineral types in determining trend and intensity of decay processes.

    Varios factores, tanto intrínsecos como extrínsecos, pueden condicionar la alterabilidad/durabilidad de materiales pétreos. Entre ellos, la presencia de minerales arcillosos, bien como constituyentes difusos o recubriendo-rellenando huecos, puede jugar un papel importante. El resultado de la interacción de las partículas arcillosas y el agua (u otros fluidos da lugar a patologías que son consecuencia de una serie de daños internos producidos por las continuas variaciones plásticas, asociadas a parámetros físicos y cristaloquímicos de este tipo de minerales. Entre los que podemos citar la desestructuración de la piedra (bien por agregación-desagregación de las partículas arcillosas o por procesos de hinchamiento-contracción que está asociado, por ejemplo, con la cristalización de sales, producida por la transferencia de fluidos a su través, o a

  14. Clay membrane made of natural high plasticity clay

    DEFF Research Database (Denmark)

    Foged, Niels; Baumann, Jens

    1998-01-01

    Leachate containment in Denmark has through years been regulated by the DIF Recommendation for Sanitary Landfill Liners (DS/R 466). It states natural clay deposits may be used for membrane material provided the membrane and drainage system may contain at least 95% of all leachate created throughout...

  15. Sand and clay mineralogy of sal forest soils of the Doon Siwalik Himalayas

    Indian Academy of Sciences (India)

    Mukesh; R K Manhas; A K Tripathi; A K Raina; M K Gupta; S K Kamboj

    2011-02-01

    The peteromineralogical characterization of the soil was carried out for the 12 soil profiles exposed in the Shorea robusta dominated forests of the Siwalik forest division, Dehradun. The quartz was observed as the dominating light mineral fraction (64–80%) in all the profiles studied. Biotite, hornblende, zircon, tourmaline, rutile and opaques comprising of iron minerals constituted the heavy mineral fraction (20%). The mineralogy of both the sand and clay fractions revealed a mixed mineralogy. The clay minerals in the order of their dominance were vermiculite, illite, kaolinite and mixed layer minerals. The presence of vermiculite and illite in appreciable quantities indicates that these were synthesized from the K-rich soil solution, as orthoclase and micas were present in significant quantities in the sand minerals. The mineral suites identified in the study shows that the geological, climatological and topographical factors of the region collectively played a dominant role in their formation and transformation. After critical appraisal of the results, it may be deduced that the mineralogical composition, physicochemical properties and total elemental analysis of the soils do not show any deficiency of the bases and other plant nutrients in general. The inherent fertility of the soil is good as indicated by the sand and clay mineralogy of the soil and the biotite and feldspar together with the mica is an important source of nutrients for the vegetation in the soils of the Doon valley.

  16. Mineralogy of subducted clay and clay restite in the lower mantle

    Science.gov (United States)

    Armstrong, L.; Skora, S. E.; Walter, M. J.

    2012-12-01

    Seismic tomography indicates that subducting oceanic lithosphere often penetrates the transition zone and eventually the lower mantle [e.g. 1, 2]. While mineralogical changes in the mafic and ultramafic portions of slabs have been well documented experimentally, the phase relations of overlying sediments at pressures above 25 GPa remain poorly studied. This is in part because sediments are expected to partially melt at sub-arc depth (P~2.5-4.5 GPa), and contribute to the genesis of arc magmas. Sediment restites left behind after the extraction of low pressure melts undergo major chemical changes, according to the melting reaction: Coe+Phen+Cpx+H2O = Grt+Ky+Melt [3]. However, sediments may not always melt depending on the thermal regime and volatile availability and composition [3]. Hence, chemically unmodified sediments as well as restites may be entrained to greater depths and contribute to compositional heterogeneity in the deep mantle. Indeed, mineral inclusions with compositions indicative of subducted sedimentary protoliths (CAS-phase; K-hollandite; stishovite) have been reported in 'ultradeep' diamonds and suggest that deep subduction and survival of sediments occurs to at least transition zone depths [4]. With this in mind, we have performed laser heated diamond anvil cell experiments at pressures of 8-80 GPa on two anhydrous glass starting materials: a marine clay and the restite that is left after 50% melt extraction of this clay at 3 GPa and 800 °C [3]. We chose to work with an anhydrous version of the marine clay given that the investigated pressure range exceeds that of phengite stability [5], and phengite is the only hydrous phase in subducted sediments at UHP conditions. The clay was heated along a P-T path representative of a cold subduction geotherm, whereas the clay restite was heated along a hotter subduction geotherm consistent with low pressure melting. Phases were identified by synchrotron X-ray micro-diffraction at beamline I15 of the Diamond

  17. Mitigating Fish-Killing Prymnesium parvum Algal Blooms in Aquaculture Ponds with Clay: The Importance of pH and Clay Type

    Directory of Open Access Journals (Sweden)

    Andreas Seger

    2015-04-01

    Full Text Available Clay minerals have previously been used to mitigate algal blooms because of their ability to flocculate algal cells or remove nutrients, but also offer considerable potential to remove ichthyotoxins. When a barramundi farm in tropical Australia suffered substantial fish mortalities due to a bloom of the ichthyotoxic haptophyte Prymnesium parvum, the farm manager decided to manipulate pond water N:P ratios through removal of phosphorus by the addition of lanthanum-modified bentonite clay (Phoslock™ to successfully mitigate ichthyotoxic effects. We conducted Prymnesium culture experiments under a range of N:P ratios, screening 14 different clays (two zeolites, four kaolins, six bentonites and two types of Korean loess at pH 7 and 9 for cell flocculation and removal of ichthyotoxicity assessed with the RTgill-W1 cell line assay. Application of Phoslock™ to cultures grown at different N:P effectively removed 60%–100% of water-soluble toxicity of live Prymnesium (dependent on nutritional status. While most clays efficiently flocculated Prymnesium cells (≥80% removal, cell removal proved a poor predictor of ichthyotoxin adsorption. Extensive clay screening revealed that at elevated pH, as commonly associated with dense algal blooms, most clays either exacerbated ichthyotoxicity or exhibited significantly reduced toxin adsorption. Interpretation of changes in clay zeta potential at pH 7 and 9 provided valuable insight into clay/ichthyotoxin interactions, yet further research is required to completely understand the adsorption mechanisms. Bentonite-type clays proved best suited for ichthyotoxin removal purposes (100% removal at ecologically relevant pH 9 and offer great potential for on-farm emergency response.

  18. Mineral oils

    Science.gov (United States)

    Furby, N. W.

    1973-01-01

    The characteristics of lubricants made from mineral oils are discussed. Types and compositions of base stocks are reviewed and the product demands and compositions of typical products are outlined. Processes for commercial production of mineral oils are examined. Tables of data are included to show examples of product types and requirements. A chemical analysis of three types of mineral oils is reported.

  19. 30 CFR 46.5 - New miner training.

    Science.gov (United States)

    2010-07-01

    ... RETRAINING OF MINERS ENGAGED IN SHELL DREDGING OR EMPLOYED AT SAND, GRAVEL, SURFACE STONE, SURFACE CLAY, COLLOIDAL PHOSPHATE, OR SURFACE LIMESTONE MINES. § 46.5 New miner training. (a) Except as provided in... the recognition and avoidance of electrical hazards and other hazards present at the mine, such...

  20. Biodegradable Pectin/clay Aerogels

    Science.gov (United States)

    Biodegradable, foamlike materials based on renewable pectin and sodium montmorillonite clay were fabricated through a simple, environmentally friendly freeze-drying process. Addition of multivalent cations (Ca2+ and Al3+) resulted in apparent crosslinking of the polymer, and enhancement of aerogel p...

  1. Picasso Masks: Cubism in Clay

    Science.gov (United States)

    Daddino, Michelle

    2010-01-01

    This article describes an art project developed by the author which provides a way to further the children's understanding of Picasso's Cubism style in 3-D. Through this project, upper-elementary students learn a bit about the life and art of Picasso as they gain a firm understanding of the style of art known as Cubism, and apply clay techniques…

  2. ADSORPTION OF SURFACTANT ON CLAYS

    Science.gov (United States)

    Surfactants used to enhance remediation of soils by soil washing are often lost in the process. Neither the amount nor the cause of this loss is known. It is assumed that clays present in the soil are responsible for the loss of the surfactant. In this papere, adsorption prope...

  3. Clay-Nucleic Acid Complexes: Characteristics and Implications for the Preservation of Genetic Material in Primeval Habitats

    Science.gov (United States)

    Franchi, Marco; Bramanti, Emilia; Morassi Bonzi, Laura; Luigi Orioli, Pier; Vettori, Cristina; Gallori, Enzo

    1999-05-01

    The equilibrium adsorption of three nucleic acids: chromosomal DNA, supercoiled plasmid DNA, and 25S rRNA, on the clay minerals, montmorillonite (M) and kaolinite (K), were studied. Adsorption of the nucleic acid on the clays was rapid and maximal after 90 min of contact time. Chromosomal DNA was adsorbed to a greater extent than plasmid DNA and RNA, and the adsorption was also greater on M than on K. Adsorption isotherms were of the L type, and a plateau was reached with all the complexes, with the exception of chromosomal DNA adsorbed on M. To determine where nucleic acids are adsorbed on clay minerals and the nature of the interaction, complexes were studied by X-ray diffraction (X-RD), electron microscopy, and Fourier transform infrared (FT-IR) spectroscopy. X-RD showed that nucleic acids did not penetrate the clay, indicating that the adsorption occurred primarily on the external surfaces of clay particles, as also suggested by electron microscopy observations. FT-IR spectra of clay-tightly bound nucleic acid complexes showed absorption bands that indicate a variation of the nucleic acids status as a consequence of their adsorption on clay. Data obtained suggested that the formation of clay-nucleic acid complex could have an important role in the preservation of genetic material in primeval habitats.

  4. Effect of mechanical and chemical clay removals by hydrocyclone and dispersants on coal flotation

    Energy Technology Data Exchange (ETDEWEB)

    Oats, W.J.; Ozdemir, O.; Nguyen, A.V. [University of Queensland, Brisbane, Qld. (Australia). School of Chemical Engineering

    2010-04-15

    Fine minerals, mostly clays, are known to have a detrimental effect on coal flotation. This paper focuses on the effect of mechanical and chemical removals of fine minerals by hydrocyclone and dispersants on coal flotation. The experimental results showed that the flotation recovery slightly increased from medium acidic to medium alkaline ranges. The flotation experiments carried out with dispersants at different dosages showed that the dispersants did not enhance the flotation recovery significantly. However, the removal of the fine fraction from the feed using a hydrocyclone significantly increased the flotation recovery. The bubble-particle attachment tests also indicated that the attachment time between an air bubble and the coal particles increased in the presence of clay particles. These attachment time results clearly showed that the clay particles adversely affected the flotation of coal particles by covering the coal surfaces which reduced the efficiency of bubble-coal attachment. An analysis based on the colloid stability theory showed that the clay coating was governed by the van der Waals attraction and that the double-layer interaction played a secondary role. It was also concluded that the best way to increase the flotation recovery in the presence of clays was to remove these fine minerals by mechanical means such as hydrocylones.

  5. Evaluation of used fuel disposition in clay-bearing rock

    Energy Technology Data Exchange (ETDEWEB)

    Jove-Colon, Carlos F. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hammond, Glenn Edward [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Kuhlman, Kristopher L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Zheng, Liange [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Kim, Kunhwi [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Xu, Hao. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Rutqvist, Jonny [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Caporuscio, Florie Andre [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Norskog, Katherine E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Maner, James [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Palaich, Sarah [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Cheshire, Michael [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Zavarin, Mavrik [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Wolery, Thomas J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Atkins-Duffin, Cindy [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Jerden, James L. [Argonne National Lab. (ANL), Argonne, IL (United States); Copple, Jacqueline M. [Argonne National Lab. (ANL), Argonne, IL (United States); Cruse, Terry [Argonne National Lab. (ANL), Argonne, IL (United States); Ebert, William L. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-09-01

    The R&D program from the DOE Used Fuel Disposition Campaign (UFDC) has documented key advances in coupled Thermal-Hydrological-Mechanical-Chemical (THMC) modeling of clay to simulate its complex dynamic behavior in response to thermal and hydrochemical feedbacks. These efforts have been harnessed to assess the isolation performance of heat-generating nuclear waste in a deep geological repository in clay/shale/argillaceous rock formations. This report describes the ongoing disposal R&D efforts on the advancement and refinement of coupled THMC process models, hydrothermal experiments on barrier clay interactions, used fuel and canister material degradation, thermodynamic database development, and reactive transport modeling of the near-field under non-isothermal conditions. These play an important role to the evaluation of sacrificial zones as part of the EBS exposure to thermally-driven chemical and transport processes. Thermal inducement of chemical interactions at EBS domains enhances mineral dissolution/precipitation but also generates mineralogical changes that result in mineral H2O uptake/removal (hydration/dehydration reactions). These processes can result in volume changes that can affect the interface / bulk phase porosities and the mechanical (stress) state of the bentonite barrier. Characterization studies on bentonite barrier samples from the FEBEX-DP international activity have provided important insight on clay barrier microstructures (e.g., microcracks) and interactions at EBS interfaces. Enhancements to the used fuel degradation model outlines the need to include the effects of canister corrosion due the strong influence of H2 generation on the source term.

  6. Sorption and desorption of carbamazepine from water by smectite clays.

    Science.gov (United States)

    Zhang, Weihao; Ding, Yunjie; Boyd, Stephen A; Teppen, Brian J; Li, Hui

    2010-11-01

    Carbamazepine is a prescription anticonvulsant and mood stabilizing pharmaceutical administered to humans. Carbamazepine is persistent in the environment and frequently detected in water systems. In this study, sorption and desorption of carbamazepine from water was measured for smectite clays with the surface negative charges compensated with K+, Ca2+, NH4+, tetramethylammonium (TMA), trimethylphenylammonium (TMPA) and hexadecyltrimethylammonium (HDTMA) cations. The magnitude of sorption followed the order: TMPA-smectite≥HDTMA-smectite>NH4-smectite>K-smectite>Ca-smectite⩾TMA-smectite. The greatest sorption of carbamazepine by TMPA-smectite is attributed to the interaction of conjugate aromatic moiety in carbamazepine with the phenyl ring in TMPA through π-π interaction. Partitioning process is the primary mechanism for carbamazepine uptake by HDTMA-smectite. For NH4-smectite the urea moiety in carbamazepine interacts with exchanged cation NH4+ by H-bonding hence demonstrating relatively higher adsorption. Sorption by K-, Ca- and TMA-smectites from water occurs on aluminosilicate mineral surfaces. These results implicate that carbamazepine sorption by soils occurs primarily in soil organic matter, and soil mineral fractions play a secondary role. Desorption of carbamazepine from the sorbents manifested an apparent hysteresis. Increasing irreversibility of desorption vs. sorption was observed for K-, Ca-, TMA-, TMPA- and HDTMA-clays as aqueous carbamazepine concentrations increased. Desorption hysteresis of carbamazepine from K-, Ca-, NH4-smectites was greater than that from TMPA- and HDTMA-clays, suggesting that the sequestrated carbamazepine molecules in smectite interlayers are more resistant to desorption compared to those sorbed by organic phases in smectite clays.

  7. Mineralogical characterization of clays used in the structural ceramic industry in west of S. Paulo State, Brazil Caracterização mineralógica de argilas usadas na indústria de cerâmica estrutural no oeste do estado de S. Paulo, Brasil

    Directory of Open Access Journals (Sweden)

    S. R. Teixeira

    2001-12-01

    Full Text Available Plasticity and the grain-size distribution of the raw material used to make structural bricks and roof tiles are very important to the production process. These two parameters and the mineral composition will define the quality and properties of the final product: color, mechanical resistance, water absorption, cracks, swell and shrink during drying and firing the ceramic pieces etc. In the Brazilian ceramic industry it is very common to mix together two or more different kinds of raw material to achieve the ceramic mass with the desired grain-size distribution. The objective of this work was to characterize the raw material collected at the floodplains of the Paraná and Paranapanema Rivers and the ceramic mass used by the ceramic industry in western São Paulo State, Brazil. Particle size distribution, organic matter and X-ray diffraction were used to study this material. The textural analysis indicates that the raw materials have the clay fraction ranging from 38.2% to 66.3%, the silt from 22.2% to 49.7% and the sand from 3.1% to 34.1%. The results indicate that all mixed raw materials have more clay in its composition than would be necessary. The organic matter ranges from 5 to 7%. All samples have kaolinite and many of them have smectites, HIV and mica. Gibbsite, iron and titanium oxides, and quartz are also identified. One of the samples (yellow is rich in goethite.A plasticidade e a granulometria da massa cerâmica são dois parâmetros importantes para o processo de produção de tijolos e telhas. Estes dois parâmetros e a composição mineralógica definirão a qualidade e propriedades (cor, resistência mecânica, absorção de água, trincas, mudanças nas dimensões durante a secagem e queima, etc. do produto final. Na indústria cerâmica brasileira é comum misturar dois ou mais tipos de "barro" para se obter a massa cerâmica com a granulometria e plasticidade desejada. O objetivo deste trabalho foi caracterizar a matéria prima

  8. Evidence for Smectite Clays from MSL SAM Analyses of Mudstone at Yellowknife Bay, Gale Crater, Mars

    Science.gov (United States)

    McAdam, Amy; Franz, Heather; Mahaffy, Paul R.; Eigenbrode, Jennifer L.; Stern, Jennifer C.; Brunner, Anna; Archer, Paul Douglas; Ming, Douglas W.; Morris, Richard V.; Atreya, Sushil K.

    2013-01-01

    Drilled samples of mudstone from the Sheepbed unit at Yellowknife Bay were analyzed by MSL instruments including the Sample Analysis at Mars (SAM) and Chemistry and Mineralogy (CheMin) instruments in MSL's Analytical Laboratory. CheMin analyses revealed the first in situ X-ray diffraction based evidence of clay minerals on Mars, which are likely trioctahedral smectites (e.g., saponite) and comprise approx 20% of the mudstone sample (e.g., Bristow et al., this meeting). SAM analyses, which heated the mudstone samples to 1000 C and monitored volatiles evolved to perform in situ evolved gas analysis mass spectrometry (EGA-MS), resulted in a H2O trace exhibiting a wide evolution at temperatures clay mineral. Comparison to EGA-MS data collected under SAM-like conditions on a variety of clay mineral reference materials indicate that a trioctahedral smectite, such as saponite, is most consistent with the high temperature H2O evolution observed. There may also be SAM EGA-MS evidence for a small high temperature H2O evolution from scoop samples from the Yellowknife Bay Rocknest sand shadow bedform. As in the mudstone samples, this evolution may indicate the detection of smectite clays, and the idea that minor clays may be present in Rocknest materials that could be expected to be at least partially derived from local sources is reasonable. But, because smectite clays were not definitively observed in CheMin analyses of Rocknest materials, they must be present at much lower abundances than the approx 20% observed in the mudstone samples. This potential detection underscores the complementary nature of the MSL CheMin and SAM instruments for investigations of martian sample mineralogy. Information on the nature of Yellowknife Bay clay minerals may also be available from the detection of H2 evolved during SAM EGA-MS at high temperature. A likely source of at least some of this H2 is H2O evolved from the smectite clays at high temperature, and it is possible these evolutions can

  9. Effect of electrolyte on the microstructure and yielding of aqueous dispersions of colloidal clay

    OpenAIRE

    Ali, Samim; Bandyopadhyay, Ranjini

    2015-01-01

    Na-montmorillonite is a natural clay mineral and is available in abundance in nature. The aqueous dispersions of charged and anisotropic platelets of this mineral exhibit non-ergodic kinetically arrested states ranging from soft glassy phases dominated by interparticle repulsions to colloidal gels stabilized by salt induced attractive interactions. When the salt concentration in the dispersing medium is varied systematically, visco