Science.gov

Sample records for clay

  1. Ball clay

    USGS Publications Warehouse

    Virta, Robert L.

    2010-01-01

    The article reports on the global market performance of ball clay in 2009 and presents an outlook for its 2010 performance. Several companies mined ball call in the country including Old Hickey Clay Co., Kentucky-Tennessee Clay Co., and H.C. Spinks Clay Co. Information on the decline in ball clay imports and exports is also presented.

  2. Clays, specialty

    USGS Publications Warehouse

    Virta, R.L.

    1998-01-01

    Part of a special section on the state of industrial minerals in 1997. The state of the specialty clay industry worldwide for 1997 is discussed. The specialty clays mined in the U.S. are ball clay, fuller's earth, bentonite, fire clay, and kaolin. Sales of specialty clays in the U.S. were around 17 Mt in 1997. Approximately 53 kt of specialty clays were imported.

  3. Ball clay

    USGS Publications Warehouse

    Virta, R.L.

    2006-01-01

    In 2005, four companies including H.C. Spinks Clay, Kentucky-Tennessee Clay, Old Hickory Clay and Unimin mined ball clay in four states. Based on a preliminary survey of the ball clay industry, production reached 1.32 Mt valued at $53.3 million. Tennessee was the leading ball clay producer state with 61% of domestic production, followed by Texas, Mississippi and Kentucky.

  4. Clay Play

    ERIC Educational Resources Information Center

    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…

  5. Ball clay

    USGS Publications Warehouse

    Virta, R.L.

    2001-01-01

    Part of the 2000 annual review of the industrial minerals sector. A general overview of the ball clay industry is provided. In 2000, sales of ball clay reached record levels, with sanitary ware and tile applications accounting for the largest sales. Ball clay production, consumption, prices, foreign trade, and industry news are summarized. The outlook for the ball clay industry is also outlined.

  6. Ball clay

    USGS Publications Warehouse

    Virta, R.L.

    2007-01-01

    The article offers information on ball clay. Among the companies that mine ball clay in the U.S. are H.C. Spinks Clay, Kentucky-Tennessee Clay and Old Hickory Clay. In 2006, an estimated 1.2 million tons of the mineral was sold or used domestically and exported. Forty-percent of the total sales is accounted for ceramic floor and wall tile followed by sanitaryware and miscellaneous ceramics. Its average value was $ 45 per ton in 2006.

  7. Ball clay

    USGS Publications Warehouse

    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.

  8. Ball clay

    USGS Publications Warehouse

    Virta, R.L.

    2013-01-01

    Four companies — H.C. Spinks Clay Co., Inc., Imerys, Old Hickory Clay Co. and Unimin Corp. — mined ball clay in five U.S. states in 2012. Production, on the basis of preliminary data, was 900 kt (992,000 st), with an estimated value of $42.3 million. This was a slight increase in tonnage from 886 kt (977,000 st), with a value of $40.9 million in 2011. Tennessee was the leading ball clay producing state, with 63 percent of domestic production, followed by Texas, Mississippi, Kentucky and Indiana. Reported ball clay production from Indiana probably was fire clay rather than ball clay. About 69 percent of total ball clay production was airfloat, 20 percent was crude and 11 percent was water-slurried.

  9. Fire clay

    USGS Publications Warehouse

    Virta, R.L.

    2011-01-01

    The article discusses the latest developments in the fire clay industry, particularly in the U.S., as of June 2011. It claims that the leading fire clay producer in the U.S. is the state of Missouri. The other major producers include California, Texas and Washington. It reports that the use of heavy clay products made of fire clay like brick, cement and lightweight aggregate has increased slightly in 2010.

  10. Clays, common

    USGS Publications Warehouse

    Virta, R.L.

    1998-01-01

    Part of a special section on the state of industrial minerals in 1997. The state of the common clay industry worldwide for 1997 is discussed. Sales of common clay in the U.S. increased from 26.2 Mt in 1996 to an estimated 26.5 Mt in 1997. The amount of common clay and shale used to produce structural clay products in 1997 was estimated at 13.8 Mt.

  11. Clay Houses

    ERIC Educational Resources Information Center

    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.

  12. Fire clay

    USGS Publications Warehouse

    Virta, R.L.

    2013-01-01

    Four companies mined fire clay in three states in 2012. Production, based on a preliminary survey of the fire clay industry, was estimated to be 230 kt (254,000 st) valued at $6.98 million, an increase from 215 kt (237,000 st) valued at $6.15 million in 2011. Missouri was the leading producing state, followed by Colorado and Texas, in decreasing order by quantity. The number of companies mining fire clay declined in 2012 because several common clay producers that occasionally mine fire clay indicated that they did not do so in 2012.

  13. Fire clay

    USGS Publications Warehouse

    Virta, R.L.

    2006-01-01

    In 2005, six companies mined fire clay in Missouri, Ohio and South Carolina. Production was estimate to be 300 kt with a value of $8.3 million. Missouri was the leading producer state followed by Ohio and South Carolina. For the third consecutive year, sales and use of fire clays have been relatively unchanged. For the next few years, sales of fire clay is forecasted to remain around 300 kt/a.

  14. Ball clay

    USGS Publications Warehouse

    Virta, R.L.

    2000-01-01

    Part of the 1999 Industrial Minerals Review. The state of the ball clay industry in 1999 is presented. Record highs in the sales and use of ball clay were attained in 1999 due to the continued strength of the U.S. economy. U.S. production was estimated at 1.25 million st for the year, with more than half of that amount mined in Tennessee. Details of the consumption, price, imports, and exports of ball clay in 1999 and the outlook for ball clay over the next few years are provided.

  15. Fire clay

    USGS Publications Warehouse

    Virta, R.L.

    2012-01-01

    Five companies mined fire clay in four states in 2011. Production, based on a preliminary survey of the fire clay industry, was estimated to be 240 kt (265,000 st), valued at $7.68 million, an increase from 216 kt (238,000 st), valued at $6.12 million in 2010. Missouri was the leading producing state, followed by Texas, Washington and Ohio, in decreasing order by quantity.

  16. Clay Minerals

    SciTech Connect

    Mueller, Karl T.; Sanders, Rebecca L.; Washton, Nancy M.

    2014-03-14

    Clay minerals are important components of the environment and are involved or implicated in processes such as the uptake of pollutants and the release of nutrients and as potential platforms for a number of chemical reactions. Owing to their small particle sizes (typically, on the order of microns or smaller) and mixing with a variety of other minerals and soil components, advanced characterization methods are needed to study their structures, dynamics, and reactivities. In this article, we describe the use of solid-state NMR methods to characterize the structures and chemistries of clay minerals. Early one-pulse magic-angle spinning (MAS) NMR studies of 27Al and 29Si have now been enhanced and extended with new studies utilizing advanced methodologies (such as Multiple Quantum MAS) as well as studies of less-sensitive nuclei. In additional work, the issue of reactivity of clay minerals has been addressed, including studies of reactive surface area in the environment. Utilizations of NMR-sensitive nuclides within the clay minerals themselves, and in molecules that react with specific sites on the clay mineral surfaces, have aided in understanding the reactivity of these complex aluminosilicate systems.

  17. Ball clay

    USGS Publications Warehouse

    Virta, R.L.

    2012-01-01

    Four companies — H.C. Spinks Clay Co., Inc., Imerys Group, Old Hickory Clay Co., and Unimin Corp. — mined ball clay in four states in 2011. Production, on the basis of preliminary data, was 940 kt (1.04 million st) with an estimated value of $44.2 million. This is a 3-percent increase in tonnage from 912 kt (1.01 million st) with a value of $41.3 million that was produced in 2010. Tennessee was the leading producing state with 63 percent of domestic production, followed by Texas, Mississippi and Kentucky. About 69 percent of production was airfloat, 20 percent was crude and 11 percent was water-slurried.

  18. Clay for Little Fingers.

    ERIC Educational Resources Information Center

    Koster, Joan Bouza

    1999-01-01

    Discusses the renewed interest in clay as a modeling compound in early childhood programs; describes the nature of clay and presents a working vocabulary. Suggests methods of working with clay, including introducing clay to children, discovering its uses, clean up, firing clay, and finishing baked clay. Includes activity suggestions and…

  19. Fire clay

    USGS Publications Warehouse

    Virta, R.L.

    2004-01-01

    Seven companies mined fire clay in four states during 2003. From 1984 to 1992, production declined to 383 kt (422,000 st) from a high of 1.04 Mt (1.14 million st) as markets for clay-based refractories declined. Since 1992, production levels have been erratic, ranging from 383 kt (422,000 st) in 1992 and 2001 to 583 kt (642,000 st) in 1995. Production in 2003, based on preliminary data, was estimated to be around 450 kt (496,000 st) with a value of about $10.5 million. This was about the same as in 2002. Missouri remained the leading producer state, followed by South Carolina, Ohio and California.

  20. Killer clays! Natural antibacterial clay minerals

    USGS Publications Warehouse

    Williams, L.B.; Holland, M.; Eberl, D.D.; Brunet, T.; De Courrsou, L. B.

    2004-01-01

    The clay chemical properties that may be important in medicine were investigated. It was found that natural clay minerals can have striking and very specific effects on microbial populations. The effects can range from potentially enhanced microbial growth to complete sterilization. This paper presents evidence that natural clay minerals can be effective antimicrobial agents.

  1. CLAY AND CLAY-SUPPORTED REAGENTS IN ORGANIC SYNTHESES

    EPA Science Inventory

    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...

  2. Imprinted Clay Coil Vessels

    ERIC Educational Resources Information Center

    Lohr, Tresa Rae

    2006-01-01

    The author teaches clay vessel construction in the fifth grade, and it is amazing what can be accomplished in one forty-five minute period when the expectations are clarified in the initial lesson. The author introduces clay coil vessels with a discussion of the sources of clay and how clay relates to fifth-grade science curriculum concepts such…

  3. Common clay and shale

    USGS Publications Warehouse

    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.

  4. Communicating with Clay.

    ERIC Educational Resources Information Center

    Skophammer, Karen

    2000-01-01

    Presents a unit on clay that is centered around sign language in which students explore the slab method of working with clay. States that each student picks a letter of the sign language alphabet and fashions a clay hand to depict the letter. (CMK)

  5. Clays in prebiological chemistry

    NASA Technical Reports Server (NTRS)

    Rao, M.; Oro, J.; Odom, D. G.

    1980-01-01

    The ways in which clays have been utilized in studies of prebiological chemistry are reviewed, and an assessment is given of the possible role of clays in prebiological systems. The adsorption of organic molecules on clays has been demonstrated, as has the synthesis of bioorganic monomers in the presence of clays. For instance, amino acids, purines and pyrimidines have been obtained from carbon monoxide and nitric acid in the presence of clays at relatively high temperatures (250-325 C). The oligomerization of biochemical monomers, mediated by clays, has also been shown to result in the formation of polymer molecules basic to life. Clays have also been found to affect the condensation of mononucleotides to oligonucleotides.

  6. Modified clay sorbents

    DOEpatents

    Fogler, H. Scott; Srinivasan, Keeran R.

    1990-01-01

    A novel modified clay sorbent and method of treating industrial effluents to remove trace pollutants, such as dioxins, biphenyls, and polyaromatics such as benzo(a)pyrene and pentachlorophenol. The novel clay sorbent has a composite structure in which the interlayer space of an expandable clay, such as smectite, is filled with polyvalent or multivalent inorganic cations which forces weaker surfactant cations to locate on the surface of the clay in such an orientation that the resulting composite is hydrophilic in nature. A specific example is cetylpyridinium-hydroxy aluminum-montmorillonite. In certain embodiments, a non-expanding clay, such as kaolinite, is used and surfactant cations are necessarily located on an external surface of the clay. A specific example is cetylpyridinium-kaolinite.

  7. Permeability of Clay Concretes

    NASA Astrophysics Data System (ADS)

    Solomon, F.; Ekolu, S. O.

    2015-11-01

    This paper presents an investigation on the effect of clay addition on water permeability and air permeability of concretes. Clay concrete mixes consisted of 0 to 40% clay content incorporated as cement replacement. Flow methods using triaxial cells and air permeameters were used for measuring the injected water and air flows under pressure. It was found that the higher the clay content in the mixture, the greater the permeability. At higher water-cement ratios (w/c), the paste matrix is less dense and easily allows water to ingress into concrete. But at high clay contents of 30 to 40% clay, the variation in permeability was significantly diminished among different concrete mixtures. It was confirmed that air permeability results were higher than the corresponding water permeability values when all permeability coefficients were converted to intrinsic permeability values.

  8. Common clay and shale

    USGS Publications Warehouse

    Virta, R.L.

    2000-01-01

    Part of the 1999 Industrial Minerals Review. The clay and shale market in 1999 is reviewed. In the U.S., sales or use of clay and shale increased from 26.4 million st in 1998 to 27.3 million st in 1999, with an estimated 1999 value of production of $143 million. These materials were used to produce structural clay products, lightweight aggregates, cement, and ceramics and refractories. Production statistics for clays and shales and for their uses in 1999 are presented.

  9. Clay Mineral: Radiological Characterization

    NASA Astrophysics Data System (ADS)

    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.

  10. The Science of Clay

    ERIC Educational Resources Information Center

    Warwick, Sharon

    2005-01-01

    Students' natural curiosity provides a rich opportunity for teachers to make meaningful scientific connections between art and ceramics that will enhance the understanding of both natural forces and scientific aspects at work in the creation of clay artworks. This article discusses the scientific areas of study related to clay, which include…

  11. Common clay and shale

    USGS Publications Warehouse

    Virta, R.L.

    2003-01-01

    Part of the 2002 industrial minerals review. The production, consumption, and price of shale and common clay in the U.S. during 2002 are discussed. The impact of EPA regulations on brick and structural clay product manufacturers is also outlined.

  12. Finicky clay divers

    NASA Astrophysics Data System (ADS)

    Cordry, Sean M.

    1998-02-01

    Clay spheres dropped into a dilute vinegar/baking-soda solution accumulate CO2 bubbles on their surfaces. Spheres below a certain size will then float, otherwise they remain sunken. Students must determine the maximum size that will float by considering the net density of the clay/bubble system.

  13. Clay Portrait Boxes

    ERIC Educational Resources Information Center

    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…

  14. Columns in Clay

    ERIC Educational Resources Information Center

    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…

  15. Clays as prebiotic photocatalysts

    NASA Technical Reports Server (NTRS)

    Coyne, L. M.; Lawless, J.; Lahav, N.; Sutton, S.; Sweeney, M.

    1981-01-01

    Clay minerals catalyze peptide bond formation in fluctuating environments. A number of plausible mechanisms have been proposed and tested. The possibility that clays may actually be energizing the reaction by means of electronic excitation, creating mobile or trapped holes and electrons in the lattice, is explored. It has been discovered that clays emit light upon dehydration. The correlation between dehydration-induced, or thermoluminescent, processes and the yield of glycine oligomers after treatments known to affect the luminescent yields is being tested, in an effort to understand the catalytic mechanism

  16. Common clay and shale

    USGS Publications Warehouse

    Virta, R.L.

    2004-01-01

    Part of the 2003 industrial minerals review. The legislation, production, and consumption of common clay and shale are discussed. The average prices of the material and outlook for the market are provided.

  17. Common clay and shale

    USGS Publications Warehouse

    Virta, R.L.

    2006-01-01

    At present, 150 companies produce common clay and shale in 41 US states. According to the United States Geological Survey (USGS), domestic production in 2005 reached 24.8 Mt valued at $176 million. In decreasing order by tonnage, the leading producer states include North Carolina, Texas, Alabama, Georgia and Ohio. For the whole year, residential and commercial building construction remained the major market for common clay and shale products such as brick, drain tile, lightweight aggregate, quarry tile and structural tile.

  18. Clay Mineral: Radiological Characterization

    SciTech Connect

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

    2008-08-07

    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 {sup 40}K in these clay minerals.The objective of this work is to determine the concentrations of {sup 238}U, {sup 232}Th, {sup 226}Ra, {sup 228}Ra, {sup 210}Pb and {sup 40}K 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 {sup 238}U and {sup 232}Th activity concentration was made by alpha spectrometry and gamma spectrometry was used for {sup 226}Ra, {sup 228}Ra, {sup 210}Pb and {sup 40}K determination. Some physical-chemical parameters were also determined as organic carbon and pH. The average activity concentration obtained was 906{+-}340 Bq kg{sup -1} for {sup 40}K, 40{+-}9 Bq kg{sup -1} for {sup 226}Ra, 75{+-}9 Bq kg{sup -1} for {sup 228}Ra, 197{+-}38 Bq kg{sup -1} for {sup 210}Pb, 51{+-}26 Bq kg{sup -1} for {sup 238}U and 55{+-}24 Bq kg{sup -1} for {sup 232}Th, considering both kinds of clay.

  19. Designing in Clay

    ERIC Educational Resources Information Center

    Nigrosh, Leon I.

    1977-01-01

    What can be done to transform a lump of wet clay into something more than a lump of glaze-fired clay? It is at this point when forming techniques have been mastered that good design becomes most important. Discusses six criteria involved in the search for good design so that students can discover what good design is and how important it is.…

  20. Rattles of Clay.

    ERIC Educational Resources Information Center

    Banning, Donna

    1983-01-01

    Using the rattles of Native American cultures as inspiration, students used pinching, coiling, and slab and molding techniques to form the bodies of rattles and clay pellets for sound. Surface decoration included glazed and unglazed areas as well as added handles, feathers, and leather. (IS)

  1. Common clay and shale

    USGS Publications Warehouse

    Virta, R.L.

    2001-01-01

    Part of the 2000 annual review of the industrial minerals sector. A general overview of the common clay and shale industry is provided. In 2000, U.S. production increased by 5 percent, while sales or use declined to 23.6 Mt. Despite the slowdown in the economy, no major changes are expected for the market.

  2. Clay Mineral Preferred Orientation

    NASA Astrophysics Data System (ADS)

    Day-Stirrat, R. J.

    2014-12-01

    Anisotropy of the orientation of clay minerals, often referred to as texture, may be unique to sediments' deposition, composition, deformation or diagenetic history. The literature is rich with studies that include preferred orientation generation in fault gouge, low-grade metamorphic rocks, sediments with variable clay content and during the smectite-to-illite transformation. Untangling the interplay between many competing factors in any one geologic situation has proven a significant challenge over many years. Understanding how, where and when clay minerals develop a preferred orientation has significant implications for permeability anisotropy in shallow burial, the way mechanical properties are projected from shallower to deeper settings in basin modeling packages and the way velocity anisotropy is accounted for in seismic data processing. The assessment of the anisotropic properties of fine-grained siliciclastic rocks is gaining significant momentum in rock physics research. Therefore, a fundamental understanding of how clay minerals develop a preferred orientation in space and time is crucial to the understanding of anisotropy of physical properties. The current study brings together a wealth of data that may be used in a predictive sense to account for fabric anisotropy that may impact any number of rock properties.

  3. Clay Animals and Their Habitats

    ERIC Educational Resources Information Center

    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…

  4. Clay at Nili Fossae

    NASA Technical Reports Server (NTRS)

    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

  5. How clays weaken faults.

    NASA Astrophysics Data System (ADS)

    van der Pluijm, Ben A.; Schleicher, Anja M.; Warr, Laurence N.

    2010-05-01

    The weakness of upper crustal faults has been variably attributed to (i) low values of normal stress, (ii) elevated pore-fluid pressure, and (iii) low frictional strength. Direct observations on natural faults rocks provide new evidence for the role of frictional properties on fault strength, as illustrated by our recent work on samples from the San Andreas Fault Observatory at Depth (SAFOD) drillhole at Parkfield, California. Mudrock samples from fault zones at ~3066 m and ~3296 m measured depth show variably spaced and interconnected networks of displacement surfaces that consist of host rock particles that are abundantly coated by polished films with occasional striations. Transmission electron microscopy and X-ray diffraction study of the surfaces reveal the occurrence of neocrystallized thin-film clay coatings containing illite-smectite (I-S) and chlorite-smectite (C-S) phases. X-ray texture goniometry shows that the crystallographic fabric of these faults rocks is characteristically low, in spite of an abundance of clay phases. 40Ar/39Ar dating of the illitic mix-layered coatings demonstrate recent crystallization and reveal the initiation of an "older" fault strand (~8 Ma) at 3066 m measured depth, and a "younger" fault strand (~4 Ma) at 3296 m measured depth. Today, the younger strand is the site of active creep behavior, reflecting continued activation of these clay-weakened zones. We propose that the majority of slow fault creep is controlled by the high density of thin (< 100nm thick) nano-coatings on fracture surfaces, which become sufficiently smectite-rich and interconnected at low angles to allow slip with minimal breakage of stronger matrix clasts. Displacements are accommodated by localized frictional slip along coated particle surfaces and hydrated smectitic phases, in combination with intracrystalline deformation of the clay lattice, associated with extensive mineral dissolution, mass transfer and continued growth of expandable layers. The

  6. Elastic Properties of Clay Minerals

    NASA Astrophysics Data System (ADS)

    Vanorio, T.; Prasad, M.; Nur, A.

    2001-12-01

    We present ultrasonic P- and S-waves velocity measurements on pure clay samples using three different experiment setups. These experiments provided petrophysical and acoustic properties of clay minerals as a function both of mineralogy and compaction. In the first experiment, acoustic measurements were performed on cold-pressed clay aggregates at ambient and at hydrostatic pressure conditions. Porosity and grain density values of the different clay mineralogy aggregates ranged from 4 to 43% and 2.13 to 2.83 g cm-3, respectively. In the second experiment, we measured P-wave velocity and attenuation in a kaolinite-water suspension in which clay concentration was increased up to 60%. In the third experiment, P- and S- wave velocities were measured during uniaxial stress compaction of clay powders. Results from all three experiments revealed low bulk (K) and shear (μ ) moduli for kaolinite, montmorillonite, and smectite; the values range between 6-12 GPa for K and 4-6 GPa for μ , respectively. Using these clay moduli values in effective medium and granular porous media models, velocity is predicted in saturated pure kaolinite samples, kaolinite suspension and shaly sandstones fairly well. Experimental results also showed that water interlayers play an important role in the compaction and strength of clay aggregates. Clay minerals carrying on water interlayers in their structure showed high compaction and strength. This study is relevant for a more reliable assessment of the seismic response in reservoirs and/or basins characterized by clay-bearing formations.

  7. Green Clay Minerals

    NASA Astrophysics Data System (ADS)

    Velde, B.

    2003-12-01

    Color is a problem for scientific study. One aspect is the vocabulary one used to describe color. Mint green, bottle green, and Kelly green are nice names but not of great utility in that people's physical perception of color is not always the same. In some industries, such as colored fabric manufacture, current use is to send a set of standard colors which are matched by the producer. This is similar to the use of the Munsell color charts in geology. None of these processes makes use of physical optical spectral studies. The reason is that they are difficult to obtain and interpret. For a geologist, color is very important but we rarely have the possibility to standardize the method of our color perception. One reason is that color is both a reflective and transmission phenomenon. The thickness of the sample is critical to any transmission characteristics. Hence, a field color determination is different from one made by using a petrographic microscope. Green glauconite in a hand specimen is not the same color in 30 μm thick thin section seen with a microscope using transmitted light.A second problem is that color in a spectral identification is the result of several absorption emissions,with overlapping signal, forming a complicated spectrum. Interpretation depends very greatly on the spectrum of the light source and the conditions of transmission-reflection of the sample. As a result, for this text, we will not attempt to analyze the physical aspect of green in green clays. In the discussion which follows, reference is made concerning color, to thin section microscopic perception.Very briefly, green clay minerals are green, because they contain iron. This is perhaps not a great revelation to mineralogists, but it is the key to understanding the origin and stability of green clay minerals. In fact, iron can color minerals either red or green or in various shades of orange and brown. The color most likely depends upon the relative abundance of the iron ion valence

  8. Mineral resource of the Month: Clay

    USGS Publications Warehouse

    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.

  9. Elastic Properties of Clay Minerals

    NASA Astrophysics Data System (ADS)

    Vanorio, T.; Prasad, M.; Nur, A.

    We present ultrasonic P- and S-waves velocity measurements on pure clay samples us- ing three different experiment setups. These experiments provided petrophysical and acoustic properties of clay minerals as a function both of mineralogy and compaction. In the first experiment, acoustic measurements were performed on cold-pressed clay aggregates at ambient and at hydrostatic pressure conditions. Porosity and grain den- sity values of the different clay mineralogy aggregates ranged from 4 to 43% and 2.13 to 2.83 g cm-3, respectively. In the second experiment, we measured P-wave velocity and attenuation in a kaolinite-water suspension in which clay concentration was in- creased up to 60%. In the third experiment, P- and S- wave velocities were measured during uniaxial stress compaction of clay powders. Results from all three experiments revealed low bulk (K) and shear (µ) moduli for kaolinite, montmorillonite, and smec- tite; the values range between 6-12 GPa for K and 4-6 GPa for µ, respectively. Using these clay moduli values in effective medium and granular porous media (theories) models, velocity is predicted in saturated pure kaolinite samples, kaolinite suspension and shaly sandstone fairly well. Experimental results also showed that water interlay- ers play an important role in the compaction and strength of clay aggregates. Clay minerals carrying on water interlayers in their structure showed high compaction and strength. This study is relevant for a more reliable assessment of the seismic response in reservoirs and/or basins characterized by clay-bearing formations.

  10. Clay energetics in chemical evolution

    NASA Technical Reports Server (NTRS)

    Coyne, L. M.

    1986-01-01

    Clays have been implicated in the origin of terrestrial life since the 1950's. Originally they were considered agents which aid in selecting, concentrating and promoting oligomerization of the organic monomeric substituents of cellular life forms. However, more recently, it has been suggested that minerals, with particular emphasis on clays, may have played a yet more fundamental role. It has been suggested that clays are prototypic life forms in themselves and that they served as a template which directed the self-assembly of cellular life. If the clay-life theory is to have other than conceptual credibility, clays must be shown by experiment to execute the operations of cellular life, not only individually, but also in a sufficiently concerted manner as to produce some semblance of the functional attributes of living cells. Current studies are focussed on the ability of clays to absorb, store and transfer energy under plausible prebiotic conditions and to use this energy to drive chemistry of prebiotic relevance. Conclusions of the work are applicable to the role of clays either as substrates for organic chemistry, or in fueling their own life-mimetic processes.

  11. Tool for Taking Clay Impressions

    NASA Technical Reports Server (NTRS)

    Duncan, R. S.

    1984-01-01

    Clay impression of small parts taken with tool consisting of hollow tube closed at one end. Slots at other end admit part short distance into tube. Impression used to make silicone rubber mold for examination.

  12. Biodegradable pectin/clay aerogels.

    PubMed

    Chen, Hong-Bing; Chiou, Bor-Sen; Wang, Yu-Zhong; Schiraldi, David A

    2013-03-13

    Biodegradable, foamlike materials based on renewable pectin and sodium montmorillonite clay were fabricated through a simple, environmentally friendly freeze-drying process. The addition of multivalent cations (Ca(2+) and Al(3+)) resulted in apparent cross-linking of the polymer and enhancement of aerogel properties. The compressive properties increased as the solid contents (both pectin and clay) increased; moduli in the range of 0.04-114 MPa were obtained for materials with bulk densities ranging from 0.03 g/cm(3) to 0.19 g/cm(3), accompanied by microstructural changes from a lamellar structure to a cellular structure. Biodegradability of the aerogels was investigated by detecting CO2 release for 4 weeks in compost media. The results revealed that pectin aerogels possess higher biodegradation rates than wheat starch, which is often used as a standard for effective biodegradation. The addition of clay and multivalent cations surprisingly increased the biodegradation rates. PMID:23406325

  13. Boron Enrichment in Martian Clay

    PubMed Central

    Nagashima, Kazuhide; Freeland, Stephen J.

    2013-01-01

    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. PMID:23762242

  14. Boron enrichment in martian clay.

    PubMed

    Stephenson, James D; Hallis, Lydia J; Nagashima, Kazuhide; Freeland, Stephen J

    2013-01-01

    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. PMID:23762242

  15. Clay Mineralogy: The clay mineral composition of soils and clays is providing an understanding of their properties.

    PubMed

    Grim, R E

    1962-03-16

    The structures of the clay minerals are reasonably well known, but greater detail and more precision are needed if the properties of clays and soils are to be fully understood. For example, the selective adsorptive and catalytic properties and the reaction with organic materials vary with the character of the clay mineral, but the structural factors that control such properties are not well understood. Research is urgently needed on the structure of pure clay minerals and on the reactions of pure clay minerals with organic and inorganic materials. Much past research on clay-mineral reactions has little fundamental value because the clay that was used was composed of a mixture of minerals which were not well characterized. It is not a simple matter to find pure samples of many of the clay minerals, and to a considerable extent progress depends on finding such pure minerals or preparing them in the laboratory. PMID:17816101

  16. Picasso Masks: Cubism in Clay

    ERIC Educational Resources Information Center

    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…

  17. Biodegradable Pectin/clay Aerogels

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  18. Potassium hydroxide clay stabilization process

    SciTech Connect

    Sydansk, R.

    1981-07-28

    An aqueous solution having potassium hydroxide dissolved therein is injected into a subterranean sandstone formation containing water-sensitive fine particles, including clays. Potassium hydroxide stabilizes the fine particles for a substantial period of time thereby substantially preventing formation permeability damage caused by encroachment of aqueous solutions having a distinct ionic makeup into the treated formation.

  19. Amitriptyline removal using palygorskite clay.

    PubMed

    Tsai, Yo-Lin; Chang, Po-Hsiang; Gao, Zong-You; Xu, Xiao-Yuan; Chen, Yan-Hsin; Wang, Zheng-Hong; Chen, Xin-Yu; Yang, Zheng-Ying; Wang, Tzu-Hao; Jean, Jiin-Shuh; Li, Zhaohui; Jiang, Wei-Teh

    2016-07-01

    With the increased detections of commonly used pharmaceuticals in surface water and wastewater, extensive attentions were paid recently to the fate and transport of these pharmaceuticals in the environment. Amitriptyline (AMI) is a tricyclic antidepressant widely applied to treat patients with anxiety and depression. In this study, the removal of AMI with palygorskite clay (PFl-1) was investigated under different physico-chemical conditions and supplemented by instrumental analyses. The uptake of AMI on PFl-1 was well fitted by the Langmuir isotherm with an adsorption capacity of 0.168 mmol g(-1) at pH 6-7. The AMI uptake was fast and reached equilibrium in 15 min. The X-ray diffraction patterns showed no shift of the (110) peak position of palygorskite after AMI uptake. However, the (001) peak position of the minor component smectite (about 10%) shifted to lower angle as the amounts of AMI input increased. These results suggested surface uptake of AMI on palygorskite and interlayer uptake of AMI in smectite. As smectite is a common component of palygorskite clays, its role in assessing the properties and performances of palygorskite clays for the uptake and removal of contaminants should not be neglected. Overall, the high affinity of AMI for PFl-1 and strong retention of AMI on PFl-1 suggested that it could be a good adsorbent to remove AMI from wastewater. Palygorskite clays can also be a sink for many cationic pharmaceuticals in the environmental of the arid regions. PMID:27131449

  20. ADSORPTION OF SURFACTANT ON CLAYS

    EPA Science Inventory

    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...

  1. Stools - pale or clay-colored

    MedlinePlus

    ... gov/ency/article/003129.htm Stools - pale or clay-colored To use the sharing features on this page, please enable JavaScript. Stools that are pale, clay, or putty-colored may be due to problems ...

  2. Multifunctional epoxy composites with natural Moroccan clays

    NASA Astrophysics Data System (ADS)

    Monsif, M.; Zerouale, A.; Kandri, N. Idrissi; Allali, F.; Sgarbossa, P.; Bartolozzi, A.; Tamburini, S.; Bertani, R.

    2016-05-01

    Two natural Moroccan clays, here firstly completely characterized, have been used as fillers without modification in epoxy composites. Mechanical properties resulted to be improved and a significant antibacterial activity is exhibited by the epoxy composite containing the C2 clay.

  3. Adsorption of RDX on clay

    NASA Astrophysics Data System (ADS)

    Colon, Yleana M.; Alzate, Liliana F.; Ramos, Carmen M.; Santana, Alberto; Hernandez-Rivera, Samuel P.; Castro, Miguel E.; Munoz, Miguel; Mina, Nairmen

    2004-09-01

    The chemical spectroscopic signature of the RDX-clay mineral complex has been investigated by means of reflectance FT-IR micro spectroscopy. The mechanical analysis method was used to separate the clay from the other soil components. The soil was obtained from the University of Puerto Rico at Mayag'ez (UPRM) campus backyard. B3LYP/6-311G** calculations performed on RDX helped to determine the most stable conformations, their symmetry, and vibrational spectra. The FTIR technique confirmed the existence of two different RDX solid phases, known as the α-RDX and β-RDX, which have different symmetries and revealed significant differences in their spectra. The IR microspectroscopic study showed that the RDX-clay mineral complex and its interactions can be detected using the FTIR technique at a low concentration of 1000 part-per-millions. The results also suggest that the vibrational modes presenting changes in the different vibrational spectra correspond to the C-N and NO2 groups. In comparison with α-RDX spectrum, the complex exhibits three bands at 740, 754 and 792 cm-1. A 12 cm-1 red shift is observed in this last band assign to the C-N stretching and NO2 scissoring vibrations in the equatorial position. Differences in the spectra were also seen in the shifted bands at 942 and 953 cm-1. These vibrational modes are assigned to the ring breathing and N-N stretching vibration in the axial position for the -phase. Comparison of the spectra of the α-RDX, the β-RDX and the RDX mixed with clay in the range from 1190 to 1700 cm-1 clearly indicated that the FTIR technique can be used to study the interaction between RDX and clay. The results also indicate that the interaction between the RDX and the clay minerals affects mainly the NO2 groups of the explosive molecules. It is suggested that the electron donor nitrogen atoms from RDX are interacting with the electron acceptor oxygen atoms of the siloxane surface that is present in the majority of clays.

  4. 21 CFR 186.1256 - Clay (kaolin).

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Clay (kaolin). 186.1256 Section 186.1256 Food and... Substances Affirmed as GRAS § 186.1256 Clay (kaolin). (a) Clay (kaolin) Al2O3.2SiO2.nH2O, Cas Reg. No. 1332-58-7) consists of hydrated aluminum silicate. The commercial products of clay (kaolin)...

  5. 21 CFR 186.1256 - Clay (kaolin).

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Clay (kaolin). 186.1256 Section 186.1256 Food and....1256 Clay (kaolin). (a) Clay (kaolin) Al2O3.2SiO2.nH2O, Cas Reg. No. 1332-58-7) consists of hydrated aluminum silicate. The commercial products of clay (kaolin) contain varying quantities of alkalies...

  6. 21 CFR 186.1256 - Clay (kaolin).

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Clay (kaolin). 186.1256 Section 186.1256 Food and... Substances Affirmed as GRAS § 186.1256 Clay (kaolin). (a) Clay (kaolin) Al2O3.2SiO2.nH2O, Cas Reg. No. 1332-58-7) consists of hydrated aluminum silicate. The commercial products of clay (kaolin)...

  7. 21 CFR 186.1256 - Clay (kaolin).

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Clay (kaolin). 186.1256 Section 186.1256 Food and... Substances Affirmed as GRAS § 186.1256 Clay (kaolin). (a) Clay (kaolin) Al2O3.2SiO2.nH2O, Cas Reg. No. 1332-58-7) consists of hydrated aluminum silicate. The commercial products of clay (kaolin)...

  8. Mineral resource of the month: clays

    USGS Publications Warehouse

    Virta, Robert

    2004-01-01

    Clays represent one of the largest mineral commodities in the world in terms of mineral and rock production and use. Many people, however, do not recognize that clays are used in an amazingly wide variety of applications. Use continues to increase worldwide as populations and their associated needs increase. Robert Virta, clay and shale commodity specialist for the U.S. Geological Survey, has prepared the following information about clays.

  9. 21 CFR 186.1256 - Clay (kaolin).

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Clay (kaolin). 186.1256 Section 186.1256 Food and... Substances Affirmed as GRAS § 186.1256 Clay (kaolin). (a) Clay (kaolin) Al2O3.2SiO2.nH2O, Cas Reg. No. 1332-58-7) consists of hydrated aluminum silicate. The commercial products of clay (kaolin)...

  10. CLAY AND CLAY-SUPPORTED REAGENTS IN ORGANIC SYNTHESES: JOURNAL ARTICLE

    EPA Science Inventory

    NRMRL-CIN-0866 Varma*, R.S. Clay and Clay-Supported Reagents in Organic Syntheses. Tetrahedron (Sir J.E. Baldwin (Ed.), Elsevier Science Ltd) 58 (7):1235-1255 (2002). EPA/600/J-02/032. 10/28/1999 CLAY AND CLAY-SUPPORTED REAGENTS HAVE BEEN USED EXTENSIVELY FOR SYNTHETIC ORGA...

  11. Clay & Children: More than Making Pots.

    ERIC Educational Resources Information Center

    Kolbe, Ursula

    1997-01-01

    Working with clay enables young children to express, explore, and communicate their feelings and ideas. This resource booklet for early childhood practitioners and it promotes the clay table as a special place for shared discoveries, social interaction, and discussion. The booklet provides a glossary of terms used in clay work, as well as reasons…

  12. GEOSYNTHETIC CLAY LINERS (GCLS) IN LANDFILL COVERS

    EPA Science Inventory

    Low permeability, compacted clay linters are commonly required as a barrier to water infiltration in landfill covers. elatively new material, known as geosynthetic clay liner (GCL), has been proposed as an alternative to a compacted clay liner. CL has the practical advantages of ...

  13. Clay Cuffman: A Cool, Calm, Relaxed Guy

    ERIC Educational Resources Information Center

    Booth, Gina

    2010-01-01

    This article describes Clay Cuffman, a simple clay-sculpture project that requires two or three sessions, and works for students from the upper-elementary level through high school. It takes about 1.5 pounds of clay per student--about the size of a small grapefruit. The Cuffman project is a great way for upper-elementary through high-school…

  14. Clay-based Nanocomposites Possibilities and Limitations

    NASA Astrophysics Data System (ADS)

    Papoulis, Dimitris

    2011-09-01

    In the last decades, clay mineral based nanocomposites and polymer-clay nanocomposites (PCNC) have been proposed as very useful materials for many uses including photocatalysis, medicinal uses as tissue engineering or modified drug delivery systems. Clay minerals and especially montmorillonite, kaolinite, halloysite palygorskite and sepiolite are the most used clay minerals because of their high surface areas, colloidal dimensions of their particles and other properties. This lecture aims at reporting on very recent developments in the use of clay minerals and PCNC as materials with photocatalytic and medical interest.

  15. Contact micromechanics in granular media with clay

    SciTech Connect

    Ita, S.L.

    1994-08-01

    Many granular materials, including sedimentary rocks and soils, contain clay particles in the pores, grain contacts, or matrix. The amount and location of the clays and fluids can influence the mechanical and hydraulic properties of the granular material. This research investigated the mechanical effects of clay at grain-to-grain contacts in the presence of different fluids. Laboratory seismic wave propagation tests were conducted at ultrasonic frequencies using spherical glass beads coated with Montmorillonite clay (SWy-1) onto which different fluids were adsorbed. For all bead samples, seismic velocity increased and attenuation decreased as the contact stiffnesses increased with increasing stress demonstrating that grain contacts control seismic transmission in poorly consolidated and unconsolidated granular material. Coating the beads with clay added stiffness and introduced viscosity to the mechanical contact properties that increased the velocity and attenuation of the propagating seismic wave. Clay-fluid interactions were studied by allowing the clay coating to absorb water, ethyl alcohol, and hexadecane. Increasing water amounts initially increased seismic attenuation due to clay swelling at the contacts. Attenuation decreased for higher water amounts where the clay exceeded the plastic limit and was forced from the contact areas into the surrounding open pore space during sample consolidation. This work investigates how clay located at grain contacts affects the micromechanical, particularly seismic, behavior of granular materials. The need for this work is shown by a review of the effects of clays on seismic wave propagation, laboratory measurements of attenuation in granular media, and proposed mechanisms for attenuation in granular media.

  16. Modernity and putty-clay

    NASA Astrophysics Data System (ADS)

    Ganesh, Trichur Kailas

    This dissertation addresses issues arising out of the problems of capital accumulation, productivity growth and 'putty-clay' technology. The concept of economic modernity occupies a central place in the subject-matter studied here in that it expresses both the incessant drive for newness that characterizes economic reality and the persistence of dated techniques that successfully resist replacement. This study examines the way in which an expansive development-theoretic 'putty-clay' framework may be employed to explain the historical processes behind both the avalanche of newness (innovations) and the conservatism of technology in the U.S. economy. The guiding link is the fixity of investments in physical capital equipment over time and space. The dilemma of fixed capital is studied in the context of the constant entrepreneurial search for flexibility and liquidity. The thesis advanced is that a development (Entwicklung)-theoretic 'putty-clay' conceptualization of the economic system adequately addresses the recurring problems of fixity, flexibility, and liquidity, and thereby permits important insights into the enigma surrounding the persistent productivity growth slowdown and 'stagflation' of the late sixties and seventies and the related phenomena of physical 'capital obsolescence' and the financial or 'speculative explosions' of our times. The notion of 'putty-clay' used here is an innovative one in that it departs from the growth-theoretic literature to re-appear as a Schumpeterian theory of modernity modified by a Veblenite view of an economic system directed by the exigencies of the 'machine-process'. The empirical aptitude of a macroeconomic 'putty-clay' model to explain capital obsolescence mediated by the energy 'crises' (supply shocks) of the seventies and eighties is examined in a separate chapter with results that differ markedly from the standard (Berndt and Wood) conclusions for the U.S. economy. The final chapter in the dissertation reverts to the

  17. Mars, clays and the origins of life

    NASA Technical Reports Server (NTRS)

    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.

  18. Selective Clay Placement Within a Silicate-Clay Epoxy Blend Nanocomposite

    NASA Technical Reports Server (NTRS)

    Miller, Sandi G (Inventor)

    2013-01-01

    A clay-epoxy nanocomposite may be prepared by dispersing a layered clay in an alkoxy epoxy, such as a polypropylene oxide based epoxide before combining the mixture with an aromatic epoxy to improve the nanocomposite's thermal and mechanical properties.

  19. Iodide uptake by negatively charged clay interlayers?

    PubMed

    Miller, Andrew; Kruichak, Jessica; Mills, Melissa; Wang, Yifeng

    2015-09-01

    Understanding iodide interactions with clay minerals is critical to quantifying risk associated with nuclear waste disposal. Current thought assumes that iodide does not interact directly with clay minerals due to electrical repulsion between the iodide and the negatively charged clay layers. However, a growing body of work indicates a weak interaction between iodide and clays. The goal of this contribution is to report a conceptual model for iodide interaction with clays by considering clay mineral structures and emergent behaviors of chemical species in confined spaces. To approach the problem, a suite of clay minerals was used with varying degrees of isomorphic substitution, chemical composition, and mineral structure. Iodide uptake experiments were completed with each of these minerals in a range of swamping electrolyte identities (NaCl, NaBr, KCl) and concentrations. Iodide uptake behaviors form distinct trends with cation exchange capacity and mineral structure. These trends change substantially with electrolyte composition and concentration, but do not appear to be affected by solution pH. The experimental results suggest that iodide may directly interact with clays by forming ion-pairs (e.g., NaI(aq)) which may concentrate within the interlayer space as well as the thin areas surrounding the clay particle where water behavior is more structured relative to bulk water. Ion pairing and iodide concentration in these zones is probably driven by the reduced dielectric constant of water in confined space and by the relatively high polarizability of the iodide species. PMID:26057987

  20. Membrane behavior of clay liner materials

    NASA Astrophysics Data System (ADS)

    Kang, Jong Beom

    Membrane behavior represents the ability of porous media to restrict the migration of solutes, leading to the existence of chemico-osmosis, or the flow of liquid in response to a chemical concentration gradient. Membrane behavior is an important consideration with respect to clay soils with small pores and interactive electric diffuse double layers associated with individual particles, such as bentonite. The results of recent studies indicate the existence of membrane behavior in bentonite-based hydraulic barriers used in waste containment applications. Thus, measurement of the existence and magnitude of membrane behavior in such clay soils is becoming increasingly important. Accordingly, this research focused on evaluating the existence and magnitude of membrane behavior for three clay-based materials that typically are considered for use as liners for waste containment applications, such as landfills. The three clay-based liner materials included a commercially available geosynthetic clay liner (GCL) consisting of sodium bentonite sandwiched between two geotextiles, a compacted natural clay known locally as Nelson Farm Clay, and compacted NFC amended with 5% (dry wt.) of a sodium bentonite. The study also included the development and evaluation of a new flexible-wall cell for clay membrane testing that was used subsequently to measure the membrane behaviors of the three clay liner materials. The consolidation behavior of the GCL under isotropic states of stress also was evaluated as a preliminary step in the determination of the membrane behavior of the GCL under different effective consolidation stresses.

  1. Freeze-agglomeration: An alternative mechanism for clay film formation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Oriented clay coatings (argillans, clay cutans, clay films, lamellae) are often interpreted to be caused by illuviation (pervection, lessivage) of fine clay particles. In montane meadow soils (Typic Humaquepts) of the northern Sierra Nevada Range, prominent clay cutans occur on ped faces of a paleos...

  2. Clay Corner: Light up a Turkey.

    ERIC Educational Resources Information Center

    Hiller, Peter

    1998-01-01

    Presents two activities that enable students to work with clay: a tile project and turkey candle-holders. Explains that before students actually create their own projects, they get an opportunity to experience the clay itself. Asserts that the new vocabulary, unusual equipment, and intriguing techniques make ceramics a motivating activity. (CMK)

  3. Clay smear: Review of mechanisms and applications

    NASA Astrophysics Data System (ADS)

    Vrolijk, Peter J.; Urai, Janos L.; Kettermann, Michael

    2016-05-01

    Clay smear is a collection of fault processes and resulting fault structures that form when normal faults deform layered sedimentary sections. These elusive structures have attracted deep interest from researchers interested in subsurface fluid flow, particularly in the oil and gas industry. In the four decades since the association between clay-smear structures and oil and gas accumulations was introduced, there has been extensive research into the fault processes that create clay smear and the resulting effects of that clay smear on fluid flow. We undertake a critical review of the literature associated with outcrop studies, laboratory and numerical modeling, and subsurface field studies of clay smear and propose a comprehensive summary that encompasses all of these elements. Important fault processes that contribute to clay smear are defined in the context of the ratio of rock strength and in situ effective stresses, the geometric evolution of fault systems, and the composition of the faulted section. We find that although there has been progress in all avenues pursued, progress has been uneven, and the processes that disrupt clay smears are mostly overlooked. We highlight those research areas that we think will yield the greatest benefit and suggest that taking these emerging results within a more process-based framework presented here will lead to a new generation of clay smear models.

  4. Dehydration-induced luminescence in clay minerals

    NASA Technical Reports Server (NTRS)

    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.

  5. Desert varnish: the importance of clay minerals.

    PubMed

    Potter, R M; Rossman, G R

    1977-06-24

    Desert varnish has been characterized by infrared spectroscopy, x-ray diffraction, and electron microscopy. It is a distinct morphological entity having an abrupt boundary with the underlying rock. Clay minerals comprise more than 70 percent of the varnish. Iron and manganese oxides constitute the bulk of the remainder and are dispersed throughout the clay layer. PMID:17776923

  6. Sectioning Clay Models Makes Anatomy & Development Tangible

    ERIC Educational Resources Information Center

    Howell, Carina Endres; Howell, James Endres

    2010-01-01

    Clay models have proved to be useful teaching aids for many topics in biology that depend on three-dimensional reasoning. Students studying embryonic development struggle to mentally reconstruct the three-dimensional structure of embryos and larvae by observing prepared slides of cross-sectional slices. Students who build clay models of embryos…

  7. The colloidal chemistry of ceramic clays

    NASA Technical Reports Server (NTRS)

    Phelps, G. W.

    1984-01-01

    The colloidal chemistry and mineralogy of two argil minerals were studied. Deposits of kaolin and of ceramic clays in the United States and England are discussed for the probable mechanism of formation. The structural modifications of the bed, original material associated with the clays and the proper use of flocculants are discussed.

  8. Clays and other minerals in prebiotic processes

    NASA Technical Reports Server (NTRS)

    Paecht-Horowitz, M.

    1984-01-01

    Clays and other minerals have been investigated in context with prebiotic processes, mainly in polymerization of amino acids. It was found that peptides adsorbed on the clay, prior to polymerization, influence the reaction. The ratio between the amount of the peptides adsorbed and that of the clay is important for the yield as well as for the degrees of polymerization obtained. Adsorption prior to reaction produces a certain order in the aggregates of the clay particles which might induce better reaction results. Excess of added peptides disturbs this order and causes lesser degrees of polymerization. In addition to adsorption, clays are also able to occlude between their layers substances out of the environment, up to very high concentrations.

  9. Active containment systems incorporating modified pillared clays

    SciTech Connect

    Lundie, P. |; McLeod, N.

    1997-12-31

    The application of treatment technologies in active containment systems provides a more advanced and effective method for the remediation of contaminated sites. These treatment technologies can be applied in permeable reactive walls and/or funnel and gate systems. The application of modified pillared clays in active containment systems provides a mechanism for producing permeable reactive walls with versatile properties. These pillared clays are suitably modified to incorporate reactive intercalatants capable of reacting with both a broad range of organic pollutants of varying molecular size, polarity and reactivity. Heavy metals can be removed from contaminated water by conventional ion-exchange and other reactive processes within the clay structure. Complex contamination problems can be addressed by the application of more than one modified clay on a site specific basis. This paper briefly describes the active containment system and the structure/chemistry of the modified pillared clay technology, illustrating potential applications of the in-situ treatment process for contaminated site remediation.

  10. Preconsolidation versus aging behavior of kaolinite clay

    SciTech Connect

    Athanasopoulos, G.A. )

    1993-06-01

    Results of resonant column tests were used to determine the effects of overconsolidation ratio (OCR) and of aging on the normalized rate of secondary increase N[sub G] of low-amplitude shear modulus G[sub 0] of a remolded kaolinite clay. The value of N[sub G] decreased approximately linearly with the logarithm of OCR and with the logarithm of duration of aging of the clay. The similarity of behavior provided a basis for establishing an equivalency between age-and-stress-induced equivalent overconsolidation for the clay in question. It was concluded that up to a certain limiting duration of aging the age-induced OCR increases linearly with elapsed time, whereas the effect starts diminishing for longer durations of aging. It is suggested that the results of similar studies on natural clay soils be used for predicting the long-term behavior of clays from the results of short-duration tests.

  11. Phosphates in some missouri refractory clays

    USGS Publications Warehouse

    Hall, R.B.; Foord, E.E.; Keller, D.J.; Keller, W.D.

    1997-01-01

    This paper describes in detail phosphate minerals occurring in refractory clays of Missouri and their effect on the refractory degree of the clays. The minerals identified include carbonate-fluorapatite (francolite), crandallite, goyazite, wavellite, variscite and strengite. It is emphasized that these phosphates occur only in local isolated concentrations, and not generally in Missouri refractory clays. The Missouri fireclay region comprises 2 districts, northern and southern, separated by the Missouri River In this region, clay constitutes a major part of the Lower Pennsylvanian Cheltenham Formation. The original Cheltenham mud was an argillic residue derived from leaching and dissolution of pre-Pennsylvanian carbonates. The mud accumulated on a karstic erosion surface truncating the pre-Cheltenham rocks. Fireclays of the northern district consist mainly of poorly ordered kaolinite, with variable but minor amounts of illite, chlorite and fine-grained detrital quartz. Clays of the southern district were subjected to extreme leaching that produced well-ordered kaolinite flint clays. Local desilication formed pockets of diaspora, or more commonly, kaolinite, with oolite-like nubs or burls of diaspore ("burley" clay). The phosphate-bearing materials have been studied by X-ray diffraction (XRD), scanning electron microscopy-energy dispersive spectral analysis (SEM-EDS) and chemical analysis. Calcian goyazite was identified in a sample of diaspore, and francolite in a sample of flint clay. A veinlet of wavellite occurs in flint clay at one locality, and a veinlet of variscite-strengite at another locality. The Missouri flint-clay-hosted francolite could not have formed in the same manner as marine francolite The evidence suggests that the Cheltenham francolite precipitated from ion complexes in pore water nearly simultaneously with crystallization of kaolinite flint clay from an alumina-silica gel. Calcian goyazite is an early diagenetic addition to its diaspore host

  12. Fine particle clay catalysts for coal liquefaction

    SciTech Connect

    Olson, E.S.

    1991-01-01

    The efficient production of environmentally acceptable distillate fuels requires catalysts for hydrogenation and cleavage of the coal macromolecules and removal of oxygen, nitrogen, and sulfur heteroatoms. The goal of the proposed research is to develop new catalysts for the direct liquefaction of coal. This type of catalyst consists of fine clay particles that have been treated with reagents which form pillaring structures between the aluminosilicate layers of the clay. The pillars not only hold the layers apart but also constitute the active catalytic sites for hydrogenation of the coal and the solvent used in the liquefaction. The pillaring catalytic sites are composed of pyrrhotite, which has been previously demonstrated to be active for coal liquefaction. The pyrrhotite sites are generated in situ by sulfiding the corresponding oxyiron species. The size of the catalyst will be less than 40 nm in order to promote intimate contact with the coal material. Since the clays and reagents for pillaring and activating the clays are inexpensive, the catalysts can be discarded after use, rather than regenerated by a costly process. The proposed work will evaluate methods for preparing the fine particle iron-pillared clay dispersions and for activating the particles to generate the catalysts. Characterization studies of the pillared clays and activated catalysts will be performed. The effectiveness of the pillared clay dispersion for hydrogenation and coal liquefaction will be determined in several types of testing.

  13. Fine particle clay catalysts for coal liquefaction

    SciTech Connect

    Olson, E.S.

    1991-01-01

    The efficient production of environmentally acceptable distillate fuels requires catalysts for hydrogenation and cleavage of the coal macromolecules and removal of oxygen, nitrogen, and sulfur heteroatoms. The goal of the proposed research is to develop new catalysts for the direct liquefaction of coal. This type of catalyst consists of fine clay particles that have been treated with reagents which form pillaring structures between the aluminosilicate layers of the clay. The pillars not only hold the layers apart but also constitute the active catalytic sites for hydrogenation of the coal and solvent used in the liquefaction. The pillaring catalytic sites are composed of pyrrhotite, which has been previously demonstrated to be active for coal liquefaction. The pyrrhotite sites are generated in situ by sulfiding the corresponding oxyiron species. The size of the catalyst will be less than 40 nm in order to promote intimate contact with the coal material. Since the clays and reagents for pillaring and activating the clays are inexpensive, the catalysts can be discarded after use, rather than regenerated by a costly process. The proposed work will evaluate methods for preparing the fine particle iron-pillared clay dispersions and for activating the particles to generate the catalysts. Characterization studies of the pillared clays and activated catalysts will performed. The effectiveness of the pillared clay dispersion for hydrogenation and coal liquefaction will be determined in several types of testing. 5 refs., 1 tab.

  14. Discrete Analysis of Clay Layer Tensile Strength

    NASA Astrophysics Data System (ADS)

    Lê, T. N. H.; Plé, O.; Villard, P.; Gotteland, P.; Gourc, J. P.

    2009-06-01

    The Discrete Element Method is used to investigate the tensile behaviour and cracks mechanisms of a clay material submitted to bending loading. It is the case of compacted clay liners in landfill cap cover application. Such as the soil tested in this study is plastic clay, the distinct elements model was calibrated with previous data results by taking into account cohesive properties. Various contact and cohesion laws are tested to show that the numerical model is able to reproduce the failure mechanism. Numerical results are extending to simulate a landfill cap cover.

  15. Water sites at a clay interface

    SciTech Connect

    Grandjean, J.

    1997-01-15

    Aqueous suspensions of swelling clays (smectites) find uses in many industrial applications including drilling fluids, suspending agents and water treatment. {sup 2}H NMR quadrupolar splittings of clay suspensions monitor the orientation of water molecules near the solid surface. Two limiting water interfacial sites explain the results on montmorillonite, hectorite, and saponite suspensions. The location of cation isomorphous substitution and the Ca{sup 2+}/Na{sup +} molar ratio of exchangeable cations modulate their relative importance. With beidellite suspensions, water orientation at the clay surface cannot be described within the above scheme.

  16. Natural Radioactivity of Boron Added Clay Samples

    NASA Astrophysics Data System (ADS)

    Akkurt, I.; ćanakciı, H.; Mavi, B.; Günoǧlu, K.

    2011-12-01

    Clay, consisting fine-grained minerals, is an interesting materials and can be used in a variety of diferent fields especially in dermatology application. Using clay such a field it is important to measure its natural radioacitivty. Thus the purpose of this study is to measure 226Ra, 232Th and 40K concentration in clay samples enriched with boron. Three different types of clay samples were prepared where boron is used in different rate. The measurements have been determined using a gamma-ray spectrometry consists of a 3″×3″ NaI(Tl) detector. From the measured activity the radium equivalent activities (Raeq), external hazard index (Hex), absorbed dose rate in air (D) and annual effective dose (AED) have also been obtained.

  17. Stools - pale or clay-colored

    MedlinePlus

    Possible causes for clay-colored stools include: Alcoholic hepatitis Biliary cirrhosis Cancer or noncancerous (benign) tumors of the liver, biliary system, or pancreas Cysts of the bile ducts Gallstones Medications Narrowings (strictures) of the ...

  18. Polarographic reduction behaviour of clay minerals.

    PubMed

    Malik, W U; Gupta, G C

    1968-01-01

    Suspensions of the clay minerals bentonite, kaolinite illite and chlorite have been examined polarographically and reduction waves found. The differences in their behaviour, with and without the addition of surface active reagents, are reported. PMID:18960257

  19. Natural Radioactivity of Boron Added Clay Samples

    SciTech Connect

    Akkurt, I.; Guenoglu, K.; Canakcii, H.; Mavi, B.

    2011-12-26

    Clay, consisting fine-grained minerals, is an interesting materials and can be used in a variety of different fields especially in dermatology application. Using clay such a field it is important to measure its natural radioactivity. Thus the purpose of this study is to measure {sup 226}Ra, {sup 232}Th and {sup 40}K concentration in clay samples enriched with boron. Three different types of clay samples were prepared where boron is used in different rate. The measurements have been determined using a gamma-ray spectrometry consists of a 3''x3'' NaI(Tl) detector. From the measured activity the radium equivalent activities (Ra{sub eq}), external hazard index (H{sub ex}), absorbed dose rate in air (D) and annual effective dose (AED) have also been obtained.

  20. Clay-Bacteria Systems and Biofilm Production

    NASA Astrophysics Data System (ADS)

    Steiner, J.; Alimova, A.; Katz, A.; Steiner, N.; Rudolph, E.; Gottlieb, P.

    2007-12-01

    Soil clots and the aerosol transport of bacteria and spores are promoted by the formation of biofilms (bacteria cells in an extracellular polymeric matrix). Biofilms protect microorganisms by promoting adhesion to both organic and inorganic surfaces. Time series experiments on bacteria-clay suspensions demonstrate that biofilm growth is catalyzed by the presence of hectorite in minimal growth media for the studied species: Gram negatives (Pseudomonas syringae and Escherichia coli,) and Gram positives (Staphylococcus aureus and Bacillus subtilis). Soil organisms (P. syringae, B. subtilis) and organisms found in the human population (E. coli, S. aureus) are both used to demonstrate the general applicability of clay involvement. Fluorescent images of the biofilms are acquired by staining with propidium iodide, a component of the BacLightTM Live/Dead bacterial viability staining kit (Molecular Probes, Eugene, OR). The evolving polysaccharide-rich biofilm reacts with the clay interlayer site causing a complex substitution of the two-water hectorite interlayer with polysaccharide. The result is often a three-peak composite of the (001) x-ray diffraction maxima resulting from polysaccharide-expanded clays and an organic-driven contraction of a subset of the clays in the reaction medium. X-ray diffractograms reveal that the expanded set creates a broad maximum with clay subsets at 1.84 nm and 1.41 nm interlayer spacings as approximated by a least squares double Lorentzian fit, and a smaller shoulder at larger 2q, deriving from a contraction of the interlayer spacing. Washing with chlorox removes organic material from the contracted clay and creates a 1-water hectorite single peak in place of the double peak. The clay response can be used as an indirect indicator of biofilm in an environmental system.

  1. Clay-mediated reactions of HCN oligomers - The effect of the oxidation state of the clay

    NASA Technical Reports Server (NTRS)

    Ferris, J. P.; Alwis, K. W.; Edelson, E. H.; Mount, N.; Hagan, W. J., Jr.

    1981-01-01

    Montmorillonite clays which contain Fe(III) inhibit the oligomerization of aqueous solutions of HCN. The inhibitory effect is due to the rapid oxidation of diaminomaleonitrile, a key intermediate in HCN oligomerization, by the Fe(III) incorporated into the aluminosilicate lattice of the clay. The Fe(III) oxidizes diaminomaleonitrile to diiminosuccinonitrile, a compound which is rapidly hydrolyzed to HCN and oxalic acid derivatives. Diaminomaleonitrile is not oxidized when Fe(III) in the montmorillonite is reduced with hydrazine. The oxidation state of the clay is an important variable in experiments designed to simulate clay catalysis on the primitive earth.

  2. Magnetic theoretical and experimental study of clays for petroleum reservoir clay typing

    NASA Astrophysics Data System (ADS)

    Ivakhnenko, Aleksandr; Makarova, Maria; Telman, Meruert

    2013-04-01

    This study describes theoretical and experimental magnetic analysis of different clay types for petroleum reservoir characterisation by using low and high field magnetic susceptibility. Most clays for example, saponite, clay loam and bentonite are paramagnetic, whereas some clays (kaolinite) and matrix minerals such as quartz and calcite are diamagnetic. Model magnetic susceptibility and magnetic hysteresis plots for various concentrations of different clays in quartz matrix were initially calculated. Experimental magnetic measurements were undertaken for comparison on a series of synthetic reservoir samples comprising various concentrations of dispersed clays in a quartz matrix. The experimental magnetic measurements showed substantial agreement with the model magnetic values, and with estimates of the magnetic susceptibility based on low and high field magnetic susceptibility for derived mineral contents. Importantly different magnetic parameters, including IRM (isothermal remnant magnetisation) were determined for the different clay types and their mixtures with the sandstone rock matrix, together with given permeability variations in the samples. Results demonstrate that these magnetic measurements potentially provide a sensitive, rapid, quantitative technique which can be used for petrophysical analysis of clay-rich rocks and clay typing.

  3. Soil clay content underlies prion infection odds

    USGS Publications Warehouse

    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.

  4. What Makes a Natural Clay Antibacterial?

    PubMed Central

    Williams, Lynda B.; Metge, David W.; Eberl, Dennis D.; Harvey, Ronald W.; Turner, Amanda G.; Prapaipong, Panjai; Poret-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 (<200 nm), illite-smectite and reduced iron phases. The role of clay minerals in the bactericidal process is to buffer the aqueous pH and oxidation state to conditions that promote Fe2+ solubility. Chemical analyses of E. coli killed by aqueous leachates of an antibacterial clay show that intracellular concentrations of Fe and P are elevated relative to controls. Phosphorus uptake by the cells supports a regulatory role of polyphosphate or phospholipids in controlling Fe2+. Fenton reaction products can degrade critical cell components, but we deduce that extracellular processes do not cause cell death. Rather, Fe2+ overwhelms outer membrane regulatory proteins and is oxidized when it enters the cell, precipitating Fe3+ and producing lethal hydroxyl radicals. PMID:21413758

  5. A clay grouting technique for granitic rock adjacent to clay bulkhead

    NASA Astrophysics Data System (ADS)

    Masumoto, K.; Sugita, Y.; Fujita, T.; Martino, J. B.; Kozak, E. T.; Dixon, D. A.

    Excavation and re-distribution of the stress around the tunnel lead to the development of an excavation damage zone (EDZ). While the bulkheads are keyed into the rock wall of the tunnel to act as cut-offs for the EDZ of the tunnel, clay grouting was conducted around the clay bulkhead as an additional measure to interrupt the connectivity of EDZ at the bulkhead. Clay grouting is being tested to determine if it is an effective method to reduce the permeability of fractured rock. The grouting into the EDZ is difficult because many of the fractures in the EDZ are connected with the excavation surface and cannot be filled efficiently by pressurizing the grout slurry. Therefore, the in situ injection tests of the clay grouting technique for the EDZ adjacent to the clay bulkhead were conducted to demonstrate the clay grouting technique and to estimate the ability of clay grouting to reduce permeability in the EDZ. This paper presents the results of these tests. Three in situ tests of clay grouting were performed during the Tunnel Sealing Experiment (TSX), conducted at Canada’s Underground Research Laboratory (URL) in the granitic rock to demonstrate technologies for tunnel sealing at full-scale. First, a clay grouting trial was conducted at a trial key in the tunnel about 25 m above the TSX tunnel. Secondly, the two series of clay grouting were performed in the TSX tunnel, on the upstream face of the key prior to the installation of the seal material of the clay key and later on the downstream side of the bulkhead. The results of these tests indicated a reduction in the permeability of granitic rock around the holes after grouting.

  6. NMR imaging and cryoporometry of swelling clays

    NASA Astrophysics Data System (ADS)

    Dvinskikh, Sergey V.; Szutkowski, Kosma; Petrov, Oleg V.; Furó, István.

    2010-05-01

    Compacted bentonite clay is currently attracting attention as a promising "self-sealing" buffer material to build in-ground barriers for the encapsulation of radioactive waste. It is expected to fill up the space between waste canister and surrounding ground by swelling and thus delay flow and migration from the host rock to the canister. In environmental sciences, evaluation and understanding of the swelling properties of pre-compacted clay are of uttermost importance for designing such buffers. Major goal of present study was to provide, in a non-invasive manner, a quantitative measure of bentonite distribution in extended samples during different physical processes in an aqueous environment such as swelling, dissolution, and sedimentation on the time scale from minutes to years. The propagation of the swelling front during clay expansion depending on the geometry of the confining space was also studied. Magnetic resonance imaging and nuclear magnetic resonance spectroscopy were adapted and used as main experimental techniques. With this approach, spatially resolved movement of the clay/water interface as well as clay particle distributions in gel phase can be monitored [1]. Bulk samples with swelling in a vertical tube and in a horizontal channel were investigated and clay content distribution profiles in the concentration range over five orders of magnitude and with sub-millimetre spatial resolution were obtained. Expansion rates for bulk swelling and swelling in narrow slits were compared. For sodium-exchanged montmorillonite in contact with de-ionised water, we observed a remarkable acceleration of expansion as compared to that obtained in the bulk. To characterize the porosity of the clay a cryoporometric study [2] has been performed. Our results have important implications to waste repository designs and for the assessment of its long-term performance. Further research exploring clay-water interaction over a wide variety of clay composition and water ionic

  7. Clay Minerals are controlled by the environment - Clay Minerals control the environment

    NASA Astrophysics Data System (ADS)

    Stahr, K.; Zarei, M.

    2012-04-01

    Where clay minerals are analyzed in soils, often there is some confusion, because in the widespread loess-affected and moraine landscapes of Europe quite a variety of clay minerals is found. The sources of these minerals are inherited from the local solid rock, transported through different processes, transformed through mineral changes and inherited from paleo-environments. Very often a miserable assemblage in the clay fraction is found with mica clay, smectite, kaolinite, chlorite and also some quartz. In order to understand the current dynamic of clay mineral formation, very detailed and quantitative analysis in comparison of horizons and landscape are necessary. It is much easier to through light on the development, if conditions are looked for where a single specific mineral can be formed like short range order minerals from volcanic ashes or smectites from basaltic parent material. Old leaching land surfaces will form kaolinitic and in tropical areas gibbsitic clay fractions. In arid environments of deserts and desert fringes, palygorskite and sepiolite can dominate. In general, clay minerals buffer the environment. This is mainly due to the extraordinary large interfaces between mineral surface and pore systems. In the last years mainly the processes of buffering through charging soil solution and of buffering through mineral organic compounds have been analyzed. Development of new microscopic and spectromethods have brought great progress in understanding the role of clays in soil environments.

  8. Clay mineralogy of weathering rinds and possible implications concerning the sources of clay minerals in soils.

    USGS Publications Warehouse

    Colman, Steven M.

    1982-01-01

    Weathering rinds on volcanic clasts in Quaternary deposits in the western US contain only very fine-grained and poorly crystalline clay minerals. Rinds were sampled from soils containing well-developed argillic B horizons in deposits approx 105 yr old or more. The clay-size fraction of the rinds is dominated by allophane and iron hydroxy-oxides, whereas the B horizons contain abundant well-crystallized clay minerals. The contrast between the clay mineralogy of the weathering rinds, in which weathering is isolated from other soil processes, and that of the associated soil matrices suggests a need to reassess assumptions concerning the rates at which clay minerals form and the sources of clay minerals in argillic B horizons. It seems that crystalline clay minerals form more slowly in weathering rinds than is generally assumed for soil environments and that the weathering of primary minerals may not be the dominant source of crystalline clay minerals in Middle to Late Pleistocene soil.-A.P.

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

    SciTech Connect

    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.

  10. Organic or organometallic template mediated clay synthesis

    SciTech Connect

    Gregar, K.C.; Winans, R.E.; Botto, R.E.

    1992-12-31

    A method is given for incorporating diverse varieties of intercalants or templates directly during hydrothermal synthesis of clays such as hectorite or montmorillonite-type layer-silicate clays. For a hectorite layer-silicate clay, refluxing a gel of silica sol, magnesium hydroxide sol and LiF for 2 days with an organic or organometallic intercalant or template results in crystalline products containing either (a) organic dye molecules such as ethyl violet and methyl green, (b) dye molecules such as alcian blue based on a Cu(II)-phthalocyannine complex, or (c) transition metal complexes such as Ru(II)phenanthroline and Co(III)sepulchrate or (d) water-soluble porphyrins and metalloporphyrins. Montmorillonite-type clays are made by the method taught by US patent No. 3,887,454 issued to Hickson, June 13, 1975; however, a variety of intercalants or templates may be introduced. The intercalants or templates should have water-solubility, positive charge, and thermal stability under moderately basic (pH 9-10) aqueous reflux conditions or hydrothermal pressurized conditions for the montmorillonite-type clays.

  11. Organic or organometallic template mediated clay synthesis

    DOEpatents

    Gregar, K.C.; Winans, R.E.; Botto, R.E.

    1994-05-03

    A method is described for incorporating diverse varieties of intercalates or templates directly during hydrothermal synthesis of clays such as hectorite or montmorillonite-type layer-silicate clays. For a hectorite layer-silicate clay, refluxing a gel of silica sol, magnesium hydroxide sol and lithium fluoride for two days in the presence of an organic or organometallic intercalate or template results in crystalline products containing either (a) organic dye molecules such as ethyl violet and methyl green, (b) dye molecules such as alcian blue that are based on a Cu(II)-phthalocyannine complex, or (c) transition metal complexes such as Ru(II)phenanthroline and Co(III)sepulchrate or (d) water-soluble porphyrins and metalloporphyrins. Montmorillonite-type clays are made by the method taught by U.S. Pat. No. 3,887,454 issued to Hickson, Jun. 13, 1975; however, a variety of intercalates or templates may be introduced. The intercalates or templates should have (i) water-solubility, (ii) positive charge, and (iii) thermal stability under moderately basic (pH 9-10) aqueous reflux conditions or hydrothermal pressurized conditions for the montmorillonite-type clays. 22 figures.

  12. Organic or organometallic template mediated clay synthesis

    DOEpatents

    Gregar, Kathleen C.; Winans, Randall E.; Botto, Robert E.

    1994-01-01

    A method for incorporating diverse Varieties of intercalants or templates directly during hydrothermal synthesis of clays such as hectorite or montmorillonite-type layer-silicate clays. For a hectorite layer-silicate clay, refluxing a gel of silica sol, magnesium hydroxide sol and lithium fluoride for two days in the presence of an organic or organometallic intercalant or template results in crystalline products containing either (a) organic dye molecules such as ethyl violet and methyl green, (b) dye molecules such as alcian blue that are based on a Cu(II)-phthalocyannine complex, or (c) transition metal complexes such as Ru(II)phenanthroline and Co(III)sepulchrate or (d) water-soluble porphyrins and metalloporphyrins. Montmorillonite-type clays are made by the method taught by U.S. Pat. No. 3,887,454 issued to Hickson, Jun. 13, 1975; however, a variety of intercalants or templates may be introduced. The intercalants or templates should have (i) water-solubility, (ii) positive charge, and (iii) thermal stability under moderately basic (pH 9-10) aqueous reflux conditions or hydrothermal pressurized conditions for the montmorillonite-type clays.

  13. Mineral Acquisition from Clay by Budongo Forest Chimpanzees

    PubMed Central

    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. PMID:26218593

  14. Polymer based nanocomposites with nanofibers and exfoliated clay

    NASA Technical Reports Server (NTRS)

    Meador, Michael A.; Reneker, Darrell H.

    2005-01-01

    Polymer solutions, containing clay sheets, were electrospun into nanofibers and microfibers that contained clay sheets inside. Controllable removal of polymer by plasma etching from the surface of fibers revealed the arrangement of clay. The shape, flexibility, size distribution and arrangement of clay sheets were observed by transmission and scanning electron microscopy. The clay sheets were partially aligned in big fibers with normal direction of clay sheets perpendicular to fiber axis. Crumpling of clay sheets inside fibers was observed when the fiber diameter was comparable to the lateral size of clay sheets. Single sheets of clay were observed both by catching clay sheets dispersed in water with electrospun nanofiber mats and by the deliberate removal of most of the polymer in the fibers. Thin, flexible gas barrier films, that are reasonably strong, were assembled from clay sheets and polymer nanofibers. Structure of composite films was characterized with scanning electron microscopy. Continuous film of clay sheets were physically attached to the surface of fiber mats. Spincoating film of polymer and clay sheets was reinforced by electrospun fiber scaffold. Certain alignment of clay sheets was observed in the vicinity of fibers.

  15. Interaction of polymer with discotic clay particles.

    SciTech Connect

    Auvray, L.; Lal, J.

    1999-08-04

    Normally synthetic well defined monodisperse discotic laponite clays are known to form a gel phase at mass concentrations as low as a few percent in distilled water. Hydrosoluble polymer polyethylene oxide was added to this intriguing clay system, it was observed that it either prevents gelation or slows it down extremely depending on the polymer weight, concentration or the laponite concentration. Small Angle Neutron scattering (SANS) was used to study these systems because only by isotopic labeling can the structure of the adsorbed polymer layers be determined. The contrast variation technique is specifically used to determine separately the different partial structure factors of the clay and polymer. In this way the signal of the adsorbed chains is separated from the signal of the free chains in the dilute regime. Attempts have also been made to characterize the structure in the concentrated regime of laponite with polymer.

  16. Effect of aging on rheology of ball clay suspensions

    NASA Astrophysics Data System (ADS)

    Tonthai, Tienchai

    2002-01-01

    The behaviors of clay-water suspensions such as deflocculation or rheological properties are not constant but change with time. Aging has been recognized for changing the rheological properties of clay suspensions. This work provided information about the effects of the moisture contents in ball clay lumps and clay air exposure time on their processability. Dynamic oscillatory rheometry using a vane-in-cup geometry was used to characterize the rheological behavior of ball clay suspensions in terms of elastic modulus, viscous modulus and yield stress as a function of aging time. A light scattering size analyzer was used to examine the agglomerate size distribution of ball clay suspensions which affected the rheological behavior. Soluble ion release (both cations and anions) in the filtrate of suspensions was measured by ion chromatography. Low and high lignitic ball clay suspensions were dispersed with sodium silicate (Na2SiO3) or sodium polyacrylate at specific gravity 1.3 and 1.6 in two dispersion states: fully deflocculated (minimum viscosity) and under deflocculated. Suspensions prepared using freshly mined ball clays required more dispersant than suspensions prepared using dry ball clays to achieve minimum viscosity due to a difference in agglomerate size distribution. The agglomerate size distribution of suspensions prepared using dry clays was broader than that of suspensions prepared using freshly mined clays. In suspensions prepared using freshly mined clays, there were many uniformly small agglomerates having loose water inside, while in suspensions prepared using dry clays, the capillary effect and bonding between clay particles resulting from drying broke clay aggregates apart into agglomerate structures composed of a few to many clay particles. For suspensions prepared using dry clays after one day suspension aging, the elastic modulus and yield stress decreased due to the change in agglomerate size distribution of suspensions but increased for

  17. Radiocarbon Ages of Postglacial Lake Clays near Michigan City, Indiana.

    PubMed

    Winkler, E M

    1962-08-17

    Two radiocarbon dates were obtained for postglacial clays. One sample, 6350 years old, was taken from a bed of compacted and carbonized wood just above a bed of pebbly clay. Overlying the woody bed is 5(1/2) feet of organic bluish clays and beach sands near the present lake level. The upper clay layer contained a younger wood sample, 5475 years old. The blue clays are of shallow swamp origin and were deposited during the late low-water stage of Lake Chippewa; the pebbly clay is assumed to be of Glenwood age (about 11,000 years) or older. PMID:17749630

  18. Chlorination of alumina in kaolinitic clay

    NASA Astrophysics Data System (ADS)

    Grob, B.; Richarz, W.

    1984-09-01

    The chlorination of alumina in kaolinitic clay with Cl2 and CO gas mixtures was studied gravimetrically. The effects of the calcination method and of NaCl addition on the reactivity of the clay were examined. Fast reaction rates were achieved only with samples previously exposed to a sulfating treatment. Optimum conditions, with maximum yield and selectivity to A1C13 and minimum SiO2 conversion, were found between 770 and 970 K. At higher temperatures the SiCl4 formed poisons the reactive alumina surface by selective chemisorption with a marked decrease of the reaction rate.

  19. Ostwald ripening of clays and metamorphic minerals

    USGS Publications Warehouse

    Eberl, D.D.; Srodon, J.; Kralik, M.; Taylor, B.E.; Peterman, Z.E.

    1990-01-01

    Analyses of particle size distributions indicate that clay minerals and other diagenetic and metamorphic minerals commonly undergo recrystallization by Ostwald ripening. The shapes of their particle size distributions can yield the rate law for this process. One consequence of Ostwald ripening is that a record of the recrystallization process is preserved in the various particle sizes. Therefore, one can determine the detailed geologic history of clays and other recrystallized minerals by separating, from a single sample, the various particle sizes for independent chemical, structural, and isotopic analyses.

  20. Numerical Modelling of Embankment on Soft Clay

    NASA Astrophysics Data System (ADS)

    Nujid, M. M.; Taha, M. R.

    2016-07-01

    This paper aims to predict deformation of embankment on soft clay of Muar. The prediction performance focusing on displacement at critical fill height of 5.5 m. The study was based on reported result in 1992. With the aid of computer intelligence, the advanced constitutive soil models could be adopted to analyze the soft clay behavior. The COMSOL Multiphysics (v4.4) has been used to simulate the problem with coupled physics available in the software. The vertical displacements are in good agreement close to published result.

  1. Reducing the Cation Exchange Capacity of Lithium Clay to Form Better Dispersed Polymer-Clay Nanocomposites

    NASA Technical Reports Server (NTRS)

    Liang, Maggie

    2004-01-01

    Polymer-clay nanocomposites have exhibited superior strength and thermo- oxidative properties as compared to pure polymers for use in air and space craft; however, there has often been difficulty completely dispersing the clay within the matrices of the polymer. In order to improve this process, the cation exchange capacity of lithium clay is first lowered using twenty-four hour heat treatments of no heat, 130 C, 150 C, or 170 C to fixate the lithium ions within the clay layers so that they are unexchangeable. Generally, higher temperatures have generated lower cation exchange capacities. An ion exchange involving dodecylamine, octadecylamine, or dimethyl benzidine (DMBZ) is then employed to actually expand the clay galleries. X-ray diffraction and transmission electron microscopy can be used to determine whether the clay has been successfully exfoliated. Finally, resins of DMBZ with clay are then pressed into disks for characterization using dynamic mechanical analyzer and oven- aging techniques in order to evaluate their glass transition, modulus strength, and thermal-oxidative stability in comparison to neat DMBZ. In the future, they may also be tested as composites for flexural and laminar shear strength.

  2. Xenon-129 NMR study of the microporous structure of clays and pillared clays

    SciTech Connect

    Tsiao, C.; Carrado, K.A.

    1990-01-01

    {sup 129}Xe NMR studies have been carried out using xenon gas adsorbed in clays and pillared clays. Data from the measurements provide information on the pore structure of clays before and after pillaring. The results indicate that the effective pore diameter of montmorillonite increases, for example, from 5.4 {Angstrom} to 8.0 {Angstrom} after pillaring cheto-montmorillonite with aluminum polyoxohydroxy Keggin cations. The data are consistent with X-ray powder diffraction results, which show a corresponding increase in the interlamellar gallery height from 5.6 {Angstrom} to 8.4 {Angstrom}.

  3. Classroom Instruction: The Influences of Marie Clay

    ERIC Educational Resources Information Center

    McNaughton, Stuart

    2014-01-01

    Marie Clay's body of work has influenced classroom instruction in direct and indirect ways, through large overarching themes in our pedagogical content knowledge as well as specific smart practices. This paper focuses on her the contributions to our thinking about instruction which come from two broad theoretical concepts; emergent literacy…

  4. REPORT OF WORKSHOP ON GEOSYNTHETIC CLAY LINERS

    EPA Science Inventory

    The purpose of the report is to summarize the information presented at the Geosynthetic Clay Liner (GCL) workshop held on July 9-10, 1992. The report does not represent the full extent of the information available on geosynthetic liners. Readers are directed to the summary of th...

  5. Black Carbon, The Pyrogenic Clay Mineral?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  6. Diffusion in Clay Layers and Groundwater Remediation

    EPA Science Inventory

    In a collaborative SERDP-funded study, researchers from the Air Force Institute of Technology, the U.S. Environmental Protection Agency, and the University of Michigan developed a numerical model that simulates the enhanced transport of CAHs into and out of low permeability clay ...

  7. Palaeoceanographic approach to the Kimmeridge Clay Formation

    SciTech Connect

    Miller, R.G. )

    1988-08-01

    The Upper Jurassic/Lower Cretaceous Kimmeridge Clay Formation (KCF) is northern Europe's premier source rock and can be understood using a new but relatively simple oceanographic model. This explains or accommodates most current observations about the KCF and its depositional environment and draws upon paleogeographic, paleoclimatic, geochemical, sedimentological, and paleontological evidence.

  8. HYDRAULIC CONDUCTIVITY OF THREE GEOSYNTHETIC CLAY LINERS

    EPA Science Inventory

    The hydraulic conductivity of three 2.9 m2 (32 sq ft) geosynthetic clay liners (GCLs) was measured. Tests were performed on individual sheets of the GCLs, on overlapped pieces of GCLs, and on composite liners consisting of a punctured geomembrane overlying a GCL. Hyd...

  9. Calm, Cool, and Comfortable in Clay

    ERIC Educational Resources Information Center

    Stylianou, Xanthippi Cynthia

    2010-01-01

    The author's fourth-grade students had just finished a drawing unit that focused on the human figure. Projects included charcoal gesture drawings and chalk manikin drawings in chiaroscuro. She wanted to integrate a new medium for students to continue their study of the human figure. Since students are always excited to work with clay, making clay…

  10. Bauxite washing for the removal of clay

    NASA Astrophysics Data System (ADS)

    Ahmad, Ishaq; Hartge, Ernst-Ulrich; Werther, Joachim; Wischnewski, Reiner

    2014-11-01

    Clay impurities associated with bauxite negatively affect the Bayer process for alumina production. These impurities should be removed as far as possible by a beneficiation technique before the ore is used as feed for the Bayer process. In this current investigation, bauxite washing was conducted in the laboratory. Bauxite washing is a physical process that causes the disintegration and deagglomeration of the clay matrix, and bauxite is liberated from the clay (mainly rich in silica). Subsequently, separation occurs with the assistance of wet screening at a predetermined cut size. Three techniques were investigated in the laboratory: drum washing, water-jet washing, and ultrasonic washing. Various operating parameters were investigated for drum washing and water-jet washing, including materials retention time, drum rotation speed, solid concentration, water-jet spray duration, pressure, and height. We concluded that the retention time of bauxite inside the drum at a solid concentration of 55wt% and a drum rotation speed of 31 r/min is the dominant parameter for the removal of clay from the bauxite surface.

  11. Transport of Organic Solutes in Clay Formations

    EPA Science Inventory

    The research is a pilot investigation for the SERDP (Strategic Environmental Research and Development Program, DoD) founded project, Impact of Clay-DNAPL Interactions on Transport and Storage of Chlorinated Solvents in Low Permeability Zones, from 2010-2012. The report tries to s...

  12. Clay Corner: Recreating Chinese Bronze Vessels.

    ERIC Educational Resources Information Center

    Gamble, Harriet

    1998-01-01

    Presents a lesson where students make faux Chinese bronze vessels through slab or coil clay construction after they learn about the history, function, and design of these vessels. Utilizes a variety of glaze finishes in order to give the vessels an aged look. Gives detailed guidelines for creating the vessels. (CMK)

  13. INTERIOR VIEW ON SEVENTH FLOOR AT CORNER OF CLAY AND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    INTERIOR VIEW ON SEVENTH FLOOR AT CORNER OF CLAY AND 15TH STREETS. LARGE SECTIONS OF DEMOLISHED SHEET METAL CORNICE FROM BUILDING EXTERIOR VISIBLE FOREGROUND - John Breuner & Company Building, 1515 Clay Street, Oakland, Alameda County, CA

  14. INTERIOR VIEW ON MEZZANINE ALONG EAST (CLAY STREET) FRONT FACING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    INTERIOR VIEW ON MEZZANINE ALONG EAST (CLAY STREET) FRONT FACING OAKLAND CITY HALL. TYPICAL INTERIOR CONDITIONS OF PARTIAL DEMOLITION; WINDOWS, WINDOW FRAMES, SUSPENDED CEILING, AND MOVABLE PARTITION WALLS REMOVED - John Breuner & Company Building, 1515 Clay Street, Oakland, Alameda County, CA

  15. Deformation mechanisms in experimentally deformed Boom Clay

    NASA Astrophysics Data System (ADS)

    Desbois, Guillaume; Schuck, Bernhard; Urai, Janos

    2016-04-01

    Bulk mechanical and transport properties of reference claystones for deep disposal of radioactive waste have been investigated since many years but little is known about microscale deformation mechanisms because accessing the relevant microstructure in these soft, very fine-grained, low permeable and low porous materials remains difficult. Recent development of ion beam polishing methods to prepare high quality damage free surfaces for scanning electron microscope (SEM) is opening new fields of microstructural investigation in claystones towards a better understanding of the deformation behavior transitional between rocks and soils. We present results of Boom Clay deformed in a triaxial cell in a consolidated - undrained test at a confining pressure of 0.375 MPa (i.e. close to natural value), with σ1 perpendicular to the bedding. Experiments stopped at 20 % strain. As a first approximation, the plasticity of the sample can be described by a Mohr-Coulomb type failure envelope with a coefficient of cohesion C = 0.117 MPa and an internal friction angle ϕ = 18.7°. After deformation test, the bulk sample shows a shear zone at an angle of about 35° from the vertical with an offset of about 5 mm. We used the "Lamipeel" method that allows producing a permanent absolutely plane and large size etched micro relief-replica in order to localize and to document the shear zone at the scale of the deformed core. High-resolution imaging of microstructures was mostly done by using the BIB-SEM method on key-regions identified after the "Lamipeel" method. Detailed BIB-SEM investigations of shear zones show the following: the boundaries between the shear zone and the host rock are sharp, clay aggregates and clastic grains are strongly reoriented parallel to the shear direction, and the porosity is significantly reduced in the shear zone and the grain size is smaller in the shear zone than in the host rock but there is no evidence for broken grains. Comparison of microstructures

  16. Glowing clay: Real time tracing using a suite of novel clay based fluorescent tracers

    NASA Astrophysics Data System (ADS)

    Hardy, Robert; Quinton, John; Pates, Jackie; Coogan, Mike

    2015-04-01

    Clay is one of the most mobile fractions of soil due to its small particle size. It is also known to sorb many chemicals, such as nutrients (notably phosphorus), agrochemicals and heavy metals. The movement of clay is therefore linked with the transport and fate of these substances. A novel fluorescent clay tracing suite has been produced, together with an imaging technique. This suite consists of qualitative clay tracers, using rhodamine based fluorophores, and quantitative clay tracers, using metal based fluorophores. Efforts have also been made to allow integration of commercially available tracers, which are silt and sand sized. The clay tracers exploit the high affinity that montmorillonite has for Rhodamine B and Ru(bpy)3. This allows for an extremely thin layer of the fluorophore to be sorbed onto the clay's surface, in much that same way as materials in the natural environment will bind to clay. The tracer that is produced retains key chemical and physical properties of clay, such as size, shape and density. The retention of these micro-properties results in the retention of macro-properties, such as tendency to aggregate and cracking on drying. Imaging techniques have been developed to analyse these tracers. The imaging system uses diffused laser light to excite the tracer and a modified DSLR camera to image the soil surface. The images have been compiled into a time lapse video showing the movement of clay over the course of a rainfall event. This is the first time that the quantitative movement of clay has been recorded over a soil surface in real time. 4D data can be extracted from the images allowing the spatial location and intensity of tracer to be monitored over time, with mm precision and on the timescale of seconds. As the system can also work with a commercial tracer it is possible to investigate the movement of particles of almost any size and over a range of scales from soil box to hillside. This allows users to access this technique without

  17. Zeta potential measurements on three clays from Turkey and effects of clays on coal flotation

    SciTech Connect

    Hussain, S.A.; Demirici, S.; Oezbayoglu, G.

    1996-12-25

    There is a growing trend of characterizing coal and coal wastes in order to study the effect of clays present in them during coal washing. Coarse wastes from the Zonguldak Coal Washery, Turkey, were characterized and found to contain kaolinite, illite, and chlorite. These three clays, obtained in almost pure form from various locations in Turkey, have been subjected to X-ray diffraction (XRD) analysis to assess their purity and zeta potential measurements in order to evaluate their properties in terms of their surface charge and point of zero charge (pzc) values. It was found from XRD data that these clays were almost pure and their electrokinetic potential should therefore be representative of their colloidal behavior. All three clay minerals were negatively charged over the range from pH 2.5 to 11. Chlorite and illite have pzc at pH 3 and pH 2.5, respectively, whereas kaolinite has no pzc. The effect of these clays in Zonguldak coal, wastes, and black waters on coal flotation was studied by floating artificial mixtures of Zonguldak clean coal (4.5% ash) and individual clay. The flotation tests on coal/individual clay revealed that each clay influences coal flotation differently according to its type and amount. Illite had the worst effect on coal floated, followed by chlorite and kaolinite. The loss of yield in coal was found to be 18% for kaolinite, 20% for chlorite, and 28% for illite, indicating the worst effect of illite and least for kaolinite during coal flotation.

  18. Zeta Potential Measurements on Three Clays from Turkey and Effects of Clays on Coal Flotation

    PubMed

    Hussain; Dem&idot;rc&idot;; özbayoğlu

    1996-12-25

    There is a growing trend of characterizing coal and coal wastes in order to study the effect of clays present in them during coal washing. Coarse wastes from the Zonguldak Coal Washery, Turkey, were characterized and found to contain kaolinite, illite, and chlorite. These three clays, obtained in almost pure form from various locations in Turkey, have been subjected to X-ray diffraction (XRD) analysis to assess their purity and zeta potential measurements in order to evaluate their properties in terms of their surface charge and point of zero charge (pzc) values. It was found from XRD data that these clays were almost pure and their electrokinetic potential should therefore be representative of their colloidal behavior. All three clay minerals were negatively charged over the range from pH 2.5 to 11. Chlorite and illite have pzc at pH 3 and pH 2.5, respectively, whereas kaolinite has no pzc. The effect of these clays in Zonguldak coal, wastes, and black waters on coal flotation was studied by floating artificial mixtures of Zonguldak clean coal (4.5% ash) and individual clay. The flotation tests on coal/individual clay revealed that each clay influences coal flotation differently according to its type and amount. Illite had the worst effect on coal floated, followed by chlorite and kaolinite. The loss of yield in coal was found to be 18% for kaolinite, 20% for chlorite, and 28% for illite, indicating the worst effect of illite and least for kaolinite during coal flotation. PMID:8978557

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

    NASA Astrophysics Data System (ADS)

    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..

  20. FACING NORTH ALONG CLAY STREET, SHOWING BUILDINGS ON THE WEST ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    FACING NORTH ALONG CLAY STREET, SHOWING BUILDINGS ON THE WEST SIDE OF CLAY STREET, FROM LEFT TO RIGHT: JOHN BREUNER AND COMPANY BUILDING (FOREGROUND), HOTEL TOURAINE (MIDDLE), AND THE PACIFIC GAS AND ELECTRIC CO. BUILDING - John Breuner & Company Building, 1515 Clay Street, Oakland, Alameda County, CA

  1. Clay Menagerie: An Interview with Patricia Uchill Simons.

    ERIC Educational Resources Information Center

    Gamble, Harriet

    2001-01-01

    Presents an interview with artist Patricia Uchill Simons, focusing on her history as a clay artist, why she uses clay, when she started making her menagerie of animals, her process for creating her artwork, her teaching experience, and why she believes clay is a good medium for students. (CMK)

  2. Enrichment and activation of smectite-poor clay

    NASA Astrophysics Data System (ADS)

    Sarceviča, Inese; Kostjukovs, Juris; Actiņš, Andris

    2011-06-01

    A new method of smectite clay enrichment has been developed. The method is based on dispersing clay in a phosphate solution and sequential coagulation. The product of enrichment is characterized with X-ray powder diffraction, wavelength dispersive X-ray fluorescence spectrometry, differential thermal analysis and thermogravimetry. Sorption of methylene blue and hexadecylpyridinium bromide on raw and purified clays was studied.

  3. Clays causing adhesion with tool surfaces during mechanical tunnel driving

    NASA Astrophysics Data System (ADS)

    Spagnoli, G.; Fernández-Steeger, T.; Stanjek, H.; Feinendegen, M.; Post, C.; Azzam, R.

    2009-04-01

    During mechanical excavation with a tunnel boring machine (TBM) it is possible that clays stick to the cutting wheel and to other metal parts. The resulting delays in the progress of construction work, cause great economic damage and often disputes between the public awarding authorities and executing companies. One of the most important factors to reduce successfully the clay adhesion is the use of special polymers and foams. But why does the clay stick to the metal parts? A first step is to recognize which kind of clay mineralogy shows serious adhesion problems. The mechanical properties of clay and clay suspensions are primarily determined by surface chemistry and charge distribution at the interfaces, which in turn affect the arrangement of the clay structure. As we know, clay is a multi-phase material and its behaviour depends on numerous parameters such as: clay mineralogy, clay fraction, silt fraction, sand fraction, water content, water saturation, Atterberg limits, sticky limit, activity, cation exchange capacity, degree of consolidation and stress state. It is therefore likely that adhesion of clay on steel is also affected by these clay parameters. Samples of clay formations, which caused problems during tunnel driving, will be analyzed in laboratory. Mineralogical analyses (diffractometry, etc.) will be carried out to observe which minerals are responsible for adherence problems. To manipulate the physical properties, batch tests will be carried out in order to eliminate or reduce the adhesion on tool surfaces through variation of the zeta potential. Second step is the performance of vane shear tests on clay samples. Different pore fluid (distilled water, pure NaCl solution, ethanol and methanol) will be used to study the variation of the mechanical behaviour of clay depending on the dielectric constant of the fluids. This project is funded by the German Federal Ministry of Education and Research (BMBF) and the DFG (German Research Foundation) in the

  4. Coatings and films derived from clay/wax nanocomposites

    DOEpatents

    Chaiko, David J.; Leyva, Argentina A.

    2006-11-14

    The invention provides methods for making clay/wax nanocomposites and coatings and films of same with improved chemical resistance and gas barrier properties. The invention further provides methods for making and using emulsions of such clay/wax nanocomposites. Typically, an organophillic clay is combined with a wax or wax/polymer blend such that the cohesion energy of the clay matches that of the wax or wax/polymer blend. Suitable organophilic clays include mica and phyllosilicates that have been surface-treated with edge or edge and surface modifying agents. The resulting nanocomposites have applications as industrial coatings and in protective packaging.

  5. Chemical disaggregation of kaolinitic claystones (tonsteins and flint clays)

    USGS Publications Warehouse

    Triplehorn, D.M.; Bohor, B.F.; Betterton, W.J.

    2002-01-01

    The coarse, non-clay fraction of many flint-like kaolinitic claystones often contains mineral grains diagnostic of the claystone's origin and, in the case of tonsteins (altered volcanic ashes), may also provide minerals suitable for radiometric dating. Separation of the non-clay mineral fraction is often difficult because flint clays and flint-like clays resist slaking in water and thus are difficult to disaggregate. Chemical disaggregation of resistant kaolinitic claystones may be achieved by immersion in either hydrazine monohydrate or DMSO for periods ranging from one day to several weeks. Generally, hydrazine monohydrate works more quickly and efficiently than DMSO to disaggregate most kaolinitic claystones and flint clays.

  6. Geotechnical characterization of mined clay from Appalachian Ohio: challenges and implications for the clay mining industry.

    PubMed

    Moran, Anthony R; Hettiarachchi, Hiroshan

    2011-07-01

    Clayey soil found in coal mines in Appalachian Ohio is often sold to landfills for constructing Recompacted Soil Liners (RSL) in landfills. Since clayey soils possess low hydraulic conductivity, the suitability of mined clay for RSL in Ohio is first assessed by determining its clay content. When soil samples are tested in a laboratory, the same engineering properties are typically expected for the soils originated from the same source, provided that the testing techniques applied are standard, but mined clay from Appalachian Ohio has shown drastic differences in particle size distribution depending on the sampling and/or laboratory processing methods. Sometimes more than a 10 percent decrease in the clay content is observed in the samples collected at the stockpiles, compared to those collected through reverse circulation drilling. This discrepancy poses a challenge to geotechnical engineers who work on the prequalification process of RSL material as it can result in misleading estimates of the hydraulic conductivity of the samples. This paper describes a laboratory investigation conducted on mined clay from Appalachian Ohio to determine how and why the standard sampling and/or processing methods can affect the grain-size distributions. The variation in the clay content was determined to be due to heavy concentrations of shale fragments in the clayey soils. It was also concluded that, in order to obtain reliable grain size distributions from the samples collected at a stockpile of mined clay, the material needs to be processed using a soil grinder. Otherwise, the samples should be collected through drilling. PMID:21845150

  7. Nonspecific Compatibilization of Polymer Blends Using Functionalized Clays

    NASA Astrophysics Data System (ADS)

    Fisher, Robert; Goldman, Michael; Rubinstein, Michael; Si, Mayu; Sokolov, Jonathan; Rafailovich, Miriam; Ruderman, Gregory

    2003-03-01

    Binary and tertiary blends of polystyrene (PS), polymethylmethacrylate (PMMA) , and poletheylene terephthalate (PET) were produced by melt mixing in a Brabender twin screw extruder at 100RPM, 180C . Ten weight percent Cloisite 20A clay (Southern Clay Corp) was then added to some of the mixtures after ten minutes. In one case the clay was fist melt mixed with all three polymer components separately and then the three polymer/clay composites were melt mixed together. The samples were examined with transmission electron microscopy which revealed that the addition of clay during melt mixing produced a material that was much more homogenous than the material without clay or where the clay was first mixed individually into the components. This was confirmed by DMA analysis where the melt mixed sample with clay exhibited only one glass transition for both binary and tertiary blends, whereas the sample without clay, or where clay was first mixed into the individual components showed two glass transitions. These results were interpreted in terms of an in situ grafting model where the large surface to volume ration of the clay platelets was able to drastically reduce interfacial tension and hence domain size in the blends.

  8. Dioxins in primary kaolin and secondary kaolinitic clays.

    PubMed

    Schmitz, Martin; Scheeder, Georg; Bernau, Sarah; Dohrmann, Reiner; Germann, Klaus

    2011-01-15

    Since 1996 dioxins have been repeatedly detected worldwide in Tertiary ball clays used as anticaking agent in the production of animal feed and a variety of other applications. The dioxins of these natural clays are very unlikely of anthropogenic source, but no model of dioxin enrichment has been established. A hypothetical model is presented which explains the highly variable dioxin loadings of the Tertiary kaolinitic clays by natural addition during clay-sedimentation. To prove this hypothesis, Tertiary primary nonsedimentary kaolin and sedimentary kaolinitic clays were collected at three profiles in Europe and analyzed for mineralogy, chemistry, organic carbon, and polychlorinated dibenzo-p-dioxins/-furans (PCDD/F). Primary kaolin, kaolinitic, and lignitic clays contained almost no PCDFs. PCDD concentration differed markedly between primary kaolin (3-91 pg/g) and secondary kaolinitic clay (711-45935 pg/g), respectively, lignitic clays (13513-1191120 pg/g). The dioxin loading of secondary kaolinitic and lignitic clays is approximately 10 to a few thousand times higher than in the primary kaolin or recent environmental settings. The dioxin concentrations decrease from octachlorodibenzo-p-dioxin to the tetrachlorodibenzo-p-dioxins and exhibit the "natural formation pattern". No correlation between PCDD/F concentration and bulk composition of clays was found. These findings support the hypothesis of the enrichment of dioxin in clays during sedimentation. PMID:21126071

  9. Characterization and adsorptive properties of pharmaceutical grade clays.

    PubMed

    Browne, J E; Feldkamp, J R; White, J L; Hem, S L

    1980-07-01

    The adsorption of tetracycline by clays commonly used in pharmacy can be predicted if the identity and character of the commerical clay sample are established. X-ray diffraction. IR spectroscopy, and chemical analysis were used to identify the clay component and any nonclay diluents present in a series of commerical pharmaceutical grade clays. The major clay components were montmorillonite, hectorite, attapulgite, saponite, and kaolinite. The clay structure, the nature of the exchangeable cation, and the presence of nonclay components are important factors affecting the tetracycline-clay interaction. In general, clay structures with a high surface charge lead to a greater interaction with the protonated form of tetracycline, while interaction with the zwitterionic form of tetracycline occurs in clay structures with minimal surface charge. The presence of multivalent, exchangeable cations on the clay surface diminishes interaction with the protonated form of tetracycline. Nonclay components such as calcite and dolomite increase the interactions of the zwitterionic and anionic forms of tetracycline with the clay. PMID:7391947

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

    PubMed

    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. PMID:24035982

  11. Clay mineral formation and transformation in rocks and soils

    USGS Publications Warehouse

    Eberl, D.D.

    1983-01-01

    Three mechanisms for clay mineral formation (inheritance, neoformation, and transformation) operating in three geological environments (weathering, sedimentary, and diagenetic-hydrothermal) yield nine possibilities for the origin of clay minerals in nature. Several of these possibilities are discussed in terms of the rock cycle. The mineralogy of clays neoformed in the weathering environment is a function of solution chemistry, with the most dilute solutions favoring formation of the least soluble clays. After erosion and transportation, these clays may be deposited on the ocean floor in a lateral sequence that depends on floccule size. Clays undergo little reaction in the ocean, except for ion exchange and the neoformation of smectite; therefore, most clays found on the ocean floor are inherited from adjacent continents. Upon burial and heating, however, dioctahedral smectite reacts in the diagenetic environment to yield mixed-layer illite-smectite, and finally illite. With uplift and weathering, the cycle begins again. Refs.

  12. Sonochemical intercalation of preformed gold nanoparticles into multilayered clays.

    PubMed

    Belova, Valentina; Möhwald, Helmuth; Shchukin, Dmitry G

    2008-09-01

    Multilayered Na (+)-montmorillonite clays intercalated with Au nanoparticles were synthesized by direct ultrasonic impregnation of preformed gold colloid into the clay matrix. The sonicated composite product then consists of Au nanoparticles homogeneously dispersed in the clay. The resulting clay/nano-Au composite was calcined at 800 degrees C and characterized by BET surface area analysis, transmission electron microscopy, scanning electron microscopy, X-ray diffraction, and Fourier transform infrared measurements. Nearly spherical-shaped gold nanoparticles, with a size of 6 +/- 0.5 nm, are located in the pores of clay calcined at 800 degrees C. Their nanocomposites are thermally stable as was shown by thermogravimetric analysis. No aggregation of the gold nanoparticles was observed during calcination. The proposed ultrasonic intercalation approach is an universal one and can be employed for synthesis of catalytically active metal-clay nanocomposites stable at high temperatures with high dispersability of the metal nanoparticles in the clay matrix. PMID:18652497

  13. CLAY MINERALOGY OF INSOLUBLE RESIDUES IN MARINE EVAPORITES.

    USGS Publications Warehouse

    Bodine, Marc W., Jr.

    1985-01-01

    Insoluble residues from three sequences of Paleozoic marine evaporites (Retsof salt bed in western New York, Salado Formation in south-eastern New Mexico, and Paradox Member of the Hermosa Formation in southeastern Utah) are rich in trioctahedral clays. Chlorite (clinochlore), corrensite (mixed-layer chlorite-trioctahedral smectite), talc, and illite (the only dioctahedral clay) are the dominant clay minerals; serpentine, discrete trioctahedral smectite (saponite), and interstratified talc-trioctahedral smectite are sporadically abundant. These clay-mineral assemblages differ chemically and mineralogically from those observed in most continental and normal marine rocks, which commonly contain kaolinite, dioctahedral smectite (beidellite-montmorillonite), illite, mixed-layer illite-dioctahedral smectite, and, in most cases, no more than minor quantities of trioctahedral clay minerals. The distinctive clay mineralogy in these evaporite sequences suggests a largely authigenic origin. These clay minerals are thought to have formed during deposition and early diagenesis through interaction between argillaceous detritus and Mg-rich marine evaporite brines.

  14. Feasibility of classification of clay minerals by using PAS

    NASA Astrophysics Data System (ADS)

    Honda, Y.; Yoshida, Y.; Akiyama, Y.; Nishijima, S.

    2015-06-01

    After the nuclear power plant disaster, the evaluation of radioactive Cs kept in soil, especially in clay minerals and the elucidation of its movement are urgent subjects to promote decontamination. It is known that the extractable level of Cs depends on the sort of clay minerals. We tried to find the characteristics of clay minerals belonging to phillosilicate group using positron annihilation spectroscopy (PAS) and the relationship between the results of PAS and the amounts of substantially extracted Cs from the clay minerals. The results showed that each clay mineral was found to be distinguishable from other clay minerals by PAS and the extraction rate of Cs was different among those clay minerals, however the direct correlation between the results of PAS and the extraction rates of Cs was not found.

  15. Selecting brines and clay stabilizers to prevent formation damage

    SciTech Connect

    Evans, B.; Ali, S.

    1997-05-01

    Although many technical reports have been written about formation damage caused by brine/formation interactions, this article discusses the effects brines and chemical clay stabilizers have on pure samples of kaolinite, smectite, illite and chlorite clays. Analytical chemistry and geochemical models were not employed in this study; instead, capillary suction time tests were used to empirically compare clay migration and swelling characteristics when samples were exposed to certain brine/clay stabilizer combinations. Objective of the study was to determine which type of clay was most damaging in reservoir rocks, and whether one brine or chemical stabilizer could meet the needs of stabilizing all clay types. This information is provided with well completion operations in mind, especially when fluid cost/performance is a major concern. This article compares the unique brine/chemical stabilizer reaction characteristics of each clay type common to oil and gas reservoirs.

  16. Silt-clay aggregates on Mars

    NASA Technical Reports Server (NTRS)

    Greeley, R.

    1979-01-01

    Viking observations suggest abundant silt and clay particles on Mars. It is proposed that some of these particles agglomerate to form sand size aggregates that are redeposited as sandlike features such as drifts and dunes. Although the binding for the aggregates could include salt cementation or other mechanisms, electrostatic bonding is considered to be a primary force holding the aggregates together. Various laboratory experiments conducted since the 19th century, and as reported here for simulated Martian conditions, show that both the magnitude and sign of electrical charges on windblown particles are functions of particle velocity, shape and composition, atmospheric pressure, atmospheric composition and other factors. Electrical charges have been measured for saltating particles in the wind tunnel and in the field, on the surfaces of sand dunes, and within dust clouds on earth. Similar, and perhaps even greater, charges are proposed to occur on Mars, which could form aggregates of silt and clay size particles

  17. Freezing D2O clay gels.

    PubMed

    Letellier, M

    1998-01-01

    To obtain the T1 surface value in smectites/D2O diluted suspensions or gels, as was obtained on a monolayer deuterated clay, we freeze them. The broad Pake's doublets similar to ice doublets and with the same T1 show that we can separate frozen from unfrozen D2O. The latter exhibits a narrower line and a single T1 and is attributed to the liquid surface water layer in rapid exchange with the nearby supercooled water, the quantity of which diminishes with the lowering of the temperature depending on the gel porosity. It is possible to measure the supercooled water quantity and to correct the T1 measured values to extract the T1 surface. The value extrapolated at room temperature allows the complete clay surface area measurement. The example of a montmorillonite is given and a comparison with laponite is made. PMID:9803898

  18. Clay-based geothermal drilling fluids

    SciTech Connect

    Guven, N.; Carney, L.L.; Lee, L.J.; Bernhard, R.P.

    1982-11-01

    The rheological properties of fluids based on fibrous clays such as sepiolite and attapulgite have been systematically examined under conditions similar to those of geothermal wells, i.e. at elevated temperatures and pressures in environments with concentrated brines. Attapulgite- and sepiolite-based fluids have been autoclaved at temperatures in the range from 70 to 800/sup 0/F with the addition of chlorides and hydroxides of Na, K, Ca, and Mg. The rheological properties (apparent and plastic viscosity, fluid loss, gel strength, yield point, and cake thickness) of the autoclaved fluids have been studied and correlated with the chemical and physical changes that occur in the clay minerals during the autoclaving process.

  19. Organically modified clay removes oil from water

    SciTech Connect

    Alther, G.R.

    1995-12-31

    When bentonite or other clays and zeolites are modified with quaternary amines, they become organophilic. Such modified bentonites are used to remove mechanically emulsified oil and grease, and other sparingly soluble organics. If the organoclay is granulated, it is placed into a liquid phase carbon filter vessel to remove FOG`s and chlorinated hydrocarbons. In this application the clay is mixed with anthrazite to prevent early plugging of the filter by oil or grease droplets. In batch systems a powered organoclay is employed. Types of oil found in water can include fats, lubricants, cutting fluids, heavy hydrocarbons such as tars, grease, crude oil, diesel oils; and light hydrocarbons such as kerosene, jet fuel, and gasoline.

  20. Humidity Dependent Extinction of Clay Aerosols

    NASA Astrophysics Data System (ADS)

    Greenslade, M. E.; Attwood, A. R.

    2010-12-01

    Aerosols play an important role in the Earth’s radiative balance by directly scattering and absorbing radiation. The magnitude of aerosol forcing can be altered by changes in relative humidity which cause aerosol size, shape and refractive index to vary. To quantify these effects, a custom cavity ring down instrument operated at 532 nm with two sample channels measures aerosols extinction under dry conditions and at elevated humidity. The optical growth, fRH(ext), is determined as a ratio of the extinction cross section at high relative humidity to that under dry conditions. Three key clay components of mineral dust and mixtures of clay components with ammonium sulfate are investigated using this method. Experimentally obtained optical growth is compared with physical growth factors from the literature and our work determined using several different techniques. Further, Mie theory calculations based on published optical constants are compared with experimental results. Differences between theory and experiment will be discussed.

  1. Application of modulus degradation model of clays.

    USGS Publications Warehouse

    Chen, A.T.F.

    1982-01-01

    A degradation model is applied in conjunction with different soil models and stress-strain relations to site response analyses during earthquakes. To evaluate the effects of degradation, computations on two clay deposits subjected to both high and low-level input excitations are conducted. Where surface response differs, the use of degradation with strength reduction is less conservative when compared to the use of degradation without strength reduction.- from ASCE Publications Abstracts

  2. Electrically induced reduction of trichloroethene in clay.

    PubMed

    Jin, Song; Fallgren, Paul H

    2010-01-15

    Chlorinated compounds such as trichloroethene (TCE) are recalcitrant contaminants commonly detected in soil and groundwater. Contemporary remedies such as electron donor amendment tend to be less or ineffective in treating chlorinated compounds in matrix of lower permeability, such as clay. In this study, electrically induced reduction (EIR) was tested by inserting electrodes in saturated clay containing 122.49-125.43 mg TCE kg(-1). Weak electric potentials (E) of 6, 9, and 12 V m(-1) were applied, and up to 97% of TCE were depleted during the study period. Corresponding increases in chloride concentrations was observed during TCE depletion, indicating a reductive dechlorination pathway. No migration of TCE was observed between the two electrodes, neither were intermediate compounds such as dichloroethene (DCE) or vinyl chloride (VC). Results were also tested against a mathematical equation we previously established for field applications. Electrically induced reduction may offer a novel method for in situ degradation of chlorinated contaminants, especially in low-permeable media such as clay. PMID:19729244

  3. Electrokinetics of pure clay minerals revisited

    SciTech Connect

    Sondi, I.; Biscan, J.; Pravdic, V.

    1996-03-25

    Clay minerals have long attracted the attention of colloid scientists. This paper considers, specifically, their important role in the transport of various contaminants from land to sea, e.g., metal ions and organic detrital and man-made material in watercourses. Advance in experimental techniques have enabled precise characterization of clays and then electrokinetic experiments at high electrolyte concentrations, such as in seawater. Three of the most important clay minerals encountered in suspended matter in natural waters, montmorillonite, illite, and chlorite, were prepared in a very pure state. Electrokinetic experiments were done in pure aqueous single and complex electrolyte solutions and in solutions in which natural organic matter was simulated using a humic substance, fulvic acid, of defined provenance and properties, typical of riverine waters. An isoelectric point was found at pH 5.0 {+-} 0.2 for chlorite; none were found for illite and montmorillonite. Only Ca{sup 2+} showed a charging effect on chlorite, indeed a reversal of sign from negative to positive at 1 {times} 10{sup {minus}3} mol dm{sup {minus}3}. Addition of fulvic acid affected only chlorite, illite less, and Na montmorillonite not at all.

  4. Role of bentonite clays on cell growth.

    PubMed

    Cervini-Silva, Javiera; Ramírez-Apan, María Teresa; Kaufhold, Stephan; Ufer, Kristian; Palacios, Eduardo; Montoya, Ascención

    2016-04-01

    Bentonites, naturally occurring clays, are produced industrially because of their adsorbent capacity but little is known about their effects on human health. This manuscript reports on the effect of bentonites on cell growth behaviour. Bentonites collected from India (Bent-India), Hungary (Bent-Hungary), Argentina (Bent-Argentina), and Indonesia (Bent-Indonesia) were studied. All four bentonites were screened in-vitro against two human cancer cell lines [U251 (central nervous system, glioblastoma) and SKLU-1 (lung adenocarcinoma)] supplied by the National Cancer Institute (USA). Bentonites induced growth inhibition in the presence of U251 cells, and growth increment in the presence of SKLU-1 cells, showing that interactions between bentonite and cell surfaces were highly specific. The proliferation response for U251 cells was explained because clay surfaces controlled the levels of metabolic growth components, thereby inhibiting the development of high-grade gliomas, particularly primary glioblastomas. On the other hand, the proliferation response for SKLU-1 was explained by an exacerbated growth favoured by swelling, and concomitant accumulation of solutes, and their hydration and transformation via clay-surface mediated reactions. PMID:26849195

  5. Spectromicroscopy of Fe distributions in clay microcrystals

    SciTech Connect

    Grundl, T.; Cerasari, S.; Garcia, A.

    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.

  6. Anaerobic degradation of DCM diffusing through clay

    SciTech Connect

    Rowe, R.K.; Hrapovic, L.; Kosaric, N.; Cullimore, D.R.

    1997-12-01

    Two series of diffusion tests were performed to examine the degradation of dichloromethane (DCM) as it diffuses through clay. The first series showed the use of a synthetic leachate with no significant initial bacterial population diffusing through a plug of intact clay; there was an induction period of 95--135 d, during which diffusion was as expected in the absence of degradation, followed by a second stage, where degradation occurred with an apparent half-life of less than 55 d at a temperature of 24 C. The second series of tests examined the diffusion of an actual leachate from the Keele Valley Landfill (KVL) (which provided both nutrients and a source of bacteria), through a compacted clay. In these tests, the induction period was reduced to 40--60 d, after which the apparent half-life was 20 d or less at 27 C. The diffusion coefficient for DCM was approximately 8 {times} 10{sup {minus}10} m{sup 2}/s, with partitioning coefficient K{sub d} = 1.5 cm{sup 3}/g. Biological activity was confirmed by evaluating the change in the concentration of adenosine-5-triphosphate and the biological activity reaction test (BART). The degradation of DCM did not produce any detectable levels of chloromethane.

  7. Molecular interactions alter clay and polymer structure in polymer clay nanocomposites.

    PubMed

    Sikdar, Debashis; Katti, Kalpana S; Katti, Dinesh R

    2008-04-01

    In this work, using photoacoustic Fourier transform infrared spectroscopy (FTIR) we have studied the structural distortion of clay crystal structure in organically modified montmorillonite (OMMT) and polymer clay nanocomposites (PCN). To study the effect of organic modifiers on the distortion of crystal structure of clay, we have synthesized OMMTs and PCNs containing same polymer and clay but with three different organic modifiers (12-aminolauric acid, n-dodecylamine, and 1,12-diaminododecane), and conducted the FTIR study on these PCNs. Our previous molecular dynamics (MD) study on these PCNs reveals that significant nonbonded interactions (van der Waals, electrostatic interactions) exist between the different constituents (polymer, organic modifier, and clay) of nanocomposites. Previous work based on X-ray diffraction (XRD) and differential scanning calorimetry (DSC) on the same set of PCNs shows that crystallinity of polymer in PCNs have changed significantly in comparison to those in pristine polymer; and, the nonbonded interactions between different constituents of PCN are responsible for the change in crystal structure of polymer in PCN. In this work to evaluate the structural distortion of crystal structure of clay in OMMTs and PCNs, the positions of bands corresponding to different modes of vibration of Si-O bonds are determined from the deconvolution of broad Si-O bands in OMMTs and PCNs obtained from FTIR spectra. Intensity and area under the Si-O bands are indicative of orientation of clay crystal structures in OMMTs and PCNs. Significant changes in the Si-O bands are observed from each vibration mode in OMMTs and PCNs containing three different organic modifiers indicating that organic modifiers influence the structural orientation of silica tetrahedra in OMMTs and PCNs. Deconvolution of Si-O bands in OMMTs indicate a band at approximately 1200 cm(-1) that is orientation-dependent Si-O band. The specific changes in intensity and area under this band for

  8. Iodide Sorption to Clays and the Relationship to Surface Charge and Clay Texture - 12356

    SciTech Connect

    Miller, Andrew; Kruichiak, Jessica; Tellez, Hernesto; Wang, Yifeng

    2012-07-01

    Iodine is assumed to behave conservatively in clay barriers around nuclear waste repositories and in natural sediments. Batch experiments tend to show little to no sorption, while in column experiments iodine is often retarded relative to tritiated water. Current surface complexation theory cannot account for negatively charged ion sorption to a negatively charged clay particle. Surface protonation and iodide sorption to clay minerals were examined using surface titrations and batch sorption experiments with a suite of clay minerals. Surface titrations were completed spanning a range of both pH values and ionic strengths. For reference, similar titrations were performed on pure forms of an Al-O powder. The titration curves were deconvoluted to attain the pKa distribution for each material at each ionic strength. The pKa distribution for the Al-O shows two distinct peaks at 4.8 and 7.5, which are invariant with ionic strength. The pKa distribution of clays was highly variable between the different minerals and as a function of ionic strength. Iodide sorption experiments were completed at high solid:solution ratios to exacerbate sorption properties. Palygorskite and kaolinite had the highest amount of iodide sorption and montmorillonite had the least. (authors)

  9. Mechanical dispersion of clay from soil into water: readily-dispersed and spontaneously-dispersed clay

    NASA Astrophysics Data System (ADS)

    Czyż, Ewa A.; Dexter, Anthony R.

    2015-01-01

    A method for the experimental determination of the amount of clay dispersed from soil into water is described. The method was evaluated using soil samples from agricultural fields in 18 locations in Poland. Soil particle size distributions, contents of organic matter and exchangeable cations were measured by standard methods. Sub-samples were placed in distilled water and were subjected to four different energy inputs obtained by different numbers of inversions (end-over-end movements). The amounts of clay that dispersed into suspension were measured by light scattering (turbidimetry). An empirical equation was developed that provided an approximate fit to the experimental data for turbidity as a function of number of inversions. It is suggested that extrapolation of the fitted equation to zero inversions enables the amount of spontaneously-dispersed clay to be estimated. This method introduces the possibility of replacing the existing subjective, qualitative method of determining spontaneously-dispersed clay with a quantitative, objective method. Even though the dispersed clay is measured under saturated conditions, soil samples retain a `memory' of the water contents at which they have been stored.

  10. The direct synthesis of organic-containing clays and thermal analysis of porphyrin-clay complexes

    SciTech Connect

    Carrado, K.A.; Anderson, K.B.; Grutkoski, P.S.

    1991-01-01

    Synthetic TMA-montmorillonites have now been made in conjunction with synthetic porphyrin-hectorites reported earlier. In order to help progress towards preparation of porphyrin-containing aluminosilicate clays, the thermal stability of porphyrin-clay systems has been examined in detail. Results from TGA and Py-GC-MS indicate that the porphyrin nucleus is extremely stable in the present of clay minerals. Substituents on the nucleus such as pyridinium or anilinium are, on the other hand, slightly destabilized. In addition, the presence of transition metals like Fe(III) in metalloporphyrins appears to catalyze decomposition of the porphyrin nucleus to some degree. The use of Py-GC-MS in conjunction with TGA results greatly clarified the assignment of weight loss peaks. 18 refs., 3 figs.

  11. Effects of shock metamorphism on clay mineralogy: Implications for remote sensing of martian clays

    NASA Astrophysics Data System (ADS)

    Michalski, J. R.; Glotch, T. D.; Friedlander, L.; Bish, D. L.; Sharp, T. G.; Dyar, M. D.

    2012-12-01

    One of the most important discoveries in recent exploration of Mars has been the detection of clay minerals within materials exhumed by meteor impact, which point to ancient subsurface alteration and possible habitable conditions at depth. These "crustal clays" occur within central peaks, ejecta, and uplifted rims of many large craters (Ehlmann et al., Nature 2011). The geologic context of phyllosilicates in these settings suggests that most of these deposits represent clays that formed in the subsurface and were later exhumed by impact, rather than clays that formed as a consequence of impact. Therefore, crustal clays exposed at the surface are likely to have experienced some effects of shock metamorphism and/or thermal alteration related to meteor impact. We are investigating the effects of shock metamorphism on the mineralogy of phyllosilicates in the laboratory. Purified, size-separated clay mineral samples were pressed into pellets to decrease internal porosity and were subsequently shocked using the Flat Plate Accelerator at NASA Johnson Space Center. Five minerals (nontronite, saponite, serpentine, chlorite, and kaolinite) were shocked to six pressure steps (10, 20, 25, 30, 35, and 40 GPa). The recovered, shocked samples are being analyzed by thermal infrared emission, visible/near-infrared reflectance, X-ray diffraction (XRD), Mossbauer spectroscopy, and transmission electron microscopy (TEM). Results thus far suggest that shock metamorphism has little effect on the structure or infrared signature of the clay minerals at pressures <20 GPa. One exception is the decrease in 3-D ordering in chlorite at 10 GPa, which steadily decreases until it is essentially lost at 30 GPa. At shock pressures of 20 GPa and higher, all minerals show evidence for broadening of the basal 001 reflection, indicative of progressive decrease in crystallite size. Above 30 GPa, the structures are intensely altered and by 40 GPa, most structural order is lost, based on both XRD and TEM

  12. Geosynthetic clay liners shrinkage under simulated daily thermal cycles.

    PubMed

    Sarabadani, Hamid; Rayhani, Mohammad T

    2014-04-01

    Geosynthetic clay liners are used as part of composite liner systems in municipal solid waste landfills and other applications to restrict the escape of contaminants into the surrounding environment. This is attainable provided that the geosynthetic clay liner panels continuously cover the subsoil. Previous case histories, however, have shown that some geosynthetic clay liner panels are prone to significant shrinkage and separation when an overlying geomembrane is exposed to solar radiation. Experimental models were initiated to evaluate the potential shrinkage of different geosynthetic clay liner products placed over sand and clay subsoils, subjected to simulated daily thermal cycles (60°C for 8 hours and 22°C for 16 hours) modelling field conditions in which the liner is exposed to solar radiation. The variation of geosynthetic clay liner shrinkage was evaluated at specified times by a photogrammetry technique. The manufacturing techniques, the initial moisture content, and the aspect ratio (ratio of length to width) of the geosynthetic clay liner were found to considerably affect the shrinkage of geosynthetic clay liners. The particle size distribution of the subsoil and the associated suction at the geosynthetic clay liner-subsoil interface was also found to have significant effects on the shrinkage of the geosynthetic clay liner. PMID:24718363

  13. Effective Removal of Heavy Metals from Wastewater Using Modified Clay.

    PubMed

    Song, Mun-Seon; Vijayarangamuthu, K; Han, EunJi; Jeon, Ki-Joon

    2016-05-01

    We report an economical and eco-friendly way to remove the heavy metal pollutant using modified clay. The modification of clay was done by calcining the natural clay from Kyushu region in Japan. Further, the removal efficiency for various pH and contact time was evaluated. The morphology of the clays was studied using the scanning electron microscopy (SEM). The structural and chemical analyses of modified clay were done by using X-ray diffraction (XRD), Raman spectroscopy, and Energy dispersion analysis (EDAX) to understand the properties related to the removal of heavy metal pollutant. Further, we studied the absorption efficiency of clay for various pH and contacting time using Ni polluted water. The modified clays show better removal efficiency for all pH with different saturation time. The adsorption follows pseudo-second order kinetics and the adsorption capacity of modified clay is 1.5 times larger than that of natural clay. The increase in the adsorption efficiency of modified clay was correlated to the increase in hematite phase along with increase in surface area due to surface morphological changes. PMID:27483775

  14. Adsorption of dyes using different types of clay: a review

    NASA Astrophysics Data System (ADS)

    Adeyemo, Aderonke Ajibola; Adeoye, Idowu Olatunbosun; Bello, Olugbenga Solomon

    2015-09-01

    Increasing amount of dyes in the ecosystem particularly in wastewater has propelled the search for more efficient low-cost adsorbents. The effective use of the sorption properties (high surface area and surface chemistry, lack of toxicity and potential for ion exchange) of different clays as adsorbents for the removal of different type of dyes (basic, acidic, reactive) from water and wastewater as potential alternatives to activated carbons has recently received widespread attention because of the environmental-friendly nature of clay materials. Insights into the efficiencies of raw and modified/activated clay adsorbents and ways of improving their efficiencies to obtain better results are discussed. Acid-modified clay resulted in higher rate of dye adsorption and an increased surface area and porosity (49.05 mm2 and 53.4 %). Base-modified clay has lower adsorption capacities, while ZnCl2-modified clay had the least rate of adsorption with a surface area of 44.3 mm2 and porosity of 43.4 %. This review also explores the grey areas of the adsorption properties of the raw clays and the improved performance of activated/modified clay materials with particular reference to the effects of pH, temperature, initial dye concentration and adsorbent dosage on the adsorption capacities of the clays. Various challenges encountered in using clay materials are highlighted and a number of future prospects for the adsorbents are proposed.

  15. Clay-catalyzed reactions of coagulant polymers during water chlorination

    USGS Publications Warehouse

    Lee, J.-F.; Liao, P.-M.; Lee, C.-K.; Chao, H.-P.; Peng, C.-L.; Chiou, C.T.

    2004-01-01

    The influence of suspended clay/solid particles on organic-coagulant reactions during water chlorination was investigated by analyses of total product formation potential (TPFP) and disinfection by-product (DBP) distribution as a function of exchanged clay cation, coagulant organic polymer, and reaction time. Montmorillonite clays appeared to act as a catalytic center where the reaction between adsorbed polymer and disinfectant (chlorine) was mediated closely by the exchanged clay cation. The transition-metal cations in clays catalyzed more effectively than other cations the reactions between a coagulant polymer and chlorine, forming a large number of volatile DBPs. The relative catalytic effects of clays/solids followed the order Ti-Mont > Fe-Mont > Cu-Mont > Mn-Mont > Ca-Mont > Na-Mont > quartz > talc. The effects of coagulant polymers on TPFP follow the order nonionic polymer > anionic polymer > cationic polymer. The catalytic role of the clay cation was further confirmed by the observed inhibition in DBP formation when strong chelating agents (o-phenanthroline and ethylenediamine) were added to the clay suspension. Moreover, in the presence of clays, total DBPs increased appreciably when either the reaction time or the amount of the added clay or coagulant polymer increased. For volatile DBPs, the formation of halogenated methanes was usually time-dependent, with chloroform and dichloromethane showing the greatest dependence. ?? 2003 Elsevier Inc. All rights reserved.

  16. Clay mineralogy of the Cretaceous-Tertiary boundary clay. [in search for asteroid ejecta

    NASA Technical Reports Server (NTRS)

    Rampino, M. R.; Reynolds, R. C.

    1983-01-01

    Cretaceous-Tertiary boundary layer clay samples from four localities were subjected to analyses which imply that they are neither mineralogically exotic nor distinct from locally derived clays above and below the boundary. The anomalous iridium-rich ejecta component predicted by the asteroid impact scenario of Alvarez et al (1980) was not detected. It is proposed that volcanic material be considered as an explanation of the geochemical anomalies of the Cretaceous-Tertiary boundary. A model which involves a period of intense volcanism at the end of the Cretaceous would generate a variety of climatic and biological effects consonant with the geologic history of that period.

  17. CO2 adsorption isotherm on clay minerals and the CO2 accessibility into the clay interlayer

    NASA Astrophysics Data System (ADS)

    Gensterblum, Yves; Bertier, Pieter; Busch, Andreas; Rother, Gernot; Krooß, Bernhard

    2013-04-01

    Large-scale CO2 storage in porous rock formations at 1-3 km depth is seen as a global warming mitigation strategy. In this process, CO2 is separated from the flue gas of coal or gas power plants, compressed, and pumped into porous subsurface reservoirs with overlying caprocks (seals). Good seals are mechanically and chemically stable caprocks with low porosity and permeability. They prevent leakage of buoyant CO2 from the reservoir. Caprocks are generally comprised of thick layers of shale, and thus mainly consist of clay minerals. These clays can be affected by CO2-induced processes, such as swelling or dissolution. The interactions of CO2 with clay minerals in shales are at present poorly understood. Sorption measurements in combination scattering techniques could provide fundamental insight into the mechanisms governing CO2-clay interaction. Volumetric sorption techniques have assessed the sorption of supercritical CO2 onto coal (Gensterblum et al., 2010; Gensterblum et al., 2009), porous silica (Rother et al., 2012a) and clays as a means of exploring the potential of large-scale storage of anthropogenic CO2 in geological reservoirs (Busch et al., 2008). On different clay minerals and shales, positive values of excess sorption were measured at gas pressures up to 6 MPa, where the interfacial fluid is assumed to be denser than the bulk fluid. However, zero and negative values were obtained at higher densities, which suggests the adsorbed fluid becomes equal to and eventually less dense than the corresponding bulk fluid, or that the clay minerals expand on CO2 charging. Using a combination of neutron diffraction and excess sorption measurements, we recently deduced the interlayer density of scCO2 in Na-montmorillonite clay in its single-layer hydration state (Rother et al., 2012b), and confirmed its low density, as well as the expansion of the basal spacings. We performed neutron diffraction experiments at the FRMII diffractometer on smectite, kaolinite and illite

  18. Catalytic Wastewater Treatment Using Pillared Clays

    NASA Astrophysics Data System (ADS)

    Perathoner, Siglinda; Centi, Gabriele

    After introduction on the use of solid catalysts in wastewater treatment technologies, particularly advanced oxidation processes (AOPs), this review discussed the use of pillared clay (PILC) materials in three applications: (i) wet air catalytic oxidation (WACO), (ii) wet hydrogen peroxide catalytic oxidation (WHPCO) on Cu-PILC and Fe-PILC, and (iii) behavior of Ti-PILC and Fe-PILC in the photocatalytic or photo-Fenton conversion of pollutants. Literature data are critically analyzed to evidence the main direction to further investigate, in particularly with reference to the possible practical application of these technologies to treat industrial, municipal, or agro-food production wastewater.

  19. What makes a natural clay antibacterial?

    USGS Publications Warehouse

    Williams, Lynda B.; Metge, David W.; Eberl, Dennis D.; Harvey, Ronald W.; Turner, Amanda G.; Prapaipong, Panjai; Port-Peterson, Amisha T.

    2011-01-01

    Chemical analyses of E. coli killed by aqueous leachates of an antibacterial clay show that intracellular concentrations of Fe and P are elevated relative to controls. Phosphorus uptake by the cells supports a regulatory role of polyphosphate or phospholipids in controlling Fe2+. Fenton reaction products can degrade critical cell components, but we deduce that extracellular processes do not cause cell death. Rather, Fe2+ overwhelms outer membrane regulatory proteins and is oxidized when it enters the cell, precipitating Fe3+ and producing lethal hydroxyl radicals.

  20. Utilization of clay wastes containing boron as cement additives

    SciTech Connect

    Oezdemir, Mine; Oeztuerk, Nese Uygan

    2003-10-01

    The utilization of clay wastes (CW) containing boron as cement additives was investigated. The effect of CW on mechanical and chemical properties of cement prepared by adding CW to clinker and gypsum was determined. The results obtained were compared with Portland cement properties and Turkish standards (TS) values. It was determined that the first clay waste (CW1) and the second clay waste (CW2) may be used as cement additives up to 5% and 10%, respectively.

  1. 86. Photocopied August 1978. CLAY RAMMING EQUIPMENT IN OPERATION IN ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    86. Photocopied August 1978. CLAY RAMMING EQUIPMENT IN OPERATION IN THE POWER HOUSE IN 1910. A PILE OF CLAY USED TO FILL THE WASHED-OUT AREAS BENEATH THE FOUNDATIONS IS SHOWN IN THE CENTER OF THE ILLUSTRATION BESIDE THE FILLER PIPE. THE WEIGHT USED TO FORCE THE CLAY DOWN UNDER THE FOUNDATIONS IS SHOWN PRESSING ON THE PLUNGER PIPE. (542) - Michigan Lake Superior Power Company, Portage Street, Sault Ste. Marie, Chippewa County, MI

  2. Clays as dietary supplements for swine: A review.

    PubMed

    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. PMID:26301092

  3. Dynamics of Water Confined in Synthetic Saponite Clays

    SciTech Connect

    Prabhudesai, S. A.; Sharma, V. K.; Mitra, S.; Mukhopadhyay, R.; Chakrabarty, D.; Vicente, Miguel A.

    2011-07-15

    The dynamics of water in two synthetic saponite clays (treated by microwave) with different interlayer spacing has been studied using the quasielastic neutron scattering technique. A model in which the molecules undergo random jump diffusion describes the dynamics of water in both clays. The dynamics of water confined in both saponite clays considered here is found to be hindered in comparison to the bulk phase. It is found that diffusivity increases for samples having higher interlayer spacing.

  4. Clay exfoliation and polymer/clay aerogels by supercritical carbon dioxide

    NASA Astrophysics Data System (ADS)

    Longo, Simona; Mauro, Marco; Daniel, Christophe; Galimberti, Maurizio; Guerra, Gaetano

    2013-11-01

    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.

  5. Clay exfoliation and polymer/clay aerogels by supercritical carbon dioxide

    PubMed Central

    Longo, Simona; Mauro, Marco; Daniel, Christophe; Galimberti, Maurizio; Guerra, Gaetano

    2013-01-01

    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. PMID:24790956

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

    PubMed

    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. PMID:26435008

  7. Astronaut Clay Anderson Speaks With S.C. Students

    NASA Video Gallery

    From NASA's International Space Station Mission Control Center, NASA astronaut Clay Anderson participates in a Digital Learning Network (DLN) event with students at Crayton Middle School, Columbia,...

  8. Epoxy nanocomposites based on high temperature pyridinium-modified clays.

    PubMed

    Zhang, Qingxin; Naito, Kimiyoshi; Qi, Ben; Kagawa, Yutaka

    2009-01-01

    Polymer/clay nanocomposites are generally fabricated by thermal curing or melt compounding at elevated temperatures, however the thermal stability of common alkyl ammonium treated clays is poor and decomposition occurs inevitably during high temperature processing. In this study, we modified clays with an aromatic pyridinium salt. Thermogravimetric analysis (TGA) showed that the onset degradation temperature (Td(onset)) and maximum decomposition temperature (Td(max)) of the pyridinium treatment clays was up to 310 and 457 degrees C respectively implying high thermal stability. The thermal decomposition behaviour of the pyridinium modified clays was discussed. A series of epoxy/clay nanocomposites were synthesized using a diglycidyl ether of bisphenol A (DGEBA) epoxy and diethyltoluene diamine (DETDA). The morphology of epoxy/clay nanocomposites was characterized with wide angle X-ray diffraction (WAXD) and transmission electron microscope (TEM), and intercalated structures were observed. The storage modulus of epoxy was increased but glass transition temperature was decreased with clay incorporation. The effects of clays on glass transition temperature (Tg) of epoxy were also discussed. PMID:19441298

  9. Engineering properties of cement/lime-stabilized Egyptian soft clay

    NASA Astrophysics Data System (ADS)

    Mansour, M. A.; Samieh, A. M.; Matter, H. E.

    2015-09-01

    Soft clay formations are extensively located in many coastal areas around the world. The significant high compressibility and low shear strength of these formations impose challenging engineering problems. The deep cement/lime-mix-in-place method is one of the ground improvement techniques exhibiting successful use in stabilizing soft clay. Analysis and design of the deep mixing systems necessitate the identification of the additive content, the proportions of the lime to cement and the characteristics of the stabilized clay. This paper investigates experimentally the influence of adding lime and cement or cement alone, as stabilizing additives, on the engineering behavior of an Egyptian soft clay extracted from the north delta region. A series of laboratory tests were carried out considering, different additive contents of 8, 10, 12, and 14% of the dry weight, with different proportions of lime to cement of 50:50, 25:75 and 0:100. A series of unconfined compression strength tests were performed after different periods; one week, four weeks and 8 weeks, to assess the effect of curing period on the stabilized clay response. In addition, one dimensional consolidation tests were carried out to evaluate the compressibility properties of the stabilized clay. This study declared that the use of an additive content in the range of 12% and more is recommended to improve the characteristics of the considered Egyptian clay. It was pointed out that addition of lime and cement to soft clay significantly increases the strength characteristics and significantly reduces the compressibility characteristics of such clay.

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

    NASA Astrophysics Data System (ADS)

    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. Prions, Radionuclides and Clays: Impact of clay interlayer "acidity" on toxic compound speciation

    NASA Astrophysics Data System (ADS)

    Charlet, L.; Hureau, C.; Sobolev, O.; Cuello, G.; Chapron, Y.

    2007-05-01

    The physical and chemical processes that are the basis of contaminant retardation in clay rich medium, such as soil or nuclear waste repository, have been studied at the molecular level by a combination of molecular dynamics (MD), electron paramagnetic spectroscopy (EPR) and neutron diffraction with isotopic substitution (NDIS). The speciation of contaminants such as Sm, a radionuclide analogue, and Cu, bound to Prion protein (PrP), has been studied upon adsorption in clay interlayers. We used as molecular probe the P5-Cu(II) complex, where the P5 pentapeptide(92-96 PrP residues) represents one of the five Cu(II) binding site present in PrP, the key protein involved in diseases known as transmissible spongiform encephalopathies. In both cases, the pH of the interlayer has been inferred from the metal ion coordination, here used as a molecular reporter. In circum neutral pH waters, samarium is present as Sm(OH)3° species and should not be adsorbed in clay interlayer by "cation exchange" unless its hydrolysis is altered. Samarium NDIS results indicate that whether the number of oxygen nearest neighbours varies only from 8.5 to 7, as Sm penetrates the interlayer, the number of hydrogen nearest neighbours drops from 12 to 6. The high affinity of clay for Sm shows that a change in Sm hydrolysis occurs in the clay interlayer, but is directly followed by the formation of a surface complex with montmorillonite siloxane plane functional groups which prevents the determination of a "local pH". Conversely, has been found to be a much more sensitive interlayer water pH probe. and this peptide domain is involved in the misfolding of the protein,a transconformation which may lead to the pathogenic PrPSc form. We have therefore studied by EPR spectroscopy the adsorption of Cu(II)-P5 complexes on montmorillonite, and found the clay to have a large and selective adsorption capacity for the various [Cu(P5)H-n](2-n)+ complexes where n is the number of deprotonated amido function

  12. Visual characteristics of clay target shooters.

    PubMed

    Abernethy, B; Neal, R J

    1999-03-01

    A comprehensive battery of standardised visual tests was administered to 11 skilled and 12 novice clay target shooters in an attempt to determine the distinctive visual characteristics of expert performers in this sport. The static and dynamic visual acuity, ocular muscle balance, ocular dominance, depth perception and colour vision of each of the subjects was measured in addition to their performance on simple and choice reaction time, peripheral response time, rapid tachistoscopic detection, coincidence timing and eye movement skills tasks. Expert superiority was observed on the simple reaction time measure only, and the novices actually outperformed the skilled subjects on a number of the other visual measures (viz., static acuity at near distance, dynamic acuity, vertical ocular muscle balance, choice reaction time and rapid target detection discriminability). Scores on all measures for both groups were within the expected normal range indicating that normal and not necessarily above-average basic visual functioning is sufficient to support skilled clay target shooting. An important implication of the finding that skilled shooters are not characterised by supranormal levels of basic visual functioning is the recognition that any attempt to improve shooting performance through training of general attributes of vision to supranormal levels is likely to be unproductive. PMID:10331472

  13. Quantum-chemical modeling of smectite clays

    NASA Technical Reports Server (NTRS)

    Aronowitz, S.; Coyne, L.; Lawless, J.; Rishpon, J.

    1982-01-01

    A self-consistent charge extended Hueckel program is used in modeling isomorphic substitution of Al(3+) by Na(+), K(+), Mg(2+), Fe(2+), and Fe(3+) in the octahedral layer of a dioctahedral smectite clay, such as montmorillonite. Upon comparison of the energies involved in the isomorphic substitution, it is found that the order for successful substitution is as follows: Al(3+), Fe(3+), Mg(2+), Fe(2+), Na(+), which is equivalent to Ca(2+), and then K(+). This ordering is found to be consistent with experimental observation. The calculations also make it possible to determine the possible penetration of metal ions into the clay's 2:1 crystalline layer. For the cases studied, this type of penetration can occur at elevated temperatures into regions where isomorphic substitution has occurred with metal ions that bear a formal charge of less than 3+. The computed behavior of the electronic structure in the presence of isomorphic substitution is found to be similar to behavior associated with semiconductors.

  14. The washability of lignites for clay removal

    SciTech Connect

    Oteyaka, B.; Yamik, A.; Ucar, A.; Sahbaz, O.; Demir, U.

    2008-07-01

    In the washability research of the Seyitomer Lignites (Kutahya-Turkey), with lower calorific value (1,863 kcal/kg) and high ash content (51.91%), by heavy medium separation, it was found out that middling clay in the coal had an effect to change the medium density. To prevent this problem, a trommel sieve with 18 and 5 mm aperture diameter was designed, and the clay in the coal was tried to be removed using it before the coal was released to heavy medium. Following that, the obtained coal in -100 + 18 mm and -18 + 5 mm fractions was subjected to sink and float test having 1.4 gcm{sup -3} and 1.7 gcm{sup -3} medium densities (-5 mm fraction will be evaluated in a separate work). Depending on the raw coal, with the floating of -100 + 18 mm and -18 + 5 mm size fraction in 1.4 gcm{sup -3} medium density, clean coal with 60.10% combustible matter recovery, 19.12% ash, and 3,150 kcal/kg was obtained. Also floating of the samples sinking in 1.4 gcm{sup -3} in the medium density (1.7 gcm{sup -3}), middling with 18.70% combustible matter recovery, 41.93% ash, 2,150 kcal/kg, and tailing having 78.31% ash were obtained.

  15. Can clays ensure nuclear waste repositories?

    PubMed Central

    Zaoui, A.; Sekkal, W.

    2015-01-01

    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. PMID:25742950

  16. Can clays ensure nuclear waste repositories?

    PubMed

    Zaoui, A; Sekkal, W

    2015-01-01

    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. PMID:25742950

  17. Can clays ensure nuclear waste repositories?

    NASA Astrophysics Data System (ADS)

    Zaoui, A.; Sekkal, W.

    2015-03-01

    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.

  18. Organically modified clay removes oil from water

    SciTech Connect

    Alther, G.R.

    1995-12-31

    When bentonite or other clays and zeolite are modified with quaternary amines, they become organophilic. Such modified bentonites are used to remove mechanically emulsified oil and grease, and other sparingly soluble organics. Types of oil found in water can include fats, lubricants, cutting fluids, heavy hydrocarbons such as tars, grease, crude oil, diesel oils; and light hydrocarbons such as kerosene, jet fuel, and gasoline. If the organoclay is granulated, it is placed into a liquid phase carbon filter vessel to remove FOGs (Free Oil and Grease) and chlorinated hydrocarbons. In this application the clay is mixed with anthrazite to prevent early plugging of the filter by oil or grease droplets. In batch systems a powdered organoclay is employed. Organoclay removes mechanically emulsified oil and grease at 5--7 times the rate of activated carbon, or 50% of its dry weight. Oil and grease and other large sparingly soluble chlorinated hydrocarbons and NOMs (Natural Organic Matter) blind the pores of activated carbon (and ion-exchange resins), reducing its effectiveness significantly. It is therefore economically advantageous for the end user to prepolish the water before it enters carbon vessels. Operating costs can often be reduced by 50% or more.

  19. Geosynthetic clay liners - slope stability field study

    SciTech Connect

    Carson, D.A.; Daniel, D.E.; Koerner, R.M.; Bonaparte, R.

    1997-12-31

    A field research project was developed to examine the internal shear performance of geosynthetic clay liners (GCLs). Several combinations of cross sections were assembled using GCL materials that were available at the time of project initiation. The cross sections utilized were intended to simulate landfill cover applications. Thirteen (13) resulting test plots were constructed on two different slope angles, and each plot is instrumented for physical displacement and soil moisture characteristics. Test plots were constructed in a manner that dictated the shear plane in the clay portion of the GCL product. The project purpose is to assess field performance and to verify design parameters associated with the application of GCLs in waste containment applications. Interim research data shows that test slopes on 2H:1V show global deformation, but little internal shear evidence, and the 3H:1V slopes show little deformation at approximately 650 days. The research is ongoing, and this paper presents the most recent information available from the project.

  20. Naphthene upgrading with pillared synthetic clay catalysts

    SciTech Connect

    Sharma, R.K.; Olson, E.S.

    1995-12-31

    Catalytic hydrotreatment of methylcyclohexane was investigated to model upgrading of coal-derived naphthenes. Nickel-substituted synthetic mica montmorillonite (NiSMM), alumina-pillared NiSMM and Zirconia-pillared NiSMM were prepared and tested for hydrocracking and hydroisomerization of methylcyclohexane. Infrared and thermal desorption studies of the pyridine-adsorbed catalysts indicated the presence of Lewis and Bronsted acid sites. Total acidity and surface area increased with pillaring of NiSMM with polyoxy aluminum and polyoxy zirconium cations. Methylcyclohexane was reacted with these catalysts under a variety of conditions. Pillared clays gave higher gas yields and higher hydrocracking but lower hydroisomerization activity than nonpillared clay. The majority of the products were branched alkanes (isoparaffinic). These catalysts effectively use hydrogen as indicated by the minimal formation of aromatic hydrocarbons, coke, or other oligomeric materials. The effect of various operating conditions, i.e., reaction temperature, contact time, H{sub 2} pressure, and catalyst, on the product distribution will be described.

  1. Surface modification of montmorillonite on surface Acid-base characteristics of clay and thermal stability of epoxy/clay nanocomposites.

    PubMed

    Park, Soo-Jin; Seo, Dong-Il; Lee, Jae-Rock

    2002-07-01

    In this work, the effect of surface treatments on smectitic clay was investigated in surface energetics and thermal behaviors of epoxy/clay nanocomposites. The pH values, X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR) were used to analyze the effect of cation exchange on clay surface and the exfoliation phenomenon of clay interlayer. The surface energetics of clay and thermal properties of epoxy/clay nanocomposites were investigated in contact angles and thermogravimetric analysis (TGA), respectively. From the experimental results, the surface modification of clay by dodecylammonium chloride led to the increases in both distance between silicate layers of about 8 A and surface acid values, as well as in the electron acceptor component (gamma(+)(s)) of surface free energy, resulting in improved interfacial adhesion between basic (or electron donor) epoxy resins and acidic (electron acceptor) clay interlayers. Also, the thermal stability of nanocomposites was highly superior to pure epoxy resin due to the presence of the well-dispersed clay nanolayer, which has a barrier property in a composite system. PMID:16290714

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

    PubMed

    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

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

    NASA Technical Reports Server (NTRS)

    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.

  4. INTERIOR VIEW ON SEVENTH FLOOR ALONG EAST (CLAY STREET) FRONT. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    INTERIOR VIEW ON SEVENTH FLOOR ALONG EAST (CLAY STREET) FRONT. TYPICAL INTERIOR CONDITIONS OF PARTIAL DEMOLITION; SUSPENDED CEILING AND MOVABLE PARTITION WALLS REMOVED, REMAINS OF DEMOLISHED SHEET METAL CORNICE FROM BUILDING EXTERIOR VISIBLE ON FLOOR - John Breuner & Company Building, 1515 Clay Street, Oakland, Alameda County, CA

  5. INTERACTIONS BETWEEN ORGANIC COMPOUNDS AND CYCLODEXTRIN-CLAY SYSTEMS

    EPA Science Inventory

    Computational and experimental techniques are combined in order to better understand interactions involving organic compounds and cyclodextrin (CD)-clay systems. CD-clay systems may have great potential in the containment of organic contaminants in the environment. This study w...

  6. The surface modification of clay particles by RF plasma technique

    NASA Astrophysics Data System (ADS)

    Lee, Sang-Keol

    In this study, the surface coatings of ball clay, organoclay and exfoliated clay prepared by sol-gel process were done by RF plasma polymerization to improve the surface activity of the clay filler. Characterization of the above plasma-treated clays has been carried out by various techniques. The effects of plasma-treated clays as substitute of carbon black in styrene-butadiene rubber (SBR) and ethylene-propylene-diene monomer (EPDM) on the curing and mechanical properties were investigated. After plasma treatment, the tensile properties of organo and exfoliated clay were not unsatisfactory to that of carbon black filler system. Moreover, only 10 phr filler loading of plasma-treated organoclay in EPDM vulcanizates showed better results than 40 phr filler loading of carbon black in EPDM vulcanizates. The main objective of this study was to verify the applicability of the plasma technique for modifying clay surfaces for their use in the tire manufacturing industry. Another purpose was to reveal the advantage of the plasma technique used to obtain modified-clay and improved properties that those materials can display.

  7. EFFECTS OF SELECTED INORGANIC LEACHATES ON CLAY PERMEABILITY

    EPA Science Inventory

    Hydraulic conductivity test results for three field clays exposed to two inorganic chemicals are documented. The hydraulic conductivities of clays exposed to waste chemicals is an important consideration in the selection of a liner material for a hazardous waste containment facil...

  8. Adsorption coefficients for TNT on soil and clay minerals

    NASA Astrophysics Data System (ADS)

    Rivera, Rosángela; Pabón, Julissa; Pérez, Omarie; Muñoz, Miguel A.; Mina, Nairmen

    2007-04-01

    To understand the fate and transport mechanisms of TNT from buried landmines is it essential to determine the adsorption process of TNT on soil and clay minerals. In this research, soil samples from horizons Ap and A from Jobos Series at Isabela, Puerto Rico were studied. The clay fractions were separated from the other soil components by centrifugation. Using the hydrometer method the particle size distribution for the soil horizons was obtained. Physical and chemical characterization studies such as cation exchange capacity (CEC), surface area, percent of organic matter and pH were performed for the soil and clay samples. A complete mineralogical characterization of clay fractions using X-ray diffraction analysis reveals the presence of kaolinite, goethite, hematite, gibbsite and quartz. In order to obtain adsorption coefficients (K d values) for the TNT-soil and TNT-clay interactions high performance liquid chromatography (HPLC) was used. The adsorption process for TNT-soil was described by the Langmuir model. A higher adsorption was observed in the Ap horizon. The Freundlich model described the adsorption process for TNT-clay interactions. The affinity and relative adsorption capacity of the clay for TNT were higher in the A horizon. These results suggest that adsorption by soil organic matter predominates over adsorption on clay minerals when significant soil organic matter content is present. It was found that, properties like cation exchange capacity and surface area are important factors in the adsorption of clayey soils.

  9. Sorption Charecterization of Radonuclides on Clays in Yucca Mountain Alluvium

    SciTech Connect

    M. Ding; P.W. Reimus; S. Chipera; C. Scism

    2006-03-17

    Sorption of {sup 237}Np(V) and {sup 233}U(VI) was measured on clays separated from Yucca Mountain alluvium as a function of solution pH and aqueous actinide concentrations. The results indicate that sorption of U and Np on the separated clay fraction depends strongly on solution pH. Np sorption on clays increases slowly with increasing pH from 3 to 7. Above pH 7, Np sorption on clays increases rapidly up to a pH of about 10. On the other hand, U sorption on clays reaches it maximum at a pH of about 6, with sorption decreasing as pH increases from 6 to 8 and then increasing again as pH increases further from 8 to about 10. The results suggest that a Freundlich isotherm can be used to describe U and Np sorption on clays at pH above 5.5. The results of this study indicate that clay minerals play a very important role in the sorption of U and Np on Yucca Mountain alluvium. Indeed, the clay content of the alluvium is probably considerably more important than water chemistry in predicting the ability of the alluvium to attenuate the transport of these radionuclides.

  10. Learning of Cross-Sectional Anatomy Using Clay Models

    ERIC Educational Resources Information Center

    Oh, Chang-Seok; Kim, Ji-Young; Choe, Yeon Hyeon

    2009-01-01

    We incorporated clay modeling into gross anatomy and neuro-anatomy courses to help students understand cross-sectional anatomy. By making clay models, cutting them and comparing cut surfaces to CT and MR images, students learned how cross-sectional two-dimensional images were created from three-dimensional structure of human organs. Most students…

  11. Adsorption of zearalenone to Japanese acid clay and influencing factors.

    PubMed

    Sasaki, Risa; Takahashi, Noriyuki; Sakao, Kazunori; Goto, Tetsuhisa

    2014-02-01

    Zearalenone (ZEA) mainly contaminates grains such as corn and wheat, causing damage to livestock through ingestion of contaminated feed. Recently, various clays have been added to the feed to adsorb mycotoxins and to prevent mycotoxicosis of animals fed contaminated feeds. However the adsorption mechanism of the mycotoxin to clay is not well understood. In this study, a method to analyze the level of adsorption of ZEA to clay was developed using Japanese acid clay. Changes to the amount of the clay, concentration of ZEA, shaking time, and other parameters were evaluated to determine their influence on adsorption. The adsorption isotherms were also developed. Under conditions that mimic the gastrointestinal tract of swine, 100 % of ZEA was adsorbed to clay at a pH equivalent to the stomach, while the level of desorption under intestinal basic conditions was 1.8 %. Thus Japanese acid clay has a high ability to absorb ZEA with very little desorption under gastrointestinal conditions of the swine. Isothermal analysis suggests that the Japanese acid clay is potentially highly efficacious as a ZEA adsorbent. PMID:24194382

  12. Clay and Magnetite Formation at Yellowknife Bay, Mars

    NASA Astrophysics Data System (ADS)

    Bridges, J. C.; Schwenzer, S. P.; Leveille, R.; Westall, F.; Wiens, R. C.; Mangold, N.; Bristow, T.; Edwards, P.; Berger, G.

    2014-09-01

    Sheepbed mudstone contains a clay-magnetite assemblage formed by dissolution of approximately 70% amorphous phase, 20% olivine, 10% host rock mixture, by a pore fluid at moderate W/R ratio. The clay is similar to Lafayette's ferric saponite and gel.

  13. Triazine adsorption by saponite and beidellite clay minerals.

    PubMed

    Aggarwal, Vaneet; Li, Hui; Teppen, Brian J

    2006-02-01

    We investigated the sorption of three triazine herbicides (atrazine, simazine, and metribuzin) by saponite and beidellite clay minerals saturated with K+, Cs+, Na+, and Ca2+. Saponite clay sorbed a larger fraction of each pesticide from aqueous solution than did beidellite clay. The lower cation-exchange capacity in saponite compared to that in beidellite presumably results in a less crowded interlayer, with more siloxane surface being available for adsorption. Generally, Cs-saturated clays sorbed more triazines than did clays saturated by K+, Na+, or Ca2+. We attribute this to the smaller hydrated radius of Cs+, which again increases the siloxane surface that is available for sorption. Furthermore, the relatively weak hydration of Cs+ reduces the swelling of clay interlayers, thus making sorption domains less hydrated and more receptive to hydrophobic molecules. The Cs-saponite manifested a sorption of more than 1% atrazine by weight above equilibrium concentrations of 6 mg/L, which to our knowledge is the largest sorption of neutral atrazine from water yet reported for an inorganic sorbent. Molecular dynamics simulations indicate that atrazine interacts both with clay basal planes and with multiple cations in the clay interlayer. PMID:16519299

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

    ERIC Educational Resources Information Center

    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)

  15. Mapping and Quantifying Surface Charges on Clay Nanoparticles.

    PubMed

    Liu, Jun; Gaikwad, Ravi; Hande, Aharnish; Das, Siddhartha; Thundat, Thomas

    2015-09-29

    Understanding the electrical properties of clay nanoparticles is very important since they play a crucial role in every aspect of oil sands processing, from bitumen extraction to sedimentation in mature fine tailings (MFT). Here, we report the direct mapping and quantification of surface charges on clay nanoparticles using Kelvin probe force microscopy (KPFM) and electrostatic force microscopy (EFM). The morphology of clean kaolinite clay nanoparticles shows a layered structure, while the corresponding surface potential map shows a layer-dependent charge distribution. More importantly, a surface charge density of 25 nC/cm(2) was estimated for clean kaolinite layers by using EFM measurements. On the other hand, the EFM measurements show that the clay particles obtained from the tailings demonstrate a reduced surface charge density of 7 nC/cm(2), which may be possibly attributed to the presence of various bituminous compounds residing on the clay surfaces. PMID:26352908

  16. Learning of cross-sectional anatomy using clay models.

    PubMed

    Oh, Chang-Seok; Kim, Ji-Young; Choe, Yeon Hyeon

    2009-01-01

    We incorporated clay modeling into gross anatomy and neuro-anatomy courses to help students understand cross-sectional anatomy. By making clay models, cutting them and comparing cut surfaces to CT and MR images, students learned how cross-sectional two-dimensional images were created from three-dimensional structure of human organs. Most students in a clay modeling group responded positively to this approach, and their average score on CT examination was higher than that of a group that did not use clay models. Clay modeling appears to be a useful supplement to conventional anatomy or radiologic anatomy education. It can be applied to any part of human body, and its effectiveness will be greater when a more complicated understanding of cross-sectional anatomy is required. PMID:19588481

  17. Organic/Inorganic Hybrid Polymer/Clay Nanocomposites

    NASA Technical Reports Server (NTRS)

    Park, Cheol; Connell, John W.; Smith, Joseph G., Jr.

    2003-01-01

    A novel class of polymer/clay nanocomposites has been invented in an attempt to develop transparent, lightweight, durable materials for a variety of aerospace applications. As their name suggests, polymer/ clay nanocomposites comprise organic/ inorganic hybrid polymer matrices containing platelet-shaped clay particles that have sizes of the order of a few nanometers thick and several hundred nanometers long. Partly because of their high aspect ratios and high surface areas, the clay particles, if properly dispersed in the polymer matrix at a loading level of 1 to 5 weight percent, impart unique combinations of physical and chemical properties that make these nanocomposites attractive for making films and coatings for a variety of industrial applications. Relative to the unmodified polymer, the polymer/ clay nanocomposites may exhibit improvements in strength, modulus, and toughness; tear, radiation, and fire resistance; and lower thermal expansion and permeability to gases while retaining a high degree of optical transparency.

  18. Organic-inorganic hybrids from renewable plant oils and clay.

    PubMed

    Uyama, Hiroshi; Kuwabara, Mai; Tsujimoto, Takashi; Nakano, Mitsuru; Usuki, Arimitsu; Kobayashi, Shiro

    2004-03-15

    This study deals with the preparation and properties of a new class of organic-inorganic hybrids from renewable resources. The hybrids were synthesized by an acid-catalyzed curing of epoxidized triglycerides in the presence of an organophilic montmorillonite (a modified clay). The mechanical properties were improved by the incorporation of clay in the oil-based polymer matrix. The reinforcement effect due to the addition of clay was confirmed by dynamic viscoelasticity analysis. The hybrids showed relatively high thermal stability. The co-curing of epoxidized soybean and linseed oils in the presence of clay produced hybrids with controlled mechanical and coating properties. The barrier property of the hybrid towards water vapor was superior to that of the oil polymer. The development of the present hybrids consisting of inexpensive renewable resources, triglyceride and clay is expected to contribute to global sustainability. PMID:15468227

  19. Prolonged triboluminescence in clays and other minerals

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

    Samples of various clays and minerals were ground or fractured and monitored with a liquid scintillation spectrometer in order to obtain triboluminescent decay curves. Kaolinite samples displayed several million counts/min after grinding, with a surface area emission estimated at tens of billions of photons/sq cm of surface. The photon production rates varied with the origin of the sample, and kaolinite continually yielded higher production rates than bentonite. The addition of water to the samples slightly increased the count rate of emitted light, while the addition of the fluorescent molecule substance tryptofan significantly enhanced the count rate. Freezing smears of kaolinite and montmorillonite in liquid nitrogen and in a salt ice mixture also induced triboluminescence in the montmorillonite. A possible connection between powdery triboluminescent materials formed in mining industries and respiratory disorders among miners is suggested.

  20. Directional plasticity of clay showing instability

    NASA Astrophysics Data System (ADS)

    Fortuna, Sonia

    2010-06-01

    A graphical approach is used to sketch the field of small plastic strains (epsilon < 0.1 %) of Pisa clay along different axi-symmetric stress paths associated to a partial confining stress reduction. Within the classic framework of elasto-plasticity, volumetric and deviatoric plastic strains contours are determined from data obtained from triaxial tests, assuming a cross-anisotropic hypo-elastic formulation calibrated on a wide set of tests and with non linear evolution of the elastic moduli calibrated along a quasi-1D swelling stress path. The evolutions of the plastic strains and of the plastic strain vectors are shown along the stress path directly explored with tests and along virtual paths interpolated from the actual data along intermediate directions at various strain levels.

  1. Sorption Energy Maps of Clay Mineral Surfaces

    SciTech Connect

    Cygan, Randall T.; Kirkpatrick, R. James

    1999-07-19

    A molecular-level understanding of mineral-water interactions is critical for the evaluation and prediction of the sorption properties of clay minerals that may be used in various chemical and radioactive waste disposal methods. Molecular models of metal sorption incorporate empirical energy force fields, based on molecular orbital calculations and spectroscopic data, that account for Coulombic, van der Waals attractive, and short-range repulsive energies. The summation of the non-bonded energy terms at equally-spaced grid points surrounding a mineral substrate provides a three dimensional potential energy grid. The energy map can be used to determine the optimal sorption sites of metal ions on the exposed surfaces of the mineral. By using this approach, we have evaluated the crystallographic and compositional control of metal sorption on the surfaces of kaolinite and illite. Estimates of the relative sorption energy and most stable sorption sites are derived based on a rigid ion approximation.

  2. Complex resistivity signatures of ethanol in sand-clay mixtures.

    PubMed

    Personna, Yves Robert; Slater, Lee; Ntarlagiannis, Dimitrios; Werkema, Dale; Szabo, Zoltan

    2013-06-01

    We performed complex resistivity (CR) measurements on laboratory columns to investigate changes in electrical properties as a result of varying ethanol (EtOH) concentration (0% to 30% v/v) in a sand-clay (bentonite) matrix. We applied Debye decomposition, a phenomenological model commonly used to fit CR data, to determine model parameters (time constant: τ, chargeability: m, and normalized chargeability: mn). The CR data showed a significant (P≤0.001) time-dependent variation in the clay driven polarization response (~12 mrad) for 0% EtOH concentration. This temporal variation probably results from the clay-water reaction kinetics trending towards equilibrium in the sand-clay-water system. The clay polarization is significantly suppressed (P≤0.001) for both measured phase (ϕ) and imaginary conductivity (σ″) with increasing EtOH concentration. Normalized chargeability consistently decreases (by up to a factor of ~2) as EtOH concentration increases from 0% to 10% and 10 to 20%, respectively. We propose that such suppression effects are associated with alterations in the electrical double layer (EDL) at the clay-fluid interface due to (a) strong EtOH adsorption on clay, and (b) complex intermolecular EtOH-water interactions and subsequent changes in ionic mobility on the surface in the EDL. Changes in the CR data following a change of the saturating fluid from EtOH 20% to plain water indicate strong hysteresis effects in the electrical response, which we attribute to persistent EtOH adsorption on clay. Our results demonstrate high sensitivity of CR measurements to clay-EtOH interactions in porous media, indicating the potential application of this technique for characterization and monitoring of ethanol contamination in sediments containing clays. PMID:23603518

  3. Adding Clays to Sandy Soils to Increase Carbon Storage

    NASA Astrophysics Data System (ADS)

    Harper, R. J.; Sochacki, S. J.

    2011-12-01

    Soil carbon storage is often related to clay content and mineralogy. For example, in a dryland farming area (300 mm/year annual rainfall) of Western Australia, carbon storage increased systematically with increasing clay content. Carbon storage in the surface 0.1 m was 42.5 Mg CO2-e/ha in soils with 1.7% clay compared to 99.1 Mg CO2-e/ha for soils with 9.1% clay. Similar results are evident in other data-sets, with carbon storage being related to site water balance, clay content and soil chemical fertility. We thus investigated whether soil carbon storage could be manipulated in sandy soils by adding clay. Clays are often added to farmed sandy soils to overcome water repellency and to reduce nutrient losses by leaching, but are not considered as a carbon management tool. The combined effects can improve plant productivity and thus carbon inputs to soil carbon pools. Bauxite processing residue (10% clay) had been applied in 1982 to sandy soils at different rates in an area with 760 mm/year annual rainfall. Application of 25 Mg clay/ha resulted in an increase in soil carbon content of 47.7 Mg CO2-e/ha. Soils were sampled to a depth of 0.3 m, with most (65%) of the increase being in the surface 0.1 m. Globally, there are large areas of sandy soils occurring across several soil taxonomic orders. In this presentation we describe the implications of clay amendments for increasing the carbon storage in such soils, and suggest areas of further investigation.

  4. Fractal dimensions of flocs between clay particles and HAB organisms

    NASA Astrophysics Data System (ADS)

    Wang, Hongliang; Yu, Zhiming; Cao, Xihua; Song, Xiuxian

    2011-05-01

    The impact of harmful algal blooms (HABs) on public health and related economics have been increasing in many coastal regions of the world. Sedimentation of algal cells through flocculation with clay particles is a promising strategy for controlling HABs. Previous studies found that removal efficiency (RE) was influenced by many factors, including clay type and concentration, algal growth stage, and physiological aspects of HAB cells. To estimate the effect of morphological characteristics of the aggregates on HAB cell removal, fractal dimensions were measured and the RE of three species of HAB organism, Heterosigma akashiwo, Alexandrium tamarense, and Skeletonema costatum, by original clay and modified clay, was determined. For all HAB species, the modified clay had a higher RE than original clay. For the original clay, the two-dimensional fractal dimension ( D 2) was 1.92 and three-dimensional fractal dimension ( D 3) 2.81, while for the modified clay, D 2 was 1.84 and D 3 was 2.50. The addition of polyaluminum chloride (PACl) lead to a decrease of the repulsive barrier between clay particles, and resulted in lower D 2 and D 3. Due to the decrease of D 3, and the increase of the effective sticking coefficient, the flocculation rate between modified clay particles and HAB organisms increased, and thus resulted in a high RE. The fractal dimensions of flocs differed in HAB species with different cell morphologies. For example, Alexandrium tamarense cells are ellipsoidal, and the D 3 and D 2 of flocs were the highest, while for Skeletonema costatum, which has filamentous cells, the D 3 and D 2 of flocs were the lowest.

  5. Heteroaggregation of titanium dioxide nanoparticles with natural clay colloids.

    PubMed

    Labille, Jérôme; Harns, Carrie; Bottero, Jean-Yves; Brant, Jonathan

    2015-06-01

    To better understand and predict the fate of engineered nanoparticles in the water column, we assessed the heteroaggregation of TiO2 nanoparticles with a smectite clay as analogues for natural colloids. Heteroaggregation was evaluated as a function of water salinity (10(-3) and 10(-1) M NaCl), pH (5 and 8), and selected nanoparticle concentration (0-4 mg/L). Time-resolved laser diffraction was used, coupled to an aggregation model, to identify the key mechanisms and variables that drive the heteroaggregation of the nanoparticles with colloids. Our data show that, at a relevant concentration, nanoparticle behavior is mainly driven by heteroaggregation with colloids, while homoaggregation remains negligible. The affinity of TiO2 nanoparticles for clay is driven by electrostatic interactions. Opposite surface charges and/or high ionic strength favored the formation of primary heteroaggregates via the attachment of nanoparticles to the clay. The initial shape and dispersion state of the clay as well as the nanoparticle/clay concentration ratio also affected the nature of the heteroaggregation mechanism. With dispersed clay platelets (10(-3) M NaCl), secondary heteroaggregation driven by bridging nanoparticles occurred at a nanoparticle/clay number ratio of greater than 0.5. In 10(-1) M NaCl, the clay was preaggregated into larger and more spherical units. This favored secondary heteroaggregation at lower nanoparticle concentration that correlated to the nanoparticle/clay surface area ratio. In this latter case, a nanoparticle to clay sticking efficiency could be determined. PMID:25913600

  6. Layer Charge of Clay Minerals; Selected papers from the Symposium on Current Knowledge on the Layer Charge of Clay Minerals

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This Special issue contains papers based on the contributions presented during the workshop “Current Knowledge on the Layer Charge of Clay Minerals”, held on September 18 and 19, 2004, in the Smolenice Castle, Slovakia. Layer charge is one of the most important characteristics of clay minerals as it...

  7. Studies of clays and clay minerals using x-ray powder diffraction and the Rietveld method

    SciTech Connect

    Bish, D.L.

    1993-09-01

    The Rietveld method was originally developed (Rietveld, 1967, 1969) to refine crystal structures using neutron powder diffraction data. Since then, the method has been increasingly used with X-ray powder diffraction data, and today it is safe to say that this is the most common application of the method. The method has been applied to numerous natural and synthetic materials, most of which do not usually form crystals large enough for study with single-crystal techniques. It is the ability to study the structures of materials for which sufficiently large single crystals do not exist that makes the method so powerful and popular. It would thus appear that the method is ideal for studying clays and clay minerals. In many cases this is true, but the assumptions implicit in the method and the disordered nature of many clay minerals can limit titsapplicability. This chapter will describe the Rietveld method, emphasizing the assumptions important for the study of disordered materials, and it will outline the potential applications of the method to these minerals. These applications include, in addition to the refinement of crystal structures, quantitative analysis of multicomponent mixtures, analysis of peak broadening, partial structure solution, and refinement of unit-cell parameters.

  8. Thermo Gravimetric and Differential Thermal Analysis of Clay of Western Rajasthan (india)

    NASA Astrophysics Data System (ADS)

    Shekhawat, M. S.

    The paper presents the study of thermo gravimetric and differential thermal analysis of blended clay. Western part of Rajasthan (India) is rich resource of Ball clays and it is mainly used by porcelain, sanitary ware, and tile industry. The quality and grade of clay available in the region vary from one deposit to other. To upgrade the fired colour and strength properties, different variety of clays may be blended together. The paper compares the results of thermal analysis one of blended clay B2 with reference clay of Ukraine which is imported by industries owners. The result revealed that the blended clay is having mineral kaolinite while the Ukrainian clay is Halloysite.

  9. Microbe-Clay Mineral Reactions and Characterization Techniques

    NASA Astrophysics Data System (ADS)

    Dong, H.; Zhang, G.; Ji, S.; Jaisi, D.; Kim, J.

    2008-12-01

    Clays and clay minerals are ubiquitous in soils, sediments, and sedimentary rocks. They play an important role in environmental processes such as nutrient cycling, plant growth, contaminant migration, organic matter maturation, and petroleum production. The changes in the oxidation state of the structural iron in clay minerals, in part, control their physical and chemical properties in natural environments, such as clay particle flocculation, dispersion, swelling, hydraulic conductivity, surface area, cation and anion exchange capacity, and reactivity towards organic and inorganic contaminants. The structural ferric iron [Fe(III)] in clay minerals can be reduced either chemically or biologically. Many different chemical reductants have been tried, but the most commonly used agent is dithionite. Biological reductants are bacteria, including dissimilatory iron reducing prokaryotes (DIRP) and sulfate-reducing bacteria (SRB). A wide variety of DIRP have been used to reduce ferric iron in clay minerals, including mesophilic, thermophilic, and hyperthermophilic prokaryotes. Multiple clay minerals have been used for microbial reduction studies, including smectite, nontronite (iron-rich smectite variety), illite, illite/smectite, chlorite, and their various mixtures. All these clay minerals are reducible by microorganisms under various conditions with smectite (nontronite) being the most reducible. The reduction extent and rate of ferric iron in clay minerals are measured by wet chemistry, and the reduced clay mineral products are typically characterized with chemical methods, X-ray diffraction, scanning and transmission electron microscopy, Mössbauer spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), UV-vis spectroscopy, and synchrotron-based techniques (such as EXAFS). Microbially reduced smectites (nontronites) have been found to be reactive in reducing a variety of organic and inorganic contaminants. Degradable organic contaminants include pesticides

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

    NASA Astrophysics Data System (ADS)

    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

  11. Light reflection visualization to determine solute diffusion into clays

    NASA Astrophysics Data System (ADS)

    Yang, Minjune; Annable, Michael D.; Jawitz, James W.

    2014-06-01

    Light reflection visualization (LRV) experiments were performed to investigate solute diffusion in low-permeability porous media using a well-controlled two-dimensional flow chamber with a domain composed of two layers (one sand and one clay). Two different dye tracers (Brilliant Blue FCF and Ponceau 4R) and clay domains (kaolinite and montmorillonite) were used. The images obtained through the LRV technique were processed to monitor two-dimensional concentration distributions in the low-permeability zone by applying calibration curves that related light intensity to equilibrium concentrations for each dye tracer in the clay. One dimensional experimentally-measured LRV concentration profiles in the clay were found to be in very good agreement with those predicted from a one-dimensional analytical solution, with coefficient of efficiency values that exceeded 0.97. The retardation factors (R) for both dyes were relatively large, leading to slow diffusive penetration into the clays. At a relative concentration C/C0 = 0.1, Brilliant Blue FCF in kaolinite (R = 11) diffused approximately 10 mm after 21 days of source loading, and Ponceau 4R in montmorillonite (R = 7) diffused approximately 12 mm after 23 days of source loading. The LRV experimentally-measured two-dimensional concentration profiles in the clay were also well described by a simple analytical solution. The results from this study demonstrate that the LRV approach is an attractive non-invasive tool to investigate the concentration distribution of dye tracers in clays in laboratory experiments.

  12. Light reflection visualization to determine solute diffusion into clays.

    PubMed

    Yang, Minjune; Annable, Michael D; Jawitz, James W

    2014-06-01

    Light reflection visualization (LRV) experiments were performed to investigate solute diffusion in low-permeability porous media using a well-controlled two-dimensional flow chamber with a domain composed of two layers (one sand and one clay). Two different dye tracers (Brilliant Blue FCF and Ponceau 4R) and clay domains (kaolinite and montmorillonite) were used. The images obtained through the LRV technique were processed to monitor two-dimensional concentration distributions in the low-permeability zone by applying calibration curves that related light intensity to equilibrium concentrations for each dye tracer in the clay. One dimensional experimentally-measured LRV concentration profiles in the clay were found to be in very good agreement with those predicted from a one-dimensional analytical solution, with coefficient of efficiency values that exceeded 0.97. The retardation factors (R) for both dyes were relatively large, leading to slow diffusive penetration into the clays. At a relative concentration C/C0=0.1, Brilliant Blue FCF in kaolinite (R=11) diffused approximately 10 mm after 21 days of source loading, and Ponceau 4R in montmorillonite (R=7) diffused approximately 12 mm after 23 days of source loading. The LRV experimentally-measured two-dimensional concentration profiles in the clay were also well described by a simple analytical solution. The results from this study demonstrate that the LRV approach is an attractive non-invasive tool to investigate the concentration distribution of dye tracers in clays in laboratory experiments. PMID:24657742

  13. SAXS Study of Reversibly Crosslinked Isotactic Polypropylene/clay Nanocomposites

    SciTech Connect

    Bouhelal, S.; Cagiao, M; Benachour, D; Djellouli, B; Rong, L; Hsiao, B; Baltá-Calleja, F

    2010-01-01

    A new route based on reversibly crosslinking reactive extrusion is applied for the development of iPP/clay nanocomposites. Analysis of small-angle X-ray scattering (SAXS) reflections of isotactic polypropylene (iPP)/clay nanocomposites, prepared by two different mixing and chemical crosslinking methods (i.e., conventional and in situ), is presented and results are compared with preceding wide-angle X-ray diffraction (WAXD) results. It is shown that the presence of clay significantly affects the value of long spacing in iPP, as well as the coherence length of lamellar stacks. Results show that the size of the coherently diffracting nanodomains decreases in two stages, first rapidly and then slowly as a function of increasing clay content. This can be attributed to the influence of confined iPP lamellae under the effect of rising number of clay particles. The appearance of the {gamma}-crystalline form in the crosslinked iPP/clay nanocomposites is related with the difficulty in chain folding of iPP chains introduced by the chemical crosslinking process, as well as by the presence of clay particles.

  14. Clay Mineralogy of a Pleistocene Barrier Island, Skidaway Island, GA

    NASA Astrophysics Data System (ADS)

    Shaffer, M.; Shackford, J. K.; Elliott, W. C.; Christensen, B. A.; Freile, D.; Hillier, C.; Horton, B. P.

    2005-05-01

    A dense blue clay underlies various marsh localities near the Skidaway Institute of Oceanography (SKIO). SKIO is located on a Pleistocene barrier island in Georgia. The clay is found in two cores drilled at the high marsh/maritime forest transition zone. It was recovered at a depth of one meter, below unconsolidated marsh sediment. A total of 12 clay samples were collected at 10cm intervals downcore beginning at 100cm, through the clay layer. The thickness of the clay layer is unknown due to core refusal at a heavily iron oxide mottled zone. Samples were examined for the presence of diatoms and foraminifera, neither of which were found to be present, thereby suggesting a non-marine environment, although dissolution may be a factor. Geochemical data also lacks a definite marine signature, thereby confirming the micropaleontological conclusions. Smectite, illite, and kaolinite were found throughout both cores with halloysite present only below a depth of roughly 120cm. These particular clay minerals have been identified in blue clays analyzed in the Carolina Bays of southern North Carolina. Halloysite is typically a metastable phase forming from the weathering of illite to kaolinite, thus the location of the halloysite found in these cores indicates more recent weathering of the parent illite at depth. This is unusual as weathering is normally thought to be more intense closer to the surface. Vermiculite, which is also part of the general weathering scheme of mica, was not identified in the cores based on the behavior of the samples after solvation in ethylene glycol and potassium-saturation. The observed clay assemblage is similar to that of North Carolina Carolina Bays. Carolina Bays are found from Virginia to Georgia, and are found to contain blue clays (Ingram et al., 1959). Morphologically, Carolina Bays are typically elliptical and while the study area is more rounded, this could be due to its modification by an active tidal system.

  15. Variation of elastic moduli of clays with humidity

    NASA Astrophysics Data System (ADS)

    Kuila, U.; Prasad, M.

    2012-12-01

    The elastic moduli of clays are highly variable. The reported values of elastic moduli of clays in the literature provide a large range: ranging from 0.15 GPa to 400 GPa. One of the many probable reasons for this variation is different external experimental environments leading to varied amounts of cations and bound water in the interlayers. The clay structure is affected by the kind of water associated with it: free water and bound water, the water in the interlayer. Smectite and mixed-layered illite-smectite (I-S) are capable of retaining significant electrostatic bound water in excess of 200C and can rapidly adsorb moisture from the air depending upon the humidity conditions. These can lead to the variation in their elastic properties. Prior experimental studies of acoustic velocity measurement in compacted clay pellets showed comparable trends (Figure 1) but different velocities for same reported porosity. This can be attributed to the humidity difference in the lab ambient conditions where the measurements were made. Molecular simulation studies on montmorillonite clays shows similar dependence of Young's Modulus on the hydration state of the clays (Pal Bathija 2009). In this paper, we studied the effect of humidity on the elastic properties of compacted pellets of Na-montmorillonite. This can be achieved by placing the Na-montmorillonite pellets in bell jars containing different saturated salt solutions. These salt solutions are used as a standard for relative humidity measurements. Figure 2 shows an experimental set-up used to the experiment. We will present the results of the variation of elastic properties of clays with varying humidity conditions. Preliminary results suggest that acoustic velocities through the compacted Na-montmorillonite pellet depend on the humidity conditions. The varying amount of interlayer clay-bound water and capillary condensation of water in small micropores in clays with varying humidity conditions resulted in the change in the

  16. Inter-layered clay stacks in Jurassic shales

    NASA Technical Reports Server (NTRS)

    Pye, K.; Krinsley, D. H.

    1983-01-01

    Scanning electron microscopy in the backscattered electron mode is used together with energy-dispersive X-ray microanalysis to show that Lower Jurassic shales from the North Sea Basin contain large numbers of clay mineral stacks up to 150 microns in size. Polished shale sections are examined to determine the size, shape orientation, textural relationships, and internal compositional variations of the clays. Preliminary evidence that the clay stacks are authigenic, and may have formed at shallow burial depths during early diagenesis, is presented.

  17. Kisameet Clay Exhibits Potent Antibacterial Activity against the ESKAPE Pathogens

    PubMed Central

    Behroozian, Shekooh; Svensson, Sarah L.

    2016-01-01

    ABSTRACT The ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) pathogens cause an increasing number of nosocomial infections worldwide since they escape the inhibitory effect of the available antibiotics and the immune response. Here, we report the broad-spectrum and potent antibacterial activity of Kisameet clay, a natural clay mineral from British Columbia, Canada, against a group of multidrug-resistant ESKAPE strains. The results suggest that this natural clay might be developed as a therapeutic option for the treatment of serious infections caused by these important pathogens. PMID:26814180

  18. Using solar dryers to dry clay bricks

    SciTech Connect

    Bernal, J.A.; Wicker, R.B.

    1996-12-31

    Experiments using a small-scale solar dryer have been performed to determine the effect of incorporating solar dryers in the pre-firing stage of clay brick production. A comparison of brick moisture content over time is presented for dry bricks that underwent additional drying either naturally through direct exposure, in convection ovens set at 65.6 C and 104 C, in the solar dryer, or sealed in plastic bags. The ambient temperature and relative humidity were monitored along with the solar dryer temperature. Results indicated the solar dryer removed from one to two percent more moisture than natural drying, but removed less moisture than did the ovens. A similar comparison of wet bricks naturally dried, oven dried, and placed in the solar dryer for periods of five and seven days is also presented. The solar dryer reduced the amount of time required for bricks to be dried to a specified moisture content and increased the amount of moisture removed for a given amount of time.

  19. Maya blue: a clay-organic pigment?

    PubMed

    Van Olphen, H

    1966-11-01

    Maya Blue, a pigment used by the Mayas in Yucatan, is remarkably stable: the color is not destroyed by hot concentrated mineral acids or by heating to about 250 degrees C. The principal constituent is the colorless mineral attapulgite. It is proposed that the pigment is an adsorption complex of attapulgite and natural indigo; a synthetic equivalent may be prepared from attapulgite and either indoxylester or indigo, or by applying the vat-dyeing technique, with reduced indigo.The low dye content of the pigment (less than 0.5 percent) indicates that the dye is absorbed only on the external surfaces of the attapulgite particles and not throughout the channels in their structures. The complex as such is not stable to acids, but the stability displayed by Maya Blue is achieved simply by heating the complex to from 75 degrees to 150 degrees C for several days. An analogous stable pigment can be prepared from sepiolite and indigo. No stable pigments could be prepared from clays with platelike structures or from zeolites. PMID:17778806

  20. Hydraulic conductivity of desiccated geosynthetic clay liners

    SciTech Connect

    Boardman, B.T.; Daniel, D.E.

    1996-03-01

    Large-scale tests were performed to determine the effect of a cycle of wetting and drying on the hydraulic conductivity of several geosynthetic clay liners (GCLs). The GCLs were covered with 0.6 m of pea gravel and permeated with water. After steady seepage had developed, the water was drained away, and the GCL was desiccated by circulating heated air through the overlying gravel. The drying caused severe cracking in the bentonite component of the GCLs. The GCLs were again permeated with water. As the cracked bentonite hydrated and swelled, the hydraulic conductivity slowly decreased from an initially high value. The long-term, steady value of hydraulic conductivity after the wetting and drying cycle was found to be essentially the same as the value for the undesiccated GCL. It is concluded that GCLs possess the ability to self-heal after a cycle of wetting and drying, which is important for applications in which there may be alternate wetting and drying of a hydraulic barrier (e.g. within a landfill final cover).

  1. Microstructural analysis of Iberian expanded clay aggregates.

    PubMed

    Bogas, J Alexandre; Mauricio, António; Pereira, M F C

    2012-10-01

    This article presents a detailed study of the microstructure of Iberian expanded clay lightweight aggregates (LWA). Other than more commonly used mercury porosimetry (MP) and water absorption methods, the experimental study involves optical microscopy, scanning electron microscopy (SEM), and microtomography (μ-CT). Pore connectivity and how it is deployed are shown to some degree, and the pore size spectrum is estimated. LWA are in general characterized by a dense outer shell up to 200 μm thick, encasing an inner cellular structure of 10-100 times bigger pore size. Aggregate pore sizes may span from some hundreds of nanometers up to over 1 mm, though the range of 1-25 μm is more typical. A noteworthy fraction of these pores is closed, and they are mainly up to 1 μm. It is also shown that macropore spatial arrangement is affected by the manufacturing process. A step forward is given to understanding how the outer shell and the inner pore network influence the mechanical and physical LWA properties, particularly the density and water absorption. The joint consideration of μ-CT and SEM seems to be the most appropriate methodology to study LWA microstructure. MP analysis is likely to distort LWA pore spectrum assessment. PMID:23031601

  2. Sedimentation of athermal particles in clay suspensions

    NASA Astrophysics Data System (ADS)

    Clotet, Xavier; Kudrolli, Arshad

    2015-03-01

    We discuss sedimentation of athermal particles in dense clay suspensions which appear liquid-like to glass-like. These studies are motivated by the physics important to a diverse range of problems including remediation of oil sands after the extraction of hydrocarbons, and formation of filter cakes in bore wells. We approach this problem by first considering collective sedimentation of athermal spherical particles in a viscous liquid in quasi-two dimensional and three dimensional containers. We examine the system using optical and x-ray tomography techniques which gives particle level information besides global information on the evolution of the volume fraction. Unlike sediments in the dilute limit - which can be modeled as isolated particles that sediment with a constant velocity and slow down exponentially as they approach the bottom of the container - we find interaction between the particles through the viscous fluids leads to qualitatively differences. We find significant avalanching behavior and cooperative motion as the grains collectively settle, and non-exponential increase in settling time. We discuss the effect of stirring caused by the sedimenting particles on their viscosity and consequently the sedimentation rates as a function of particle concentration. Supported by Petroleum Research Fund Grant PRF # 54045-ND9.

  3. Sorption of tylosin on clay minerals.

    PubMed

    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. PMID:24007614

  4. A Comprehensive Analysis of Organic Contaminant Adsorption by Clays

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Macroscopic studies of nonionic organic contaminant (NOC) sorption by clays have revealed many important clues regarding factors that influence sorption affinity, and enabled the development of structural hypotheses for operative adsorption mechanisms. Integrating this understanding with knowledge g...

  5. Weak Polyelectrolyte-Clay Assemblies: Physical Mechanisms of Biological Response

    NASA Astrophysics Data System (ADS)

    Sukhishvili, Svetlana; Pavlukhina, Svetlana; Zhuk, Iryna

    2014-03-01

    We report on a highly efficient, non-leachable antibacterial coating, consisting of an ultrathin nanocomposite hydrogel capable of hosting, protecting and delivering antibiofilm agents in response to bacterial infection. Constructed using layer-by-layer (LbL) deposition of clay nanoplatelets and a weak polyelectrolyte and loaded with an antimicrobial agent (AmA), the coatings was highly resistant to colonization by Staphylococcus aureus. The high antibiofilm activity of the coating results from a combination of highly localized, bacteria-triggered AmA release and hydrogel swelling, as well as retention of AmA by clay nanoplatelets. We discuss the dependence of rheological and swelling properties of weak polyelectrolyte-clay assemblies on film thickness, clay platelet orientation and environmental pH.

  6. Modeling Coupled Processes in Clay Formations for Radioactive Waste Disposal

    SciTech Connect

    Liu, Hui-Hai; Rutqvist, Jonny; Zheng, Liange; Sonnenthal, Eric; Houseworth, Jim; Birkholzer, Jens

    2010-08-31

    As a result of the termination of the Yucca Mountain Project, the United States Department of Energy (DOE) has started to explore various alternative avenues for the disposition of used nuclear fuel and nuclear waste. The overall scope of the investigation includes temporary storage, transportation issues, permanent disposal, various nuclear fuel types, processing alternatives, and resulting waste streams. Although geologic disposal is not the only alternative, it is still the leading candidate for permanent disposal. The realm of geologic disposal also offers a range of geologic environments that may be considered, among those clay shale formations. Figure 1-1 presents the distribution of clay/shale formations within the USA. Clay rock/shale has been considered as potential host rock for geological disposal of high-level nuclear waste throughout the world, because of its low permeability, low diffusion coefficient, high retention capacity for radionuclides, and capability to self-seal fractures induced by tunnel excavation. For example, Callovo-Oxfordian argillites at the Bure site, France (Fouche et al., 2004), Toarcian argillites at the Tournemire site, France (Patriarche et al., 2004), Opalinus clay at the Mont Terri site, Switzerland (Meier et al., 2000), and Boom clay at Mol site, Belgium (Barnichon et al., 2005) have all been under intensive scientific investigations (at both field and laboratory scales) for understanding a variety of rock properties and their relations with flow and transport processes associated with geological disposal of nuclear waste. Clay/shale formations may be generally classified as indurated and plastic clays (Tsang et al., 2005). The latter (including Boom clay) is a softer material without high cohesion; its deformation is dominantly plastic. For both clay rocks, coupled thermal, hydrological, mechanical and chemical (THMC) processes are expected to have a significant impact on the long-term safety of a clay repository. For

  7. Intercalation of Trichloroethene by Sediment-Associated Clay Minerals

    SciTech Connect

    Matthieu, Donald E.; Brusseau, Mark; Johnson, G. R.; Artiola, J. L.; Bowden, Mark E.; Curry, J. E.

    2013-01-01

    The objective of this research was to examine the potential for intercalation of trichloroethene (TCE) by clay minerals associated with aquifer sediments. Sediment samples were collected from a field site inTucson, AZ. Two widely used Montmorillonite specimen clays were employed as controls. X-ray diffraction, conducted with a controlled-environment chamber, was used to characterize smectite interlayer dspacing for three treatments (bulk air-dry sample, sample mixed with synthetic groundwater, sample mixed with TCE-saturated synthetic groundwater). The results show that the d-spacing measured for the samples treated with TCE-saturated synthetic groundwater are larger (*26%) than those of the untreated samples for all field samples as well as the specimen clays. These results indicate that TCE was intercalated by the clay minerals, which may have contributed to the extensive elution tailing observed in prior miscible-displacement experiments conducted with this sediment.

  8. SLIDE PRESENTATION: LIMITATIONS OF USE OF GEOSYNTHETIC CLAY LINERS (GCLS)

    EPA Science Inventory

    This presentation describes the design and construction issues pertaining to the use of geosynthetic clay liners (GCLSs) in waste containment. The presentation covers new materials, potential design and construction pitfalls and a summary of ongoing research.

  9. Clay mineralogy of weathering profiles from the Carolina Piedmont.

    USGS Publications Warehouse

    Loferski, P.J.

    1981-01-01

    Saprolite profiles (12) that formed over various crystalline rocks from the Charlotte 1o X 2o quadrangle showed overall similarity in their clay mineralogy to depths of 6 to 45 m indicating control by weathering processes rather than by rock type. Most saprolite contained 10-25% clay, and ranged 3 to 70%. Kaolinite and halloysite composed = or >75% of the clay fraction of most samples. The ratio kaolinite:halloysite ranged widely, from 95% kaolinite to 90% halloysite, independent of depth. Clay-size mica was present in all profiles, and ranged 5-75% over a sericite schist. Mixed-layer mica-smectite and mica-vermiculite were subordinate; discrete smectite and vermiculite were rare. The abundance of halloysite indicates a continuously humid environment since the time of profile formation, because of the rapidity with which halloysite dehydrates irreversibly. -R.S.M.

  10. A simple approach for calculating pile skin friction in clays

    SciTech Connect

    Mirza, U.A.A.

    1995-12-31

    A simple method is presented for calculating static shaft resistance of a pile driven into clay. The method is based on correlations established for North Sea clays between index properties and strengths. Application of the method to half a dozen full scale pile load tests which are part of the API RP2A`s data base and include a wide range of plasticity properties, overconsolidation ratios and strengths, is described. Except for short piles in very stiff to hard clays, the predictions agree very well with the measurements. The correlations presented allows an assessment of residual skin friction and indicate the importance of the liquidity index of the clay in static capacity calculations.

  11. Preparation and characterization of biodegradable PLA/organosilylated clay nanocomposites

    NASA Astrophysics Data System (ADS)

    Olivieri, R.; Di Maio, L.; Scarfato, P.; Incarnato, L.

    2016-05-01

    In this work a new organosilylated clay was successfully synthesized by functionalization of a natural sodium montmorillonite (MMT) by (3-glycidyloxypropyl)trimethoxysilane (GOPTMS). This organosilylated clay was used as nanofiller for preparation, by solvent casting, of poly(lactic acid) nanocomposite systems. Similar systems, containing as nanofiller the commercial Cloisite 30B (i.e. a natural sodium montmorillonite organically modified with alkylammonium salt), were also prepared for comparison. All the obtained nanocomposite films were characterized using several techniques (XRD, permeability and mechanical tensile tests). Obtained results pointed out that nanocomposite system containing the organosilylated clay showed a better intercalation of the polymer chains into the clay layers and a higher improvement of the oxygen barrier properties, when compared to both the neat PLA film and the PLA film loaded with Cloisite 30B.

  12. CALCINED CLAYS AS A LOW EMISSION CEMENT SUBSTITUTE

    EPA Science Inventory

    This study provides a better understanding of clay-cement materials including: (i) their associated energy demand and carbon dioxide emissions of their manufacturing and transport, (ii) their structural performance and properties, and (iii) their emission characteristics affe...

  13. Thermodynamically coupled mass transport processes in a saturated clay

    SciTech Connect

    Carnahan, C.L.

    1984-11-01

    Gradients of temperature, pressure, and fluid composition in saturated clays give rise to coupled transport processes (thermal and chemical osmosis, thermal diffusion, ultrafiltration) in addition to the direct processes (advection and diffusion). One-dimensional transport of water and a solute in a saturated clay subjected to mild gradients of temperature and pressure was simulated numerically. When full coupling was accounted for, volume flux (specific discharge) was controlled by thermal osmosis and chemical osmosis. The two coupled fluxes were oppositely directed, producing a point of stagnation within the clay column. Solute flows were dominated by diffusion, chemical osmosis, and thermal osmosis. Chemical osmosis produced a significant flux of solute directed against the gradient of solute concentration; this effect reduced solute concentrations relative to the case without coupling. Predictions of mass transport in clays at nuclear waste repositories could be significantly in error if coupled transport processes are not accounted for. 14 references, 8 figures, 1 table.

  14. Studies on structural properties of clay magnesium ferrite nano composite

    NASA Astrophysics Data System (ADS)

    Kaur, Manpreet; Singh, Mandeep; Jeet, Kiran; Kaur, Rajdeep

    2015-08-01

    Magnesium ferrite-bentonite clay composite was prepared by sol-gel combustion method employing citric acid as complexing agent and fuel. The effect of clay on the structural properties was studied with X-ray diffraction (XRD), Fourier transform infrared (FT-IR) Spectroscopy, Scanning electron microscopy (SEM), SEM- Energy dispersive Spectroscope (EDS) and BET surface area analyzer. Decrease in particle size and density was observed on addition of bentonite clay. The BET surface area of nano composite containing just 5 percent clay was 74.86 m2/g. Whereas porosity increased from 40.5 per cent for the pure magnesium ferrite to 81.0 percent in the composite showing that nano-composite has potential application as an adsorbent.

  15. Common clay and shale: a look at 2009 activity

    USGS Publications Warehouse

    Virta, R.L.

    2010-01-01

    An overview of clay and shale production, consumption, and prices in 2009 is presented. The industry has seen 15 to 20 percent declines during the past two years, yet producers still expect sales to decline in 2010.

  16. Characterization of low-purity clays for geopolymer binder formulation

    NASA Astrophysics Data System (ADS)

    Mostafa, Nasser Y.; Mohsen, Q.; El-maghraby, A.

    2014-06-01

    The production of geopolymer binders from low-purity clays was investigated. Three low-purity clays were calcined at 750°C for 4 h. The calcined clays were chemically activated by the alkaline solutions of NaOH and Na2SiO3. The compressive strength was measured as a function of curing time at room temperature and 85°C. The results were compared with those of a pure kaolin sample. An amorphous aluminosilicate polymer was formed in all binders at both processing temperatures. The results show that, the mechanical properties depend on the type and amount of active aluminum silicates in the starting clay material, the impurities, and the processing temperature.

  17. Circular stair from Parking Overlook to Clay Tennis Courts, Riverside ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Circular stair from Parking Overlook to Clay Tennis Courts, Riverside Park at 96th Street, looking southwest. - Henry Hudson Parkway, Extending 11.2 miles from West 72nd Street to Bronx-Westchester border, New York County, NY

  18. Composite clay materials for removal of SOx from gas streams

    SciTech Connect

    Pinnavaia, T.J.; Polansky, C.A.; Amarasekera, J.

    1993-07-06

    A method is described for preparing a composite material capable of removing SO[sub x] from a gas stream comprising the steps of: (a) providing a suspension containing a smectite clay in water; (b) dissolving an amount of sodium carbonate in the suspension of the clay; (c) adding a soluble alkaline earth metal salt in stoichiometric amount for reaction with the sodium carbonate to form an alkaline earth metal carbonate precipitate in the suspension with the clay; and (d) drying the suspension to provide the composite material, wherein when the composite material is heated, the SO[sub x], is removed from the gas. A method is described in accordance with claim 3 wherein the alkaline earth metal carbonate and clay are mixed with an iron salt selected from the group consisting of ferric chloride and ferric nitrate. A method is described in accordance with claim 3 wherein the alkaline earth metal is selected from the group consisting of magnesium and calcium.

  19. Studies on structural properties of clay magnesium ferrite nano composite

    SciTech Connect

    Kaur, Manpreet Singh, Mandeep; Jeet, Kiran Kaur, Rajdeep

    2015-08-28

    Magnesium ferrite-bentonite clay composite was prepared by sol-gel combustion method employing citric acid as complexing agent and fuel. The effect of clay on the structural properties was studied with X-ray diffraction (XRD), Fourier transform infrared (FT-IR) Spectroscopy, Scanning electron microscopy (SEM), SEM- Energy dispersive Spectroscope (EDS) and BET surface area analyzer. Decrease in particle size and density was observed on addition of bentonite clay. The BET surface area of nano composite containing just 5 percent clay was 74.86 m{sup 2}/g. Whereas porosity increased from 40.5 per cent for the pure magnesium ferrite to 81.0 percent in the composite showing that nano-composite has potential application as an adsorbent.

  20. INTERCALATION OF TRICHLOROETHENE BY SEDIMENT-ASSOCIATED CLAY MINERALS

    PubMed Central

    Matthieu, D.E.; Brusseau, M.L.; Johnson, G.R.; Artiola, J.L.; Bowden, M.L.; Curry, J.E.

    2012-01-01

    The objective of this research was to examine the potential for intercalation of trichloroethene (TCE) by clay minerals associated with aquifer sediments. Sediment samples were collected from a field site in Tucson, AZ. Two widely used Montmorillonite specimen clays were employed as controls. X-ray diffraction, conducted with a controlled-environment chamber, was used to characterize smectite interlayer d-spacing for three treatments (bulk air-dry sample, sample mixed with synthetic groundwater, sample mixed with TCE-saturated synthetic groundwater). The results show that the d-spacing measured for the samples treated with TCE-saturated synthetic groundwater are larger (~26%) than those of the untreated samples for all field samples as well as the specimen clays. These results indicate that TCE was intercalated by the clay minerals, which may have contributed to the extensive elution tailing observed in prior miscible-displacement experiments conducted with this sediment. PMID:22921434

  1. Ultrasonically assisted single screw extrusion, film blowing and film casting of LLDPE/clay and PA6/clay nanocomposites

    NASA Astrophysics Data System (ADS)

    Niknezhad, Setareh

    The major objective of this study was to investigate the effect of ultrasonic treatment on the dispersion of modified clay particles in LLDPE and PA6 matrices and the final properties of nanocomposites. LLDPE and PA6 are two polymers that are widely used in packaging industry. Blown and cast films were manufactured from the prepared nanocomposites. To achieve one step film processing, an online ultrasonic film casting was developed. Ultrasonic waves caused high-energy mixing and dispersion due to the acoustic cavitation, causing the clay agglomorates to separate into individual platelets in polymer matrix. Ultrasonic waves also broke down the polymer molecular chains reducing viscosity of the melt, facilating dispersion of the clay platelets throughout the matrix. Ultrasound also led to a breakage of the clay platelets reducing the particle size and improving their distribution. Clay particles acted as a heterogenous nucleation agent generating smaller size polymer crystals. In turn, these improved different properties including mechanical properties, oxygen permeability and transparency of films. In LLDPE/clay 20A nanocomposites, the effect of ultrasound was more obvious at higher clay loadings. Exfoliated structure for ultrasonically treated nanocomposites containing 2.5, 5 and 7.5 wt% of clay 20A and highly intercalated structure for ultrasonically treated nanocomposites containing 10 wt% of clay 20A were achieved. However, in blown films, the exfoliated structure transferred to the intercalated structure due to the addition of more shear and thermal degradation of surfactants of the clay particles. While, manufacturing cast films using the new developed online ultrasonic cast film machine revealed the exfoliated structure with ultrasonic treatment till 7.5 wt% of clay loadings. Cast films of nanocomposites containing 5 wt% of clay loadings were also prepared with addition of different compatibilizers. The compatibilizer containing higher amount of grafted

  2. [Kinetics and mechanism of removing Microcystis aeruginosa using clay flocculation].

    PubMed

    Pan, Gang; Zhang, Mingming; Yan, Hai; Zou, Hua; Chen, Hao

    2003-09-01

    Twenty-six natural clays were studied for their kinetics of flocculating and removing algal cells of Microcystis aeruginosa. According to the 8 h equilibrium removal efficiencies and removal rates at a clay-loading of 0.7 g.L-1, all the 26 clays were classified into three categories. Type-I clay, which includes talc, ferric oxide, sepiolite, ferroferric oxide, and kaolinite, has an equilibrium removal efficiency greater than 90%, a t50 (time needed to remove 50% of the algae) of less than 30 min, and a t80 (time needed to remove 80% of the algae) of less than 2.5 h. Type-II clay, which includes argillanceous rocks, attapulgite, rectorite, illite, and argil, etc., has an equilibrium removal efficiency of 50%-80%, a t50 of less than 2.5 h, and a t80 of more than 5 h. Type-III clay consists of 14 minerals, including laterite, zeolite, mica, clinoptilolite, pumice, tripoli, feldspar and quartz, etc. with the removal efficiency less than 50%, and t50 > > 8 h. When the clay loading was decreased to 0.1-0.2 g.L-1, the 8 h equilibrium removal efficiencies for 25 clays declined to below 60%, except for sepiolite, a Type-I clay, which maintained around 90%. After the sepiolite was modified with Fe3+ to increase its surface charge (Zeta potential from -24.0 mV to +0.43 mV at pH 7.4), the initial removal rate was increased remarkably although its 8 h equilibrium removal efficiency was not improved substantially. As a comparison, the 8 h equilibrium removal efficiency of PAC was no greater than 40% at loadings of 0.02-0.2 g.L-1. Following the analysis of the flocculation mechanism it was concluded that the effect of bridging and netting may play a key role in the clay-algae flocculation processes, which may be important for selecting and modifying clays to improve significantly the removal efficiency. PMID:14719252

  3. Heteroaggregation of Silver Nanoparticles with Clay Minerals in Aqueous System

    NASA Astrophysics Data System (ADS)

    Liu, J.; Burrow, E.; Hwang, Y.; Lenhart, J.

    2013-12-01

    Nanoparticles are increasingly being used in industrial processes and consumer products that exploit their beneficial properties and improve our daily lives. Nevertheless, they also attract attention when released into natural environment due to their potential for causing adverse effects. The fate and transport of nanoparticles in aqueous systems have been the focus of intense study. However, their interactions with other natural particles have received only limited attention. Clay minerals are ubiquitous in most aquatic systems and their variably charged surfaces can act as deposition sites that can alter the fate and transport of nanoparticles in natural aqueous environments. In this study, we investigated the homoaggregation of silver nanoparticles with different coating layers and their heteroaggregation behavior with clay minerals (illite, kaolinite, montmorillonite) in neutral pH solutions. Silver nanoparticles with a nominal diameter of 80 nm were synthesized with three different surface coating layers: uncoated, citrate-coated and Tween-coated. Illite (IMt-2), kaolinite (KGa-2), and montmorillonite (SWy-2) were purchased from the Clay Mineral Society (Indiana) and pretreated to obtain monocationic (Na-clay) and dicationic (Ca-clay) suspensions before the experiments. The change in hydrodynamic diameter as a function of time was monitored using dynamic light scattering (DLS) measurements in order to evaluate early stage aggregation as a function of electrolyte concentration in both the homo- and heteroaggregation scenarios. A shift in the critical coagulation concentration (CCC) values to lower electrolyte concentrations was observed in binary systems, compared to single silver nanoparticle and clay systems. The results also suggest more rapid aggregation in binary system during the early aggregation stage when compared to the single-particle systems. The behavior of citrate-coated silver nanoparticles was similar to that of the bare particles, while the

  4. Painting with Clay: A Study of the Masters

    ERIC Educational Resources Information Center

    Skophammer, Karen

    2010-01-01

    Plasticine clay is a bendable material that is easily manipulated by students of all ages. It is a great material to work with because it does not dry out from day to day, so high-school students can work on an extended project. They do not have to worry about the clay drying and cracking, and the entire work of art does not have to be completed…

  5. Chemical reactions of organic compounds on clay surfaces.

    PubMed Central

    Soma, Y; Soma, M

    1989-01-01

    Chemical reactions of organic compounds including pesticides at the interlayer and exterior surfaces of clay minerals and with soil organic matter are reviewed. Representative reactions under moderate conditions possibly occurring in natural soils are described. Attempts have been made to clarify the importance of the chemical nature of molecules, their structures and their functional groups, and the Brönsted or Lewis acidity of clay minerals. PMID:2533556

  6. A Wii-related clay-shoveler's fracture.

    PubMed

    Brown, Christopher N; McKenna, Patrick

    2009-01-01

    A 38-year-old man presented to the accident and emergency department complaining of severe neck pain. This had started immediately after swinging his Wii game console control during a rather vigorous game. An X-ray demonstrated a clay-shoveler's fracture of C7. This had radiological features to suggest an acute injury. This is the first report of a clay-shoveler's fracture strongly suggestive of being related to the use of a Wii console. PMID:19882086

  7. Experimental study of Human Adenoviruses interactions with clays

    NASA Astrophysics Data System (ADS)

    Bellou, Maria; Syngouna, Vasiliki; Paparrodopoulos, Spyros; Vantarakis, Apostolos; Chrysikopoulos, Constantinos

    2014-05-01

    Clays are used to establish low permeability liners in landfills, sewage lagoons, water retention ponds, golf course ponds, and hazardous waste sites. Human adenoviruses (HAdVs) are waterborne viruses which have been used as viral indicators of fecal pollution. The objective of this study was to investigate the survival of HAdV in static and dynamic clay systems. The clays used as a model were crystalline aluminosilicates: kaolinite and bentonite. The adsorption and survival of HAdVs onto these clays were characterized at two different controlled temperatures (4 and 25o C) under static and dynamic batch conditions. Control tubes, in the absence of clay, were used to monitor virus inactivation due to factors other than adsorption to clays (e.g. inactivation or sorption onto the tubes walls). For both static and dynamic batch experiments, samples were collected for a maximum period of seven days. This seven day time - period was determined to be sufficient for the virus-clay systems to reach equilibrium. To infer the presence of infectious HAdV particles, all samples were treated with Dnase and the extraction of viral nucleid acid was performed using a commercial viral RNA kit. All samples were analyzed by Real - Time PCR which was used to quantify viral particles in clays. Samples were also tested for virus infectivity by A549 cell cultures. Exposure time intervals in the range of seven days (0.50-144 hours) resulted in a load reduction of 0.74 to 2.96 logs for kaolinite and a reduction of 0.89 to 2.92 for bentonite. Furthermore, virus survival was higher onto bentonite than kaolinite (p

  8. An atypical clay shoveler's fracture: a case report

    PubMed Central

    Feldman, Victor B; Astri, Frank

    2001-01-01

    A case of an atypical clay shoveler's fracture with involvement of the spinolaminar line is described. Causative mechanisms of injury, radiographic appearances, differential diagnosis, treatment and prognosis are reviewed. Classic clay shoveler's fractures are considered stable fractures. However, when the spinolaminar line is disrupted, spinal cord involvement must be ruled out. ImagesFigure 1Figure 2Figure 3Figure 4aFigure 4bFigure 5Figure 6

  9. New polyelectrolyte complex from pectin/chitosan and montmorillonite clay.

    PubMed

    da Costa, Marcia Parente Melo; de Mello Ferreira, Ivana Lourenço; de Macedo Cruz, Mauricio Tavares

    2016-08-01

    A new nanocomposite hydrogel was prepared by forming a crosslinked hybrid polymer network based on chitosan and pectin in the presence of montmorillonite clay. The influence of clay concentration (0.5 and 2% wt) as well as polymer ratios (1:1, 1:2 and 2:1) was investigated carefully. The samples were characterized by different techniques: transmission and scanning electron microscopy, X-ray diffraction, thermogravimetric analysis, infrared spectroscopy, swelling degree and compression test. Most samples presented swelling degree above 1000%, which permits characterizing them as superabsorbent material. Images obtained by transmission electron microscopy showed the presence of clay nanoparticles into hydrogel. The hydrogels' morphological properties were evaluated by scanning electron microscope in high and low-vacuum. The micrographs showed that the samples presented porous. The incorporation of clay produced hydrogels with differentiated morphology. Thermogravimetric analysis results revealed that the incorporation of clay in the samples provided greater thermal stability to the hydrogels. The compression resistance also increased with addition of clay. PMID:27112858

  10. The composition and origin of Ghana medicine clays

    PubMed Central

    van Dongen, Bart E.; Fraser, Sharon E.; Insoll, Timothy

    2011-01-01

    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. PMID:21810043

  11. Bacterial diversity in a deep-subsurface clay environment.

    PubMed Central

    Boivin-Jahns, V; Ruimy, R; Bianchi, A; Daumas, S; Christen, R

    1996-01-01

    The presence of bacteria in a deep clay sediment was analyzed in a 20-m-long core horizontally drilled from a mine gallery at a depth of 224 m in the Boom clay formation (Mol, Belgium). This clay deposit is the result of a marine sedimentary process that occurred 35 million years ago. Bacterial activities were estimated by measuring respiration on [14C]glucose. Using the same samples, universal primers for the genes coding for eubacterial 16S rRNA were used to amplify extracted DNA. PCR products were then cloned, sequenced, and analyzed by molecular phylogeny. Our data showed a decrease in bacterial densities as a function of distance from the gallery, with few bacteria detectable by culture at more than 80 cm from the gallery wall. PCR experiments showed the presence of bacteria in all samples, and phylogenetic analyses were then used to tentatively identify these organisms. Because of low bacterial densities in deep clay samples, direct counts and enumeration of viable bacteria on diverse culture media remained negative. All experiments, both cultures and PCR, demonstrated the difficulty of analyzing samples that contain only a few poorly active bacteria as it is difficult to avoid a small contamination by active bacteria during sampling. Since the porosity of the Boom clay formation is less than the expected size of bacteria, it is possible that some of the bacteria present in this 35-million-year-old deep clay deposit derive from cells initially trapped during the sedimentation process. PMID:8795233

  12. Cyclic voltammetry of aquocobalamin on clay-modified electrodes

    SciTech Connect

    Borek, V.; Morra, M.J.

    1998-07-15

    Halogenated synthetic compounds are widespread contaminants of the environment. Although corrinoids reductively dehalogenate synthetic contaminants in solution, the redox behavior of sorbed tetrapyrroles has received limited attention. Colloidal clay suspensions were prepared as Ca{sup 2+} forms of hectorite (SHCa-1), montmorillonite (SWy-1, Syn-1, and SAz-1), and vermiculite (VTx-1) and spin coated on platinum electrodes. Cyclic voltammetry was performed with the clay-modified electrodes immersed in buffered solutions containing 1.0 mM aquocobalamin. Aquocobalamin in the presence of vermiculite-coated electrodes displayed the same cathodic and anodic peak potentials as unmodified electrodes immersed in aquocobalamin solutions. All other clay-modified electrodes shifted cathodic peaks to more negative values, while anodic peak shifts varied with the clay. Hectorite caused the largest shift in formal redox potential as compared to aquocobalamin in solution. The redox behavior of aquocobalamin as modified by sorption to clay minerals potentially affects dehalogenation rates of synthetic organic compounds in the environment. Clays lowering the formal redox potential of the tetrapyrrole create a potentially more efficient catalyst for pollutant degradation. However, thermodynamic data as obtained using cyclic voltammetry cannot be used to make definitive predictions about the kinetics of contaminant dehalogenation. Reductive dehalogenation will be a function of altered electrochemical properties of the tetrapyrrole as well as rates of contaminant diffusion to the site of tetrapyrrole sorption.

  13. Fluoride content of clay minerals and argillaceous earth materials

    USGS Publications Warehouse

    Thomas, J., Jr.; Glass, H.D.; White, W.A.; Trandel, R.M.

    1977-01-01

    A reliable method, utilizing a fluoride ion-selective electrode, is described for the determination of fluoride in clays and shales. Interference by aluminum and iron is minimal. The reproducibility of the method is about ??5% at different levels of fluoride concentration. Data are presented for various clay minerals and for the <2-??m fractions of marine and nonmarine clays and shales. Fluoride values range from 44 ppm (0.0044%) for nontronite from Colfax, WA, to 51,800 ppm (5.18%) for hectorite from Hector, CA. In general, clays formed under hydrothermal conditions are relatively high in fluoride content, provided the hydrothermal waters are high in fluoride content. Besides hectorite, dickite from Ouray, CO, was found to contain more than 50 times as much fluoride (6700 ppm) as highly crystalline geode kaolinite (125 ppm). The clay stratum immediately overlying a fluorite mineralized zone in southern Illinois was found to have a higher fluoride content than the same stratum in a nonmineralized zone approximately 1 mile away. Nonmarine shales in contact with Australian coals were found to be lower in fluoride content than were marine shales in contact with Illinois coals. It is believed that, in certain instances, peak shifts on DTA curves of similar clay minerals are the result of significant differences in their fluoride content. ?? 1977.

  14. Adsorption of diethyl phthalate ester to clay minerals.

    PubMed

    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. PMID:25150972

  15. Partitioning of Laponite Clay Platelets in Pickering Emulsion Polymerization.

    PubMed

    Brunier, Barthélémy; Sheibat-Othman, Nida; Chevalier, Yves; Bourgeat-Lami, Elodie

    2016-01-12

    Partitioning of laponite disklike clay platelets between polymer particles and bulk aqueous phase was investigated in Pickering surfactant-free emulsion polymerization of styrene. Adsorption of laponite clay platelets plays an important role in the stabilization of this system, influencing the particle size and the number of particles, and, hence, the reaction rate. Adsorption isotherms show that, while the laponite clay platelets are almost fully exfoliated in water, they form multilayers on the surface of the polymer particles by the end of polymerization, as confirmed by transmission electron microscopy (TEM). This observation is supported by quartz crystal microbalance, conductivity, and TEM measurements, which reveal interactions between the clay and polystyrene, as a function of the ionic strength. The strong adsorption of clay platelets leaves a low residual concentration in the aqueous phase that cannot cause further nucleation of polymer particles, as demonstrated during seeded emulsion polymerization experiments in the presence of a high excess of clay. A Brunauer-Emmett-Teller (BET)-type model for laponite adsorption on polystyrene particles matches the adsorption isotherms. PMID:26653971

  16. Clay-oil droplet suspensions in electric fields

    NASA Astrophysics Data System (ADS)

    Rozynek, Zbigniew; Fossum, Jon Otto; Kjerstad, Knut; Mikkelsen, Alexander; Castberg, Rene

    2012-02-01

    Silicone oil droplets containing synthetic smectite clay submerged in immiscible organic oil have been studied by observing clay particle movement and oil circulation when an electric field is applied. Results show how electric field strength, dielectric and electrorheological properties as well as electrohydrodynamics determine the fluid flow and clay particle formation. In a presence of the DC electric fields the clay particles formed a ribbon-like structure onto the inner surface of the droplet. The structure consists of short chain-like clay elements orienting parallel to the electric field direction. It is suggested that a combination of two phenomena, namely the induced viscous flow (electrohydrodynamic effect) and the polarization of the clay particles (dielectric effect), contribute to the ribbon-like structure formation. -/abstract- References [1] G. Taylor, Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences 291 (1966) 159--166. [2] J. R. Melcher and G. I. Taylor, Annual Review of Fluid Mechanics 1 (1969) 111--146. [3] H. Sato, N. Kaji, T. Mochizuki, and Y. H. Mori, Physics of Fluids 18 (2006) 127101. [4] D. A. Saville, Annual Review of Fluid Mechanics 29 (1997) 27--64. [5] J. O. Fossum, Y. M'eheust, K. P. S. Parmar, K. D. Knudsen, K. J. Måløy, and D. M. Fonseca Europhysics Letters 74

  17. Porous networks derived from synthetic polymer-clay complexes

    SciTech Connect

    Carrado, K.A.; Thiyagarajan, P.; Elder, D.L.

    1995-05-12

    Synthetic hectorites were hydrothermally crystallized with direct incorporation of a cationic polymer poly(dimethyl diallyl ammonium chloride) (PDDA), and two neutral cellulosic polymers hydroxypropyl methylcellulose (HPMC) and hydroxyethyl cellulose (HEC). Synthetic PDDA-hectorite displays the lowest d-spacing at 15.8 {Angstrom} along with less polymer incorporation (7.8 wt % organic) than the neutral polymers (18--22 wt % organic). Thermal analysis and small angle neutron scattering were used to further examine the polymer-clay systems. Clay platelets of the largest size and best stacking order occur when cationic PDDA polymer is used. PDDA also enhances these properties over the crystallites prepared for a control mineral, where no polymer is used. HEC acts to aggregate the silica, leaving less to react to form clay. The clay platelets which result from HEC are small, not stacked to a large degree, and oriented randomly. Neutral HPMC acts more like cationic PDDA in that larger clay platelets are allowed to form. The extended microstructure of the clay network remains undisturbed after polymer is removed by calcination. When no polymer is used, the synthetic hectorite has a N{sub 2} BET surface area of 200 M{sup 2}/gm, even after calcination. This increases by 20--50% for the synthetic polymer-hectorites after the polymer is removed by calcination.

  18. The composition and origin of Ghana medicine clays.

    PubMed

    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. PMID:21810043

  19. Biodegradation of crude oil saturated fraction supported on clays.

    PubMed

    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. PMID:23670057

  20. Role of interlayer hydration in lincomycin sorption by smectite clays.

    PubMed

    Wang, Cuiping; Ding, Yunjie; Teppen, Brian J; Boyd, Stephen A; Song, Cunyi; Li, Hui

    2009-08-15

    Lincomycin, an antibiotic widely administered as a veterinary medicine, is frequently detected in water. Little is known about the soil-water distribution of lincomycin despite the fact that this is a major determinant of its environmental fate and potential for exposure. Cation exchange was found to be the primary mechanism responsible for lincomycin sorption by soil clay minerals. This was evidenced by pH-dependent sorption, and competition with inorganic cations for sorptive sites. As solution pH increased, lincomycin sorption decreased. The extent of reduction was consistent with the decrease in cationic lincomycin species in solution. The presence of Ca2+ in solution diminished lincomycin sorption. Clay interlayer hydration status strongly influenced lincomycin adsorption. Smectites with the charge deficit from isomorphic substitution in tetrahedral layers (i.e., saponite) manifest a less hydrated interlayer environment resulting in greater sorption than that by octahedrally substituted clays (i.e., montmorillonite). Strongly hydrated exchangeable cations resulted in a more hydrated clay interlayer environment reducing sorption in the order of Ca- < K- < Cs-smectite. X-ray diffraction revealed that lincomycin was intercalated in smectite clay interlayers. Sorption capacity was limited by clay surface area rather than by cation exchange capacity. Smectite interlayer hydration was shown to be a major, yet previously unrecognized, factor influencing the cation exchange process of lincomycin on aluminosilicate mineral surfaces. PMID:19746709

  1. Characterization of clay scales forming in Philippine geothermal wells

    SciTech Connect

    Reyes, A.G. ); Cardile, C.M. )

    1989-01-01

    Smectite scales occur in 24 out of the 36 blocked wells located in Tongonan, Palinpinon and Bacon-Manito. These comprise 2-85% of the well scales and form at depths of 33-2620 m, where measured and fluid inclusion temperatures are 40-320{sup 0}C. Most, however, occur below the production casing show where temperatures are {ge}230{sup 0}C, often at depths coinciding with aquifers. The clay scales are compositionally and structurally different from the bentonite used in drilling, which is essentially sodium-rich montmorillonite. The clay deposits are expanding, generally disordered, and combine the characteristics of a montmorillonite, saponite and vermiculite in terms of reaction to cationic exchange treatments, structure and composition. Six types of clay scales are identified, but the predominant one, comprising 60-100% of the clay deposits in a well, is Mg- and Fe-rich and referred to as a vermiculitic species. The crystallinity, degree of disorder, textures, optical characteristics, structure and relative amounts of structural Al, Mg and Fe vary with time, temperature and fluid composition, but not with depth and measured pressure. Despite its variance from bentonite characteristics, one of the dominant suggested mechanisms of clay scale formation uses the drilling mud in the well as a substrate, from which the Mg- and Fe-rich clay evolves.

  2. Enhanced sorption of trichloroethene by smectite clay exchanged with Cs+.

    PubMed

    Aggarwal, Vaneet; Li, Hui; Boyd, Stephen A; Teppen, Brian J

    2006-02-01

    Trichloroethene (TCE) is one of the most common pollutants in groundwater, and Cs+ can be a cocontaminant at nuclear facilities. Smectite clays have large surface areas, are common in soils, have high affinities for some organic contaminants, and hence can potentially influence the transport of organic pollutants entering soils and sediments. The exchangeable cations present near smectite clay surfaces can radically influence the sorption of organic pollutants by soil clays. This research was undertaken to determine the effect of Cs+, and other common interlayer cations, such as K+ and Ca2+, on the sorption of TCE by a reference smectite clay saponite. Cs-saturated clay sorbed the most TCE, up to 3500 mg/kg, while Ca-saturated smectite sorbed the least. We hypothesize that the stronger sorption of TCE by the Cs-smectite can be attributed to the lower hydration energy and hence smaller hydrated radius of Cs+, which expands the lateral clay surface domains available for sorption. Also, Cs-smectite interlayers are only one or two water layers thick, which may drive capillary condensation of TCE. Our results implicate enhanced retention of TCE in aquifer materials containing smectites accompanied by Cs+ cocontamination. PMID:16509334

  3. Controlling harmful algae blooms using aluminum-modified clay.

    PubMed

    Liu, Yang; Cao, Xihua; Yu, Zhiming; Song, Xiuxian; Qiu, Lixia

    2016-02-15

    The performances of aluminum chloride modified clay (AC-MC), aluminum sulfate modified clay (AS-MC) and polyaluminum chloride modified clay (PAC-MC) in the removal of Aureococcus anophagefferens were compared, and the potential mechanisms were analyzed according to the dispersion medium, suspension pH and clay surface charges. The results showed that AC-MC and AS-MC had better efficiencies in removing A.anophagefferens than PAC-MC. The removal mechanisms of the three modified clays varied. At optimal coagulation conditions, the hydrolysates of AC and AS were mainly monomers, and they transformed into Al(OH)3(am) upon their addition to algae culture, with the primary mechanism being sweep flocculation. The PAC mainly hydrolyzed to the polyaluminum compounds, which remained stable when added to the algae culture, and the flocculation mainly occurred through polyaluminum compounds. The suspension pH significantly influenced the aluminum hydrolysate and affected the flocculation between the modified clay and algae cells. PMID:26763322

  4. Hollow clay tile wall program summary report

    SciTech Connect

    Henderson, R.C.; Jones, W.D.

    1995-07-30

    Many of the Y-12 Plant buildings, constructed during the 1940s and 1950s, consist of steel ed concrete framing infilled with hollow clay tile (HCT). The infill was intended to provide for building enclosure and was not designed to have vertical or lateral load-carrying capacity. During the late 1970s and early 1980s, seismic and wind evaluations were performed on many of these buildings in conjunction with the preparation of a site-wide safety analysis report. This analytical work, based on the best available methodology, considered lateral load-carrying capacity of the HCT infill on the basis of building code allowable shear values. In parallel with the analysis effort, DOE initiated a program to develop natural phenomena capacity and performance criteria for existing buildings, but these criteria did not specify guidelines for determining the lateral force capacity of frames infilled with HCT. The evaluation of infills was, therefore, based on the provisions for the design of unreinforced masonry as outlined in standard masonry codes. When the results of the seismic and wind evaluations were compared with the new criteria, the projected building capacities fell short of the requirements. Apparently, if the buildings were to meet the new criteria, many millions of dollars would be required for building upgrades. Because the upgrade costs were significant, the assumptions and approaches used in the analyses were reevaluated. Four issues were identified: (1) Once the infilled walls cracked, what capacity (nonlinear response), if any, would the walls have to resist earthquake or wind loads applied in the plane of the infill (in-plane)? (2) Would the infilled walls remain within the steel or reinforced concrete framing when subjected to earthquake or high wind loads applied perpendicular to the infill (out-of-plane)? (3) What was the actual shear capacity of the HCT infill? (4) Was modeling the HCT infill as a shear wall the best approach?

  5. Investigating the Influence of Clay Mineralogy on Stream Bank Erodibility

    NASA Astrophysics Data System (ADS)

    Ambers, R. K.; Stine, M. B.

    2005-12-01

    Soil scientists concerned with erosion of agricultural fields and geotechnical engineers concerned with the mechanical behavior of soils under different conditions have both examined the role of clay mineralogy in controlling soil/sediment properties. Fluvial geomorphologists studying stream channel erosion and stability have focused more on the effects of particle-size distribution, vegetation and rooting. The clay mineralogy of bed and bank sediment has the potential to influence cohesiveness and erodibility, however. The goal of this study is to determine the influence of clay mineralogy on the erodibility of natural stream bank sediment, utilizing techniques drawn from pedology and soil mechanics. Bank samples were collected from eleven sites in small watersheds in central and western Virginia. To obtain sediment containing a range of different clay minerals, watersheds with different types of bedrock were chosen for sampling. Rock types included mafic to felsic metamorphic and igneous rocks, shale, sandstone, and limestone. Where stream bank materials were clearly stratified, different layers were sampled separately. X-ray diffraction of the clay-fraction of the sediment indicates the presence of kaolinite, illite, vermiculite, and mixed-layer clay minerals in various abundances in the different samples. Clay content is 9-46%, as determined by the hydrometer method, and textures range from silty clay and silt loam to clay loam and sandy loam. Organic mater contents range from 1-5% by the loss-on-ignition method. Bulk density of intact sediment samples averages 1.5 g/cc. Liquid limits range from 23-41 with one sample having a value of 65; plasticity indices range from 15-22. While these tests predict that the samples would show a range of mechanical behaviors, the channel morphology at the sampling sites was not strikingly different, all having steep cut banks eroded primarily by scour with no evidence of mass movement and most having a width/depth ratio around

  6. Stiff clay masses: big storages of fossil and renewable energy

    NASA Astrophysics Data System (ADS)

    Spilotro, Giuseppe; Fidelibus, Maria Dolores; Qeraxhiu, Lydra; Argentiero, Ilenia; Pellicani, Roberta

    2016-04-01

    The crystalline structure of the clay and its behaviour at the micro and macro scale have been and are still the object of studies in different fields of earth science: mineralogy, geotechnics, etc. It has been known for several decades that the volumetric equilibrium of a well-defined clay (mono mineralogical or mineralogical melange, with or without the mixing with other fines), depends on the salinity of the interstitial fluid (in terms of concentration of one or more kind of salts) under a stress field. The mechanism is very complex involving many chemical and physical topics, but may be easy to understand: the elementary structures of a two faced crystals are electrically negative charged with the interstitial fluid as the dielectric of a capacitor. Consequently, an electrical field is generated whose intensity depends on the electric charge and the properties of the dielectric. Such electric field can produce mechanical work, enlarging the faces of the capacitor, unless external forces prevent it. If external forces exceed the internal ones, the system behaves as a loaded spring, which stores energy of deformation to give back as soon as the external force weakens. The clay of marine sedimentation incorporates interstitial salt water of composition derived and similar to those of sea water. Such type of interstitial water chemically has high concentration of dissolved ions, mainly Na, which generates in the dielectric spaces a low electrical field, compared with that given in identical situation by low salt concentration in interstitial water. In nature, as well described in geoscience, the turning between the two interstitial water types is very common and driven by ion diffusion processes like, surface fresh water interacting with salt interstitial water of old marine clays. The latter, either by the overburden of younger sedimentary layers, but mainly by very strong capillary forces activated by surface drainage and EVT from sun and dry wind, undergo

  7. Iodide interactions with clay minerals: Batch and diffusion studies

    NASA Astrophysics Data System (ADS)

    Miller, A. W.; Kruichak, J.; Mills, M.; Wang, Y.

    2012-12-01

    Clay minerals are likely candidates to aid in nuclear waste isolation due to their low permeability, favorable swelling properties, and high cation sorption capacities. Iodine-129 is often the major driver of exposure risk from nuclear waste repositories at timescales >10,000 years. Therefore, understanding the geochemical cycling of iodine in clays is critical in developing defensible quantitative descriptions of nuclear waste disposal. Anions are not typically considered to interact with most clays as it is assumed that the fixed negative charge of clays actively repels the dissoloved anion. This is corroborated by many batch studies, but diffusion experiments in compacted clays have shown iodide retardation relative to chloride. The reasons for this are unknown; however, several possible hypotheses include: redox transformation controls on sorption behavior, complex surface charge environments due to overlapping charge domains, and sorption to ancillary minerals or weathering products. Seven different clay minerals have been examined using several techniques to chracterize the surface charge environment and iodide uptake. The use of a series of clays shifts the independent variable away from water chemistry characteristics (pH, contaminant concentration), and toward structural characterisitics of clay minerals including isomorphous substitution and clay texture. Iodide uptake batch experiments were completed with the clay minerals in a range of swamping electrolytes. The results give evidence for a novel uptake mechanism involving ion pair formation and iodide concentration within nano-confined environments. These results were further tested using diffusional columns where nano-confined regimes make up a larger proportion of the total porosity. These columns were compacted to different hydrostatic pressures and saturated with different ionic compositions. Porosity distributions were characterized with a fluoride tracer. Iodide diffusion characteristics were

  8. Heavy metal interactions with phosphatic clay: sorption and desorption behavior.

    PubMed

    Singh, S P; Ma, L Q; Harris, W G

    2001-01-01

    Heavy metals produced and released during agricultural and industrial activities may pose a serious threat to the environment. This study investigated the effectiveness of phosphatic clay, a by-product of the phosphate mining industry, for immobilizing heavy metals (Pb(+2), Cd(+2), and Zn(+2)) from aqueous solutions. A batch equilibrium technique was adopted to evaluate metal sorption in the presence of 0.05 M KNO3 background electrolyte solution. The amounts of metals sorbed onto phosphatic clay decreased in the order Pb(+2) > Cd(+2) > Zn(+2). Desorption data suggest that a large fraction of metals sorbed onto phosphatic clay stayed intact under a wide variation in extracting solution pH (ranging from 3 to 10). Desorption rates were slowest for Pb followed by Cd and Zn. Only 8.1 to 23.1% of Pb, 8.4 to 45% of Cd, and 21.9 to 73.9% of Zn sorbed on phosphatic clay was mobilized by USEPA toxicity characteristic leaching procedure (TCLP) solutions at pH 2.93+/-0.05 and 4.93+/-0.05, respectively. Formation of fluoropyromorphite [Pb10(PO4)6(F2)], confirmed by scanning electron microscopy (SEM) and X-ray diffraction (XRD), after reaction of aqueous Pb with phosphatic clay suggested that precipitation remained the dominant mechanism for Pb removal from aqueous solution. In the case of aqueous Cd and Zn interaction with phosphatic clay, we are not able to confirm the formation of a new amorphous and/or crystalline phase on the basis of available information. Other possible sorption mechanisms for Cd and Zn may include sorption and coprecipitation. Thus, phosphatic clay may be an effective amendment for in situ immobilization of heavy metals in contaminated soils and sediments. PMID:11790002

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

    PubMed

    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. PMID:26456605

  10. In situ interaction between different concretes and Opalinus Clay

    NASA Astrophysics Data System (ADS)

    Jenni, A.; Mäder, U.; Lerouge, C.; Gaboreau, S.; Schwyn, B.

    Interactions between cementitious materials and claystone are driven by chemical gradients in pore water and might lead to mineralogical modifications in both materials. In the context of a radioactive waste repository, this alteration might influence safety-relevant clay properties like swelling pressure, permeability, or specific retention. In this study, interfaces of Opalinus Clay, a potential host-rock in Switzerland, and three concrete formulations emplaced in the Cement-Clay Interaction (CI) Experiment at the Mont Terri Underground Laboratory (St. Ursanne, Switzerland) were analysed after 2.2 years of interaction. Sampling techniques with interface stabilisation followed by inclined intersection drilling were developed. Element distribution maps of the concrete-clay interfaces show complex zonations like sulphur enrichment, zones depleted in Ca but enriched in Mg, strong Mg enrichment adjacent to the interface, or carbonation. Consistently, the carbonated zone shows a reduced porosity. Properties of the complex zonation strongly depend on cement properties like water content and pH (ordinary Portland cement vs. low-pH cement). An increased Ca or Mg content in the first 100 μm next to the interface is observed in Opalinus Clay. The cation occupancy of clay exchanger phases next to the ordinary Portland cement interface is depleted in Mg, but enriched in Na, whereas porosity shows no changes at all. The current data suggests migration of CO2/HCO3-, SO42-, and Mg species from clay into cement. pH decrease in the cement next to the interface leads to instability of ettringite, and the sulphate liberated diffuses towards higher pH regions (away from the interface), where additional ettringite can form.

  11. Surfactant-modified bentonite clays: preparation, characterization, and atrazine removal.

    PubMed

    Dutta, Anirban; Singh, Neera

    2015-03-01

    Bentonite clay was modified using quaternary ammonium cations, viz. phenyltrimethylammonium (PTMA), hexadecyltrimethylammonium (HDTMA), trioctylmethylammonium (TOMA) [100 % of cation exchange capacity of clay], and stearylkonium (SK) [100 % (SK-I) and 250 % (SK-II) of cation exchange capacity of clay]. The organoclays were characterized using X-ray diffraction (XRD), infrared (IR) spectroscopy, and scanning electron microscopy (SEM). Atrazine adsorption on modified clays was studied using a batch method. Bentonite clay was a poor adsorbent of atrazine as 9.4 % adsorption was observed at 1 μg mL(-1) atrazine concentration. Modification of clay by PTMA cation did not improve atrazine adsorption capacity. However, atrazine adsorption in HDTMA-, TOMA-, and SK-bentonites varied between 49 and 72.4 % and data fitted well to the Freundlich adsorption isotherm (R > 0.96). Adsorption of atrazine in organoclays was nonlinear and slope (1/n) values were <1. The product of Freundlich adsorption constants, K f(1/n) in HDTMA-, TOMA-, and SK-I-bentonites was 239.2, 302.4, and 256.6, respectively, while increasing the SK cation loading in the clay (SK-II) decreased atrazine adsorption [K f(1/n) - 196.4]. Desorption of atrazine from organoclays showed hysteresis and TOMA- and SK-I-bentonites were the best organoclays to retain the adsorbed atrazine. Organoclays showed better atrazine removal from wastewater than an aqueous solution. The synthesized organoclays may find application in soil and water decontamination and as a carrier for atrazine-controlled released formulations. PMID:25273519

  12. Lanthanide sorption on smectitic clays in presence of cement leachates

    NASA Astrophysics Data System (ADS)

    Galunin, Evgeny; Alba, María D.; Santos, Maria J.; Abrão, Taufik; Vidal, Miquel

    2010-02-01

    Due to their potential retention capacity, clay minerals have been proposed for use in the engineered barriers for the storage of high-level radioactive actinides in deep geological waste repositories. However, there is still a lack of data on the sorption of actinides in clays in conditions simulating those of the repositories. The present article examines the sorption of two lanthanides (actinide analogues) in a set of smectitic clays (FEBEX bentonite, MX80 bentonite, hectorite, saponite, Otay montmorillonite, and Texas montmorillonite). Distribution coefficients ( Kd) were determined in two media: water and 0.02 mol L -1 Ca, the latter representing the cement leachates that may modify the chemical composition of the water in contact with the clay. The Kd values of the lanthanides used in the experiments (La and Lu) varied greatly (25-50 000 L kg -1) depending on the ionic medium (higher values in water than in the Ca medium), the initial lanthanide concentration (up to three orders of magnitude decrease inversely with lanthanide concentration), and the examined clay (up to one order of magnitude for the same lanthanide and sorption medium). Freundlich and Langmuir isotherms were used to fit sorption data to allow comparison of the sorption parameters among smectites. The model based on the two-site Langmuir isotherms provided the best fit of the sorption data, confirming the existence of sorption sites with different binding energies. The sites with higher sorption affinity were about 6% of the total sorption capacity in the water medium, and up to 17% in the Ca medium, although in this latter site sorption selectivity was lower. The wide range of Kd values obtained regarding the factors examined indicated that the retention properties of the clays should also be considered when selecting a suitable clay for engineered barriers.

  13. Constitutive relationships for elastic deformation of clay rock: Data Analysis

    SciTech Connect

    Liu, H.H.; Rutqvist, J.; Birkholzer, J.T.

    2011-04-15

    Geological repositories have been considered a feasible option worldwide for storing high-level nuclear waste. Clay rock is one of the rock types under consideration for such purposes, because of its favorable features to prevent radionuclide transport from the repository. Coupled hydromechanical processes have an important impact on the performance of a clay repository, and establishing constitutive relationships for modeling such processes are essential. In this study, we propose several constitutive relationships for elastic deformation in indurated clay rocks based on three recently developed concepts. First, when applying Hooke's law in clay rocks, true strain (rock volume change divided by the current rock volume), rather than engineering strain (rock volume change divided by unstressed rock volume), should be used, except when the degree of deformation is very small. In the latter case, the two strains will be practically identical. Second, because of its inherent heterogeneity, clay rock can be divided into two parts, a hard part and a soft part, with the hard part subject to a relatively small degree of deformation compared with the soft part. Third, for swelling rock like clay, effective stress needs to be generalized to include an additional term resulting from the swelling process. To evaluate our theoretical development, we analyze uniaxial test data for core samples of Opalinus clay and laboratory measurements of single fractures within macro-cracked Callovo-Oxfordian argillite samples subject to both confinement and water reduced swelling. The results from this evaluation indicate that our constitutive relationships can adequately represent the data and explain the related observations.

  14. Fluxes of clay minerals in the South China Sea

    NASA Astrophysics Data System (ADS)

    Schroeder, Annette; Wiesner, Martin G.; Liu, Zhifei

    2015-11-01

    In order to assess dominant settling processes that change the composition of the detrital clay fraction during transport from neighboring estuaries to a deep sea basin, we studied relative clay mineral abundances and absolute clay mineral fluxes of clay-sized sinking particulate matter collected by eight sediment trap systems deployed from shallow to deep water depth in the South China Sea. This is the first basin-wide study on recent sedimentation processes in the western Pacific marginal seas. Annual averages of relative clay mineral abundances at the shallow traps are temporally more variable and regionally more diverse, resembling those of surrounding drainage basins. In contrast, higher fluxes of material reach the deeper traps. Their characteristics trend temporally and spatially towards uniformity and are enriched with smectite in the entire deep basin. Sinking particulate matter that reaches the shallow traps spends less time in pelagic transport and is affected by monsoonal current reversals. The enrichment in smectite in the deeper traps is a result of longer duration in transport at low velocities, which may increase the effect of differential settling during transport. The trend is caused by lateral advection driven by the cyclonic deep circulation, and this is considered as the main transport process in the northern and central deep basin. The high fluxes in the south-western deep basin could be the result of laterally advected re-suspended sediments from the neighboring shelves. The effects on the composition of the detrital clay fraction caused by oceanographic control, which indirectly include those by differential settling, mask the climatic signal from surrounding drainage basins in the deep basin sediments. This strongly affects the interpretation of the clay mineralogical record in sediments deposited under recent conditions in the South China Sea deep basin.

  15. Encapsulation of clay by ad-miniemulsion polymerization: the influence of clay size and modifier reactivity on latex morphology and physical properties.

    PubMed

    Zengeni, Eddson; Hartmann, Patrice C; Pasch, Harald

    2012-12-01

    The influence of clay platelet size and type of organic modifier (reactive or nonreactive) on highly filled hybrid latex morphology and physical properties of the resultant polymer/clay nanocomposites (PCNs) were investigated. The hybrid latexes, containing clay loadings between 30 and 50 wt % clay, were prepared using ad-miniemulsion polymerization. These materials have potential use in the packaging and coating industry since clay platelets are well-known for barrier property improvements. Comparative studies on the use of montmorillonite (MMT), a large clay platelet (average size: 50-500 nm), and Laponite (Lap), small-sized clay platelets (average size: 25-40 nm), were conducted. Two different clay modifiers were used to modify the clays, i.e., a conventional nonreactive modifier (cetyltrimethylammonium bromide (CTAB)) and a reactive modifier (vinylbenzyldodecyldimethylammonium chloride (VBDAC)). Transmission electron microscopy (TEM) imaging of the hybrid latexes clearly showed strong morphological dependency on both the type of modifier and the clay platelet size. Furthermore, TEM together with small-angle X-ray scattering (SAXS) showed that the extent of clay exfoliation was strongly dependent on the reactivity of the clay modifier, irrespective of the clay platelet size. Both the type of modifier and clay platelets size were found to have an influence on different physical properties of the resultant PCNs. The influence of clay size was clearly indicated by storage modulus and thermal stability behaviors, while that of the clay modifier was indicated by the T(g). Lap-based PCNs exhibited constant or increasing storage modulus and no change in thermal stability with increasing clay content, while MMT-based PCNs showed a decreasing trend in both storage modulus and thermal stability. PCNs based on clay modified with CTAB showed a decreasing T(g) with increasing clay content, while those based on clay modified with VBDAC showed an increasing trend. It was

  16. Polyimide-Clay Composite Materials for Space Application

    NASA Technical Reports Server (NTRS)

    Orwoll, Robert A.; Connell, John W. (Technical Monitor)

    2005-01-01

    The introduction of nanometer-sized clay particles into a polyimide matrix has been shown to enhance the physical properties of specific polymer systems. The clay comprises large stacked platelets of the oxides of aluminum and silicon. These sheets have long dimensions on the order of tenths of a micrometer and thicknesses of several nanometers. Homogeneous dispersion of the clay platelets in the polymer matrix is necessary to achieve those enhancements in polymer properties. Natural montmorillonite with the empirical formula Na0.33Mg0.33Al1.67(OH)2(Si4O10) contains exchangeable inorganic cations. The clay lamellae stack together with the positive sodium ions situated between the surfaces of the individual sheets to balance negatively charged oxygen atoms that are on the surfaces of the sheets. These surface charges contribute to strong electrostatic forces which hold the sheets together tightly. Exfoliation can be accomplished only with unusual measures. In preparing clay nanocomposites, we have taken two steps to try to reduce these interlamellar forces in order to promote the separation (exfoliation) of the sheets and the dispersion of the individual clay particles throughout the organic polymer matrix. In the first step, some of the surface Na(+) ions are replaced with Li(+) ions. Unlike sodium cations, the lithium cations migrate into the interior of the lamellae when the system is heated. Their departure from the surface reduces the surface charge and therefore the attractive forces between the sheets. The loss of alkali metal cations from the surface can be measured as the cation exchange capacity (CEC) of the clay. For example, we found that the CEC of montmorillonite clay was reduced by almost two thirds by treating it with lithium ions and heating to 250 C for 24 hr. Lesser heating has a smaller effect on the CEC. X-ray diffraction measurements show that the d-spacing decreased from ca. 1.34 to 0.97 nm, apparently a consequence of a collapse of the clay

  17. Microbial Impacts on Clay Mineral Transformation and Reactivity

    NASA Astrophysics Data System (ADS)

    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

  18. Formation of stable nanocomposite clays from small peptides reacted with montmorillonite and illite-smectite mixed layer clays

    NASA Astrophysics Data System (ADS)

    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

  19. Immersion Freezing of Clay Minerals and its Time Dependence

    NASA Astrophysics Data System (ADS)

    Hiranuma, N.; Moehler, O.; Bundke, U.; Cziczo, D. J.; Danielczok, A.; Ebert, M.; Garimella, S.; Hoffmann, N.; Kanji, Z. A.; Kiselev, A. A.; Raddatz, M.; Stetzer, O.

    2012-12-01

    Immersion ice nucleation efficiency of clay minerals has been investigated using the AIDA (Aerosol Interaction and Dynamics in the Atmosphere) cloud chamber. Various clay dust samples, including two illite as well as three kaolinite standards, have been examined in the temperature range between 238 K and 255 K. We observed two trends in immersion ice nucleation properties as cloud expansion conditions in the AIDA are varied. First, as previously described in the literature, the supersaturation required for the immersion freezing of clay minerals decreased with decreasing temperature and increasing inferred ice-active surface site densities. Second, the ice nucleation activity of clay minerals strongly depended on the solo-parameter, which is the rate change in temperature (i.e., dNice/dT = ∂Nice/∂t ÷ ∂T/∂t). Further time dependence of ice formation is investigated and discussed as a function of cooling rates, ice nuclei (IN), and aerosol concentrations. Ice residuals collected through a pumped counterflow virtual impactor are examined by electron microprobe analyses to seek the true chemical and physical identity of IN in clay minerals. Brief comparisons of AIDA measurement to the measurements with other ice nucleation chambers (e.g., ETH-PINC, FINCH, and commercially available DMT-SPIN) are also presented.

  20. Effect of sonication on the particle size of montmorillonite clays.

    PubMed

    Poli, Alessandra L; Batista, Tatiana; Schmitt, Carla C; Gessner, Fergus; Neumann, Miguel G

    2008-09-15

    This paper reports on the effect of sonication on SAz-1 and SWy-1 montmorillonite suspensions. Changes in the size of the particles of these materials and modifications of their properties have been investigated. The variation of the particle size has been analyzed by DLS (dynamic light scattering). In all cases the clay particles show a bimodal distribution. Sonication resulted in a decrease of the larger modal diameter, as well as a reduction of its volume percentage. Simultaneously, the proportion of the smallest particles increases. After 60 min of sonication, SAz-1 presented a very broad particle size distribution with a modal diameter of 283 nm. On the other hand, the SWy-1 sonicated for 60 min presents a bimodal distribution of particles at 140 and 454 nm. Changes in the properties of the clay suspensions due to sonication were evaluated spectroscopically from dye-clay interactions, using Methylene Blue. The acidic sites present in the interlamellar region, which are responsible for dye protonation, disappeared after sonication of the clay. The changes in the size of the scattering particles and the lack of acidic sites after sonication suggest that sonication induces delamination of the clay particles. PMID:18572177

  1. Modification of clay-based waste containment materials

    SciTech Connect

    Adu-Wusu, K.; Whang, J.M.; McDevitt, M.F.

    1997-12-31

    Bentonite clays are used extensively for waste containment barriers to help impede the flow of water in the subsurface because of their low permeability characteristics. However, they do little to prevent diffusion of contaminants, which is the major transport mechanism at low water flows. A more effective way of minimizing contaminant migration in the subsurface is to modify the bentonite clay with highly sorptive materials. Batch sorption studies were conducted to evaluate the sorptive capabilities of organo-clays and humic- and iron-based materials. These materials proved to be effective sorbents for the organic contaminants 1,2,4-trichlorobenzene, nitrobenzene, and aniline in water, humic acid, and methanol solution media. The sorption capacities were several orders of magnitude greater than that of unmodified bentonite clay. Modeling results indicate that with small amounts of these materials used as additives in clay barriers, contaminant flux through walls could be kept very small for 100 years or more. The cost of such levels of additives can be small compared to overall construction costs.

  2. Adsorption and Desorption of Nitrogen and Water Vapor by clay

    NASA Astrophysics Data System (ADS)

    Cui, Deshan; Chen, Qiong; Xiang, Wei; Huang, Wei

    2015-04-01

    Adsorption and desorption of nitrogen and water vapor by clay has a significant impact on unsaturated soil physical and mechanical properties. In order to study the adsorption and desorption characteristics of nitrogen and water vapor by montmorillonite, kaolin and sliding zone soils, the Autosorb-iQ specific surface area and pore size analyzer instrument of United State was taken to carry out the analysis test. The adsorption and desorption of nitrogen at 77K and water vapor at 293K on clay sample were conducted. The theories of BET, FHH and hydration energy were taken to calculate the specific surface, surface fractal dimension and adsorption energy. The results show that the calculated specific surface of water vapor by clay is bigger than nitrogen adsorption test because clay can adsorb more water vapor molecule than nitrogen. Smaller and polar water vapor molecule can access the micropore and then adsorb on the mineral surface and mineral intralayer, which make the mineral surface cations hydrate and the mineral surface smoother. Bigger and nonpolar nitrogen molecule can not enter into the micropore as water vapor molecule and has weak interaction with clay surface.

  3. Processes and controls in swelling anhydritic clay rocks

    NASA Astrophysics Data System (ADS)

    Mutschler, Thomas; Blum, Philipp; Butscher, Christoph

    2015-04-01

    Referring to the swelling of anhydritic clay rocks in tunneling, Leopold Müller-Salzburg noted in the third volume on tunneling of his fundamental text book on rock engineering that "a truly coherent explanation of these phenomena is still owing" (Müller-Salzburg 1978, p. 306). This valuation is still true after more than three decades of research in the field of swelling anhydritic clay rocks. One of the reasons is our limited knowledge of the processes involved in the swelling of such rocks, and of the geological, mineralogical, hydraulic, chemical and mechanical controls of the swelling. In this contribution, a review of processes in swelling anhydritic clay rocks and of associated controls is presented. Also numerical models that aim at simulating the swelling processes and controls are included in this review, and some of the remaining open questions are pointed out. By focusing on process-oriented work in this review, the presentation intends to stimulate further research across disciplines in the field of swelling anhydritic clay rocks to finally get a step further in managing the swelling problem in geotechnical engineering projects. Keywords: swelling; anhydritic clay rocks; review

  4. Preparation and Properties of Clay/SEBS Intercalated Composites

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Tomohiro; Yamada, Eisuke

    Clay/polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene triblock copolymer (SEBS) intercalated composites were prepared by melt-blending. The clays were a pristine montmorillonite (Mt) and three organically modified montmorillonites (organo-Mts) with different amounts of distearyldimethylammonium (D18) cation. The amounts of D18 were 50, 70 and 100% of the cation exchange capacity (denoted as D18Mt(50), D18Mt(70) and D18Mt(100), respectively). The clay/SEBS composites were characterized by field-emission scanning electron microscopy (FE-SEM), X-ray diffraction analysis (XRD). The dynamic mechanical analysis (DMA) and the tensile properties were also examined. The size of agglomerated clay particles decreased with the increasing amount of D18. The FE-SEM image of D18Mt(100)/SEBS revealed that the clay particles were dispersed at the sub-μm level (100-500 nm). The XRD patterns suggested that the SEBS chains were inserted into the interlayers of the organo-Mts. The DMA curves indicated that the addition of the organo-Mts produced an increase in the storage modulus in the rubbery plateau region, but a slight decrease in the glass transition temperature of the polystyrene domains. The tensile properties of the organo-Mt/SEBS composites were higher than those of the unmodified Mt/SEBS. D18Mt(100)/SEBS displayed an improved tensile modulus, tear strength and hardness compared to pure SEBS, without sacrificing the tensile strength and elongation at break.

  5. Enhanced photodegradation of organic dyes adsorbed on a clay.

    PubMed

    Tani, Seiji; Yamaki, Hiroshi; Sumiyoshi, Azumi; Suzuki, Yasutaka; Hasegawa, Shinya; Yamazaki, Suzuko; Kawamata, Jun

    2009-01-01

    The interaction of three photoactive organic dyes, Rhodamine B, Rhodamine 6G and a stilbazolium derivative 4'-dimethylamino-N-methyl-4-stilbazolium with synthetic sodium-saponite has been examined by UV-visible absorption spectroscopy. In all cases, bathochromic shifts and the reduction of peak absorbance for the dyes were observed in the absorption spectra at a low dye concentration (25% adsorption of the cation exchange capacity (CEC) of the clay), although the shape and the width of their absorption bands were similar to those in aqueous solution. This absorption behavior indicates that the organic dye molecules adsorbed onto the surface of the negatively charged clay particles and the adsorbed molecules were well dispersed. The photodegradation of the organic dyes in aqueous solution and in the clay suspension has been also examined by the irradiation of a laser beam at a wavelength of 532 nm. We have found that the hybridization of the organic dyes with the exfoliated clay particles largely enhanced a photodegradation. The clay particles acted as a catalyst even at a high concentration such as approximately 300% of CEC. PMID:19441365

  6. Adsorption of cobalt ions from waste water on activated Saudi clays

    NASA Astrophysics Data System (ADS)

    Al-Jlil, Saad A.

    2014-11-01

    The aim of this work was to remove the Cobalt ions from wastewater by three types of Saudi clay. These were collected from Tabbuk city (Tabbuk clay), Khiber city (Khiber clay), and Bahhah city (Bahhah clay). The paper also examined the effect of different activators on the enhancement of adsorption capacity of clays for cobalt ions. The results showed minor enhancement in the adsorption capacities of cobalt ions on three types of clays activated by acid treatment. The adsorption capacity of clays improved particularly for Tabbuk clay when treated with hydrogen peroxide as an activator. The adsorption capacity increased from 3.94 to 12.9 mg/g for the untreated and treated Tabbuk clay, respectively. Also, the adsorption capacity of Bahhah clay increased by activating with sodium chloride from 3.44 to 12.55 mg/g for untreated and treated sample, respectively. The equilibrium adsorption data were correlated using five equilibrium equations, namely, Langmuir, Freundlich, Langmuir-Freundlich, BET, and Toth isotherm equations. Langmuir isotherm agreed well with the experimental data of Khiber and Bahhah clay, while Freundlich model and Langmuir-Freundlich model fitted well with the experimental data of Tabbuk and Bahhah clay activated by NaCl. The results showed that Freundlich model fitted well with the experimental data of Tabbuk clay when activated by H2O2 and H2SO4. Finally, the BET model did not describe the experimental data well for the three types of clay after activation.

  7. Immobilization of radioactive waste by cementation with purified kaolin clay.

    PubMed

    Osmanlioglu, A Erdal

    2002-01-01

    A study is undertaken to determine the waste immobilization performance of low-level wastes in cement-clay mixtures. Liquid low-level wastes are precipitated using chemical methods, followed by solidification in drums. Solidification is done using cementation processes. Long-term leaching rates of the radionuclides are used as indicators of immobilization performance of solidified waste forms. In addition to evaluating the effects of kaolin clay on the leaching properties of the cemented waste forms, the effect of addition of kaolin on the strength of the cemented waste form is also investigated. The long term leaching tests show that inclusion of kaolin in cement reduces the leaching rates of the radionuclides significantly. However, clay additions in excess of 15 wt.% causes a significant decrease in the hydrolytic stability of cemented waste form. It is found that the best waste isolation, without causing a loss in the mechanical strength, is obtained when the kaolin content in cement is 5%. PMID:12092756

  8. Pillared Interlayered Clays as Adsorbents of Gases and Vapors

    NASA Astrophysics Data System (ADS)

    Pires, J.; Pinto, M. L.

    This chapter reviews recent works where porous materials prepared from clays, particularly pillared interlayered clays (PILCs), were studied as gas phase adsorbents. It also includes the cases which used the adsorption of gases and vapors for the nanotextural characterization of the materials, other than the usual low temperature nitrogen adsorption. This is, for instance, the case of the adsorption of molecules of volatile organic compounds (VOCs), with various dimensions and shapes, which can be used as probe molecules for the characterization of the porosity or concerning the topic of the VOCs abatement. A similar situation occurs with water adsorption, whose results can be informative not only on the desiccant properties of the materials but also on their surface chemistry. A more recent line of studies of adsorption by materials prepared from clays, namely, the hydrocarbon purification from natural gas or biogas, was also addressed.

  9. Chemical evolution. XL - Clay-mediated oxidation of diaminomaleonitrile

    NASA Technical Reports Server (NTRS)

    Ferris, J. P.; Hagan, W. J., Jr.; Alwis, K. W.; Mccrea, J.

    1982-01-01

    The inhibition of the oligomerization of HCN by montmorillonite clays is shown to be caused by oxidation of diaminomaleonitrile (DAMN) by ferric ion in the clay lattice, with ferrous ion and oxalic acid the reaction products. It is demonstrated that diiminosuccinonitrile is the initial reaction product and is rapidly hydrolized to oxalic acid and HCN. The same oxidative transformations are effected by ferric ion bound to Dowex 50, ferric ion in solution, and Ni(NH3)6(2+). The rate of reaction of DAMN indicates no catalytic role for the clay in the oxidation of DAMN, and little reaction of the latter was observed with montmorillonite in which the bulk of the iron was in the divalent state. The possible significance of these redox reactions to chemical evolution is discussed.

  10. The Mobility of Organic Contaminants in Water and Clays

    NASA Astrophysics Data System (ADS)

    Lock, P. A.; Skipper, N. T.; Mirza, Z.; Fernandez-Alonso, F.; Adams, M.; Howells, S.; Swenson, J.

    2005-12-01

    The interlayer pores of swelling clays provide an ideal environment in which to study confined fluids, and are the site of many important hydrological and petrological processes. Swelling clays, such as vermiculites, are layered minerals, widespread in soils and sedimentary rocks and are an important sink/source of many toxic organic chemicals. Knowledge of diffusion of organics through clay-rich materials is therefore highly relevant to environmental issues. Experimental studies of solvation structure in aqueous systems show that charged groups can co-ordinate the surrounding water molecules quite strongly, but their is less certainty about the effect of polar and apolar groups. There is currently interest in bulk water-alcohol systems since these are known to aggregate at the nanometer scale. Our hypothesis is that the property of the interlayer fluids in clays arises from the very subtle balance of forces between the interactions of water, cations, clay and organic species. Quasi Elastic Neutron Scattering (QENS) has been used to probe the dynamics of fluids trapped inside clays and reveal the first detailed picture of confined methanol, phenol and glycol in aqueous solution. The picture that emerges is that these model contaminant molecules are surprisingly mobile. Successive QENS broadening for methanol in Na-Vermiculite over 150-330K was measured. The progressive broadening of the energy signal was accompanied by decrease in amplitude with rise in temperature. This is indicative of an overall increase in rotational and translational freedom. Methanol exhibits a Fickian diffusion mechanism as an unconfined fluid, characterised by a linear dependence of broadening of the energy signal with the scattering vector. Inside Na-Vermiculite clay however, the same fluid produces a signal broadening that becomes non-linear indicating a jump activated motion to be present. Glycol and phenol are also of fundamental interest, the former as a clay-swelling inhibitor of

  11. Clay-based polymer nanocomposites: research and commercial development.

    PubMed

    Zeng, Q H; Yu, A B; Lu, G Q; Paul, D R

    2005-10-01

    This paper reviews the recent research and development of clay-based polymer nanocomposites. Clay minerals, due to their unique layered structure, rich intercalation chemistry and availability at low cost, are promising nanoparticle reinforcements for polymers to manufacture low-cost, lightweight and high performance nanocomposites. We introduce briefly the structure, properties and surface modification of clay minerals, followed by the processing and characterization techniques of polymer nanocomposites. The enhanced and novel properties of such nanocomposites are then discussed, including mechanical, thermal, barrier, electrical conductivity, biodegradability among others. In addition, their available commercial and potential applications in automotive, packaging, coating and pigment, electrical materials, and in particular biomedical fields are highlighted. Finally, the challenges for the future are discussed in terms of processing, characterization and the mechanisms governing the behaviour of these advanced materials. PMID:16245517

  12. Synthesis, characterization and properties of fluoroelastomer/clay nanocomposites

    NASA Astrophysics Data System (ADS)

    Lakshminarayanan, Sriram

    The aim of the thesis is to prepare fluoroelastomer/clay nanocomposites by melt-mixing and investigate the effect of nano-dispersion on composite properties. Using theological and morphological analyses, it was found that intercalated FKM nanocomposites can he obtained by using di(hydrogenated tallow-alkyl) dimethyl ammonium modified organoclays. However, the presence of excess amount of modifier did not improve the composite morphology but rather resulted in plasticization of the elastomer matrix. The vulcanization conditions were shown to be detrimental to the nanocomposite morphology resulting in considerable decrease of d-spacing. Still, the mechanical properties of organofilled composites were superior to that of the carbon black or unmodified clay filled counterparts. This was attributed to efficient energy release mechanism in the presence of intercalated clays. However, the addition of carbon black to the nanocomposites led to a decrease in mechanical properties. The Payne effect was clearly seen in the nanocomposites evidenced using dynamic mechanical analysis.

  13. Controlled release of donepezil intercalated in smectite clays.

    PubMed

    Park, Jin Kuen; Choy, Young Bin; Oh, Jae-Min; Kim, Ju Young; Hwang, Seong-Ju; Choy, Jin-Ho

    2008-07-01

    The inorganic-organic hybrid for a drug delivery system was successfully realized by intercalating donepezil molecules into smectite clays (laponite XLG, saponite, and montmorillonite). According to the powder XRD patterns, TG profiles, and FT-IR spectra, it was confirmed that donepezil molecules were well stabilized in the interlayer space of clay via mono or double layer stacking. The adsorption amount and molecular structure of donepezil appeared to depend on the cation exchange capacity of the clay, which in turn, tailored the drug release patterns. Especially in the presence of a bulky cationic polymer (Eudragit E-100) in the release media, the release rate was found to be improved due to its effective replacement with intercalated donepezil molecules. Therefore, to formulate a complete drug delivery system, the hybrids were coated with Eudragit E-100 using a spray dryer, which also showed great enhancement in the release rate during a short period of time (180min). PMID:18502063

  14. Geology of the "20-foot" clay and Gardiners clay in southern Nassau and southwestern Suffolk counties, Long Island, New York

    USGS Publications Warehouse

    Doriski, T.P.; Wilde-Katz, Franceska

    1983-01-01

    Data from 1978-79 drilling was compiled with information from previous reports and historical records to prepare surface contour and isopach maps of the ' 20-foot ' clay and Gardiners Clay in southern Nassau and southwestern Suffolk Counties. These units are major confining layers in the upper part of the groundwater reservoir along Long Island 's south shore. Where present, they influence the groundwater flow patterns locally. The ' 20-foot ' clay, previously mapped in Nassau County only, was found in test borings in Suffolk County also. Its surface altitude ranges from 20 to 40 ft below NGVD (National Geodetic Vertical Datum of 1929); thickness ranges from 0 to 30 ft. The surface altitude of the Gardiners Clay ranges from 40 to 120 ft below NGVD; thickness ranges from 0 to 90 ft. Previously known discontinuities in both formations are more accurately delineated, and several new discontinuities have been inferred from the new data. The Matawan Group-Magothy Formation undifferentiated the Monmouth Group, and the Jameco Gravel directly underlie the Gardiners Clay. Revised surface altitudes of these formations are depicted on maps and cross sections of the south-shore area. (Author 's abstract)

  15. Kinetic study of aluminum adsorption by aluminosilicate clay minerals

    SciTech Connect

    Walker, W.J.; Cronan, C.S.; Patterson, H.H.

    1988-01-01

    The adsorption kinetics of Al/sup 3 +/ by montmorillonite, kaolinite, and vermiculite were investigated as a function of the initial Al concentration, the surface area of the clay, and H/sup +/ concentration, at 25/sup 0/, 18/sup 0/, and 10/sup 0/C. In order to minimize complicated side reactions the pH range was kept between 3.0 and 4.1. Results showed that the adsorption rate was first order with respect to both the initial Al concentration and the clay surface area. Changes in pH within this narrow range had virtually no effect on adsorption rate. This zero order reaction dependence suggested that the H/sup +/, compared to Al, has a weak affinity for the surface. The rates of adsorption decreased in the order of montmorillonite > kaolinite > vermiculite when compared on the basis of equal surface areas, but changed to kaolinite > montmorillonite > vermiculite when the clays were compared on an equal exchange capacity basis. The calculated apparent activation energies were < 32 kJ mol/sup -1/, indicating that over the temperature range of the study the adsorption process is only marginally temperature sensitive. The mechanism is governed by a simple electrostatic cation exchange involving outer sphere complexes between adsorbed Al and the clay surface. Vermiculite, may have a second reaction step governed by both electrostatic attraction and internal ion diffusion. Equilibrium constants for the formation of an adsorbed Al clay complex were also estimated and are 10/sup 5.34/, 10/sup 5.18/, and 10/sup 4.94/ for kaolinite, montmorillonite, and vermiculite, respectively, suggesting that these clays could play a significant role in controlling soil solutions Al concentrations.

  16. Complex resistivity signatures of ethanol in sand-clay mixtures

    USGS Publications Warehouse

    Personna, Yves Robert; Slater, Lee; Ntarlagiannis, Dimitrios; Werkema, Dale; Szabo, Zoltan

    2013-01-01

    We performed complex resistivity (CR) measurements on laboratory columns to investigate changes in electrical properties as a result of varying ethanol (EtOH) concentration (0% to 30% v/v) in a sand–clay (bentonite) matrix. We applied Debye decomposition, a phenomenological model commonly used to fit CR data, to determine model parameters (time constant: τ, chargeability: m, and normalized chargeability: mn). The CR data showed a significant (P ≤ 0.001) time-dependent variation in the clay driven polarization response (~ 12 mrad) for 0% EtOH concentration. This temporal variation probably results from the clay–water reaction kinetics trending towards equilibrium in the sand–clay–water system. The clay polarization is significantly suppressed (P ≤ 0.001) for both measured phase (ϕ) and imaginary conductivity (σ″) with increasing EtOH concentration. Normalized chargeability consistently decreases (by up to a factor of ~ 2) as EtOH concentration increases from 0% to 10% and 10 to 20%, respectively. We propose that such suppression effects are associated with alterations in the electrical double layer (EDL) at the clay–fluid interface due to (a) strong EtOH adsorption on clay, and (b) complex intermolecular EtOH–water interactions and subsequent changes in ionic mobility on the surface in the EDL. Changes in the CR data following a change of the saturating fluid from EtOH 20% to plain water indicate strong hysteresis effects in the electrical response, which we attribute to persistent EtOH adsorption on clay. Our results demonstrate high sensitivity of CR measurements to clay–EtOH interactions in porous media, indicating the potential application of this technique for characterization and monitoring of ethanol contamination in sediments containing clays.

  17. Environmental Hf-Nd isotopic decoupling in World river clays

    NASA Astrophysics Data System (ADS)

    Bayon, Germain; Skonieczny, Charlotte; Delvigne, Camille; Toucanne, Samuel; Bermell, Sylvain; Ponzevera, Emmanuel; André, Luc

    2016-03-01

    The hafnium and neodymium radiogenic isotope systems behave differently during Earth surface processes, causing a wide dispersion of Hf and Nd isotopic compositions in sediments and other sedimentary rocks. The decoupling between Hf and Nd isotopes in sediments is generally attributed to a combination of preferential sorting of zircon during sediment transport and incongruent weathering processes on continents. In this study, we analysed size-fractions of sediment samples collected near the mouth of 53 rivers worldwide to better understand the factors controlling the distribution of Hf and Nd isotopes in sediments. Our results for rivers draining old cratonic areas and volcanic provinces demonstrate that both granite and basalt weathering can lead to significant grain-size dependent Hf isotopic variability. While silt-size fractions mainly plot along the Terrestrial Array, World river clays are systematically shifted towards more radiogenic Hf isotopic compositions, defining together with published data a new Clay Array (εHf = 0.78 ×εNd + 5.23). The Hf-Nd isotope decoupling observed in volcanogenic sediments is best explained by selective alteration of Lu-rich mineral phases (e.g. olivine) and preferential enrichment of resistant unradiogenic minerals, such as spinel and ilmenite, in silt fractions. We also show that the extent to which World river clays deviate from the Clay Array (ΔεHf clay) is not linked to the presence of zircons. Instead, it correlates positively with weathering indices and climatic parameters (temperature, rainfall) of the corresponding drainage basins. Overall, these findings demonstrate that the distribution of Hf-Nd isotopes in clay-size sediments is related to a large extent to weathering conditions on continents, although the precise mechanisms controlling this relationship remain unclear. We finally propose that the Hf-Nd isotope pair proxy could be used in palaeoenvironmental studies to provide semi-quantitative information on

  18. Clay content evaluation in soils through GPR signal processing

    NASA Astrophysics Data System (ADS)

    Tosti, Fabio; Patriarca, Claudio; Slob, Evert; Benedetto, Andrea; Lambot, Sébastien

    2013-10-01

    The mechanical behavior of soils is partly affected by their clay content, which arises some important issues in many fields of employment, such as civil and environmental engineering, geology, and agriculture. This work focuses on pavement engineering, although the method applies to other fields of interest. Clay content in bearing courses of road pavement frequently causes damages and defects (e.g., cracks, deformations, and ruts). Therefore, the road safety and operability decreases, directly affecting the increase of expected accidents. In this study, different ground-penetrating radar (GPR) methods and techniques were used to non-destructively investigate the clay content in sub-asphalt compacted soils. Experimental layout provided the use of typical road materials, employed for road bearing courses construction. Three types of soils classified by the American Association of State Highway and Transportation Officials (AASHTO) as A1, A2, and A3 were used and adequately compacted in electrically and hydraulically isolated test boxes. Percentages of bentonite clay were gradually added, ranging from 2% to 25% by weight. Analyses were carried out for each clay content using two different GPR instruments. A pulse radar with ground-coupled antennae at 500 MHz centre frequency and a vector network analyzer spanning the 1-3 GHz frequency range were used. Signals were processed in both time and frequency domains, and the consistency of results was validated by the Rayleigh scattering method, the full-waveform inversion, and the signal picking techniques. Promising results were obtained for the detection of clay content affecting the bearing capacity of sub-asphalt layers.

  19. Origin of life and iron-rich clays

    NASA Technical Reports Server (NTRS)

    Hartman, H. H.

    1986-01-01

    The premise that life began with self-replicating iron-rich clays is explored. In association with these clays and UV light, polar organic molecules, such as oxalic acid, were synthesized. The carbonaceous chondrites have both iron-rich clays and organic molecules. It is convenient to classify meteoritic organic matter into 3 categories: insoluble polymer, hydrocarbons and polar organics (soluble in water). Recent work on the delta D, delta N-15 and delta C-13 has made it clear that these three fractions have been made by three different mechanisms. A significant fraction of the insoluble polymer has a delta-D which suggests that it was made in an interstellar medium. The hydrocarbons seem to have been made on a parent body by a Fischer-Tropsch mechanism. The polar organics were probably synthesized in a mixture of carbonate (NH4)2CO3, Fe(++) ion and liquid water by radiolysis. In a set of experiments the radiolysis of (NH4)2CO3 in the presence and absence of Fe(++) ion has been examined. The synthesis of glycine in the presence of Fe(++) ion is 3-4 times that in the absence of ferrous ion. The effects of the addition of hydrocarbons to this mixture are explored. Iron-rich clays at low temperature and pressure are synthesized. So far the results are not sufficiently crystalline to look for replication. It should be noted that organic chelating agents such as oxalic acid do increase the crystallinity of the clays but not sufficiently. The hydrothermal synthesis of iron-rich clays is being examined.

  20. Acid activation of bentonites and polymer-clay nanocomposites.

    SciTech Connect

    Carrado, K. A.; Komadel, P.; Center for Nanoscale Materials; Slovak Academy of Sciences

    2009-04-01

    Modified bentonites are of widespread technological importance. Common modifications include acid activation and organic treatment. Acid activation has been used for decades to prepare bleaching earths for adsorbing impurities from edible and industrial oils. Organic treatment has sparked an explosive interest in a class of materials called polymer-clay nanocomposites (PCNs). The most commonly used clay mineral in PCNs is montmorillonite, which is the main constituent of bentonite. PCN materials are used for structural reinforcement and mechanical strength, for gas permeability barriers, as flame retardants, and to minimize surface erosion (ablation). Other specialty applications include use as conducting nanocomposites and bionanocomposites.

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

    NASA Astrophysics Data System (ADS)

    Allard, Th.; Balan, E.; Calas, G.; Fourdrin, C.; Morichon, E.; Sorieul, S.

    2012-04-01

    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 π 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

  2. Synthetic clay excels in {sup 90}Sr removal

    SciTech Connect

    Komarneni, Sridhar; Kodama, Tatsuya; Paulus, William J.; Carlson, C.

    2000-06-01

    Tests with actual ground water from Hanford site, and fundamental studies of 2Na{sup +}{yields}Sr{sup 2+} exchange equilibria revealed that a synthetic clay is extremely selective for {sup 90}Sr with a high capacity for uptake. Comparative studies with existing Sr selective ion exchangers clearly revealed that the present synthetic clay exhibited the best performance for {sup 90}Sr removal from actual ground water collected from three different locations at Hanford. This novel Sr ion sieve is expected to be useful for the decontamination of the environment after accidental release and contamination with {sup 90}Sr. (c) 2000 Materials Research Society.

  3. Differentiation of pleistocene deposits in northeastern Kansas by clay minerals

    USGS Publications Warehouse

    Tien, P.-L.

    1968-01-01

    Seventy-four samples from eight stratigraphic sections of lower Pleistocene glacial and glaciofluvial deposits in Doniphan County, extreme northeastern Kansas, were analyzed using X-ray diffraction techniques. Clay-mineral assemblages of the <2 ?? fraction of these deposits are nearly identical, consisting of a mixed-layer clay mineral associated with minor amounts of kaolinite and illite. An attempt was made to differentiate units of till and nontill deposits by using the relative intensities of 001 reflections of "mixed-layer mineral," kaolinite, and illite. At least two tills were recognizable. Associated nontill deposits, could not be differentiated from one another, although the nontills are easily distinguished from tills. ?? 1968.

  4. Innovative treatment for TCE-contaminated saturated clay soils

    SciTech Connect

    West, O.R.; Cameron, P.A.; Smuin, D.R.

    1995-12-31

    This paper describes the evaluation of mixed region vapor stripping (MRVS) coupled with calcium oxide conditioning for removing trichloroethylene (TCE) for a site underlain by saturated clay soils. Volatile organic compound removal during MRVS with and without calcium oxide conditioning were simulated using a previously developed model. The results of the modeling were compared with laboratory MRVS tests on undisturbed soil cores taken from the study site. The modeling results were consistent with laboratory simulations of MRVS on field-contaminated soils from the study site, and showed that calcium oxide conditioning is an effective method for enhancing VOC removal efficiencies in saturated clay soils.

  5. XAFS Study of As in K-T Boundary Clays

    NASA Astrophysics Data System (ADS)

    Sakai, Shunsuke; Yoshiasa, Akira; Arima, Hiroshi; Okube, Maki; Numako, Chiya; Sato, Tsutomu

    2007-02-01

    Local structure around arsenic atoms in K-T boundary clays was studied by As K-edge XAFS spectroscopy. The threshold E0 energy of As and the characterization of the white peak of XANES spectra agree well with the values of As(+5) minerals like Zn2(AsO4)2(OH)22H2O and CaCu(AsO4)(OH) according to the comparison with several types of arsenic minerals. This indicates that arsenic is in a high oxidation state As(+5) and occupies the AsO4 tetrahedral site of a mineral in K-T boundary clays.

  6. Pillared smectite clay coatings for ceramic-matrix composites

    SciTech Connect

    Jagota, S.; Harmer, M.A.; Lemon, M.F.; Jagota, A.; McCarron, E.M. III.

    1995-08-01

    This paper describes a novel route for the low-temperature formation of mullite, from pillared smectite clay precursors, for use as fiber coatings in ceramic-matrix composites. In particular, alumina-pillared bentonite converts in part to mullite at the unusually low temperature of about 800 C. The clay precursors display excellent film-forming capability and have been coated onto silicon carbide fibers. Mechanical tests on composites of the coated fibers and a borosilicate glass demonstrate their success as debond coatings, suggesting that this approach is a viable and simple route to oxide coatings for fibers.

  7. Conducting polymer/clay nanocomposites and their applications.

    PubMed

    Fang, Fei Fei; Choi, Hyoung Jin; Joo, Jinsoo

    2008-04-01

    This review aims at reporting on interesting and potential aspects of conducting polymer/clay nanocomposites with regard to their preparation, characteristics and engineering applications. Various conducting polymers such as polyaniline, polypyrrole and copolyaniline are introduced and three different preparation methods of synthesizing conducting polymer/clay nanocomposites are being emphasized. Morphological features, structure characteristics and thermal degradation behavior are explained based on SEM/TEM images, XRD pattern analyses and TGA/DSC graphs, respectively. Attentions are also being paid on conductive/magnetic performances as well as two potential applications in anti-corrosion coating and electrorheological (ER) fluids. PMID:18572558

  8. Reactivity of Fe(II) species associated with clay minerals.

    PubMed

    Hofstetter, Thomas B; Schwarzenbach, René P; Haderlein, Stefan B

    2003-02-01

    Mineral-bound Fe(II) species represent important natural reductants of pollutants in the anaerobic subsurface. At clay minerals, three types of Fe(II) species in fundamentally different chemical environments may be present simultaneously, i.e., structural Fe(II), Fe(II) complexed by surface hydroxyl groups, and Fe(II) bound by ion exchange. We investigated the accessibility and reactivity of these three types of Fe(II) species in suspensions of two different clay minerals containing either ferrous iron-bearing nontronite or iron-free hectorite. Nitroaromatic compounds (NACs) exhibiting different sorption behavior on clays were used to probe the reactivity of the various types of reduced iron species. The clay treatment allowed for a preparation of nontronite and hectorite surfaces with Fe(II) adsorbed by surface hydroxyl groups at the edge surfaces. Furthermore, hectorite suspensions with additional Fe(II) bound to the ion exchange sites at the basal siloxane surfaces were set up. We found that both structural Fe(II) and Fe(II) complexed by surface hydroxyl groups of nontronite reduced the NACs to anilines. An electron balance revealed that more than 10% of the total iron in nontronite was reactive Fe(II). Fe(II) bound by ion exchange did not contribute to the observed reduction of NACs. Reversible adsorption of the NACs at the basal siloxane surface of the clays strongly retarded NAC reduction, even in the presence of high concentrations of Fe(II) bound by ion exchange to the basal siloxane surfaces. Our work shows that in natural systems a fraction of the total Fe(II) present on clays may contribute to the pool of highly reactive Fe(II) species in the subsurface. Furthermore, this work may help to distinguish between Fe(II) species of different reactivity regarding pollutant reduction. Although structural iron in clays represents only a small fraction of the total iron pool in soils and aquifers, reactive Fe(II) species originating from the reduction of

  9. Midwifery models: students' conceptualization of a midwifery philosophy in clay.

    PubMed

    Walker, Deborah S

    2007-01-01

    Formulating a professional and personal philosophy statement assists nurses and midwives in clarifying focus and direction. It also facilitates grounding of the nursing and midwifery professions or professionals by enabling the identification of both shared beliefs and unique elements. The purpose of this activity was to assist beginning student nurse-midwives (SNMs) in exploring the intersection of their own and the profession's philosophy. Through the creation of a clay representation of their philosophical model, eight SNMs expressed their midwifery philosophies at the beginning of their clinical sequence by sculpting them in clay and then described their sculptures and how they exemplified their philosophies. PMID:17207753

  10. Cracking of Clay Due to Contact with Waste Chlorinated Solvents

    NASA Astrophysics Data System (ADS)

    Otero, M.; Ayral, D.; Shipan, J.; Goltz, M. N.; Huang, J.; Demond, A. H.

    2012-12-01

    Clays are known to crack upon desiccation. Desiccation cracks of up to 3 cm wide have been reported in natural soils. This raises the question if a similar behavior is seen when a dense non-aqueous phase liquids (DNAPL) waste is in contact with clay. The contact with organic liquids causes the clay structure to shrink, leading to the formation of cracks. Moreover, DNAPL waste not only contains the organic liquid solvent but also includes surface-active solutes or surfactants. Such solutes can enhance the interaction of the organic solvents with the clay. This research will assess whether or not contact with chlorinated organic waste causes cracking. In order to evaluate the possibility of cracking in the clay, microcosms have been constructed that mimic aquifer systems, consisting of a saturated layer of sand, a saturated layer of bentonite clay and a 2.5 cm layer of either pure chlorinated solvents or DNAPL waste. The onset of cracking for the microcosm with tetrachloroethylene (PCE) waste as the DNAPL layer occurred after ten days of contact. Similarly, at eight days, cracks were observed in a microcosm containing trichloroethylene (TCE) waste . Forty-four days later, the length and number of cracks have grown considerably; with a total crack length of 50 cm on a surface of 80 cm2 in the microcosm containing PCE waste. On the other hand it took approximately 161 days for the clay layer in the microcosm containing pure PCE to crack. To quantity the degree of cracking, crack maps were developed using the image software, Image J. Characteristics like crack length, crack aperture, and the percentage of total length for a range of apertures were calculated using this software. For example, for the PCE waste microcosm, it was calculated that 3.7% of the crack length had an aperture of 100-300 microns, 15.1% of the crack length had an aperture of 300-500 microns, 29.7% of the crack length had an aperture of 500-700 microns, 40.1% of the crack length had an aperture of

  11. Smart Clays: SAFOD Samples Confirm the Key Role of Newly-formed Clays in Shallow Fault Zones

    NASA Astrophysics Data System (ADS)

    Schleicher, A.; van der Pluijm, B.; Warr, L. N.

    2013-12-01

    Analysis of fault rocks from drill-cores of the San Andreas Fault Observatory at Depth (SAFOD) project in Parkfield (CA) confirm our original hypothesis that active clay growth can occur locally at shallow conditions and that such clay localization affect fault mechanics and fault creep in particular. SAFOD fault rocks contain a variety of newly formed clay minerals including smectite, illite-smectite and chlorite-smectite, as well as illite and chlorite. Brecciated host rock fragments are abundantly coated by polished and/or striated thin-films of hydrated clay minerals, creating an interconnected and pervasive network of displacement surfaces. Ar encapsulation dating of mixed-layer nanocoatings demonstrates recent crystallization and reveal an 'older' fault strand (~8 Ma) at 3066 m measured depth and a 'younger' fault strand (~4 Ma) at 3296 m measured depth. Today, the younger strand is the site of active creep behavior, demonstrating continued (re)activation of clay-weakened zones. Recent experimental work on aseismically creeping segments of SAFOD samples showed frictional strengths that are significantly weaker than neighboring wall rocks, offering independent validation of our model. Using a range of analytical methods that include X-ray diffraction, X-ray goniometry, elemental analysis and electron microscopy, we determined the location and nature of smectitic clay minerals in borehole samples, to assess the extent of smectitic phases in space and depth, any fault zone fabric development, and the swelling behavior of smectitic phases within the fault zone. Beyond the occurrence of illite-smectite in these relatively shallow fault rocks, the localized concentration of chlorite-smectite can extend the role of smectitic clays to depths down to ~10 km. We conclude that ultrathin hydrous clay films, or nanocoatings, on displacement surfaces play a key role in influencing weak fault and creep behavior along the San Andreas Fault at Parkfield, and likely in shallow

  12. Effect of clay surface silylation and dispersion method on the mechanical properties of epoxy-clay composites

    NASA Astrophysics Data System (ADS)

    Romeo, V.; Piscitelli, F.; Scamardella, A. M.; Amendola, E.; Lavorgna, M.; Mensitieri, G.; Acierno, D.

    2010-06-01

    Epoxy-clay nanocomposites were prepared dispersing both pristine and functionalized sodium montmorillonite powders (1 and 3 wt%) in epoxy resin by means of sonication and sonication/ball-milling high energy mixing processes. Silylation reaction of sodium montmorillonite (Na-MMT) was performed by using 3-aminopropyltriethoxysilane (A1100) and N-2-aminoethyl)-3-aminopropyltrimethoxysilane (A1120) as coupling agents. Morphological investigations showed that the MMT stacks are only slightly intercalated. However the surface modification of MMT clays improves the interfacial interaction with epoxy resins and the nanocomposites obtained through sonication exhibit enhanced mechanical properties compared to the nanocomposites prepared from pristine Na-MMT.

  13. Speciation of neptunium during sorption and diffusion in natural clay

    NASA Astrophysics Data System (ADS)

    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.

  14. First Direct Detection of Clay Minerals on Mars

    NASA Technical Reports Server (NTRS)

    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.

  15. Placed on a Pedestal: Famous Faces in Clay

    ERIC Educational Resources Information Center

    Walkup, Nancy

    2010-01-01

    Artists have created portraits of people for thousands of years. In sculpture, a portrait of a person's face often includes the neck and part of the shoulders and chest. These artworks are called portrait busts. In this article, the author describes how her fifth-grade students created clay portrait busts on pedestal columns. The objectives are…

  16. Interactions of Monovalent Organic Cations with Pillared Clays.

    PubMed

    Mishael; Rytwo; Nir; Crespin; Annabi-Bergaya; Van Damme H

    1999-01-01

    Interactions between an acid-activated pillared clay and several organic cations including dyes (methylene blue, MB; crystal violet, CV; acriflavin, AF) and benzyl derivatives (benzyltrimethylammonium, BTMA; benzyltriethylammonium, BTEA) were studied by adsorption measurements and X-ray diffraction. When the dyes were adsorbed from low ionic strength solutions, adsorption was irreversible but saturated at levels below the cation exchange capacity (CEC) of the clay (0.6 meq/g). The difference with CEC value was largest for CV. This mode of adsorption was interpreted in terms of interlayer adsorption with steric hindrance in the pillared galleries. On the other hand, when the dyes were adsorbed from high ionic strength solutions, adsorption levels well beyond the CEC of the clay could be reached, in particular for MB and CV. This was interpreted in terms of a second adsorption mode, involving formation of molecular aggregates on the outer surface of the clay, as evidenced by X-ray diffraction. The behavior of the cationic benzyl derivatives was markedly different, with an adsorption level always below the CEC and a decrease of adsorption as the ionic strength was increased, as expected for non-complex-forming cations. Copyright 1999 Academic Press. PMID:9878144

  17. 42. PRESSING A SLAB OF CLAY ONTO A MOSAIC MOLD. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    42. PRESSING A SLAB OF CLAY ONTO A MOSAIC MOLD. THE MOLD, WHICH HAS A RAISED DESIGN, LEAVES AND OUTLINE IN THE SLAB, THE PIECES THUS DEFINED, ARE THEN CUT APART TO BE FIRED SEPARATELY AND REASSEMBLED. - Moravian Pottery & Tile Works, Southwest side of State Route 313 (Swamp Road), Northwest of East Court Street, Doylestown, Bucks County, PA

  18. Slope Stability of Geosynthetic Clay Liner Test Plots

    EPA Science Inventory

    Fourteen full-scale field test plots containing five types of geosynthetic clay liners (GCLs) were constructed on 2H:IV and 3H:IV slopes for the purpose of assessing slope stability. The test plots were designed to simulate typical final cover systems for landfill. Slides occurr...

  19. Technopotters and Webs of Clay: Digital Possibilities for Teaching Ceramics

    ERIC Educational Resources Information Center

    Weida, Courtney Lee

    2007-01-01

    In this article, the author examines ways in which the Internet is changing the way ceramicists teach, learn, and work. She addresses the curricular issue of how Web resources may supplement ceramic art history and extend student-centered learning. The author also explores the nature of the interplay between computer technology and clay. (Contains…

  20. The radiolysis and radioracemization of amino acids on clays

    NASA Technical Reports Server (NTRS)

    Bonner, W. A.; Hall, H.; Chow, G.; Yi, L.; Lemmon, R. M.

    1985-01-01

    The effects of the surfaces of kaolinite and bentonite clays on the radiolysis and radioracemization of L-leucine and its hydrochloride salt have been investigated experimentally. L-leucine and its hydrochloride salt were deposited on the clays and the amino acid/clay preparations were irradiated by a Co-60 gamma-ray source which induced 2-89 percent radiolysis. The efficiency of radiolysis and radioracemization were measured using gas chromatography. Results were obtained for leucine in 0.1 M aqueous solution for comparison with the clay-deposted leucine and leucine hydrochloride. It is found that radiolysis and radioracemization in the samples occurred according to a pseudo-first-order rate law. Comparison of the specific rate constants showed that leucine and its hydrochloride salt were the most resistant to both radiolysis and radioracemization, followed by leucine and its hydrochloride salt on kaolin. Leucine and its HCl salt on bentonite, and leucine in aqueous solution were found to be the least resistant to radiolysis and radioracemization. The experimental results are intepreted with respect to the Vester-Ulbricht mechanism for the origin of optical activity.

  1. Clay Caterpillars: A Tool for Ecology & Evolution Laboratories

    ERIC Educational Resources Information Center

    Barber, Nicholas A.

    2012-01-01

    I present a framework for ecology and evolution laboratory exercises using artificial caterpillars made from modeling clay. Students generate and test hypotheses about predation rates on caterpillars that differ in appearance or "behavior" to understand how natural selection by predators shapes distribution and physical characteristics of…

  2. Use of a clay modeling task to reduce chocolate craving.

    PubMed

    Andrade, Jackie; Pears, Sally; May, Jon; Kavanagh, David J

    2012-06-01

    Elaborated Intrusion theory (EI theory; Kavanagh, Andrade, & May, 2005) posits two main cognitive components in craving: associative processes that lead to intrusive thoughts about the craved substance or activity, and elaborative processes supporting mental imagery of the substance or activity. We used a novel visuospatial task to test the hypothesis that visual imagery plays a key role in craving. Experiment 1 showed that spending 10 min constructing shapes from modeling clay (plasticine) reduced participants' craving for chocolate compared with spending 10 min 'letting your mind wander'. Increasing the load on verbal working memory using a mental arithmetic task (counting backwards by threes) did not reduce craving further. Experiment 2 compared effects on craving of a simpler verbal task (counting by ones) and clay modeling. Clay modeling reduced overall craving strength and strength of craving imagery, and reduced the frequency of thoughts about chocolate. The results are consistent with EI theory, showing that craving is reduced by loading the visuospatial sketchpad of working memory but not by loading the phonological loop. Clay modeling might be a useful self-help tool to help manage craving for chocolate, snacks and other foods. PMID:22369958

  3. Modified clays for waste containment and pollutant attenuation

    SciTech Connect

    Lo, I.M.C.; Mak, R.K.M.; Lee, S.C.H.

    1997-01-01

    In this study, the use of organically modified clay to remove the high-strength organic pollutants in leachate as well as reduce its liquid flow was investigated. Various physical and chemical factors that may affect the suitability of using the modified clay in removing and retarding the movement of contaminants have been examined. These factors include the structural stability of the modified clay, soil and swelling properties, sorption capacity for nonpolar and polar organics at different pH solutions, and chemical permeants on clay permeability under different effective stresses. The uptake of eight organics (benzene, toluene, o-xylene, ethylbenzene, phenol, 2-chlorophenol, 2,4-dichlorophenol, and 2,4,6-trichlorophenol) by organoclay BB-40 is found to be significant and increases with an increase in their hydrophobicity. The hydraulic conductivities of organoclay BB-40 under an effective stress of 70 kN/m{sup 2} ({approximately}10 psi) are 7 {times} 10{sup {minus}9} cm/s to tap water, 1.6 {times} 10{sup {minus}8} cm/s to landfill codisposal leachate, and 1.1 {times} 10{sup {minus}7} cm/s to synthetic leachate. The experimental results suggest that the use of organoclay as a liner material would provide a barrier with the ability to effectively remove dissolved organic contaminants, and to resist the flow of leachate.

  4. The effect of switchable water additives on clay settling.

    PubMed

    Chen, Chien-Shun; Lau, Ying Yin; Mercer, Sean M; Robert, Tobias; Horton, J Hugh; Jessop, Philip G

    2013-01-01

    The recycling of process water from strip mining extractions is a very relevant task both industrially and environmentally. The sedimentation of fine tailings during such processes, however, can often require long periods of time and/or the addition of flocculants which make later water recycling difficult. We propose the use of switchable water additives as reversible flocculants for clay/water suspensions. Switchable water additives are compounds such as diamines that make it possible to reversibly control the ionic strength of an aqueous solution. Addition of CO(2) to such an aqueous solution causes the ionic strength to rise dramatically, and the change is reversed upon removal of the CO(2). These additives, while in the presence of CO(2), promote the aggregation of clay tailings, reduce settling times, and greatly increase the clarity of the liberated water. The removal of CO(2) from the liberated water regenerates a low ionic strength solution that does not promote clay aggregation and settling until CO(2) is added again. Such reversible behavior would be useful in applications such as oil sands separations in which the recycled water must not promote aggregation. When added to kaolinite and montmorillonite clay suspensions, switchable water provided process waters of lower turbidity than those additives from inorganic salts or by CO(2)-treatment alone. When recollected, the switchable water supernatant was shown to be recyclable over three cycles for enhanced settling of kaolinite. PMID:22945593

  5. Birds of a Feather... and Clay, Wire, Tissue and Paint!

    ERIC Educational Resources Information Center

    Feiner, Lois

    2011-01-01

    What began as a review lesson in clay construction quickly became a fun learning experience filled with inspiring conversations and creatively painted birds. This lesson was successful from beginning to end, with a final reward when the artwork was displayed. The author describes the process of working on this project and shares how the students…

  6. Field Performance Of Three Compacted Clay Landfill Covers

    EPA Science Inventory

    A study was conducted at sites in subtropical Georgia, seasonal and humid Iowa, and arid southeastern California to evaluate the field hydrology of compacted clay covers for final closure of landfills. Water balance of the covers was monitored with large (10 by 20 m ), instrumen...

  7. Stirring the Waters: The Influence of Marie Clay.

    ERIC Educational Resources Information Center

    Gaffney, Janet S., Ed.; Askew, Billie J., Ed.

    Celebrating Marie Clay as a major theorist of child literacy acquisition, this book presents 15 essays by distinguished scholars that reflect on her contributions to the field of early literacy; early childhood, bilingual, and special education; developmental, cognitive, and school psychology; assessment; teacher education; professional…

  8. Disassembly of the cystovirus ϕ6 envelope by montmorillonite clay.

    PubMed

    Block, Karin A; Trusiak, Adrianna; Katz, Al; Gottlieb, Paul; Alimova, Alexandra; Wei, Hui; Morales, Jorge; Rice, William J; Steiner, Jeffrey C

    2014-02-01

    Prior studies of clay-virus interactions have focused on the stability and infectivity of nonenveloped viruses, yielding contradictory results. We hypothesize that the surface charge distribution of the clay and virus envelope dictates how the components react and affect aggregation, viral stability, and infectivity. The bacteriophage Cystoviridae species φ6 used in this study is a good model for enveloped pathogens. The interaction between φ6 and montmorillonite (MMT) clay (the primary component of bentonite) is explored by transmission electron microscopy. The analyses show that MMT-φ6 mixtures undergo heteroaggregation, forming structures in which virtually all the virions are either sequestered between MMT platelet layers or attached to platelet edges. The virions swell and undergo disassembly resulting in partial or total envelope loss. Edge-attached viral envelopes distort to increase contact area with the positively charged platelet edges indicating that the virion surface is negatively charged. The nucleocapsid (NCs) remaining after envelope removal also exhibit distortion, in contrast to detergent-produced NCs which exhibit no distortion. This visually discernible disassembly is a mechanism for loss of infectivity previously unreported by studies of nonenveloped viruses. The MMT-mediated sequestration and disassembly result in reduced infectivity, suggesting that clays may reduce infectivity of enveloped pathogenic viruses in soils and sediments. PMID:24357622

  9. Clay mineralogy of Devonian shales in the Appalachian basin

    SciTech Connect

    Hosterman, J.W.; Whitlow, S.T.

    1981-01-01

    A study of the clay mineralogy of the Devonian black shales of the Appalachian basin was undertaken to help predict areas for potential gas resources. Illite (2m) recrystallized during diagenesis is more or less uniformly present throughout all shale units. Chlorite formed during low grade metamorphism is least abundant in the younger units and more abundant in the older units. Illite-smectite mixed-layer clay, which supplied the material for the formation of chlorite, is most abundant in the younger units and least abundant in the older units. Illite-chlorite mixed-layer clay occurs as a trace in all shale units. Kaolinite, the only unaltered detrital clay mineral, occurs in ca. 25 to 30% of the samples. The source of the kaolinite appears to have been to the east and northeast of the basin of deposition. The color of the shale units is primarily due to the organic content; however, those shales that contain calcite are darker than those that do not for equal amounts of organic carbon. 24 references.

  10. 66. MISSISSIPPI, CLAY CO. TIBBEE Tibbee Cr. ROAD BRIDGE On ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    66. MISSISSIPPI, CLAY CO. TIBBEE Tibbee Cr. ROAD BRIDGE On old Columbus-West Point rd., just N of Tibbee Aerial view from N of single lane truss bridge. David J. Kaminsky, Architectural Photography, Atlanta, Ga. Aug 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

  11. Sorption and diffusion of chlorinated methanes in moist clay

    SciTech Connect

    Cabbar, H.C.; Varol, N.; McCoy, B.J.

    1998-06-01

    The dynamic behavior of chlorinated methanes in clays exposed to relative humidities (RH) from 0 to 80% was investigated with the single-pellet pulse-response moment technique. Values of effective diffusion coefficients obtained from zeroth moment analysis differed only slightly for dry and moist clay pellets. When the clay pellet was dry, equilibrium adsorption constants of dichloromethane (D), trichloromethane (T), and carbon tetrachloride (C) at the gas-mineral interface were determined from first moments to be 118, 92, and 90, respectively. Dryness factors (dry fraction of surface area) for clays with RH of 5, 20, 40, and 60% were also calculated from first moments as 0.5, 0.1, 0.04, and 0.01, respectively. When the pore surfaces were covered with the water film (dryness factor was 0 for the pellet at RH 80%), overall equilibrium adsorption constants for the same tracers (D, T, C) at the gas-water and water-mineral interfaces were determined to be 7.5, 7.2, and 3.6, respectively.

  12. ATTENUATION OF POLLUTANTS IN MUNICIPAL LANDFILL LEACHATE BY CLAY MINERALS

    EPA Science Inventory

    The first part of this project was a laboratory column study of attenuation of pollutants in municipal solid waste landfill leachate by mixtures of sand and calcium-saturated clays. K, NH4, Mg, Si, and Fe were moderately attenuated; and the heavy metals Pb, Cd, Hg, and Zn were st...

  13. Picloram and Aminopyralid Sorption to Soil and Clay Minerals

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  14. Experiencing Clay: Inquiry-Based Learning and Assessment for Learning

    ERIC Educational Resources Information Center

    Mui, Ma So

    2010-01-01

    This article presents an examination of the effects of using an inquiry-based learning pedagogy to teach ceramics to pre-service teachers (my students) at the Hong Kong Institute of Education. At the beginning of the study the students were asked to conduct experiments on the properties of clay. The results indicate that half of them were able to…

  15. Barrier and Mechanical Properties of Starch-Clay Nanocomposite Films

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The poor barrier and mechanical properties of biopolymer-based food packaging can potentially be enhanced by the use of layered silicates (nanoclay) to produce nanocomposites. In this study, starch-clay nano-composites were synthesized by a melt extrusion method. Natural (MMT) and organically modifi...

  16. Rate-dependent undrained shear behavior of saturated clay

    SciTech Connect

    Sheahan, T.C.; Ladd, C.C.; Germaine, J.T.

    1996-02-01

    The paper describes results from 250 K{sub 0} consolidated-undrained triaxial compression tests on resedimented Boston blue clay using a computer-automated triaxial apparatus with lubricated end platens and a midheight pore-pressure measurement device. Specimens were consolidated to four over consolidation ratios (OCR = 1, 2, 4, or 8), and for each OCR, undrained shear was performed using four axial strain rates (0.05%, 0.5%, 5%, and 50%/h). The results show that the undrained strength (s{sub u}) rate sensitivity (percent increase in s{sub u} per log cycle strain rate) across the two fastest strain rates does not vary with OCR and equals about 9%. However, across the three slower rates, increases in OCR cause a consistent decrease in the rate sensitivity that reaches zero at OCR = 8. For high OCR clay, increases in s{sub u} (if they occur) are caused by lower shear-induced pore pressures since the effective stress envelope at the peak strength does not vary with strain rate. For low OCR clay, increases in s{sub u} are caused by both lower shear-induced pore pressures and increases in the mobilized friction angle. A simple technique is proposed for modeling the rate dependent stress-strain curves of over consolidated clay.

  17. 20. BLUEPRINT, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY L.% MI. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    20. BLUEPRINT, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY L.% MI. S of MS. 50 Proposed bridge, by Phoenis Bridge Co., Phoenixville, Pa. 218-foot turn span, with load bearing. 21 May 1914. Act. size: 16X35 in. Credit: Columbus and Greenville RR, Columbus, Ms. Sarcone Photography, Columbus, Ms. Sept 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

  18. 18. BLUEPRINT, RR BRIDGE Tombigbee R. MISSISSIPPI, CLAY CO., WAVERLY ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    18. BLUEPRINT, RR BRIDGE Tombigbee R. MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. S of MS 50 Detail: 'Georgia Pacific Rwy. -- Tombigbee River Bridge Elevation' with river profile, May 16, 1888. Credit: Columbus and Greenville Rr, Columbus, Ms. DWG = S-3-342. Sarcone Photography, Columbus, Ms Sep 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

  19. Changing Faces in the Art Room: Working with Plasticine Clay.

    ERIC Educational Resources Information Center

    Skophammer, Karen

    1999-01-01

    Presents an art lesson for second-grade students that was inspired by the book "Grandpa's Face" by Eloise Greenfield. Comments that the students each wrote a descriptions of their grandfather's face, compared the artwork of Chuck Close and Vincent Van Gogh, and then made clay representations of their grandfather's face using abstract…

  20. Fine Structure of Starch-Clay Composites as Biopolymers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Midsol 50 wheat starch and 5% Cloisite clay with or without the addition of glycerin were used to prepare biopolymers in a twin-screw extruder. Early trials of sectioning the unembedded biopolymer resulted in the immediate absorption of water and subsequent dissolution of the sample due to the the ...

  1. Development and Characterization of Cellulose/clay Nanocomposites

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cotton is the most important textile fiber for apparel use and is preferred to synthetic fibers for reasons such as comfort and feel. A major drawback of cellulosic fibers is flammability. The development of cellulose/clay nanocomposites for use as flame retardant materials based on cotton is repo...

  2. Hand-Built Pottery: An Elementary Clay Project.

    ERIC Educational Resources Information Center

    Farris, Cynthia Cox

    2001-01-01

    Describes an activity that takes two class periods where fifth-grade students created hand-built pots. Explains that each child receives a clay slab. Discusses how to make the major part of the pot from two pinch pots and how to create the neck and foot. (CMK)

  3. Fine particle clay catalysts for coal liquefaction. Final technical report

    SciTech Connect

    Olson, E.S.

    1995-08-01

    In an effort to develop new disposable catalysts for direct coal liquefaction, several types of clay-supported pyrrhotite catalysts were prepared and tested. These included iron-pillared montmorillonite, mixed iron/alumina-pillared montmorillonite, iron-impregnated montmorillonite, and iron oxometallate-impregnated montmorillonite.

  4. Excimer laser ablation of polymer-clay nanocomposites

    NASA Astrophysics Data System (ADS)

    Chang, I.-Ta

    The ablation behavior of Polystyrene-Organically Modified Montmorillonite (OMMT) nanocomposites was evaluated by measuring the weight loss induced by KrF excimer laser irradiation of the nanocomposite specimens under air atmosphere. The characteristic values of ablation, ablation threshold fluence and effective absorption coefficient for polystyrene and its naonocomposites were calculated based on the weight loss data. The effects of morphology due to spatial variation in injection molded samples are also discussed in this work. Results demonstrate that both the dispersion state and the concentration of clay play important roles in excimer laser ablation. The sensitivity of threshold fluence and absorption coefficient to dispersion state of OMMT depends on the clay concentration. The excimer laser induced surface micro/nano structure formation and modification of PS-Clay Nanocomposites at various OMMT concentrations were also investigated. Scanning electron microscopy, atomic force microscopy and Fourier Transform Infrared (FTIR) spectroscopy with attenuated total reflectance accessory were utilized to analyze the ablated surface. Results show that, in general, better dispersion of OMMT leads to less continuous surface structures and more pronounced carbonyl regions on FTIR spectra. Clay nanoparticles are exposed on ablated surfaces and affect surface structure formation after irradiation by laser. A mechanism for the formation of excimer laser induced surface structures on injection molded parts is thus proposed.

  5. DETAIL OF EIGHTH (TOP) FLOOR AT CLAY AND 15TH STREETS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    DETAIL OF EIGHTH (TOP) FLOOR AT CLAY AND 15TH STREETS SHOWING ORNAMENTAL TERRA COTTA BANDING AND RELIEF PANELS. WINDOWS, WINDOW FRAMES, AND METAL CORNICE REMOVED - John Breuner & Company Building, 1515 Clay Street, Oakland, Alameda County, CA

  6. Biodegradable nanocomposites from toughened polyhydroxybutyrate and titanate-modified montmorillonite clay

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Montmorillonite clay treated with neopentyl (diallyl)oxy tri( dioctyl) pyrophosphato-titanate was used as a reinforcement for toughened bacterial bioplastic, Polyhydroxybutyrate (PHB) in order to develop novel biodegradable nanocomposites. The modified clay, PHB, toughening partner and specific comp...

  7. [Interaction of clay minerals with microorganisms: a review of experimental data].

    PubMed

    Naĭmark, E B; Eroshchev-Shak, V A; Chizhikova, N P; Kompantseva, E I

    2009-01-01

    A review of publications containing results of experiments on the interaction of microorganisms with clay minerals is presented. Bacteria are shown to be involved in all processes related to the transformation of clay minerals: formation of clays from metamorphic and sedimentary rocks, formation of clays from solutions, reversible transitions of different types of clay minerals, and consolidation of clay minerals into sedimentary rocks. Integration of these results allows to conclude that bacteria reproduced all possible abiotic reactions associated with the clay minerals, these reactions proceed much faster with the bacteria being involved. Thus, bacteria act as a living catalyst in the geochemical cycle of clay minerals. The ecological role of bacteria can be considered as a repetition of a chemical process of the abiotic world, but with the use of organic catalytic innovation. PMID:19425352

  8. Clay deposits of the Tierra Colorado district, southern Orange County, California

    USGS Publications Warehouse

    Daviess, Steven Norman; Bramlette, M.N.

    1953-01-01

    The clay of this district is being mined for fire brick by the Vitrofrax Corporation. Much of the clay contains 35 percent or more of alumina and between 1 and 2 percent of iron oxide. Production is largely from an underground mine as the best clay deposit known in the district occurs on the side of a steep hill with more than 100 feet of sandstone overlying most of it. The good clay deposits occur at the base of an Eocene sandstone formation, and overlie mottled clays with a high iron content that are residual deposits formed on an old weathered surface. Mapping indicates that the clay deposits are very lenticular, though all occur at the same stratigraphic position, and they grade laterally into sandy clay and quartz sand. Topographic relief and the dip of the strata preclude finding large areas where the clay strata have relatively little overburden.

  9. Clay microporosity in reservoir sandstones: An application of quantitative electron microscopy in petrophysical evaluation

    SciTech Connect

    Hurst, A.; Nadeau, P.H.

    1995-04-01

    Clay mineral microporosity in sandstones is measured using computer-assisted image analysis of back-scattered electron micrographs of petrographic sections. Diagenetic kaolinite has a variety of textures with microporosity values ranging from 15 to 61%. Diagenetic chlorite has a generally uniform grain-coating texture and microporosity of about 50%. Fibrous illitic clays are difficult to characterize by the same method (an average value of 63% microporosity was recorded), but analysis of stereo-pair micrographs from scanning-electron microscopy analyses reveals that illite commonly has microporosity of approximately 90%. Clay microporosity data are used to calculate effective pore volumes and volumes of clay-bound water for clay minerals in sandstones. Converting from weight percent clay to volume percent clay is important. Microporosity data are valuable input to V{sub shale} evaluation where water saturation is associated with clay mineral type, texture, and volume.

  10. Searching for reciclability of modified clays for an environmental application

    NASA Astrophysics Data System (ADS)

    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

  11. Environmental applications of radiation-induced defects in clay minerals

    NASA Astrophysics Data System (ADS)

    Allard, T.

    2011-12-01

    Radiation effects on clay minerals have been studied over the last 35 years, providing a wealth of information on environmental and geological processes. They have been applied to the reconstruction of past radioelement migrations in the geosphere, the dating of clay minerals from soils or the evolution of the physico-chemical properties under irradiation. All known radiation-induced point defects in clay minerals are detected using Electron Paramagnetic Resonance Spectroscopy. They mostly consist in electron holes located on oxygen atoms of the structure, and can be differentiated through their nature and their thermal stability. For instance, several are associated to a π orbital on a Si-O bond. One defect, namely the A-center, is stable over geological periods at ambiant temperature. These point defects are produced mainly by ionizing radiations. By contrast to point defects, it was shown that electron or heavy ion irradiation easily produces amorphization in smectites. Two main applications of radiation-induced defects in clay minerals are derived : (i) the use of defects as tracers of past radioactivity. In geosystems where the age of the clay can be constrained, migrations of radioelements can be reconstructed in natural analogues of the far field 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 laterites of the Amazon basin. (ii) The influence of radiation on clay mineral properties that remains poorly documented, although it is an important issue in various domains such as the safety assessment of the high level nuclear waste repositories. In case of a leakage of transuranic elements from the radioactive wasteform, alpha recoil nuclei would amorphize smectite after a period much lower than the disposal lifetime. By contrast, amorphisation from ionizing radiation is unlikely over 1 million years. Furthermore, it was shown that amorphization

  12. Clay with Desiccation Cracks is an Advection Dominated Environment

    NASA Astrophysics Data System (ADS)

    Baram, S.; Kurtzman, D.; Sher, Y.; Ronen, Z.; Dahan, O.

    2012-04-01

    Heavy clay sediments are regarded "safe" from the hydrological point of view due to their low hydraulic conductivities. However, the formation of desiccation cracks in dispersive clays may dramatically change their bulk hydraulic properties. The impact of desiccation cracks on water percolation, dissolved salts and contaminants transport and redox related reactions (microbial ammonium oxidation and denitrification) were investigated in 6 -12 m clay layer near a diary farm waste lagoon. The study implemented unique vadose-zone monitoring systems that enable in-situ measurements of the temporal variation of the sediment's water content along with frequent sampling of the sediment's pore water along the entire vadose zone (> 30 m). Results from four years of continuous measurements showed quick rises in sediment water content following rain events and temporal wastewater overflows. The percolation pattern indicated dominance of preferential flow through a desiccation-cracks network crossing the entire clay sediment layer. High water-propagation velocities (0.4 - 23.6 m h-1) were observed, indicating that the desiccation-crack network remains open and serves as a preferential flow pathway year-round, even at high sediment water content (~0.50 m3 m-3). The rapid percolation bypassed the most bio-geo-active parts of the soil, transporting even highly sorptive contaminants (testosterone and estrogen) in to the deep sections of the vadose zone, accelerating the underlying groundwater contamination. The ammonium and nitrate concentrations in the vadose zone and the high number of nitrifying and denitrifying bacteria (~108 gene copies gdry-sediemt-1, each) found in the sediment indicated that the entire vadose zone is aerated even at high water content conditions (~0.55 m3 m-3). The dissolved salts concentration in the pore-water and the δ2H-H2O and δ18O-H2O values of the pore-water substantially increased with depth (becoming less depleted) in the clay sediment

  13. Magnetic resonance imaging of clays: swelling, sedimentation, dissolution

    NASA Astrophysics Data System (ADS)

    Dvinskikh, Sergey; Furo, Istvan

    2010-05-01

    While most magnetic resonance imaging (MRI) applications concern medical research, there is a rapidly increasing number of MRI studies in the field of environmental science and technology. In this presentation, MRI will be introduced from the latter perspective. While many processes in these areas are similar to those addressed in medical applications of MRI, parameters and experimental implementations are often quite different and, in many respects, far more demanding. This hinders direct transfer of existing methods developed for biomedical research, especially when facing the challenging task of obtaining spatially resolved quantitative information. In MRI investigation of soils, clays, and rocks, mainly water signal is detected, similarly to MRI of biological and medical samples. However, a strong variation of water mobility and a wide spread of water spin relaxation properties in these materials make it difficult to use standard MRI approaches. Other significant limitations can be identified as following: T2 relaxation and probe dead time effects; molecular diffusion artifacts; varying dielectric losses and induced currents in conductive samples; limited dynamic range; blurring artifacts accompanying drive for increasing sensitivity and/or imaging speed. Despite these limitations, by combining MRI techniques developed for solid and liquid states and using independent information on relaxation properties of water, interacting with the material of interest, true images of distributions of both water, material and molecular properties in a wide range of concentrations can be obtained. Examples of MRI application will be given in the areas of soil and mineral research where understanding water transport and erosion processes is one of the key challenges. Efforts in developing and adapting MRI approaches to study these kinds of systems will be outlined as well. Extensive studies of clay/water interaction have been carried out in order to provide a quantitative

  14. Origin of clay-mineral variation in Wisconsinan age sediments from the Lake Michigan basin

    SciTech Connect

    Monaghan, G.W. ); Larson, G.J. . Dept. of Geological Sciences)

    1994-04-01

    Drift samples collected in Wisconsin and Michigan from exposures representative of the Wisconsinan stratigraphy of the Lake Michigan Lobe indicate that clay mineral and shale lithology systematically vary between successive till sheets as a result of differential erosion of two unique source beds: shale bedrock, rich in 10[angstrom] clay (illite) and pre-existing drift (particularly lacustrine clay), depleted in 10[angstrom] clay. A general increase in relative amounts of 10[angstrom] clay and shale clasts begins with early or middle Wisconsinan (Altonian) Glenn Shores till and continues through late Wisconsinan (Woodfordian) Ganges-New Berlin till and Saugatuck-Oak Creek till. Both 10[angstrom] clay and shale decrease in post Mackinaw (late Woodfordian) Interstade Ozaukee-Haven and Two Rivers tills. Clay minerals in till rich in 10[angstrom] clay (Saugatuck-Oak Creek) were derived mainly from extensive erosion and comminution of shale whereas those in tills depleted in 10[angstrom] clay (Ganges-New Berlin, Ozaukee-Haven, and Two Rivers) were eroded mainly from lacustrine clay. Because it is compositionally dissimilar to either the shale or lake clay source and relatively rich in kaolinite, clay minerals in early-middle Wisconsinan Glenn Shores till may have been derived from Sangamon saprolite eroded during an early post-Sangamon ice advance. Variations in source bed erosion and subsequent changes in till lithology result either from depletion of the source bed (Glenn Shores till) or from progressively eroding drift mantling shale outcrops (unroofing) during successive late Wisconsinan ice advances.

  15. Use of organo-clays in the removal of toxic organics from industrial wastewaters

    SciTech Connect

    Srinivasan, K.R.; Fogler, H.S.

    1987-01-01

    This study describes the development of organo-clays as cost-effective adsorbents for the removal of nonionic, toxic organics from wastewaters. Cetyl pyridinium montmorillonite (CPC-CLAY; an interlayer organo-clay) and Cetyl pyridinium hydroxy aluminum montmorillonite (CPC(HYDAL-CLAY; a predominantly external layer organo-clay) were prepared as model sorbents. Using pentachlorophenol (PCP) as the target organic molecule, our studies show that CPC-HYDAL-CLAY containing 12.0% by weight surface organic carbon is significantly more effective (about 10 times) than CPC-CLAY with 19.2% by weight surface organic carbon. Similar results were obtained with La-CPC-CLAY (12% organic carbon) and CPC-kaolinite (3.0% organic carbon), both of which exhibit surface orientation of organic carbon similar to that of CPC-HYDAL-CLAY. Specifically, the effectiveness of CPC-kaolinite establishes the idea that orientation of surface organic carbon may be as significant as the actual amount. All the three external surface oriented organo-clays studied here are comparable to activated carbon in their sorption potential for PCP. Electrokinetic and adsorption/desorption measurements reveal that in the cases of CPC-HYDAL-CLAY and La-CPC-CLAY, binding of CPC ion to the respective surfaces is of the high affinity and irreversible type and that the endpoint of adsorption may be in the form of a bidimensional aggregate or a ''hemimicelle''.

  16. Mixed Waste Management Facility (MWMF) closure, Savannah River Plant: Clay cap test section construction report

    SciTech Connect

    Not Available

    1988-02-26

    This report contains appendices 3 through 6 for the Clay Cap Test Section Construction Report for the Mixed Waste Management Facility (MWMF) closure at the Savannah River Plant. The Clay Cap Test Program was conducted to evaluate the source, lab. permeability, in-situ permeability, and compaction characteristics, representative of kaolin clays from the Aiken, South Carolina vicinity. (KJD)

  17. Geotechnical evaluation of Turkish clay deposits: a case study in Northern Turkey

    NASA Astrophysics Data System (ADS)

    Kalkan, Ekrem; Bayraktutan, M. Salih

    2008-09-01

    Clay deposits in Oltu-Narman basins (Erzurum, northern Turkey) have been studied to determine their engineering properties and to evaluate their uses for geotechnical applications. These deposits are concentrated in two different stratigraphic horizons namely the Late Oligocene and the Early Miocene sequences. Clay-rich fine-grained sedimentary units are deposited in shallow marine and lagoonar mixed environments. Their clay minerals originated by the alteration of Eocene calc-alkaline island-arc volcanics, preferably from pyroclastics (trachite and andesite flow), which form the basement for the Oltu depression. Smectite group clay minerals are found abundant in clay deposits. The experimental results show that the clay soils have high plasticity behaviors and low hydraulic conductivity properties. The optimum water content, the free swell, and the swelling pressure of clay samples decreased and the maximum dry unit weight of clay samples increased under high temperature. Consequently, it is concluded that the expanding of clay soils is an important soil problem that cannot be avoided in the significant parts of Oltu city and its villages. However, the soils of clay-rich layers in the outcrops-section of clay deposits can be successfully used to build compacted clay liners for landfill systems and to construct vertical and horizontal barriers for protection of ground water and for preventing soil pollution in geotechnical applications.

  18. Method for distributing an aqueous solution containing a peroxygen in clay

    SciTech Connect

    Norris, R.D.; Brown, R.A.; Richards, J.C.

    1988-05-31

    A process for distributing a peroxygen through particulate matter containing clay without swelling the clay is described comprising incorporating a compound selected from the group consisting of a salt of a perborate or a persulfate anion into water to form an aqueous solution absent a colloidal agent to impart a high viscosity, and introducing the aqueous solution into the particulate matter containing clay.

  19. A review of WIPP (Waste Isolation Pilot Plant) repository clays and their relationship to clays of adjacent strata

    SciTech Connect

    Krumhansl, J.L.; Kimball, K.M.; Stein, C.L.

    1990-12-01

    The Salado Formation is a thick evaporite sequence located in the Permian Delaware Basin of southeastern New Mexico. This study focuses on the intense diagenetic alteration that has affected the small amounts of clay, feldspar, and quartz washed into the basin during salt deposition. These changes are of more than academic interest since this formation also houses the WIPP (Waste Isolation Pilot Plant). Site characterization concerns warrant compiling a detailed data base describing the clays in and around the facility horizon. An extensive sampling effort was undertaken to address these programmatic issues as well as to provide additional insight regarding diagenetic mechanisms in the Salado. Seventy-five samples were collected from argillaceous partings in halite at the stratigraphic level of the Waste Isolation Pilot Plant (WIPP). These were compared with twenty-eight samples from cores of the Vaca Triste member of the Salado, a thin clastic unit at the top of the McNutt potash zone, and with a clay-rich sample from the lower contact of the Culebra Dolomite (in the overlying Rustler Formation). These settings were compared to assess the influence of differences in brine chemistry (i.e., halite and potash facies, normal to hypersaline marine conditions) and sediment composition (clays, sandy silt, dolomitized limestone) on diagenetic processes. 44 refs., 11 figs., 5 tabs.

  20. Retention and loss of water extractable carbon in soils: effect of clay properties.

    PubMed

    Nguyen, Trung-Ta; Marschner, Petra

    2014-02-01

    Clay sorption is important for organic carbon (C) sequestration in soils, but little is known about the effect of different clay properties on organic C sorption and release. To investigate the effect of clay content and properties on sorption, desorption and loss of water extractable organic C (WEOC), two experiments were conducted. In experiment 1, a loamy sand alone (native) or mixed with clay isolated from a surface or subsoil (78 and 96% clay) resulting in 90, 158 and 175 g clay kg(-1) soil. These soil treatments were leached with different WEOC concentrations, and then CO2 release was measured for 28 days followed by leaching with reverse osmosis water at the end of experiment. The second experiment was conducted to determine WEOC sorption and desorption of clays isolated from the loamy sand (native), surface soil and subsoil. Addition of clays isolated from surface and subsoil to sandy loam increased WEOC sorption and reduced C leaching and cumulative respiration in percentage of total organic C and WEOC added when expressed per g soil and per g clay. Compared to clays isolated from the surface and subsoil, the native clay had higher concentrations of illite and exchangeable Ca(2+), total organic C and a higher CEC but a lower extractable Fe/Al concentration. This indicates that compared to the clay isolated from the surface and the subsoil, the native clay had fewer potential WEOC binding sites because it had lower Fe/Al content thus lower number of binding sites and the existing binding sites are already occupied native organic matter. The results of this study suggest that in the soils used here, the impact of clay on WEOC sorption and loss is dependent on its indigenous organic carbon and Fe and/or Al concentrations whereas clay mineralogy, CEC, exchangeable Ca(2+) and surface area are less important. PMID:24144942

  1. Clay mineralogy of Pleistocene Lake Tecopa, Inyo County, California

    USGS Publications Warehouse

    Starkey, Harry C.; Blackmon, Paul D.

    1979-01-01

    Pleistocene Lake Tecopa in southeastern Inyo County, Calif., was formed when the Amargosa River was blocked at the southern end of its valley. The lake acted as a settling basin for detrital material being transported by the river. This detritus consisted of clays, quartz, feldspars, and micas which became mudstones and siltstones. These mudstones and siltstones, much eroded and dissected after the draining of the lake, extend over the entire basin and are interbedded with tuffs formed by the intermittent deposition of volcanic ashfalls in the former lake waters. These lightcolored mudstones and siltstones are tough and well indurated and break with a conchoidal fracture. The predominant clay mineral in these detrital beds is a lithiumbearing saponite, which is found not only in the lake beds but also in the area beyond the boundaries of the lake, especially in fluvial deposits in the drainage basin of the Amargosa River to the north. This saponite does not contain enough lithium to be classified as a hectorite, and we have observed no indications that this clay consists of a mixture of two phases, such as hectorite and a diluent. Some authigenic dioctahedral montmorillonite, found only in small quantities close to the tuffs, was formed by alteration of the volcanic glass of the tuffs and was then admixed with the overlying or underlying detrital clays. The only authigenic clay-type mineral found in any significant quantity is sepiolite, found near the edges of the lake basin and stratigraphically located mainly within a meter of the two uppermost tuffs. This sepiolite probably was precipitated when silica became available to the magnesium-bearing lake water through dissolution of the volcanic ash. Precipitation of sepiolite probably did not occur within the tuffs owing to the presence of alumina in solution. Zeolites were produced there and sepiolite formed outside the margins of the tuffs. Also formed by the high-pH lake waters were water-soluble minerals, which

  2. Cyclic deformations in the Opalinus clay: a laboratory experiment

    NASA Astrophysics Data System (ADS)

    Huber, Emanuel; Huggenberger, Peter; Möri, Andreas; Meier, Edi

    2015-04-01

    The influence of tunnel climate on deformation cycles of joint openings and closings is often observed immediately after excavation. At the EZ-B niche in the Mt. Terri rock laboratory (Switzerland), a cyclic deformation of the shaly Opalinus clay has been monitored for several years. The deformation cycles of the joints parallel to the clay bedding planes correlate with seasonal variations in relative humidity of the air in the niche. In winter, when the relative humidity is the lowest (down to 65%), the joints open as the clay volume decreases, whereas they tend to close in the summer when the relative humidity reaches up to 100%. Furthermore, in situ measurements have shown the trend of an increasingly smaller aperture of joints with time. A laboratory experiment was carried out to reproduce the observed cyclic deformation in a climate chamber using a core sample of Opalinus clay. The main goal of the experiment was to investigate the influence of the relative humidity on the deformation of the Opalinus clay while excluding the in situ effects (e.g. confining stress). The core sample of Opalinus clay was put into a closed ended PVC tube and the space between the sample and the tube was filled with resin. Then, the sample (size: 28 cm × 14 cm × 6.5 cm) was cut in half lengthways and the open end was cut, so that the half-core sample could move in one direction. The mounted sample was exposed to wetting and drying cycles in a climate chamber. Air temperature, air humidity and sample weight were continuously recorded. Photographs taken at regular time intervals by a webcam allowed the formation/deformation of cracks on the surface of the sample to be monitored. A crackmeter consisting of a double-plate capacitor attached to the core sample was developed to measure the dynamics of the crack opening and closing. Preliminary results show that: - Deformation movements during different climate cycles can be visualized with the webcam - The crackmeter signal gives a

  3. Field trip guidebook on environmental impact of clays along the upper Texas coast

    NASA Technical Reports Server (NTRS)

    Garcia, Theron D.; Ming, Douglas W.; Tuck, Lisa Kay

    1991-01-01

    The field trip was prepared to provide an opportunity to see first hand some the environmental hazards associated with clays in the Houston, Texas area. Because of the very high clay content in area soils and underlying Beaumont Formation clay, Houston is a fitting location to host the Clay Mineral Society. Examinations were made of (1) expansive soils, (2) subsidence and surface faulting, and (3) a landfill located southeast of Houston at the Gulf Coast Waste Disposal Authority where clay is part of the liner material.

  4. Metachromasy as an indicator of photostabilization of methylene blue adsorbed to clays and minerals.

    PubMed

    Samuels, Maya; Mor, Omer; Rytwo, Giora

    2013-04-01

    The influence of methylene blue adsorption to different clays on its photodegradation was studied. Methylene blue in solution was decomposed by sunlight in a zero-order process. Adsorption to some clay minerals (sepiolite and vermiculite) and a zeolite (clinoptilolite) accelerated the degradation process, and converted it to a first-order reaction. On the other hand, adsorption to other clay minerals (palygorskite and montmorillonite) stabilized the dye and prevented its degradation. Interestingly, in the clay-dye complexes that exhibited stability, clear metachromasy of the adsorbed methylene blue occurred, whereas the effect was not observed in the clay-dye complexes that underwent photodegradation. PMID:23474529

  5. Evaluation of the medicinal use of clay minerals as antibacterial agents.

    PubMed

    Williams, Lynda B; Haydel, Shelley E

    2010-07-01

    Natural clays have been used to heal skin infections since the earliest recorded history. Recently our attention was drawn to a clinical use of French green clay (rich in Fe-smectite) for healing Buruli ulcer, a necrotizing fasciitis ('flesh-eating' infection) caused by Mycobacterium ulcerans. These clays and others like them are interesting as they may reveal an antibacterial mechanism that could provide an inexpensive treatment for this and other skin infections, especially in global areas with limited hospitals and medical resources.Microbiological testing of two French green clays, and other clays used traditionally for healing, identified three samples that were effective at killing a broad-spectrum of human pathogens. A clear distinction must be made between 'healing clays' and those we have identified as antibacterial clays. The highly adsorptive properties of many clays may contribute to healing a variety of ailments, although they are not antibacterial. The antibacterial process displayed by the three identified clays is unknown. Therefore, we have investigated the mineralogical and chemical compositions of the antibacterial clays for comparison with non-antibacterial clays in an attempt to elucidate differences that may lead to identification of the antibacterial mechanism(s).The two French green clays used to treat Buruli ulcer, while similar in mineralogy, crystal size, and major element chemistry, have opposite effects on the bacterial populations tested. One clay deposit promoted bacterial growth whereas another killed the bacteria. The reasons for the difference in antibacterial properties thus far show that the bactericidal mechanism is not physical (e.g., an attraction between clay and bacteria), but by a chemical transfer or reaction. The chemical variables are still under investigation.Cation exchange experiments showed that the antibacterial component of the clay can be removed, implicating exchangeable cations in the antibacterial process

  6. Mechanisms of clay smear formation in 3D - a field study

    NASA Astrophysics Data System (ADS)

    Kettermann, Michael; Tronberens, Sebastian; Urai, Janos; Asmus, Sven

    2016-04-01

    Clay smears in sedimentary basins are important factors defining the sealing properties of faults. However, as clay smears are highly complex 3D structures, processes involved in the formation and deformation of clay smears are not well identified and understood. To enhance the prediction of sealing properties of clay smears extensive studies of these structures are necessary including the 3D information. We present extraordinary outcrop data from an open cast lignite mine (Hambach) in the Lower Rhine Embayment, Germany. The faults formed at a depth of 150 m, and have Shale Gouge Ratios between 0.1 and 0.3. Material in the fault zones is layered, with sheared sand, sheared clay and tectonically mixed sand-clay gouge. We studied the 3D thickness distribution of clay smear from a series of thin-spaced incremental cross-sections and several cross-sections in larger distances along the fault. Additionally, we excavated two large clay smear surfaces. Our observations show that clay smears are strongly affected by R- and R'-shears, mostly at the footwall side of our outcrops. These shears can locally cross and offset clay smears, forming holes. Thinnest parts of the clay smears are often located close to source layer cutoffs. Investigating the 3D thickness of the clay smears shows a heterogeneous distribution, rather than a continuous thinning of the smear with increasing distance to the source layers. We found two types of layered clay smears: one with continuous sheared sand between two clay smears providing vertical pathways for fluid flow, and one which consists of overlapping clay patches separated by sheared sand that provide a tortuous pathway across the clay smear. On smaller scale we identified grain-scale mixing as an important process for the formation of clay smears. Sand can be entrained into the clay smear by mixing from the surrounding host rock as well as due to intense shearing of sand lenses that were incorporated into the smear. This causes clay smears

  7. Using the Complete Nano Engineering Geological Spectrum to Assess the Performance of Clay Barriers

    NASA Astrophysics Data System (ADS)

    Schmitz, Robrecht M.; Schroeder, Christian; Thorez, Jacques; Charlier, Robert

    Clays are geomaterials used in various (over 100) applications in our society. The more common geotechnical applications are clay barriers to contain waste, slurry walls etc. But even if clays are not used as construction material, the engineering geologist encounters them frequently during construction of e.g. foundations and tunnels. As clays are end products of the weathering of silicate geomaterials they are stable as such, but within this group of clay minerals, geotechnical properties vary enormously. Some of these variations are due to chemo-plasticity e.g. reflected in the effect of the composition of the pore fluid on the mechanical properties of clay. One approach to deal with these chemo plastic effects is to separate them according to the scale or level on which they are acting. In clays one can discern the level of the clay silicate sheets (TOT or TO), the clay interlayer level and the clay particles level. This contribution aims to show how an analysis of the processes on these three levels can help to assess the geotechnical properties of clays in contact with various fluids.

  8. Probing Contaminant Transport to and from Clay Surfaces in Organic Solvents and Water Using Solution Calorimetry.

    PubMed

    Pourmohammadbagher, Amin; Shaw, John M

    2015-09-15

    Clays, in tailings, are a significant ongoing environmental concern in the mining and oilsands production industries, and clay rehabilitation following contamination poses challenges episodically. Understanding the fundamentals of clay behavior can lead to better environmental impact mitigation strategies. Systematic calorimetric measurements are shown to provide a framework for parsing the synergistic and antagonistic impacts of trace (i.e., parts per million level) components on the surface compositions of clays. The enthalpy of solution of as-received and "contaminated" clays, in as-received and "contaminated" organic solvents and water, at 60 °C and atmospheric pressure, provides important illustrative examples. Clay contamination included pre-saturation of clays with water and organic liquids. Solvent contamination included the addition of trace water to organic solvents and trace organic liquids to water. Enthalpy of solution outcomes are interpreted using a quantitative mass and energy balance modeling framework that isolates terms for solvent and trace contaminant sorption/desorption and surface energy effects. Underlying surface energies are shown to dominate the energetics of the solvent-clay interaction, and organic liquids as solvents or as trace contaminants are shown to displace water from as-received clay surfaces. This approach can be readily extended to include pH, salts, or other effects and is expected to provide mechanistic and quantitative insights underlying the stability of clays in tailings ponds and the behaviors of clays in diverse industrial and natural environments. PMID:26296102

  9. Zinc-rich clays in supergene non-sulfide zinc deposits

    NASA Astrophysics Data System (ADS)

    Choulet, F.; Buatier, M.; Barbanson, L.; Guégan, R.; Ennaciri, A.

    2016-04-01

    The nature and the origin of zinc clays are poorly understood. With the example of the Bou Arhous Zn-Pb ore deposit in the Moroccan High Atlas, this study presents new data for the mineralogical and chemical characterization of barren and zinc clays associated with non-sulfide zinc ores. In the field, white to ocher granular clays are associated with willemite (Zn2SiO4), while red clays fill karst-related cavities cutting across the non-sulfide ore bodies. Red clays (kaolinite, chlorite, illite, and smectite) present evidence of stratification that reflects internal sedimentation processes during the karst evolution. White clays contain 7-Å clay mineral/smectite irregular interstratified minerals with less than 20 % of smectite layers. Willemite is partially dissolved and is surrounded by authigenic zinc clay minerals. Together with XRD results, WDS analyses on newly formed clay aggregates suggest that this interstratified mineral is composed of fraipontite and sauconite. CEC measurements support that zinc is only located within the octahedral sheets. These new results support the following process: (i) dissolution of willemite, leading to release of Si and Zn, (ii) interaction between Zn-Si-rich solutions and residual-detrital clays, and (iii) dissolution of kaolinite and formation of interstratified zinc clay minerals that grew over detrital micas.

  10. Morphology and thermal properties of clay/PMMA nanocomposites obtained by miniemulsion polymerization.

    PubMed

    García-Chávez, Karla I; Hernández-Escobar, Claudia A; Flores-Gallardo, Sergio G; Soriano-Corral, Florentino; Saucedo-Salazar, Esmeralda; Zaragoza-Contreras, E Armando

    2013-06-01

    Miniemulsion polymerization was used as the synthetic method to produce clay/poly(methyl methacrylate) nanocomposites. Two kinds of interfacial interactions clay-polymer particle were observed by electron microscopy, one where the polymer particles are adhered on the surface of the larger fragments of clay, and another where nanometric fragments of clay are encapsulated by polymer particles. Variations in the glass transition temperature (T(g)) and thermomechanical properties of the matrix, as function of clay content, were observed. In particular, at the highest clay loading (1.0 wt%) depression of T(g) and thermomechanical properties were observed. The increased clay-polymer matrix interfacial area appears to be the conditioning factor that determines such behavior. PMID:23541871

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

    PubMed Central

    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. PMID:25734235

  12. Evaluation of correlation between physical properties and ultrasonic pulse velocity of fired clay samples.

    PubMed

    Özkan, İlker; Yayla, Zeliha

    2016-03-01

    The aim of this study is to establish a correlation between physical properties and ultrasonic pulse velocity of clay samples fired at elevated temperatures. Brick-making clay and pottery clay were studied for this purpose. The physical properties of clay samples were assessed after firing pressed clay samples separately at temperatures of 850, 900, 950, 1000, 1050 and 1100 °C. A commercial ultrasonic testing instrument (Proceq Pundit Lab) was used to evaluate the ultrasonic pulse velocity measurements for each fired clay sample as a function of temperature. It was observed that there became a relationship between physical properties and ultrasonic pulse velocities of the samples. The results showed that in consequence of increasing densification of the samples, the differences between the ultrasonic pulse velocities were higher with increasing temperature. These findings may facilitate the use of ultrasonic pulse velocity for the estimation of physical properties of fired clay samples. PMID:26725032

  13. Development of an unbonded capping system for clay masonry prisms

    SciTech Connect

    Crouch, L.K.; Henderson, R.C.; Sneed, W.A. Jr.

    1999-07-01

    To ascertain if an unbonded capping system was feasible for clay masonry prisms, the compressive strengths of thirty clay masonry prisms capped with an unbonded capping system modeled after ASTM C 1231 were compared with those of thirty masonry prisms capped with ASTM C 67 approved high-strength gypsum cement at the ages of 7 and 28 days. All prisms were constructed by a professional mason using Grade SW, Type FBS cored face brick from the same lot and ASTM C 270 Type S PC-lime mortar. There was no significant difference in mean compressive strength for the two capping methods at either age. In addition, capping with the unbonded capping system was faster and easier. Further, 28-day results obtained using the unbonded capping system had a lower coefficient of variation and higher mean compressive strength than those obtained with high-strength gypsum.

  14. Flow in aquifers with clay laminae: 1. The comprehensive potential

    NASA Astrophysics Data System (ADS)

    Strack, O. D. L.

    1981-08-01

    A description is given of steady flow in a system of homogeneously permeable aquifers that are separated by thin impervious clay laminae. Restriction is made to laminae that do not overlap one another. A steady state two-dimensional Dupuit-Forchheimer model is formulated to predict piezometric heads in the aquifers. The flow below the laminae may be confined or unconfined, and the possible occurrence of perched conditions above the laminae is taken into account. A new potential is introduced, with a gradient equal to minus the vectorial sum of the discharges in the upper and lower aquifers. This potential is referred to as the comprehensive potential and is determined by solving a boundary value problem of the Poisson equation. Application of the comprehensive potential makes it possible to establish heads along the edges of the clay laminae without the use of an iterative procedure. Two flow problems are solved as examples of the technique presented in this paper.

  15. Optimal Design of Sheet Pile Wall Embedded in Clay

    NASA Astrophysics Data System (ADS)

    Das, Manas Ranjan; Das, Sarat Kumar

    2015-09-01

    Sheet pile wall is a type of flexible earth retaining structure used in waterfront offshore structures, river protection work and temporary supports in foundations and excavations. Economy is an essential part of a good engineering design and needs to be considered explicitly in obtaining an optimum section. By considering appropriate embedment depth and sheet pile section it may be possible to achieve better economy. This paper describes optimum design of both cantilever and anchored sheet pile wall penetrating clay using a simple optimization tool Microsoft Excel ® Solver. The detail methodology and its application with examples are presented for cantilever and anchored sheet piles. The effects of soil properties, depth of penetration and variation of ground water table on the optimum design are also discussed. Such a study will help professional while designing the sheet pile wall penetrating clay.

  16. The Fluid Memory of Clays in Faults and Folds

    NASA Astrophysics Data System (ADS)

    van der Pluijm, B.; Fitz-Diaz, E.; Haines, S. H.

    2013-12-01

    Constraining fluid sources is key to understanding crustal-scale fluid circulation, rock mechanics, mineral reactions and the origin of economic deposits. The role of meteoric fluids in exhumed fault rocks has been proposed in a few recent studies, notably in mylonites in low-angle normal fault (LANF) systems. However, the extent of meteoric influx and fluid pathways, and a mechanism for infiltration of surface waters up to 10+km depth remains mostly unknown. The occurrence of clay neomineralization in fault rocks and folds has the potential to resolve this question, as clay (trans)formation preserves host fluid information in its isotopic signatures, particularly H. New stable isotope studies of clays in normal faults and folds in the SW US and Mexico show major meteoric input, based on which we propose a mechanism for downward fluid infiltration and upper-crustal circulation. We obtained paired δ18O and δ2H (‰ wrt SMOW) isotopic measurements from neo-formed clays in fault gouge that formed above major LANF detachments in the SW US, which show that clays in brittle fault rocks formed from exchange with pristine to only weakly evolved meteoric fluids. Illite δ18O measurements range from -2.0‰ to +11.5‰, while illite δ2H measurements range from -142‰ to -107‰. Smectite δ18O values are +3.6‰ to 17.9‰, while smectite δ2H measurements are -147‰ to -95‰. The isotopic signature of clays at multiple depths in LANFs indicates that crustal-scale normal fault systems are highly permeable over geologic time scales, and that they are dominated by downward fluid flow of surface waters, instead of buoyancy-driven flow from deeper levels. Clay grain size fractions from folded rocks of the Mexican fold-thrust belt containing chlorite and smectite show very low values in δ2H (-75.9 to -53.9‰), while samples containing illite and kaolinite or pure illite show slightly higher δ2H values (-33.1 to -50.1‰). In these samples the discriminating potential of

  17. Electric alignment of plate shaped clay aggregates in oils

    NASA Astrophysics Data System (ADS)

    Castberg, Rene; Rozynek, Zbigniew; Måløy, Knut Jørgen; Flekkøy, Eirik

    2016-01-01

    We experimentally investigate the rotation of plate shaped aggregates of clay mineral particles immersed in silicone oil. The rotation is induced by an external electric field. The rotation time is measured as a function of the following parameters: electric field strength, the plate geometry (length and width) and the dielectric properties of the plates. We find that the plates always align with their longest axis parallel to the direction of the electric field (E), independently of the arrangement of individual clay ‑2 mineral particles within the plate. The rotation time is found to scale as E and is proportional to the viscosity (μ), which coincides well with a model that describes orientation of dipoles in electric fields. As the length of the plate is increased we quantify a difference between the longitudinal and transverse polarisability. Finally, we show that moist plates align faster. We attribute this to the change of the dielectric properties of the plate due to the presence of water.

  18. Diffusion of radionuclides in clay-based ceramics

    SciTech Connect

    Ivanov, P.A.; Gulin, A.N.; Shatkov, V.M.; Shashukov, E.A.; Kuznetsov, B.S.

    1988-09-01

    The diffusion coefficients of sodium-22, strontium-90, and cesium-134 in clay-containing ceramics of three types are determined by the method of integral residual activity. It is found that at the investigated temperatures the diffusion coefficients of the radionuclides decrease in the order sodium-22, cesium-134, strontium-90. Migration of cesium-134 in comparison with sodium-22 is characterized by substantially lower values of the preexponential factor and diffusion activation energy. It is shown that in the case of ceramic made up of 89% by mass cambrian clay and 11% by mass perlite, increase in relative moisture content of the samples from0.05 to 0.3% leads to substantial (by 2-3 orders of magnitude) growth of the diffusion coefficients of the radionuclides. Further increase in the relative moisture content has practically no effect on their diffusive mobility.

  19. Clay-Shoveler Fracture in a Paddler: A Case Report.

    PubMed

    Olivier, Etienne Cornelis; Muller, Elouise; Janse van Rensburg, Dina Christina

    2016-05-01

    Clay-shoveler fracture is a fracture of the spinous process of lower cervical and upper thoracic vertebrae. It has only rarely been reported as being caused by an overuse sports injury. This case report describes the first reported clay-shoveler fracture in a paddler. A 51-year-old male paddler, preparing for a paddling adventure over 630 km, felt a click and a sharp pain paravertebrally on the level of the upper thoracic vertebrae while paddling. Sonar investigation did not reveal any muscular injury but computed tomography revealed a fracture of the spinous process of T1. In this case, it is a stress injury due to excessive paddling over a short period of time. This fracture causes debilitating pain in the acute phase and is mainly treated conservatively. PMID:26247546

  20. The crystallization of new synthetic organo-clays

    SciTech Connect

    Carrado, K.A.

    1994-03-01

    A novel method for the preparation of new synthetic, potentially catalytic clays has been discovered. In this method, a diverse variety of organic and-organometallic molecules can be directly incorporated during crystallization of the clay. This method has great potential for the incorporation of catalytically active species to create new heterogeneous catalysts. The catalyst precursors are organic-inorganic composites comprised of a layered silicate intercalated with such molecules as porphyrins or metalloporphyrins, organic aromatic dyes, a Cu(II) phthalocyanine dye, or bulky transition metal chelates. This procedure is readily applicable for introducing specific molecules for highly tailored applications, because successful templates include a variety of catalytically, electrochemically, and photochemically active species. Characterization studies were performed to establish the composition of the synthetic products, including x-ray absorption spectroscopy at NSLS.

  1. On sorption and swelling of CO2 in clays

    DOE PAGESBeta

    Busch, A.; Bertier, P.; Gensterblum, Y.; Rother, G.; Spiers, C. J.; Zhang, M.; Wentinck, H. M.

    2016-03-23

    One well-studied technology is the geological storage of carbon dioxide (CO2), and a number of demonstration projects around the world have proven its feasibility and challenges. Storage conformance and seal integrity are among the most important aspects, as they determine risk of leakage as well as limits for storage capacity and injectivity. By providing evidence for safe storage is critical for improving public acceptance. Most caprocks are composed of clays as dominant mineral type which can typically be illite, kaolinite, chlorite or smectite. A number of recent studies addressed the interaction between CO2 and these different clays and it wasmore » shown that clay minerals adsorb considerable quantities of CO2. For smectite this uptake can lead to volumetric expansion followed by the generation of swelling pressures. On the one hand CO2 adsorption traps CO2, on the other hand swelling pressures can potentially change local stress regimes and in unfavourable situations shear-type failure is assumed to occur. Moreover, for storage in a reservoir having high clay contents the CO2 uptake can add to storage capacity which is widely underestimated so far. Smectite-rich seals in direct contact with a dry CO2 plume at the interface to the reservoir might dehydrate leading to dehydration cracks. Such dehydration cracks can provide pathways for CO2 ingress and further accelerate dewatering and penetration of the seal by supercritical CO2. At the same time, swelling may also lead to the closure of fractures or the reduction of fracture apertures, thereby improving seal integrity. Finally, the goal of this communication is to theoretically evaluate and discuss these scenarios in greater detail in terms of phenomenological mechanisms, but also in terms of potential risks or benefits for carbon storage.« less

  2. Geostatistical analysis of field hydraulic conductivity in compacted clay

    SciTech Connect

    Rogowski, A.S.; Simmons, D.E.

    1988-05-01

    Hydraulic conductivity (K) of fractured or porous materials is associated intimately with water flow and chemical transport. Basic concepts imply uniform flux through a homogeneous cross-sectional area. If flow were to occur only through part of the area, actual rates could be considerably different. Because laboratory values of K in compacted clays seldom agree with field estimates, questions arise as to what the true values of K are and how they should be estimated. Hydraulic conductivity values were measured on a 10 x 25 m elevated bridge-like platform. A constant water level was maintained for 1 yr over a 0.3-m thick layer of compacted clay, and inflow and outflow rates were monitored using 10 x 25 grids of 0.3-m diameter infiltration rings and outflow drains subtending approximately 1 x 1 m blocks of compacted clay. Variography of inflow and outflow data established relationships between cores and blocks of clay, respectively. Because distributions of outflow rates were much less and bore little resemblance to the distributions of break-through rates based on tracer studies, presence of macropores and preferential flow through the macropores was suspected. Subsequently, probability kriging was applied to reevaluate distribution of flux rates and possible location of macropores. Sites exceeding a threshold outflow of 100 x 10/sup -9/ m/s were classified as outliers and were assumed to probably contain a significant population of macropores. Different sampling schemes were examined. Variogram analysis of outflows with and without outliers suggested adequacy of sampling the site at 50 randomly chosen locations. Because of the potential contribution of macropores to pollutant transport and the practical necessity of extrapolating small plot values to larger areas, conditional simulations with and without outliers were carried out.

  3. New techniques for clay mineral identification by remote sensing

    SciTech Connect

    Abrams, M.J.; Goetz, A.F.H.; Lang, H.

    1983-03-01

    In the past three years there have been major advancements in our ability to identify clay minerals by remote sensing. Multispectral scanners, including NASA's Thematic Mapper Simulator (analog for Landsat-D Thematic Mapper) have had several broad-band channels in the wavelength region of 1.0 to 2.5 ..mu..m. In particular, the wavelength region 2.0 to 2.5 ..mu..m contains diagnostic spectral-absorption features for most layered silicates. Computer processing of image data obtained with these scanners has allowed the identification of the presence of clay minerals, without, however, being able to identify specific mineralogies. Studies of areas with known hydrocarbon deposits and porphyry copper deposits have demonstrated the value of this information for rock-type discrimination and recognition of hydrothermal alteration zones. Non-imaging, narrow-band radiometers and spectrometers have been used in the field, from aircraft, and from space to identify individual mineralogical constituents. This can be done because of diagnostic spectral absorption features in the 2.0 to 2.5 ..mu..m region characteristic of different clay types. Preliminary analysis of SMIRR data over Egypt showed that kaolinite, carbonate rocks, and possibly montmorillonite, could be identified directly. Plans are currently under way for development of narrow-band imaging systems which will be capable of producing maps showing the surface distribution of individual clay types. This will represent a major step in remote sensing, by allowing unique identification of minerals rather than the current ability only to discriminate among materials. Applications of this technology will provide geologists with a powerful new tool for resource exploration and general geologic mapping problems.

  4. Geochemical dynamics of cesium sorption by selected clay minerals

    SciTech Connect

    Noll, M.R.

    1989-01-01

    This study focuses on the interactions of cesium with selected clay minerals. Cesium is of interest as it is a chief component of high level radioactive waste. Primarily, the thermodynamics and kinetics of Cs exchange reactions were investigated to determine the preference for Cs of a kaolinite, illite, and vermiculite. Thermodynamic studies indicated that Cs was most strongly preferred by Ca saturated clays. Of the three minerals studied, illite proved to be the most effective in adsorbing Cs as indicated by the Vanselow Selectivity Coefficients (k{sub v}). The k{sub v} values for illite ranged from 5.87 to over 10{sup 10}, depending on the mineral and saturating cation. Kinetics experiments proved to be the most interesting. On 2:1 clay minerals (illite and vermiculite), two simultaneous reactions are postulated. The first, and faster of the two reactions, is believed to correspond to Cs adsorption on surface planar sites. The second reaction may be the adsorption of Cs on interlayer and wedge exchange sites. Kaolinite only shows a single reaction since it is a 1:1 clay mineral. Rate coefficients were calculated and the first reaction was found to be on the order of one magnitude greater than the second reaction. The reactions on kaolinite were similar to this faster reaction. Desorption data indicated that the rate of desorption was one or more orders of magnitude less than the corresponding adsorption rate. It is important to note, however, that studies on the effect of temperature indicated that Arrhenius behavior is not followed in many of these experiments. It is postulated that changes in cation radius ratio, or the availability of exchange sites is causing this Anti-Arrhenius behavior. Finally, it is concluded that illite exhibits the greatest preference for the adsorption of Cs.

  5. Experimental Support for a Predictive Osmotic Model of Clay Membranes

    SciTech Connect

    Fritz, S.J.

    2001-08-29

    Osmosis has been cited as a mechanism for explaining anomalously high fluid pressures in the subsurface. Clays and shales act as membranes, and osmotic flux across these units may result in pressures sufficiently high to explain these anomalies. The theoretical osmotic pressures as calculated solely from solution properties can be quite large; however, it is not yet resolved whether these geologic membranes are sufficiently ideal to generate such pressures.

  6. First principles characterization of silicate sites in clay surfaces.

    PubMed

    Alvim, Raphael S; Miranda, Caetano R

    2015-02-21

    Aluminosilicate clays like Montmorillonite (MMT) and Muscovite Mica (MT) have siloxane cavities on the basal plane. The hydroxyl groups localized in these cavities and van der Waals (vdW) forces contribute significantly to adsorption processes. However, the basal sites are found to be difficult to characterize experimentally. Here, (001) surfaces of MMT and MT clays were investigated using first-principles calculations to understand how these silicate surface sites are influenced by hydroxyl groups and the effective role of inner layer vdW interactions. Based on density-functional theory (DFT) within the generalized gradient approximation (GGA), different types of exchange-correlation functionals were tested to check the effect of vdW dispersion correction. Noncontact atomic force microscopy (nc-AFM), X-ray absorption spectroscopy (XAS) in the near-edge region and solid-state nuclear magnetic resonance (SS-NMR) spectroscopy were simulated. In both clays, the oxygen surface sites are directly affected by the intralayer interaction through hydroxyl groups. Our results indicated that the chemical environment of the hydroxyl groups is distinct in the MMT and MT structures. The vdW correction was essential for a better description of the surface oxygen sites and correctly describes the similarity between both clays. Particularly, the bulk apical oxygen sites in the MT structure are less influenced by vdW interaction. Compared to MMT, the silicon surface sites of MT are more sensitive to the intralayer changes in Si-Oapical-Al and with less effect of the hydroxyl groups. These results provide a clear understanding of influence of the siloxane cavity on the oxygen and silicon surface sites in aluminosilicates. PMID:25592132

  7. Diffusion of inorganic chemical wastes in compacted clay

    SciTech Connect

    Shackelford, C.D.

    1988-01-01

    The factors that were investigated included the water content/dry unit weight, the method of compaction, the mineralogy of the soil, and the concentration of the ions. The effective diffusion coefficients (D{asterisk}) of three anions (Cl{sup {minus}}, Br{sup {minus}}, and I{sup {minus}}) and three cations (K{sup +}, Cd{sup 2+}, and Zn{sup 2+}) in a simulated waste leachate were measured. Two clay soils (kaolinite and Lufkin clay) and a sand were used in the study. The clay samples were compacted and pre-soaked to minimize hydraulic gradients due to negative pore pressures. Mass balance calculations were performed to indicate possible sinks/sources in the diffusion system. The results of the diffusion tests were analyzed using two analytical solutions to Fick's second law and a commercially available semi-analytical solution. The D{asterisk} values for tests using high-concentration (0.04 N) leachate generally fell in the narrow range of about 4.0 {times} 10{sup {minus}6} to 2.0 {times} 10{sup {minus}5} cm{sup 2}/s, and were relatively insensitive to compaction water content/dry unit weight and to compaction method. The variability in the results from the tests with low-concentration (0.013 N) leachate precluded any definite conclusions from these tests. The values of D{asterisk} measured in this study were compared to values from previous studies, and the D{asterisk} values from this study were found to be slightly conservative (i.e., high). However, the results of the tests may be affected by several chemical and physical factors, and care should be taken to ensure that the soils used in the tests are representative of those used in the application of the test results. Recommendations are made for estimating D{asterisk} values for use in the design of compacted clay barriers for the containment of inorganic chemical wastes.

  8. Electrokinetics of natural and mechanically modified ripidolite and beidellite clays

    SciTech Connect

    Sondi, I.; Pravdic, V.

    1996-08-10

    Particles of clay minerals were studied due to their importance in geochemical processes in natural waters, such as adsorption and transfer of ionic contaminants, stabilization by organics, and flocculation and sedimentation phenomena. Information on the behavior of clays was sought by experiments with model systems. Measurements of electrophoretic mobilities in relation to pH, at varying concentrations of well-characterized fulvic acid (FA), were performed on two structurally well defined, representative clay minerals prepared with clean surfaces: ripidolite (a well-known trioctahedral nonswelling chlorite) and beidellite (a typical dioctahedral smectite). Natural ripidolite and beidellite show high negative electrokinetic potentials in the range pH 2 ({minus}10 and {minus}20 mV, respectively) to pH 10 ({minus}60 and {minus}50 mV, respectively). Experiments utilizing mechanical particle disintegration (dry milling), mimicking natural wear and physical weathering, resulted in increases of specific surface area (12.3 and 1.5 times, respectively) and of cation exchange capacity (3.2 and 1.2 times, respectively). Such small-sized particles, shown by SEM figures, retain their crystal structure (X ray) and the nature of their structural bonds (FTIR), exhibiting an IEP (at pH 6.0 and 3.0, respectively). This was interpreted to be the creation of positively charged edge surfaces. Exposed to fulvic acid in solutions of 10{sup {minus}3} NaCl at pH = 6.5, these new surfaces showed an increase in negative {zeta}-potential for ripidolite, and, to a smaller extent, for beidellite. In the interaction of clay mineral particles with aqueous medium, it is concluded that the degree of mechanical wear is more decisive than the type of the mineral.

  9. Contact metamorphism of clay minerals in central Utah

    SciTech Connect

    Tannenbaum, T.G. . Geology Dept.)

    1993-03-01

    Smectite is the dominant alteration product identified in the contact aureole of a limey shale from the Carmel Formation. The Jurassic-aged shale from Emery County, Utah was intruded by Tertiary basaltic dikes and sills. Samples of the shale were taken in the contact zone and at increasing distances from the country rock-dike contact. Samples of the dike itself were taken from the chill margin, an intermediate zone, and from the center of the intrusion. The clay minerals in the country rock were studied using X-ray diffraction and whole rock analysis of the shale and dike rocks were done by X-ray fluorescence spectrometry. Discrete smectite and illite were identified in the shale at the country rock-dike contact. As the distance from the dike increases, the clay mineral assemblage changes to a mixture of illite and interstratified chlorite/smectite. The proportion of smectite in the clay mineral assemblage correlates with the distance from the dike contact. These data suggest that either a transformation of chlorite/smectite to discrete smectite occurred in proximity to the dike or that fluids associated with the dike promoted smectite formation. Chemical analyses of the whole rock samples reveal no change in bulk composition for the suite of country rock samples. Chemical analyses of the dike rocks, however reveal that calcium contents decrease toward the chill margin, indicating a chemical flux between the dike and surrounding country rocks. The transformation of chlorite/smectite to discrete smectite in the shale and the calcium decrease in the dike rock indicates that a geochemical relationship exists between the dike and country rock. The exact reaction path is not clear yet, but it is evident that intrusion of the small dikes in this area had a profound effect on the clay mineralogy of the surrounding country rocks.

  10. Clay Minerals in Playas of the Mojave Desert, California.

    PubMed

    Droste, J B

    1959-07-10

    Montmorillonite, illite, chlorite, and kaolinite in the playas of southern California are traceable directly to the source areas surrounding the basins. No evidence found in this investigation suggests that these clay minerals are unstable in the sodic or calcic saline lake environment, but this conclusion may not be directly applied to marine evaporite facies where the minerals are rich in potassium and magnesium. PMID:17738603

  11. A hollow clay tile wall seismic performance program overview

    SciTech Connect

    Beavers, J.E.; Jones, W.D.; Stoddart, W.C.T.

    1992-02-25

    An overview of a multiyear hollow clay tile wall (HCTW) program being conducted by Martin Marietta Energy Systems, Inc., at the Oak Ridge Y-12 Plant, for the US Department of Energy is presented. The purpose of the HCTW program is to determine the load capacity of unreinforced infilled HCTW buildings when subjected to earthquakes. Progress to date tends to indicate that extensive retrofit of such structures may not be warranted in low-to-moderate seismic zones.

  12. Rheological study of clay-kaolin aqueous suspensions

    NASA Technical Reports Server (NTRS)

    Lapasin, R.; Lucchini, F.

    1984-01-01

    Rheological characteristics of clay-kaolin aqueous suspensions were studied by a rotational viscometer to correlate their behavior with the properties of ceramic slips for casting containing quartz, feldspars, and other nonplastic materials. In particular, the effects of the different amounts of dry materials and deflocculant (mixture 1:1 of Na2CO3 and Na2SiO3) and of temperatures on the shear-time-dependent properties of suspensions were examined.

  13. Evaluation of the medicinal use of clay minerals as antibacterial agents

    PubMed Central

    Williams, Lynda B.; Haydel, Shelley E.

    2010-01-01

    Natural clays have been used to heal skin infections since the earliest recorded history. Recently our attention was drawn to a clinical use of French green clay (rich in Fe-smectite) for healing Buruli ulcer, a necrotizing fasciitis (‘flesh-eating’ infection) caused by Mycobacterium ulcerans. These clays and others like them are interesting as they may reveal an antibacterial mechanism that could provide an inexpensive treatment for this and other skin infections, especially in global areas with limited hospitals and medical resources. Microbiological testing of two French green clays, and other clays used traditionally for healing, identified three samples that were effective at killing a broad-spectrum of human pathogens. A clear distinction must be made between ‘healing clays’ and those we have identified as antibacterial clays. The highly adsorptive properties of many clays may contribute to healing a variety of ailments, although they are not antibacterial. The antibacterial process displayed by the three identified clays is unknown. Therefore, we have investigated the mineralogical and chemical compositions of the antibacterial clays for comparison with non-antibacterial clays in an attempt to elucidate differences that may lead to identification of the antibacterial mechanism(s). The two French green clays used to treat Buruli ulcer, while similar in mineralogy, crystal size, and major element chemistry, have opposite effects on the bacterial populations tested. One clay deposit promoted bacterial growth whereas another killed the bacteria. The reasons for the difference in antibacterial properties thus far show that the bactericidal mechanism is not physical (e.g., an attraction between clay and bacteria), but by a chemical transfer or reaction. The chemical variables are still under investigation. Cation exchange experiments showed that the antibacterial component of the clay can be removed, implicating exchangeable cations in the antibacterial

  14. Experimental Study of Clay Deposition and Storage in Sandy River Beds

    NASA Astrophysics Data System (ADS)

    Wysocki, N.; Hajek, E. A.

    2014-12-01

    Ancient fluvial deposits are important records of historical surface conditions on Earth and also serve as important reservoir units for groundwater and hydrocarbons. Grain-size heterogeneity within fluvial deposits may record paleo-flow variability and/or paleo-sediment supply, but without improved understanding of the conditions under which clay can accumulate in sandy river beds, it is difficult to uniquely interpret these deposits. In order to better understand the processes controlling when and where fine sediment accumulates in sandy river beds, we conducted a series of physical experiments to test if there is a relationship between supplied clay concentration and the amount of clay preserved in the river bed under constant and variable discharge conditions. In a 15.5 m feed-style flume, water discharge of 0.21 m3/s and sand supply of 15 g/s were used to aggrade a sandy bed 6.5 cm over the course of 4 hours. In three constant-discharge experiments, clay was added in concentrations of 1000 mg/l, 4000 mg/l and 8500 mg/l. An additional experiment with 1000 mg/l clay concentration was conducted with variable water-discharge, where discharge was slowed to a stop every hour of run time and clay allowed to settle for one hour and once overnight. After each experiment, clay deposits observable in the bed were mapped and samples were collected from the dry bed and analyzed for clay content. Results demonstrate that under constant discharge conditions, clay can accumulate in the bed and that the amount of clay retained in the bed is related to the amount of clay supplied to the flume. In sediment deposited with a low clay concentration, little to no clay accumulated in the bed while under high clay concentration, as much five percent of the bed had a high clay fraction. Clay accumulations that formed under constant flow conditions had different distribution and character from those formed under variable discharge conditions. In all experiments, clay retention was

  15. Nanocomposites of irradiated polypropylene with clay are degradable?

    NASA Astrophysics Data System (ADS)

    Komatsu, L. G. H.; Oliani, W. L.; Lugao, A. B.; Parra, D. F.

    2016-01-01

    In nowadays, polypropylene (PP) based nanocomposites containing organically modified montmorillonite (MMT), have gained great attention in the automobilistic industries, construction, paints, packageing, plastic components of the telecommunication industries. The HMSPP (high melt strength polypropylene) is a polypropylene modified by irradiation process, under acetylene atmosphere, in which irradiation occurs in 60Co gamma source. However, when those materials are submitted to environmental ageing nanocomposites demonstrated high decomposition level after 1 year. This fact can be due to presence the metallic ions present in the montmorillonite. The HMS-PP and the Cloisite 20A (MMT) were mixed in twin-screw extruder using maleic anhydride as compatibilizer. In this work two formulations of nanocomposites at 0.1 and 5 wt% of clay were submitted to the environmental and thermal ageing to analyze the effects of degradation on the HMSPP nanocomposites. The evaluation of thermal properties was analyzed by Differential Scanning Calorimetry (DSC) and the chemical alterations were investigated by Carbonyl Index (CI), through Fourier Transformed Infrared (FTIR) technique. The basal distance was measured by X-ray diffraction (DRX) and the clay elements were analyzed by X-ray Fluorescence (WDXRF). The aim of this work was to understand the effects of degradation of the HMS-PP/clay nanocomposites.

  16. Performance evaluation of indirect evaporative cooler using clay pot

    NASA Astrophysics Data System (ADS)

    Ramkumar, R.; Ragupathy, A.

    2016-05-01

    The aim of the experimental study is to investigate the performance of indirect evaporator cooler in hot and humid regions. A novel approach is implemented in the cooler using clay pot with different position (single, double and three pots) and different orientation as aligned and staggered position for potential and feasibility study. The clay pot is the ceramic material where the water filled inside the pot and due to the property of porosity, the water comes outer surface of the pot and contact with the air passing over the pot surface and air get cooled. A test rig was designed and fabricated to collect experimental data. The clay pots were arranged in aligned and staggered position. In our study heat transfer was analysed with various air velocity of 1m/s to 5m/s. The air temperature, relative humidity, pressure drop and effectiveness were measured and the performance of the evaporative cooler was evaluated. The analysis of the data indicated that cooling effectiveness improve with decrease of air velocity at staggered position. It was shown that staggered position has the higher performance (57%) at 1 m/s air velocity comparison with aligned position values at three pots position.

  17. Vegetable Oil-Based Hyperbranched Thermosetting Polyurethane/Clay Nanocomposites

    PubMed Central

    2009-01-01

    The highly branched polyurethanes and vegetable oil-based polymer nanocomposites have been showing fruitful advantages across a spectrum of potential field of applications.Mesua ferreaL. seed oil-based hyperbranched polyurethane (HBPU)/clay nanocomposites were prepared at different dose levels by in situ polymerization technique. The performances of epoxy-cured thermosetting nanocomposites are reported for the first time. The partially exfoliated structure of clay layers was confirmed by XRD and TEM. FTIR spectra indicate the presence of H bonding between nanoclay and the polymer matrix. The present investigation outlines the significant improvement of tensile strength, scratch hardness, thermostability, water vapor permeability, and adhesive strength without much influencing impact resistance, bending, and elongation at break of the nanocomposites compared to pristine HBPU thermoset. An increment of two times the tensile strength, 6 °C of melting point, and 111 °C of thermo-stability were achieved by the formation of nanocomposites. An excellent shape recovery of about 96–99% was observed for the nanocomposites. Thus, the formation of partially exfoliated clay/vegetable oil-based hyperbranched polyurethane nanocomposites significantly improved the performance. PMID:20596546

  18. Nanoporous clay with carbon sink and pesticide trapping properties

    NASA Astrophysics Data System (ADS)

    Woignier, T.; Duffours, L.; Colombel, P.; Dieudonné, P.

    2015-07-01

    A thorough understanding of the mechanisms and factors involved in the dynamics of organic carbon in soils is required to identify and enhance natural sinks for greenhouse gases. Some tropical soils, such as Andosols, have 3-6 fold higher concentrations of organic carbon than other kinds of soils containing classical clays. In the tropics, toxic pesticides permanently pollute soils and contaminate crops, water resources, and ecosystems. However, not all soils are equal in terms of pesticide contamination or in their ability to transfer pollution to the ecosystem. Andosols are generally more polluted than the other kinds of soils but, surprisingly, they retain and trap more pesticides, thereby reducing the transfer of pesticides to ecosystems, water resources, and crops. Andosols thus have interesting environmental properties in terms of soil carbon sequestration and pesticide retention. Andosols contain a nano porous clay (allophane) with unique structures and physical properties compared to more common clays; these are large pore volume, specific surface area, and a tortuous and fractal porous arrangement. The purpose of this mini review is to discuss the importance of the allophane fractal microstructure for carbon sequestration and pesticide trapping in the soil. We suggest that the tortuous microstructure (which resembles a labyrinths) of allophane aggregates and the associated low accessibility partly explain the poor availability of soil organic matter and of any pesticides trapped in andosols.

  19. Ni(II) removal from aqueous effluents by silylated clays.

    PubMed

    Carvalho, Wagner A; Vignado, Carolina; Fontana, Juliane

    2008-05-30

    Industrial effluents discharged in water bodies without proper treatment contribute to water pollution by potentially toxic metal ions. Considering that the legislation for discarding of such effluents is getting more and more rigorous, the development of efficient processes for the treatment of industrial effluents is of great interest. A study on the capacity of metal retention by silylated-modified clays was carried out with the aim to evaluate the efficiency of this application. K10 clay was modified with 3-mercaptopropyltrimethoxysilane (MPS) and tested in batch removal processes. We investigated the sorption process, obtaining isotherms and kinetics of adsorption and the influence of pH, the desorption process and the metal recovery. It was observed that the modified clay presents fast retention and good capacity of both adsorption and desorption. The use of K10/MPS as adsorbent shows to be more adequate in effluent final polishment, after a conventional treatment, or when Ni(II) initial concentration in the effluent is low enough to permit its adequate removal by conventional methods. PMID:17980481

  20. Chlordecone retention in the fractal structure of volcanic clay.

    PubMed

    Woignier, Thierry; Clostre, Florence; Macarie, Hervé; Jannoyer, Magalie

    2012-11-30

    Chlordecone (CHLD), a soil and foodstuff pollutant, as well as an environmentally persistent organochlorine insecticide, was used intensively in banana fields. The chlordecone uptake of three crops was measured for two types of polluted soils: allophanic and non-allophanic. The uptake is lower for allophanic soils even if their chlordecone content is higher than with non-allophanic soils. The fractal structure of the allophane aggregates was characterized at the nanoscale by small angle X-rays scattering, pore size distribution and transmission electron microscopy. We showed that clay microstructures should be an important physico-chemical factor governing the fate of chlordecone in the environment. Allophanic clays result in two counterintuitive findings: higher contaminant trappings yet lower contaminant availability. We propose that this specific, tortuous structure, along with its associated low accessibility, partly explains the low availability of chlordecone confined in allophanic soils. Capsule The fractal and tortuous microstructure of allophane clay favours the chlordecone retention in soils and disfavours the crop uptake. PMID:23062511

  1. Clay Nanocomposite/Aerogel Sandwich Structures for Cryotanks

    NASA Technical Reports Server (NTRS)

    Miller, Sandi; Leventis, Nicholas; Johnston, J. Chris; Meador, Michael

    2006-01-01

    GRC research has led to the development of epoxy-clay nanocomposites with 60-70% lower gas permeability than the base epoxy resin. Filament wound carbon fiber reinforced tanks made with this nanocomposite had a five-fold lower helium leak rate than the corresponding tanks made without clay. More recent work has produced new composites with more than a 100-fold reduction in helium permeability. Use of these advanced, high barrier composites would eliminate the need for a liner in composite cryotanks, thereby simplifying construction and reducing propellant leakage. Aerogels are attractive materials for use as cryotank insulation because of their low density and low thermal conductivity. However, aerogels are fragile and have poor environmental stability, which have limited their use to certain applications in specialized environments (e.g., in certain types of nuclear reactors as Cerenkov radiation detectors, and as thermal insulators aboard space rovers on Mars). New GRC developed polymer crosslinked aerogels (X-Aerogels) retain the low density of conventional aerogels, but they demonstrate a 300-fold increase in their mechanical strength. Currently, our strongest materials combine a density of approx. 0.45 g/cc, a thermal conductivity of approx. 0.04 W/mK and a compressive strength of 185 MPa. Use of these novel aerogels as insulation materials/structural components in combination with the low permeability of epoxy-clay nanocomposites could significantly reduce cryotank weight and improve durability.

  2. Enrofloxacin uptake and retention on different types of clays

    NASA Astrophysics Data System (ADS)

    Wan, Miao; Li, Zhaohiu; Hong, Hanlie; Wu, Qingfeng

    2013-11-01

    The adsorption and retention of enrofloxacin (EN) on different types of clays was studied in batch tests under different pH, contact time, and initial concentration conditions. XRD and FTIR analyses were utilized to characterize EN adsorption and to elucidate mechanisms of EN adsorption. The EN adsorption equilibrium followed the Langmuir isotherm and reached capacities of 667, 228 and 20 mmol/kg at pH 4-5 on the montmorillonite (SWy-2), illite (IMt-2), and kaolinite (KGa-1b), respectively. The pseudo-second-order model fitted the EN sorption kinetics well. Although EN had a much lower adsorption capacity on KGa-1b compared to that on the other two clays, the adsorption rate constant was the fastest at 0.73 kg/mmol-h. Cation exchange interaction was attributed to the major mechanism for EN adsorption on SWy-2 and IMt-2, and non-electrostatic interactions attributed to EN adsorption when solution pH was above 7. Intercalation of EN molecules into the interlayer space of SWy-2 was confirmed by the XRD patterns after EN adsorption. In contrast, the basal spacing and intensity remained the same after EN adsorption on IMt-2 and KGa-1b, indicating that the EN adsorption on the non-swelling clays were limited to the external surfaces.

  3. Engineered clay-shredded tyre mixtures as barrier materials

    SciTech Connect

    Al-Tabbaa, A.; Aravinthan, T.

    1997-12-31

    An engineered clay consisting of kaolin and bentonite was mixed with shredded tyre in various weight percentages and examined for use as a constituent in a landfill liner. The clay-tyre mixtures properties in terms of compaction, unconfined compressive strength, permeability to water and paraffin, leachability, stress-strain behaviour, free swell behaviour and swelling pressure were investigated. The results show that the dry density and strength reduced with the addition of tyre and also with increased tyre content but that good interaction was developed between the clay and tyre. The strain at failure increased showing reinforcing effect of the tyre. The permeability to paraffin was considerably reduced compared to that to water due to the presence of the tyre which caused high swelling pressures to develop. The leachability results indicate initial high concentrations leaching out of the soil-tyre mixtures which will be subjected to dilution in the environment. This work adds evidence to the potential advantages of using soil-tyre mixtures as a landfill liner material.

  4. Electrokinetic potentials of clay surfaces modified by polymers

    SciTech Connect

    Sondi, I.; Pravdic, V.; Milat, O.

    1997-05-01

    This paper describes the influence of two polymers, fulvic acid (FA) and polyacrylic acids (PAAs) of comparable molecular mass, on the electrokinetic potential of model surfaces encountered in clay minerals: silica (SiO{sub 2}), aluminum oxide ({gamma}-Al{sub 2}O{sub 3}), and gibbsite [{gamma}-Al(OH){sub 3}]. Measurements at pH 6.5 {+-} 0.2 show that FA and PAAs modify the potentials of aluminum oxide and gibbsite, but leave the silica surface unchanged. A chlorite clay mineral (ripidolite), milled to increase the numbers of oxy-hydroxy groups at newly created surfaces, was exposed to FA and PAAs, carriers of carboxylic groups, to study their influence on electrokinetic potential. The key to the interaction is that polymers hold metal ions (Al, Mg, Fe) in the edge surfaces, while siloxane groups show limited interaction or none at all. The results offer an explanation of why clay mineral particles are always negatively charged in natural waters.

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

    NASA Astrophysics Data System (ADS)

    Omurlu, Cigdem; Pham, H.; Nguyen, Q. P.

    2016-05-01

    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.

  6. Adsorption and separation of proteins by a smectitic clay mineral.

    PubMed

    Ralla, Kathrin; Sohling, Ulrich; Riechers, Daniel; Kasper, Cornelia; Ruf, Friedrich; Scheper, Thomas

    2010-09-01

    The adsorption of proteins by a smectitic clay mineral was investigated. The clay used in this study is a mixture of montmorillonite and amorphous SiO(2). Due to the high porosity the montmorillonite units are accessible for protein adsorption. The amorphous silica prevents the montmorillonite from swelling and allows column packing. Protein adsorption was performed at different pH under static conditions. Furthermore, static capacities were determined. The material reveals high adsorption capacities for proteins under static conditions (270-408 mg/g), whereby proteins are mainly adsorbed via electrostatic interactions. The Freundlich isotherm is suggested as an adsorption model. For desorption a pH shift was found to be most effective. Binding and elution of human serum albumin and ovalbumin were tested under dynamic conditions. Dynamic capacities of about 40 mg/g for ovalbumin at 764 cm/h were found. The clay mineral provides suitable properties for the application as cost-efficient, alternative separation material. PMID:20340034

  7. Hydrogel membranes of PVAl/ clay by gamma radiation

    NASA Astrophysics Data System (ADS)

    de Oliveira, M. J. A.; Parra, D. F.; Amato, V. S.; Lugão, A. B.

    2013-03-01

    In the last decades several studies concerning the new methods for drug delivery system have been investigated. A new field known as "smart therapy" involves devices and drug delivery systems to detect, identify and treat the site affected by the disease, not interfering with the biological system. Cutaneous Leishmaniasis is an endemic disease that is characterized by the development of single or multiple localized lesions on exposed areas of skin and one coetaneous treatment could be a potential solution. The aim of this study was to obtain polymeric hydrogel matrices of poly(vinylalcohol)(PVAl) and chitosan with inorganic nanoparticles, which can release a drug according to the need of the treatment of injury caused by leishmania on the skin. The hydrogels matrices were obtained with PVAl/ chitosan and PVAl/ chitosan 0.5; 1.0 and 1.5% laponite RD clay, crosslinked by ionizing gamma radiation with dose of 25 kGy. The techniques used for characterization were swelling, gel fraction, Fourier transform infrared spectroscopy (FTIR) and thermogravimetry (TGA). After synthesis, the samples were immersed in distilled water and weighed in periods of time until 60 h for the swelling determination. The obtained results have indicated that the swelling of the membranes increases with clay concentration, in consequence of ionic groups present in the clay.

  8. Liquid clay emulsion--alternate daily cover and erosion

    SciTech Connect

    Martell, L.

    1995-12-31

    Formula 480 Biodegradable Clay Based Product, developed in 1985, is a non-toxic liquid bentonite clay product that comes in concentrate form for dilution with water and/or leachate. The concentrate allows this product y to be used for erosion and dust control, grass seeding, as well as a daily or intermediate cover for landfills. It inhibits the activities of birds and vectors, while controlling dust, erosion, odor, and blowing debris. By varying the dilution of Formula 480, the product can be set up from porous and flexible, to durable and waterproof. Having a clay base, high cation exchange capacity offers nutrient stabilization for grass seeding. When using leachate for product dilution, it will percolate, waterproof, and be recycled back into the surface as a solid. The product is economical at $.03 to $.08/sq.ft., depending on thickness of application, smoothness of surface or compaction ratio. Application is done with a self-contained sprayer developed specifically for Formula 480. It can be sprayed with a high volume handgun or an economical and efficient spray boom. This product is cleared for use in over 15 states and is currently being used on hazardous and non-hazardous fills throughout the U.S. and Germany. Ease of application, economy, and effectiveness warrants people to look at this product for many uses.

  9. Crystallization and textural porosity of synthetic clay minerals.

    SciTech Connect

    Carrado, K. A.; Csencsits, R.; Thiyagarajan, P.; Seifert, S.; Macha, S. M.; Harwood, J.; Univ. of Illinois at Chicago; IIT

    2002-12-01

    The crystallization of synthetic layered magnesium silicate hectorite clays from both silica sol and organosilane sources is compared. For the silica sol-derived clays, a templating method is employed wherein organic or polymeric molecules are included during clay crystallization that are then removed from the composites via calcination. The mechanism of silane-derived hectorite formation is followed by XRD, TGA, 29Si MAS NMR, and small angle X-ray scattering (SAXS), and results are compared to those obtained for the sol-derived hectorite. The mechanism appears to be similar but the rate is approximately doubled when the silane is used rather than silica sol. Analytical transmission electron microscopy (TEM) is exploited to glean structural morphology information towards resolving the nature of the resulting pore network structures. Results are compared with nitrogen adsorption-desorption isotherm behavior; dominant hysteresis loops are present in the type IV isotherms. Pore size distributions based on both the adsorption and desorption isotherms are compared. Small angle neutron scattering (SANS) experiments reveal that the average particle size increases as synthetic laponite < sol-derived hectorite < silane-derived hectorite < natural hectorite. Contrast matching SANS studies in aqueous and organic solvents are carried out to extract information about pore accessibility.

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

    PubMed

    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. PMID:25135171

  11. In situ determination of anisotropic permeability of clay

    NASA Astrophysics Data System (ADS)

    Shao, H.; Sönnke, J.; Morel, J.; Krug, S.

    Argillaceous formations are being considered as potential host rocks for repositories of radioactive waste in many countries. For this purpose, the thermal, hydraulic, mechanical, and chemical properties of the clay stone are being widely investigated in the laboratories and in situ. However, clay stone behaves, due to its tectonic evolution of the formation, hydraulically and mechanically transversal isotropic. Argillite bedding or layering structure has been observed in the underground laboratories Mont Terri in the Switzerland and Meuse/Haute-Marne at Bure site in France. Conventional packer systems used for the borehole hydraulic characterisation cannot distinguish the difference between the properties parallel and perpendicular to the bedding. For this purpose, a new ‘slot packer’ system has been developed by the BGR. This type of new packer system is intensively tested in the BGR laboratory and the Mont Terri Rock Laboratory to judge the feasibility. The anisotropic ratio of the Opalinus clay defined by permeability value parallel to the bedding/permeability value perpendicular to the bedding is evaluated up to eight times to one order of magnitude within the HG-B experiment in the Mont Terri Rock Laboratory. Within the cooperation between BGR and ANDRA, the ‘slot packer’ will be used for the measurement of anisotropic permeability of the Callovo-Oxfordien formation at the Bure site.

  12. Disassembly of the cystovirus ϕ6 envelope by montmorillonite clay

    PubMed Central

    Block, Karin A; Trusiak, Adrianna; Katz, Al; Gottlieb, Paul; Alimova, Alexandra; Wei, Hui; Morales, Jorge; Rice, William J; Steiner, Jeffrey C

    2014-01-01

    Prior studies of clay–virus interactions have focused on the stability and infectivity of nonenveloped viruses, yielding contradictory results. We hypothesize that the surface charge distribution of the clay and virus envelope dictates how the components react and affect aggregation, viral stability, and infectivity. The bacteriophage Cystoviridae species φ6 used in this study is a good model for enveloped pathogens. The interaction between φ6 and montmorillonite (MMT) clay (the primary component of bentonite) is explored by transmission electron microscopy. The analyses show that MMT–φ6 mixtures undergo heteroaggregation, forming structures in which virtually all the virions are either sequestered between MMT platelet layers or attached to platelet edges. The virions swell and undergo disassembly resulting in partial or total envelope loss. Edge-attached viral envelopes distort to increase contact area with the positively charged platelet edges indicating that the virion surface is negatively charged. The nucleocapsid (NCs) remaining after envelope removal also exhibit distortion, in contrast to detergent-produced NCs which exhibit no distortion. This visually discernible disassembly is a mechanism for loss of infectivity previously unreported by studies of nonenveloped viruses. The MMT-mediated sequestration and disassembly result in reduced infectivity, suggesting that clays may reduce infectivity of enveloped pathogenic viruses in soils and sediments. PMID:24357622

  13. DE-FG02-06ER15364: Final Technical Report Nanoscale Reactivity of Clays, Clay Analogues (Micas), and Clay Minerals

    SciTech Connect

    Nagy, Kathryn L.

    2008-07-03

    The project objectives were to determine the nanoscale to molecular scale structure of the interface between muscovite mica and aqueous solutions containing various sorbates and to explore systematics that control the incorporation of inorganic and organic chemical components during aging of nanoparticles of iron-oxides and aluminosilicate clays. The basal surface of phyllosilicates is a primary sorbent of environmental contaminants, natural organic matter, and nutrients. Micas are also superb atomically-flat substrates used in materials science and surface physics applications. We applied X-ray scattering techniques using high brilliance synchrotron radiation to investigate molecular-scale details of mica’s interface structure in solutions containing common and toxic cations, anions, and natural organic molecules. Nanoparticles are ubiquitous in the environment and have a high capacity for sorbing contaminants through the combined effects of their high surface areas and pH-dependent surface charge. Aging of nanoparticles from metastable to stable phases can be inhibited by sorption of nonstructural components, but exact mechanisms are unknown. We synthesized Fe-oxides and aluminosilicate clay minerals from aqueous solutions in the presence of selected anions, and organic molecules, and quantified the uptake of these additives during aging and some implications for nanoparticle formation.

  14. Selective Clay Placement within a Silicate Clay-Epoxy Blend Nanocomposite and the Effect on Physical Properties

    NASA Technical Reports Server (NTRS)

    Miller, Sandi G.; Scheiman, Daniel A; Kohlmman, Lee W.

    2009-01-01

    Many epoxy systems under consideration for composite pressure vessels are composed of toughened epoxy resins. In this work, epoxy blends containing both rigid aromatic and flexible aliphatic components were prepared, to model toughened systems, and determine the optimum route of silicate addition. Compositions were chosen such that both glassy and rubbery resins were obtained at room temperature. The physical properties of the nanocomposites varied with T(g) and silicate placement, however, nanocomposite T(g)s were observed which exceeded that of the base resin by greater than 10 C. The tensile strength of the glassy resin remained constant or decreased on the dispersion of clay while that of the rubbery material doubled. Selectively placing the clay in the aliphatic component of the rubbery blend resulted in a greater than 100% increase in material toughness.

  15. Microtectonic analysis of an incipient thrust fault in Opalinus Clay.

    NASA Astrophysics Data System (ADS)

    Laurich, B.; Urai, J. L.; Desbois, G.; Vollmer, C.; Nussbaum, C.

    2014-12-01

    The microfabric of a fault rock controls the fault's mechanical and hydrological properties. Knowing the fabric is thus essential for estimating seismic behavior and potential fluid flow. We studied well-preserved core and outcrop samples from the Main Fault, an up to 3 m wide zone of approximately 10 m offset in the Mont Terri Underground Research Laboratory (CH), a site to evaluate long-term safety of radioactive waste disposal. We found four main structural elements: (1) slickensided shear surfaces, (2) veins, (3) fine-grained gouge, and (4) scaly clay fabric. We investigated each element by ultra-thin section microscopy, by broad-ion-beam scanning electron microscopy (BIB-SEM) and focused-ion-beam transmission electron microscopy (FIB-TEM), by X-ray diffraction crystallography (XRD) and by naked-eye analysis. We found extremely thin shear zones (<4μm) along which several samples broke, revealing slickensides. BIB-SEM and FIB-TEM showed that these thin shear zones comprise strongly aligned nano-sized clay particles. The porosity of the shear zones is dramatically reduced compared to the protolith. The strong alignment of clay particles, which wrap larger grains as quartz, calcite fossils and feldspar, yields a shiny, smooth surface morphology of the slickensides. Occasionally, calcite and celestite veins are associated to releasing sections such as risers of the slickenside. Gouge comprises much finer particles, a higher fabric intensity and a strong reduction in porosity and calcite content compared to the protolith. These findings suggest that gouge evolved by a cataclastic deformation mechanism aided by pressure solution of calcite. Scaly clay occurs in varying intensity and comprises thin shear zones, which sometimes act as flexural-slip faults of microfolds and C'-type shear bands. We propose that next to cataclastic processes, pressure solution and precipitation are important micro-scale mechanisms in faulting in Opalinus Clay and thus need to be

  16. Sorption of high explosives to water-dispersible clay: influence of organic carbon, aluminosilicate clay, and extractable iron.

    PubMed

    Dontsova, Katerina M; Hayes, Charolett; Pennington, Judith C; Porter, Beth

    2009-01-01

    Explosives in soils can present environmental problems for military installations. Fine, mobile particles represent the most reactive fraction of the soil and, therefore, are expected to adsorb explosives and potentially facilitate their transport. The objective of this study was to determine the relative significance of phyllosilicate clay, organic matter, and two forms of extractable iron in adsorption of 2,4,6-trinitrotoluene (TNT) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) by the colloidal water-dispersible clay (WDC) fraction of the soil. The WDC fraction of two mineral and one organic soil was separated and then treated to remove organic carbon (OC) and several forms of iron (Fe(o), oxalate extractable, and Fe(d), dithionite-citrate extractable). Adsorption coefficients were determined for whole soils, untreated, and treated WDC. For mineral soils, adsorption of TNT and RDX on the WDC was greater than on the whole soil. The presence of OC increased explosives sorption by WDC. When OC was removed, iron interfered with TNT sorption. In the presence of OC, removal of Fe(o) decreased RDX adsorption and increased TNT adsorption indicating different adsorption mechanisms. Organic carbon was a more significant indicator of explosives adsorption by WDC than clays or iron oxides and hydroxides. Therefore, OC is the most likely medium for facilitated transport of TNT and RDX. PMID:19465721

  17. Embedding of laboratory wastes in clay or concrete blocks, with special reference to baking osmic acid and cacodylic acid wastes with clay.

    PubMed

    Murakami, T; Murakami, T; Yamana, S

    1998-12-01

    Liquid laboratory waste containing osmic acid and cacodylic acid was mixed with potter's clay or hydraulic cement. The clay-waste product was kneaded into blocks and baked in a klin (1,200-1,400 degrees C). The cement-waste product was allowed to harden into concrete blocks. Some of the baked clay blocks and concrete blocks were ground, and immersed in 1 N NaOH or 10% HCI solutions for 3-6 months. X-ray microanalysis of the dried samples of these solutions showed that no leakage of osmium and arsenic occurred in the baked clay embedding, and that some leakage of these agents occurred in the concrete embedding. The present study indicates that the baked clay embedding method is useful for safe storage of dangerous laboratory wastes. Additional experiments suggested that glass embedding is also useful for safe storage of laboratory wastes or harmful metals. PMID:9876766

  18. Treatment with coated layer double hydroxide clays decreases the toxicity of copper-contaminated water.

    PubMed

    Blake, Deanne; Nar, Mangesh; D'Souza, Nandika Anne; Glenn, J Brad; Klaine, Stephen J; Roberts, Aaron P

    2014-05-01

    Copper is a common pollutant found in watersheds that exerts toxic effects on both invertebrates and vertebrates. Layer double hydroxide (LDH) clays are able to adsorb a wide range of contaminants through ion-exchange mechanisms. Coating LDH clays with various materials alters the aggregation of clay particles into the nano-size range, thus increasing relative surface area and offering great potential for contaminant remediation. The goal of this study was to determine if treatment with coated LDH clays decreases the toxicity of copper-containing solutions to Daphnia magna. Four LDH clays with different coatings used to alter hydrophobicity were as follows: used: Na(+) montmorillonite, Zn-Al LDH-nitrate, Zn-Al LDH-stearate, and Zn-Al LDH-carbonate. It was determined that coated LDH clays decreased copper toxicity by decreasing bioavailability and that smaller aggregate sizes decreased bioavailability the most. 96 h LC50 values increased by as much as 4.2 times with the treatment of the solutions with 100 mg/L LDH clay. Copper analysis of the clay and solutions indicated that the clays work by decreasing copper bioavailability by way of a binding mechanism. Coated LDH clays hold promise as a small-scale remediation tool or as an innovative tool for toxicity identification and evaluation characterization of metals. PMID:24442186

  19. Effect of red clay on diesel bioremediation and soil bacterial community.

    PubMed

    Jung, Jaejoon; Choi, Sungjong; Hong, Hyerim; Sung, Jung-Suk; Park, Woojun

    2014-08-01

    Red clay is a type of soil, the red color of which results from the presence of iron oxide. It is considered an eco-friendly material, with many industrial, cosmetic, and architectural uses. A patented method was applied to red clay in order to change its chemical composition and mineral bioavailability. The resulting product was designated processed red clay. This study evaluates the novel use of red clay and processed red clay as biostimulation agents in diesel-contaminated soils. Diesel biodegradation was enhanced in the presence of red clay and processed red clay by 4.9- and 6.7-fold, respectively, and the number of culturable bacterial cells was correlated with the amount of diesel biodegradation. The growth of Acinetobacter oleivorans DR1, Pseudomonas putida KT2440, and Cupriavidus necator was promoted by both types of red clays. Culture-independent community analysis determined via barcoded pyrosequencing indicated that Nocardioidaceae, Xanthomonadaceae, Pseudomonadaceae, and Caulobacteraceae were enriched by diesel contamination. Bacterial strain isolation from naphthalene- and liquid paraffin-amended media was affiliated with enriched taxa based on 16S rRNA gene sequence identity. We suggest that the biostimulating mechanism of red clay and processed red clay is able to support bacterial growth without apparent selection for specific bacterial species. PMID:24743885

  20. Towards an understanding of the role of clay minerals in crude oil formation, migration and accumulation

    NASA Astrophysics Data System (ADS)

    Wu, Lin Mei; Zhou, Chun Hui; Keeling, John; Tong, Dong Shen; Yu, Wei Hua

    2012-12-01

    This article reviews progress in the understanding of the role of clay minerals in crude oil formation, migration and accumulation. Clay minerals are involved in the formation of kerogen, catalytic cracking of kerogen into petroleum hydrocarbon, the migration of crude oil, and the continued change to hydrocarbon composition in underground petroleum reservoirs. In kerogen formation, clay minerals act as catalysts and sorbents to immobilize organic matter through ligand exchange, hydrophobic interactions and cation bridges by the mechanisms of Maillard reactions, polyphenol theory, selective preservation and sorptive protection. Clay minerals also serve as catalysts in acid-catalyzed cracking of kerogen into petroleum hydrocarbon through Lewis and Brønsted acid sites on the clay surface. The amount and type of clay mineral affect the composition of the petroleum. Brønsted acidity of clay minerals is affected by the presence and state of interlayer water, and displacement of this water is a probable driver in crude oil migration from source rocks. During crude oil migration and accumulation in reservoirs, the composition of petroleum is continually modified by interaction with clay minerals. The clays continue to function as sorbents and catalysts even while they are being transformed by diagenetic processes. The detail of chemical interactions and reaction mechanisms between clay minerals and crude oil formation remains to be fully explained but promises to provide insights with broader application, including catalytic conversion of biomass as a source of sustainable energy into the future.

  1. Molecular Mechanisms of Enhanced Bacterial Growth on Hexadecane with Red Clay.

    PubMed

    Jung, Jaejoon; Jang, In-Ae; Ahn, Sungeun; Shin, Bora; Kim, Jisun; Park, Chulwoo; Jee, Seung Cheol; Sung, Jung-Suk; Park, Woojun

    2015-11-01

    Red clay was previously used to enhance bioremediation of diesel-contaminated soil. It was speculated that the enhanced degradation of diesel was due to increased bacterial growth. In this study, we selected Acinetobacter oleivorans DR1, a soil-borne degrader of diesel and alkanes, as a model bacterium and performed transcriptional analysis using RNA sequencing to investigate the cellular response during hexadecane utilization and the mechanism by which red clay promotes hexadecane degradation. We confirmed that red clay promotes the growth of A. oleivorans DR1 on hexadecane, a major component of diesel, as a sole carbon source. Addition of red clay to hexadecane-utilizing DR1 cells highly upregulated β-oxidation, while genes related to alkane oxidation were highly expressed with and without red clay. Red clay also upregulated genes related to oxidative stress defense, such as superoxide dismutase, catalase, and glutaredoxin genes, suggesting that red clay supports the response of DR1 cells to oxidative stress generated during hexadecane utilization. Increased membrane fluidity in the presence of red clay was confirmed by fatty acid methyl ester analysis at different growth phases, suggesting that enhanced growth on hexadecane could be due to increased uptake of hexadecane coupled with upregulation of downstream metabolism and oxidative stress defense. The monitoring of the bacterial community in soil with red clay for a year revealed that red clay stabilized the community structure. PMID:25956940

  2. Pore space analysis of NAPL distribution in sand-clay media

    USGS Publications Warehouse

    Matmon, D.; Hayden, N.J.

    2003-01-01

    This paper introduces a conceptual model of clays and non-aqueous phase liquids (NAPLs) at the pore scale that has been developed from a mathematical unit cell model, and direct micromodel observation and measurement of clay-containing porous media. The mathematical model uses a unit cell concept with uniform spherical grains for simulating the sand in the sand-clay matrix (???10% clay). Micromodels made with glass slides and including different clay-containing porous media were used to investigate the two clays (kaolinite and montmorillonite) and NAPL distribution within the pore space. The results were used to understand the distribution of NAPL advancing into initially saturated sand and sand-clay media, and provided a detailed analysis of the pore-scale geometry, pore size distribution, NAPL entry pressures, and the effect of clay on this geometry. Interesting NAPL saturation profiles were observed as a result of the complexity of the pore space geometry with the different packing angles and the presence of clays. The unit cell approach has applications for enhancing the mechanistic understanding and conceptualization, both visually and mathematically, of pore-scale processes such as NAPL and clay distribution. ?? 2003 Elsevier Science Ltd. All rights reserved.

  3. Metal adsorption and desorption characteristics of surfactant-modified clay complexes

    SciTech Connect

    Malakul, P.; Srinivasan, K.R.; Wang, H.Y.

    1998-11-01

    Several modified clays have been designed and created for selective removal and recovery of heavy metals such as Cd, Cu, Cr, etc. These surfactant-clay complexes were prepared using hectorite or montmorillonite as the base clay. A simple two-step approach has been developed to synthesize these modified-clay complexes through ion exchange and hydrophobic anchoring of several surfactants such as long-chain alkyldiamines, long-chain dialkylamines, and long-chain carboxylic acids onto the clay matrices. The adsorption capacities and affinity constants of the modified clays can be found to approach those of commercial chelating resin (Chelex 100, Bio-Rad). Using cadmium as a model metal and montmorillonite-cetylbenzyldimethylammonium-palmitic acid (M-CBDA-PA) as a model modified-clay complex, the maximum adsorption capacity of the modified clay is found to be 42 {+-} 0.8 mg/g of clay and the affinity constant is 3.0 {+-} 0.1 mg/L. The metal adsorption has been shown to be mainly through chemical complexation rather than ion exchange. The immobilization of the metal ions is pH dependent, and thus, pH can act as a molecular switch to regenerate the modified-clay complexes.

  4. Investigation of Four Different Laponite Clays as Stabilizers in Pickering Emulsion Polymerization.

    PubMed

    Brunier, Barthélémy; Sheibat-Othman, Nida; Chniguir, Mehdi; Chevalier, Yves; Bourgeat-Lami, Elodie

    2016-06-21

    Clay-armored polymer particles were prepared by emulsion polymerization in the presence of Laponite platelets that adsorb at the surface of latex particles and act as stabilizers during the course of the polymerization. While Laponite RDS clay platelets are most often used, the choice of the type of clay still remains an open issue that is addressed in the present article. Four different grades of Laponite were investigated as stabilizers in the emulsion polymerization of styrene. First, the adsorption isotherms of the clays, on preformed polystyrene particles, were determined by ICP-AES analysis of the residual clay in the aqueous phase. Adsorption of clay depended on the type of clay at low concentrations corresponding to adsorption as a monolayer. Adsorption of clay particles as multilayers was observed for all the grades above a certain concentration under the considered ionic strength (mainly due to the initiator ionic species). The stabilization efficiency of these clays was investigated during the polymerization reaction (free of any other stabilizer). The clays did not have the same effect on stabilization, which was related to differences in their compositions and in their adsorption isotherms. The different grades led to different polymer particles sizes and therefore to different polymerization reaction rates. Laponite RDS and S482 gave similar results, ensuring the best stabilization efficiency and the fastest reaction rate; the number of particles increased as the clay concentration increased. Stabilization with Laponite XLS gave the same particles size and number as the latter two clays at low clay concentrations, but it reached an upper limit in the number of nucleated polymer particles at higher concentrations indicating a decrease of stabilization efficiency at high concentrations. Laponite JS did not ensure a sufficient stability of the polymer particles, as the polymerization results were comparable to a stabilizer-free polymerization system

  5. Clays Can Decrease Gaseous Nutrient Losses from Soil-Applied Livestock Manures.

    PubMed

    Pratt, Chris; Redding, Matthew; Hill, Jaye; Brown, Grant; Westermann, Maren

    2016-03-01

    Clays could underpin a viable agricultural greenhouse gas (GHG) abatement technology given their affinity for nitrogen and carbon compounds. We provide the first investigation into the efficacy of clays to decrease agricultural nitrogen GHG emissions (i.e., NO and NH). Via laboratory experiments using an automated closed-vessel analysis system, we tested the capacity of two clays (vermiculite and bentonite) to decrease NO and NH emissions and organic carbon losses from livestock manures (beef, pig, poultry, and egg layer) incorporated into an agricultural soil. Clay addition levels varied, with a maximum of 1:1 to manure (dry weight). Cumulative gas emissions were modeled using the biological logistic function, with 15 of 16 treatments successfully fitted ( < 0.05) by this model. When assessing all of the manures together, NH emissions were lower (×2) at the highest clay addition level compared with no clay addition, but this difference was not significant ( = 0.17). Nitrous oxide emissions were significantly lower (×3; < 0.05) at the highest clay addition level compared with no clay addition. When assessing manures individually, we observed generally decreasing trends in NH and NO emissions with increasing clay addition, albeit with widely varying statistical significance between manure types. Most of the treatments also showed strong evidence of increased C retention with increasing clay additions, with up to 10 times more carbon retained in treatments containing clay compared with treatments containing no clay. This preliminary assessment of the efficacy of clays to mitigate agricultural GHG emissions indicates strong promise. PMID:27065411

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

    USGS Publications Warehouse

    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.

  7. Gas breakthrough and emission through unsaturated compacted clay in landfill final cover

    SciTech Connect

    Ng, C.W.W.; Chen, Z.K.; Coo, J.L.; Chen, R.; Zhou, C.

    2015-10-15

    Highlights: • Explore feasibility of unsaturated clay as a gas barrier in landfill cover. • Gas breakthrough pressure increases with clay thickness and degree of saturation. • Gas emission rate decreases with clay thickness and degree of saturation. • A 0.6 m-thick clay layer may be sufficient to meet gas emission rate limit. - Abstract: Determination of gas transport parameters in compacted clay plays a vital role for evaluating the effectiveness of soil barriers. The gas breakthrough pressure has been widely studied for saturated swelling clay buffer commonly used in high-level radioactive waste disposal facility where the generated gas pressure is very high (in the order of MPa). However, compacted clay in landfill cover is usually unsaturated and the generated landfill gas pressure is normally low (typically less than 10 kPa). Furthermore, effects of clay thickness and degree of saturation on gas breakthrough and emission rate in the context of unsaturated landfill cover has not been quantitatively investigated in previous studies. The feasibility of using unsaturated compacted clay as gas barrier in landfill covers is thus worthwhile to be explored over a wide range of landfill gas pressures under various degrees of saturation and clay thicknesses. In this study, to evaluate the effectiveness of unsaturated compacted clay to minimize gas emission, one-dimensional soil column tests were carried out on unsaturated compacted clay to determine gas breakthrough pressures at ultimate limit state (high pressure range) and gas emission rates at serviceability limit state (low pressure range). Various degrees of saturation and thicknesses of unsaturated clay sample were considered. Moreover, numerical simulations were carried out using a coupled gas–water flow finite element program (CODE-BRIGHT) to better understand the experimental results by extending the clay thickness and varying the degree of saturation to a broader range that is typical at different

  8. Insightful understanding of the role of clay topology on the stability of biomimetic hybrid chitosan-clay thin films and CO2-dried porous aerogel microspheres.

    PubMed

    Frindy, Sana; Primo, Ana; Qaiss, Abou El Kacem; Bouhfid, Rachid; Lahcini, Mohamed; Garcia, Hermenegildo; Bousmina, Mosto; El Kadib, Abdelkrim

    2016-08-01

    Three natural clay-based microstructures, namely layered montmorillonite (MMT), nanotubular halloysite (HNT) and micro-fibrillar sepiolite (SP) were used for the synthesis of hybrid chitosan-clay thin films and porous aerogel microspheres. At a first glance, a decrease in the viscosity of the three gel-forming solutions was noticed as a result of breaking the mutual polymeric chains interaction by the clay microstructure. Upon casting, chitosan-clay films displayed enhanced hydrophilicity in the order CSclay microstructure, an improvement in the mechanical properties of the chitosan-clay films has been substantiated with CS-SP reaching the highest value at 5% clay loading. While clay addition provides a way to resist the shrinkage occurring for native chitosan, the enhanced hydrophilicity associated to the water content affects the efficacy of the CO2 super-critical drying as the most hydrophilic CS-SP microspheres face the highest shrinkage, resulting in a lowest specific surface area compared to CS-HNT and CS-MMT. Chitosan-clay exhibits enhanced thermal properties with the degradation delayed in the order CSclay compared to native chitosan, evidencing the beneficial protective effect of the clay particulates for the biopolymer. However, under hydrothermal treatment, the presence of clay was found to be detrimental to the material stability as a significant shrinkage occurs in hybrid CS-clay microspheres, which is attributed again to their increased hydrophilicity compared to the native polymeric microspheres. In this framework, a peculiar behavior was observed for CS-MMT, with the microspheres standing both against contraction during CO2 gel drying and under hydrothermal conditions. The knowledge gained from this rational design will constitute a guideline toward the preparation of ultra-stable, practically-optimized food

  9. Evaluation of Used Fuel Disposition in Clay-Bearing Rock

    SciTech Connect

    Jové Colón, Carlos F.; Weck, Philippe F.; Sassani, David H.; Zheng, Liange; Rutqvist, Jonny; Steefel, Carl I.; Kim, Kunhwi; Nakagawa, Seiji; Houseworth, James; Birkholzer, Jens; Caporuscio, Florie A.; Cheshire, Michael; Rearick, Michael S.; McCarney, Mary K.; Zavarin, Mavrik; Benedicto, Ana; Kersting, Annie B.; Sutton, Mark; Jerden, James; Frey, Kurt E.; Copple, Jacqueline M.; Ebert, William

    2014-08-01

    Radioactive waste disposal in shale/argillite rock formations has been widely considered given its desirable isolation properties (low permeability), geochemically reduced conditions, anomalous groundwater pressures, and widespread geologic occurrence. Clay/shale rock formations are characterized by their high content of clay minerals such as smectites and illites where diffusive transport and chemisorption phenomena predominate. These, in addition to low permeability, are key attributes of shale to impede radionuclide mobility. Shale host-media has been comprehensively studied in international nuclear waste repository programs as part of underground research laboratories (URLs) programs in Switzerland, France, Belgium, and Japan. These investigations, in some cases a decade or more long, have produced a large but fundamental body of information spanning from site characterization data (geological, hydrogeological, geochemical, geomechanical) to controlled experiments on the engineered barrier system (EBS) (barrier clay and seals materials). Evaluation of nuclear waste disposal in shale formations in the USA was conducted in the late 70’s and mid 80’s. Most of these studies evaluated the potential for shale to host a nuclear waste repository but not at the programmatic level of URLs in international repository programs. This report covers various R&D work and capabilities relevant to disposal of heat-generating nuclear waste in shale/argillite media. Integration and cross-fertilization of these capabilities will be utilized in the development and implementation of the shale/argillite reference case planned for FY15. Disposal R&D activities under the UFDC in the past few years have produced state-of-the-art modeling capabilities for coupled Thermal-Hydrological-Mechanical-Chemical (THMC), used fuel degradation (source term), and thermodynamic modeling and database development to evaluate generic disposal concepts. The THMC models have been developed for shale

  10. Elastic Properties of Clay Minerals Determined by Atomic Force Acoustic Microscopy Technique

    NASA Astrophysics Data System (ADS)

    Kopycinska-Müller, M.; Prasad, M.; Rabe, U.; Arnold, W.

    Seismic wave propagation in geological formations is altered by the presence of clay minerals. Knowledge about the elastic properties of clay is therefore essential for the interpretation and modeling of the seismic response of clay-bearing formations. However, due to the layered structure of clay, it is very difficult to investigate its elastic properties. We measured elastic properties of clay using atomic force acoustic microscopy (AFAM). The forces applied during the experiments were not higher than 50 nN. The adhesion forces were measured from the pull-off forces and included into our calculations by means of the Derjaguin-Mueller-Toporov model for contact mechanics. The obtained values of the elastic modulus for clay varied from 10 to 17 GPa depending on various parameters that describe the dynamics of a vibrating beam

  11. A research on the radiation shielding effects of clay, silica fume and cement samples

    NASA Astrophysics Data System (ADS)

    Akbulut, Suat; Sehhatigdiri, Arvin; Eroglu, Hayrettin; Çelik, Semet

    2015-12-01

    Nowadays, as the application areas of nuclear technology increases, protection from radiation has become even more important. Especially, the importance of radiation-shielding is important for the environment and employees which are in close proximity. Clays can be used as additives for shielding the radioactive materials. In this study, the shielding properties of micronize clay-white cement, clay-silica fume, gypsum, gypsum-silica fume, cement, white cement, cement-silica fume, white cement-gypsum, white cement-silica fume, red mud-silica fume, silica fume and red mud at different energy levels were examined. Additionally, compaction and unconfined compression tests were carried out on the samples. The results of clays and other samples were compared with each other. As a result, it was found that clays, especially clay-white cement mixture were superior than other samples in radioactive shielding.

  12. Magnetorheological behavior of magnetite covered clay particles in aqueous suspensions

    NASA Astrophysics Data System (ADS)

    Galindo-Gonzalez, C.; Lopez-Lopez, M. T.; Duran, J. D. G.

    2012-08-01

    Montmorillonite clay particles coated with magnetite nanoparticles suspended in aqueous media behave as magnetorheological fluids with enhanced stability as compared to conventional ones. In this work, the study of the magnetorheological behavior of these suspensions of magnetite-clay composite particles has been carried out. For this purpose, both steady and dynamic rheological measurements were carried out in the absence and in the presence of external magnetic fields. In the first kind of experiments, the rheograms of the suspensions (shear stress versus shear rate plot) are analyzed as a function of the strength of the magnetic field applied. In the second one, oscillatory stresses are applied to the system, and the storage modulus is studied as a function of the external magnetic field. In the absence of magnetic field, the suspensions develop a weak yield stress due to the aggregation of the magnetite covered clay particles. In the presence of magnetic field, the yield stress is strongly dependent on the magnetic field strength inside the samples, demonstrating that the suspensions experience a magnetorheological effect, moderate when the magnetic field strength is weak and stronger for values of magnetic field higher than 150-200 kA/m. Actually, the most intriguing result is the change of the trend in the dependence of the yield stress with the field. This dependence is approximately linear with the field for strength values smaller than 150-200 kA/m. On the other hand, for higher values, the yield stress increases with magnetic field following a power law with exponent 4.5.The results are interpreted by means of a model that relates the structure of the particles in the suspensions to the magnetic field applied and using the interaction energy between particles calculated by the extended DLVO theory to include magnetic interaction.

  13. Synthetic clay-magnetite aggregates designed for controlled deposition experiments

    NASA Astrophysics Data System (ADS)

    Feinberg, J. M.; Galindo-Gonzalez, C.; Kasama, T.; Cervera, L.; Posfai, M.; Harrison, R. J.; Dunin-Borkowski, R. E.

    2007-12-01

    The behavior of magnetic particles in fluid environments is key to the acquisition of detrital remanence magnetization and is essential to a multitude of industrial applications. This study introduces a series of synthetic clay-magnetite aggregates whose physical attributes can be tailored for controlled depositional experiments. We describe the mineralogical structure and magnetic behavior of montmorillonite platelets coated with nanometer-scale magnetite crystals using both electron microscopy and rock magnetism techniques. Selected area electron diffraction of the magnetite and the montmorillonite host shows no evidence of preferred orientation or oriented aggregation. Grain size distributions of magnetite in three different clay-magnetite assemblages were directly measured using conventional bright-field transmission electron microscopy. The spacing of the magnetite grains and their three-dimensional distribution around individual clay platelets was imaged using a tomographic reconstruction generated from high-angle annular dark-field (HAADF) images. The grain size distributions determined from the bright-field images and the tomographic reconstruction agree within error with estimates derived from magnetic granulometry techniques based on magnetic hysteresis and low-field susceptibility measurements. All three samples behave superparamagnetically at room temperature, and display increasing levels of single domain behavior as the samples are cooled to liquid nitrogen temperatures (- 195°C). Off-axis electron holography images show that superparamagnetic grains are also stabilized into flux closure structures at -195°C. The average spacing between adjacent magnetite crystals and the overall platelet shape of the aggregates creates an anisotropy of magnetic susceptibility that allows assemblages to align with external magnetic fields at room temperature. By adjusting the dimensions and concentrations of the magnetite grains in these aggregates, we can create

  14. Fate and Tranport of MTBE in Clay-Rich Materials

    NASA Astrophysics Data System (ADS)

    lenczewski, m e

    2001-12-01

    A recent report by the U.S. Geological Survey identified methyl tert-butyl ether (MTBE), a constituent of reformulated gasoline, as the most common contaminant of urban aquifers in the United States. MTBE has been released into groundwater supplies by leaking underground fuel tanks. In Illinois, it has been found in 26 of the 1,800 public water supplies and although detection was intermittent, levels were high enough to be offensive to users in some Illinois communities. MTBE is also being used in Mexico to solve the problem of air quality; however, it has the potential to harm the drinking water quality in the process. Early research on MTBE considered it resistant to biodegradation and unable to adsorb to soils and sediments. However, recent evidence indicates that biodegradation does occur under certain conditions and that sorption can occur to organic materials. This research project will investigate the biodegradation of MTBE and its sorption to the clay-rich glacial till found in northern Illinois and lacustrine clays found in the Chalco Basin, Mexico City, Mexico whose interaction with MTBE has not previously been studied. The principal hypothesis of this research is that the microorganisms and environmental factors in clay-rich materials will increase the biodegradation and sorption of MTBE as compared to sandy materials. The experiments will simulate a spill of MTBE or downgradient from a gasoline spill. Microcosms and batch isotherm experiments will be used to demonstrate the potential for biodegradation and sorption in these materials; however, laboratory results are not considered reliable estimates of actual field sorption and biodegradation rates. Therefore long-term column experiments will also be conducted in which large sample volumes of material that simulate the heterogeneities naturally observed in the environment. This research will increase understanding of the biodegradation and sorption of MTBE and lay the necessary groundwork to implement

  15. STS-118 Astronauts Rick Mastracchio and Clay Anderson Perform EVA

    NASA Technical Reports Server (NTRS)

    2007-01-01

    As the construction continued on the International Space Station (ISS), STS-118 astronaut and mission specialist Rick Mastracchio was anchored on the foot restraint of the Canadarm2 as he participated in the third session of Extra Vehicular Activity (EVA) for the mission. Assisting Mastracchio was Expedition 15 flight engineer Clay Anderson (out of frame). During the 5 hour, 28 minute space walk, the two relocated the S-band Antenna Sub-Assembly from the Port 6 (P6) truss to the Port 1 (P1) truss, installed a new transponder on P1 and retrieved the P6 transponder.

  16. Effect of wet grinding on structural properties of ball clay

    SciTech Connect

    Purohit, A. Chander, S.; Dhaka, M. S.; Hameed, A.; Singh, P.; Nehra, S. P.

    2015-05-15

    In this paper, the effect of wet grinding on structural properties of ball clay is undertaken. The wet grinding treatment was performed employing ball and vibro mills for different time spells of 2, 4, 8 and 16 hours. The structural properties were carried out using X-ray diffraction (XRD). The structure of ground samples is found to be simple cubic. The crystallographic parameters are calculated and slight change in lattice constant, inter planner spacing and particle size is observed with grinding treatment. The results are in agreement with the available literature.

  17. Survival of microorganisms in smectite clays - Implications for Martian exobiology

    NASA Technical Reports Server (NTRS)

    Moll, Deborah M.; Vestal, J. R.

    1992-01-01

    The survival of Baccillus subtilis, Azotobacter chroococcum, and the enteric bacteriophage MS2 has been examined in clays representing terrestrial (Wyoming type montmorillonite) and Martian (Fe3+ montmorillonite) soils exposed to terrestrial and Martian environmental conditions of temperature and atmospheric composition and pressure. An important finding is that MS2 survived simulated Mars conditions better than the terrestrial environment, probably owing to stabilization of the virus caused by the cold and dry conditions of the simulated Mars environment. This finding, the first published indication that viruses may be able to survive in Mars-type soils, may have important implications for future missions to Mars.

  18. Clay nanotube-biopolymer composite scaffolds for tissue engineering

    NASA Astrophysics Data System (ADS)

    Naumenko, Ekaterina A.; Guryanov, Ivan D.; Yendluri, Raghuvara; Lvov, Yuri M.; Fakhrullin, Rawil F.

    2016-03-01

    Porous biopolymer hydrogels doped at 3-6 wt% with 50 nm diameter/0.8 μm long natural clay nanotubes were produced without any cross-linkers using the freeze-drying method. The enhancement of mechanical strength (doubled pick load), higher water uptake and thermal properties in chitosan-gelatine-agarose hydrogels doped with halloysite was demonstrated. SEM and AFM imaging has shown the even distribution of nanotubes within the scaffolds. We used enhanced dark-field microscopy to visualise the distribution of halloysite nanotubes in the implantation area. In vitro cell adhesion and proliferation on the nanocomposites occur without changes in viability and cytoskeleton formation. In vivo biocompatibility and biodegradability evaluation in rats has confirmed that the scaffolds promote the formation of novel blood vessels around the implantation sites. The scaffolds show excellent resorption within six weeks after implantation in rats. Neo-vascularization observed in newly formed connective tissue placed near the scaffold allows for the complete restoration of blood flow. These phenomena indicate that the halloysite-doped scaffolds are biocompatible as demonstrated both in vitro and in vivo. The chitosan-gelatine-agarose doped clay nanotube nanocomposite scaffolds fabricated in this work are promising candidates for tissue engineering applications.Porous biopolymer hydrogels doped at 3-6 wt% with 50 nm diameter/0.8 μm long natural clay nanotubes were produced without any cross-linkers using the freeze-drying method. The enhancement of mechanical strength (doubled pick load), higher water uptake and thermal properties in chitosan-gelatine-agarose hydrogels doped with halloysite was demonstrated. SEM and AFM imaging has shown the even distribution of nanotubes within the scaffolds. We used enhanced dark-field microscopy to visualise the distribution of halloysite nanotubes in the implantation area. In vitro cell adhesion and proliferation on the nanocomposites occur

  19. OIL WELL REMEDIATION IN CLAY AND WAYNE COUNTIES, IL

    SciTech Connect

    Peter L. Dakuras; Larry Stieber; Dick Young

    2003-07-09

    This is the second progress and final technical report of the remediation of abandoned wells in Clay and Wayne Counties in Illinois. The wells will be identified as the Routt No.3 and No.4 and the Bates Hosselton 1 and 2. Both sites have met all legal, financial and environmental requirements to drill and/or pump oil on both leases. We have also obtained all available information about both leases. All steps were taken to improve access roads, dig the necessary pits, and build the necessary firewalls. This progress and final technical report will address the remediation efforts as well as our results and conclusions.

  20. Biogenic smectite clay formation in subsurface granitic environments

    NASA Astrophysics Data System (ADS)

    Tuck, V.; Edyvean, R.; West, J.; Bateman, K.; Coombs, P.; Milodowski, A.

    2003-04-01

    Many bacteria and biofilms in groundwater environments are able to adsorb and accumulate soluble components from an aqueous environment and exert a strong influence on the attenuation and transport of a significant range of dissolved species including many pollutants. They can also act as catalysts or nucleation sites for authigenic mineral phases such as metal sulphides or complex silicates. The processes involved are not well defined, but appear to range from large-scale interactions altering bulk groundwater chemistry to very small-scale interactions involving geochemical and physical alterations within biofilms and at the mineral surface. The purpose of this research program is to investigate biologically-induced and unusually rapid formation of smectite and chlorite clays. The work expands on experiments conducted by the British Geological Survey designed to simulate rock-water/microbial interactions, radionuclide mobility and groundwater redox-buffering capacity in the vicinity of the Äspö Underground Research Laboratory (URL) in Sweden. Packed-columns were set up containing crushed Äspö granodiorite, saline groundwater (simulating Äspö’s) and either single or combined inoculations of two bacteria species isolated from the Äspö URL, an iron-reducer Shewanella putrefaciens and a sulphate-reducer Desulfovibrio aespoeensis. Flow was maintained at 12ml/day to mimic that in the Äspö region, and strict anaerobic/reducing conditions were maintained throughout the experiments. Results showed that the iron-reducing bacteria S. putrefaciens quickly attached to surfaces and formed extensive filamentous biofilm meshes across porespaces. Neoformed smectite and chlorite clays also appeared on or near the biofilaments along with a calcium sulphate precipitate. Both of these processes (clay formation and the production of a mesh-like biofilm) served to cause total blockage of the pores, rendering the aggregate impermeable and thus cutting off the flow of

  1. Evidence for a clay cycle on early Mars

    NASA Astrophysics Data System (ADS)

    Carter, J.; Poulet, F.

    2011-12-01

    Investigations of the morphology and mineralogy of early (Noachian) Mars have revealed ample evidence for liquid water-rock interactions at and near the surface, which may be the remnants of more habitable environments than today's. A number of valley networks [1], paleolakes [2], deltaic features [3,4] and sedimentary deposits [5] have been identified, suggesting that a surface and sub-surface hydrological system once existed on Mars. Mineralogical evidence includes the widespread detection of hydrated clays associated with Noachian terrains (e.g. [6,7]). The state of this early environment conducive to the formation of clays remains elusive as they are usually found in degraded morphological contexts and are to the first order decoupled in time and space with the fluvial morphology [8]. In particular, doubt remains whether the bulk of the aqueous alteration took place under the surface or as part of a surface hydrological system and thus implying stable liquid water over geological timescales. We present an overview of the early aqueous alteration on Mars through a combination of global mapping and regional investigations. We use NIR imaging spectrometer data from the spaceborne OMEGA and CRISM instruments [9,10] coupled with hi-resolution imaging data for context. We have detected over a thousand individual hydrated mineral exposures and investigated their composition and setting. We find that clays are found at a planetary scale, mostly in middle Noachian terrains and often associated with impact structures. Detailed investigation of the coupling between composition and context reveals that a clay cycle similar Earth's once existed on Mars, with all major settings: pedogenesis, transport, authigenic formation, diagenesis, metamorphism and hydrothermal alteration. We will present the major trends as inferred by global mapping and illustrate the different contexts through regional investigations. [1] Hynek et al., JGR 115, E09008 (2010). [2] Fassett et al

  2. Clays on Mars: Review of chemical and mineralogical evidence

    NASA Technical Reports Server (NTRS)

    Banin, Amos; Gooding, James L.

    1991-01-01

    Mafic igneous bedrock is inferred for Mars, based on spectrophotometric evidence for pyroxene (principally in optically dark areas of the globe) and the pyroxenite-peridotite petrology of shergottite nakhlite chassignite (SNC) meteorites. Visible and infrared spectra of reddish-brown surface fines (which dominate Martian bright areas) indicate ferric iron and compare favorably (though not uniquely) with spectra of palagonitic soils. Laboratory studies of SNC's and Viking Lander results support a model for Martian soil based on chemical weathering of mafic rocks to produce layer structured silicates (clay minerals), salts, and iron oxides.

  3. Organophilic clays as a tracer to determine Erosion processes

    NASA Astrophysics Data System (ADS)

    Mentler, A.; Strauss, P.; Schomakers, J.; Hann, S.; Köllensberger, G.; Ottner, F.

    2009-04-01

    In recent years the use of new tracing techniques to measure soil erosion has gained attention. Beside long time existing isotopic methods the use of rare earth elements has been reported. We wanted to contribute to the efforts of obtaining better methods for determination surface soil movement and tested a novel method using organophilic clays as a tracer for erosion related studies. At present tests to extract organophilic clays from soil have been performed successfully using an Industrial produced organophilic bentonite (Tixogel TVZ, Süd-Chemie) treated with quaternary ammonium surfactants. A liquid extraction method with barium ions (Ba2+) and methanol was used to extract the n-alkyl ammonium compounds from the inter crystal layers of the modified Bentonite. To increase extraction efficiency, an ultrasound device was used (UW 2200 Bandelin, 10.000 cycles per second, vibration amplitude 54 µm, sonification time of one minute). This procedure lead to a recovery rate of about 85% for the organophilic bentonite. This was clearly superior to alternative extraction methods such as acetonitrile in different mixing ratios. Quantification of the extracted surfactants was performed via high performance liquid chromatography - mass spectrometry (HPLC-MS, Agilent 1200 SL HPLC and 6220 time-of-flight MS). The mass spectra of this industrial produced organophilic clay mineral showed four different molecular masses (M+H+ of 304.30, 332.33, 360.36 and 388.39. The four substances could be separated by HPLC (20 x 2 mm Zorbax C18 reversed phase column, 0.5 mL/min isocratic flow with 90% acetonitrile and 0.1% formic acid in water, run time of 7 minutes). The linear working range of the method was 5 to 1000 µg/L, with a limit of quantification of 1 µg/L n-alkyl ammonium compound. All four compounds of the Tixogel were extracted with identical extraction efficiencies and are hence suitable for accurate quantification procedures. Next steps of the methodology to develop are the

  4. Mixed Waste Management Facility (MWMF) closure, Savannah River Plant: Clay cap test section construction report

    SciTech Connect

    Not Available

    1988-02-26

    This report contains appendix 2 for the Clay Cap Test Section Construction Report for the Mixed Waste Management Facility (MWMF) closure at the Savannah River Plant. The Clay Cap Test Program was conducted to evaluate the source, Laboratory permeability, and compaction characteristics representative of Kaolin clays from the aiken, South Carolina vicinity. Included in this report are daily field reports Nos. 1 to 54. (KJD)

  5. CHEMICAL AND MINERALOGICAL CHARACTERISTICS OF FRENCH GREEN CLAYS USED FOR HEALING

    PubMed Central

    Williams, Lynda B.; Haydel, Shelley E.; Giese, Rossman F.; Eberl, Dennis 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. PMID:19079803

  6. Clay slurry and engineered soils as containment technologies for remediation of contaminated sites

    SciTech Connect

    Williams, J.R.; Dudka, S.; Miller, W.P.; Johnson, D.O.

    1997-12-31

    Clay Slurry and Engineered Soils are containment technologies for remediation of waste disposal sites where leaching, groundwater plumes and surface runoff of contaminants are serious ecological hazards to adjacent environments. This technology is a patent-pending process which involves the use of conditioned clay materials mixed with sand and water to form a readily pourable suspension, a clay slurry, which is either placed into a trench barrier system or allowed to de-water to create Engineered Soils. The Engineered Soil forms a layer impervious to water and air, therefore by inhibiting both water and oxygen from penetrating through the soil the material. This material can be installed in layers and as a vertical barrier to create a surface barrier containment system. The clay percentage in the clay slurry and Engineered Soils varies depending on site characteristics and desired performance standards. For example Engineered Soils with 1-2% of clay (dry wt.) had a hydraulic conductivity (K) of 10{sup -8} to 10{sup -1} cm/sec. Tests of tailing materials from a kyanite and pyrite mine showed that the clay slurry was effective not only in reducing the permeability of the treated tailings, but also in decreasing their acidity due to the inherent alkalinity of the clay. The untreated tailings had pH values in the range of 2.4 - 3.1; whereas, the effluent from clay and tailings mixtures had pH values in a slightly alkaline range (7.7-7.9). Pug-mills and high volume slurry pumps can be readily adapted for use in constructing and placing caps and creating Engineered Soils. Moreover, material on site or from a local sand supply can be used to create clay slurries and engineered soils. Clay materials used in cap construction are likewise readily available commercially. As a result, the clay slurry system is very cost effective compared to other capping systems, including the commonly used High Density Polyethylene (HDPE) liner systems.

  7. Unraveling the antibacterial mode of action of a clay from the Colombian Amazon.

    PubMed

    Londono, Sandra Carolina; Williams, Lynda B

    2016-04-01

    Natural antibacterial clays can inhibit growth of human pathogens; therefore, understanding the antibacterial mode of action may lead to new applications for health. The antibacterial modes of action have shown differences based on mineralogical constraints. Here we investigate a natural clay from the Colombian Amazon (AMZ) known to the Uitoto natives as a healing clay. The physical and chemical properties of the AMZ clay were compared to standard reference materials: smectite (SWy-1) and kaolinite (API #5) that represent the major minerals in AMZ. We tested model Gram-negative (Escherichia coli ATCC #25922) and Gram-positive (Bacillus subtilis ATCC #6633) bacteria to assess the clay's antibacterial effectiveness against different bacterial types. The chemical and physical changes in the microbes were examined using bioimaging and mass spectrometry of clay digests and aqueous leachates. Results indicate that a single dose of AMZ clay (250 mg/mL) induced a 4-6 order of magnitude reduction in cell viability, unlike the reference clays that did not impact bacterial survival. AMZ clay possesses a relatively high specific surface area (51.23 m(2)/g) and much higher total surface area (278.82 m(2)/g) than the reference clays. In aqueous suspensions (50 mg clay/mL water), soluble metals are released and the minerals buffer fluid pH between 4.1 and 4.5. We propose that the clay facilitates chemical interactions detrimental to bacteria by absorbing nutrients (e.g., Mg, P) and potentially supplying metals (e.g., Al) toxic to bacteria. This study demonstrates that native traditional knowledge can direct scientific studies. PMID:26055454

  8. Role of Surface Interactions in the Synergizing Polymer/Clay Flame Retardant Properties

    SciTech Connect

    Pack, S.; Kashiwagi, T; Cao, C; Korach, C; Lewin, M; Rafailovich, M

    2010-01-01

    The absorption of resorcinol di(phenyl phosphate) (RDP) oligomers on clay surfaces has been studied in detail and is being proposed as an alternative method for producing functionalized clays for nanocomposite polymers. The ability of these clays to be exfoliated or intercalated in different homopolymers was investigated using both transmission electron microscopy and small-angle X-ray scattering results, compared with contact angle measurements on Langmuir-Blodgett clay monolayers, where the interfacial energies were used as predictors of the polymer/clay interactions. We found that the contact angle between PS/RDP clay monolayer substrates was {approx}2.5{sup o}, whereas the angle for polystyrene (PS)/Cloisite 20A clays substrates was {approx}32{sup o}, consistent with the large degree of exfoliation observed in PS for the RDP-coated clays. The interfacial activity of these clays was also measured, and we found that the RDP-coated clays segregated to the interfaces of PC/poly(styrene-co-acrylonitrile) blends, while they segregated into the poly(methyl methacrylate) (PMMA) domain of PS/PMMA blends. This morphology was explained in terms of the relative energy advantage in placing the RDP versus the Cloisite clays at the interfaces. Finally, we demonstrated the effects of the relative surface energies of the clays in segregating to the blend air interface when heated to high temperatures. The segregation was shown to affect the composition and mechanical properties of the resulting chars, which in turn could determine their flame retardant response.

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

    NASA Technical Reports Server (NTRS)

    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.

  10. CHEMICAL AND MINERALOGICAL CHARACTERISTICS OF FRENCH GREEN CLAYS USED FOR HEALING.

    PubMed

    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. PMID:19079803

  11. Breakdown of Clays by Ectomycorrhizal Fungi Through Changes in Oxidation State of Iron

    NASA Astrophysics Data System (ADS)

    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

  12. The Effect of 200 MPa Pressure on Specific Surface Area of Clay

    NASA Astrophysics Data System (ADS)

    Koszela-Marek, Ewa

    2015-02-01

    The paper presents the results of laboratory studies of the 200 MPa pressure effect on specific surface area of clay. The original high-pressure investigation stand was used for the pressure tests. Determination of the specific surface area was performed by the methylene blue adsorption method. The results of the specific surface area test were compared for non-pressurized clays and for clays pressured in a high-pressure chamber. It was found that the specific surface area of pressurized soil clearly increased. This shows that some microstructural changes take place in the soil skeleton of clays.

  13. Clay Cap Test Program for the Mixed Waste Management Facility closure at the Savannah River Site

    SciTech Connect

    Newell, J.W. , Inc., Charlotte, NC )

    1989-01-01

    A 58 acre low-level radioactive waste disposal facility at the Savannah River Site, a Department of Energy facility near Aiken, South Carolina, requires closure with a RCRA clay cap. A three-foot thick can requiring 300,000 cubic yards of local Tertiary Kaolin clay with an in-situ permeability of less than or equal to 1 {times} 10{sup -7} centimeters per second is to be constructed. The Clay Cap Test Program was conducted to evaluate the source, lab permeability, in-situ permeability, compaction characteristics, representative kaolin clays from the Aiken, SC vicinity. 11 refs., 8 figs., 1 tab.

  14. Incorporation of tramadol drug into Li-fluorohectorite clay: A preliminary study of a medical nanofluid

    NASA Astrophysics Data System (ADS)

    Valdés, L.; Hernández, D.; de Ménorval, L. Ch.; Pérez, I.; Altshuler, E.; Fossum, J. O.; Rivera, A.

    2016-07-01

    During the last years, clays have been increasingly explored as hosts for drugs. In the present paper, we have been able to host the non-steroidal anti-inflammatory drug, Tramadol, into the clay Li-fluorohectorite (Li-Fh). We preliminary evaluate its incorporation by means of UV spectroscopy and X ray diffraction. Our results indicate that the clay hosts the drug molecule in its interlayer space. We suggest a set of parameters to guarantee an efficient incorporation process. Future studies will concentrate on the release of the drug from the clay nanofluid.

  15. The influence of clay zones on land subsidence from groundwater pumping.

    PubMed

    Budhu, Muniram; Adiyaman, Ibrahim

    2013-01-01

    The objective of this article is to analyze the influence of clay zones on subsidence from groundwater pumping. Finite element analyses were conducted on a sand-only aquifer and a sand aquifer with two clay zones located at different distances from the well face. A model that accounts for recoverable and nonrecoverable strains was used to simulate the sand and clay. This model couples the groundwater flow with the stress-deformation response of the aquifer materials. Each aquifer was pumped from a single well for a period of 6 months, and then the groundwater level was lowered gradually to an elevation below the elevation of the clay zones and kept there for 10 years. The groundwater level was then raised gradually back to the original elevation over a period of 10 years. The results of the analyses show that the ground surface subsidence profile is strongly influenced by the presence of the clays zones. The ground surface sags where these clay zones are present resulting in a wavy ground surface profile. Subsidence continued when pumping is stopped, albeit at a much slower rate than during pumping, and when the groundwater level is below the elevation of the clay zones. Clay zones further away from the well face lag the subsidence of clay zones nearer the well face because of lower changes in hydrostatic head. Sags in ground surface subsidence profile from groundwater pumping are indicators of the presence of low hydraulic conductive geological materials. PMID:22536890

  16. Termites utilise clay to build structural supports and so increase foraging resources

    PubMed Central

    Oberst, Sebastian; Lai, Joseph C. S.; Evans, Theodore A.

    2016-01-01

    Many termite species use clay to build foraging galleries and mound-nests. In some cases clay is placed within excavations of their wooden food, such as living trees or timber in buildings; however the purpose for this clay is unclear. We tested the hypotheses that termites can identify load bearing wood, and that they use clay to provide mechanical support of the load and thus allow them to eat the wood. In field and laboratory experiments, we show that the lower termite Coptotermes acinaciformis, the most basal species to build a mound-nest, can distinguish unloaded from loaded wood, and use clay differently when eating each type. The termites target unloaded wood preferentially, and use thin clay sheeting to camouflage themselves while eating the unloaded wood. The termites attack loaded wood secondarily, and build thick, load-bearing clay walls when they do. The termites add clay and build thicker walls as the load-bearing wood is consumed. The use of clay to support wood under load unlocks otherwise unavailable food resources. This behaviour may represent an evolutionary step from foraging behaviour to nest building in lower termites. PMID:26854187

  17. Novel Organically Modified Core-Shell Clay for Epoxy Composites-"SOBM Filler 1".

    PubMed

    Iheaturu, Nnamdi Chibuike; Madufor, Innocent Chimezie

    2014-01-01

    Preparation of a novel organically modified clay from spent oil base drilling mud (SOBM) that could serve as core-shell clay filler for polymers is herein reported. Due to the hydrophilic nature of clay, its compatibility with polymer matrix was made possible through modification of the surface of the core clay sample with 3-aminopropyltriethoxysilane (3-APTES) compound prior to its use. Fourier transform infrared (FT-IR) spectroscopy was used to characterize clay surface modification. Electron dispersive X-ray diffraction (EDX) and scanning electron microscopy (SEM) were used to expose filler chemical composition and morphology, while electrophoresis measurement was used to examine level of filler dispersion. Results show an agglomerated core clay powder after high temperature treatment, while EDX analysis shows that the organically modified clay is composed of chemical inhomogeneities, wherein elemental compositions in weight percent vary from one point to the other in a probe of two points. Micrographs of the 3-APTES coupled SOBM core-shell clay filler clearly show cloudy appearance, while FT-IR indicates 25% and 5% increases in fundamental vibrations band at 1014 cm(-1) and 1435 cm(-1), respectively. Furthermore, 3-APTES coupled core-shell clay was used to prepare epoxy composites and tested for mechanical properties. PMID:27355022

  18. Effect of clay induced morphological transitions on behaviour of epoxy/PCL nanocomposite

    NASA Astrophysics Data System (ADS)

    Kelnar, Ivan; Rotrekl, Jakub

    2012-07-01

    Effect of organophilized montmorillonite (MMT) on structure formed by reactively induced phase separation (RIPS) and related properties of epoxy containing 5-30% polycaprolactone (PCL) was studied. The effect of clay is significant especially with supercritical PCL concentration, the radical change in morphology with 15% and 20% PCL leads to substantial improvement of mechanical behaviour. The main reason is change in epoxy phase parameters by clay, supporting its continuity. The mechanical behaviour is further influenced by change in coexisting phases composition due to reduced degree of phase separation caused by clay. The results indicate the potential of clay to tailor structure and properties of RIPS system with significant dynamic asymmetry of components.

  19. Use of swelling clays to reduce permeability and its potential application to nuclear waste repository sealing

    NASA Astrophysics Data System (ADS)

    Moore, D. E.; Morrow, C. A.; Byerlee, J. D.

    1982-09-01

    The injection of swelling-clay slurries into joints or faults at a deep-burial nuclear waste disposal site may result in significant permeability reductions for the effective containment of radioactive wastes. In an experiment conducted to illustrate the permeability change accompanying clay swelling, a coarse stone with interconnected pore spaces was injected with a clay-electrolyte slurry, modelling the pressure-grouting of a fractured repository rock. Subsequently, solutions with lower electrolyte concentrations were driven through the clay-filled stone, corresponding to migration of lower salinity ground-waters through the clay-grouted fracture. The initial injection procedure reduced the permeability of the stone from 1-10 darcies to 700 nanodarcies; the changes in solution composition decreased permeability by more than 2 additional orders of magnitude to 3 nanodarcies. For application at a nuclear waste repository, the electrolyte concentration of the injected clay slurry should be made higher than that of the ground-water in the host rock. Subsequent interaction of the ground-water with the clays would initiate swelling and create the additional, post-injection permeability reductions that may be important in preventing the escape of buried radioactive wastes. The measured permeability of the clay filling is considerably lower than that of cement tested for borehole plugging. Clays also have the advantage over cement and chemical grouts in that they are geologically stable at relatively low temperatures and have a high capacity for radionuclide adsorption.

  20. Direct visualization of clay microfabric signatures driving organic matter preservation in fine-grained sediment

    NASA Astrophysics Data System (ADS)

    Curry, Kenneth J.; Bennett, Richard H.; Mayer, Lawrence M.; Curry, Ann; Abril, Maritza; Biesiot, Patricia M.; Hulbert, Matthew H.

    2007-04-01

    We employed direct visualization of organic matter (OM) sequestered by microfabric signatures in organo-clay systems to study mechanisms of OM protection. We studied polysaccharides, an abundant class of OM in marine sediments, associated with the nano- and microfabric of clay sediment using a novel application of transmission electron microscopy, histochemical staining (periodic acid-thiosemicarbazide-silver proteinate), and enzymatic digestion techniques. We used two experimental organo-clay sediment environments. First, laboratory-consolidated sediment with 10% chitin (w/w) added was probed for chitin before and after digestion with chitinase. Second, fecal pellets from the polychaete Heteromastus filiformis were used as a natural environment rich in clay and polysaccharides. Sections of this material were probed with silver proteinate for polysaccharides before and after digestion with a mixture of enzymes (amylase, cellulase, chitinase, dextranase, and pectinase). In both environments, chitin or other polysaccharides were found within pores, bridging clay domains, and attached to clay surfaces in undigested samples. Digested samples showed chitin or polysaccharides more closely associated with clay surfaces and in small pores. Our results imply protective roles for both sorption to clay surfaces and encapsulation within clay microfabric signatures.

  1. Novel Organically Modified Core-Shell Clay for Epoxy Composites—“SOBM Filler 1”

    PubMed Central

    Iheaturu, Nnamdi Chibuike; Madufor, Innocent Chimezie

    2014-01-01

    Preparation of a novel organically modified clay from spent oil base drilling mud (SOBM) that could serve as core-shell clay filler for polymers is herein reported. Due to the hydrophilic nature of clay, its compatibility with polymer matrix was made possible through modification of the surface of the core clay sample with 3-aminopropyltriethoxysilane (3-APTES) compound prior to its use. Fourier transform infrared (FT-IR) spectroscopy was used to characterize clay surface modification. Electron dispersive X-ray diffraction (EDX) and scanning electron microscopy (SEM) were used to expose filler chemical composition and morphology, while electrophoresis measurement was used to examine level of filler dispersion. Results show an agglomerated core clay powder after high temperature treatment, while EDX analysis shows that the organically modified clay is composed of chemical inhomogeneities, wherein elemental compositions in weight percent vary from one point to the other in a probe of two points. Micrographs of the 3-APTES coupled SOBM core-shell clay filler clearly show cloudy appearance, while FT-IR indicates 25% and 5% increases in fundamental vibrations band at 1014 cm−1 and 1435 cm−1, respectively. Furthermore, 3-APTES coupled core-shell clay was used to prepare epoxy composites and tested for mechanical properties. PMID:27355022

  2. Influence of Clay Content, Mineralogy and Fabric On Radar Frequency Response of Aquifer Materials

    NASA Astrophysics Data System (ADS)

    West, L. J.; Handley, K.

    High frequency electromagnetic methods such as ground penetrating radar (GPR) and time domain reflectometry (TDR) are widely employed to measure water saturation in the vadose zone and water filled porosity in the saturated zone. However, previous work has shown that radar frequency dielectric properties are strongly influenced by clay as well as by water content. They have also shown that that the dielectric response of clay minerals is strongly frequency dependent, and that even a small proportion of clay such as that present in many sandstone aquifers can have a large effect at typi- cal GPR frequencies (around 100MHz). Hence accurate water content/porosity deter- mination requires clay type and content to be taken into account. Reported here are dielectric measurements on clay-sand mixtures, aimed at investigating the influence of clay mineralogy, particle shape, and the geometrical arrangement of the mixture constituents on GPR and TDR response. Dielectric permittivity (at 50-1000MHz) was measured for mixtures of Ottawa Sand and various clay minerals or clay size quartz rock flour, using a specially constructed dielectric cell. Both homogeneous and layered mixtures were tested. The influence of pore water salinity, clay type, and particle arrangement on the dielectric response is interpreted in terms of dielectric dispersion mechanisms. The appropriateness of var- ious dielectric mixing rules such as the Complex Refractive Index Method (CRIM) for determination of water content or porosity from field GPR and TDR data are dis- cussed.

  3. Termites utilise clay to build structural supports and so increase foraging resources.

    PubMed

    Oberst, Sebastian; Lai, Joseph C S; Evans, Theodore A

    2016-01-01

    Many termite species use clay to build foraging galleries and mound-nests. In some cases clay is placed within excavations of their wooden food, such as living trees or timber in buildings; however the purpose for this clay is unclear. We tested the hypotheses that termites can identify load bearing wood, and that they use clay to provide mechanical support of the load and thus allow them to eat the wood. In field and laboratory experiments, we show that the lower termite Coptotermes acinaciformis, the most basal species to build a mound-nest, can distinguish unloaded from loaded wood, and use clay differently when eating each type. The termites target unloaded wood preferentially, and use thin clay sheeting to camouflage themselves while eating the unloaded wood. The termites attack loaded wood secondarily, and build thick, load-bearing clay walls when they do. The termites add clay and build thicker walls as the load-bearing wood is consumed. The use of clay to support wood under load unlocks otherwise unavailable food resources. This behaviour may represent an evolutionary step from foraging behaviour to nest building in lower termites. PMID:26854187

  4. Clay-shoveler's fracture during indoor rock climbing.

    PubMed

    Kaloostian, Paul E; Kim, Jennifer E; Calabresi, Peter A; Bydon, Ali; Witham, Timothy

    2013-03-01

    Indoor rock climbing is becoming more popular for people of all ages. Despite the tremendous interest in this competitive sport, participants are made aware of the dangers associated with participating. The authors present the first reported case of a clay-shoveler's fracture at the T1 spinous process during indoor rock climbing. They describe the management and natural history of this fracture and discuss management strategies for this increasingly popular recreational sport.A 14-year-old competitive indoor rock climber presented with acute-onset midline thoracic pain at T1 while indoor rock climbing. He reported no recent falls or trauma but stated that the pain came on abruptly while rock climbing. On examination, he was neurologically intact except for significant tenderness to palpation at the T1 spinous process. Magnetic resonance imaging demonstrated a minimally displaced T1 spinous process fracture with evidence of significant surrounding muscular edema, suggesting an acute fracture. He was treated conservatively with anti-inflammatory drugs, complete climbing restriction, and rest. He continued to have focal upper back pain at the level of the fracture over the next 4 months. He was unable to climb for 4 months until his pain resolved after conservative treatment of climbing restriction, pain control, and rest.This is the first documented case of a clay-shoveler's fracture sustained in a pediatric patient directly attributable to indoor rock climbing. PMID:23464962

  5. Laboratory modeling of laterally-loaded drilled shafts in clay

    SciTech Connect

    Mayne, P.W.; Kulhawy, F.H.; Trautmann, C.H.

    1995-12-01

    The behavior of free-head rigid drilled shafts under static and cyclic lateral and moment loading was investigated using laboratory models in relatively large test chambers. This testing program represents perhaps one of the first larger-scale laboratory test series to utilize cast-in-place concrete shafts in consolidated and prestressed cohesive soil deposits for realistic simulation of prototype drilled shafts in clays. The construction procedure incorporated the actual effects of concrete curing and soil/concrete interface roughness, and the soil-deposit preparation included the characteristic anisotropy and overconsolidation associated with natural clays. A total of 28 cylindrical shafts having diameters of 51, 89, and 175 mm (2.0, 3.5, and 6.9 in.) and depth-do-diameter (D/B) ratios of 3--8 were constructed and tested. Many of the shafts were instrumented with total stress cells and pore-water stress transducers to permit both total and effective stress measurements during the load testing. The results of the lateral and moment load tests indicated a high degree of nonlinearity in the monotonic static load-displacement response, but it can be represented adequately by a hyperbola. This hyperbola also provides a reference backbone curve for the cyclic loading behavior.

  6. Stress-Induced Permeability Anisotropy of Resedimented Boston Blue Clay

    NASA Astrophysics Data System (ADS)

    Adams, A. L.; Germaine, J. T.; Flemings, P. B.

    2011-12-01

    Significant permeability anisotropy, defined as the ratio of horizontal to vertical permeability, can develop in a homogenous material due to one dimensional compression. In Resedimented Boston Blue Clay (RBBC), a low plasticity glacio-marine illitic clay, the permeability anisotropy increases from 1.22 to 1.85 as the porosity decreases from 0.5 to 0.37. The permeability decreases by greater than one order of magnitude over this porosity range, ranging from 7.5 x 10-17 m2 to 3.9 x 10-18 m2 vertically and from 9.1 x 10-17 m2 to 7.2 x 10-18 m2 horizontally. SEM images, taken at different orientations and stress levels, reveal that pores become increasingly elongate perpendicular to the maximum (vertical) loading direction as stress is increased. We interpret that rotation of platy materials creates this fabric. To make these measurements, a new method to measure the permeability anisotropy using cubic specimens was developed. In addition, we correct for test sequence bias and minimize scatter in the data set to produce a well defined permeability anisotropy vs. porosity trend. A better understanding of the evolution of permeability anisotropy during sediment burial is important for understanding a range of transport processes in the subsurface.

  7. Ion Exchange Resin and Clay Vitrification by Plasma Discharges

    NASA Astrophysics Data System (ADS)

    Díaz A., Laura V.; Pacheco S., Joel O.; Pacheco P., Marquidia; Monroy G., Fabiola; Emeterio H., Miguel; Ramos F., Fidel

    2006-12-01

    The lack of treatment of a low and intermediate level radioactive waste (LILRW) lead us to propose a vitrification process based on a plasma discharge; this technique incorporates LILRW into a matrix glass composed of ceramic clays material. The Mexican Institute of Nuclear Research (ININ), uses an ion exchange resin IRN 150 (styrene-divinilbence copolymer) in the TRIGA MARK III nuclear reactor. The principal objective of this resin is to absorb particles containing heavy metals and low-level radioactive particles. Once the IRN 150 resin filter capacity has been exceeded, it should be replaced and treated as LILRW. In this work, a transferred plasma system was realized to vitrify this resin taking advantage of its high power density, enthalpy and chemical reactivity as well as its rapid quenching and high operation temperatures. In order to characterize the morphological structure of these clay samples, Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD) and Thermogravimetric analysis (TGA) techniques were applied before and after the plasma treatment.

  8. Ion Exchange Resin and Clay Vitrification by Plasma Discharges

    SciTech Connect

    Diaz A, Laura V.

    2006-12-04

    The lack of treatment of a low and intermediate level radioactive waste (LILRW) lead us to propose a vitrification process based on a plasma discharge; this technique incorporates LILRW into a matrix glass composed of ceramic clays material. The Mexican Institute of Nuclear Research (ININ), uses an ion exchange resin IRN 150 (styrene-divinilbence copolymer) in the TRIGA MARK III nuclear reactor. The principal objective of this resin is to absorb particles containing heavy metals and low-level radioactive particles. Once the IRN 150 resin filter capacity has been exceeded, it should be replaced and treated as LILRW. In this work, a transferred plasma system was realized to vitrify this resin taking advantage of its high power density, enthalpy and chemical reactivity as well as its rapid quenching and high operation temperatures. In order to characterize the morphological structure of these clay samples, Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD) and Thermogravimetric analysis (TGA) techniques were applied before and after the plasma treatment.

  9. Ion exchange and surface charge on montmorillonite clay

    SciTech Connect

    Sperry, J.M.; Peirce, J.J.

    1999-05-01

    An ion-exchange model originally developed for pure oxides prepared in the laboratory is extended to study of ion exchange and surface charge on a naturally occurring montmorillonite clay. The range of surface charges measured for montmorillonite with various electrolyte solutions and clay pretreatments is within the range of those measured for a wide variety of oxides prepared in the laboratory, including MnO{sub 2}-IC1, MnO{sub 2}-IC12, MnO{sub 2}-IC22, titanium dioxide, ferric oxide, and aluminum oxide. In addition, fitted parameter values for lateral interaction constants and equilibrium constants for the acid sites that characterize ion exchange on montmorillonite are on the same order of magnitude as those obtained for pure oxides. Surface charge of montmorillonite in sodium nitrate solution is measured to be approximately 15 to 25% greater than that measured between a pH of 4 and 9 in calcium chloride solution. This difference is attributed to the greater charge on the calcium (2{sup +}) ion; thus, its stronger electrostatic attraction to the acid hydroxyl site. An order of magnitude change in solids concentration (C{sub p}) can lead to a difference in measured net surface charge density of the same oxide sample of several orders of magnitude. This difference increases at higher pH, indicating the importance of reporting the corresponding C{sub p} at which experiments are conducted.

  10. Diagenesis and clay mineral formation at Gale Crater, Mars

    SciTech Connect

    Bridges, J. C.; Schwenzer, S. P.; Leveille, R.; Westall, F.; Wiens, R. C.; Mangold, N.; Bristow, T.; Edwards, P.; Berger, G.

    2015-01-18

    The Mars Science Laboratory rover Curiosity found host rocks of basaltic composition and alteration assemblages containing clay minerals at Yellowknife Bay, Gale Crater. On the basis of the observed host rock and alteration minerals, we present results of equilibrium thermochemical modeling of the Sheepbed mudstones of Yellowknife Bay in order to constrain the formation conditions of its secondary mineral assemblage. Building on conclusions from sedimentary observations by the Mars Science Laboratory team, we assume diagenetic, in situ alteration. The modeling shows that the mineral assemblage formed by the reaction of a CO₂-poor and oxidizing, dilute aqueous solution (Gale Portage Water) in an open system with the Fe-rich basaltic-composition sedimentary rocks at 10–50°C and water/rock ratio (mass of rock reacted with the starting fluid) of 100–1000, pH of ~7.5–12. Model alteration assemblages predominantly contain phyllosilicates (Fe-smectite, chlorite), the bulk composition of a mixture of which is close to that of saponite inferred from Chemistry and Mineralogy data and to that of saponite observed in the nakhlite Martian meteorites and terrestrial analogues. To match the observed clay mineral chemistry, inhomogeneous dissolution dominated by the amorphous phase and olivine is required. We therefore deduce a dissolving composition of approximately 70% amorphous material, with 20% olivine, and 10% whole rock component.

  11. Diagenesis and clay mineral formation at Gale Crater, Mars

    DOE PAGESBeta

    Bridges, J. C.; Schwenzer, S. P.; Leveille, R.; Westall, F.; Wiens, R. C.; Mangold, N.; Bristow, T.; Edwards, P.; Berger, G.

    2015-01-18

    The Mars Science Laboratory rover Curiosity found host rocks of basaltic composition and alteration assemblages containing clay minerals at Yellowknife Bay, Gale Crater. On the basis of the observed host rock and alteration minerals, we present results of equilibrium thermochemical modeling of the Sheepbed mudstones of Yellowknife Bay in order to constrain the formation conditions of its secondary mineral assemblage. Building on conclusions from sedimentary observations by the Mars Science Laboratory team, we assume diagenetic, in situ alteration. The modeling shows that the mineral assemblage formed by the reaction of a CO₂-poor and oxidizing, dilute aqueous solution (Gale Portage Water)more » in an open system with the Fe-rich basaltic-composition sedimentary rocks at 10–50°C and water/rock ratio (mass of rock reacted with the starting fluid) of 100–1000, pH of ~7.5–12. Model alteration assemblages predominantly contain phyllosilicates (Fe-smectite, chlorite), the bulk composition of a mixture of which is close to that of saponite inferred from Chemistry and Mineralogy data and to that of saponite observed in the nakhlite Martian meteorites and terrestrial analogues. To match the observed clay mineral chemistry, inhomogeneous dissolution dominated by the amorphous phase and olivine is required. We therefore deduce a dissolving composition of approximately 70% amorphous material, with 20% olivine, and 10% whole rock component.« less

  12. Experimental investigations of the wettability of clays and shales

    NASA Astrophysics Data System (ADS)

    Borysenko, Artem; Clennell, Ben; Sedev, Rossen; Burgar, Iko; Ralston, John; Raven, Mark; Dewhurst, David; Liu, Keyu

    2009-07-01

    Wettability in argillaceous materials is poorly understood, yet it is critical to hydrocarbon recovery in clay-rich reservoirs and capillary seal capacity in both caprocks and fault gouges. The hydrophobic or hydrophilic nature of clay-bearing soils and sediments also controls to a large degree the movement of spilled nonaqueous phase liquids in the subsurface and the options available for remediation of these pollutants. In this paper the wettability of hydrocarbons contacting shales in their natural state and the tendencies for wettability alteration were examined. Water-wet, oil-wet, and mixed-wet shales from wells in Australia were investigated and were compared with simplified model shales (single and mixed minerals) artificially treated in crude oil. The intact natural shale samples (preserved with their original water content) were characterized petrophysically by dielectric spectroscopy and nuclear magnetic resonance, plus scanning electron, optical and fluorescence microscopy. Wettability alteration was studied using spontaneous imbibition, pigment extraction, and the sessile drop method for contact angle measurement. The mineralogy and chemical compositions of the shales were determined by standard methods. By studying pure minerals and natural shales in parallel, a correlation between the petrophysical properties, and wetting behavior was observed. These correlations may potentially be used to assess wettability in downhole measurements.

  13. Heteroaggregation of engineered nanoparticles and kaolin clays in aqueous environments.

    PubMed

    Wang, Hongtao; Dong, Ya-nan; Zhu, Miao; Li, Xiang; Keller, Arturo A; Wang, Tao; Li, Fengting

    2015-09-01

    The increasing and wide use of nanoparticles (NPs), including TiO2 and Ag NPs, have raised concerns due to their potential toxicity and environmental impacts. Kaolin is a very common mineral in aquatic systems, and there is a very high probability that nanoparticles (NPs) will interact with these clay minerals. We studied the effect of kaolin particles on the aggregation of NPs under different conditions, including the role of pH, ionic strength (IS), and humic acid (HA). We show that kaolin reduces the energy barrier and the Critical Coagulation Concentration (CCC) at pH 4. At pH 8, even though the energy barrier of the system without kaolin increases, kaolin promotes NP aggregation via heteroaggregation. When IS is equal to or greater than the CCC, on the one hand HA promotes aggregation of TiO2 NPs, but on the other hand HA decreases the rate of Ag NP aggregation because the existence of a surface coating may limit the adsorption of HA on these Ag NPs. In addition, the presence of HA increases the energy barrier and the CCC of the binary system (kaolin + NPs). Thus, the complex interactions of clay, NPs, IS, pH, and HA concentration determine the colloidal stability of the NPs. We find that kaolin is a potential coagulant for removal of NPs that behave like Ag and TiO2. PMID:26001279

  14. Diagenesis and clay mineral formation at Gale Crater, Mars

    PubMed Central

    Bridges, J C; Schwenzer, S P; Leveille, R; Westall, F; Wiens, R C; Mangold, N; Bristow, T; Edwards, P; Berger, G

    2015-01-01

    The Mars Science Laboratory rover Curiosity found host rocks of basaltic composition and alteration assemblages containing clay minerals at Yellowknife Bay, Gale Crater. On the basis of the observed host rock and alteration minerals, we present results of equilibrium thermochemical modeling of the Sheepbed mudstones of Yellowknife Bay in order to constrain the formation conditions of its secondary mineral assemblage. Building on conclusions from sedimentary observations by the Mars Science Laboratory team, we assume diagenetic, in situ alteration. The modeling shows that the mineral assemblage formed by the reaction of a CO2-poor and oxidizing, dilute aqueous solution (Gale Portage Water) in an open system with the Fe-rich basaltic-composition sedimentary rocks at 10–50°C and water/rock ratio (mass of rock reacted with the starting fluid) of 100–1000, pH of ∽7.5–12. Model alteration assemblages predominantly contain phyllosilicates (Fe-smectite, chlorite), the bulk composition of a mixture of which is close to that of saponite inferred from Chemistry and Mineralogy data and to that of saponite observed in the nakhlite Martian meteorites and terrestrial analogues. To match the observed clay mineral chemistry, inhomogeneous dissolution dominated by the amorphous phase and olivine is required. We therefore deduce a dissolving composition of approximately 70% amorphous material, with 20% olivine, and 10% whole rock component. PMID:26213668

  15. Orientation of charged clay nanotubes in evaporating droplet meniscus.

    PubMed

    Zhao, Yafei; Cavallaro, Giuseppe; Lvov, Yuri

    2015-02-15

    During drying, an aqueous suspension of strongly charged halloysite clay nanotubes concentrates at the edge of the droplet ("coffee-ring" effect) which provides alignment of the tubes along the liquid-substrate contact line. First, the surface charge of the nanotubes was enhanced by polyanion adsorption inside of the lumen to compensate for the internal positive charges. This increased the magnitude of the ξ-potential of the tubes from -36 to -81 mV and stabilized the colloids. Then, colloidal halloysite was dropped onto the substrate, dried at 65 °C and after a concentration of ∼0.05 mg mL(-1) was reached, the alignment of nanotubes occurred starting from the droplet edges. The process was described with Onsager's theory, in which longer nanorods, which have higher surface charge, give better ordering after a critical concentration is reached. This study indicates a new application of halloysite clay nanotubes in polymeric composites with anisotropic properties, microchannel orientation, and production of coatings with aligned nanotubes. PMID:25460691

  16. Thoron and thoron progeny measurements in German clay houses.

    PubMed

    Gierl, S; Meisenberg, O; Feistenauer, P; Tschiersch, J

    2014-07-01

    In recent years, elevated thoron concentrations were found in houses built of unfired clay. In this study experiments were carried out in 17 traditional and modern clay houses in Germany to obtain an overview of indoor thoron in such houses. Long-term measurements over an 8-week period were performed using a newly developed Unattended Battery-Operated Progeny Measurement Device (UBPM) for measuring thoron progeny. This instrument uses a high-voltage electric field to precipitate radon and thoron progeny on nuclear track detectors. Additional active and passive measurements of radon, thoron and their progeny were performed. The equilibrium equivalent thoron concentration was found to be between 2 and 10 Bq m(-3). Gas concentrations were found to be between 20 and 160 Bq m(-3) for radon and between 10 and 90 Bq m(-3) for thoron 20 cm from the wall. The thoron exposure contributes significantly to the inhalation dose of the dwellers (0.6-4 mSv a(-1)). PMID:24743764

  17. Poly (lactic acid) (PLA)/clay/wood nanocomposites

    NASA Astrophysics Data System (ADS)

    Meng, Qingkai

    Poly (lactic acid) (PLA) is a promising substitute for conventional petroleum-based polymer materials as a result of its environmentally benign quality and suitable physical properties. However, there are also problems associated with properties, such as brittleness, low heat deflection temperature, low melt viscosity, as well as cost that prevent wide-range applications of PLA. This work reports on melt extrusion preparation of PLA/clay/wood nanocomposites involving various compatibilizers, resulting in remarkable improvements in mechanical as well as in thermal material properties. In particular, the tensile and flexural moduli of PLA/clay/wood nanocomposites with 30 wt. % wood flour and 5 wt. % nanoclay respectively increased from 3.75 to 7.08 GPa and from 3.83 to 6.01 GPa compared to neat PLA. The thermal decomposition temperature improved by about 10°C compared to that of PLA/wood composites. A mathematical model was developed based on Eshelby's equivalent inclusion method and Mori-Tanaka's background analysis to successfully predict longitudinal elastic moduli of complex structured nanocomposite materials.

  18. The Use of Clay-Polymer Nanocomposites in Wastewater Pretreatment

    PubMed Central

    Rytwo, Giora

    2012-01-01

    Some agricultural effluents are unsuitable for discharge into standard sewage-treatment plants: their pretreatment is necessary to avoid clogging of the filtering devices by colloidal matter. The colloidal stability of the effluents is mainly due to mutual repulsive forces that keep charged particles in suspension. Pretreatment processes are based on two separate stages: (a) neutralization of the charges (“coagulation”) and (b) bridging between several small particles to form larger aggregates that sink, leaving clarified effluent (“flocculation”). The consequent destabilization of the colloidal suspension lowers total suspended solids (TSSs), turbidity, and other environmental quality parameters, making the treatments that follow more efficient. Clay-based materials have been widely used for effluent pretreatment and pollutant removal. This study presents the use of nanocomposites, comprised of an anchoring particle and a polymer, as “coagoflocculants” for the efficient and rapid reduction of TSS and turbidity in wastewater with a high organic load. The use of such particles combines the advantages of coagulant and flocculant by neutralizing the charge of the suspended particles while bridging between them and anchoring them to a denser particle (the clay mineral), enhancing their precipitation. Very rapid and efficient pretreatment is achieved in one single treatment step. PMID:22454607

  19. Effects of leachate on geotechnical characteristics of sandy clay soil

    NASA Astrophysics Data System (ADS)

    Harun, N. S.; Ali, Z. Rahman; Rahim, A. S.; Lihan, T.; Idris, R. M. W.

    2013-11-01

    Leachate is a hazardous liquid that poses negative impacts if leaks out into environments such as soil and ground water systems. The impact of leachate on the downgraded quality in terms of chemical characteristic is more concern rather than the physical or mechanical aspect. The effect of leachate on mechanical behaviour of contaminated soil is not well established and should be investigated. This paper presents the preliminary results of the effects of leachate on the Atterberg limit, compaction and shear strength of leachate-contaminated soil. The contaminated soil samples were prepared by mixing the leachate at ratiosbetween 0% and 20% leachate contents with soil samples. Base soil used was residual soil originated from granitic rock and classified as sandy clay soil (CS). Its specific gravity ranged between 2.5 and 2.64 with clay minerals of kaolinite, muscovite and quartz. The field strength of the studied soil ranged between 156 and 207 kN/m2. The effects of leachate on the Atterberg limit clearly indicated by the decrease in liquid and plastic limit values with the increase in the leachate content. Compaction tests on leachate-contaminated soil caused the dropped in maximum dry density, ρdry and increased in optimum moisture content, wopt when the amount of leachate was increased between 0% and 20%. The results suggested that leachate contamination capable to modify some geotechnical properties of the studied residual soils.

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

    NASA Technical Reports Server (NTRS)

    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.