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Sample records for modeling clay based

  1. Numerical verification of similar Cam-clay model based on generalized potential theory

    Institute of Scientific and Technical Information of China (English)

    钟志辉; 杨光华; 傅旭东; 温勇; 张玉成

    2014-01-01

    From the mathematical principles, the generalized potential theory can be employed to create constitutive model of geomaterial directly. The similar Cam-clay model, which is created based on the generalized potential theory, has less assumptions, clearer mathematical basis, and better computational accuracy. Theoretically, it is more scientific than the traditional Cam-clay models. The particle flow code PFC3D was used to make numerical tests to verify the rationality and practicality of the similar Cam-clay model. The verification process was as follows: 1) creating the soil sample for numerical test in PFC3D, and then simulating the conventional triaxial compression test, isotropic compression test, and isotropic unloading test by PFC3D; 2) determining the parameters of the similar Cam-clay model from the results of above tests; 3) predicting the sample’s behavior in triaxial tests under different stress paths by the similar Cam-clay model, and comparing the predicting results with predictions by the Cam-clay model and the modified Cam-clay model. The analysis results show that the similar Cam-clay model has relatively high prediction accuracy, as well as good practical value.

  2. Validation of water sorption-based clay prediction models for calcareous soils

    DEFF Research Database (Denmark)

    Arthur, Emmanuel; Razzaghi, Fatemeh; Moosavi, Ali

    2017-01-01

    Soil particle size distribution (PSD), particularly the active clay fraction, mediates soil engineering, agronomic and environmental functions. The tedious and costly nature of traditional methods of determining PSD prompted the development of water sorption-based models for determining the clay...

  3. Constitutive model for overconsolidated clays

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Based on the relationships between the Hvorslev envelope,the current yield sur-face and the reference yield surface,a new constitutive model for overconsolidated clays is proposed. It adopts the unified hardening parameter,to which the potential failure stress ratio and the characteristic state stress ratio are introduced. The model can describe many characteristics of overconsolidated clays,including stress-strain relationships,strain hardening and softening,stress dilatancy,and stress path dependency. Compared with the Cam-clay model,the model only re-quires one additional soil parameter which is the slope of the Hvorslev envelope. Comparisons with data from triaxial drained compression tests for Fujinomori clay show that the proposed model can rationally describe overconsolidated properties. In addition,the model is also used to predict the stress-strain relationship in the isotropic consolidation condition and the stress paths in the undrained triaxial compression tests.

  4. Long-term modeling of glass waste in portland cement- and clay-based matrices

    Energy Technology Data Exchange (ETDEWEB)

    Stockman, H.W.; Nagy, K.L. [Sandia National Labs., Albuquerque, NM (United States); Morris, C.E. [Wollongong Univ., NSW (Australia). Dept. of Civil and Mining Engineering

    1995-12-01

    A set of ``templates`` was developed for modeling waste glass interactions with cement-based and clay-based matrices. The templates consist of a modified thermodynamic database, and input files for the EQ3/6 reaction path code, containing embedded rate models and compositions for waste glass, cement, and several pozzolanic materials. Significant modifications were made in the thermodynamic data for Th, Pb, Ra, Ba, cement phases, and aqueous silica species. It was found that the cement-containing matrices could increase glass corrosion rates by several orders of magnitude (over matrixless or clay matrix systems), but they also offered the lowest overall solubility for Pb, Ra, Th and U. Addition of pozzolans to cement decreased calculated glass corrosion rates by up to a factor of 30. It is shown that with current modeling capabilities, the ``affinity effect`` cannot be trusted to passivate glass if nuclei are available for precipitation of secondary phases that reduce silica activity.

  5. Acid-base properties of 2:1 clays. I. Modeling the role of electrostatics.

    Science.gov (United States)

    Delhorme, Maxime; Labbez, Christophe; Caillet, Céline; Thomas, Fabien

    2010-06-15

    We present a theoretical investigation of the titratable charge of clays with various structural charge (sigma(b)): pyrophyllite (sigma(b) = 0 e x nm(-2)), montmorillonite (sigma(b) = -0.7 e x nm(-2)) and illite (sigma(b) = -1.2 e x nm(-2)). The calculations were carried out using a Monte Carlo method in the Grand Canonical ensemble and in the framework of the primitive model. The clay particle was modeled as a perfect hexagonal platelet, with an "ideal" crystal structure. The only fitting parameters used are the intrinsic equilibrium constants (pK(0)) for the protonation/deprotonation reactions of the broken-bond sites on the lateral faces of the clay particles, silanol, =SiO(-) + H(+) --> =SiOH, and aluminol, =AlO(-1/2) + H(+) --> =AlOH(+1/2). Simulations are found to give a satisfactory description of the acid-base titration of montmorillonite without any additional fitting parameter. In particular, combining the electrostatics from the crystal substitutions with ionization constants, the simulations satisfactorily catch the shift in the titration curve of montmorillonite according to the ionic strength. Change in the ionic strength modulates the screening of the electrostatic interactions which results in this shift. Accordingly, the PZNPC is found to shift toward alkaline pH upon increasing the permanent basal charge. Unlike previous mean field model results, a significant decrease in PZNPC values is predicted in response to stack formation. Finally, the mean field approach is shown to be inappropriate to study the acid-base properties of clays.

  6. An elasto-plastic constitutive model of moderate sandy clay based on BC-RBFNN

    Institute of Scientific and Technical Information of China (English)

    彭相华; 王智超; 罗涛; 余敏; 罗迎社

    2008-01-01

    Application research of neural networks to geotechnical engineering has become a hotspot nowadays.General model may not reach the predicting precision in practical application due to different characteristics in different fields.In allusion to this,an elasto-plastic constitutive model based on clustering radial basis function neural network(BC-RBFNN) was proposed for moderate sandy clay according to its properties.Firstly,knowledge base was established on triaxial compression testing data;then the model was trained,learned and emulated using knowledge base;finally,predicting results of the BC-RBFNN model were compared and analyzed with those of other intelligent model.The results show that the BC-RBFNN model can alter the training and learning velocity and improve the predicting precision,which provides possibility for engineering practice on demanding high precision.

  7. Calculation of the debris flow concentration based on clay content

    Institute of Scientific and Technical Information of China (English)

    CHEN Ningsheng; CUI Peng; LIU Zhonggang; WEI Fangqiang

    2003-01-01

    The debris flow clay content has very tremendous influence on its concentration (γC). It is reported that the concentration can be calculated by applying the relative polynomial based on the clay content. Here one polynomial model and one logarithm model to calculate the concentration based on the clay content for both the ordinary debris flow and viscous debris flow are obtained. The result derives from the statistics and analysis of the relationship between the debris flow concentrations and clay content in 45 debris flow sites located in the southwest of China. The models can be applied for the concentration calculation to those debris flows that are impossible to observe. The models are available to calculate the debris flow concentration, the principles of which are in the clay content affecting on the debris flow formation, movement and suspending particle diameter. The mechanism of the relationship of the clay content and concentration is clear and reliable. The debris flow is usually of micro-viscous when the clay content is low (<3%), by analyzing the developing tendency on the basics of the relationship between the clay content and debris flow concentration. Indeed, the less the clay content, the less the concentration for most debris flows. The debris flow tends to become the water rock flow or the hyperconcentrated flow with the clay content decrease. Through statistics it is apt to transform the soil into the viscous debris flow when the clay content of ranges is in 3%-18%. Its concentration increases with the increasing of the clay content when the clay content is between 5% and 10%. But the value decreases with the increasing of the clay content when the clay content is between 10% and 18%. It is apt to transform the soil into the mudflow, when the clay content exceeds 18%. The concentration of the mudflow usually decreases with the increase of the clay content, and this developing tendency reverses to that of the micro-viscous debris flow. There is

  8. Sectioning Clay Models Makes Anatomy & Development Tangible

    Science.gov (United States)

    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…

  9. Modeling of calcination of single kaolinitic clay particle

    DEFF Research Database (Denmark)

    Gebremariam, Abraham Teklay; Yin, Chungen; Rosendahl, Lasse

    The present work aims at modeling of the calcination (dehydroxylation) process of clay particles, specifically kaolinite, and its thermal transformation. For such purpose, 1D single particle calcination model was developed based on the concept of shrinking core model to assess the dehydroxylation...

  10. Modeling of calcination of single kaolinitic clay particle

    DEFF Research Database (Denmark)

    Gebremariam, Abraham Teklay; Yin, Chungen; Rosendahl, Lasse

    The present work aims at modeling of the calcination (dehydroxylation) process of clay particles, specifically kaolinite, and its thermal transformation. For such purpose, 1D single particle calcination model was developed based on the concept of shrinking core model to assess the dehydroxylation...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-08-31

    example, the excavation-damaged zone (EDZ) near repository tunnels can modify local permeability (resulting from induced fractures), potentially leading to less confinement capability (Tsang et al., 2005). Because of clay's swelling and shrinkage behavior (depending on whether the clay is in imbibition or drainage processes), fracture properties in the EDZ are quite dynamic and evolve over time as hydromechanical conditions change. To understand and model the coupled processes and their impact on repository performance is critical for the defensible performance assessment of a clay repository. Within the Natural Barrier System (NBS) group of the Used Fuel Disposition (UFD) Campaign at DOE's Office of Nuclear Energy, LBNL's research activities have focused on understanding and modeling such coupled processes. LBNL provided a report in this April on literature survey of studies on coupled processes in clay repositories and identification of technical issues and knowledge gaps (Tsang et al., 2010). This report will document other LBNL research activities within the natural system work package, including the development of constitutive relationships for elastic deformation of clay rock (Section 2), a THM modeling study (Section 3) and a THC modeling study (Section 4). The purpose of the THM and THC modeling studies is to demonstrate the current modeling capabilities in dealing with coupled processes in a potential clay repository. In Section 5, we discuss potential future R&D work based on the identified knowledge gaps. The linkage between these activities and related FEPs is presented in Section 6.

  12. Neutrosophic Decision Making Model for Clay-Brick Selection in Construction Field Based on Grey Relational Analysis

    Directory of Open Access Journals (Sweden)

    Kalyan Mondal

    2015-09-01

    Full Text Available The purpose of this paper is to present quality clay-brick selection approach based on multi-attribute decision making with single valued neutrosophic grey relational analysis. Brick plays a significant role in construction field. So it is important to select quality clay-brick for construction based on suitable mathematical decision making tool. There are several selection methods in the literature. Among them decision making with neutrosophic set is very pragmatic and interesting. Neutrosophic set is one tool that can deal with indeterminacy and inconsistent data. In the proposed method, the rating of all alternatives is expressed with single-valued neutrosophic set which is characterized by truth-membership degree (acceptance, indeterminacy membership degree and falsity membership degree (rejection. Weight of each attribute is determined based on experts’ opinions. Neutrosophic grey relational coefficient is used based on Hamming distance between each alternative to ideal neutrosophic estimates reliability solution and ideal neutrosophic estimates unreliability solution. Then neutrosophic relational degree is used to determine the ranking order of all alternatives (bricks. An illustrative numerical example for quality brick selection is solved to show the effectiveness of the proposed method.

  13. Using Modeling Clay to Model the Rock Cycle

    Science.gov (United States)

    Cook, H. M.

    2016-12-01

    During this interactive exploration, students will be guided through the rock cycle using modeling clay as a medium. Each student will be given a ball of red clay and a ball of yellow clay. The instructor will introduce students to igneous rocks as they use their red clay to create a volcano. Students will then learn about weathering and erosion as they break their yellow ball of clay into smaller and smaller pieces that they will round into spheres. The "sand" created from the yellow clay gets accumulated and lithified (via gentle compression by the students) to form a sandstone. This sandstone then becomes covered by a lava flow, created by smashing the red clay volcanoes. The process of metamorphism is introduced as students gently cover their sandstone using the lava flow. This also serves a segue for a discussion about the various types of metamorphism beginning with contact metamorphism. Metamorphic grade is discussed as increased pressure further alters the sedimentary rock and lava flow. Ultimately a migmatite is formed by mixing the red and yellow clay together. Finally, they clays become so intermingled that a new larger orange ball is created, beginning the rock cycle anew with an igneous melt. This activity is engaging and effective with students of all ages. Intended as a fun, light-hearted approach to introducing rocks in an undergraduate earth science class, this can be effectively customized for use in an elementary, middle, or high school classroom.

  14. Modification of clay-based waste containment materials

    Energy Technology Data Exchange (ETDEWEB)

    Adu-Wusu, K. [DuPont Central Research and Development, Newark, DE (United States); Whang, J.M. [DuPont Specialty Chemicals, Deepwater, NJ (United States); McDevitt, M.F. [DuPont Central Research and Development, Wilmington, DE (United States)

    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.

  15. Ductile damage Cam-Clay plasticity and fracture modeling of shale based on nano-characterization experiment

    Science.gov (United States)

    Bennett, K. C.; Borja, R. I.

    2015-12-01

    A finite strain ductile damage formulation of Modified Cam-Clay (MCC) plasticity has been developed in order to model the observed elastoplastic behavior of shale at nano- to micro-scales. Nano-indentation combined with both 2D and 3D imaging was performed on a sample of Woodford shale. Significant plastic deformation was observed in the nano-indentation testing, and nano-scale resolution FIB-SEM imaging of the post-indented regions has revealed that the plastic deformation is accompanied by extensive micro-fracture of the shale's highly heterogeneous micro-structure. A spatial tensor that is similar to Eshelby's energy momentum tensor is shown to be energy conjugate to the plastic velocity gradient under large inelastic volume strain. These results are cast in MCC framework drawing on the concept of continuum damage. The resulting formulation provides a connection between density (porosity), elastic (and plastic) moduli, and micro damage/healing. Nonlinear finite element modeling is used for implementation of the constitutive model in simulation of both laboratory-scale and nano- to micro-scale experiments. The results show that the model is able to predict the inception and propagation of micro-fractures around inhomogeneities, as well as capture the resulting behavior observed at the much larger laboratory scale.

  16. An improved damaging model for structured clays

    Institute of Scientific and Technical Information of China (English)

    姜岩; 雷华阳; 郑刚; 徐舜华

    2008-01-01

    An improved damaging model formulated within the framework of bounding surface for structured clays was proposed. The model was intended to describe the effects of structure degradation due to geotechnical loading. The predictive capability of the model was compared with those of triaxial compression test on Tianjin soft clays. The results show that, by incorporating a new damage function into the model, the reduction of elastic bulk and shear modulus with elastic deformations and the reduction of plastic bulk modulus and shear modulus with plastic deformations are able to be appreciable. Before the axial strain reaches 15%, the axial strain computed from the model is smaller than that from the test under the drained condition. Under the undrained condition, after the axial strain reaches 1%, the axial strain increases quickly because of the complete loss of structure and stiffness; and the result computed from the model is nearly equal to that from the model without the incorporation of the damage function due to less plastic strain under undrained condition test.

  17. Modelling the thermo-mechanical volume change behaviour of compacted expansive clays

    CERN Document Server

    Tang, Anh-Minh; 10.1680/geot.2009.59.3.185

    2009-01-01

    Compacted expansive clays are often considered as a possible buffer material in high-level deep radioactive waste disposals. After the installation of waste canisters, the engineered clay barriers are subjected to thermo-hydro-mechanical actions in the form of water infiltration from the geological barrier, heat dissipation from the radioactive waste canisters, and stresses generated by clay swelling under almost confined conditions. The aim of the present work is to develop a constitutive model that is able to describe the behaviour of compacted expansive clays under these coupled thermo-hydro-mechanical actions. The proposed model is based on two existing models: one for the hydro-mechanical behaviour of compacted expansive clays and another for the thermo-mechanical behaviour of saturated clays. The elaborated model has been validated using the thermo-hydro-mechanical test results on the compacted MX80 bentonite. Comparison between the model prediction and the experimental data show that this model is able...

  18. Nonlinear elastic model for compacted clay concrete interface

    Institute of Scientific and Technical Information of China (English)

    R. R. SHAKIR; Jungao ZHU

    2009-01-01

    In this paper, a nonlinear elastic model was developed to simulate the behavior of compacted clay concrete interface (CCCI) based on the principle of transition mechanism failure (TMF). A number of simple shear tests were conducted on CCCI to demonstrate different failure mechanisms; i.e., sliding failure and deformation failure. The clay soil used in the test was collected from the "Shuang Jang Kou" earth rockfill dam project. It was found that the behavior of the interface depends on the critical water contents by which two failure mechanisms can be recognized. Mathematical relations were proposed between the shear at failure and water content in addition to the transition mechanism indicator.The mathematical relations were then incorporated into the interface model. The performance of the model is verified with the experimental results. The verification shows that the proposed model is capable of predicting the interface shear stress versus the total shear displacement very well.

  19. Stochastic modeling of filtrate alkalinity in water filtration devices: Transport through micro/nano porous clay based ceramic materials

    Science.gov (United States)

    Clay and plant materials such as wood are the raw materials used in manufacture of ceramic water filtration devices around the world. A step by step manufacturing procedure which includes initial mixing, molding and sintering is used. The manufactured ceramic filters have numerous pores which help i...

  20. MODELLING FOR THE STRESS-STRAIN BEHAVIOR OF ANISOTROPICALLY LIGHTLY OVERCONSOLIDATED CLAY

    OpenAIRE

    木幡, 行宏; 三田地, 利之

    1989-01-01

    A series of drained stress probe test on saturated remoulded clay specimens consolidated and rebounded under anisotropic stress condition was performed to investigate the influence of anisotropic stress history and stress path on the stress-strain behavior of clay. Based on the test results, a new constitutive model was proposed which could successfully describe the stress-strain behavior of anisotropically lightly overconsolidated clay.

  1. Toward immersive clay modeling: interactive modeling with octrees

    Science.gov (United States)

    Moritz, Elke; Kuester, Falko; Hamann, Bernd; Joy, Kenneth I.; Hagen, Hans

    2000-05-01

    The described virtual clay modeling project explores the use of virtual environments (VES) for the simulation of two- handed clay modeling and sculpting tasks. Traditional clay modeling concepts are implemented and enhanced with new digital design tools leveraging from virtual reality (VR) and new input device technology. In particular, the creation of an intuitive and natural work environment for comfortable and unconstrained modeling is emphasized. VR projection devices, such as the Immersive WorkBench, shutter glasses, and pinch gloves, equipped with six-degrees-of-freedom trackers, are used to apply various virtual cutting tools to a volumetric data structure . The employment of an octree as underlying data structure for volume representation and manipulation in immersive environments allows real-time modeling of solids utilizing a suite of either geometrically or mathematically defined cutting and modeling tools.

  2. Learning of Cross-Sectional Anatomy Using Clay Models

    Science.gov (United States)

    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…

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

    Science.gov (United States)

    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

  4. Centrifuge modelling of rigid piles in soft clay

    DEFF Research Database (Denmark)

    Klinkvort, R.T.; Poder, M.; Truong, P.

    2016-01-01

    of this study is to employ centrifuge modelling in order to derive experimental p-y curves for rigid piles embedded in over-consolidated soft clay. A kaolin clay sample was prepared and pre-consolidated by applying a constant pressure at the soil surface, while different over-consolidation ratios were achieved...

  5. A two-surface plasticity model for stiff clay

    OpenAIRE

    2015-01-01

    This paper presents a constitutive model for describing some important features of the behavior of natural stiff clay evidenced experimentally such as the limited elastic zone, the presence of strain hardening and softening, and the smooth transition from elastic behavior to a plastic one. The model, namely ACC-2, is an adapted Modified Cam Clay model with two yield surfaces: similarly to bounding surface plasticity theory, an additional yield surface?namely Inner yield surface?was adopted to...

  6. Evaluating sand and clay models: do rheological differences matter?

    Science.gov (United States)

    Eisenstadt, Gloria; Sims, Darrell

    2005-08-01

    Dry sand and wet clay are the most frequently used materials for physical modeling of brittle deformation. We present a series of experiments that shows when the two materials can be used interchangeably, document the differences in deformation patterns and discuss how best to evaluate and apply results of physical models. Extension and shortening produce similar large-scale deformation patterns in dry sand and wet clay models, indicating that the two materials can be used interchangeably for analysis of gross deformation geometries. There are subtle deformation features that are significantly different: (1) fault propagation and fault linkage; (2) fault width, spacing and displacement; (3) extent of deformation zone; and (4) amount of folding vs. faulting. These differences are primarily due to the lower cohesion of sand and its larger grain size. If these features are of interest, the best practice would be to repeat the experiments with more than one material to ensure that rheological differences are not biasing results. Dry sand and wet clay produce very different results in inversion models; almost all faults are reactivated in wet clay, and few, if any, are significantly reactivated in sand models. Fault reactivation is attributed to high fluid pressure along the fault zone in the wet clay, a situation that may be analogous to many rocks. Sand inversion models may be best applied to areas where most faults experience little to no reactivation, while clay models best fit areas where most pre-existing normal faults are reactivated.

  7. Induced polarization of clay-sand mixtures. Experiments and modelling.

    Science.gov (United States)

    Okay, G.; Leroy, P.

    2012-04-01

    The complex conductivity of saturated unconsolidated sand-clay mixtures was experimentally investigated using two types of clay minerals, kaolinite and smectite (mainly Na-Montmorillonite) in the frequency range 1.4 mHz - 12 kHz. The experiments were performed with various clay contents (1, 5, 20, and 100 % in volume of the sand-clay mixture) and salinities (distilled water, 0.1 g/L, 1 g/L, and 10 g/L NaCl solution). Induced polarization measurements were performed with a cylindrical four-electrode sample-holder associated with a SIP-Fuchs II impedance meter and non-polarizing Cu/CuSO4 electrodes. The results illustrate the strong impact of the CEC of the clay minerals upon the complex conductivity. The quadrature conductivity increases steadily with the clay content. We observe that the dependence on frequency of the quadrature conductivity of sand-kaolinite mixtures is more important than for sand-bentonite mixtures. For both types of clay, the quadrature conductivity seems to be fairly independent on the pore fluid salinity except at very low clay contents. The experimental data show good agreement with predicted values given by our SIP model. This complex conductivity model considers the electrochemical polarization of the Stern layer coating the clay particles and the Maxwell-Wagner polarization. We use the differential effective medium theory to calculate the complex conductivity of the porous medium constituted of the grains and the electrolyte. The SIP model includes also the effect of the grain size distribution upon the complex conductivity spectra.

  8. Integrated modelling of the glass-iron-clay system

    Energy Technology Data Exchange (ETDEWEB)

    Bildstein, O

    2007-01-15

    This report summarizes the results of integrated calculations on the near-field evolution in the VHLW/steel/bentonite/clay system. The calculations of the near-field evolution include different components: the vitrified waste packages, the steel container, the bentonite-based EBS (optional), the EDZ and the geological medium. Coupled reaction-transport (X-T) is used to simulate the corrosion of the steel canister and the glass alteration phase in presence of corrosion products (CPs), looking at mass transfer for chemical elements, especially iron and silica, pH, and porosity change. Calculations as performed give actual parameters for PA calculations: rate of glass alteration (through the calculated pH) as a function of time, extension of altered zone for iron-clay interactions with their own transport parameters, nature of CPs, effect on porosity distribution. According to the operational model currently used at the CEA and the calculations performed on the glass-iron-clay system, the alteration rate of glass and the evolution of the system strongly depend on the timing of CPs saturation with respect to silica sorption. The fate of silica which can be sorbed or precipitate is crucial to the lifetime of glass and to the overall evolution of the system. The other process that might influence the glass is the porosity decrease due to the precipitation of CPs and silica rich phases. However, it is difficult to assign a safety functions to clogging. It is scarcely observed in experiments, either because the conditions are not met for clogging or because the timescale of experiments does not allow for observable clogging. Moreover, the effect of mechanical stress in the NF has to be accounted for in the assessment of the effect of porosity changes. (author)

  9. General strategy, clay based disposal concepts and integration (GSI)

    Energy Technology Data Exchange (ETDEWEB)

    Keto, P.; Gunnarsson, G.; Johannesson, L.E.; Hansen, J.; Emmerich, K.; Kemper, G.; Nuesch, R.; Schuhmann, R.; Koniger, F.; Schlager, St.; Gruner, M.; Hofmann, M.; Nuesch, R.; Kobayashi, I.; Toida, M.; Sasakura, T.; Bernier, F.; Li, X.L.; Ileana Denisa, Nistor; Neculai, DoruMiron; Tudor, Sajin; Abdelkrim, Azzouz; Ilie, Siminiceanu; Viswanadham, B.V.S.; Rajesh, S.; Sengupta, S.S.; Panturu, E.; Radulescu, R.; Jinescu, C.; Panturu Razvann, Ioan; Autio, J.; Sanden, T.; Borgesson, L.; Svensson, D.; Eng, A.; Sellin, P.; Dixon, D.A.; Martino, J.B.; Vignal, B.; Fujita, T.; Wei-Hsing, Huang; Wen-Chuan, Chen; Shu-Rong, Yang; Dmitriev, S.; Prozorov, L.; Litinsky, Y.; Tkachenko, A.; Guskov, A.; Sanden, T.; Borgesson, L.; Camp, S.; Gourc, J.P.; Ple, O.; Kaelin, J.L.; Marchiol, A.; Round, C.; Johannesson, L.E.; Nilsson, U.; Adamcova, R.; Frankovska, J.; Durmekova, T.; Haasova, Z.; Gatabin, C.; Guyot, J.L.; Resnikow, S.; Karnland, O.; Nilsson, U.; Weber, H.; Wersin, P.; Gray, M.N.; Dixon, D.A.; Poulesquen, A.; Radwan, J.; Poinssot, C.; Ferry, C.; Weber, H.P.; Plotze, M

    2007-07-01

    This session gathers 20 articles (posters) dealing with: the assessment of backfill materials and methods for deposition tunnels; HTV-1: a semi technical scale testing of a multi-layer hydraulic shaft sealing system; the development of water content adjust method by mixing powdered-ice and chilled bentonite: application to the construction of bentonite engineered barriers by shot-clay method; repository design issues related to the thermal impact induced by heat emitting radioactive waste; pillared clays, using Romanian montmorillonite; the simulation of differential settlements of clay based engineered barrier systems in a geo-centrifuge; the critical issues regarding clay behaviour in the KBS-3H repository design; an alternative buffer material experiment; assessing the performance of a swelling clay tunnel seal and issues identified in the course of its operation; the activation of a Ca-bentonite as buffer material; a large diameter borehole type repository in the clays for radioactive waste long term storage; the erosion of backfill materials during the installation phase; the behaviour of the clay cover of a site for very low level nuclear waste: field flexion tests; the laboratory tests made on three different backfill candidates for the Swedish KBS- 3V concept; the engineering geological clay research for radioactive waste repository in Slovakia; the ESDRED project, module 1 - Design, fabrication, assembly, handling and packaging of buffer rings; the laboratory experiments on the sealing ability of bentonite pellets; the screening of bentonite resources for use as an engineered barrier component in deep geologic repositories; the assessment of the radionuclide release from the near-field environment of a spent nuclear fuel geological repository; and the emplacement tests with granular bentonite.

  10. Luminescent hybrid materials based on laponite clay.

    Science.gov (United States)

    Li, Huanrong; Li, Man; Wang, Yu; Zhang, Wenjun

    2014-08-11

    The spectroscopic behavior of ionic Eu(3+) or Tb(3+) complexes of an aromatic carboxyl-functionalized organic salt as well as those of the hybrid materials derived from adsorption of the ionic complexes on Laponite clay are reported. X-ray diffraction (XRD) patterns suggest that the complexes are mainly adsorbed on the outer surfaces of the Laponite disks rather than intercalated within the interlayer spaces. Photophysical data showed that the energy-transfer efficiency from the ligand to Eu(3+) ions in the hybrid material is increased remarkably with respect to the corresponding ionic complex. The hybrid material containing the Eu(3+) complex shows bright red emission from the prominent (5) D0 →(7) F2 transition of Eu(3+) ions, and that containing the Tb(3+) complex exhibits bright green emission due to the dominant (5) D4 →(7) F5 transition of Tb(3+) ions.

  11. Pesticide leaching in macroporous clay soils: field experiment and modeling

    NARCIS (Netherlands)

    Scorza Júnior, R.P.

    2002-01-01

    Keywords : pesticide leaching, macropores, preferential flow, preferential transport, cracked clay soil, pesticide leaching models, groundwater contamination, inverse modeling, bentazone and imidacloprid. The presence of macropores (i.e. shrinkage c

  12. Modeling and Simulation of Virtual Clay Pigeon shooter Training System

    Directory of Open Access Journals (Sweden)

    Jin Yanxia

    2013-10-01

    Full Text Available As a popular sports event, clay pigeon uses real guns and bullets as its tools. To improve the training effect, reduce its cost and danger, the development of a real-time interactive and perceptive virtual training system by using simulation technology becomes urgent. This system uses Visual C++、Vega、Creator as its development platform to conduct modeling and simulation of clay pigeon’s and grapeshot ‘s flying path and the collision effect of the two objects.  

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

    Science.gov (United States)

    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.

  14. Cyclostratigraphy for Chinese red clay sequences: Implications to changing previous age models and paleoclimate interpretations

    Science.gov (United States)

    Anwar, T.; Kravchinsky, V. A.; Zhang, R.

    2015-12-01

    The Chinese Loess Plateau contains red clay sequence which has continuous alternation of sedimentary cycles with recurrent paleoclimatic fluctuations. Absence of abundant fossils and inability of radiometric dating method made magnetostratigraphy a leading method to build age model for the red clay. Here magnetostratigraphic age model in red clay sequence is tested using cyclostratigraphy as orbital parameters of Earth are known. Milankovitch periodicities recorded in magnetic susceptibility and grain size in the Shilou red clay section are investigated and previously found age of 11 Ma for this section is re-evaluated. Magnetostratigraphy dating based on only visual correlation could potentially lead to erroneous age model. In this study the correlation is executed through the iteration procedure until it is supported by cyclostratigraphy; i.e. Milankovitch cycles are resolved in the best possible manner. Our new approach provides an age of 5.2 Ma for the Shilou profile. Wavelet analysis reveals that a 400 kyr eccentricity cycle is well preserved and the existence of a 100 kyr eccentricity in the red clay sequence on the eastern Chinese Loess Plateau suggests that eccentricity plays a vital role in Pliocene climate evolution. Paleomonsoon evolution is reconstructed and divided into three intervals (5.2-4.5 Ma, 4.5-3.6 Ma and 3.6-2.58 Ma). The earliest stage indicates that summer and winter monsoon cycles may rapidly alter, whereas the middle stage reflects an intensification of winter monsoon and aridification in Asia, and the youngest stage is characterized by relatively intensified summer monsoon. This study demonstrates that cyclostratigraphy can greatly assist magnetostratigraphy in dating the red clay sequences, and implies that many published age models for the red clay sequences should likely be re-assessed where possible. An evaluation of the monsoon system and climate change in eastern Asia might prominently benefit from this approach.

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

    Directory of Open Access Journals (Sweden)

    Deka Harekrishna

    2009-01-01

    Full Text Available Abstract 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.

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

    Science.gov (United States)

    Deka, Harekrishna; Karak, Niranjan

    2009-07-01

    The highly branched polyurethanes and vegetable oil-based polymer nanocomposites have been showing fruitful advantages across a spectrum of potential field of applications. Mesua ferrea L. 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.

  17. Magnetic fabric analyses in analogue models of clays

    Science.gov (United States)

    García-Lasanta, Cristina; Román-Berdiel, Teresa; Izquierdo-Llavall, Esther; Casas-Sainz, Antonio

    2017-04-01

    Anisotropy of magnetic susceptibility (AMS) studies in sedimentary rocks subjected to deformation indicate that magnetic fabrics orientation can be conditioned by multiple factors: sedimentary conditions, magnetic mineralogy, successive tectonic events, etc. All of them difficult the interpretation of the AMS as a marker of the deformation conditions. Analogue modeling allows to isolate the variables that act in a geological process and to determine the factors and in which extent they influence in the process. This study shows the magnetic fabric analyses applied to several analogue models developed with common commercial red clays. This material resembles natural clay materials that, despite their greater degree of impurities and heterogeneity, have been proved to record a robust magnetic signal carried by a mixture of para- and ferromagnetic minerals. The magnetic behavior of the modeled clay has been characterized by temperature dependent magnetic susceptibility curves (from 40 to 700°C). The measurements were performed combining a KLY-3S Kappabridge susceptometer with a CS3 furnace (AGICO Inc., Czech Republic). The obtained results indicate the presence of an important content of hematite as ferromagnetic phase, as well as a remarkable paramagnetic fraction, probably constituted by phyllosilicates. This mineralogy is common in natural materials such as Permo-Triassic red facies, and magnetic fabric analyses in these natural examples have given consistent results in different tectonic contexts. In this study, sedimentary conditions and magnetic mineralogy are kept constant and the influence of the tectonic regime in the magnetic fabrics is analyzed. Our main objective is to reproduce several tectonic contexts (strike-slip and compression) in a sedimentary environment where material is not yet compacted, in order to determine how tectonic conditions influence the magnetic fabric registered in each case. By dispersing the clays in water and after allowing their

  18. Geopolymers Based on Phosphoric Acid and Illito-Kaolinitic Clay

    Directory of Open Access Journals (Sweden)

    S. Louati

    2016-01-01

    Full Text Available New three-dimensional geopolymer materials based on illito-kaolinitic clay and phosphoric acid were synthesized. The effect of Si/P molar ratio on the geopolymers properties was studied. Raw, calcined clay, and geopolymers structures were investigated using XRD, IR spectroscopy, and SEM. The phosphoric acid-based geopolymers mechanical properties were evaluated by measuring the compressive strength. The Si/P molar ratio was found to increase with the increase of the compressive strength of the obtained geopolymers, which attained a maximum value at Si/P equal to 2.75. Beyond this ratio, the mechanical strength decreases. The XRD patterns of these geopolymers samples have proven that when the Si/P molar ratio decreases, the amorphous phase content increases. Besides, the structural analyses have revealed the presence of aluminum phosphate and Si-O-Al-O-P polymeric structure, whatever the Si/P molar ratio is (between 2.25 and 3.5. The obtained results have confirmed that the presence of the associated minerals such as hematite and quartz in the clay does not prevent the geopolymerization reaction, but the presence of illite mineral seems to have a modest contribution in the geopolymerization.

  19. FINITE ELEMENT ANALYSIS OF PILE BASED ON MODIFIED CAM-CLAY MODEL%基于修正剑桥模型桩的有限元分析

    Institute of Scientific and Technical Information of China (English)

    李婷; 杨鼎久

    2012-01-01

    Pile is considered as a series of constant along the length of the spherical cavity expansion point forming process. The stress distribution due to the spheric cavity expansion is diveded into three zones: flow damage, plastic deformation zone and elastic deformation zone. The analytical expression for distribution of the stress and displacement could be deduced on the basis of the cavity expansion theory combining with the Modified Cam-clay model. Then compared with the result of the finite element ABAQUS .%将桩挤土过程视作沿桩长不变的一系列点位形成的球形扩张过程,把扩张过程中的桩周土体分成3个区域:流动区域、塑性变形区和弹性变形区。应用圆孔扩张理论,结合修正剑桥模型推导出了球形孔扩张引起的土体应力、位移分布解析解,并与有限元ABAQUS模拟的结果对比分析。

  20. Reactive Transport Modeling and Changes in Porosity at Reactive Interfaces in a HLW repository in Clay

    Science.gov (United States)

    Samper, J.; Mon, A.; Montenegro, L.; Naves, A.; Fernández, J.

    2016-12-01

    High-level radioactive waste disposal in a deep geological repository is based on a multibarrier concept which combines natural barriers such as the geological formation and artificial barriers such as metallic containers, bentonite and concrete buffers and sealing materials. The stability and performance of the bentonite barrier could be affected by the corrosion products at the canister-bentonite interface and the hyperalkaline conditions caused by the degradation of concrete at the bentonite-concrete interface. Additionally, the host clay formation could also be affected by the hyperalkaline plume at the concrete-clay interface. Here we present a nonisothermal reactive transport model of the long-term interactions of the compacted bentonite with the corrosion products of a carbon-steel canister and the concrete liner of the engineered barrier of a high-level radioactive waste repository in clay. This problem involves large pH changes with a hyperalkaline high-pH plume, complex mineral dissolution/precipitation patterns, cation exchange reactions and proton surface complexation. These reactions lead to large changes in porosity which can even lead to pore clogging. Model results show that magnetite, the main corrosion product, precipitates and reduces significantly the porosity of the bentonite near the canister. The degradation of the concrete liner leads to the precipitation of secondary minerals and the reduction of the porosity of the bentonite and the clay formation at their interfaces with the concrete liner. The zones affected by pore clogging at the canister-bentonite, bentonite-concrete and concrete-clay interfaces at 1 Ma are equal to 10, 25 and 25 mm thick, respectively. The results of our simulations share many of the features of the models reported by others for engineered barrier systems at similar chemical conditions, including: 1) Narrow alteration zones; and 2) Pore clogging at the canister-bentonite, bentonite-concrete and concrete-clay

  1. Method of Numerical Modeling for Constitutive Relations of Clay

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In order to study the method of numerical modeling for constitutive relations of clay, on the basis of the principle of interaction between plastic volumetric strain and plastic generalized shear strain, the two constitutive functionals that include the function of stress path were used as the basic framework of the constitutive model, which are able to demonstrate the dependence of stress path.The two partial differential cross terms appear in the expression of stress-strain increment relation, which are used to demonstrate the interaction between plastic volumetric strain and plastic generalized shear strain.The elasoplastic constitutive models of clay under two kinds of stress paths, CTC and TC, have been constructed using the triaxial test results.The three basic characteristics of deformation of soils, pressure sensitivity, dilatancy, and dependence of stress path, are well explained using these two models.Using visualization, the three-dimensional surfaces of shear and volume strains in the whole stress field under stress paths of CTC and TC are given.In addition, the two families of shear and volumetric yield loci under CTC and TC paths are plotted respectively.By comparing the results of deformation under these two stress paths, it has been found that, there are obvious differences in the strain peaks, the shapes of strain surfaces, and the trends of variation of volumetric yield loci, however both families of shear yield loci are similar.These results demonstrate that the influences of stress path on the constitutive relations of clay are considerably large and not negligible.The numerical modeling method that can sufficiently reflect the dependence of stress path is superior to the traditional one.

  2. Intensified Pozzolanic Reaction on Kaolinite Clay-Based Mortar

    Directory of Open Access Journals (Sweden)

    Yang-Hee Kwon

    2017-05-01

    Full Text Available The objective of this study is to develop and characterize kaolinite clay-based structural mortar. The pozzolanic reaction induced from two mineral additives, i.e., calcium hydroxide and silica fume (SF, and the physical filling effect from SF, were found to be effective on the enhancement of structural properties. Based on several preliminary experiments, 7:3 ratio of kaolinite clay/calcium hydroxide was selected as a basic binder. Then, the amount of SF was chosen as 0%, 7.5%, and 15% of the total binder to consider both the chemical and physical effects. The results showed that compressive strengths of samples with 7.5% and 15% SF are significantly increased by approximately 200% and 350%, respectively, at 28 days compared to the sample without SF. However, based on the results of the sample with 15% SF, it is found that excessive addition of SF causes long-term strength loss, possibly owing to micro cracks. With the careful consideration on this long-term behavior, this suggested new mix design can be further extended to develop sustainable structural materials using natural minerals or waste materials with nonbinding properties.

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

    Science.gov (United States)

    Droge, Steven T J; Goss, Kai-Uwe

    2013-12-17

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

  4. Critical review of coupled flux formulations for clay membranes based on nonequilibrium thermodynamics.

    Science.gov (United States)

    Malusis, Michael A; Shackelford, Charles D; Maneval, James E

    2012-09-01

    . The results indicate that, despite the theoretical inconsistency between the counter-diffusion assumption and the salt-diffusion conditions of the experiments, the predictive ability of solute transport theory based on the assumption of counter diffusion is not significantly different from that based on the assumption of salt diffusion, provided that the input parameters used in each theory are derived under the same assumption inherent in the theory. Nonetheless, salt-diffusion theory is fundamentally correct and, therefore, is more appropriate for problems involving salt diffusion in clay membranes. Finally, the fact that solute diffusion cannot occur in an ideal or perfect membrane is not explicitly captured in any of the theoretical expressions for total solute flux in clay membranes, but rather is generally accounted for via inclusion of an effective porosity, n(e), or a restrictive tortuosity factor, τ(r), in the formulation of Fick's first law for diffusion. Both n(e) and τ(r) have been correlated as a linear function of membrane efficiency. This linear correlation is supported theoretically by pore-scale modeling of solid-liquid interactions, but experimental support is limited. Additional data are needed to bolster the validity of the linear correlation for clay membranes.

  5. Formulation of cracking catalyst based on zeolite and natural clays

    Energy Technology Data Exchange (ETDEWEB)

    Aliev, R.R.; Lupina, M.I.

    1995-11-01

    Domestically manufactured cracking catalysts are based on a synthetic amorphous aluminosilicate matrix and Y zeolite. A multistage {open_quotes}gel{close_quotes} technology is used in manufacturing the catalysts. The process includes mixing solutions of sodium silicate and acidic aluminum sulfate, forming, syneresis, and activation of the beaded gel. In the manufacture of bead catalysts, the next steps in the process are washing, drying, and calcining; in the manufacture of microbead catalysts, the next steps are dispersion and formation of a hydrogel slurry, spray-drying, and calcining. The Y zeolite is either introduced into the alumina-silica sol in the stage of forming the beads, or introduced in the dispersion stage. With the aim of developing an active and selective cracking catalyst based on Y zeolite and natural clays, with improved physicomechanical properties, the authors carried out a series of studies, obtaining results that are set forth in the present article.

  6. Slope stability assessment of weathered clay by using field data and computer modelling: a case study from Budapest

    Directory of Open Access Journals (Sweden)

    P. Görög

    2007-06-01

    Full Text Available A future development site of a housing estate, an abandoned-brick yard with clayey slopes was studied in details to assess slope stability and to calculate the factor of safety. The Oligocene clay, the former raw material, is divided into two different geotechnical units in the clay pit. The lower one consists of grey impermeable clays while the upper unit is characterised by yellowish weathered clay having a limited permeability. At some localities the topmost weathered clay layers are covered by loess, and slope debris. Parts of the former pit were also used as a landfill site. The slope stability analyses were performed based on borehole information and laboratory analyses in order to provide necessary engineering geological data for further site development and urban planning. Two geotechnical codes Plaxis and Geo4 were used to model the slope failures and assess the slope stability. The aim of using two different approaches was to compare them since Plaxis uses finite elements modelling while Geo4 uses conventional calculation methods to obtain circular and polygonal slip surfaces. According to model calculations and field data, the main trigger mechanisms of landslides seem to be high pore pressure due to rainwater and small slope debris covered springs. The slip surface is located at the boundary zone of yellow weathered and grey unaltered clay. Two computer models gave very similar results; although Plaxis provides combined safety factor which is slightly more pessimistic when compared to the safety factor obtained by using Geo4.

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

    Science.gov (United States)

    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.

  8. Clay Generic Disposal System Model - Sensitivity Analysis for 32 PWR Assembly Canisters (+2 associated model files).

    Energy Technology Data Exchange (ETDEWEB)

    Morris, Edgar [Argonne National Lab. (ANL), Argonne, IL (United States)

    2014-10-01

    The Used Fuel Disposition Campaign (UFDC), as part of the DOE Office of Nuclear Energy’s (DOE-NE) Fuel Cycle Technology program (FCT) is investigating the disposal of high level radioactive waste (HLW) and spent nuclear fuela (SNF) in a variety of geologic media. The feasibility of disposing SNF and HLW in clay media has been investigated and has been shown to be promising [Ref. 1]. In addition the disposal of these wastes in clay media is being investigated in Belgium, France, and Switzerland. Thus, Argillaceous media is one of the environments being considered by UFDC. As identified by researchers at Sandia National Laboratory, potentially suitable formations that may exist in the U.S. include mudstone, clay, shale, and argillite formations [Ref. 1]. These formations encompass a broad range of material properties. In this report, reference to clay media is intended to cover the full range of material properties. This report presents the status of the development of a simulation model for evaluating the performance of generic clay media. The clay Generic Disposal System Model (GDSM) repository performance simulation tool has been developed with the flexibility to evaluate not only different properties, but different waste streams/forms and different repository designs and engineered barrier configurations/ materials that could be used to dispose of these wastes.

  9. Anatomical Knowledge Gain through a Clay-Modeling Exercise Compared to Live and Video Observations

    Science.gov (United States)

    Kooloos, Jan G. M.; Schepens-Franke, Annelieke N.; Bergman, Esther M.; Donders, Rogier A. R. T.; Vorstenbosch, Marc A. T. M.

    2014-01-01

    Clay modeling is increasingly used as a teaching method other than dissection. The haptic experience during clay modeling is supposed to correspond to the learning effect of manipulations during exercises in the dissection room involving tissues and organs. We questioned this assumption in two pretest-post-test experiments. In these experiments,…

  10. Clay Modeling as a Method to Learn Human Muscles: A Community College Study

    Science.gov (United States)

    Motoike, Howard K.; O'Kane, Robyn L.; Lenchner, Erez; Haspel, Carol

    2009-01-01

    The efficacy of clay modeling compared with cat dissection for human muscle identification was examined over two semesters at LaGuardia Community College in Queens, NY. The 181 students in 10 sections in this study were randomly distributed into control (cat dissection) and experimental (clay modeling) groups, and the results of the muscle…

  11. Anatomical knowledge gain through a clay-modeling exercise compared to live and video observations

    NARCIS (Netherlands)

    Kooloos, J.G.M.; Schepens-Franke, A.N.; Bergman, E.M.; Donders, R.; Vorstenbosch, M.A.

    2014-01-01

    Clay modeling is increasingly used as a teaching method other than dissection. The haptic experience during clay modeling is supposed to correspond to the learning effect of manipulations during exercises in the dissection room involving tissues and organs. We questioned this assumption in two prete

  12. Experimental validation of Swy-2 clay standard's PHREEQC model

    Science.gov (United States)

    Szabó, Zsuzsanna; Hegyfalvi, Csaba; Freiler, Ágnes; Udvardi, Beatrix; Kónya, Péter; Székely, Edit; Falus, György

    2017-04-01

    One of the challenges of the present century is to limit the greenhouse gas emissions for the mitigation of climate change which is possible for example by a transitional technology, CCS (Carbon Capture and Storage) and, among others, by the increase of nuclear proportion in the energy mix. Clay minerals are considered to be responsible for the low permeability and sealing capacity of caprocks sealing off stored CO2 and they are also the main constituents of bentonite in high level radioactive waste disposal facilities. The understanding of clay behaviour in these deep geological environments is possible through laboratory batch experiments of well-known standards and coupled geochemical models. Such experimentally validated models are scarce even though they allow deriving more precise long-term predictions of mineral reactions and rock and bentonite degradation underground and, therefore, ensuring the safety of the above technologies and increase their public acceptance. This ongoing work aims to create a kinetic geochemical model of Na-montmorillonite standard Swy-2 in the widely used PHREEQC code, supported by solution and mineral composition results from batch experiments. Several four days experiments have been carried out in 1:35 rock:water ratio at atmospheric conditions, and with inert and CO2 supercritical phase at 100 bar and 80 ⁰C relevant for the potential Hungarian CO2 reservoir complex. Solution samples have been taken during and after experiments and their compositions were measured by ICP-OES. The treated solid phase has been analysed by XRD and ATR-FTIR and compared to in-parallel measured references (dried Swy-2). Kinetic geochemical modelling of the experimental conditions has been performed by PHREEQC version 3 using equations and kinetic rate parameters from the USGS report of Palandri and Kharaka (2004). The visualization of experimental and numerous modelling results has been automatized by R. Experiments and models show very fast

  13. Calculation of Clay Permeability Using a Rectangular Particle-Water Film Model by the Double-Scale Asymptotic Expansion Method

    Directory of Open Access Journals (Sweden)

    Xiaowu Tang

    2016-01-01

    Full Text Available Permeability of soil plays an important role in geotechnical engineering and is commonly determined by methods combining measurements with theory. Using the double-scale asymptotic expansion method, the Navier-Stokes equation is numerically solved to calculate the permeability, based on the homogenization method and the assumption that the homogeneous microstructure of the relevant porous media is represented accurately as the Representative Elemental Volume (REV. In this study, the commonly used square model is tested in the calculation of sea clay permeability. The results show large deviations. It is suspected that the square model could not represent the flattened shape of the clay particles and the bound water film wrapping around them. Hence, the Rectangle Particle-Water Film Model (i.e., the R-W model is proposed. After determining the horizontal and vertical characteristic length of the unit cell using two pairs of initial data, the permeabilities of other different void ratios could be inversely calculated. The results of three types of clay obtained using the R-W model agree well with the experimental data. This shows the efficient feasibility and accuracy of the R-W model by providing a good representation of the clay particles when using the double-scale asymptotic expansion method to calculate clay permeability.

  14. A remediation performance model for enhanced metabolic reductive dechlorination of chloroethenes in fractured clay till

    DEFF Research Database (Denmark)

    Manoli, Gabriele; Chambon, Julie C.; Bjerg, Poul L.;

    2012-01-01

    ). The model is tested on lab batch experiments and applied to describe sediment core samples from a TCE-contaminated site. Model simulations compare favorably to field observations and demonstrate that dechlorination may be limited to narrow bioactive zones in the clay matrix around fractures and sand......A numerical model of metabolic reductive dechlorination is used to describe the performance of enhanced bioremediation in fractured clay till. The model is developed to simulate field observations of a full scale bioremediation scheme in a fractured clay till and thereby to assess remediation...... efficiency and timeframe. A relatively simple approach is used to link the fermentation of the electron donor soybean oil to the sequential dechlorination of trichloroethene (TCE) while considering redox conditions and the heterogeneous clay till system (clay till matrix, fractures and sand stringers...

  15. Characteristics of model polyelectrolyte multilayer films containing laponite clay nanoparticles.

    Science.gov (United States)

    Elzbieciak, M; Wodka, D; Zapotoczny, S; Nowak, P; Warszynski, P

    2010-01-05

    Polyelectrolyte films structure formed by the "layer-by-layer" (LbL) technique can be enriched by addition of charged nanoparticles like carbon nanotubes and silver or hydroxyapatite nanoparticles, which can improve properties of the polyelectrolyte films or modify their functionality. In our paper we examined the formation and properties of model polyelectrolyte multilayers containing a synthetic layered silicate, Laponite. The Laponite nanoparticles were incorporated into multilayer films, which were formed from weak, branched polycation PEI and strong polyanion PSS. Since charge of PEI is pH-dependent, we build up multilayer films in two deposition conditions: pH = 6 when PEI was strongly charged and pH = 10.5 when charge density of PEI was low. Thicknesses of the films constructed with various numbers of Laponite layers were measured by single wavelength ellipsometry. We also determined the differences in permeability for selected electroactive molecules using cyclic voltamperometry. Properties of the films containing clay nanoparticles were compared with model polyelectrolyte multilayer films PEI/PSS formed at the same conditions. We found that Laponite nanoparticles strongly influenced PEI/PSS multilayer film properties. Replacement of PSS by Laponite eliminated the oscillations of the film thickness in the case when PEI was weakly charged. PSS layer adsorbed on top of PEI/Laponite bilayers increased the thickness of multilayer films and improved their barrier properties so synergistic effects between these properties for polyelectrolytes and Laponite nanoparticles could be observed.

  16. Factors affecting the hydraulic performance of infiltration based SUDS in clay

    DEFF Research Database (Denmark)

    Bockhorn, B.; Klint, K.E.S.; Locatelli, Luca;

    2015-01-01

    The influence of small scale soil heterogeneity on the hydraulic performance of infiltration based SUDS was studied using field data from a clayey glacial till and groundwater simulations with the integrated surface water and groundwater model HydroGeoSphere. Simulations of homogeneous soil blocks...... that exclusion of small scale soil physical features may greatly underestimate hydraulic performance of infiltration based SUDS....... with hydraulic properties ranging from sand to clay showed that infiltration capacities vary greatly for the different soil types observed in glacial till. The inclusion of heterogeneities dramatically increased infiltration volume by a factor of 22 for a soil with structural changes above and below the CaC03...

  17. Using digital elevation models as an environmental predictor for soil clay contents

    DEFF Research Database (Denmark)

    Greve, Mogens Humlekrog; Bou Kheir, Rania; Greve, Mette Balslev

    2012-01-01

    The objective of this study was to evaluate the Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM) as an environmental predictor for soil clay content (SCC). It was based on the applicability of different DEMs, i.e., SRTM with 90-m resolution and airborne Light Detection...... and Ranging (LIDAR) (in 24- and 90-m resolution), using regression-tree analysis. Ten terrain parameters were generated from these DEMs. These terrain parameters were used along other environmental variables to statistically explain SCC content in Denmark. Results indicated that the SRTM tree model (T1: 90-m...

  18. Interaction of ordinary Portland cement and Opalinus Clay: Dual porosity modelling compared to experimental data

    Science.gov (United States)

    Jenni, A.; Gimmi, T.; Alt-Epping, P.; Mäder, U.; Cloet, V.

    2017-06-01

    Interactions between concrete and clays are driven by the strong chemical gradients in pore water and involve mineral reactions in both materials. In the context of a radioactive waste repository, these reactions may influence safety-relevant clay properties such as swelling pressure, permeability or radionuclide retention. Interfaces between ordinary Portland cement and Opalinus Clay show weaker, but more extensive chemical disturbance compared to a contact between low-pH cement and Opalinus Clay. As a consequence of chemical reactions porosity changes occur at cement-clay interfaces. These changes are stronger and may lead to complete pore clogging in the case of low-pH cements. The prediction of pore clogging by reactive transport simulations is very sensitive to the magnitude of diffusive solute fluxes, cement clinker chemistry, and phase reaction kinetics. For instance, the consideration of anion-depleted porosity in clays substantially influences overall diffusion and pore clogging at interfaces. A new concept of dual porosity modelling approximating Donnan equilibrium is developed and applied to an ordinary Portland cement - Opalinus Clay interface. The model predictions are compared with data from the cement-clay interaction (CI) field experiment in the Mt Terri underground rock laboratory (Switzerland), which represent 5 y of interaction. The main observations such as the decalcification of the cement at the interface, the Mg enrichment in the clay detached from the interface, and the S enrichment in the cement detached from the interface, are qualitatively predicted by the new model approach. The model results reveal multiple coupled processes that create the observed features. The quantitative agreement of modelled and measured data can be improved if uncertainties of key input parameters (tortuosities, reaction kinetics, especially of clay minerals) can be reduced.

  19. Factors affecting the design of slow release formulations of herbicides based on clay-surfactant systems. A methodological approach.

    Directory of Open Access Journals (Sweden)

    María Del Carmen Galán-Jiménez

    Full Text Available A search for clay-surfactant based formulations with high percentage of the active ingredient, which can yield slow release of active molecules is described. The active ingredients were the herbicides metribuzin (MZ, mesotrione (MS and flurtamone (FL, whose solubilities were examined in the presence of four commercial surfactants; (i neutral: two berols (B048, B266 and an alkylpolyglucoside (AG6202; (ii cationic: an ethoxylated amine (ET/15. Significant percent of active ingredient (a.i. in the clay/surfactant/herbicide formulations could be achieved only when most of the surfactant was added as micelles. MZ and FL were well solubilized by berols, whereas MS by ET/15. Sorption of surfactants on the clay mineral sepiolite occurred mostly by sorption of micelles, and the loadings exceeded the CEC. Higher loadings were determined for B266 and ET/15. The sorption of surfactants was modeled by using the Langmuir-Scatchard equation which permitted the determination of binding coefficients that could be used for further predictions of the sorbed amounts of surfactants under a wide range of clay/surfactant ratios. A possibility was tested of designing clay-surfactant based formulations of certain herbicides by assuming the same ratio between herbicides and surfactants in the formulations as for herbicides incorporated in micelles in solution. Calculations indicated that satisfactory FL formulations could not be synthesized. The experimental fractions of herbicides in the formulations were in agreement with the predicted ones for MS and MZ. The validity of this approach was confirmed in in vitro release tests that showed a slowing down of the release of a.i. from the designed formulations relative to the technical products. Soil dissipation studies with MS formulations also showed improved bioactivity of the clay-surfactant formulation relative to the commercial one. This methodological approach can be extended to other clay-surfactant systems for

  20. Chemically specific multiscale modeling of clay-polymer nanocomposites reveals intercalation dynamics, tactoid self-assembly and emergent materials properties.

    Science.gov (United States)

    Suter, James L; Groen, Derek; Coveney, Peter V

    2015-02-01

    A quantitative description is presented of the dynamical process of polymer intercalation into clay tactoids and the ensuing aggregation of polymer-entangled tactoids into larger structures, obtaining various characteristics of these nanocomposites, including clay-layer spacings, out-of-plane clay-sheet bending energies, X-ray diffractograms, and materials properties. This model of clay-polymer interactions is based on a three-level approach, which uses quantum mechanical and atomistic descriptions to derive a coarse-grained yet chemically specific representation that can resolve processes on hitherto inaccessible length and time scales. The approach is applied to study collections of clay mineral tactoids interacting with two synthetic polymers, poly(ethylene glycol) and poly(vinyl alcohol). The controlled behavior of layered materials in a polymer matrix is centrally important for many engineering and manufacturing applications. This approach opens up a route to computing the properties of complex soft materials based on knowledge of their chemical composition, molecular structure, and processing conditions. © 2014 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Effect of Heat Treatment Temperature on Properties of Chinese Calcined Flint Clay Based Plastic Refractories

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wei; DAI Wenyong; YU Xinfeng; LI Liang

    2009-01-01

    Effects of different heat treatment temperatures on properties of Chinese calcined flint clay based plastic refractories were investigated using Chinese calcined flint clay as starting material,aluminum sulfate and fireclay as binding system.The results showed that with temperature rising,Chinese calcined flint clay based plastic refractories shrinked firstly and then expanded.The modulus of rupture (MOR) and the cold crushing strength (CCS) increased firstly and then decreased from 110 ℃ to 600 ℃,then increased obviously.Thermal expansion coefficient increased from 110 ℃ to 760 ℃,decreased from 760 ℃ to 1 300 ℃,and increased from 1 300 ℃ to 1 500 ℃.

  2. The Delft Sand, Clay and Rock Cutting Model

    NARCIS (Netherlands)

    Miedema, S.A.

    2014-01-01

    Sand, clay and rock have to be excavated for a variety of purposes, such as dredging, trenching, mining (including deep sea mining), drilling, tunnel boring and many other applications. Many excavations take place on dry land, but they are also frequently required in completely saturated conditions,

  3. Modelling iron clay interactions in deep geological disposal conditions

    Science.gov (United States)

    Bildstein, O.; Trotignon, L.; Perronnet, M.; Jullien, M.

    In the context of deep geological disposal of high level radioactive wastes, the interactions between iron and clay-rich materials may lead to adverse transformations of clay minerals with a potential loss of confining properties such as swelling and capacity to exchange cations. Such transformations have been experimentally observed at temperatures starting at ca. 80 °C, where smectites contained in a mixture of bentonite and iron powder are transformed into iron-rich serpentine-type minerals. The reaction-transport code CRUNCH is used to investigate the iron-clay interactions at 50 °C over a period of 10,000 years, which are the conditions considered here to represent the mean temperature value and the expected timescale for the corrosion stage. The aim is to predict the nature and quantity of corrosion product, calculate the chemistry of water (essentially the pH) and the mineralogical transformation in the system containing the canister, an optional engineered barrier (bentonite) and the host-rock (argillite). The results of the calculations show that at the interface with the canister, where steel corrosion occurs, the iron is partly immobilized by the precipitation of iron oxides (essentially magnetite) and small amounts of siderite. The pH stabilizes at high values, between 10 and 11, at this location. In the bentonite or the argillite in contact with the container, the primary clay minerals are destabilized and iron-rich serpentine-like minerals precipitate as observed in the experiments (cronstedtite and berthierine). These minerals show low cation exchange and swelling capacities. The results also show that the interactions between iron and clay may lead to significant porosity changes in the system. A reduction of the porosity is predicted at the surface of the steel canister, due to the precipitation of iron oxides. Porosity increase is predicted in the clay material due to the dissolution of the primary clay minerals. The effect of these porosity

  4. Spectroscopic characterization of schiff base-copper complexes immobilized in smectite clays

    Directory of Open Access Journals (Sweden)

    Patrícia M. Dias

    2010-01-01

    Full Text Available Herein, the immobilization of some Schiff base-copper(II complexes in smectite clays is described as a strategy for the heterogenization of homogeneous catalysts. The obtained materials were characterized by spectroscopic techniques, mostly UV/Vis, EPR, XANES and luminescence spectroscopy. SWy-2 and synthetic Laponite clays were used for the immobilization of two different complexes that have previously shown catalytic activity in the dismutation of superoxide radicals, and disproportionation of hydrogen peroxide. The obtained results indicated the occurrence of an intriguing intramolecular redox process involving copper and the imine ligand at the surface of the clays. These studies are supported by computational calculations.

  5. Synthesis of chitin-bentonite clay based polyurethane bio-nanocomposites.

    Science.gov (United States)

    Zuber, Mohammad; Zia, Khalid Mahmood; Mahboob, Shahid; Hassan, Muhammad; Bhatti, Ijaz Ahmad

    2010-08-01

    Chitin based polyurethane bio-nanocomposites (PUBNC) were prepared by emulsion polymerization. A mixture of polymer and bentonite clay enriched in montmorillonite (MMT) was formed in emulsion polymerization, in which MMT dispersed differently depending on interaction of MMT with polymer chains. Cation exchange capacity (CEC) of bentonite clay enriched in montmorillonite was found 74meq/100g. The existence of the intercalated clay by PU in the hybrid was confirmed using optical microscope (OM) technique. Optical microscope (OM) photographs verified the well dispersed ordered intercalated assembles layers of bentonite in PU matrix. Copyright 2010 Elsevier B.V. All rights reserved.

  6. Investigation of the overconsolidation and structural behavior of Shanghai clays by element testing and constitutive modeling

    Directory of Open Access Journals (Sweden)

    Guan-lin Ye

    2016-09-01

    Full Text Available The mechanical properties and constitutive modeling of Shanghai clays are very important for numerical analysis on geotechnical engineering in Shanghai, where continuous layers of soft clays run 30–40 m deep. The clays are divided into 5 major layers. A series of laboratory tests are carried out to investigate their mechanical properties. The top and bottom layers are overconsolidated hard clays, and the middle layers are normally consolidated or lightly overconsolidated sensitive marine clays. A constitutive model, which can describe the overconsolidation and structure of soils using only 8 parameters, is modified to simulate the test results. A rational procedure to determine the values of the material parameters and initial conditions is also proposed. The model is able to effectively reproduce both one-dimensional (1D consolidation and drained/undrained triaxial test results of Shanghai clays, with one set of parameters for each layer. From element testing and constitutive modeling, two findings are obtained. First, the decay rates of overconsolidation are smaller in overconsolidated layers than in normally consolidated layers. Second, the natural microstructure of layer 4 is relatively stable, that is, a large degree of structure is still maintained in the specimen even after 1D consolidation and drained triaxial tests. The modified model and obtained parameter values can be used for numerical analysis of geotechnical projects in Shanghai.

  7. Derivation of in situ opalinus clay porewater compositions from experimental and geochemical modelling studies

    Energy Technology Data Exchange (ETDEWEB)

    Bradbury, M.H.; Baeyens, B. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-12-01

    Many countries are considering argillaceous sedimentary rocks as potential formations for the disposal of high level radioactive waste. One of the main attractions of such formations from a waste management viewpoint are their generally low groundwater flow rates. However, porewater chemistry constitutes an important basic data set for performance assessment studies and the low transmissivities often mean that it is very difficult, or even impossible, to obtain good in situ water samples. This report describes procedures based on physico-chemical characterisation of whole rock samples and geochemical modelling which were developed as an additional tool for determining porewater compositions in low porosity/permeability clay rich systems. The methodology was applied to core samples of opalinus clay within the framework of an international investigation being carried out at Mt. Terri, Canton Jura, Switzerland. The calculated porewater compositions are described and discussed in relation to experimental data from the analyses of borehole seepage water and water samples obtained from squeezing tests. Because the latter two waters were clearly out of the equilibrium, only a comparison based on general aqueous features was attempted. In all three cases the groundwaters were high ionic strength Na-Cl types. The experimentally determined pH values were in the range 7.5-8 whereas for the modelled porewater a value near 6 was calculated. This discrepancy was explained by postulating that the sampled waters lost dissolved CO{sub 2} through out-gassing. (author) 5 figs., 11 tabs., refs.

  8. Water retention of rigid soils from a two-factor model for clay

    CERN Document Server

    Chertkov, V Y

    2014-01-01

    Water retention is one of the key soil characteristics. Available models of soil water retention relate to the curve-fitting type. The objective of this work is to suggest a physical model of water retention (drying branch) for soils with a rigid matrix. "Physical" means the prediction based on the a priori measured or estimated soil parameters with a clear physical meaning. We rely on the two-factor model of clay that takes into account the factors of capillarity and shrinkage. The key points of the model to be proposed are some weak pseudo shrinkage that the rigid soils demonstrate according to their experimental water retention curves, and some specific properties of the rigid grain matrix. The three input parameters for prediction of soil water retention with the rigid grain matrix include inter-grain porosity, as well as maximum and minimum grain sizes. The comparison between measured and predicted sand water retention curves for four different sands is promising.

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

    Energy Technology Data Exchange (ETDEWEB)

    Smith, David E.

    2000-09-14

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

  10. A new bounding-surface plasticity model for cyclic behaviors of saturated clay

    Science.gov (United States)

    Hu, Cun; Liu, Haixiao

    2015-05-01

    A new combined isotropic-kinematic hardening rule is proposed based on the concept of the generalized homological center and the generalization of Masing's rule. The key point of the new hardening rule is that the unloading event can be treated as if it were virgin loading through taking the stress reversal point as the new generalized homological center of the bounding surface. Therefore, a new simple bounding-surface plasticity model with three important features for the cyclic behaviors of saturated clay is developed. Firstly, according to the movement of the generalized homological center, the model can harden not only isotropically but also kinematically to account for the anisotropy and memory the particular loading events. Secondly, the continuous cyclic loading is divided into the first loading, unloading and reloading processes and they are treated differently when calculating the hardening modulus to describe the soil responses accurately. The third feature is taking the generalized homological center as the mapping origin in the mapping rule to reflect the plastic flow in the unloading event. The behaviors of saturated clay for the monotonic and cyclic stress-controlled and strain-controlled triaxial tests are simulated by the model. The prediction results show an encouraging agreement with the experimental data.

  11. Coupled hydro-mechanical model for expansive clays

    Science.gov (United States)

    Koudelka, Tomáš; Krejčí, Tomáš; Kruis, Jaroslav

    2017-07-01

    The paper deals with the hydro-mechanical model for expansive clayey soils. The complex model is based on the hypoplasticity, which parameters are influenced by suction, and additionally on Schrefler's model for saturated-unsaturated water flow in deforming porous medium. The model has been implemented into the open source software SIFEL and selected results of a simple numerical example are presented in the last section of the paper.

  12. BIB-SEM of representative area clay structures paving towards an alternative model of porosity

    Science.gov (United States)

    Desbois, G.; Urai, J. L.; Houben, M.; Hemes, S.; Klaver, J.

    2012-04-01

    A major contribution to understanding the sealing capacity, coupled flow, capillary processes and associated deformation in clay-rich geomaterials is based on detailed investigation of the rock microstructures. However, the direct characterization of pores in representative elementary area (REA) and below µm-scale resolution remains challenging. To investigate directly the mm- to nm-scale porosity, SEM is certainly the most direct approach, but it is limited by the poor quality of the investigated surfaces. The recent development of ion milling tools (BIB and FIB; Desbois et al, 2009, 2011; Heath et al., 2011; Keller et al., 2011) and cryo-SEM allows respectively producing exceptional high quality polished cross-sections suitable for high resolution porosity SEM-imaging at nm-scale and investigating samples under wet conditions by cryogenic stabilization. This contribution focuses mainly on the SEM description of pore microstructures in 2D BIB-polished cross-sections of Boom (Mol site, Belgium) and Opalinus (Mont Terri, Switzerland) clays down to the SEM resolution. Pores detected in images are statistically analyzed to perform porosity quantification in REA. On the one hand, BIB-SEM results allow retrieving MIP measurements obtained from larger sample volumes. On the other hand, the BIB-SEM approach allows characterizing porosity-homogeneous and -predictable islands, which form the elementary components of an alternative concept of porosity/permeability model based on pore microstructures. Desbois G., Urai J.L. and Kukla P.A. (2009) Morphology of the pore space in claystones - evidence from BIB/FIB ion beam sectioning and cryo-SEM observations. E-Earth, 4, 15-22. Desbois G., Urai J.L., Kukla P.A., Konstanty J. and Baerle C. (2011). High-resolution 3D fabric and porosity model in a tight gas sandstone reservoir: a new approach to investigate microstructures from mm- to nm-scale combining argon beam cross-sectioning and SEM imaging . Journal of Petroleum Science

  13. Aqueous dispersion of red clay-based ceramic powder with the addition of starch

    Directory of Open Access Journals (Sweden)

    Maria Victoria Alcantar Umaran

    2013-04-01

    Full Text Available The optimum dispersion and rheological properties of red clay-based ceramic suspension loaded with unary and binary starch were investigated in aqueous medium. The aqueous ceramic suspension was prepared consisting of red clay, quartz, feldspar, and distilled water. Using a polyelectrolyte dispersant (Darvan 821A, the ternary ceramic powder was initially optimized to give the smallest average particle size at 0.8 wt. (% dispersant dosage as supported by sedimentation test. This resulted into an optimum high solid loading of 55 wt. (%. The addition of either unary or binary starches to the optimized ceramic slurry increased the viscosity but maintained an acceptable fluidity. The mechanism of such viscosity increase was found to be due to an adsorption of starch granules onto ceramic surfaces causing tolerable agglomeration. Correspondingly, the rheological evaluations showed that the flow behaviors of all starch-loaded ceramic slurries can be described using Herschel-Bulkley model. The parameters from this model indicated that all ceramic slurries loaded with starch are shear thinning that is required for direct casting process.

  14. Modeling spatial variability of sand-lenses in clay till settings using transition probability and multiple-point geostatistics

    DEFF Research Database (Denmark)

    Kessler, Timo Christian; Nilsson, Bertel; Klint, Knud Erik;

    2010-01-01

    the geology of e.g. a contaminated site, it is not always possible to gather enough information to build a representative geological model. Mapping in analogue geological settings and applying geostatistical tools to simulate spatial variability of heterogeneities can improve ordinary geological models...... that are predicated only on vertical borehole information. This study documents methods to map geological heterogeneity in clay till and ways to calibrate geostatistical models with field observations. A well-exposed cross-section in an excavation pit was used to measure and illustrate the occurrence and distribution...... of sand-lenses in clay till. Sand-lenses mainly account for horizontal transport and are prioritised in this study. Based on field observations, the distribution has been modeled using two different geostatistical approaches. One method uses a Markov chain model calculating the transition probabilities...

  15. Common clay and shale

    Science.gov (United States)

    Virta, R.L.

    2011-01-01

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

  16. Statistical model for the structure and gelation of smectite clay suspensions

    NARCIS (Netherlands)

    Dijkstra, Marjolein; Hansen, J.P.; Madden, P.A.

    1997-01-01

    The sol-gel transition in a suspension of monodisperse, charged, disklike platelets ~Laponite, i.e., a synthetic clay! is examined within a simplified statistical model. The initial ‘‘primitive’’ model of uniformly charged disks surrounded by microscopic co ions and counterions is reduced to a model

  17. Modified Liu-Carter Compression Model for Natural Clays with Various Initial Water Contents

    Directory of Open Access Journals (Sweden)

    Sen Qian

    2016-01-01

    Full Text Available The initial water content has a significant effect on the compression behaviour of reconstituted clays. This effect has to be considered in the Liu-Carter model to ensure the addition voids ratio only related to soil structure. A modified Liu-Carter compression model is proposed by introducing the empirical equations for reconstituted clays at different initial water contents into the Liu-Carter model. The proposed model is verified against the experimental results from the literature. The simulations by the proposed method are also compared with that by old method where the influence of initial water content is not considered. The results show that the predicted virgin compression curves of natural clays are similar, but the values of b and Δey may be very different.

  18. Report on Modeling Coupled Processes in the Near Field of a Clay Repository

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Hui -Hai [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Houseworth, Jim [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Rutqvist, Jonny [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Li, Lianchong [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Asahina, Daisuke [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Chen, Fei [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Birkholzer, Jens [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2012-08-01

    Clay/shale has been considered as potential host rock for geological disposal of high-level radioactive waste throughout the world. Coupled thermal, hydrological, mechanical, and chemical (THMC) processes have a significant impact on the long-term safety of a clay repository. For example, the excavation damaged zone (EDZ) near repository tunnels can modify local permeability (resulting from induced fractures), potentially leading to less confinement capability. This report documents results from three R&D activities: (1) implementation and validation of constitutive relationships, (2) development of a discrete fracture network (DFN) model for investigating coupled processes in the EDZ, and (3) development of a THM model for the FE tests at Mont Terri, Switzerland, for the purpose of model validation. The overall objective of these activities is to provide an improved understanding of EDZ evolution in clay repositories and the associated coupled processes, and to develop advanced relevant modeling capabilities.

  19. Modified clay sorbents

    Energy Technology Data Exchange (ETDEWEB)

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

    1990-04-10

    This patent describes a clay-based sorbent. It comprises a clay having an external surface and lamellar layers; and cationic surfactant ions having a hydrocarbon portion and a cationic head portion, the cationic surfactant ions being irreversibly bound to the external surface by the hydrocarbon portion. This patent also describes cetylpyridinium-aluminum hydroxy-montmorillonite; the clay-based sorbent wherein the clay is a non-expandable clay; and the clay-based sorbent wherein the cationic surfactant ions are selected from the group consisting of ionized cetylpyridinium chloride and cetylakonium chloride.

  20. Modelling unfrozen water content in a silty clay permafrost deposit

    DEFF Research Database (Denmark)

    Agergaard, Frederik Ancker; Ingeman-Nielsen, Thomas

    2011-01-01

    The mechanical properties of both unfrozen soils and permafrost soils are influenced by the amount of unfrozen water in the pore space. When dealing with foundation engineering in permafrost areas it is essential to estimate the unfrozen water content (wu). This paper deals with the establishing...... of a calibration equation for determining the unfrozen water content of a Greenlandic silty clay permafrost deposit. Calibration experiments have been conducted for water contents in the interval 0 – 10 % at both 5 °C and 22 °C. Calibration equations are verified against permittivity data from a permafrost core...... of material properties similar to the test soil. The calibration for 5°C is seen to make a good fit to the permafrost core data. Further experiments should be performed in order to extend the range of water contents tested and hence the range of validity of the calibration equation....

  1. Screening of waste for use in clay-based bricks in the Arctic

    DEFF Research Database (Denmark)

    Belmonte, Louise Josefine; Ottosen, Lisbeth M.; Kirkelund, Gunvor Marie

    2014-01-01

    of hazardous waste, municipal solid waste incineration (MSWI) ashes and minetailings from Greenland, were investigated in order to determine their potential suitability for incorporationin the production of clay-based bricks. Furthermore, the MSWI fly ash was subjected to two remediation techniques...... and several studies have demonstrated that clay-based bricks and tiles can successfully accommodate waste types,such as incineration ashes, mine tailings and dredged harbour sediments (Zhang et al., 2011; Roy et al.,2007; Mezencevova et al., 2012). In the vulnerable Arctic environment, the impact......Clay-based ceramics, such as bricks, are heterogeneous materials, which can incorporate raw materials ofwide ranging compositions, without impairing their technical properties (Dondi et al., 1997a,b). Due to thisability, bricks have become a popular material in waste management research worldwide...

  2. Simulation of pesticide leaching in a cracking clay soil with the PEARL model

    NARCIS (Netherlands)

    Scorza, R.P.; Boesten, J.J.T.I.

    2005-01-01

    Testing of pesticide leaching models is important to increase confidence in their use in pesticide registration procedures world-wide. The chromatographic PEARL model was tested against the results of a field leaching study on a cracking clay soil with a tracer (bromide), a mobile pesticide (bentazo

  3. Electrical resistivity characteristics of diesel oil-contaminated kaolin clay and a resistivity-based detection method.

    Science.gov (United States)

    Liu, Zhibin; Liu, Songyu; Cai, Yi; Fang, Wei

    2015-06-01

    in kaolin clay normally had three kinds of effects including oil filling, coating, and bridging. Finally, a resistivity-based ANN model was established based on the database collected from the experiment data. The performance of the model was proved to be reasonably accepted, which puts forward a possible simple, economic, and effective tool to detect the oil content in contaminated clayey soils just with four basic parameters: wet density, dry density, measured moisture content, and electrical resistivity.

  4. Micromechanics of non-active clays in saturated state and DEM modelling

    Directory of Open Access Journals (Sweden)

    Pagano Arianna Gea

    2017-01-01

    Full Text Available The paper presents a conceptual micromechanical model for 1-D compression behaviour of non-active clays in saturated state. An experimental investigation was carried out on kaolin clay samples saturated with fluids of different pH and dielectric permittivity. The effect of pore fluid characteristics on one-dimensional compressibility behaviour of kaolin was investigated. A three dimensional Discrete Element Method (DEM was implemented in order to simulate the response of saturated kaolin observed during the experiments. A complex contact model was introduced, considering both the mechanical and physico-chemical microscopic interactions between clay particles. A simple analysis with spherical particles only was performed as a preliminary step in the DEM study in the elastic regime.

  5. Perch-height specific predation on tropical lizard clay models: implications for habitat selection in mainland neotropical lizards.

    Science.gov (United States)

    Steffen, John E

    2009-09-01

    Predation has been hypothesized to be a strong selective force structuring communities of tropical lizards. Comparisons of perch height and size-based predation frequencies can provide a unique window into understanding how predation might shape habitat selection and morphological patterns in lizards, especially anoles. Here I use plasticine clay models, placed on the trunks of trees and suspended in the canopy to show that predation frequency on clay models differs primarily according to habitat (canopy vs. trunk-ground), but not according to size. These data are discussed in light of observed lizard abundances in the lowland forests of Costa Rica, and are presented as partial explanation for why fewer lizards are found in tree canopies, and more lizards are found on ground-trunk habitats.

  6. CFD Modelling and Experimental Testing of Thermal Calcination of Kaolinite Rich Clay Particles - An Effort towards Green Concrete

    DEFF Research Database (Denmark)

    Gebremariam, Abraham Teklay

    Cement industry is one of the major industrial emitters of greenhouse gases, generating 5-7% of the total anthropogenic CO2 emissions. Consequently, use of supplementary cementitious materials (SCM) to replace part of the CO2-intensive cement clinker is an attractive way to mitigate CO2 emissions...... from cement industry. SCMs based on industrial byproducts like fly ashes and slags are subject to availability problems. Yet clays are the most ubiquitous material on earth's crust. Thus, properly calcined clays are a very promising candidate for SCMs to produce green cements. Calcination...... PROcess Modeling System) software, which is suspended during the project due to the adjustment made by the project consortium. The model results from both C++ and gPROMS software show good similarity. Various experiments have been performed to derive key kinetic data, to collect data from a gas suspension...

  7. Experimental Study and modelling of the Sorption of Selenite and Europium Onto Smectite and Illite Clays

    Energy Technology Data Exchange (ETDEWEB)

    Missana, T.; Alonso, U.; Garcia-Gutierrez, M.

    2009-10-12

    This study provides a large set of experimental selenite sorption data for pure smectite and illite. Similar sorption behavior existed in both clays: linear within a large range of the Se concentrations investigated and independent of ionic strength. Selenite sorption was also analysed in the illite/smectite system with the clays mixed in two different proportions. The objective of the study was to provide the simplest model possible to fit the experimental data, a model also capable of describing selenite sorption in binary illite/smectite clay systems. Selenite sorption data were modeled using both a one-and a two-site non-electrostatic model that took into account the formation of two complexes at the edge sites of the clay. The complexation constants obtained by fitting sorption data of the individual minerals were incorporated into a model to predict the adsorption of selenium in the illite/ smectite mixtures; the models predictions were consistent with the experimental adsorption data. (Author) 42 refs.

  8. Assessment of Calculation Procedures for Piles in Clay Based on Static Loading Tests

    DEFF Research Database (Denmark)

    Augustesen, Anders; Andersen, Lars

    2008-01-01

    Numerous methods are available for the prediction of the axial capacity of piles in clay. In this paper, two well-known models are considered, namely the current API-RP2A (1987 to present) and the recently developed ICP method. The latter is developed by Jardine and his co-workers at Imperial...

  9. Creating Clay Models of a Human Torso as an Alternative to Dissection

    Science.gov (United States)

    Shipley, Gwendolyn

    2010-01-01

    Instead of dissecting animals, students create small clay models of human internal organs to demonstrate their understanding of the positioning and interlocking shapes of the organs. Not only is this approach more environmentally friendly, it also forces them to learn human anatomy--which is more relevant to them than the anatomy of other…

  10. Clay Modeling versus Written Modules as Effective Interventions in Understanding Human Anatomy

    Science.gov (United States)

    Bareither, Mary Lou; Arbel, Vered; Growe, Meghan; Muszczynski, Emily; Rudd, Adam; Marone, Jane R.

    2013-01-01

    The effectiveness of clay modeling to written modules is examined to determine the degree of improvement in learning and retention of anatomical 3D relationships among students with different learning preferences. Thirty-nine undergraduate students enrolled in a cadaver dissection course completed a pre-assessment examination and the VARK…

  11. Multi scale modeling of the elastic properties of polymer-clay nanocomposites

    Science.gov (United States)

    Pahlavan Pour, Maryam

    Polymer-Clay Nanocomposites (PCN) are known to improve the mechanical properties of bulk polymers, even for modest clay loadings. This enhancement is due to the high aspect ratio and mechanical properties of the nanoclay platelets. Additionally, the interphase zone created by altered polymer chains in the vicinity of the nanoclays plays an important reinforcing role. Several analytical approaches exist for predicting the elastic properties of PCN, ranging from simplified two-step models to more complex one-step methods. However, no thorough study has yet rigorously verified the accuracy of these models. On the other hand, the numerical models that are commonly used to evaluate the analytical models are still far from modeling the real PCN microstructure reported in the literature. For example, most of the models have failed to model the detailed 3D microstructure considering randomly positioned reinforcing particles, the large nanoclay aspect ratio and the explicit incorporation of the constituent phases. More significantly, most of numerical studies have been reported without a thorough determination of the appropriate Representative Volume Element (RVE) due its computational burden, resulting in benchmark results of questionable accuracy. The main purpose of this thesis was to evaluate the accuracy of homogenization models for predicting the mechanical behavior of nanoclay nanocomposites. First, the validity of commonly used analytical micromechanical models for the prediction of exfoliated PCN elastic properties was evaluated with the help of 3D Finite Element (FE) simulations. In particular, special attention was devoted to the interphase around the nanoclays. The modeling strategy was a two-step procedure relying on the Effective Particle (EP) concept, in which the multi-layer reinforcing stacks were replaced by homogenized particles. The accuracy of the numerical models was guaranteed, within a given tolerance, by rigorous determination of the RVE. It was

  12. Multiphase flow and multicomponent reactive transport model of the ventilation experiment in Opalinus clay

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, L.; Samper, J.; Montenegro, L.; Major, J.C.

    2008-10-15

    During the construction and operational phases of a high-level radioactive waste (HLW) repository constructed in a clay formation, ventilation of underground drifts will cause desaturation and oxidation of the rock. The Ventilation Experiment (VE) was performed in a 1.3 m diameter unlined horizontal microtunnel on Opalinus clay at Mont Terri underground research laboratory in Switzerland to evaluate the impact of desaturation on rock properties. A multiphase flow and reactive transport model of VE is presented here. The model accounts for liquid, vapor and air flow, evaporation/condensation and multicomponent reactive solute transport with kinetic dissolution of pyrite and siderite and local-equilibrium dissolution/precipitation of calcite, ferrihydrite, dolomite, gypsum and quartz. Model results reproduce measured vapor flow, liquid pressure and hydrochemical data and capture the trends of measured relative humidities, although such data are slightly overestimated near the rock interface due to uncertainties in the turbulence factor. Rock desaturation allows oxygen to diffuse into the rock and triggers pyrite oxidation, dissolution of calcite and siderite, precipitation of ferrihydrite, dolomite and gypsum and cation exchange. pH in the unsaturated rock varies from 7.8 to 8 and is buffered by calcite. Computed changes in the porosity and the permeability of Opalinus clay in the unsaturated zone caused by oxidation and mineral dissolution/precipitation are smaller than 5%. Therefore, rock properties are not expected to be affected significantly by ventilation of underground drifts during construction and operational phases of a HLW repository in clay.

  13. Towards a numerical run-out model for quick-clay slides

    Science.gov (United States)

    Issler, Dieter; L'Heureux, Jean-Sébastien; Cepeda, José M.; Luna, Byron Quan; Gebreslassie, Tesfahunegn A.

    2015-04-01

    Highly sensitive glacio-marine clays occur in many relatively low-lying areas near the coasts of eastern Canada, Scandinavia and northern Russia. If the load exceeds the yield stress of these clays, they quickly liquefy, with a reduction of the yield strength and the viscosity by several orders of magnitude. Leaching, fluvial erosion, earthquakes and man-made overloads, by themselves or combined, are the most frequent triggers of quick-clay slides, which are hard to predict and can attain catastrophic dimensions. The present contribution reports on two preparatory studies that were conducted with a view to creating a run-out model tailored to the characteristics of quick-clay slides. One study analyzed the connections between the morphological and geotechnical properties of more than 30 well-documented Norwegian quick-clay slides and their run-out behavior. The laboratory experiments by Locat and Demers (1988) suggest that the behavior of quick clays can be reasonably described by universal relations involving the liquidity index, plastic index, remolding energy, salinity and sensitivity. However, these tests should be repeated with Norwegian clays and analyzed in terms of a (shear-thinning) Herschel-Bulkley fluid rather than a Bingham fluid because the shear stress appears to grow in a sub-linear fashion with the shear rate. Further study is required to understand the discrepancy between the material parameters obtained in laboratory tests of material from observed slides and in back-calculations of the same slides with the simple model by Edgers & Karlsrud (1982). The second study assessed the capability of existing numerical flow models to capture the most important aspects of quick-clay slides by back-calculating three different, well documented events in Norway: Rissa (1978), Finneidfjord (1996) and Byneset (2012). The numerical codes were (i) BING, a quasi-two-dimensional visco-plastic model, (ii) DAN3D (2009 version), and (iii) MassMov2D. The latter two are

  14. Simulation Of Enhanced Reductive Dechlorination For Remediation Of Tce In A Fractured Clay System: A New Model Approach And Application To Field Site

    DEFF Research Database (Denmark)

    Manoli, Gabriele; Chambon, Julie Claire Claudia; Christiansen, Camilla Maymann;

    2010-01-01

    with interspersed sand lenses and stringers. The transport model couples diffusion dominated transport in the clay matrix, with advective‐dispersive transport in the fractures and higher permeability sand lenses. The reactive model calculates sequential reductive dechlorination of TCE (trichloroethylene) to its...... a contamination of trichloroethylene located in a fractured clay till. The site is simulated using the model developed. Fracture geometry, site parameters and degradation rates are based on observations from the site and lab studies. The risk for drinking water is assessed and cleanup times are simulated using...

  15. Ball clay

    Science.gov (United States)

    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.

  16. Low resistivity oil(gas)-bearing reservoir conductive model --Dual water clay matrix conductive model in the north area of Tarim Basin, Xinjiang, China

    Institute of Scientific and Technical Information of China (English)

    潘和平; 王家映; 樊政军; 马勇; 柳建华; 李明强

    2001-01-01

    Shaly sands reservoir is one of the most distributive types of the oil(gas)-bearing reservoirs discovered in China, and low resistivity oil(gas)-bearing reservoirs are mostly shaly sands reservoirs. Therefore, shaly sands reservoir conductive model is the key to evaluate low resistivity oil(gas)-bearing reservoirs using logging information. Some defects were found when we studied the clay distribution type conductive model, dual-water conductive model, conductive rock matrix model, etc. Some models could not distinguish the conductive path and nature of microporosity water and clay water and some models did not consider the clay distribution type and the mount of clay volume. So, we utilize the merits,overcome the defects of the above models, and put forward a new shaly sands conductive model-dual water clay matrix conductive model (DWCMCM) in which dual water is the free water and the microporosity water in shaly sands and the clay matrix(wet clay) is the clay grain containing water. DWCMCM is presented here, the advantages of which can tell the nature and conductive path from different water (microporosity water and freewater), in consid-eration of the clay distribution type and the mount of clay volume in shaly sands. So, the results of logging interpretation in the oil(gas)-bearing reservoirs in the north of Tarim Basin area, China with DWCMCM are better than those interpreted by the above models.

  17. Learning Outcomes and Student-Perceived Value of Clay Modeling and Cat Dissection in Undergraduate Human Anatomy and Physiology

    Science.gov (United States)

    DeHoff, Mary Ellen; Clark, Krista L.; Meganathan, Karthikeyan

    2011-01-01

    Alternatives and/or supplements to animal dissection are being explored by educators of human anatomy at different academic levels. Clay modeling is one such alternative that provides a kinesthetic, three-dimensional, constructive, and sensory approach to learning human anatomy. The present study compared two laboratory techniques, clay modeling…

  18. Learning Outcomes and Student-Perceived Value of Clay Modeling and Cat Dissection in Undergraduate Human Anatomy and Physiology

    Science.gov (United States)

    DeHoff, Mary Ellen; Clark, Krista L.; Meganathan, Karthikeyan

    2011-01-01

    Alternatives and/or supplements to animal dissection are being explored by educators of human anatomy at different academic levels. Clay modeling is one such alternative that provides a kinesthetic, three-dimensional, constructive, and sensory approach to learning human anatomy. The present study compared two laboratory techniques, clay modeling…

  19. Geological modeling of a fault zone in clay rocks at the Mont-Terri laboratory (Switzerland)

    Science.gov (United States)

    Kakurina, M.; Guglielmi, Y.; Nussbaum, C.; Valley, B.

    2016-12-01

    Clay-rich formations are considered to be a natural barrier for radionuclides or fluids (water, hydrocarbons, CO2) migration. However, little is known about the architecture of faults affecting clay formations because of their quick alteration at the Earth's surface. The Mont Terri Underground Research Laboratory provides exceptional conditions to investigate an un-weathered, perfectly exposed clay fault zone architecture and to conduct fault activation experiments that allow explore the conditions for stability of such clay faults. Here we show first results from a detailed geological model of the Mont Terri Main Fault architecture, using GoCad software, a detailed structural analysis of 6 fully cored and logged 30-to-50m long and 3-to-15m spaced boreholes crossing the fault zone. These high-definition geological data were acquired within the Fault Slip (FS) experiment project that consisted in fluid injections in different intervals within the fault using the SIMFIP probe to explore the conditions for the fault mechanical and seismic stability. The Mont Terri Main Fault "core" consists of a thrust zone about 0.8 to 3m wide that is bounded by two major fault planes. Between these planes, there is an assembly of distinct slickensided surfaces and various facies including scaly clays, fault gouge and fractured zones. Scaly clay including S-C bands and microfolds occurs in larger zones at top and bottom of the Mail Fault. A cm-thin layer of gouge, that is known to accommodate high strain parts, runs along the upper fault zone boundary. The non-scaly part mainly consists of undeformed rock block, bounded by slickensides. Such a complexity as well as the continuity of the two major surfaces are hard to correlate between the different boreholes even with the high density of geological data within the relatively small volume of the experiment. This may show that a poor strain localization occurred during faulting giving some perspectives about the potential for

  20. Technetium diffusion in clay-based materials under oxic and anoxic conditions. AECL research No. AECL-11419

    Energy Technology Data Exchange (ETDEWEB)

    Hume, H.B.

    1995-12-31

    Describes experiments to determine diffusion coefficients for technetium in compacted clay-based material (soils) saturated with a synthetic groundwater solution whose principal ions were calcium, sodium, and chlorine. Tests were conducted in anoxic conditions established by conducting the experiments in a low- oxygen glove box and by mixing 0.5% by weight of powdered iron with the soils (Lake Agassiz clay and a 1:3 mix of dry mass of clay and crushed granite aggregate). Effective diffusion coefficients were also measured in oxic conditions in Avonlea bentonite, Lake Agassiz clay, and illite/smectite. Implications of the results for transport of radionuclides through backfill material and clay barriers used in underground disposal of nuclear fuel waste are discussed.

  1. Clay Play

    Science.gov (United States)

    Rogers, Liz; Steffan, Dana

    2009-01-01

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

  2. Coupled THMC models for bentonite in clay repository for nuclear waste

    Science.gov (United States)

    Zheng, L.; Rutqvist, J.; Birkholzer, J. T.; Li, Y.; Anguiano, H. H.

    2015-12-01

    Illitization, the transformation of smectite to illite, could compromise some beneficiary features of an engineered barrier system (EBS) that is composed primarily of bentonite and clay host rock. It is a major determining factor to establish the maximum design temperature of the repositories because it is believed that illitization could be greatly enhanced at temperatures higher than 100 oC and thus significantly lower the sorption and swelling capacity of bentonite and clay rock. However, existing experimental and modeling studies on the occurrence of illitization and related performance impacts are not conclusive, in part because the relevant couplings between the thermal, hydrological, chemical, and mechanical (THMC) processes have not been fully represented in the models. Here we present fully coupled THMC simulations of a generic nuclear waste repository in a clay formation with bentonite-backfilled EBS. Two scenarios were simulated for comparison: a case in which the temperature in the bentonite near the waste canister can reach about 200 oC and a case in which the temperature in the bentonite near the waste canister peaks at about 100 oC. The model simulations demonstrate that illitization is in general more significant at higher temperatures. We also compared the chemical changes and the resulting swelling stress change for two types of bentonite: Kunigel-VI and FEBEX bentonite. Higher temperatures also lead to much higher stress in the near field, caused by thermal pressurization and vapor pressure buildup in the EBS bentonite and clay host rock. Chemical changes lead to a reduction in swelling stress, which is more pronounced for Kunigel-VI bentonite than for FEBEX bentonite.

  3. Behavior of instrumented model batter piles in clay

    Energy Technology Data Exchange (ETDEWEB)

    Narasimha Rao, S.; Veeresh, C. [Indian Inst. of Technology, Madras (India). Ocean Engineering Centre

    1995-12-31

    Pile foundations in several coastal and offshore structures are subjected to significant amounts of lateral loads due to wave action. Usually batter piles are adopted to resist large lateral loads. In this investigation an attempt has been made to study the behavior of batter pile in clayey soils through an experimental program carried out on instrumented model aluminium piles of 26 mm diameter in a test tank of size, 1,200 mm x 800mm x 1,100 mm. The pile was instrumented with electrical resistance type strain gauges to determine the bending moment variations along the depth of embedment of pile. Bending moment vis depth relationships were used to determine the Soil reaction (p) and lateral displacement (y) along the length of the pile for the applied load. From the bending moment vs depth curves it is found that depth of maximum bending moment is greater for negative batter pile than for vertical and positive batter pile. The data of soil reaction and lateral displacement against depth can be used to develop p-y relationships which are useful in the design of laterally loaded piles.

  4. A 'putty-practically-clay' vintage model with R and D driven biases in energy-saving technical change

    Energy Technology Data Exchange (ETDEWEB)

    Van Zon, A.; Lontzek, T.

    2005-07-01

    This paper deals with the problem of tackling the adverse effect of output growth on environmental quality. For this purpose we use an intermediate sector that builds 'putty-practically-clay' capital consisting of an energy-raw capital amalgam used for final goods production. The putty-practically-clay model is a strongly simplified version of a full putty-clay model, that mimics all the relevant behaviour of a full puttyclay model, but that does not entail the administrative hassle of a full putty-clay vintage model. In addition to this, we introduce an R and D sector that develops renewable- and conventional energy-based technologies. The allocation of R and D activities over these two uses of R and D gives rise to an induced bias in technical change. In the context of our model, this implies that technological progress is primarily driven by the desire to counteract the upward pressure on production cost implied by a continuing price increase of conventional energy resources. Hotelling's rule suggests that this price rise is unavoidable in the face of the ongoing depletion of conventional energy reserves. By means of some illustrative model simulations we study the effects of energy policy on the dynamics of the model for alternative policy options aimed at achieving GHG emission reductions. We identify the conditions under which energy policy might partly backfire and present some non-standard policy implications.

  5. Modeling Air Permeability in Variably Saturated Soil from Two Natural Clay Gradients

    DEFF Research Database (Denmark)

    Chamindu, Deepagoda T K K; Arthur, Emmanuel; Møldrup, Per

    2013-01-01

    Understanding soil–gas phase properties and processes is important for finding solutions to critical environmental problems such as greenhouse gas emissions and transport of gaseous-phase contaminants in soils. Soil–air permeability, ka (μm2), is the key parameter governing advective gas movement...... in soil and is controlled by soil physical characteristics representing soil texture and structure. Models predicting ka as a function of air-filled porosity (ɛ) often use a reference-point measurement, for example, ka,1000 at ɛ1000 (where the measurement is done at a suction of –1000 cm H2O). Using ka...... measurements from two Danish arable fields, each located on natural clay gradients, this study presents a pore tortuosity–disconnectivity analysis to characterize the soil–gas phase. The main objective of this study is to investigate the effect of soil–moisture condition, clay content, and other potential...

  6. Montmorillonite Clay-Based Polyurethane Nanocomposite As Local Triamcinolone Acetonide Delivery System

    Directory of Open Access Journals (Sweden)

    Flávia Carmo Horta Pinto

    2011-01-01

    Full Text Available Biodegradable polyurethane was synthesized by preparing aqueous polyurethane dispersion having poly(caprolactone and poly(ethylene glycol as soft segments. Montmorillonite particles were delaminated within the waterborne polyurethane to produce a nanocomposite. The triamcinolone acetonide (TA, an important corticoid drug, was dispersed into the nanocomposite followed by a drying step to produce an implantable drug delivery system. Infrared (FTIR results demonstrated that the original chemical structure of the TA was preserved after incorporation into the nanocomposite. Wide angle (WAXS and small angle X-ray scattering (SAXS results suggested that TA and clay do not dramatically change the morphology phase of the polymer although they can interact with each other. The presence of montmorillonite particles in the nanocomposite reduced the rate of TA release as compared to the pure polyurethane and enhanced the mechanical properties of the polymer. The overall results indicate that montmorillonite clay-based polyurethane nanocomposite could be potentially applied as local TA delivery system.

  7. Production of building elements based on alkali-activated red clay brick waste

    Directory of Open Access Journals (Sweden)

    Rafael Andres Robayo-Salazar

    2016-09-01

    Full Text Available This paper analyzes the feasibility of reusing a red clay brick waste (RCBW in order to produce building elements such as blocks, pavers and tiles, by using the technique of alkaline activation. The production of these building elements was based on the design of a hybrid mortar with 48.61 MPa of compressive strength, at 28 curing days at room temperature (25 °C. The hybrid mortar was synthesized by adding 10% by weight of Portland cement (OPC to the RCBW, Red Clay Brick Waste. As alkaline activators were used commercial industrial grade sodium hydroxide (NaOH and sodium silicate (Na2SiO3. Building elements were physically and mechanically characterized, according to Colombian Technical Standards (NTC. This technology process is presented as an alternative for the reuse of RCBW and its contribution to the environmental sustainability.

  8. Ball clay

    Science.gov (United States)

    Virta, R.L.

    2011-01-01

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

  9. Bio-Based Nano Composites from Plant Oil and Nano Clay

    Science.gov (United States)

    Lu, Jue; Hong, Chang K.; Wool, Richard P.

    2003-03-01

    We explored the combination of nanoclay with new chemically functionalized, amphiphilic, plant oil resins to form bio-based nanocomposites with improved physical and mechanical properties. These can be used in many new applications, including the development of self-healing nanocomposites through controlled reversible exfoliation/intercalation, and self-assembled nano-structures. Several chemically modified triglyceride monomers of varying polarity, combined with styrene (ca 30include acrylated epoxidized soybean oil (AESO), maleated acrylated epoxidized soybean oil (MAESO) and soybean oil pentaerythritol glyceride maleates (SOPERMA), containing either hydroxyl group or acid functionality or both. The clay used is a natural montmorillonite modified with methyl tallow bis-2-hydroxyethyl quaternary ammonium chloride, which has hydroxyl groups. Both XRD and TEM showed a completely exfoliated structure at 3 wtwhen the clay content is above 5 wtconsidered a mix of intercalated and partially exfoliated structure. The controlled polarity of the monomer has a major effect on the reversible dispersion of clay in the polymer matrix. The bio-based nanocomposites showed a significant increase in flexural modulus and strength. Supported by EPA and DoE

  10. Modeling multi-component transport and enhanced anaerobic dechlorination processes in a single fracture-clay matrix system

    DEFF Research Database (Denmark)

    Chambon, Julie Claire Claudia; Broholm, Mette Martina; Binning, Philip John;

    2010-01-01

    and the contaminant flux out of the clay system are assessed for different distributions of microbial degradation. Results from a set of scenarios show that time to remove 90% of the initial mass is halved when dechlorination occurs in a 5 cm reaction zone in the clay at the fracture-matrix interface (from 419 to 195...... to the physical processes, mainly diffusion in the matrix, than to the biogeochemical processes, when dechlorination is assumed to take place in a limited reaction zone only. The inclusion of sequential dechlorination in clay fracture transport models is crucial, as the contaminant flux to the aquifer...... of a contaminant in a single fracture-clay matrix system coupled with a reactive model for anaerobic dechlorination. The model takes into account microbially driven anaerobic dechlorination, where sequential Monod kinetics with competitive inhibition is used to model the reaction rates, and degradation...

  11. Modeling sorption and diffusion of organic sorbate in hexadecyltrimethylammonium-modified clay nanopores - a molecular dynamics simulation study.

    Science.gov (United States)

    Zhao, Qian; Burns, Susan E

    2013-03-19

    Organoclays are highly sorptive engineered materials that can be used as amendments in barrier systems or geosynthetic liners. The performance of confining and isolating the nonpolar organic contaminants by those barrier/lining systems is essentially controlled by the process of organic contaminant mass transport in nanopores of organoclays. In this article, we use molecular dynamics (MD) simulations to study the sorption and diffusion of organic sorbates in interlayers of sodium montmorillonite and hexadecyltrimethylammonium (HDTMA(+))-modified montmorillonite clays. Simulated system consisted of the clay framework, interlayer organic cation, water, and organic sorbate. Their interactions were addressed by the combined force field of ClayFF, constant-valence force field, and SPC water model. Simulation results indicated that in HDTMA coated clay nanopores, diffusion of nonpolar species benzene was slowed because they were subjected to influence of both the pore wall and the HDTMA surfactant. This suggested the nonpolar organic compound diffusion in organophilic clays can be affected by molecular size of diffusive species, clay pore size, and organic surfactant loading. Additionally, a model that connected the diffusion rate of organic compounds in the bulk organoclay matrix with macropores and nanopores was established. The impact of intercalated organic cations on the diffusion dominated mass transport of organic compounds yielded insight into the prediction of the apparent diffusion behavior of organic compounds in organic-modified clays.

  12. Assessing the interactions of a natural antibacterial clay with model Gram-positive and Gram-negative human pathogens

    Science.gov (United States)

    Londono, S. C.; Williams, L. B.

    2013-12-01

    The emergence of antibiotic resistant bacteria and increasing accumulations of antibiotics in reclaimed water, drive the quest for new natural antimicrobials. We are studying the antibacterial mechanism(s) of clays that have shown an ability to destroy bacteria or significantly inhibit their growth. One possible mode of action is from soluble transition metal species, particularly reduced Fe, capable of generating deleterious oxygen radical species. Yet another possibility is related to membrane damage as a consequence of physical or electrostatic interaction between clay and bacteria. Both mechanisms could combine to produce cell death. This study addresses a natural antibacterial clay from the NW Amazon basin, South America (AMZ clay). Clay mineralogy is composed of disordered kaolinite (28.9%), halloysite (17.8%) illite (12%) and smectite (16.7%). Mean particle size is 1.6μm and total and specific surface area 278.82 and 51.23 m2/g respectively. The pH of a suspension (200mg/ml) is 4.1 and its Eh is 361mV after 24h of equilibration. The ionic strength of the water in equilibrium with the clay after 24 h. is 6 x10-4M. These conditions, affect the element solubility, speciation, and interactions between clay and bacteria. Standard microbiological methods were used to assess the viability of two model bacteria (Escherichia coli and Bacillus subtilis) after incubation with clay at 37 degC for 24 hrs. A threefold reduction in bacterial viability was observed upon treatment with AMZ clay. We separated the cells from the clay using Nycodenz gradient media and observed the mounts under the TEM and SEM. Results showed several membrane anomalies and structural changes that were not observed in the control cells. Additionally, clay minerals appeared in some places attached to cell walls. Experiments showed that exchanging AMZ clay with KCl caused loss of antibacterial property. Among the exchangeable -and potentially toxic- ions we measured Al+3, Cu+2, Zn+2, Ba+2 and Co+2

  13. Experimental and modeling study of flash calcination of kaolinite rich clay particles in a gas suspension calciner

    DEFF Research Database (Denmark)

    Gebremariam, Abraham Teklay; Yin, Chungen; Rosendahl, Lasse;

    2015-01-01

    Calcination of kaolinite particles under appropriate conditions to produce materials that can replace part of the CO2 intensive clinker is gaining an increasing interest in cement industry worldwide. This paper presents a study of flash calcination of kaolinite rich clay particles in a pilot scale...... gas suspension calciner, with the aim to derive useful guidelines on smart calcination for obtaining products of the best pozzolanic properties. Calcination tests are performed in the calciner under six different operation conditions. The raw feed and the calcined clay samples are all characterized...... experimentally and a mathematical model is also developed to predict the conversion of the clay particles. The model properly accounts for the particle–ambient flow interaction and numerically solves all the processes occurring within the clay particles. The model predictions are compared against...

  14. Alumina-clay nanoscale hybrid filler assembling in cross-linked polyethylene based nanocomposites: mechanics and thermal properties.

    Science.gov (United States)

    Jose, Josmin P; Thomas, Sabu

    2014-07-28

    Herein, investigation on XLPE-Al2O3-clay ternary hybrid systems of Al2O3 and clay in 1 : 1 and 2 : 1 ratios, binary systems of XLPE-clay and XLPE-Al2O3 nanocomposites, with special reference to the hybrid filler effect and the superior microstructural development in ternary systems is conducted. The ternary hybrid composite of Al2O3 and clay in a 1 : 1 ratio exhibits the highest tensile strength (100% increase) and Young's modulus (208% increase), followed by the Al2O3 : clay = 2 : 1 system. The interaction between alumina and clay altered the composite morphology, filler dispersion and gave rise to a unique filler architecture leading to a substantial boost up in mechanics compared to predictions based on the idealized filler morphology. Experimentally observed much higher mechanics compared to theoretical predictions confirmed that the dramatic improvement in mechanics is the outcome of the positive hybrid effect and a second factor of synergism, i.e. filler-filler networks. Morphological control of the hybrid filler network is realized by adjusting the ratio between different fillers. For the Al2O3 : clay = 2 : 1 system, the microstructural limitation of dispersion due to the steric effect of alumina clusters shifts the properties to the negative hybrid effect region.

  15. Modelling on the Equilibrium, Kinetics and Thermodynamics for Zinc (II Ions Removal from Solution by “Aloji” Kaolinite Clay

    Directory of Open Access Journals (Sweden)

    G. K. Akpomie

    2014-09-01

    Full Text Available This study reports the use of Aloji kaolinite clay as an adsorbent for Zinc (II ions from solution. The aim of this research was the use of the kaolinite mineral as a low cost adsorbent for the removal of zinc (II ions from aqueous stream. The adsorption was performed by the use of batch method and the dependence of pH, initial metal ion concentration, contact time and temperature on adsorption were investigated. Maximum adsorption of zinc ions was achieved at an optimum pH of 4.0. Equilibrium sorption was achieved within 60 minutes of the experiment. Equilibrium sorption data were analyzed by the Langmuir and Freundlich isotherm. The Freundlich isotherm gave a better fit to the data than the Langmuir isotherm based on the comparison of their linear regression R2 values. Kinetic studies revealed the applicability of the Pseudo-second order kinetic model than the Pseudo-first order model based on their R2 values. Thermodynamic parameters such as changes in Gibbs free energy, ΔG0, enthalpy, ΔH0 and entropy, ΔS0 were evaluated and showed the adsorption process to be spontaneous, feasible and exothermic in nature. These results showed the potential of Aloji kaolinite clay as a suitable low-cost adsorbent for Zinc (II ions from aqueous stream

  16. Simulation of water movement and isoproturon behaviour in a heavy clay soil using the MACRO model

    Directory of Open Access Journals (Sweden)

    T. J. Besien

    1997-01-01

    Full Text Available In this paper, the dual-porosity MACRO model has been used to investigate methods of reducing leaching of isoproturon from a structured heavy clay soil. The MACRO model was applied to a pesticide leaching data-set generated from a plot scale experiment on a heavy clay soil at the Oxford University Farm, Wytham, England. The field drain was found to be the most important outflow from the plot in terms of pesticide removal. Therefore, this modelling exercise concentrated on simulating field drain flow. With calibration of field-saturated and micropore saturated hydraulic conductivity, the drain flow hydrographs were simulated during extended periods of above average rainfall, with both the hydrograph shape and peak flows agreeing well. Over the whole field season, the observed drain flow water budget was well simulated. However, the first and second drain flow events after pesticide application were not simulated satisfactorily. This is believed to be due to a poor simulation of evapotranspiration during a period of low rainfall around the pesticide application day. Apart from an initial rapid drop in the observed isoproturon soil residue, the model simulated isoproturon residues during the 100 days after pesticide application reasonably well. Finally, the calibrated model was used to show that changes in agricultural practice (deep ploughing, creating fine consolidated seed beds and organic matter applications could potentially reduce pesticide leaching to surface waters by up to 60%.

  17. Using mixture design of experiments to assess the environmental impact of clay-based structural ceramics containing foundry wastes

    Energy Technology Data Exchange (ETDEWEB)

    Coronado, M. [Department of Chemistry and Process and Resources Engineering, University of Cantabria, 39005 Santander (Spain); Department of Materials and Ceramics Engineering (CICECO), University of Aveiro, 3810-193 Aveiro (Portugal); Segadães, A.M. [Department of Materials and Ceramics Engineering (CICECO), University of Aveiro, 3810-193 Aveiro (Portugal); Andrés, A., E-mail: andresa@unican.es [Department of Chemistry and Process and Resources Engineering, University of Cantabria, 39005 Santander (Spain)

    2015-12-15

    Highlights: • Modelling of the environmental risk in terms of clay and by-products contents. • M-DoE and response surface plots enable quick comparison of three ceramic processes. • Basicity of the mixture increases the leaching, especially at low firing temperatures. • Liquid phase content plays a major role decreasing the leaching of Cr and Mo. • Together, M-DoE and phase diagrams enable better prediction of pollutants leaching. - Abstract: This work describes the leaching behavior of potentially hazardous metals from three different clay-based industrial ceramic products (wall bricks, roof tiles, and face bricks) containing foundry sand dust and Waelz slag as alternative raw materials. For each product, ten mixtures were defined by mixture design of experiments and the leaching of As, Ba, Cd, Cr, Cu, Mo, Ni, Pb, and Zn was evaluated in pressed specimens fired simulating the three industrial ceramic processes. The results showed that, despite the chemical, mineralogical and processing differences, only chrome and molybdenum were not fully immobilized during ceramic processing. Their leaching was modeled as polynomial equations, functions of the raw materials contents, and plotted as response surfaces. This brought to evidence that Cr and Mo leaching from the fired products is not only dependent on the corresponding contents and the basicity of the initial mixtures, but is also clearly related with the mineralogical composition of the fired products, namely the amount of the glassy phase, which depends on both the major oxides contents and the firing temperature.

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

    OpenAIRE

    Hideo Hashizume

    2015-01-01

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

  19. Clay Houses

    Science.gov (United States)

    Pedro, Cathy

    2011-01-01

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

  20. ALKALI-ACTIVATED CEMENT MORTARS CONTAINING RECYCLED CLAY-BASED CONSTRUCTION AND DEMOLITION WASTE

    OpenAIRE

    Puertas, F.; Santos, R.; Alonso M. M.; Del Rio M.

    2015-01-01

    The use of clay-based waste as an aggregate for concrete production is an amply studied procedure. Nonetheless, research on the use of this recycled aggregate to prepare alkaline cement mortars and concretes has yet to be forthcoming. The present study aimed to determine: the behaviour of this waste as a pozzolan in OPC systems, the mechanical strength in OPC, alkali-activated slag (AAS) and fly ash (AAFA) mortars and the effect of partial replacement of the slag and ash themselves with groun...

  1. Regional aquifer geochemistry below the Boom Clay (NE-Belgium): data analysis and modelling

    Science.gov (United States)

    Vandersteen, Katrijn; Leterme, Bertrand

    2014-05-01

    For more than 35 years, SCK•CEN has been investigating the possibility of high-level and/or long-lived radioactive waste disposal in the Boom Clay in NE-Belgium, including the study of the regional hydrogeology and geochemistry of the aquifer systems surrounding the Boom Clay. This study presents the analysis and modelling of groundwater geochemistry in the confined aquifers below the Boom Clay in NE-Belgium. This so-called deep aquifer system includes, with increasing depth, parts of the Oligocene Aquifer System, The Bartoon Aquitard System and the Ledo-Paniselian-Brusselian Aquifer System. At the end of the Neogene period, during which several marine transgressions and regressions took place, the sea definitely drew back after having deposited shallow marine and estuarine sands and some clay. The original seawater in the pores of the sediments was in first instance gradually diluted as the aquifer was flushed by recharge (fresh) water. Afterwards, water-rock interactions, including cation exchange, began to play a role in the deep aquifer system. This led to changes in groundwater composition over time. Geochemical data (major ions, stable isotopes, radioactive isotopes, dissolved gases) have been collected at a regional scale from the piezometric network in the deep aquifer system. Several measurement campaigns have been performed between 1980 and 2010. Groundwater is currently mainly of Na-HCO3 to Na-Cl type water, and because of the low groundwater velocity, re-equilibration with the host formations generally occurs. The main geochemical indicators (salinity, stable isotopes) point to a mixture between saline water (to the NW) and fresh recharge water (from SE). SE-NW gradients of ion concentrations are observed and can be explained in agreement with the pattern of natural groundwater flow. Building on the concepts emerging from the geochemical data analysis and recent groundwater modelling, a geochemical model was developed in PhreeqC, using geochemical and

  2. How mobile are sorbed cations in clays and clay rocks?

    Science.gov (United States)

    Gimmi, T; Kosakowski, G

    2011-02-15

    Diffusion of cations and other contaminants through clays is of central interest, because clays and clay rocks are widely considered as barrier materials for waste disposal sites. An intriguing experimental observation has been made in this context: Often, the diffusive flux of cations at trace concentrations is much larger and the retardation smaller than expected based on their sorption coefficients. So-called surface diffusion of sorbed cations has been invoked to explain the observations but remains a controversial issue. Moreover, the corresponding surface diffusion coefficients are largely unknown. Here we show that, by an appropriate scaling, published diffusion data covering a broad range of cations, clays, and chemical conditions can all be modeled satisfactorily by a surface diffusion model. The average mobility of sorbed cations seems to be primarily an intrinsic property of each cation that follows inversely its sorption affinity. With these surface mobilities, cation diffusion coefficients can now be estimated from those of water tracers. In pure clays at low salinities, surface diffusion can reduce the cation retardation by a factor of more than 1000.

  3. Electrochemical energy storage in montmorillonite K10 clay based composite as supercapacitor using ionic liquid electrolyte.

    Science.gov (United States)

    Maiti, Sandipan; Pramanik, Atin; Chattopadhyay, Shreyasi; De, Goutam; Mahanty, Sourindra

    2016-02-15

    Exploring new electrode materials is the key to realize high performance energy storage devices for effective utilization of renewable energy. Natural clays with layered structure and high surface area are prospective materials for electrical double layer capacitors (EDLC). In this work, a novel hybrid composite based on acid-leached montmorillonite (K10), multi-walled carbon nanotube (MWCNT) and manganese dioxide (MnO2) was prepared and its electrochemical properties were investigated by fabricating two-electrode asymmetric supercapacitor cells against activated carbon (AC) using 1.0M tetraethylammonium tetrafluroborate (Et4NBF4) in acetonitrile (AN) as electrolyte. The asymmetric supercapacitors, capable of operating in a wide potential window of 0.0-2.7V, showed a high energy density of 171Whkg(-1) at a power density of ∼1.98kWkg(-1). Such high EDLC performance could possibly be linked to the acid-base interaction of K10 through its surface hydroxyl groups with the tetraethylammonium cation [(C2H5)4N(+) or TEA(+)] of the ionic liquid electrolyte. Even at a very high power density of 96.4kWkg(-1), the cells could still deliver an energy density of 91.1Whkg(-1) exhibiting an outstanding rate capability. The present study demonstrates for the first time, the excellent potential of clay-based composites for high power energy storage device applications.

  4. Chloride ions promoted the catalytic wet peroxide oxidation of phenol over clay-based catalysts.

    Science.gov (United States)

    Zhou, Shiwei; Zhang, Changbo; Xu, Rui; Gu, Chuantao; Song, Zhengguo; Xu, Minggang

    2016-01-01

    Catalytic wet peroxide oxidation (CWPO) of phenol over clay-based catalysts in the presence and absence of NaCl was investigated. Changes in the H2O2, Cl(-), and dissolved metal ion concentration, as well as solution pH during phenol oxidation, were also studied. Additionally, the intermediates formed during phenol oxidation were detected by liquid chromatography-mass spectroscopy and the chemical bonding information of the catalyst surfaces was analyzed by X-ray photoelectron spectroscopy (XPS). The results showed that the presence of Cl(-) increased the oxidation rate of phenol to 155%, and this phenomenon was ubiquitous during the oxidation of phenolic compounds by H2O2 over clay-based catalysts. Cl(-)-assisted oxidation of phenol was evidenced by several analytical techniques such as mass spectroscopy (MS) and XPS, and it was hypothesized that the rate-limiting step was accelerated in the presence of Cl(-). Based on the results of this study, the CWPO technology appears to be promising for applications in actual saline phenolic wastewater treatment.

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

    Science.gov (United States)

    Hashizume, Hideo

    2015-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Hideo Hashizume

    2015-02-01

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

  7. Fire and Gas Barrier Properties of Poly(styrene-co-acrylonitrile Nanocomposites Using Polycaprolactone/Clay Nanohybrid Based-Masterbatch

    Directory of Open Access Journals (Sweden)

    S. Benali

    2008-01-01

    Full Text Available Exfoliated nanocomposites are prepared by dispersion of poly(ε-caprolactone (PCL grafted montmorillonite nanohybrids used as masterbatches in poly(styrene-co-acrylonitrile (SAN. The PCL-grafted clay nanohybrids with high inorganic content are synthesized by in situ intercalative ring-opening polymerization of ε-caprolactone between silicate layers organomodified by alkylammonium cations bearing two hydroxyl functions. The polymerization is initiated by tin alcoholate species derived from the exchange reaction of tin(II bis(2-ethylhexanoate with the hydroxyl groups borne by the ammonium cations that organomodified the clay. These highly filled PCL nanocomposites (25 wt% in inorganics are dispersed as masterbatches in commercial poly(styrene-co-acrylonitrile by melt blending. SAN-based nanocomposites containing 3 wt% of inorganics are accordingly prepared. The direct blend of SAN/organomodified clay is also prepared for sake of comparison. The clay dispersion is characterized by wide-angle X-ray diffraction (WAXD, atomic force microscopy (AFM, and solid state NMR spectroscopy measurements. The thermal properties are studied by thermogravimetric analysis. The flame retardancy and gas barrier resistance properties of nanocomposites are discussed both as a function of the clay dispersion and of the matrix/clay interaction.

  8. Preparation of nanocomposites polyurethane water bone with clay montmorillonite sodica and organophilic clay;Preparacao de nanocompositos a base de dispersoes aquosas de poliuretano com argilas hidrofilica e organofilica

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, Claudia P. [Sunchemical do Brasil Ltda., Rio de Janeiro, RJ (Brazil); Delpech, Marcia C.; Coutinho, Fernanda M.B.; Mello, Ivana L. [Universidade do Estado do Rio de Janeiro (IQ/UERJ), RJ (Brazil). Inst. de Quimica

    2009-07-01

    Nanocomposites based on water bone polyurethane (NWPU's) were synthesized based on poli(propylene glycol), dimethylolpropionic acid (DMPA), isophorone diisocyanate (IPDI) and hydrazine (HYD), as chain extender. Two kinds of clays were employed: hydrophilic and organophilic. The nanocomposites were characterized by infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electronic microscopy (SEM) and the mechanical properties were evaluated. The FTIR results showed the presence of specific groups of clay and the XRD suggested that occurred their intercalation/exfoliation through polyurethane matrix. The mechanical resistance of the systems showed significant increase when compared to water dispersions synthesized without clay. (author)

  9. Electrical properties of multiphase composites based on carbon nanotubes and an optimized clay content

    Science.gov (United States)

    Egiziano, Luigi; Lamberti, Patrizia; Spinelli, Giovanni; Tucci, Vincenzo; Guadagno, Liberata; Vertuccio, Luigi

    2016-05-01

    The experimental results concerning the characterization of a multiphase nanocomposite systems based on epoxy matrix, loaded with different amount of multi-walled carbon nanotubes (MWCNTs) and an optimized Hydrotalcite (HT) clay content (i.e. 0.6 wt%), duly identified by an our previous theoretical study based on Design of Experiment (DoE), are presented. Dynamic-mechanical analysis (DMA) reveal that even the introduction of higher HT loading (up to 1%wt) don't affect significantly the mechanical properties of the nanocomposites while morphological investigations show an effective synergy between clay and carbon nanotubes that leads to peculiar micro/nanostructures that favor the creation of the electrical conductive network inside the insulating resin. An electrical characterization is carried out in terms of DC electrical conductivity, percolation threshold (EPT) and frequency response in the range 10Hz-1MHz. In particular, the measurements of the DC conductivity allow to obtain the typical "percolation" curve also found for classical CNT-polymer mixtures and a value of about 2 S/m for the electrical conductivity is achieved at the highest considered CNTs concentration (i.e. 1 wt%). The results suggest that multiphase nanocomposites obtained incorporating dispersive nanofillers, in addition to the conductive one, may be a valid alternative to the polymer blends, to improve the properties of the polymeric materials thus able to meet high demands, particularly concerning their mechanical and thermal stability and electrical features required in the aircraft engineering.

  10. ALKALI-ACTIVATED CEMENT MORTARS CONTAINING RECYCLED CLAY-BASED CONSTRUCTION AND DEMOLITION WASTE

    Directory of Open Access Journals (Sweden)

    F. Puertas

    2015-09-01

    Full Text Available The use of clay-based waste as an aggregate for concrete production is an amply studied procedure. Nonetheless, research on the use of this recycled aggregate to prepare alkaline cement mortars and concretes has yet to be forthcoming. The present study aimed to determine: the behaviour of this waste as a pozzolan in OPC systems, the mechanical strength in OPC, alkali-activated slag (AAS and fly ash (AAFA mortars and the effect of partial replacement of the slag and ash themselves with ground fractions of the waste. The pozzolanic behaviour of clay-based waste was confirmed. Replacing up to 20 % of siliceous aggregate with waste aggregate in OPC mortars induced a decline in 7 day strength (around 23 wt. %. The behaviour of waste aggregate in AAMs mortars, in turn, was observed to depend on the nature of the aluminosilicate and the replacement ratio used. When 20 % of siliceous aggregate was replaced by waste aggregate in AAS mortars, the 7 day strength values remained the same (40 MPa. In AAFA mortars, waste was found to effectively replace both the fly ash and the aggregate. The highest strength for AAFA mortars was observed when they were prepared with both a 50 % replacement ratio for the ash and a 20 % ratio for the aggregate.

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

    Science.gov (United States)

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

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

    Science.gov (United States)

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

  13. Modelling coupled chemico-osmotic and advective-diffusive transport of nitrate salts in the Callovo-Oxfordian Clay

    Science.gov (United States)

    Baechler, S.; Croisé, J.; Altmann, S.

    2012-12-01

    Chemico-osmosis is a recognized phenomenon taking place in clay mineral-rich sedimentary formations and a number of questions have been raised concerning its potential effects on pressure fields in and around underground radioactive waste repositories installed in such formations. Certain radioactive waste packages contain large quantities of nitrate salts whose release might result in the presence of highly concentrated salt solutions in the disposal cells, during their resaturation after closure of the facility. This would lead to large solute concentration gradients within the formation's porewater which could then potentially induce significant chemico-osmotic fluxes. In this paper, we assess the impact of chemico-osmotic fluxes on the water pressure during the post-closure period of a typical disposal cell for intermediate-level, long-lived bituminised radioactive waste in the Callovo-Oxfordian Clay formation. A numerical model of chemico-osmotic water flow and solute transport has been developed based on the work of Bader and Kooi (2005) [5], and including Bresler's dependence of osmotic efficiency on concentration and compaction state [9]. Model validity has been extended to highly concentrated solutions by incorporating a concentration-dependent activity coefficient, based on the Pitzer's equations. Results show that due to the strong dependence of the osmotic coefficient on concentration, the impact of chemico-osmosis on water flow and on the pressure field around the disposal cell is relatively low. A maximum overpressure of the order of 1 MPa was obtained. No difference in the simulation results were noticed for disposal cell solutions having concentrations higher than 1 M NaNO3. Differences between simulations were found to be almost entirely due to Bresler's relationship i.e., the model of the dependence between osmotic efficiency and concentration, and only slightly on the activity coefficient correction. Questions remain regarding the appropriate

  14. Optimization of organo clay production for applications in based oil drilling fluid; Otimizacao do processo de organofilizacao para aplicacoes em fluidos de perfuracao base oleo

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Heber S.; Martins, Alice B.; Costa, Danubia L. da; Ferreira, Heber C.; Neves, Gelmires de A.; Melo, Tomas J.A. de [Universidade Federal de Campina Grande (UFCG), PB (Brazil); Teixeira Neto, Erico [Universidade Federal do ABC (UFABC), Santo Andre, SP (Brazil)

    2008-07-01

    The organophilic clays are widely used as an agent dispersed in the composition of oil based drilling fluids. The organophilic clays are gotten from bentonite clays treated, in watery way, with ionic surfactants, that are adsorbed in the surface of interlayer of the clays, re-covered them with a organic layer. A fundamental stage of production of the organophilic clays is the dispersion of bentonite clays, in way that variables like: speed of agitation, temperature and time of cure, influences directly in plastic and apparent viscosities of these dispersions, together with other variables of organophilization process, like, temperature and time of cure of organophilization, has direct influence in efficiency of the organophilization process. This work considers a study of these variable, using bentonite clays: Brasgel PA{sup R} and Cloisite Na{sup +R}, treated with the ionic surfactant Praepagem WB{sup R}. The organophilic clays gotten had been characterized by rays X diffraction, Foster's swelling, and the results were compared with the commercial organophilic clay VG-69{sup R}, industrially treated with ionic surfactant. Viscosities plastic and apparent of the dispersions had been measured in the midst of organic dispersant diesel oil used to obtain the oil based drilling fluids. Preliminary results of Foster's swelling and preparation of fluids show that the clays have affinity with the means liquid organic dispersants, and the fluids meet specifications of PETROBRAS (N-22581-1997 and N-2259 to 1997) for use in the of diesel oil based drilling fluids. (author)

  15. Properties and applications of polymer nanocomposites clay and carbon based polymer nanocomposites

    CERN Document Server

    Prasad Sahoo, Bibhu

    2017-01-01

    The aim of the present edited book is to furnish scientific information about manufacturing, properties, and application of clay and carbon based polymer nanocomposites. It can be used as handbook for undergraduate and post graduate courses (for example material science and engineering, polymer science and engineering, rubber technology, manufacturing engineering, etc.) as well as as reference book for research fellows and professionals. Polymer nanocomposites have received outstanding importance in the present decade because of their broad range of high-performance applications in various areas of engineering and technology due to their special material properties. A great interest is dedicated to nanofiller based polymeric materials, which exhibit excellent enhancement in macroscopic material properties (mechanical, thermal, dynamic mechanical, electrical and many more) at very low filler contents and can therefore be used for the development of next-generation composite materials.

  16. Antimicrobial nanocomposites based on natural modified materials: a review of carbons and clays.

    Science.gov (United States)

    Martynková, Grazyna Simha; Valásková, Marta

    2014-01-01

    The review is focused on the recent research and development of antimicrobial nanocomposites based on selected carbon nanomaterials and natural nanoclay minerals. The nanocomposites comprised of two or several components, where at least one presents antimicrobial properties, are discussed. Yet the most popular agent remains silver as nanoparticle or in ionic form. Second, broadly studied group, are organics as additives or polymeric matrices. Both carbons and clays in certain forms possess antimicrobial properties. A lot of interest is put on to research graphene oxide. The low-environmental impact technologies-based on sustainable biopolymers have been studied. Testing of antimicrobial properties of nanomaterials is performed most frequently on E. coli and S. aureus bacterias.

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

    Science.gov (United States)

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

    2006-09-01

    The sorption of Eu(III) onto kaolinite and montmorillonite was investigated up to 150 °C. The clays were purified samples, saturated with Na in the case of montmorillonite. Batch experiments were conducted at 25, 40, 80 and 150 °C in 0.5 M NaClO 4 solutions to measure the distribution coefficients (Kd) of Eu as a trace element (<10 -6 mol/L) between the solution and kaolinite. For the Na-montmorillonite, we used Kd results from a previous study [Tertre, E., Berger, G., Castet, S., Loubet, M., Giffaut, E., 2005. Experimental study of adsorption of Ni 2+, Cs + and Ln 3+ onto Na-montmorillonite up to 150 °C. Geochim. Cosmochim. Acta69, 4937-4948] obtained under exactly the same conditions. The number and nature of the Eu species sorbed onto both clay minerals were investigated by time resolved laser fluorescence spectroscopy (TRLFS) in specific experiments in the same temperature range. We identified a unique inner-sphere complex linked to the aluminol sites in both clays, assumed to be dbnd AlOEu 2+ at the edge of the particles, and a second exchangeable outer-sphere complex for montmorillonite, probably in an interlayer position. The Kd values were used to adjust the parameters of a surface complexation model (DLM: diffuse layer model) from 25 to 150 °C. The number of Eu complexes and the stoichiometry of reactions were constrained by TRLFS. The acidity constants of the amphoteric aluminol sites were taken from another study [Tertre, E., Castet, S., Berger, G., Loubet, M., Giffaut, E. Acid/base surface chemistry of kaolinite and Na-montmorillonite at 25 and 60 °C: experimental study and modelling. Geochim. Cosmochim. Acta, in press], which integrates the influence of the negative structural charge of clays on the acid/base properties of edge sites as a function of temperature and ionic strength. The results of the modelling show that the observed shift of the sorption edge towards low pH with increasing temperature results solely from the contribution of the

  18. Effect of Aluminum Source on Adsorption Performance of Lithium Orthosilicate Based Adsorbents from Kaolin Clay

    Institute of Scientific and Technical Information of China (English)

    XIE; Hongyan; DING; Tong; LI; Yulong; MA; Zhi; CHEN; Weiqiang

    2015-01-01

    A novel lithium orthosilicate based adsorbent doping with halloysite nanotubes(HNTs) was synthesized with Kaolin clay and SiO2 by an impregnation-precipitation method.The samples were characterized by X-ray diffraction and scanning electron microscopy,nitrogen adsorption-desorption isotherm analysis and thermo-gravimetry,respectively.The results indicate that the reactivity of Li4SiO4 for CO2 absorption can be enhanced by doping alumina.Different aluminum sources result in different degrees of the CO2 adsorption performance.It is also found that the CO2 capture amount of the adsorbent doping with Halloysite nanotubes is 15.25 wt.%at 560 ℃,which is better than that of the adsorbent doping with γ-Al2O3(i.e.,10.88 wt.%).

  19. Effect of Aluminum Source on Adsorption Performance of Lithium Orthosilicate Based Adsorbents from Kaolin Clay

    Institute of Scientific and Technical Information of China (English)

    XIE Hongyan; DING Tong; LI Yulong; MA Zhi; CHEN Weiqiang

    2015-01-01

    A novel lithium orthosilicate based adsorbent doping with halloysite nanotubes (HNTs) was synthesized with Kaolin clay and SiO2 by an impregnation-precipitation method. The samples were characterized by X-ray diffraction and scanning electron microscopy, nitrogen adsorption-desorption isotherm analysis and thermo-gravimetry, respectively. The results indicate that the reactivity of Li4SiO4 for CO2 absorption can be enhanced by doping alumina. Different alu-minum sources result in different degrees of the CO2 adsorption performance. It is also found that the CO2 capture amount of the adsorbent doping with Halloysite nanotubes is 15.25wt.% at 560℃, which is better than that of the ad-sorbent doping withγ-Al2O3(i.e., 10.88wt.%).

  20. Self-healing coatings based on halloysite clay polymer composites for protection of copper alloys.

    Science.gov (United States)

    Abdullayev, Elshad; Abbasov, Vagif; Tursunbayeva, Asel; Portnov, Vasiliy; Ibrahimov, Hikmat; Mukhtarova, Gulbaniz; Lvov, Yuri

    2013-05-22

    Halloysite clay nanotubes loaded with corrosion inhibitors benzotriazole (BTA), 2-mercaptobenzimidazole (MBI), and 2-mercaptobenzothiazole (MBT) were used as additives in self-healing composite paint coating of copper. These inhibitors form protective films on the metal surface and mitigate corrosion. Mechanisms involved in the film formation have been studied with optical and electron microscopy, UV-vis spectrometry, and adhesivity tests. Efficiency of the halloysite lumen loading ascended in the order of BTA paint layer for a long time and release was enhanced in the coating defects exposed to humid media with 20-50 h, sufficient for formation of protective layer. Anticorrosive performance of the halloysite-based composite acrylic and polyurethane coatings have been demonstrated for 110-copper alloy strips exposed to 0.5 M aqueous NaCl for 6 months.

  1. Simulation and model comparison of unsaturated movement of pesticides from a large clay lysimeter.

    NARCIS (Netherlands)

    Vink, J.P.M.; Gottesbüren, B.; Diekkrüger, B.; Zee, van der S.E.A.T.M.

    1997-01-01

    A long-term (>10 months) leaching experiment was conducted with a large clay soil column and a rain simulator to study unsaturated transport of the nematicide aldicarb and the herbicide simazine in a cracked clay soil. Water retention and soil conductivity were derived from experimental outflow data

  2. Magnitude, modeling and significance of swelling and shrinkage processes in clay soils.

    NARCIS (Netherlands)

    Bronswijk, J.J.B.

    1991-01-01

    The dynamic process of swelling and shrinkage in clay soils has significant practical consequences, such as the rapid transport of water and solutes via shrinkage cracks to the subsoil, and the destruction of buildings and roads on clay soils. In order to develop measuring methods and computer simul

  3. Water and clay based drilling fluids for oil wells; Fluidos hidroargilosos para perfuracao de pocos de petroleo

    Energy Technology Data Exchange (ETDEWEB)

    Medeiros, R.C.A. de; Amorim, L.V.; Santana, L.N. de L. [Universidade Federal de Campina Grande (UFCG), PB (Brazil)], e-mail: nalealves@hotmail.com

    2008-07-01

    In the onshore drilling of wells are commonly used aqueous fluids containing bentonite clays. However, to perform their functions generally there is the necessity of additives to drilling fluids, like viscositying, filtered reducer and lubricant. Thus, this work aims to develop water and clay base drilling fluids with low solid text, and with polymeric and lubricants additives. Were studied a sample of industrialized sodium bentonite clays, three polymeric compounds in the ternary form and a sample of lubricant, in different concentrations. Were determined the flow curves, the apparent and plastic viscosities, the yield limit and gel force in Fann 35A viscometer, the filtered volume in API filter-press and the lubricity coefficient in Ofite lubricimeter. The results showed that the fluid had pseudoplastic behavior, the polymeric additives adjusts their rheological properties and filtration and the addition of 1% of lubricant is sufficient to improve the lubricity of fluids. (author)

  4. Nanoindentation Characterization of a Ternary Clay-Based Composite Used in Ancient Chinese Construction

    Directory of Open Access Journals (Sweden)

    Dongwei Hou

    2016-10-01

    Full Text Available Ternary clay-based composite material (TCC, composed of lime, clay and sand, and usually modified with sticky rice and other organic compounds as additives, was widely used historically in Chinese construction and buildings due to its high mechanical performance. In this study, to gain an insight into the micromechanical mechanism of this cementitious material, the nanomechanical properties and volume fraction of mechanically different phases of the binder matrix are derived from the analysis of grid nanoindentation tests. Results show that there are five distinct mechanical phases, where the calcium silicate hydrate (C-S-H and geopolymer present in the binder matrix are almost identical to those produced in ordinary Portland cement (OPC and alkali-activated fly-ash geopolymer materials in nano-mechanical performance. The nano-mechanical behavior of calcite produced by the carbonation of lime in this binder is close to the calcite porous outer part of some sea urchin shells. Compared to OPC, the C-S-H contained in the TCC has a relatively lower ratio of indentation modulus to indentation hardness, implying a relatively lower resistance to material fracture. However, the geopolymer and calcite, at nearly the same volume content as the C-S-H, help to enhance the strength and durability of the TCC by their higher energy resistance capacity or higher strength compared to the C-S-H. Rediscovering of TCC offers a potential way to improve modern concrete’s strength and durability through synergy of multi-binders and the addition of organic materials if TCC can be advanced in terms of its workability and hardening rate.

  5. Confined wetting of FoCa clay powder/pellet mixtures: Experimentation and numerical modeling

    Science.gov (United States)

    Maugis, Pascal; Imbert, Christophe

    Potential geological nuclear waste disposals must be properly sealed to prevent contamination of the biosphere by radionuclides. In the framework of the RESEAL project, the performance of a bentonite shaft seal is currently studied at Mol (Belgium). This paper focuses on the hydro-mechanical physical behavior of centimetric, unsaturated samples of the backfilling material - a mixture of FoCa-clay powder and pellets - during oedometer tests. The hydro-mechanical response of the samples is observed experimentally, and then compared to numerical simulations performed by our Cast3M Finite Element code. The generalized Darcy’s law and the Barcelona Basic Model mechanical model formed the physical basis of the numerical model and the interpretation. They are widely used in engineered barriers modeling. Vertical swelling pressure and water intake were measured throughout the test. Although water income presents a monotonous increase, the swelling pressure evolution is marked by a peak, and then a local minimum before increasing again to an asymptotic value. This unexpected behavior is explained by yielding rather than by heterogeneity. It is satisfactorily reproduced by the model after parameter calibration. Several samples with different heights ranging from 5 to 12 cm show the same hydro-mechanical response, apart from a dilatation of the time scale. The interest of the characterization of centimetric samples to predicting the efficiency of a metric sealing is discussed.

  6. Project Opalinus Clay: Sorption Data Bases For Opalinus Clay Influenced By A High pH Plume

    Energy Technology Data Exchange (ETDEWEB)

    Bradbury, M.H.; Baeyens, B

    2004-11-01

    The interaction of groundwater with the large quantities of cement/concrete used in the construction and backfilling of emplacement tunnels containing long-lived intermediate level radioactive waste may give rise to the release of a pulse of hyper alkaline fluid (pH plume) into the surrounding rock. Since the pH of this plume could remain in excess of 12.5 for tens of thousands of years, many minerals in a sedimentary host rock would be unstable leading to dissolution reactions, secondary mineral precipitation and changes in groundwater chemistry. An Opalinus day formation in the Zuercher Weinland, is under consideration by Nagra as a potential host rock for a repository of spent fuel (SF), vitrified high-level waste (HLW) from reprocessing of spent fuel and long-lived intermediate-Ievel radioactive waste (ILW). The purpose of this report is to assess the effects of the interactions between a pH plume and Opalinus day on the sorption properties of the formation and to provide appropriate sorption data bases. (author)

  7. Determination of the photocatalytic activity of TiO2 coatings on clay roofing tile substrates methylene blue as model pollutant

    Directory of Open Access Journals (Sweden)

    Skapin Andrea S.

    2009-01-01

    Full Text Available The photocatalytically active mesoporous coatings, based on titanium dioxide sols (Degussa, of the fired clay roofing tiles substrate were prepared by using poly(ethylene glycol (PEG M-600 and M-4000, as the structure directing agents. The coatings were deposited using spray technique followed by thermal treatment. Photocatalytic activity of the TiO2 coatings was evaluated by aqueous solution of methylene blue as model dye, deposited on the top of the coatings, after irradiation with UV light. The results were compared with the photocatalytic efficiency of some commercial self-cleaning products (clay roofing tiles, glass. The newly design coatings showed an interesting decolourisation performance (over 30 % after 24 h. It appeared that the procedure of photocatalytic activity determination, in the case of porous substrates, should be renewed by a preadsorption process.

  8. An Evidence-Based Review on medicinal value of clays in traditional Persian medicine.

    Science.gov (United States)

    Hosseinkhani, Ayda; Montaseri, Hashem; Hosamo, Ammar; Zarshenas, Mohammad M

    2016-10-07

    The use of earths and clays for medical purposes dates back to antiquity. In recent years, there has been an increasing interest in researches on traditional remedies in the hope of discovering new drug. Iran is an ancient country with a medical backbone acquired from the experiences of ancient Persian scholars, who had made a great contribution to the development of the medical sciences. Many medical and pharmaceutical books by early Persian scientists still exist and may have the potential of leading researchers to new drug discoveries. Owing to the emergence of new and antimicrobial-resistant infections, present-day medicine has recently begun focusing on medicinal earths and clays especially as mineral antimicrobials. The current study is, therefore, aimed at gathering information regarding medicinal clays in traditional Persian medicine (TPM). Five main Persian materia medica with the key word 'tin' (clay) and current databases such as PubMed, Scopus, ScienceDirect, and Google Scholar were searched by key words 'white, green, red, maroon, violet, black, grey and pink clays' and 'pharmacological effects'. Twenty three clays were found in Persian manuscripts. Although their mineralogical compositions are unknown, different pharmacological properties have been attributed to these mineral medicaments. Clay's properties were widely used in medieval times for the treatment of infections to poisoning. They were also used in compound formulations, possibly for their pharmaceutical formulation modifying effects. Modern scientific proofs have also been found of many of the medicinal clays reported in Persian manuscripts. Although many of reported clays are still unknown, their characterization may lead to new medicinal developments. Novel analytical methods available today makes it possible to elucidate the chemical compositions of these minerals as parameters responsible for their medicinal effects.

  9. Constitutive model for unsaturated clays considering temperature effects%考虑温度影响的非饱和土本构模型

    Institute of Scientific and Technical Information of China (English)

    姚仰平; 牛雷; 杨一帆; 崔文杰; 胡贺祥

    2011-01-01

    首先建立了反映温度对非饱和土前期固结压力影响的加载-升温(loading thermal,LT)屈服线,而后基于真强度概念并结合潜在强度的确定方法推导出不同温度下非饱和黏土临界状态应力比的理论计算公式;将LT屈服线与反映常温下吸力对土体前期固结压力影响的加载-湿陷(loading collapse,LC)屈服线结合,建立了加载-升温-湿陷(loading thermal collapse,LTC)屈服面,该屈服面综合考虑了温度和吸力对土前期固结压力的影响;最后在临界土力学框架内建立了一个考虑温度影响的正常固结非饱和土本构模型,并将其扩展到超固结非饱和土.与巴塞罗那模型相比,所提出的模型仅增加了一个参数来反映非饱和土的前期固结压力随温度升高而降低的特性.模型能够综合描述温度、吸力以及不固超固结程度对土应力、应变的影响,方便于数值计算和有限元分析.模型预测和试验分析表明,某一固定吸力下升温会使正常固结非饱和土强度提高;对于超固结非饱和土,升温或湿化均会破坏土体超固结,降低软化和剪胀的效果.%The loading thermal (LT) yield curve is first introduced to consider the effects of temperature on the preconsolidation pressure change for unsaturated clays. Based on the concept of true strength and the calculation method of the potential failure stress ratio, the equation of the critical state stress ratio for unsaturated clays under different temperatures is deduced. The LT yield curve is then combined with the loading collapse (LC) yield curve which is used to consider the effects of suction on the preconsolidation pressure change for unsaturated clays, by which the loading thermal collapse (LTC) yield surface is presented. Therefore, the effects of both temperature and suction on the preconsolidation pressure change are considered by the LTC yield surface. After that, a constitutive model for normally consolidated

  10. Clay nanocomposites based on poly(vinylidene fluoride-co-hexafluoropropylene): Structure and properties

    KAUST Repository

    Kelarakis, Antonios

    2010-01-01

    Structure-properties relationships in poly(vinylidene fluoride-co-hexafluoropropylene), PVDF-HFP, clay nanocomposites are reported for the first time. Addition of organically modified clays to PVDF-HFP promotes an α to β transformation of the polymer crystals. The degree of transformation depends on the nature of the clay surface modifier and scales with the strength of the interactions between the clay and the polymer. The nanocomposites exhibit significant increases in elongation to failure compared to the neat copolymer. In addition, their dielectric permittivity is higher over a wide temperature range. Their mechanical and dielectric properties scale similar to the amount of the β phase present in the nanocomposites. © 2009 Elsevier Ltd. All rights reserved.

  11. Clays in natural and engineered barriers for radioactive waste confinement

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2007-07-01

    The meeting covers all topics concerning natural argillaceous geological barriers and the clay material based engineered barrier systems, investigated by means of: laboratory experiments on clay samples (new analytical developments), in situ experiments in underground research laboratories, mock-up demonstrations, natural analogues, as well as numerical modelling and global integration approaches (including up-scaling processes and treatment of uncertainties). The works presented deal with: examples of broad research programs (national or international) on the role of natural and artificial clay barriers for radionuclide confinement; clay-based repository concepts: repository designs, including technological and safety issues related to the use of clay for nuclear waste confinement; geology and clay characterisation: mineralogy, sedimentology, paleo-environment, diagenesis, dating techniques, discontinuities in rock clay, fracturing, self sealing processes, role of organic matter and microbiological processes; geochemistry: pore water geochemistry, clay thermodynamics, chemical retention, geochemical modelling, advanced isotopic geochemistry; mass transfer: water status and hydraulic properties in low permeability media, pore space geometry, water, solute and gas transfer processes, colloid mediated transport, large scale movements, long-term diffusion; alteration processes: oxidation effects, hydration-dehydration processes, response to thermal stress, iron-clay interactions, alkaline perturbation; geomechanics: thermo-hydro-mechanical behaviour of clay, rheological models, EDZ characterisation and evolution, coupled behaviour and models (HM, THM, THMC). A particular interest is given to potential contributions coming from fields of activities other than radioactive waste management, which take advantage of the confinement properties of the clay barrier (oil and gas industries, gas geological storage, CO{sub 2} geological sequestration, chemical waste isolation

  12. Extent of Corcoran Clay modified from Page (1986) for the Central Valley Hydrologic Model (CVHM)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This digital dataset defines the areal extent of the Corcoran Clay Member of the Tulare Formation. The complex hydrologic system of the Central Valley is simulated...

  13. Mechanical and electrical properties of a polyester resin reinforced with clay-based fillers

    Energy Technology Data Exchange (ETDEWEB)

    Buncianu, Dorel; Jadaneant, Mihai [UPT Timisoara, Timisoara (Romania); Tessier-Doyen, Nicolas; Absi, Joseph [Centre Européen de la Céramique, Limoges Cedex (France); Courreges, Fabien [Laboratoire XLIM, 123, Limoges Cedex (France)

    2017-03-15

    In this study, composite polymer-based materials were fabricated, in which a significant proportion of polyester resin was substituted by low-cost and environmentally-friendly clay-based raw materials. The main objective is to improve mechanical properties while maintaining a reasonable electrical insulating behavior. A homogenized distribution of fillers within the matrix compatible with the processing parameters was obtained up to a maximum added fraction of 20 vol%. Mechanical characterization using uniaxial traction tests and Charpy impact pendulum machine showed that stress-to-rupture can be enhanced of approximately 25 %. In addition, fracture energy was doubled for the best formulation. Dielectric constant was decreased and loss factor was slightly increased when electrical resistivity remained almost constant. In general, the composite materials with metakaolin fillers exhibited higher mechanical properties and greater electrical insulating behavior. Microstructural observation showed the presence of decohesive agglomerates of particles at the interface with the matrix. The mechanical properties were found to be more sensitive than electrical properties to the homogeneity of filler dispersion in the matrix.

  14. Modeling of Coupled Thermo-Hydro-Mechanical Processes with Links to Geochemistry Associated with Bentonite-Backfilled Repository Tunnels in Clay Formations

    Science.gov (United States)

    Rutqvist, Jonny; Zheng, Liange; Chen, Fei; Liu, Hui-Hai; Birkholzer, Jens

    2014-01-01

    This paper presents simulation results related to coupled thermal-hydraulic-mechanical (THM) processes in engineered barrier systems (EBS) and clay host rock, in one case considering a possible link to geochemistry. This study is part of the US DOE Office of Nuclear Energy's used fuel disposition campaign, to investigate current modeling capabilities and to identify issues and knowledge gaps associated with coupled THMC processes and EBS-rock interactions associated with repositories hosted in clay rock. In this study, we simulated a generic repository case assuming an EBS design with waste emplacement in horizontal tunnels that are back-filled with bentonite-based swelling clay as a protective buffer and heat load, derived for one type of US reactor spent fuel. We adopted the Barcelona basic model (BBM) for modeling of the geomechanical behavior of the bentonite, using properties corresponding to the FEBEX bentonite, and we used clay host rock properties derived from the Opalinus clay at Mont Terri, Switzerland. We present results related to EBS host-rock interactions and geomechanical performance in general, as well as studies related to peak temperature, buffer resaturation and thermally induced pressurization of host rock pore water, and swelling pressure change owing to variation of chemical composition in the EBS. Our initial THM modeling results show strong THM-driven interactions between the bentonite buffer and the low-permeability host rock. The resaturation of the buffer is delayed as a result of the low rock permeability, and the fluid pressure in the host rock is strongly coupled with the temperature changes, which under certain circumstances could result in a significant increase in pore pressure. Moreover, using the BBM, the bentonite buffer was found to have a rather complex geomechanical behavior that eventually leads to a slightly nonuniform density distribution. Nevertheless, the simulation shows that the swelling of the buffer is functioning to

  15. Adsorption of Amino Acids and Glutamic Acid-Based Surfactants on Imogolite Clays.

    Science.gov (United States)

    Bonini, Massimo; Gabbani, Alessio; Del Buffa, Stefano; Ridi, Francesca; Baglioni, Piero; Bordes, Romain; Holmberg, Krister

    2017-03-07

    Aluminum oxide surfaces are of utmost interest in different biotech applications, in particular for their use as adjuvants (i.e., booster of the immune response against infectious agents in vaccines production). In this framework, imogolite clays combine the chemical flexibility of an exposed alumina surface with 1D nanostructure. This work reports on the interaction between amino acids and imogolite, using turbidimetry, ζ-potential measurements, and Fourier transform infrared spectroscopy as main characterization tools. Amino acids with different side chain functional groups were investigated, showing that glutamic acid (Glu) has the strongest affinity for the imogolite surface. This was exploited to prepare a composite material made of a synthetic surfactant bearing a Glu polar head and a hydrophobic C12 alkyl tail, adsorbed onto the surface of imogolite. The adsorption of a model drug (rhodamine B isothiocyanate) by the hybrid was evaluated both in water and in physiological saline conditions. The findings of this paper suggest that the combination between the glutamate headgroup and imogolite represents a promising platform for the fabrication of hybrid nanostructures with tailored functionalities.

  16. Hydrogenolysis of Glycerol to 1,2-Propanediol Over Clay Based Catalysts.

    Science.gov (United States)

    Lee, Sang-Yong; Jung, Jae-Sun; Yang, Eun-Hyeok; Lee, Kwan-Young; Moon, Dong Ju

    2015-11-01

    1,2-propanediol (1,2-PDO) is one of the promising product among the valuable products derived from glycerol and it can be obtained by the catalytic hydrogenolysis of glycerol. Copper-supported clay-based catalysts were prepared with different pore sizes using various ratios of kaolin, Mg, and Al by coprecipitation and applied in the selective hydrogenolysis of glycerol to 1,2-PDO. In recent research, variations of pore volume and pore size could affect the diffusion of reagents within the catalyst due to the collision between reagents or pore wall and reagents. It changes selectivities of each product in hydrogenolysis of glycerol reaction. The physico-chemical properties of the catalysts were analyzed by XRD, N2 physisorption, TPR, CO2-TPD, SEM, and a mercury porosimeter. The Cu/TALCITE 4 catalyst showed 98% 1,2-PDO selectivity with 65% glycerol conversion under the optimized condition of 190 degrees C, 25 bar, and 20 wt% glycerol aqueous solution. It was found that the basic strength and meso-macro pore structure of the catalysts play an important role in glycerol conversion and 1,2-PDO selectivity.

  17. Multifunctional nanocarrier based on clay nanotubes for efficient intracellular siRNA delivery and gene silencing.

    Science.gov (United States)

    Wu, Hui; Shi, Yinfeng; Huang, Chusen; Zhang, Yang; Wu, Jiahui; Shen, Hebai; Jia, Nengqin

    2014-04-01

    RNA interference-mediated gene silencing relating to disease has recently emerged as a powerful method in gene therapy. Despite the promises, effective transport of siRNA with minimal side effects remains a challenge. Halloysites are cheap and naturally available aluminosilicate clay nanotubes with high mechanical strength and biocompatibility. In this study, a novel multifunctional nanocarrier based on functionalized halloysite nanotubes (f-HNTs) has been developed via electrostatic layer-by-layer assembling approach for loading and intracellular delivery of therapeutic antisurvivin siRNA and simultaneously tracking their intracellular transport, in which PEI-modified HNTs are used as gene vector, antisurvivin siRNA as gene therapeutic agent, and mercaptoacetic acid-capped CdSe quantum dots as fluorescent labeling probes. The successful assembly of the f-HNTs-siRNA complexes was systematically characterized by transmission electron microscopy (TEM), UV-visible spectrophotometry, Zeta potential measurement, fluorescence spectrophotometry, and electrochemical impedance spectroscopy. Confocal microscopy, biological TEM, and flow cytometry studies revealed that the complexes enabled the efficient intracellular delivery of siRNA for cell-specific gene silencing. MTT assays exhibited that the complexes can enhance antitumor activity. Furthermore, Western blot analysis showed that f-HNTs-mediated siRNA delivery effectively knocked down gene expression of survivin and thereby decreased the levels of target proteins of PANC-1 cells. Therefore, this study suggested that the synthesized f-HNTs were a new effective drug delivery system for potential application in cancer gene therapy.

  18. Perch-height specific predation on tropical lizard clay models: implications for habitat selection in mainland neotropical lizards

    Directory of Open Access Journals (Sweden)

    John E Steffen

    2009-09-01

    Full Text Available Predation has been hypothesized to be a strong selective force structuring communities of tropical lizards. Comparisons of perch height and size-based predation frequencies can provide a unique window into understanding how predation might shape habitat selection and morphological patterns in lizards, especially anoles. Here i use plasticine clay models, placed on the trunks of trees and suspended in the canopy to show that predation frequency on clay models differs primarily according to habitat (canopy vs. trunk-ground, but not according to size. These data are discussed in light of observed lizard abundances in the lowland forests of Costa Rica, and are presented as partial explanation for why fewer lizards are found in tree canopies, and more lizards are found on ground-trunk habitats. Rev. Biol. Trop. 57 (3: 859-864. Epub 2009 September 30.Existe la hipótesis de que la depredación es una fuerte fuerza selectiva que estructura las comunidades de lagartijas tropicales. Las comparaciones de las frecuencias de altura de la percha y de depredación con base en el tamaño pueden proveer una ventana única en el entendimiento de cómo la depredación podría moldear la selección del hábitat y los patrones morfológicos en las lagartijas, especialmente anoles. En este estudio uso modelos de plasticina, ubicados en troncos de árboles y suspendidos en el dosel para mostrar que la frecuencia de depredación en los modelos de plasticina difiere primariamente según el hábitat (dosel vs. tronco-suelo pero no según el tamaño. Estos datos se discuten a la luz de las abundancias de lagartijas observadas en los bosques de bajura de Costa Rica, y se presentan como una explicación parcial a porqué menos lagartijas se encuentran en los doseles, y más lagartijas se encuentran en los hábitats suelo-tronco.

  19. An update on synthetic dyes adsorption onto clay based minerals: A state-of-art review.

    Science.gov (United States)

    Ngulube, Tholiso; Gumbo, Jabulani Ray; Masindi, Vhahangwele; Maity, Arjun

    2017-04-15

    Dyes are growing to be a problematic class of pollutants to the environment. The disposal of dyes in water resources has bad aesthetic and health effects, hence the need to remove them from the environment. The need for treatment methods that are effective and low in price is rising hence a lot of research interest is being diverted towards adsorbents that are cheap, preferable naturally occurring materials like clays. In most reported dye adsorption studies, limited information on the relationship between characterization results with adsorbent performance on dye removal has been given. This review article seeks to report on the link between the adsorption characteristics of the clays and their adsorption capacities and to gather information on the modifications done on clays to improve their adsorption capacities. A critical analysis of the different mechanisms involved during the decolouration process and their application for dye removal has been discussed in detail in this up-to-date review. From a wide range of consulted literature review, it is evident that some clays have appreciable adsorption capacities on top of being widely available. It was also noted that several parameters like contact time, dosage, concentration, temperature and pH affect the removal of dyes. Furthermore, the application of clay minerals for decolourising water represents economic viable and locally available materials that can be used substantially for pollution control and management. Conclusions were also drawn and suggestions for future research perspectives are proposed. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. CASTOR OIL-BASED BUILDING MATERIALS REINFORCED WITH FLY ASH, CLAY, EXPANDED PERLITE AND PUMICE POWDER

    Directory of Open Access Journals (Sweden)

    Figen Balo

    2011-09-01

    Full Text Available This paper reports the results of a study conducted to evaluate the influence of class C fly ash (FA, clay (C, expanded perlite (EP, pumice powder (PP and epoxidized castor oil (ECO on the density, thermal conductivity, compressive strength, tensile strength, abrasion loss and water absorption of building material. Density, thermal conductivity, compressive strength and tensile strength decreased with the increase of ECO and FA as replacement for building material. These properties also decreased with increasing process temperature. The addition of clay in the building material had an increasing effect on these properties. The addition of clay decreased abrasion loss and water absorption as a function of replacement percent. The minimum thermal conductivity and maximum water absorption observed for the sample made with minimum clay and maximum FA-ECO ratios processed at the highest process temperature. The maximum compression-tensile strengths and minimum abrasion loss observed for the sample with maximum clay and minimum FA-ECO ratios processed at the lowest process temperature.

  1. Rheological behavior of clay-nanoparticle hybrid-added bentonite suspensions: specific role of hybrid additives on the gelation of clay-based fluids.

    Science.gov (United States)

    Jung, Youngsoo; Son, You-Hwan; Lee, Jung-Kun; Phuoc, Tran X; Soong, Yee; Chyu, Minking K

    2011-09-01

    Two different types of clay nanoparticle hybrid, iron oxide nanoparticle clay hybrid (ICH) and Al(2)O(3)-SiO(2) nanoparticle clay hybrid (ASCH), were synthesized and their effects on the rheological properties of aqueous bentonite fluids in steady state and dynamic state were explored. When ICH particles were added, bentonite particles in the fluid cross-link to form relatively well-oriented porous structure. This is attributed to the development of positively charged edge surfaces in ICH that leads to strengthening of the gel structure of the bentonite susensions. The role of ASCH particles on the interparticle association of the bentonite fluids is different from that of ICH and sensitive to pH. As pH of ASCH-added bentonite suspensions increased, the viscosity, yield stress, storage modulus, and flow stress decreased. In contrast, at low pH, the clay suspensions containing ASCH additives were coagulated and their rheological properties become close to those of ICH added bentonite fluids. A correlation between the net surface charge of the hybrid additives and the rheological properties of the fluids indicates that the embedded nanoparticles within the interlayer space control the variable charge of the edge surfaces of the platelets and determine the particles association behavior of the clay fluids.

  2. Radiation-induced synthesis of vinyl copolymer based nanocomposites filled with reactive organic montmorillonite clay

    Science.gov (United States)

    Kim, Sang-Kyum; Kwen, Hai-Doo; Choi, Seong-Ho

    2012-05-01

    Vinyl copolymer-clay nanocomposites were prepared by γ-irradiation-initiated radical polymerization using a mixture of styrene (St) and divinyl benzene (DVB) in the presence of reactive organic montmorillonite clay (OMMT) in methanol at room temperature. Reactive OMMT was synthesized by a cation exchange reaction of Na+-MMT and 1-[(4-ethylphenyl)methyl]-3-butyl-imidazolium chloride as a reactive organic modifier in an aqueous solution. The microstructures of the nanocomposites were confirmed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The thermal stability was examined by thermo gravimetric analysis (TGA). As a result, the reactive OMMT was a good additive material for preparing vinyl copolymer-clay nanocomposites.

  3. New magnetic organic-inorganic composites based on hydrotalcite-like anionic clays for drug delivery

    Energy Technology Data Exchange (ETDEWEB)

    Carja, Gabriela [Department of Physical Chemistry, Faculty of Industrial Chemistry, Technical University of Iasi, 71 Mangeron Boulevard, 700050 Iasi (Romania); Chiriac, Horia [National Institute of Research and Development for Technical Physics, 47 Mangeron Boulevard, 700050 Iasi (Romania)]. E-mail: hchiriac@phys-iasi.ro; Lupu, Nicoleta [National Institute of Research and Development for Technical Physics, 47 Mangeron Boulevard, 700050 Iasi (Romania)

    2007-04-15

    The structural 'memory effect' of anionic clays was used to obtain layered double hydroxides (LDHs) with tailored magnetic properties, by loading iron oxides and/or spinel structures on iron partially substituted hydrotalcite-like materials. The obtained magnetic layered structures were further used as precursors for new hybrid nanostructures, such as aspirin-hydrotalcite-like anionic clays. Transmission electron microscopy (TEM) analysis shows that small iron oxide or spinel nanoparticles coexist with the fibrous drug particles on the surface of partially aggregated typical clay-like particles. The specific saturation magnetization of the loaded LDHs can be increased up to 70 emu/g by using specific post-synthesis treatments.

  4. Modeling of adsorption of toxic chromium on natural and surface modified lightweight expanded clay aggregate (LECA)

    Energy Technology Data Exchange (ETDEWEB)

    Kalhori, Ebrahim Mohammadi, E-mail: zarrabi62@yahoo.com [Department of Environmental Health Engineering, Faculty of Health, Alborz University of Medical Sciences, P.O. Box No: 31485/561, Alborz, Karaj (Iran, Islamic Republic of); Yetilmezsoy, Kaan, E-mail: yetilmez@yildiz.edu.tr [Department of Environmental Engineering, Faculty of Civil Engineering, Yildiz Technical University, 34220 Davutpasa, Esenler, Istanbul (Turkey); Uygur, Nihan, E-mail: uygur.n@gmail.com [Department of Environmental Engineering, Faculty of Engineering, Adiyaman University, 02040 Altinsehir, Adiyaman (Turkey); Zarrabi, Mansur, E-mail: mansor62@gmail.com [Department of Environmental Health Engineering, Faculty of Health, Alborz University of Medical Sciences, P.O. Box No: 31485/561, Alborz, Karaj (Iran, Islamic Republic of); Shmeis, Reham M. Abu, E-mail: r.abushmeis@yahoo.com [Department of Basic Pharmaceutical Sciences, Faculty of Pharmacy, Isra University, PO Box 140753, code 11814, Amman (Jordan)

    2013-12-15

    Lightweight Expanded Clay Aggregate (LECA) modified with an aqueous solution of magnesium chloride MgCl{sub 2} and hydrogen peroxide H{sub 2}O{sub 2} was used to remove Cr(VI) from aqueous solutions. The adsorption properties of the used adsorbents were investigated through batch studies, Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), X-ray Fluorescence Spectroscopy (XRF), and Fourier Transform Infrared (FTIR) spectroscopy. The effect created by magnesium chloride on the modification of the LECA surface was greater than that of hydrogen peroxide solution and showed a substantial increase in the specific surface area which has a value of 76.12 m{sup 2}/g for magnesium chloride modified LECA while the values of 53.72 m{sup 2}/g, and 11.53 m{sup 2}/g were found for hydrogen peroxide modified LECA and natural LECA, respectively. The extent of surface modification with enhanced porosity in modified LECA was apparent from the recorded SEM patterns. XRD and FTIR studies of themodified LECA surface did not show any structural distortion. The adsorption kinetics was found to follow the modified Freundlich kinetic model and the equilibrium data fitted the Sips and Dubinin-Radushkevich equations better than other models. Maximum sorption capacities were found to be 198.39, 218.29 and 236.24 mg/g for natural LECA, surface modified LECA with H{sub 2}O{sub 2} and surface modified LECA with MgCl{sub 2}, respectively. Adsorbents were found to have only a weak effect on conductivity and turbidity of aqueous solutions. Spent natural and surface modified LECA with MgCl{sub 2} was best regenerated with HCl solution, while LECA surface modified with H{sub 2}O{sub 2} was best regenerated with HNO{sub 3} concentrated solution. Thermal method showed a lower regeneration percentage for all spent adsorbents.

  5. Mechanism of Exfoliation and Prediction of Materials Properties of Clay-Polymer Nanocomposites from Multiscale Modeling.

    Science.gov (United States)

    Suter, James L; Groen, Derek; Coveney, Peter V

    2015-12-09

    We describe the mechanism that leads to full exfoliation and dispersion of organophilic clays when mixed with molten hydrophilic polymers. This process is of fundamental importance for the production of clay-polymer nanocomposites with enhanced materials properties. The chemically specific nature of our multiscale approach allows us to probe how chemistry, in combination with processing conditions, produces such materials properties at the mesoscale and beyond. In general agreement with experimental observations, we find that a higher grafting density of charged quaternary ammonium surfactant ions promotes exfoliation, by a mechanism whereby the clay sheets slide transversally over one another. We can determine the elastic properties of these nanocomposites; exfoliated and partially exfoliated morphologies lead to substantial enhancement of the Young's modulus, as found experimentally.

  6. A MODIFIED CAM CLAY MODEL FOR STRUCTURED SOFT CALYS%结构性软黏土的修正剑桥模型

    Institute of Scientific and Technical Information of China (English)

    殷杰

    2013-01-01

    Natural soft clays are generally subject to the effects of a soil structure. How to reflect the effects in the corresponding constitutive model is an important issue. Based on the modified cam clay model, a parameter designated as structure yield stress was introduced to describe the shape of an initial yield surface due to the soil structure, and an anisotropic parameter was presented to characterize the rotation of a yield surface due to initial anisotropy. According to the mechanism of abrupt loss of a soil structure for natural clays, the elastic stress strain relationship was applied in the pre-yield state, and corresponding hardening law and associated flow rule consistent with a modified cam-clay model were adopted since the resistance of a soil structure in the post-yield state is completely exhausted. According to the condition of consistency, the incremental stress-strain relationship was established and a modified Cam Clay model for structured soft clays was developed. Significant improvements were demonstrated in the performance of the new model by comparing with experimental data in the stress path tests for Bothkennar soft clay.%天然软黏土普遍受到土结构性的影响,如何在土体本构模型中反映这一影响显得非常重要.该文从修正剑桥模型出发,引入结构屈服应力参数表征受土结构性影响的天然土初始屈服面的形状;引入各向异性参数描述天然土体初始各向异性引起的屈服面旋转.基于土结构性突变屈服破坏机理,屈服前结构性软黏土呈现弹性的力学性质,屈服后土结构性的影响完全丧失,采用同修正剑桥模型一致的硬化规律和流动法则.根据一致性连续条件,推导增量型的应力-应变关系,建立适用于结构性软黏土的弹塑性本构模型.选取国外已有的天然沉积Bothkennar软黏土,对比典型应力路径下的试验实测结果与模型计算结果,显示了该文模型模拟结构性软黏土受力变形特性的优越性.

  7. Using mixture design of experiments to assess the environmental impact of clay-based structural ceramics containing foundry wastes.

    Science.gov (United States)

    Coronado, M; Segadães, A M; Andrés, A

    2015-12-15

    This work describes the leaching behavior of potentially hazardous metals from three different clay-based industrial ceramic products (wall bricks, roof tiles, and face bricks) containing foundry sand dust and Waelz slag as alternative raw materials. For each product, ten mixtures were defined by mixture design of experiments and the leaching of As, Ba, Cd, Cr, Cu, Mo, Ni, Pb, and Zn was evaluated in pressed specimens fired simulating the three industrial ceramic processes. The results showed that, despite the chemical, mineralogical and processing differences, only chrome and molybdenum were not fully immobilized during ceramic processing. Their leaching was modeled as polynomial equations, functions of the raw materials contents, and plotted as response surfaces. This brought to evidence that Cr and Mo leaching from the fired products is not only dependent on the corresponding contents and the basicity of the initial mixtures, but is also clearly related with the mineralogical composition of the fired products, namely the amount of the glassy phase, which depends on both the major oxides contents and the firing temperature.

  8. One-Dimensional Simulation of Clay Drying

    Directory of Open Access Journals (Sweden)

    Siljan Siljan

    2002-04-01

    Full Text Available Drying of clay is simulated by a one-dimensional model. The background of the work is to form a better basis for investigation of the drying process in production of clay-based building materials. A model of one-dimensional heat and mass transfer in porous material is used and modified to simulate drying of clay particles. The convective terms are discretized by first-order upwinding, and the diffusive terms are discretized by central differencing. DASSL was used to solve the set of algebraic and differential equations. The different simulations show the effect of permeability, initial moisture content and different boundary conditions. Both drying of a flat plate and a spherical particle are modelled.

  9. Constructing wetlands: measuring and modeling feedbacks of oxidation processes between plants and clay-rich material

    Science.gov (United States)

    Saaltink, Rémon; Dekker, Stefan C.; Griffioen, Jasper; Wassen, Martin J.

    2016-04-01

    Interest is growing in using soft sediment as a building material in eco-engineering projects. Wetland construction in the Dutch lake Markermeer is an example: here the option of dredging some of the clay-rich lake-bed sediment and using it to construct 10.000 ha of wetland will soon go under construction. Natural processes will be utilized during and after construction to accelerate ecosystem development. Knowing that plants can eco-engineer their environment via positive or negative biogeochemical plant-soil feedbacks, we conducted a six-month greenhouse experiment to identify the key biogeochemical processes in the mud when Phragmites australis is used as an eco-engineering species. We applied inverse biogeochemical modeling to link observed changes in pore water composition to biogeochemical processes. Two months after transplantation we observed reduced plant growth and shriveling as well as yellowing of foliage. The N:P ratios of plant tissue were low and were affected not by hampered uptake of N but by enhanced uptake of P. Plant analyses revealed high Fe concentrations in the leaves and roots. Sulfate concentrations rose drastically in our experiment due to pyrite oxidation; as reduction of sulfate will decouple Fe-P in reducing conditions, we argue that plant-induced iron toxicity hampered plant growth, forming a negative feedback loop, while simultaneously there was a positive feedback loop, as iron toxicity promotes P mobilization as a result of reduced conditions through root death, thereby stimulating plant growth and regeneration. Given these two feedback mechanisms, we propose that when building wetlands from these mud deposits Fe-tolerant species are used rather than species that thrive in N-limited conditions. The results presented in this study demonstrate the importance of studying the biogeochemical properties of the building material and the feedback mechanisms between plant and soil prior to finalizing the design of the eco-engineering project.

  10. Studying the degradation of polyhydroxybutyrate-co-valerate during processing with clay-based nanofillers

    DEFF Research Database (Denmark)

    Cabedo, Luis; Plackett, David; Gimenez, Enrique

    2009-01-01

    Polyhydroxybutyrate-co-valerate (PHBV) is attracting interest as a new material for packaging applications and nanoparticulate layered silicates are being increasingly explored as a way to improve PHBV film properties. In this context, it is essential to understand how different types of nanofill......Polyhydroxybutyrate-co-valerate (PHBV) is attracting interest as a new material for packaging applications and nanoparticulate layered silicates are being increasingly explored as a way to improve PHBV film properties. In this context, it is essential to understand how different types...... of nanofillers could influence polymer properties. PHBV was processed with three-layered clay types using different mixing methods, and we examined the effect of processing time, clay type, and clay content on polymer molecular weight and composite morphology. PHBV molecular weight (Mw) decreased by 38% after...... extrusion processing and was further reduced in the presence of montmorillonite (MMT). However, when PHBV was processed with kaolinite as the additive, no further reduction in polymer molecular weight was observed. Molecular weight also decreased as the MMT clay content increased from 1 to 5 wt...

  11. Factors affecting the hydraulic performance of infiltration based SUDS in clay

    DEFF Research Database (Denmark)

    Bockhorn, B.; Klint, K.E.S.; Locatelli, Luca;

    2017-01-01

    with hydraulic properties ranging from sand to clay showed that infiltration capacities vary greatly for the different soil types observed in glacial till. The inclusion of heterogeneities dramatically increased infiltration volume by a factor of 22 for a soil with structural changes above and below the CaC03...

  12. Screening of heavy metal containing waste types for use as raw material in Arctic clay-based bricks

    DEFF Research Database (Denmark)

    Belmonte, Louise Josefine; Ottosen, Lisbeth M.; Kirkelund, Gunvor Marie

    2016-01-01

    In the vulnerable Arctic environment, the impact of especially hazardous wastes can have severe consequences and the reduction and safe handling of these waste types are therefore an important issue. In this study, two groups of heavy metal containing particulate waste materials, municipal solid...... waste incineration (MSWI) fly and bottom ashes and mine tailings (i.e., residues from the mineral resource industry) from Greenland were screened in order to determine their suitability as secondary resources in clay-based brick production. Small clay discs, containing 20 or 40% of the different...... particulate waste materials, were fired and material properties and heavy metal leaching tests were conducted before and after firing. Remediation techniques (washing in distilled water and electrodialytical treatment) applied to the fly ash reduced leaching before firing. The mine tailings and bottom ash...

  13. Poly(N-isopropylacrylamide)-clay based hydrogels controlled by the initiating conditions: evolution of structure and gel formation.

    Science.gov (United States)

    Strachota, Beata; Matějka, Libor; Zhigunov, Alexander; Konefał, Rafał; Spěváček, Jiří; Dybal, Jiří; Puffr, Rudolf

    2015-12-28

    The formation of the hydrogel poly(N-isopropylacrylamide)-clay (LAPONITE®) by redox polymerization was investigated, and the main factors governing the gel build-up were determined. The significant effect of the redox initiating system ammonium peroxodisulfate (APS) and tetramethylethylenediamine (TEMED) on gel formation and structure was established, making it possible to control the structure of the gel. Moreover, the pre-reaction stage involving the quality of the clay exfoliation in an aqueous suspension and the interaction of reaction components with the clay play a role in controlling the polymerization and gel structure. The molecular and phase structure evolution during polymerization was followed in situ by the following independent techniques: Fourier transform infrared spectroscopy (FTIR), chemorheology, small-angle X-ray scattering (SAXS) and ultraviolet-visible spectroscopy (UV/Vis). The combination of these methods enabled us to describe in detail particular progress stages during the gel formation and determine the correlation of the corresponding processes on a time and conversion scale. The mechanism of gel formation was refined based on these experimental results.

  14. Steady state theoretical model of fired clay hollow bricks for enhanced external wall thermal insulation

    Energy Technology Data Exchange (ETDEWEB)

    Bouchair, Ammar [Laboratoire de Recherche Cadre Bati et Environnement, Departement d' Architecture, Faculte des Sciences de l' Ingenieur, Universite de Jijel, BP 98 Ouled Aissa, Jijel 18000 (Algeria)

    2008-10-15

    This paper proposes a theoretical model to study the steady state thermal behavior of fired clay hollow bricks for enhanced external wall thermal insulation. The study aims at the development of new materials and structural components with good thermal material properties, with respect to energy saving and ecological design. Thermal insulation capacity of two external walls of different thicknesses, constructed of locally produced bricks, is studied. The basic brick units used for the investigation are small-size bricks with eight equal cavities or recesses and big-size bricks with twelve equal recesses. Their recesses configuration has been varied to perform the assessment. The insulation materials injected within brick recesses during the assessment are granulated cork and expanded polystyrene. The improvement in the thermal performance of the walls will be the result of optimization among the various factors such as brick cavity configurations, integration of insulation within brick recesses and the cavity surface emissivities. So emphasis is given to the study of the impact of these factors singly or in combination on the overall thermal resistance of walls in order to find out the best design solutions to maximize their thermal insulation capacity. Computer modeling and calculations performed, for steady state conditions, show that the increase in hollow brick cavity height contributes to the improvement of the overall thermal resistance of the order of 18-20%. The improvement could significantly increase to the range of 88.64% and 93.33%, if the bricks used are injected with the insulating material. If the cavity surface emissivities are lowered to 0.3, the improvement will be 72.73-78.33%. The results have also shown that replacing the cork by expanded polystyrene (EPS), having lower thermal conductivity, would not improve significantly the overall thermal resistance. This improvement is 9.08% for a wall of small-size bricks having configuration BS2CV and 8

  15. Outbursts of wet clays and the method of fighting them

    Energy Technology Data Exchange (ETDEWEB)

    Kesseru, Z.

    1986-01-01

    Under given stress conditions the fractured clay-bearing rocks may produce sudden rock displacements. The survey of experiences and the tests conducted concerning these types of water-rock interaction called wet clay outbursts are dealt with. A mechanical model developed for representing such phenomena as well as the laboratory tests preceding the model studies are described. Based on case studies the method of predetection and the choice of suitable methods of prevention are discussed.

  16. Semi-industrial production of organo clays to use in base oil drilling fluid; Producao em escala piloto de argilas organofilicas visando uso em fluidos de perfuracao base oleo

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Heber S.; Martins, Alice B.; Costa, Danubia L. da; Ferreira, Heber C.; Neves, Gelmires de A.; Melo, Tomas J.A. de [Universidade Federal de Campina Grande (UFCG), PB (Brazil); Teixeira Neto, Erico [Universidade Federal do ABC (UFABC), Santo Andre, SP (Brazil)

    2008-07-01

    The drilling fluids are essential to the operations of exploration of oil. The organoclays are widely used in the composition of the oil based drilling fluids and raw materials are of high value added. These clays can be obtained, traditionally, from bentonitic clay treated, in water, with ionic surfactants, however, non-ionic surfactants can be adsorbed on the surface of interlamelar bentonitic clay, naturally hydrophilic, making them organophilic. A pilot plant for production of organoclays was mounted in the Recycling Laboratory / UFCG. The bentonitic clay imported Cloisite Na{sup +R} was treated with a non-ionic surfactant in levels of 40, 50 and 60% in scale and bench-scale pilot. The commercial organoclay VG-69{sup R} was used as a standard for comparison of results. The clay obtained were characterized by X-ray diffraction, and Foster's swelling. The oil based fluids were prepared in accordance with the standards of PETROBRAS (N-22581 1997 and N-2259, 1997). Tests show that the characterization of organoclays have obtained intercalation of non-ionic surfactant with great expansion of layers of clay, with interlayer distances more significant than the clay trade, both on clay obtained in the laboratory scale as in clays obtained by pilot scale, with results very similar for both methods. It appears that it is possible the pilot-scale production of organoclays with equivalent quality produced in the laboratory scale and quality compatible with the clay used commercially. (author)

  17. Swelling compositions based polycarboxylic acids and bentonite clays in solutions of salts of metals

    Directory of Open Access Journals (Sweden)

    A. Sarshesheva

    2012-12-01

    Full Text Available This work is devoted to the synthesis of chemical cross-linked composite materials made of natural inorganic polymer bentonite clay of Manrak deposit, and polyacrylic and polymethacrylic acids. The swelling ability of the composition in solutions of salts of heavy metals (Ni2+ and Pb2+, influence of solution of concentration, pH and temperature on the swelling ability is investigated.

  18. Modelling tools for assessing bioremediation performance and risk of chlorinated solvents in clay tills

    DEFF Research Database (Denmark)

    Chambon, Julie Claire Claudia

    transfer limitations in order to achieve remediation in reasonable timeframes. The importance of mass transfer limitations depends on the extent of the reductive dechlorination in the matrix (termed bioactive zones), and the spacing between them, which is controlled by the injection interval. Numerical......Chlorinated solvents are widespread contaminants in the subsurface. In lowpermeability fractured media, such as clay tills, chlorinated solvents are transported downwards along preferential pathways, formed by fractures and sand lenses, and diffuse into the adjacent clay matrix. These contaminants...... are trapped in the low-permeability matrix and can then slowly back diffuse to the fracture network, forming a long-term secondary contamination source to the underlying aquifers. Because of the complex transport and degradation processes and the mass transfer limitations, risk assessment and remediation...

  19. Influence of clay particles on microfluidic-based preparation of hydrogel composite microsphere

    Science.gov (United States)

    Hong, Joung Sook

    2016-05-01

    For the successful fabrication of a hydrogel composite microsphere, this study aimed to investigate the influence of clay particles on microsphere formation in a microfluidic device which has flow focusing and a 4.5:1 contraction channel. A poly alginic acid solution (2.0 wt.%) with clay particles was used as the dispersed phase to generate drops in an oil medium, which then merged with drops of a CaCl2 solution for gelation. Drop generations were observed with different flow rates and particles types. When the flow rate increased, drop generation was enhanced and drop size decreased by the build-up of more favorable hydrodynamic flow conditions to detach the droplets. The addition of a small amount of particles insignificantly changed the drop generation behavior even though it reduced interfacial tension and increased the viscosity of the solution. Instead, clays particles significantly affected hydro-gelation depending on the hydrophobicity of particles, which produced further heterogeneity in the shape and size of microsphere.

  20. Dynamic Strength and Accumulated Plastic Strain Development Laws and Models of the Remolded Red Clay under Long-Term Cyclic Loads: Laboratory Test Results

    Directory of Open Access Journals (Sweden)

    Li Jian

    2015-09-01

    Full Text Available The dynamic strength and accumulated plastic strain are two important parameters for evaluating the dynamic response of soil. As a special clay, the remolded red clay is often used as the high speed railway subgrade filling, but studies on its dynamic characteristics are few. For a thorough analysis of the suitability of the remolded red clay as the subgrade filling, a series of long-term cyclic load triaxial test under different load histories are carried out. Considering the influence of compactness, confining pressure, consolidation ratio, vibration frequency and dynamic load to the remolded red clay dynamic property, the tests obtain the development curves of the dynamic strength and accumulated plastic strain under different test conditions. Then, through curve fitting method, two different hyperbolic models respectively for the dynamic strength and accumulated plastic strain are built, which can match the test datum well. By applying the dynamic strength model, the critical dynamic strength of the remolded red clay are gained. Meanwhile, for providing basic datum and reference for relevant projects, all key parameters for the dynamic strength and accumulated plastic strain of the remolded red clay are given in the paper.

  1. National Map Data Base On Landslide Prerequisites In Clay and Silt Areas - Development of Prototype

    Science.gov (United States)

    Viberg, Leif

    Swedish geotechnical institute, SGI, has in co-operation with Swedish geologic survey, Lantmateriet (land surveying) and Swedish Rescue Service developed a theme database on landslide prerequisites in clay and silt areas. The work is carried out on commission of the Swedish government. A report with suggestions for production of the database has been delivered to the government. The database is a prototype, which has been tested in an area in northern Sweden. Recommended presentation map scale is about 1:50 000. Distribution of the database via Internet is discussed. The aim of the database is to use it as a modern planning tool in combination with other databases, e g databases on flooding prognoses. The main use is supposed to be in early planning stages, e g for new building and infrastructure development and for risk analyses. The database can also be used in more acute cases, e g for risk analyses and rescue operations in connection with flooding over large areas. Users are supposed to be municipal and county planners and rescue services, infrastructure planners, consultants and assurance companies. The database is constructed by combination of two existing databases: Elevation data and soil map data. The investigation area is divided into three zones with different stability criteria: 1. Clay and silt in sloping ground or adjoining water. 2. Clay and silt in flat ground. 3. Rock and other soils than clay and silt. The geometrical and soil criteria for the zones are specified in an algoritm, that will do the job to sort out the different zones. The algoritm is thereby using data from the elevation and soil databases. The investigation area is divided into cells (raster format) with 5 x 5 m side length. Different algoritms had to be developed before reasonable calculation time was reached. The theme may be presented on screen or as a map plot. A prototype map has been produced for the test area. A description is accompanying the map. The database is suggested

  2. Segmental motions of poly(ethylene glycol) chains adsorbed on Laponite platelets in clay-based hydrogels: a NMR investigation.

    Science.gov (United States)

    Lorthioir, Cédric; Khalil, Mouhamad; Wintgens, Véronique; Amiel, Catherine

    2012-05-22

    The segmental dynamics of poly(ethylene glycol) (PEG) chains adsorbed on the clay platelets within nanocomposite PEG/Laponite hydrogels was investigated over the tens of microseconds time scale, using combined solution and solid-state NMR approaches. In a first step, the time evolution of the molecular mobility displayed by the PEG chains following the addition to a Laponite aqueous dispersion was monitored during the aggregation of the clay disks and the hydrogel formation, by means of (1)H solution-state NMR. Part of the PEG repeat units were found to get strongly constrained during the gelation process. Comparisons between this time evolution of the PEG local dynamics in the PEG/Laponite/water systems and the increase of the macroscopic storage shear modulus, mainly governed by the assembling of the Laponite disks, indicate that the slowing down of the segmental motions arises from adsorbed PEG repeat units or chain portions strongly constrained between aggregated clay layers. In a second step, after completion of the gelation process, the molecular motions of the adsorbed PEG chains were probed by (1)H solid-state NMR spectroscopy. (1)H double-quantum experiments indicate that the adsorbed PEG repeat units, though reported to be frozen over a few tens of nanoseconds, still display significant reorientational motions over the tens of microseconds time scale. Using a comparison with a model system of amorphized PEG chains, the characteristic frequency of these segmental motions was found to range between 78.0 kHz and 100.7 MHz at 300 K. Interestingly, at this temperature, the level of reorientational motions detected for these adsorbed PEG chain portions was found to be as restricted as the one of bulk amorphous PEG chains, cooled at a slightly lower temperature (about 290 K).

  3. Hypoplastic model for simulation of compressibility characteristics of cement-admixed Bangkok soft clay at high water content

    Science.gov (United States)

    Chattonjai, Piyachat

    2016-06-01

    The developed hypoplastic model for simulation of compressibility characteristics of cement-admixed Bangkok soft clay at high water content was proposed in this paper. By using unique equation, the model is able to predict the relationship between void ratio and vertical effective stress of different water and cement content of soil cement. For practically convenient utilization and understanding, the parameters of Q1 which represented to initial cement bonding of soil (the initial value of structure tensor at time = 0) and C2 which effected to the model stiffness on isotropic consolidation direction, at 45° for loading and 225° for unloading of stress response envelope, were proposed as the function of cement and water content by comparing with dry weight of soil. By numerical integration that satisfied one-dimensional settlement, the simulation results were directly compared with fifteen experimental results to verify the accuracy of the proposed model.

  4. A data analysis workflow to enhance clay and organic carbon models using proximal Vis-NIR data

    DEFF Research Database (Denmark)

    Tabatabai, Salman; Knadel, Maria; Greve, Mogens Humlekrog

    Modelling proximal sensors data is becoming a norm in soil characterization and mapping. In many cases, these models still have low predictive capabilities and lack robustness due to the large amount of noise from several environmental factors. In this study we proposed a combination of extensive...... data preprocessing (preprocessing survey) and two variable selection methods to significantly increase visible near-infrared spectroscopy (Vis-NIRS) model performance and stability. Spectra of eight agricultural fields were measured in the range of 350-2200 nm using a mobile sensor platform (Veris....... Spectral data were preprocessed using several thousands of combinations of methods/settings including Savistky-Golay smoothing/derivatives, multiplicative scatter correction, standard normal variate and generalized least squares weighting and the optimum Partial Least Squares (PLS) models for clay...

  5. Multi-scale modeling of the behaviour of water and ions clays; Modelisation multi-echelles du comportement de l'eau et des ions dans les argiles

    Energy Technology Data Exchange (ETDEWEB)

    Rotenberg, B

    2007-10-15

    Predicting the fate of radioactive waste stored in a clay formation requires a good understanding of the transport properties of water and ions in clays. Their diffusion in this charged porous medium is described by empirical parameters such as their partitioning coefficient Kd which accounts for the interactions with the mineral surfaces. The present work deals with the relevance of this concept and its definition based on microscopic grounds. We have first modeled the ionic contribution to the dielectric properties of clays and suggested an experimental determination of Kd from dielectric spectroscopy measurements. Using microscopic simulations (Monte-Carlo and Molecular Dynamics), we then have computed the Gibbs free energy and enthalpy for ionic exchange in the case of alkaline cations. They control the value of Kd and its evolution with the temperature. The results for cesium are in good agreement with both microcalorimetric measurements and the determination of Kd at different temperatures. We have participated in the development of a new lattice simulation method (Lattice Fokker-Planck), which we have then used to link explicitly the microscopic dynamics of ions to the diffusion-reaction model underlying the definition of Kd. Finally, we have used Molecular Dynamics to investigate the kinetics of exchange of water and ions between clay particles (interlayer) and the extra-particle porosity. The results confirm the generally admitted idea that water and ions can explore the whole porosity, whereas anions are excluded from the interlayers. (author)

  6. Hydrodynamic erosion process of undisturbed clay

    NARCIS (Netherlands)

    Zhao, G.; Visser, P.J.; Vrijling, J.K.

    2011-01-01

    This paper describes the hydrodynamic erosion process of undisturbed clay due to the turbulent flow, based on theoretical analysis and experimental results. The undisturbed clay has the unique and complicated characteristics of cohesive force among clay particles, which are highly different from dis

  7. Law of nonlinear flow in saturated clays and radial consolidation

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    It was derived that micro-scale amount level of average pore radius of clay changed from 0.01 to 0.1 micron by an equivalent concept of flow in porous media. There is good agreement between the derived results and test ones. Results of experiments show that flow in micro-scale pore of saturated clays follows law of nonlinear flow. Theoretical analyses demonstrate that an interaction of solid-liquid interfaces varies inversely with permeability or porous radius. The interaction is an important reason why nonlinear flow in saturated clays occurs. An exact mathematical model was presented for nonlinear flow in micro-scale pore of saturated clays. Dimension and physical meanings of parameters of it are definite. A new law of nonlinear flow in saturated clays was established. It can describe characteristics of flow curve of the whole process of the nonlinear flow from low hydraulic gradient to high one. Darcy law is a special case of the new law. A mathematical model was presented for consolidation of nonlinear flow in radius direction in saturated clays with constant rate based on the new law of nonlinear flow. Equations of average mass conservation and moving boundary, and formula of excess pore pressure distribution and average degree of consolidation for nonlinear flow in saturated clay were derived by using an idea of viscous boundary layer, a method of steady state in stead of transient state and a method of integral of an equation. Laws of excess pore pressure distribution and changes of average degree of consolidation with time were obtained. Results show that velocity of moving boundary decreases because of the nonlinear flow in saturated clay. The results can provide geology engineering and geotechnical engineering of saturated clay with new scientific bases. Calculations of average degree of consolidation of the Darcy flow are a special case of that of the nonlinear flow.

  8. 软土的循环累积变形模型研究%Cyclic accumulative deformation model of soft clay

    Institute of Scientific and Technical Information of China (English)

    赵春彦; 周顺华

    2011-01-01

    Based on the results of dynamic triaxial test on soft clay in Shanghai, the factors influencing accumulative deformation and its development law were analyzed. The concept of equivalent cyclic dynamic stress level was introduced. Then a model on accumulative deformation of soft clay was put forward when taking cyclic number of train loading, coupling effect of static deviator stress and dynamic deviator stress, consolidation ways into account. The model was verified by test results. Test coefficients in the model were gained under different testing conditions. The results show that this model reflects development law of accumulative deformation well under many kinds of influencing factors. This model is just applicable to normally consolidated soft clay on the condition that cyclic stress ratio is less than critical cyclic stress ratio. To improve calculating and predicting precision of the model, it is advised that loading and consolidating conditions, which are in accordance with actual field circumstances, should be applied in the laboratory test that is used to gain the test constant values of the model.%基于上海地区饱和软土的动三轴试验成果,通过对累积变形影响因素及累积变形发展规律的分析,引入等效循环动应力水平的概念,建立能综合考虑列车荷载循环次数、静偏应力和和动偏应力的耦合作用、固结方式等影响因素的软粘土循环累积变形模型.结合试验成果对模型进行验证,确定不同试验条件下模型中的试验系数.研究结果表明:此模型能够很好地反映多种因素对软土循环累积变形规律的影响;此模型仅适用于软土正常固结且循环应力比小于临界循环应力比的情况;为提高模型计算和预测的精度,用室内试验确定模型中的试验系数时,应采用与现场实际相符的加载和固结条件.

  9. 1st International Conference on Calcined Clays for Sustainable Concrete

    CERN Document Server

    Favier, Aurélie

    2015-01-01

    This volume focuses on research and practical issues linked to Calcined Clays for Sustainable Concrete. The main subjects are geology of clays, hydration and performance of blended systems with calcined clays, alkali activated binders, economic and environmental impacts of the use of calcined clays in cement based materials. Topics addressed in this book include the influence of processing on reactivity of calcined clays, influence of clay mineralogy on reactivity, geology of clay deposits, Portland-calcined clay systems, hydration, durability, performance, Portland-calcined clay-limestone systems, hydration, durability, performance, calcined clay-alkali systems, life cycle analysis, economics and environmental impact of use of calcined clays in cement and concrete, and field applications. This book compiles the different contributions of the 1st International Conference on Calcined Clays for Sustainable Concrete, which took place in Lausanne, Switzerland, June, 23-25, 2015.The papers present the latest  res...

  10. Long-term non-isothermal reactive transport model of compacted bentonite, concrete and corrosion products in a HLW repository in clay

    Science.gov (United States)

    Mon, Alba; Samper, Javier; Montenegro, Luis; Naves, Acacia; Fernández, Jesús

    2017-02-01

    Radioactive waste disposal in deep geological repositories envisages engineered barriers such as carbon-steel canisters, compacted bentonite and concrete liners. The stability and performance of the bentonite barrier could be affected by the corrosion products at the canister-bentonite interface and the hyper-alkaline conditions caused by the degradation of concrete at the bentonite-concrete interface. Additionally, the host clay formation could also be affected by the hyper-alkaline plume at the concrete-clay interface. Here we present a non-isothermal multicomponent reactive transport model of the long-term (1 Ma) interactions of the compacted bentonite with the corrosion products of a carbon-steel canister and the concrete liner of the engineered barrier of a high-level radioactive waste repository in clay. Model results show that magnetite is the main corrosion product. Its precipitation reduces significantly the porosity of the bentonite near the canister. The degradation of the concrete liner leads to the precipitation of secondary minerals and the reduction of the porosity of the bentonite and the clay formation at their interfaces with the concrete liner. The reduction of the porosity becomes especially relevant at t = 104 years. The zones affected by pore clogging at the canister-bentonite and concrete-clay interfaces at 1 Ma are approximately equal to 1 and 3.3 cm thick, respectively. The hyper-alkaline front (pH > 8.5) spreads 2.5 cm into the clay formation after 1 Ma. Our simulation results share the key features of the models reported by others for engineered barrier systems at similar chemical conditions, including: 1) Pore clogging at the canister-bentonite and concrete-clay interfaces; 2) Narrow alteration zones; and 3) Limited smectite dissolution after 1 Ma.

  11. Long-term non-isothermal reactive transport model of compacted bentonite, concrete and corrosion products in a HLW repository in clay.

    Science.gov (United States)

    Mon, Alba; Samper, Javier; Montenegro, Luis; Naves, Acacia; Fernández, Jesús

    2017-02-01

    Radioactive waste disposal in deep geological repositories envisages engineered barriers such as carbon-steel canisters, compacted bentonite and concrete liners. The stability and performance of the bentonite barrier could be affected by the corrosion products at the canister-bentonite interface and the hyper-alkaline conditions caused by the degradation of concrete at the bentonite-concrete interface. Additionally, the host clay formation could also be affected by the hyper-alkaline plume at the concrete-clay interface. Here we present a non-isothermal multicomponent reactive transport model of the long-term (1Ma) interactions of the compacted bentonite with the corrosion products of a carbon-steel canister and the concrete liner of the engineered barrier of a high-level radioactive waste repository in clay. Model results show that magnetite is the main corrosion product. Its precipitation reduces significantly the porosity of the bentonite near the canister. The degradation of the concrete liner leads to the precipitation of secondary minerals and the reduction of the porosity of the bentonite and the clay formation at their interfaces with the concrete liner. The reduction of the porosity becomes especially relevant at t=10(4)years. The zones affected by pore clogging at the canister-bentonite and concrete-clay interfaces at 1Ma are approximately equal to 1 and 3.3cm thick, respectively. The hyper-alkaline front (pH>8.5) spreads 2.5cm into the clay formation after 1Ma. Our simulation results share the key features of the models reported by others for engineered barrier systems at similar chemical conditions, including: 1) Pore clogging at the canister-bentonite and concrete-clay interfaces; 2) Narrow alteration zones; and 3) Limited smectite dissolution after 1Ma.

  12. High temperature proton exchange membranes based on polybenzimidazole and clay composites for fuel cells

    DEFF Research Database (Denmark)

    Plackett, David; Siu, Ana; Li, Qingfeng

    2011-01-01

    and pyridinium salts with varying polarity and hydrogen-bonding capacity. Clay modification by ion-exchange reactions involving replacement of interlayer inorganic cations was confirmed using X-ray photoelectron and infrared spectroscopy techniques. The cast PBI membranes were characterized by their water uptake......, acid doping and swelling, tensile strength, conductivity and hydrogen permeability as well as by fuel cell tests. For the composite membranes, high acid doping levels were achieved with sufficient mechanical strength and improved dimensional stability or reduced membrane swelling. At an acid doping......-doped pristine PBI membranes. In accordance with the hydrogen permeability measurements, fuel cell tests exhibited high open circuit voltages (i.e., 1.02 V) at room temperature as well as high I–V performance compared with normal PBI membranes....

  13. Prediction of Settlements of Soft Clay Subjected to Long-Term Dynamic Load

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    -Presented is the numerical analysis of settlements of soft soil by a 2-D dynamic effective stress FEM method. The model based on the results of cyclic triaxial tests on the reconstituted soft Ariake clay is used to predict the wave induced excess pore water pressure and residual strain of soft clay. The settlements of two types of breakwaters on the soft clay under ocean wave load, a low embankment subjected to traffic load and the tunnel surrounded by soft clay in Shanghai subjected to locomotive load are calculated as examples.

  14. Removal of waterborne microorganisms by filtration using clay-polymer complexes.

    Science.gov (United States)

    Undabeytia, Tomas; Posada, Rosa; Nir, Shlomo; Galindo, Irene; Laiz, Leonila; Saiz-Jimenez, Cesareo; Morillo, Esmeralda

    2014-08-30

    Clay-polymer composites were designed for use in filtration processes for disinfection during the course of water purification. The composites were formed by sorption of polymers based on starch modified with quaternary ammonium ethers onto the negatively charged clay mineral bentonite. The performance of the clay-polymer complexes in removal of bacteria was strongly dependent on the conformation adopted by the polycation on the clay surface, the charge density of the polycation itself and the ratio between the concentrations of clay and polymer used during the sorption process. The antimicrobial effect exerted by the clay-polymer system was due to the cationic monomers adsorbed on the clay surface, which resulted in a positive surface potential of the complexes and charge reversal. Clay-polymer complexes were more toxic to bacteria than the polymers alone. Filtration employing our optimal clay-polymer composite yielded 100% removal of bacteria after the passage of 3L, whereas an equivalent filter with granular activated carbon (GAC) hardly yielded removal of bacteria after 0.5L. Regeneration of clay-polymer complexes saturated with bacteria was demonstrated. Modeling of the filtration processes permitted to optimize the design of filters and estimation of experimental conditions for purifying large water volumes in short periods.

  15. Direct Electron Transfer of Glucose Oxidase and Glucose Biosensor Based on Nano-structural Attapulgite Clay Matrix

    Institute of Scientific and Technical Information of China (English)

    XU, Jiming; HAN, Wenxia; YIN, Qifan; SONG, Jie; ZHONG, Hui

    2009-01-01

    The direct electrochemistry of glucose oxidase (GOD) was achieved based on the immobilization of GOD on a natural nano-structural attapulgite (ATP) clay film modified glassy carbon (GC) electrode. The immobilized GOD displayed a pair of well-defined quasi-reversible redox peaks with a formal potential (E~0) of -457.5 mV (vs. SCE) in 0.1 mol·L~(-1) pH 7.0 phosphate buffer solution. The peak current was linearly dependent on the scan rate, indicating that the direct electrochemistry of GOD in that case was a surface-controlled process. The immobilized glucose oxidase could retain bioactivity and catalyze the oxidation of glucose in the presence of ferrocene monocarboxylic acid (FMCA) as a mediator with the apparent Michaclis-Menten constant K_m~(app) of 1.16 mmol·L~(-1) The electrocatalytic response showed a linear dependence on the glucose concentration ranging widely from 5.0×10~(-6) to 6.05×10~(-4) mol·L~(-1) (with correlation coefficient of 0.9960). This work demonstrated that the nano-structural attapulgite clay was a good candidate material for the direct electrochemistry of the redox-active enzyme and the construction of the related enzyme biosensors. The proposed biosensors were applied to determine the glucose in blood and urine samples with satisfactory results.

  16. Screening of heavy metal containing waste types for use as raw material in Arctic clay-based bricks.

    Science.gov (United States)

    Belmonte, Louise Josefine; Ottosen, Lisbeth M; Kirkelund, Gunvor Marie; Jensen, Pernille Erland; Vestbø, Andreas Peter

    2016-11-10

    In the vulnerable Arctic environment, the impact of especially hazardous wastes can have severe consequences and the reduction and safe handling of these waste types are therefore an important issue. In this study, two groups of heavy metal containing particulate waste materials, municipal solid waste incineration (MSWI) fly and bottom ashes and mine tailings (i.e., residues from the mineral resource industry) from Greenland were screened in order to determine their suitability as secondary resources in clay-based brick production. Small clay discs, containing 20 or 40% of the different particulate waste materials, were fired and material properties and heavy metal leaching tests were conducted before and after firing. Remediation techniques (washing in distilled water and electrodialytical treatment) applied to the fly ash reduced leaching before firing. The mine tailings and bottom ash brick discs obtained satisfactory densities (1669-2007 kg/m(3)) and open porosities (27.9-39.9%). In contrast, the fly ash brick discs had low densities (1313-1578 kg/m(3)) and high open porosities (42.1-51. %). However, leaching tests on crushed brick discs revealed that heavy metals generally became more available after firing for all the investigated materials and that further optimisation is therefore necessary prior to incorporation in bricks.

  17. 饱和软粘土的不排水动力本构模型%Dynamic Constitutive Model of Saturated Clay under Undrained Condition

    Institute of Scientific and Technical Information of China (English)

    熊玉春; 房营光

    2007-01-01

    Based on the isotropic elastoplastic damage and multi-surface models, a new elastoplastic dynamic model for saturated clay under cyclic loading is proposed which can consider not only isotropic hardening and kinematic hardening but also isotropic shear damage and compression damage. The damage process is described respectively by shear damage variable and compression damage variable and further the damage evolution equations are developed, based on the accumulated plastic deviatoric strain. Numerical simulation of the saturated-clay subsoil subjected to input seismic acceleration shows that new model can preferably depict the dynamic response and then accumulated plastic deviatoric deformation.%根据动荷载作用下饱和软粘土的各向同性弹塑性损伤理论与多曲屈服面模型,提出了一个能分别考虑各向同性硬化、运动硬化以及压缩和剪切损伤的动力损伤本构模型.将压缩和剪切损伤变量表示为累积塑性偏应变路径长度的函数并基于该损伤变量来建立损伤演化方程.分别考虑压缩损伤和剪切损伤能够反映不排水循环加载条件下软粘土动泊松比的变化过程.最后,将模型引入饱和软粘土地基在不排水条件下的地震反应分析中,以验证模型的有效性.结果表明,模型能合理地描述饱和软粘土地基的动力响应及震陷变形.

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

    Science.gov (United States)

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

    2016-10-01

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

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

    Science.gov (United States)

    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.

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

    Institute of Scientific and Technical Information of China (English)

    曹会; 邢立新; 潘军; 刘立文; 杨东旭; 王莹

    2013-01-01

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

  1. CLAY AND CLAY-SUPPORTED REAGENTS IN ORGANIC SYNTHESES

    Science.gov (United States)

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

  2. Modeling of Coupled Thermo-Hydro-Mechanical-Chemical Processes for Bentonite in a Clay-rock Repository for Heat-generating Nuclear Waste

    Science.gov (United States)

    Xu, H.; Rutqvist, J.; Zheng, L.; Birkholzer, J. T.

    2016-12-01

    Engineered Barrier Systems (EBS) that include a bentonite-based buffer are designed to isolate the high-level radioactive waste emplaced in tunnels in deep geological formations. The heat emanated from the waste can drive the moisture flow transport and induce strongly coupled Thermal (T), Hydrological (H), Mechanical (M) and Chemical (C) processes within the bentonite buffer and may also impact the evolution of the excavation disturbed zone and the sealing between the buffer and walls of an emplacement tunnel The flow and contaminant transport potential along the disturbed zone can be minimized by backfilling the tunnels with bentonite, if it provides enough swelling stress when hydrated by the host rock. The swelling capability of clay minerals within the bentonite is important for sealing gaps between bentonite block, and between the EBS and the surrounding host rock. However, a high temperature could result in chemical alteration of bentonite-based buffer and backfill materials through illitization, which may compromise the function of these EBS components by reducing their plasticity and capability to swell under wetting. Therefore, an adequate THMC coupling scheme is required to understand and to predict the changes of bentonite for identifying whether EBS bentonite can sustain higher temperatures. More comprehensive links between chemistry and mechanics, taking advantage of the framework provided by a dual-structure model, named Barcelona Expansive Model (BExM), was implemented in TOUGHREACT-FLAC3D and is used to simulate the response of EBS bentonite in in clay formation for a generic case. The current work is to evaluate the chemical changes in EBS bentonite and the effects on the bentonite swelling stress under high temperature. This work sheds light on the interaction between THMC processes, evaluates the potential deterioration of EBS bentonite and supports the decision making in the design of a nuclear waste repository in light of the maximum allowance

  3. A cyclic bounding surface plasticity model for saturated clay with initial anisotropy%考虑饱和黏土初始各向异性的循环边界面塑性模型

    Institute of Scientific and Technical Information of China (English)

    胡存; 刘海笑

    2014-01-01

    天然土体的初始各向异性通常可对其后继循环特性产生显著影响。现有考虑循环载荷作用的土体弹塑性模型,往往采用类似修正剑桥模型的椭圆形屈服面,已有研究表明,该椭圆形屈服面因其拉伸弹性区域偏大,针对天然 K0固结状态的土体,其计算精度较差。基于新近提出的广义各向同性硬化准则,在边界面方程中引入初始各向异性张量,并采用空间滑动面破坏准则(SMP)的变换应力法,建立了能考虑饱和黏土初始各向异性的循环边界面塑性模型。分别针对等压和偏压固结的饱和黏土静、动三轴试验进行模拟,结果表明,该模型能合理反映土体的初始各向异性及其后继循环动力特性。%The initial anisotropy of natural soft clay tends to have a significant influence on its subsequent cyclic behaviors. The current elastoplastic constitutive models for cyclic behaviors of saturated clay always adopt an elliptic yield surface similar to the one in the modified Cam-clay model. However, studies have demonstrated that these kinds of models which adopt an elliptic yield surface are not suitable for predicting the characteristics of K0-consolidated soils under the extension state, due to its over-predicted elastic region. In this paper, within the framework of the generalized isotropic hardening rule, by introducing the initial anisotropic tensor to the formation of the bounding surface and combining with the transformed stress tensors which are based on the spatially mobilized plane (SMP) yield criterion, a new bounding surface plasticity model for saturated clay with initial anisotropy is proposed. The predicted results by the model for the monotonic and cyclic triaxial tests on both isotropically and anisotropically consolidated clays demonstrate that the bounding surface model can reasonably describe the initial anisotropy and the subsequent cyclic behaviors of saturated clay.

  4. Electrospun novel super-absorbent based on polysaccharide-polyvinyl alcohol-montmorillonite clay nanocomposites.

    Science.gov (United States)

    Islam, Md Shahidul; Rahaman, Md Saifur; Yeum, Jeong Hyun

    2015-01-22

    A novel super-absorbent material was fabricated by electrospinning the natural polysaccharide pullulan (PULL) with polyvinyl alcohol (PVA) and montmorillonite (MMT) clay to form nonwoven webs, which were then heat treated. Transmission electron microscopy (TEM) micrographs, X-ray diffraction (XRD) patterns, and Fourier transform infrared (FTIR) analysis of the novel super-absorbent nanofibers suggest the coexistence of PULL, PVA, and MMT through the exfoliation of MMT layers in the super-absorbent nanofiber composite. The heat-treated PULL/PVA/MMT webs loaded with 5 wt% MMT electrospun nanofibers exhibited a water absorbency of 143.42 g g(-1) in distilled water and a water absorbency of 39.75 g g(-1) in a 0.9 wt% NaCl solution. Under extremely dry conditions, the PULL/PVA/MMT webs exhibited the ability to retain 43% distilled water and 38% saline water after being exposed to the atmosphere for one week. The heat treatment improved the crystallinity of the electrospun PULL/PVA/MMT super-absorbent webs and thus made the webs highly stable in aqueous environments. Overall, the addition of MMT resulted in improved thermal stability and mechanical properties and increased the water absorbency of the PULL/PVA/MMT composite.

  5. Vane Shear Strength Based Stability Analysis of Slopes in Unconsolidated Soft Clay

    Institute of Scientific and Technical Information of China (English)

    刘润; 闫澍旺; 张连福

    2004-01-01

    In-situ vane shear test is frequently performed to determine shear strength for slope stability analysis in Tianjin New Harbor.However,the soil shear strength varies with the shear plane orientation.A possible means to reduce the effect of directional dependency of shear strength is to convert the in-situ vane shear strength into undrained shear strength parameters.A method of converting in-situ vane shear strength into undrained shear strength parameters is presented.The shear strength parameters determined for all of the in-situ vane shear strengths are subjected to statistical regression analysis to take into consideration the possible effect of non-homogeneity in the soft clay deposit.Using the regressed shear strength parameters,slope stability analyses are performed for five existing soil slopes.The results of stability analyses indicate that the safety factors obtained from the converted parameters reflect the state of the slopes analyzed much better than those obtained from in-situ vane shear strength and laboratory consolidated-undrained and unconsolidated-undrained strength parameters.It is concluded that the presented methsod of determining undrained shear strength parameters for in-situ vane shear strength is effective.

  6. Effective use of simple computer programmes and clay models to demonstrate the planning and operative steps for teaching and presentations

    Directory of Open Access Journals (Sweden)

    Rahul Krishnarao Patil

    2016-01-01

    Full Text Available Background: Presenting and demonstrating a surgical procedure in the current era is difficult without good intraoperative pictures and videos. A long, complex, multi-staged surgery is better illustrated by detailed intraoperative images at various stages. Although desirable, it may be difficult due to various reasons. Material and Methods: A simple method of preparing illustrations with pictures/diagrams created on PowerPoint and clay models to recreate the missing links in clinical photographs has been proposed. Results: It is a simple technique with a moderate learning curve. Once familiar with technique, one can effectively use the technique to convey the details in much more clear manner. Conclusion: It is a simple and effective way of communicating through digital images, and gives the audience a 3 dimensional idea about the concept.

  7. The Dependence of Castings Quality Produced in Clay Moulding Mixtures from the Properties of Binder Based on a Montmorillonite

    Directory of Open Access Journals (Sweden)

    Vasková I.

    2012-09-01

    Full Text Available Casting quality depends on many factors including the quality of the input materials, technology, material securing and last but not least, the mould into which the casting is casted. By pouring into a single-shot mould, based mainly on 1st generation binders, is is a very important factor. Basically, a bentonite mixture represents either a three- or four-component system, but each component of the system is a heterogeneous substance. This heterogeneity punctuates mainly a non-stationary heat field, presented throughout the whole process of the casting production. The most important component is a binder and in the case of first generation binders mostly bentonites are used - clays that contain minimum of 80% of montmorillonite.

  8. The Dependence of Castings Quality Produced in Clay Moulding Mixtures from the Properties of Binder Based on a Montmorillonite

    Directory of Open Access Journals (Sweden)

    I. Vasková

    2012-09-01

    Full Text Available Casting quality depends on many factors including the quality of the input materials, technology, material securing and last but notleast, the mould into which the casting is casted. By pouring into a single-shot mould, based mainly on 1st generation binders, is is a very important factor. Basically, a bentonite mixture represents either a three- or four-component system, but each component of the system is a heterogeneous substance. This heterogeneity punctuates mainly a non-stationary heat field, presented throughout the whole process of the casting production. The most important component is a binder and in the case of first generation binders mostly bentonites are used - clays that contain minimum of 80% of montmorillonite.

  9. Modelling the effects of pore-water chemistry on the behaviour of unsaturated clays

    Directory of Open Access Journals (Sweden)

    Lei Xiaoqin

    2016-01-01

    Full Text Available Due to their various applications in geo-environmental engineering, such as in landfill and nuclear waste disposals, the coupled chemo-hydro-mechanical analysis of expansive soils has gained more and more attention recently. These expansive soils are usually unsaturated under field conditions; therefore the capillary effects need to be taken into account appropriately. For this purpose, based on a rigorous thermodynamic framework (Lei et al., 2014, the authors have extended the chemo-mechanical model of Loret el al. (2002 for saturated homoionic expansive soils to the unsaturated case (Lei, 2015. In this paper, this chemo-mechanical unsaturated model is adopted to simulate the chemo-elastic-plastic consolidation process of an unsaturated expansive soil layer. Logical tendencies of changes in the chemical, mechanical and hydraulic field quantities are obtained.

  10. Effects of a thermal perturbation on mineralogy and pore water composition in a clay-rock: An experimental and modeling study

    Science.gov (United States)

    Gailhanou, H.; Lerouge, C.; Debure, M.; Gaboreau, S.; Gaucher, E. C.; Grangeon, S.; Grenèche, J.-M.; Kars, M.; Madé, B.; Marty, N. C. M.; Warmont, F.; Tournassat, C.

    2017-01-01

    The physical and chemical properties of clay-rocks are, at least partly, controlled by the chemical composition of their pore water. In evaluating the concept of disposing of radioactive waste in clay-rock formations, determining pore water composition is an important step in predicting how a clay-rock will behave over time and as a function of external forces, such as chemical and thermal perturbations. This study aimed to assess experimental and modeling methodology to calculate pore water composition in a clay-rock as a function of temperature (up to 80 °C). Hydrothermal alteration experiments were carried out on clay-rock samples. We conducted comprehensive chemical and mineralogical characterization of the material before and after reaction, and monitored how the chemical parameters in the liquid and gas phases changed. We compared the experimental results with the a priori predictions made by various models that differed in their hypotheses on the reactivity of the minerals present in the system. Thermodynamic equilibrium could not be assessed unequivocally in these experiments and most of the predicted mineralogy changes were too subtle to be tracked quantitatively. However, from observing the neo-formation of minerals such as goethite we were able to assess the prominent role of Fe-bearing phases in the outcome of the experiments, especially for the measured pH and pCO2 values. After calibrating the amount of reacting Fe-bearing phases with our data, we proposed a thermodynamic model that was capable of predicting the chemical evolution of the systems under investigation as well as the evolution of other systems already published in the literature, with the same clay-rock material but with significant differences in experimental conditions.

  11. Efficiency of clay--TiO2 nanocomposites on the photocatalytic elimination of a model hydrophobic air pollutant.

    Science.gov (United States)

    Kibanova, Daria; Cervini-Silva, Javiera; Destaillats, Hugo

    2009-03-01

    Clay-supported TiO2 photocatalysts can potentially improve the performance of air treatment technologies via enhanced adsorption and reactivity of target volatile organic compounds (VOCs). In this study, a benchtop photocatalytic flow reactor was used to evaluate the efficiency of hectorite-TiO2 and kaolinite-TiO2, two novel composite materials synthesized in our laboratory. Toluene, a model hydrophobic VOC and a common indoor air pollutant, was introduced in the air stream at realistic concentrations, and reacted under UVA (lamda(max) = 365 nm) or UVC (lamda(max) = 254 nm) irradiation. The UVC lamp generated secondary emission at 185 nm, leading to the formation of ozone and other short-lived reactive species. Performance of clay-Ti02 composites was compared with that of pure TiO2 (Degussa P25), and with UV irradiation in the absence of photocatalyst under identical conditions. Films of clay-TiO2 composites and of P25 were prepared by a dip-coating method on the surface of Raschig rings, which were placed inside the flow reactor. An upstream toluene concentration of approximately 170 ppbv was generated by diluting a constant flow of toluene vapor from a diffusion source with dry air, or with humid air at 10, 33, and 66% relative humidity (RH). Toluene concentrations were determined by collecting Tenax-TA sorbent tubes downstream of the reactor, with subsequent thermal desorption--GC/MS analysis. The fraction of toluene removed, %R, and the reaction rate, Tr, were calculated for each experimental condition from the concentrations measured with and without UV irradiation. Use of UVC light (UV/TiO2/O3) led to overall higher reactivity, which can be partially attributed to the contribution of gas phase reactions by short-lived radical species. When the reaction rate was normalized to the light irradiance, Tr/Ilamda,the UV/TiO2 reaction under UVA irradiation was more efficient for samples with a higher content of TiO2 (P25 and Hecto-TiO2), but notfor Kao-TiO2. In all

  12. Aerosol Radiative Forcing Estimates from South Asian Clay Brick Production Based on Direct Emission Measurements

    Science.gov (United States)

    Weyant, C.; Athalye, V.; Ragavan, S.; Rajarathnam, U.; Kr, B.; Lalchandani, D.; Maithel, S.; Malhotra, G.; Bhanware, P.; Thoa, V.; Phuong, N.; Baum, E.; Bond, T. C.

    2012-12-01

    About 150-200 billion clay bricks are produced in India every year. Most of these bricks are fired in small-scale traditional kilns that burn coal or biomass without pollution controls. Reddy and Venkataraman (2001) estimated that 8% of fossil fuel related PM2.5 emissions and 23% of black carbon emissions in India are released from brick production. Few direct emissions measurements have been done in this industry and black carbon emissions, in particular, have not been previously measured. In this study, 9 kilns representing five common brick kiln technologies were tested for aerosol properties and gaseous pollutant emissions, including optical scattering and absorption and thermal-optical OC/EC. Simple relationships are then used to estimate the radiative-forcing impact. Kiln design and fuel quality greatly affect the overall emission profiles and relative climate warming. Batch production kilns, such as the Downdraft kiln, produce the most PM2.5 (0.97 gPM2.5/fired brick) with an OC/EC fraction of 0.3. Vertical Shaft Brick kilns using internally mixed fuels produce the least PM (0.09 gPM2.5/kg fired brick) with the least EC (OC/EC = 16.5), but these kilns are expensive to implement and their use throughout Southern Asia is minimal. The most popular kiln in India, the Bull's Trench kiln, had fewer emissions per brick than the Downdraft kiln, but an even higher EC fraction (OC/EC = 0.05). The Zig-zag kiln is similar in structure to the Bull's Trench kiln, but the emission factors are significantly lower: 50% reduction for CO, 17% for PM2.5 and 60% for black carbon. This difference in emissions suggests that converting traditional Bull's Trench kilns into less polluting Zig-zag kilns would result in reduced atmospheric warming from brick production.

  13. Constraints on the sealing capacity of faults with clay smears from discrete element models validated by laboratory experiments

    NARCIS (Netherlands)

    Terheege, J.H.; Wassing, B.B.T.; Orlic, B.; Giger, S.B.; Clennell, M.B.

    2013-01-01

    Prediction of hydrocarbon column heights in structural traps critically depends on proper analysis of the sealing capacity of faults. Entrainment of clay in fault zones in upper crustal levels may lead to the development of continuous clay smears that dramatically increase the sealing capacity of fa

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-09-15

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

  15. Effect of clay structure and type of organomodifier on the thermal properties of poly(ethylene terephthalate) based nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Papageorgiou, George Z.; Karandrea, Eva; Giliopoulos, Dimitrios [Department of Chemistry, Aristotle University of Thessaloniki (AUTH), GR-54124 Thessaloniki (Greece); Papageorgiou, Dimitrios G. [Solid State Physics Department, School of Physics, Aristotle University of Thessaloniki AUTH, GR-54124 Thessaloniki (Greece); Ladavos, Athanasios; Katerinopoulou, Aikaterini [University of Patras, Agrinio 30100 (Greece); Achilias, Dimitris S.; Triantafyllidis, Konstantinos S. [Department of Chemistry, Aristotle University of Thessaloniki (AUTH), GR-54124 Thessaloniki (Greece); Bikiaris, Dimitrios N., E-mail: dbic@chem.auth.gr [Department of Chemistry, Aristotle University of Thessaloniki (AUTH), GR-54124 Thessaloniki (Greece)

    2014-01-20

    Graphical abstract: - Highlights: • Poly(ethylene terephthalate) nanocomposites were prepared using 4 different clay types. • Nanomer I30E clay was exfoliated into PET, as it was found from XRD. • The intercalation of Kunipia-CTAB resulted in less pronounced effect on PET crystallization. • The immobilized amorphous fraction, activation energy and nucleation activity were calculated. • Nanomer I30E clay facilitated the crystallization process. - Abstract: In the current investigation, nanocomposites of poly(ethylene terephthalate) (PET) with different types of organo-clays were produced using the melt mixing technique. Two types of commercial inorganic clays (Laponite-synthetic hectorite and Kunipia-montmorillonite) were studied after cation-exchange with hexadecyltrimethylammonium bromide (CTAB) while two commercial organo-modified montmorillonite clays (Nanomer I.30E modified with primary octadecylammonium ions and Cloisite 10A modified with quaternary dimethyl benzyl hydrogenated-tallow ammonium ions) were also investigated. The structure of the nanocomposites was studied by X-ray diffraction measurements. A detailed crystallization analysis was carried out by means of both isothermal and non-isothermal (melt and cold) measurements. All data were analyzed using the simple Avrami equation along with advanced isoconversional methods. The nucleation activity of the filler was investigated in every case. Lauritzen–Hoffman analysis was employed to isothermal data to estimate the nucleation parameters. From all these measurements it was found that the organo-clay I.30E induces the higher crystallization rates and lower activation energy and is more effective regarding the PET crystallization compared to the other types of organo-clays. The I.30E organo-clay nanocomposite exhibited also the higher immobilized amorphous fraction and the higher nucleation parameter K{sub g} in the Lauritzen–Hoffman analysis. This is due to its better dispersion and

  16. The Implementation of Clay Modeling and Rat Dissection into the Human Anatomy and Physiology Curriculum of a Large Urban Community College

    Science.gov (United States)

    Haspel, Carol; Motoike, Howard K.; Lenchner, Erez

    2014-01-01

    After a considerable amount of research and experimentation, cat dissection was replaced with rat dissection and clay modeling in the human anatomy and physiology laboratory curricula at La Guardia Community College (LAGCC), a large urban community college of the City University of New York (CUNY). This article describes the challenges faculty…

  17. The Implementation of Clay Modeling and Rat Dissection into the Human Anatomy and Physiology Curriculum of a Large Urban Community College

    Science.gov (United States)

    Haspel, Carol; Motoike, Howard K.; Lenchner, Erez

    2014-01-01

    After a considerable amount of research and experimentation, cat dissection was replaced with rat dissection and clay modeling in the human anatomy and physiology laboratory curricula at La Guardia Community College (LAGCC), a large urban community college of the City University of New York (CUNY). This article describes the challenges faculty…

  18. Ceramic clays from the western part of the Tamnava Tertiary Basin, Serbia: Deposits and clay types

    Directory of Open Access Journals (Sweden)

    Radosavljević Slobodan

    2014-01-01

    Full Text Available Based on geological, mineralogical, physical, chemical and technological investigations in the Tamnava Tertiary Basin near Šabac town (western Serbia, deposits of ceramic clays were studied. These ceramic clays are composed of kaolin-illite with a variable content of quartz, feldspars, mica, iron oxides and hydroxides, and organic matter. Four main types of commercial clays were identified: i red-yellow sandy-gravely (brick clays; ii grey-white poor sandy (ceramic clays; iii dark-carbonaceous (ceramic clays; and iv lamellar (“interspersed” fatty, poor sandy (highly aluminous and ferrous clays. Ceramic clays are defined as medium to high plastic with different ranges of sintering temperatures, which makes them suitable for the production of various kinds of materials in the ceramic industry. [Projekat Ministarstva nauke Republike Srbije, br. OI-176016

  19. Unraveling the antibacterial mode of action of a clay from the Colombian Amazon.

    Science.gov (United States)

    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.

  20. Geochemical of clay formations : study of Spanish clay REFERENCE; Geoquimica de formaciones arcillosas: estudio de la Arcilla Espanola de REFERENCE

    Energy Technology Data Exchange (ETDEWEB)

    Turrero, M. J.; Pena, J.

    2003-07-01

    Clay rocks are investigated in different international research programs in order to assess its feasibility for the disposal of high level radioactive wastes. This is because different sepcific aspects: they have low hydraulic conductivity (10''-11-10''-15 m/s), a high sorption capacity, self-sealing capacity of facults and discontinuities and mechanical resistance. Several research programs on clay formations are aimed to study the chemistry of the groundwater and the water-rock reactions that control it: e. g. Boom Clay (Mol, Belgium), Oxford Clay /Harwell, United Kingdom), Toarcian Clay (Tournemire, France), Palfris formation (Wellenberg, Switzerland), Opalinus Clay (Bure, France). Based on these studies, consdierable progress in the development of techniques for hydrologic, geochemical and hydrogeochemical characterization of mudstones has been accomplished (e. g. Beaufais et al. 1994, De Windt el al. 1998. Thury and Bossart 1999, Sacchi and Michelot 2000) with important advances in the knowledge of geochemical process in these materials (e. g. Reeder et al. 1993, Baeyens and Brandbury 1994, Beaucaire et al. 2000, Pearson et al., 2003).Furtermore, geochemical modeling is commonly used to simulate the evolution of water chemistry and to understand quantitatively the processescontrolling the groundwater chemistry (e. g. Pearson et al. 1998, Tempel and Harrison 2000, Arcos et al., 2001). The work presented here is part of a research program funded by Enresa in the context of its R&D program. It is focused on the characterization of a clay formation (reference Argillaceous Formation, RAF) located within the Duero Basin (north-centralSpain). The characterisation of th ephysical properties,, fluid composition, mineralogy, water-rock reaction processes, geochemical modelling and sorption properties of the clays from the mentioned wells is the main purpose of this work. (Author)

  1. Reactive transport modelling of a heating and radiation experiment in the Boom clay (Belgium); Modelo de transporte reactivo de un experimento con calor y radiacion en la arcilla de Boom (Belgica)

    Energy Technology Data Exchange (ETDEWEB)

    Montenegro, L.; Samper, J.; Delgado, J.

    2003-07-01

    Most countries around the world consider Deep Geological Repositories (DGR) as the most safe option for the final disposal of high level radioactive waste (HLW). DGR is based on adopting a system of multiple barriers between the HLW and the biosphere. Underground laboratories provide information about the behaviour of these barriers at real conditions. Here we present a reactive transport model for the CERBERUS experiment performed at the HADES underground laboratory at Mol (Belgium) in order to characterize the thermal (T), hydrodynamic (H) and geochemical (G) behaviour of the Boon clay. This experiment is unique because it addresses the combined effect of heat and radiation produced by the storage of HLW in a DGR. Reactive transport models which are solved with CORE, are used to perform quantitative predictions of Boom clay thermo-hydro-geochemical (THG) behaviour. Numerical results indicate that heat and radiation cause a slight oxidation near of the radioactive source, pyrite dissolution, a pH decrease and slight changes in the pore water chemical composition of the Boom clay. (Author) 33 refs.

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

    Science.gov (United States)

    Hosokawa, Hitoshi; Mochida, Tomoyuki

    2015-12-01

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

  3. Clay at Nili Fossae

    Science.gov (United States)

    2006-01-01

    , the small mesa -- a flat-topped hill -- at the center of the image is a remnant of an overlying rock layer that was eroded away. The greenish clay areas at the base of the hill were exposed by erosion of the overlying rock. The images at the upper right and lower left both show that the reddish-toned olivine occurs as sand dunes on top of the greenish clay deposits. The image at the lower right shows details of the clay-rich rock, including that they are extensively fractured into small, polygonal blocks just a few meters in size. Taken together, the CRISM and HiRISE data show that the clay-rich rocks are the oldest at the site, that they are exposed where overlying rock has been eroded away, and that the olivine is not part of the clay-rich rock. Rather it occurs in sand dunes blowing across the clay. Many more images of Nili Fossae and other clay-rich areas will be taken over the next two years. They will be used to try to understand the earliest climate of Mars that is recorded in the planet's rocks. The Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) is one of six science instruments on NASA's Mars Reconnaissance Orbiter. Led by The Johns Hopkins University Applied Physics Laboratory, the CRISM team includes expertise from universities, government agencies and small businesses in the United States and abroad. CRISM's mission: Find the spectral fingerprints of aqueous and hydrothermal deposits and map the geology, composition and stratigraphy of surface features. The instrument will also watch the seasonal variations in Martian dust and ice aerosols, and water content in surface materials o leading to new understanding of the climate. NASA's Jet Propulsion Laboratory, a division of the Califonia Institute of Technology, Pasadena, manages the Mars Reconnaissance Orbiter for the NASA Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, is the prime contractor and built the spacecraft.

  4. Contours of Corcoran Clay Depth in feet from Page (1986) for the Central Valley Hydrologic Model (CVHM)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This digital dataset defines the depth of the Corcoran Clay Member of the Tulare Formation. The complex hydrologic system of the Central Valley is simulated using...

  5. Investigations of Near-Field Thermal-Hydrologic-Mechanical-Chemical Models for Radioactive Waste Disposal in Clay/Shale Rock

    Energy Technology Data Exchange (ETDEWEB)

    Liu, H.H.; Li, L.; Zheng, L.; Houseworth, J.E.; Rutqvist, J.

    2011-06-20

    Clay/shale has been considered as potential host rock for geological disposal of high-level radioactive waste throughout the world, because of its low permeability, low diffusion coefficient, high retention capacity for radionuclides, and capability to self-seal fractures. 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 the Mol site, Belgium (Barnichon and Volckaert, 2003) have all been under intensive scientific investigation (at both field and laboratory scales) for understanding a variety of rock properties and their relationships to flow and transport processes associated with geological disposal of radioactive waste. Figure 1-1 presents the distribution of clay/shale formations within the USA.

  6. Contours of Corcoran Clay Thickness in feet by Page (1986) for the Central Valley Hydrologic Model (CVHM)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This digital dataset defines the thickness of the Corcoran Clay Member of the Tulare Formation. The complex hydrologic system of the Central Valley is simulated...

  7. Adhesion of silver nanoparticles on the clay substrates; modeling and experiment

    Energy Technology Data Exchange (ETDEWEB)

    Tokarsky, Jonas, E-mail: jonas.tokarsky.fmmi@vsb.cz [Nanotechnology Centre, VSB-Technical University Ostrava, 17. listopadu 15/2172, 708 33 Ostrava (Czech Republic); Capkova, Pavla [Nanotechnology Centre, VSB-Technical University Ostrava, 17. listopadu 15/2172, 708 33 Ostrava (Czech Republic); Rafaja, David; Klemm, Volker [Institute of Materials Science, TU Bergakademie Freiberg, Gustav-Zeuner-Street 5, D-09599 Freiberg (Germany); Valaskova, Marta; Kukutschova, Jana; Tomasek, Vladimir [Nanotechnology Centre, VSB-Technical University Ostrava, 17. listopadu 15/2172, 708 33 Ostrava (Czech Republic)

    2010-02-15

    Adhesion of silver nanoparticles on the montmorillonite and kaolinite substrates has been investigated using molecular modeling (force field calculations) that enabled the estimation and comparison of adhesion energies for Ag/montmorillonite and Ag/kaolinite nanocomposites and revealed the preferred orientation of Ag nanoparticles on the silicate substrates. Results of the modeling have been confronted with experiment (X-ray fluorescence, high-resolution transmission electron microscopy). This confrontation has shown that the results of the modeling are consistent with the experimental data and illustrated the capability of the molecular modeling for prediction of the nanoparticles orientation, structure and stability of the nanoparticle/substrate nanocomposite.

  8. Anionic clay as the drug delivery vehicle: tumor targeting function of layered double hydroxide-methotrexate nanohybrid in C33A orthotopic cervical cancer model.

    Science.gov (United States)

    Choi, Goeun; Piao, Huiyan; Alothman, Zeid A; Vinu, Ajayan; Yun, Chae-Ok; Choy, Jin-Ho

    2016-01-01

    Methotrexate (MTX), an anticancer agent, was successfully intercalated into the anionic clay, layered double hydroxides to form a new nanohybrid drug. The coprecipitation and subsequent hydrothermal method were used to prepare chemically, structurally, and morphologically well-defined two-dimensional drug-clay nanohybrid. The resulting two-dimensional drug-clay nanohybrid showed excellent colloidal stability not only in deionized water but also in an electrolyte solution of Dulbecco's Modified Eagle's Medium with 10% fetal bovine serum, in which the average particle size in colloid and the polydispersity index were determined to be around 100 and 0.250 nm, respectively. The targeting property of the nanohybrid drug was confirmed by evaluating the tumor-to-blood and tumor-to-liver ratios of the MTX with anionic clay carrier, and these ratios were compared to those of free MTX in the C33A orthotopic cervical cancer model. The biodistribution studies indicated that the mice treated with the former showed 3.5-fold higher tumor-to-liver ratio and fivefold higher tumor-to-blood ratio of MTX than those treated with the latter at 30 minutes postinjection.

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

    Science.gov (United States)

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

    2013-08-01

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

  10. 描述黏粒含量对土-水特征曲线影响规律的分形模型%A fractal model describing the relation between clay content and soil-water characteristic curve

    Institute of Scientific and Technical Information of China (English)

    陶高梁; 张季如; 庄心善; 杨琳

    2014-01-01

    Clay content of soil has an important influence on soil-water characteristic curve. To establish a theoretical model describing the influence of clay content on soil-water characteristic curve, the relation be-tween the clay content and fractal dimension in terms of mass has been established by means of a fractal theory. This relation was verified by test data and used to explain the basic rule that the fractal dimension increases with the increase of clay content. On this basis, a fractal model which reflects the influence of clay content on soil-water characteristic curve was suggested based on the previous results. The results show that the soil-water characteristic curves predicted by the model are in good agreement with several tests data. The model was applied to predict the soil-water characteristic curves of some soils with different clay content and shows the influence of clay content on the soil-water characteristic curve, i.e., large clay content corresponds to large water content of volume in the case of same soil suction.%土体黏粒含量对土-水特征曲线有重要影响。为了建立描述黏粒含量对土-水特征曲线影响规律的理论模型,本文基于分形理论,建立了质量分维数与黏粒含量的关系式,利用已有试验数据验证了该式的合理性,并从理论上解释了质量分维数随黏粒含量增大的基本规律。在此基础上,结合已有的研究成果,建立了分形模型描述土体黏粒含量对土-水特征曲线影响规律,该模型预测的土-水特征曲线与已有不同土类样本的试验数据吻合较好,从而证明了该模型的有效性。最后,利用该模型同时预测了不同黏粒含量典型土体的土-水特征曲线,阐明了黏粒含量对土-水特征曲线影响的基本规律,即相同吸力条件下,黏粒含量越高,则体积含水率越高。

  11. Modeling of Fecal Coliform Bacteria in Surface Drip Irrigationin Clay Loam Soil

    Directory of Open Access Journals (Sweden)

    foroogh abbasi teshnizi

    2017-03-01

    Full Text Available Water for agriculture is one of the most important factors in arid and semi-arid areas and municipal wastewater treatment is an important resource for this purpose. Therefore, potential of transfer contaminations is a serious problem regarding use of treated wastewater for agriculture. Due to the risk of transfer contaminations through the use of wastewater, the study of transfer microbes in soil in recent decades has been of interest to researchers. In the present study, the transfer of bacteria fecal coliform was investigated in a lysimeter and the HYDRUS-1D model was used to simulate water flow and the fecal coliform in the soil. For calibration of the model and estimating the model input parameters, soil hydraulic and transport parameters, were inversely estimated. Results represented that the HYDRUS-1D with reasonably accurately simulated the outlet flow. To simulate the transfer of the bacteria in the soil, one site sorption model, two kinetic sites model (particle transport using attachment/detachment and one kinetic site model were used. In the simulation of bacterial transfer, one site sorption model was selected as the proper model for this study. One site sorption model estimated solid-phase growth coefficient ( about sextuple more than liquid-phase. It showed that deposited cells had a higher division rate compared with the cell in liquid-phase. The calibrated model was used for surveying the effect various irrigation intervals and irrigation times on bacterial transfer. The results showed that by increasing irrigation times, more bacteria leached out from the soil. Also by increasing irrigation intervals, more bacteria observed in the soil profile, due to favorable environmental conditions and food for the bacteria growth. According to the results, the best interval and irrigation times were one day and four hours, respectively.

  12. Efficiency of clay-TiO2 nanocomposites on the photocatalytic eliminationof a model hydrophobic air pollutant

    Energy Technology Data Exchange (ETDEWEB)

    Kibanova, Daria; Cervini-Silva, Javiera; Destaillats, Hugo

    2009-01-01

    Clay-supported TiO2 photocatalysts can potentially improve the performance of air treatment technologies via enhanced adsorption and reactivity of target volatile organic compounds (VOCs). In this study, a bench-top photocatalytic flow reactor was used to evaluate the efficiency of hectorite-TiO2 and kaolinite-TiO2, two novel composite materials synthesized in our laboratory. Toluene, a model hydrophobic VOC and a common indoor air pollutant, was introduced in the air stream at realistic concentrations, and reacted under UVA (gamma max = 365 nm) or UVC (gamma max = 254 nm) irradiation. The UVC lamp generated secondary emission at 185 nm, leading to the formation of ozone and other short-lived reactive species. Performance of clay-TiO2 composites was compared with that of pure TiO2 (Degussa P25), and with UV irradiation in the absence of photocatalyst under identical conditions. Films of clay-TiO2 composites and of P25 were prepared by a dip-coating method on the surface of Raschig rings, which were placed inside the flow reactor. An upstream toluene concentration of ~;;170 ppbv was generated by diluting a constant flow of toluene vapor from a diffusion source with dry air, or with humid air at 10, 33 and 66percent relative humidity (RH). Toluene concentrations were determined by collecting Tenax-TA (R) sorbent tubes downstream of the reactor, with subsequent thermal desorption -- GC/MS analysis. The fraction of toluene removed, percentR, and the reaction rate, Tr, were calculated for each experimental condition from the concentration changes measured with and without UV irradiation. Use of UVC light (UV/TiO2/O3) led to overall higher reactivity, which can be partially attributed to the contribution of gas phase reactions by short-lived radical species. When the reaction rate was normalized to the light irradiance, Tr/I gamma, the UV/TiO2 reaction under UVA irradiation was more efficient for samples with a higher content of TiO2 (P25 and Hecto-TiO2), but not for Kao

  13. Filtration of triazine herbicides by polymer-clay sorbents: coupling an experimental mechanistic approach with empirical modeling.

    Science.gov (United States)

    Gardi, Ido; Nir, Shlomo; Mishael, Yael G

    2015-03-01

    Triazine herbicides detected in surface and groundwater pose environmental and health risks. Removal of triazine herbicides (simazine, atrazine and terbuthylazine) by polymer-clay composites was studied and modeled. Their binding by a poly 4-vinyl pyridine co styrene-montmorillonite (HPVP-CoS-MMT) composite was especially high due to specific interactions between the herbicides and polymer, mainly hydrogen bonds and π-π stacking. The binding kinetics to the composite was in the order of simazine > atrazine > terbuthylazine, which was in accord with their equilibrium Langmuir binding coefficients; 44,000, 17,500 and 16,500 M(-1), respectively, which correlated with herbicide accessibility to form specific interaction with the polymer. Simazine binding kinetics to the composite was significantly faster than to granulated activated carbon (GAC), reaching 93% vs 38% of the maximal adsorption within 10 min, respectively. Herbicide filtration by composite columns was adequately fitted by a model which considers convection and employs Langmuir formalism for kinetics of adsorption/desorption. Filtration of simazine (10 μg L(-1)) by composite columns (40 cm long, which included 26 g composite mixed with sand 1:40 (weight ratio)), was well predicted by the model with nearly 120 L purified, i.e., effluent concentrations were below regulation limit (3 μg L(-1)). Effluent concentrations from GAC columns exceeded the limit after filtering 5 L. Experimental results and model predictions suggest that while GAC has a high capacity for simazine binding, the composite has higher affinity towards the herbicide and its adsorption is faster, which yields more efficient filtration by composite columns.

  14. Membrane behavior of clay liner materials

    Science.gov (United States)

    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.

  15. Probing the water interactions in clay

    Energy Technology Data Exchange (ETDEWEB)

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

    1999-11-01

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

  16. Far Field Sorption Data Bases for Performance Assessment of a High-Level Radioactive Waste Repository in an Undisturbed Opalinus Clay Host Rock

    Energy Technology Data Exchange (ETDEWEB)

    Bradburry, M.; Baeyens, B

    2003-08-01

    An Opalinus Clay formation in the Zuercher Weinland is under consideration by Nagra as a potential location for a high-level and long-Iived intermediate-level radioactive waste repository. Performance assessment studies will be performed for this site and the purpose of this report is to describe the procedures used to develop sorption data bases appropriate for an undisturbed Opalinus Clay host rock which are required for such safety analysis calculations. In tight, low water content argillaceous rock formations such as Opalinus Clay, there is uncertainty concerning the in situ pH/P{sub CO{sub 2}}. In order to take this intrinsic uncertainty into account porewater chemistries were calculated for a reference case, pH = 7.24, and for two other pH values, 6.3 and 7.8. Sorption data bases are given for the three cases. The basis for the sorption data bases is 'in-house' sorption measurements for Cs(I), Sr(II), Ni(II), Eu(III), Sn(IV), Se(IV), Th(IV) and I(-I) carried out on Opalinus Clay samples from Mont Terri (Canton Jura) since at the time the experiments were performed no core samples from the Benken borehole (Zuercher Weinland) were available. The Opalinus Clay at Mont Terri and Benken are part of the same geological formation . Despite having directly measured data for the above key radionuclides, some of the required distribution ratios (Rd) used to generate the sorption data bases still came from the open literature. An important part of this report is concerned with describing the procedures whereby these selected literature Rd values were modified so as to apply to the Benken Opalinus Clay mineralogy and groundwater chemistries calculated at the three pH values given above. The resulting Rd values were then further modified using so-called Lab{yields}Field transfer factors to produce sorption values which were appropriate to the in situ bulk rock for the selected range of water chemistry conditions. Finally, it is important to have some

  17. Anionic clay as the drug delivery vehicle: tumor targeting function of layered double hydroxide-methotrexate nanohybrid in C33A orthotopic cervical cancer model

    Directory of Open Access Journals (Sweden)

    Choi G

    2016-01-01

    Full Text Available Goeun Choi,1 Huiyan Piao,1 Zeid A Alothman,2 Ajayan Vinu,3 Chae-Ok Yun,4 Jin-Ho Choy1 1Center for Intelligent Nano-Bio Materials, Department of Chemistry and Nano Science, Ewha Womans University, Seoul, Korea; 2Advanced Materials Research Chair, Chemistry Department, College of Science, King Saud University, Riyadh, Saudi Arabia; 3Future Industries Institute, University of South Australia, Mawson Lakes, SA, Australia; 4Department of Bioengineering, College of Engineering, Hanyang University, Seoul, Korea Abstract: Methotrexate (MTX, an anticancer agent, was successfully intercalated into the anionic clay, layered double hydroxides to form a new nanohybrid drug. The coprecipitation and subsequent hydrothermal method were used to prepare chemically, structurally, and morphologically well-defined two-dimensional drug-clay nanohybrid. The resulting two-dimensional drug-clay nanohybrid showed excellent colloidal stability not only in deionized water but also in an electrolyte solution of Dulbecco’s Modified Eagle’s Medium with 10% fetal bovine serum, in which the average particle size in colloid and the polydispersity index were determined to be around 100 and 0.250 nm, respectively. The targeting property of the nanohybrid drug was confirmed by evaluating the tumor-to-blood and tumor-to-liver ratios of the MTX with anionic clay carrier, and these ratios were compared to those of free MTX in the C33A orthotopic cervical cancer model. The biodistribution studies indicated that the mice treated with the former showed 3.5-fold higher tumor-to-liver ratio and fivefold higher tumor-to-blood ratio of MTX than those treated with the latter at 30 minutes postinjection. Keywords: anionic clay, biodistribution, cervical cancer, colloidal stability, layered double hydroxide, methotrexate 

  18. Cholesterol Biosensor Based on Entrapment of Monoenzyme and Multienzymes in Clay/Chitosan Hybrid Matrix

    Institute of Scientific and Technical Information of China (English)

    Dan Shan; YanNa Wang; HuaiGuo Xue; En Han

    2009-01-01

    @@ This work aimed at showing the interest of the composite material based on layered double hydroxides(LDHs) and chitosan (CHT) as suitable host matrix likely to immobilize enzyme onto electrode surface for amperometric biosensing application.This hybrid material combined the advantages of inorganic LDHs and organic biopolymer,CHT.

  19. Pesticide leaching in polders : field and model studies on cracked clays and loamy sand

    NARCIS (Netherlands)

    Groen, K.P.

    1997-01-01

    This thesis reports on a study of pesticide leaching in polder areas. The study comprises two aspects: a data collection program and the development, calibration and application of the model SWACRO for the simulation of pesticide transport.

    Field data were

  20. Mars, clays and the origins of life

    Science.gov (United States)

    Hartman, Hyman

    1989-01-01

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

  1. Formulation and characterization of polyethylenes and organo-clays. Barrier properties of the obtained nano-composites; Formulation et caracterisation de polyethylenes charges avec des argiles. Proprietes barriere des nanocomposites obtenus

    Energy Technology Data Exchange (ETDEWEB)

    Wache, R.

    2004-10-01

    The particularity of polymer layered silicate nano-composites is based on the exfoliation of the clay platelets in the polymer matrix. Therefore properties may be dramatically modified with very low clay loading. In this work polyethylene and organo-clay have been melt blended. Due to a lack of polarity, the polymer chains do not intercalate the clay stacking. However exfoliation is achieved using maleate polyethylene. We used this polymer as a compatibilizer to promote clay exfoliation in the polyethylene matrix. Partial exfoliation is obtained. Barrier properties of these materials have been characterized. Permeability is higher for the clay reinforced products than their matrix. To understand the poor permeability results a tortuosity model has been developed. The quality of the interface seems to be involved. Several organo-clays and compatibilizers have been tested to improve it. But for the concentrations of these products used polyethylene clay interactions always exist and lead to an increase of diffusion. (author)

  2. Clay-filled bio-based blends of poly(lactic acid) and polyamide 11

    Science.gov (United States)

    Nuzzo, Anna; Acierno, Domenico; Filippone, Giovanni

    2012-07-01

    We investigate the effect of small amounts of organoclay on the crystallinity and dynamic-mechanical properties of bio-based blends of poly(lactic acid) (PLA) and polyamide 11 (PA11). Virgin and filled blends were prepared by melt-compounding the constituents using a twin-screw extruder. Wettability considerations suggest that the filler unevenly distribute inside the material. This affect both the crystallinity of each phase and the blend microstructure. Controlling such phenomena can lead to highly "engineerized" materials with tailored properties. In particular, the typically poor mechanical performances of bio-based polymers can be overcame owing to the synergism among reinforcing action of the filler, its possible compatibilizing action and its impact on the crystallinity of the hosting phase.

  3. Obtaining the porewater composition of a clay rock by modeling the in- and out-diffusion of anions and cations from an in-situ experiment.

    Science.gov (United States)

    Appelo, C A J; Vinsot, A; Mettler, S; Wechner, S

    2008-10-23

    A borehole in the Callovo-Oxfordian clay rock in ANDRA's underground research facility was sampled during 1 year and chemically analyzed. Diffusion between porewater and the borehole solution resulted in concentration changes which were modeled with PHREEQC's multicomponent diffusion module. In the model, the clay rock's pore space is divided in free porewater (electrically neutral) and diffuse double layer water (devoid of anions). Diffusion is calculated separately for the two domains, and individually for all the solute species while a zero-charge flux is maintained. We explain how the finite difference formulas for radial diffusion can be translated into mixing factors for solutions. Operator splitting is used to calculate advective flow and chemical reactions such as ion exchange and calcite dissolution and precipitation. The ion exchange reaction is formulated in the form of surface complexation, which allows distributing charge over the fixed sites and the diffuse double layer. The charge distribution affects pH when calcite dissolves, and modeling of the experimental data shows that about 7% of the cation exchange capacity resides in the diffuse double layer. The model calculates the observed concentration changes very well and provides an estimate of the pristine porewater composition in the clay rock.

  4. Implementation and Validation of an Anisotropic Plasticity Model for Clay and a Two-Scale Micropolar Constitutive Model for Sand

    Science.gov (United States)

    Yonten, Karma

    As a multi-phase material, soil exhibits highly nonlinear, anisotropic, and inelastic behavior. While it may be impractical for one constitutive model to address all features of the soil behavior, one can identify the essential aspects of the soil's stress-strainstrength response for a particular class of problems and develop a suitable constitutive model that captures those aspects. Here, attention is given to two important features of the soil stress-strain-strength behavior: anisotropy and post-failure response. An anisotropic soil plasticity model is implemented to investigate the significance of initial and induced anisotropy on the response of geo-structures founded on cohesive soils. The model is shown to produce realistic responses for a variety of over-consolidation ratios. Moreover, the performance of the model is assessed in a boundary value problem in which a cohesive soil is subjected to the weight of a newly constructed soil embankment. Significance of incorporating anisotropy is clearly demonstrated by comparing the results of the simulation using the model with those obtained by using an isotropic plasticity model. To investigate post-failure response of soils, the issue of strain localization in geostructures is considered. Post-failure analysis of geo-structures using numerical techniques such as mesh-based or mesh-free methods is often faced with convergence issues which may, at times, lead to incorrect failure mechanisms. This is due to the fact that majority of existing constitutive models are formulated within the framework of classical continuum mechanics that leads to ill-posed governing equations at the onset of localization. To overcome this challenge, a critical state two-surface plasticity model is extended to incorporate the micro-structural mechanisms that become significant within the shear band. The extended model is implemented to study the strain localization of granular soils in drained and undrained conditions. It is demonstrated

  5. Radionuclide interaction with clays in dilute and heavily compacted systems: a critical review.

    Science.gov (United States)

    Miller, Andrew W; Wang, Yifeng

    2012-02-21

    Given the unique properties of clays (i.e., low permeability and high ion sorption/exchange capacity), clays or clay formations have been proposed either as an engineered material or as a geologic medium for nuclear waste isolation and disposal. A credible evaluation of such disposal systems relies on the ability to predict the behavior of these materials under a wide range of thermal-hydrological-mechanical-chemical (THMc) conditions. Current model couplings between THM and chemical processes are simplistic and limited in scope. This review focuses on the uptake of radionuclides onto clay materials as controlled by mineral composition, structure, and texture (e.g., pore size distribution), and emphasizes the connections between sorption chemistry and mechanical compaction. Variable uptake behavior of an array of elements has been observed on various clays as a function of increasing compaction due to changes in pore size and structure, hydration energy, and overlapping electric double layers. The causes for this variability are divided between "internal" (based on the fundamental structure and composition of the clay minerals) and "external" (caused by a force external to the clay). New techniques need to be developed to exploit known variations in clay mineralogy to separate internal from external effects.

  6. The modeling method of diffusion of radio activated materials in clay waste disposals

    Energy Technology Data Exchange (ETDEWEB)

    Saberi, Reza; Sepanloo, Kamran [NSTRI, Tehran (Iran, Islamic Republic of); Alinejad, Majid [Engineering Research Institute of Natural Hazard, Isfahan (Iran, Islamic Republic of); Mozaffari, Ali [KNT Univ. of Technology, Tehran (Iran, Islamic Republic of)

    2017-02-15

    New nuclear power plants are necessary to meet today's and future challenges of energy supply. Nuclear power is the only large-scale energy source that takes full responsibility for all its wastes. Nuclear wastes are particularly hazardous and hard to manage relative to different toxic industrial wastes. Three methods are presented and analysed to model the diffusion of the waste from the waste disposal to the bottom surface. For this purpose three software programmes such as ABAQUS, Matlab coding, Geostudio and ArcGIS have been applied.

  7. Cytotoxicity and mechanical behavior of chitin-bentonite clay based polyurethane bio-nanocomposites.

    Science.gov (United States)

    Zia, Khalid Mahmood; Zuber, Mohammad; Barikani, Mehdi; Hussain, Rizwan; Jamil, Tahir; Anjum, Sohail

    2011-12-01

    Chitin based polyurethane bio-nanocomposites (PUBNC) were prepared using chitin, Delite HPS bentonite nanoclay enriched in montmorillonite (MMT), 4,4'-diphenylmethane diisocyanate (MDI) and polycaprolactone polyol CAPA 231 (3000 g/mol(-1)). The prepolymers having different concentration of Delite HPS bentonite nanoclay were extended with 2 moles of chitin. The structures of the resulted polymers were determined by FT-IR technique. The effect of nanoclay contents on mechanical properties and in vitro biocompatibility was investigated. The mechanical properties of the synthesized materials were improved with increase in the Delite HPS bentonite nanoclay contents. Optimum mechanical properties were obtained from the PU bio-nanocomposite samples having 4% Delite HPS bentonite nanoclay. The results revealed that the final PU bio-nanocomposite having 2% Delite HPS bentonite nanoclay contents is ideal contenders for surgical threads with on going investigations into their in vitro biocompatibility, non-toxicity, and mechanical properties.

  8. The Fuzzy Logic Model for the Prediction of Marshall Stability of Lightweight Asphalt Concretes Fabricated using Expanded Clay Aggregate

    Directory of Open Access Journals (Sweden)

    Sercan SERİN

    2014-07-01

    Full Text Available In the study, predictability of Marshall Stability (MS of light asphalt concrete that fabricated using expanded clay and had varied mix properties with Fuzzy Logic (FL were researched. With this aim, asphalt concrete samples that added expanded clay aggregate (EC in accordance with gradation determined in Highway Technical Specification, had different percentage of bitumen (POB (4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, 10.5% and unit weight (UW (1,75–1,87 (gr/cm3 were prepared and determined Marshall stabilities with Marshall test

  9. Synthesis of polyurethane/clay nanocomposites based palm oil polyol coating

    Directory of Open Access Journals (Sweden)

    Teuku Rihayat

    2015-12-01

    Full Text Available In this study, we investigated the Polyurethane paint based on palm oil with the addition of nanoparticles montmorillonite as a heat-resistant. The composites with 1 wt%, 3 wt% and 5 wt% of bentonite filler content obtained by synthesizing in situ were investigated and compared to the neat polyurethane matrix material. The processing of bentonite for montmorillonite was done through several stages including: sedimentation, ultrasonication, dried, sieved with a 200 mesh sieve, then characterized. Untreated MMT were isolated and modified with CTAB. The addition of MMT into polyurethane, as much as 5% wt, can increase the heat as evidenced by the TGA test. The TGA results indicated an enhanced thermal stability, as compared to the neat polyurethane. The onset degradation of neat polyurethane and weight reduction began at a temperature of 50-150°C and completely decomposed at the temperatures of 380°C and for PU MKS-MMT reduction, the initial weight started at a temperature of 150-200°C in 5 %wt and decomposed in the end at a temperature of 490°C. In this research, we also tested the gloss adhesive polyurethane with the addition of MMT; the result stated that the addition of 5%wt MMT can improve the adhesion of polyurethane. The addition of MMT in polyurethane can also enhance the gloss polyurethane compared with polyurethane coated without the addition of MMT.

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

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, Olav

    1997-12-31

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

  11. Moessbauer Spectra of Clays and Ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, F. E.; Wagner, U. [Technische Universitaet Muenchen (Germany)

    2004-06-15

    The physical, chemical and mineralogical aspects of the use of Moessbauer spectroscopy in studies of clay-based ceramics are described. Moessbauer spectra of pottery clays fired under oxidising, reducing and changing conditions are explained, and the possibilities of using Moessbauer spectra to derive information on the firing temperatures and the kiln atmosphere during firing in antiquity are discussed and illustrated by examples.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  13. Orbital evidence for clay and acidic sulfate assemblages on Mars based on mineralogical analogs from Rio Tinto, Spain

    Science.gov (United States)

    Kaplan, Hannah H.; Milliken, Ralph E.; Fernández-Remolar, David; Amils, Ricardo; Robertson, Kevin; Knoll, Andrew H.

    2016-09-01

    Outcrops of hydrated minerals are widespread across the surface of Mars, with clay minerals and sulfates being commonly identified phases. Orbitally-based reflectance spectra are often used to classify these hydrated components in terms of a single mineralogy, although most surfaces likely contain multiple minerals that have the potential to record local geochemical conditions and processes. Reflectance spectra for previously identified deposits in Ius and Melas Chasma within the Valles Marineris, Mars, exhibit an enigmatic feature with two distinct absorptions between 2.2 and 2.3 μm. This spectral 'doublet' feature is proposed to result from a mixture of hydrated minerals, although the identity of the minerals has remained ambiguous. Here we demonstrate that similar spectral doublet features are observed in airborne, field, and laboratory reflectance spectra of rock and sediment samples from Rio Tinto, Spain. Combined visible-near infrared reflectance spectra and X-ray diffraction measurements of these samples reveal that the doublet feature arises from a mixture of Al-phyllosilicate (illite or muscovite) and jarosite. Analyses of orbital data from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) shows that the martian spectral equivalents are also consistent with mixtures of Al-phyllosilicates and jarosite, where the Al-phyllosilicate may also include kaolinite and/or halloysite. A case study for a region within Ius Chasma demonstrates that the relative proportions of the Al-phyllosilicate(s) and jarosite vary within one stratigraphic unit as well as between stratigraphic units. The former observation suggests that the jarosite may be a diagenetic (authigenic) product and thus indicative of local pH and redox conditions, whereas the latter observation may be consistent with variations in sediment flux and/or fluid chemistry during sediment deposition.

  14. Wetland eco-engineering: measuring and modeling feedbacks of oxidation processes between plants and clay-rich material

    Science.gov (United States)

    Saaltink, Rémon; Dekker, Stefan C.; Griffioen, Jasper; Wassen, Martin J.

    2016-09-01

    Interest is growing in using soft sediment as a foundation in eco-engineering projects. Wetland construction in the Dutch lake Markermeer is an example: here, dredging some of the clay-rich lake-bed sediment and using it to construct wetland will soon begin. Natural processes will be utilized during and after construction to accelerate ecosystem development. Knowing that plants can eco-engineer their environment via positive or negative biogeochemical plant-soil feedbacks, we conducted a 6-month greenhouse experiment to identify the key biogeochemical processes in the mud when Phragmites australis is used as an eco-engineering species. We applied inverse biogeochemical modeling to link observed changes in pore water composition to biogeochemical processes. Two months after transplantation we observed reduced plant growth and shriveling and yellowing of foliage. The N : P ratios of the plant tissue were low, and these were affected not by hampered uptake of N but by enhanced uptake of P. Subsequent analyses revealed high Fe concentrations in the leaves and roots. Sulfate concentrations rose drastically in our experiment due to pyrite oxidation; as reduction of sulfate will decouple Fe-P in reducing conditions, we argue that plant-induced iron toxicity hampered plant growth, forming a negative feedback loop, while simultaneously there was a positive feedback loop, as iron toxicity promotes P mobilization as a result of reduced conditions through root death, thereby stimulating plant growth and regeneration. Given these two feedback mechanisms, we propose the use of Fe-tolerant species rather than species that thrive in N-limited conditions. The results presented in this study demonstrate the importance of studying the biogeochemical properties of the situated sediment and the feedback mechanisms between plant and soil prior to finalizing the design of the eco-engineering project.

  15. Reconstruction of late Quaternary monsoon oscillations based on clay mineral proxies using sediment cores from the western margin of India

    Digital Repository Service at National Institute of Oceanography (India)

    Thamban, M.; Rao, V.P.; Schneider, R.R.

    - nental margin. As the hinterland is characterised by steep slopes with heavy monsoon rainfall, it is presumed that clays were not stored on land for periods more than the duration of the millennial- scale climatic £uctuations we attempt to interpret...

  16. Biopolymer blends based on polylactic acid and polyhydroxy butyrate-co-valerate: effect of clay on mechanical and thermal properties

    CSIR Research Space (South Africa)

    John, MJ

    2015-11-01

    Full Text Available as an additive was used to make the blends. The effects of three different types of clay (montmorillonite, bentonite, and chemically modified bentonite) on the mechanical and thermal properties of the blends were studied. The ratio of PLA and PHBV (w...

  17. Wetland eco-engineering: Measuring and modeling feedbacks of oxidation processes between plants and clay-rich material

    NARCIS (Netherlands)

    Saaltink, R.; Dekker, S.C.; Griffioen, J.; Wassen, M.J.

    2016-01-01

    Interest is growing in using soft sediment as a foundation in eco-engineering projects. Wetland construction in the Dutch lake Markermeer is an example: here, dredging some of the clay-rich lake-bed sediment and using it to construct wetland will soon begin. Natural processes will be utilized during

  18. Wetland eco-engineering: measuring and modeling feedbacks of oxidation processes between plants and clay-rich material

    NARCIS (Netherlands)

    Saaltink, R.M.; Dekker, S.C.; Griffioen, J.; Wassen, M.J.

    2016-01-01

    Interest is growing in using soft sediment as a foundation in eco-engineering projects. Wetland construction in the Dutch lake Markermeer is an example: here, dredging some of the clay-rich lake-bed sediment and using it to construct wetland will soon begin. Natural processes will be utilized during

  19. Human Clay Models versus Cat Dissection: How the Similarity between the Classroom and the Exam Affects Student Performance

    Science.gov (United States)

    Waters, John R.; Van Meter, Peggy; Perrotti, William; Drogo, Salvatore; Cyr, Richard J.

    2011-01-01

    This study examined the effect of different anatomic representations on student learning in a human anatomy class studying the muscular system. Specifically, we examined the efficacy of using dissected cats (with and without handouts) compared with clay sculpting of human structures. Ten undergraduate laboratory sections were assigned to three…

  20. Human Clay Models versus Cat Dissection: How the Similarity between the Classroom and the Exam Affects Student Performance

    Science.gov (United States)

    Waters, John R.; Van Meter, Peggy; Perrotti, William; Drogo, Salvatore; Cyr, Richard J.

    2011-01-01

    This study examined the effect of different anatomic representations on student learning in a human anatomy class studying the muscular system. Specifically, we examined the efficacy of using dissected cats (with and without handouts) compared with clay sculpting of human structures. Ten undergraduate laboratory sections were assigned to three…

  1. Effects of Fiber Reinforcement on Clay Aerogel Composites

    Directory of Open Access Journals (Sweden)

    Katherine A. Finlay

    2015-08-01

    Full Text Available Novel, low density structures which combine biologically-based fibers with clay aerogels are produced in an environmentally benign manner using water as solvent, and no additional processing chemicals. Three different reinforcing fibers, silk, soy silk, and hemp, are evaluated in combination with poly(vinyl alcohol matrix polymer combined with montmorillonite clay. The mechanical properties of the aerogels are demonstrated to increase with reinforcing fiber length, in each case limited by a critical fiber length, beyond which mechanical properties decline due to maldistribution of filler, and disruption of the aerogel structure. Rather than the classical model for reinforced composite properties, the chemical compatibility of reinforcing fibers with the polymer/clay matrix dominated mechanical performance, along with the tendencies of the fibers to kink under compression.

  2. Biodegradable Pectin/clay Aerogels

    Science.gov (United States)

    Biodegradable, foamlike materials based on renewable pectin and sodium montmorillonite clay were fabricated through a simple, environmentally friendly freeze-drying process. Addition of multivalent cations (Ca2+ and Al3+) resulted in apparent crosslinking of the polymer, and enhancement of aerogel p...

  3. Prediction of clay content from water vapour sorption isotherms considering hysteresis and soil organic matter content

    DEFF Research Database (Denmark)

    Arthur, Emmanuel; Tuller, Markus; Moldrup, Per

    2015-01-01

    for estimating clay content from hygroscopic water at different relative humidity (RH) levels while considering hysteresis and organic matter content. Continuous adsorption/desorption vapour sorption isotherm loops were measured for 150 differently textured soils with a state-of-the-art vapour sorption analyser......Soil texture, in particular the clay fraction, governs numerous environmental, agricultural and engineering soil processes. Traditional measurement methods for clay content are laborious and impractical for large-scale soil surveys. Consequently, clay prediction models that are based on water...... vapour sorption, which can be measured within a shorter period of time, have recently been developed. Such models are often based on single-point measurements of water adsorption and do not account for sorption hysteresis or organic matter content. The present study introduces regression relationships...

  4. Thermostability of montmorillonitic clays

    OpenAIRE

    Petr Jelínek; Dobosz, Stanisław M.; Jaroslav Beňo

    2014-01-01

    Bentonite is one of the most widespread used clays connected with various applications. In the case of foundry technology, bentonite is primarily used as a binder for mold manufacture. Thermal stability of bentonites is a natural property of clay minerals and it depends on the genesis, source and chemical composition of the clay. This property is also closely connected to bentonite structure. According to DTA analysis if only one peak of dehydroxylation is observed (about 600 ºC), the cis- is...

  5. Thermal and mechanical properties of palm oil-based polyurethane acrylate/clay nanocomposites prepared by in-situ intercalative method and electron beam radiation

    Energy Technology Data Exchange (ETDEWEB)

    Salih, A. M. [Department of Chemistry, Faculty of Science, University Putra Malaysia 43400, UPM, Serdang, Selangor, Malaysia and Department of Radiation Processing, Sudan Atomic Energy Commission, Khartoum 1111 (Sudan); Ahmad, Mansor Bin; Ibrahim, Nor Azowa [Department of Chemistry, Faculty of Science, University Putra Malaysia 43400, UPM, Serdang, Selangor (Malaysia); Dahlan, Khairul Zaman Hj Mohd [Polycomposite Sdn Bhd, No.75-2, Jalan TKS 1, Taman Kajang Sentral, 43000 Kajang, Selangor (Malaysia); Tajau, Rida [Radiation Processing Technology Division, Nuclear Malaysia, Bangi, 43000 Kajang, Selangor (Malaysia); Mahmood, Mohd Hilmi [No. 107, Jalan 2, Taman Kajang Baru, Sg Jelok, 43000 Kajang, Selangor (Malaysia); Yunus, Wan Md. Zin Wan [Department of Chemistry, Centre for Defence Foundation Studies, National Defence University of Malaysia, 57000, Sungai Besi Camp, Kuala Lumpur (Malaysia)

    2014-02-12

    Palm oil based-polyurethane acrylate (POBUA)/clay nanocomposites were prepared via in-situ intercalative polymerization using epoxidized palm oil acrylate (EPOLA) and 4,4' methylene diphenyl diisocyante (MDI). Organically modified Montmorillonite (ODA-MMT) was incorporated in EPOLA (1, 3 and 5%wt), and then subjected to polycondensation reaction with MDI. Nanocomposites solid films were obtained successfully by electron beam radiation induced free radical polymerization (curing). FTIR results reveal that the prepolymer was obtained successfully, with nanoclay dispersed in the matrix. The intercalation of the clay in the polymer matrix was investigated by XRD and the interlayer spacing of clay was found to be increased up to 37 Å, while the structure morphology of the nanocomposites was investigated by TEM and SEM. The nanocomposites were found to be a mixture of exfoliated and intercalated morphologies. The thermal stability of the nanocomposites was significantly increased by incorporation of nanoclay into the polymer matrix. DSC results reveal that the Tg was shifted to higher values, gradually with increasing the amount of filler in the nanocomposites. Tensile strength and Young's modulus of the nanocomposites showed remarkable improvement compared to the neat POBUA.

  6. Characterization of groundwater dynamics in landslides in varved clays

    NARCIS (Netherlands)

    Van der Spek, J.E.; Bogaard, T.A.; Bakker, M.

    2013-01-01

    Groundwater dynamics may play a significant role in landslides. A detailed model is developed of the groundwater dynamics in landslides in varved clays in the Trièves area in the French Alps. The varved clays consist of a sequence of alternating silt and clay layers, covered by a colluvium layer and

  7. Characterization of groundwater dynamics in landslides in varved clays

    NARCIS (Netherlands)

    Van der Spek, J.E.; Bogaard, T.A.; Bakker, M.

    2013-01-01

    Groundwater dynamics may play a significant role in landslides. A detailed model is developed of the groundwater dynamics in landslides in varved clays in the Trieves area in the French Alps. The varved clays consist of a sequence of alternating silt and clay layers, covered by a colluvium layer and

  8. Study of smectite clays of the city Pedra Lavrada - PB for use in water-based drilling fluids; Estudo das argilas esmectiticas do municipio de Pedra Lavrada-PB para uso em fluidos de perfuracao base agua

    Energy Technology Data Exchange (ETDEWEB)

    Silva, I.A. da; Costa, J.M.R.; Cardoso, M.A.F.; Neves, G.A.; Ferreira, H.C., E-mail: isabelle_albuquerquecg@hotmail.com [Universidade Federal de Campina Grande (UAEMa/CCT/UFCG), PB (Brazil). Unidade Academica de Engenharia de Materiais; Ferreira, H.S. [Universidade Federal da Paraiba (DEMAT/CT/UFPB), Joao Pessoa, PB (Brazil)

    2011-07-01

    Paraiba has large reserves of bentonite clays, with the largest deposits in Boa Vista, PB. Recently new deposits were discovered in the cities of Cubati and Pedra Lavrada-PB, creating great expectations for further expansion of reserves for industrial production. The aim of this work is the study of smectite clays from the city of Pedra Lavrada, PB for use in drilling fluids water based. The characterization was made by the diffraction of laser (AG), thermogravimetric and differential thermal analysis (TGA and DTA), chemical composition by X-ray fluorescence (EDX), X-ray diffraction (XRD), exchange capacity of cations (ECC) and surface area (SA). The results obtained so far showed that the samples presented at its mineral composition smectite, kaolinite and quartz. In relation to rheological properties showed that the bentonite clay sample Dark presents promising features for use in water based drilling fluids. (author)

  9. Organophilization of bentonite clays with non-ionic surfactants aiming their use in drilling fluids base oil; Organofilizacao de argilas bentoniticas com tensotivo nao-ionico visando seu uso em fluidos de perfuracao base oleo

    Energy Technology Data Exchange (ETDEWEB)

    Silva, I.A.; Costa, J.M.R.; Neves, G.A.; Ferreira, H.C. [Universidade Federal de Campina Grande (UAEMa/CCT/UFCG), PB (Brazil). Unidade Academica de Engenharia de Materiais; Ferreira, H.S. [Universidade Federal da Paraiba (DEMAT/CT/UFPB), Joao Pessoa, PB (Brazil). Dept. de Materiais

    2010-07-01

    The use of nonionic surfactants has been replacing the traditional ionic surfactants among others by its high potential for resistance to thermal degradation. This work aims at the development of organoclay by the addition of nonionic surfactants for use in drilling fluids for oil wells based oil. The bentonite clay was organophilized and then characterized by X-ray diffraction and swelling Foster, seeking the most appropriate choice of surfactant to liquid organic dispersing media: ester, diesel and paraffin. With the obtained dispersions were measured apparent viscosities and plastic. The results showed that incorporation of surfactants used in the clay interlayer spacing increased significantly and that the dispersions showed rheological properties within the specifications of PETROBRAS, for the use of organophilic clays in drilling fluids in a non-aqueous base. (author)

  10. A generalized viscoelastic Biot/squirt model for clay-bearing sandstones in a wide range of permeabilities%适用于更广渗透率范围含泥质砂岩的广义粘弹性BISQ模型

    Institute of Scientific and Technical Information of China (English)

    聂建新; 杨顶辉; 杨慧珠

    2008-01-01

    To simultaneously take into account the Biot-flow mechanism, the squirt-flow mechanism, and the frame-viscoelasticity mechanism, a generalized viscoelastic BISQ (Biot/squirt) model is developed for wave propagation in clay-bearing sandstones based on Dvorkin's elastic BISQ model. The present model is extended to a wide range of permeabilities (k>0.05 mD) by introducing a dimensionless correction factor for viscoelastic parameters, defined as a function of the permeability and the clay content. We describe the frame's stress-strain relationship of the clay-bearing sandstones by the differential constitutive equations of generalized viscoelasticity and then derive the viscoelastic-wave dynamic equations. With the assumption of a plane-wave solution, we finally yield the phase velocities and the attenuation coefficients by solving the dynamic wave equations in the frequency and wave number domain. The comparison of numerical results and experimental data shows that the generalized viscoelastic BISQ model is applicable for modeling the wave propagation in most of the sandstones mainly bearing kaolinite clay.

  11. Vulnerability of shallow ground water and drinking-water wells to nitrate in the United States: Model of predicted nitrate concentration in shallow, recently recharged ground water -- Input data set for clay sediment (gwava-s_clay)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set represents the amount of clay sediment in the soil, in percent times 1000, in the conterminous United States. The data set was used as an input data...

  12. Study on applicability of clay-based grout injection in the excavated damaged zone around the plug (TSX project)

    Energy Technology Data Exchange (ETDEWEB)

    Sugita, Yutaka [Japan Nuclear Cycle Development Inst., Tokai, Ibaraki (Japan). Tokai Works

    2002-09-01

    JNC has joined the international joint project, the TSX project, with AECL at the Underground Research Laboratory (URL) in Canada. Full-scale sealing technologies are applied to an underground tunnel in the TSX project. Regarding clay grouting, which supports the performance of the clay plug, a grouting experiment in the Excavated Damaged Zone around the tunnel was performed in the TSX project. A pre-injection test was the trial for the development of the grouting procedure, and the injection test was to evaluate the grouting effectiveness of the grouting in the EDZ around the tunnel. The results of the experiments showed the efficiency injection concentration of the grout slurry was between 4.0 and 6.0wt%. Grouted EDZ had lower hydraulic conductivity than that before grouting. (author)

  13. Effect of addition of organo clay on mechanical properties and dynamic-mechanical based TPV; Preparacao de termoplasticos vulcanizados dinamicamente (TPV) de NBR/PP com nanocargas de argila

    Energy Technology Data Exchange (ETDEWEB)

    Honorato, Luciana R.; Silva, Adriana A.; Soares, Bluma G. [Universidade Federal do Rio de Janeiro - UFRJ, Instituto de Macromoleculas Professora Eloisa Mano, Rio de Janeiro, RJ (Brazil); Soares, Ketly P. [Centro Universitario do Leste de Minas Gerais (UNILESTEMG) - Coronel Fabriciano, MG (Brazil)

    2011-07-01

    The effect of organophilic clay on the mechanical and dynamical-mechanical properties of thermoplastic elastomers based on polypropylene (PP) and nitrile rubber (NBR) was investigated. The addition of clay was performed from a master batch prepared by a solution intercalation of NBR inside the clay galleries. Since the PP/NBR blend is highly incompatible, PP functionalized with maleic anhydride (PP-g-MA) and carboxylated NBR (XNBR) were employed as compatibilizing system together with triethylene-tetramine (TETA) used as coupling agent. The addition of Clay inside the elastomeric phase of the TPV resulted in a significant decrease of the elongation at break without changes on the tensile strength. The presence of clay also promoted a slight increase of the storage modulus and the glass transition temperature. The small angle X ray scattering confirmed the high dispersion of clay inside the TPV. Analysis of light scattering small angle (SAXS) confirmed the high dispersion of clay in the matrix of the TPV. (author)

  14. Permeation properties of polymer/clay nanocomposites

    Science.gov (United States)

    Kalendova, A.; Merinska, D.; Gerard, J. F.

    2012-07-01

    The important characteristics of polymer/clay nanocomposites are stability, barrier properties and in the case of polyvinyl chloride also plasticizer migration into other materials. Therefore, the permeation properties of polymer/clay nanocomposites are discussed in this paper. The attention was focused to the polyethylene (PE) and polyvinyl chloride (PVC). Natural type of montmorillonite MMTNa+ and modified types of montmorillonite from Southern Clay Products were used as the inorganic phase. As the compounding machine, one screw Buss KO-kneader was employed. The principal aim is to fully exfoliate the clay into polymer matrix and enhanced the permeation properties. Prepared samples were tested for O2 and CO2 permeability. Polymer/clay nanocomposite structure was determined on the base of X-ray diffraction and electron microscopy (TEM).

  15. A performance-based method for calculating the design thickness of compacted clay liners exposed to high strength leachate under simulated landfill conditions.

    Science.gov (United States)

    Safari, Edwin; Jalili Ghazizade, Mahdi; Abdoli, Mohammad Ali

    2012-09-01

    Compacted clay liners (CCLs) when feasible, are preferred to composite geosynthetic liners. The thickness of CCLs is typically prescribed by each country's environmental protection regulations. However, considering the fact that construction of CCLs represents a significant portion of overall landfill construction costs; a performance based design of liner thickness would be preferable to 'one size fits all' prescriptive standards. In this study researchers analyzed the hydraulic behaviour of a compacted clayey soil in three laboratory pilot scale columns exposed to high strength leachate under simulated landfill conditions. The temperature of the simulated CCL at the surface was maintained at 40 ± 2 °C and a vertical pressure of 250 kPa was applied to the soil through a gravel layer on top of the 50 cm thick CCL where high strength fresh leachate was circulated at heads of 15 and 30 cm simulating the flow over the CCL. Inverse modelling using HYDRUS-1D indicated that the hydraulic conductivity after 180 days was decreased about three orders of magnitude in comparison with the values measured prior to the experiment. A number of scenarios of different leachate heads and persistence time were considered and saturation depth of the CCL was predicted through modelling. Under a typical leachate head of 30 cm, the saturation depth was predicted to be less than 60 cm for a persistence time of 3 years. This approach can be generalized to estimate an effective thickness of a CCL instead of using prescribed values, which may be conservatively overdesigned and thus unduly costly.

  16. Water and clay based drilling fluids: rheologic, filtration and lubricity behavior; Fluidos hidroargilosos: comportamento reologico, de filtracao e lubricidade

    Energy Technology Data Exchange (ETDEWEB)

    Amorim, Luciana V.; Pereira, Melquesedek S.; Ferreira, Heber C. [Universidade Federal de Campina Grande (UFCG), PB (Brazil)

    2008-07-01

    The aim of this work is to provide continuity for UFCG studies presenting results of rheological, filtration and the lubricity behaviors obtained with fluids prepared with bentonite clays from Paraiba, in binary compositions, after treatment with lubricants agents. It was selected two samples of bentonite clays and four lubricants (Lub 1, Lub 2, Lub 3 and Lub 4). The results showed that: depending on the composition, the drilling fluids presented bingham and pseudo plastic rheological behaviors, and with the additives bingham behavior; among the rheological and filtration properties evaluated, the apparent viscosity, yield limiting and the water loss are the have changes with the addition of lubricants; the values of the lubricity coefficient (LC) of fluids without additives were next of 0.50, independent of the composition of the bentonite clay mixture; after addition of the lubricants, the LC of fluids reduced for values next to 0,11, independent of its concentration and lubricants the best-performing are the Lub 2 and Lub 4. (author)

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

    Directory of Open Access Journals (Sweden)

    Feng-shan Zhou

    2015-01-01

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

  18. Modeling the arrangement of particles in natural swelling-clay porous media using three-dimensional packing of elliptic disks.

    Science.gov (United States)

    Ferrage, Eric; Hubert, Fabien; Tertre, Emmanuel; Delville, Alfred; Michot, Laurent J; Levitz, Pierre

    2015-06-01

    Swelling clay minerals play a key role in the control of water and pollutant migration in natural media such as soils. Moreover, swelling clay particles' orientational properties in porous media have significant implications for the directional dependence of fluid transfer. Herein we investigate the ability to mimic the organization of particles in natural swelling-clay porous media using a three-dimensional sequential particle deposition procedure [D. Coelho, J.-F. Thovert, and P. M. Adler, Phys. Rev. E 55, 1959 (1997)]. The algorithm considered is first used to simulate disk packings. Porosities of disk packings fall onto a single master curve when plotted against the orientational scalar order parameter value. This relation is used to validate the algorithm used in comparison with existing ones. The ellipticity degree of the particles is shown to have a negligible effect on the packing porosity for ratios ℓ(a)/ℓ(b) less than 1.5, whereas a significant increase in porosity is obtained for higher values. The effect of the distribution of the geometrical parameters (size, aspect ratio, and ellipticity degree) of particles on the final packing properties is also investigated. Finally, the algorithm is used to simulate particle packings for three size fractions of natural swelling-clay mineral powders. Calculated data regarding the distribution of the geometrical parameters and orientation of particles in porous media are successfully compared with experimental data obtained for the same samples. The results indicate that the obtained virtual porous media can be considered representative of natural samples and can be used to extract properties difficult to obtain experimentally, such as the anisotropic features of pore and solid phases in a system.

  19. An in vitro Assessment on the Efficacy of Clay-Based Formulated Cells of Pseudomonas Isolate UTAR EPA2 for Petrol Degradation

    Directory of Open Access Journals (Sweden)

    A. S.Y. Ting

    2010-01-01

    Full Text Available Problem statement: Application of free-cell forms is usually impractical to achieve satisfactory bioremediative effect because the microbes are encumbered by the biotic and abiotic stresses from the environment. Approach: In this study, a hydrocarbon-degrading bacterium (Pseudomonas isolate UTAR EPA2 was formulated with various combinations of formulative materials, comprising of clay-based carrier materials such as Bentonite (B and Kaolin (K, enrichment materials such as Non-fat skimmed milk (N and Sucrose (S and a UV-protectant agent Para-aminobenzoic acid (P. Formulated cells were treated to sunlight exposure for 6 h to mimic the conditions in the environment prior to testing for their efficacy in degrading petrol, a mixed hydrocarbon substrate. Results: Cells in all formulations including free-cell suspension were able to degrade petrol with a relatively high degradation efficacy of more than 66% even after exposure to sunlight. Degradation efficacy was slightly higher for kaolin-based formulated cells compared to bentonite-based formulations, especially after exposure to sunlight, although their percentages of degradation were not statistically different. Nevertheless, kaolin-based formulations have very low viable cell count especially in formulations with P (KP, KNP, KSP, KNSP. This suggested that aside from viable cells, the physical properties of the clays could have also contributed to the degradation of petrol. Conclusion: For storage purposes and applications in the field, we suggest that the bacterium is formulated with bentonite-based formulations especially using Bentonite (B clay singly, as relatively high percentage of petrol degradation and viable cell count was achieved with this formulation.

  20. Predicting soil particle density from clay and soil organic matter contents

    DEFF Research Database (Denmark)

    Schjønning, Per; McBride, R.A.; Keller, T.

    2017-01-01

    Soil particle density (Dp) is an important soil property for calculating soil porosity expressions. However, many studies assume a constant value, typically 2.65Mgm−3 for arable, mineral soils. Fewmodels exist for the prediction of Dp from soil organic matter (SOM) content. We hypothesized...... of clay particles was approximately 2.86 Mg m−3, while that of sand+silt particles could be estimated to ~2.65 Mgm−3. Multiple linear regression showed that a combination of clay and SOMcontents could explain nearly 92% of the variation in measured Dp. The clay and SOMprediction equation was validated...... against a combined data set with 227 soil samples representing A, B, and C horizons from temperate North America and Europe. The new prediction equation performed better than two SOM-based models from the literature. Validation of the new clay and SOM model using the 227 soil samples gave a root mean...

  1. Clay Portrait Boxes

    Science.gov (United States)

    Wilbert, Nancy Corrigan

    2009-01-01

    In an attempt to incorporate sculptural elements into her ceramics program, the author decided to try direct plaster casting of the face to make a plaster mold for clay. In this article, the author shares an innovative ceramics lesson that teaches students in making plaster casts and casting the face in clay. This project gives students the…

  2. Columns in Clay

    Science.gov (United States)

    Leenhouts, Robin

    2010-01-01

    This article describes a clay project for students studying Greece and Rome. It provides a wonderful way to learn slab construction techniques by making small clay column capitols. With this lesson, students learn architectural vocabulary and history, understand the importance of classical architectural forms and their influence on today's…

  3. Clay Mineral: Radiological Characterization

    Science.gov (United States)

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

    2008-08-01

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

  4. Hands-on Virtual Clay

    OpenAIRE

    Pihuit, Adeline; Kry, Paul; Cani, Marie-Paule

    2008-01-01

    poster; International audience; This paper presents a new interaction system designed for hands-on 3D shape modeling and deformation through natural hand gestures. Our system is made of a Phantom haptic device coupled with a deformable foam ball that supports pressure sensors. These sensors detect forces exerted by the user's fingertips, and are used to control the configuration of a compliant virtual hand that is modeling soft virtual clay. During interaction, the user is provided both passi...

  5. Siderophore sorption to clays.

    Science.gov (United States)

    Maurice, Patricia A; Haack, Elizabeth A; Mishra, Bhoopesh

    2009-08-01

    Siderophores are low molecular weight organic ligands exuded by some aerobic organisms and plants to acquire Fe under Fe-limited conditions. The hydroxamate siderophores may sorb to aluminosilicate clays through a variety of mechanisms depending upon the nature of the clay and of the siderophore along with solution conditions such as pH, ionic strength, and presence of metal cations. They may also affect metal binding to clays. Here, we review previous studies of siderophore sorption to aluminosilicate clays; briefly discuss how the techniques of X-ray diffractometry, Fourier-transform infrared spectroscopy, and X-ray absorption spectroscopy may be applied to such studies; review effects of siderophores on metal sorption to clays; and highlight some areas for future research.

  6. A hydrogeological study of the confined aquifers below the Boom Clay in NE-Belgium: combining a piezometric analysis with groundwater modelling

    Science.gov (United States)

    Vandersteen, Katrijn; Gedeon, Matej

    2013-04-01

    For more than 35 years, SCKCEN has been investigating the possibility of high-level and/or long-lived radioactive waste disposal in the Boom Clay in north-eastern Belgium. This research, defined in the long term management programme for high-level and/or long-lived waste of ONDRAF/NIRAS, includes studying the regional hydrogeology of the aquifer systems surrounding the Boom Clay. In this context, a hydrogeological study of the confined aquifers below the Boom Clay was performed. To properly address the conceptual uncertainties related to the poorly characterized domain featuring large uncertainty in the forcing data, a combination of a piezometric data analysis and hydrogeological modelling was used. The study area represents the confined part of the groundwater system located stratigraphically below the Boom Clay in NE-Belgium. This so-called deep aquifer system includes, with increasing depth, parts of the Oligocene aquifer, the Bartoon aquitard system and the Ledo-Paniselian-Brusselian aquifer. Due to the considerable pumping from these aquifers in combination with a limited recharge to the deep aquifer system, a gradual decrease in groundwater levels has been observed in more than 30-year piezometric records. The analysis of the piezometry of the confined deep aquifer system allowed gaining more insight on the system response to the intensive pumping. Since the Oligocene aquifer has a significantly lower permeability compared to the Ledo-Paniselian-Brusselian aquifer, the Oligocene pumping triggers only local effects on groundwater levels. Hence, the regional effects (constant decrease of groundwater levels) in the Oligocene aquifer are presumably caused by pumping in the Ledo-Paniselian-Brusselian aquifer, whereby the hydraulically isolating Maldegem Formation (Bartoon aquitard) dampens these effects. The amount of this dampening is given by the spatial distribution of the hydraulic properties of the Maldegem Formation and/or its variable thickness. For the

  7. Physicochemical analysis of clays and ceramics of the regional state of Calakmul: production models, distribution and consumption; Analisis fisicoquimico de arcillas y ceramicos del estado regional de Calakmul: modelos de produccion, distribucion y consumo

    Energy Technology Data Exchange (ETDEWEB)

    Dominguez C, M.R.; Folan, W.J. [Centro de Investigaciones Historicas y Sociales, Universidad Autonoma de Campeche, Campeche (Mexico); Espinosa P, M.E. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico); Rodriguez L, V. [CUV, BUAP, 72000 Puebla (Mexico)

    2005-07-01

    This work presents the final results of the research project 'Sources, production and consumption of ceramics in the regional state of Calakmul: a socio-political approach', with the proposal of models of production and ceramic specialization as well as of distribution and consumption of these goods in the territory that occupied the regional state of Calakmul, with base in the typological analysis of the ceramics of Calakmul and 72 sites registered in its environs as well as in comparative studies with ceramics of other greater sites near Calakmul and complemented with the application of analytical techniques in the study of clays and sherds diagnoses of the Mayan Classic period. These models were proposed also, according to a socio-political approach based on the social and political relations that Calakmul maintained with other political entities of diverse ranks derived from the obtained epigraphic evidences. (Author)

  8. Adsorption of hydrocarbons on organo-clays--implications for oil spill remediation.

    Science.gov (United States)

    Carmody, Onuma; Frost, Ray; Xi, Yunfei; Kokot, Serge

    2007-01-01

    Organo-clays synthesised by the ion exchange of sodium in Wyoming Na-montmorillonite (SWy-2-MMT) with three surfactants: (a) octadecyltrimethylammonium bromide (ODTMA), formula C(21)H(46)NBr; (b) dodecyldimethylammonium bromide (DDDMA), formula C(22)H(48)BrN; and (c) di(hydrogenated tallow)dimethylammonium chloride were tested for hydrocarbon adsorption. Using diesel, hydraulic oil, and engine oil an evaluation was made of the effectiveness of the sorbent materials for a range of hydrocarbon products that are likely to be involved in land-based oil spills. It was found that the hydrocarbon sorption capacity of the organo-clays depended upon the materials and surfactants used in the organo-clay synthesis. Greater adsorption was obtained if the surfactant contained two or more hydrocarbon long chains. Extensive utilisation of chemometrics principally with the aid of MCDM methods, produced models which consistently ranked the organo-clays well above any of the competitors including commercial benchmark materials. Thus, the use of organo-clays for cleaning up oil spills is feasible due to its many desirable properties such as high hydrocarbon sorption and retention capacities, hydrophobicity. The negative effects of the use of organo-clays for oil-spill cleanup are the cost, the biodegradability, and recyclability of the organo-clays.

  9. Organoclay hybrid materials as precursors of porous ZnO/silica-clay heterostructures for photocatalytic applications

    Directory of Open Access Journals (Sweden)

    Marwa Akkari

    2016-12-01

    Full Text Available In this study, ZnO/SiO2-clay heterostructures were successfully synthesized by a facile two-step process applied to two types of clays: montmorillonite layered silicate and sepiolite microfibrous clay mineral. In the first step, intermediate silica–organoclay hybrid heterostructures were prepared following a colloidal route based on the controlled hydrolysis of tetramethoxysilane in the presence of the starting organoclay. Later on, pre-formed ZnO nanoparticles (NP dispersed in 2-propanol were incorporated under ultrasound irradiation to the silica–organoclay hybrid heterostructures dispersed in 2-propanol, and finally, the resulting solids were calcinated to eliminate the organic matter and to produce ZnO nanoparticles (NP homogeneously assembled to the clay–SiO2 framework. In the case of montmorillonite the resulting materials were identified as delaminated clays of ZnO/SiO2-clay composition, whereas for sepiolite, the resulting heterostructure is constituted by the assembling of ZnO NP to the sepiolite–silica substrate only affecting the external surface of the clay. The structural and morphological features of the prepared heterostructures were characterized by diverse physico-chemical techniques (such as XRD, FTIR, TEM, FE-SEM. The efficiency of these new porous ZnO/SiO2-clay heterostructures as potential photocatalysts in the degradation of organic dyes and the removal of pharmaceutical drugs in water solution was tested using methylene blue and ibuprofen compounds, respectively, as model of pollutants.

  10. Determining Upper Bounds for the Clay-squirt Effect in Clay Bearing Sandstone

    DEFF Research Database (Denmark)

    Sørensen, Morten Kanne; Fabricius, Ida Lykke

    Sonic measurements of saturated bulk moduli of clay bearing sandstones show larger values than expected by Gassmann modelling from dry rock properties. This causes difficulties in extrapolation of laboratory data to different saturants or frequencies. Squirt flow from the clay phase of the rock...

  11. Illitization within bentonite engineered barrier system in clay repositories for nuclear waste and its effect on the swelling stress: a coupled THMC modeling study

    Science.gov (United States)

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

    2014-12-01

    Geological repositories for disposal of high-level nuclear waste generally rely on a multi-barrier system to isolate radioactive waste from the biosphere. An engineered barrier system (EBS), which comprises in many design concepts a bentonite backfill, is widely used. Clay formations have been considered as a host rock throughout the world. Illitization, the transformation of smectite to illite, could compromise some beneficiary features of EBS bentonite and clay host rock such as sorption and swelling capacity. It is the major determining factor to establish the maximum design temperature of the repositories because it is believed that illitization could be greatly enhanced at temperatures higher than 100 oC. However, existing experimental and modeling studies on the occurrence of illitization and related performance impacts are not conclusive, in part because the relevant couplings between the thermal, hydrological, chemical, and mechanical (THMC) processes have not been fully represented in the models. Here we present a fully coupled THMC simulation study of a generic nuclear waste repository in a clay formation with a bentonite-backfilled EBS. Two scenarios were simulated for comparison: a case in which the temperature in the bentonite near the waste canister can reach about 200 oC and a case in which the temperature in the bentonite near the waste canister peaks at about 100 oC. The model simulations demonstrate that illitization is in general more significant under higher temperature. However, the quantity of illitization is affected by many chemical factors and therefore varies a great deal. The most important chemical factors are the concentration of K in the pore water as well as the abundance and dissolution rate of K-feldspar. For the particular case and bentonite properties studied, the reduction in swelling stress as a result of chemical changes vary from 2% up to 70% depending on chemical and temperature conditions, and key mechanical parameters. The

  12. Clay particles as binder for earth buildings materials: a fresh look into rheology of dense clay suspensions

    Directory of Open Access Journals (Sweden)

    Landrou Gnanli

    2017-01-01

    Full Text Available In the ceramic industry and in many sectors, clay minerals are widely used. In earthen construction technique, clay plays a crucial role in the processing. The purpose of this research is to understand and modify the clay properties in earth material to propose an innovative strategy to develop a castable earth-based material. To do so, we focused on the modification of clay properties at fresh state with inorganic additives. As the rheological behaviour of clays is controlled by their surface charge, the addition of phosphate anion allows discussing deep the rheology of concentrated clay suspensions. We highlighted the thixotropic and shear thickening behaviour of a dispersed kaolinite clay suspensions. Indeed, by adding sodium hexametaphosphate the workability of clay paste increases and the behaviour is stable during time after a certain shear is applied. Moreover, we stress that the aging and the shift in critical strain in clay system are due to the re-arrangement of clay suspension and a decrease of deformation during time. The understanding of both effect: thixotropy and aging are crucial for better processing of clay-based material and for self-compacting clay concrete. Yet, studies need to pursue to better understand the mechanism.

  13. Clay particles as binder for earth buildings materials: a fresh look into rheology of dense clay suspensions

    Science.gov (United States)

    Landrou, Gnanli; Brumaud, Coralie; Habert, Guillaume

    2017-06-01

    In the ceramic industry and in many sectors, clay minerals are widely used. In earthen construction technique, clay plays a crucial role in the processing. The purpose of this research is to understand and modify the clay properties in earth material to propose an innovative strategy to develop a castable earth-based material. To do so, we focused on the modification of clay properties at fresh state with inorganic additives. As the rheological behaviour of clays is controlled by their surface charge, the addition of phosphate anion allows discussing deep the rheology of concentrated clay suspensions. We highlighted the thixotropic and shear thickening behaviour of a dispersed kaolinite clay suspensions. Indeed, by adding sodium hexametaphosphate the workability of clay paste increases and the behaviour is stable during time after a certain shear is applied. Moreover, we stress that the aging and the shift in critical strain in clay system are due to the re-arrangement of clay suspension and a decrease of deformation during time. The understanding of both effect: thixotropy and aging are crucial for better processing of clay-based material and for self-compacting clay concrete. Yet, studies need to pursue to better understand the mechanism.

  14. CLAY SOIL STABILISATION USING POWDERED GLASS

    OpenAIRE

    2014-01-01

    This paper assesses the stabilizing effect of powdered glass on clay soil. Broken waste glass was collected and ground into powder form suitable for addition to the clay soil in varying proportions namely 1%, 2%, 5%, 10% and 15% along with 15% cement (base) by weight of the soil sample throughout. Consequently, the moisture content, specific gravity, particle size distribution and Atterberg limits tests were carried out to classify the soil using the ASSHTO classification system. Based on the...

  15. MODEL FOR PREDICTING SHEAR STRENGTH OF SATURATED SOFT CLAY AFTER IMPACT LOADING%冲击荷载作用下饱和软粘土强度预测模型

    Institute of Scientific and Technical Information of China (English)

    白冰

    2004-01-01

    Previous studies showed that the samples of saturated soft clay undergoing several stages of impact loading and reconsolidation show obvious quasi-overconsolidation state,and have an increased shear strength. In this paper,the definition of quasi-overconsolidation ratio is given,and furthermore a model for predicting the shear strength of saturated soft clay after impact loading is suggested. In this model,the conditions of partial drainage and stages of impact are taken into account. The calculation results by the proposed model are in good accordance with test data. Besides,the effect of disturbance consolidation on the undrained shear strength by this model is discussed.

  16. Effect of initial solution pH on the degradation of Orange II using clay-based Fe nanocomposites as heterogeneous photo-Fenton catalyst.

    Science.gov (United States)

    Feng, Jiyun; Hu, Xijun; Yue, Po Lock

    2006-02-01

    Effect of initial solution pH on the discoloration and mineralization of 0.2 mM Orange II by using two clay-based Fe nanocomposites (Fe-B (Fe supported on bentonite clay) and Fe-Lap-RD (Fe supported on laponite clay)) as catalysts was studied in detail. It was found that the initial solution pH not only influences the photo-catalytic activity of Fe-B and Fe-Lap-RD but also the Fe leaching from the two catalysts. Both catalysts show the best photo-catalytic activity at an initial solution pH of 3.0, and the activity of the catalysts decreases as the initial solution pH increases. At optimal conditions, 100% discoloration and mineralization of 0.2 mM Orange II are achieved in 60 and 120 min reaction in the presence of 10 mM H2O2, 1.0 g/L Fe-B, and 1 x 8 W UVC at initial solution pH of 3.0. 100% discoloration and 90% mineralization of 0.2 mM Orange II are achieved when Fe-Lap-RD is used as catalyst under the same conditions. Both catalysts also display a reasonable good photo-catalytic activity and negligible Fe leaching at an initial solution pH of 6.6 that is very close to neutral pH. This characteristic makes it possible for the Fe-B and Fe-Lap-RD to have a long-term stability. It also becomes feasible for the photo-Fenton process to treat the original wastewater without the need to pre-adjust the solution pH.

  17. Physical and numerical modelings of lateral drag in a pipeline in very soft clay; Modelagens fisica e numerica de arraste lateral de duto em argila mole

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Jose Renato M.S.; Almeida, Maria C.F.; Almeida, Marcio S.S. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia; Borges, Ricardo G.; Amaral, Claudio S. [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil). Centro de Pesquisas

    2005-07-01

    This paper discusses some results from a joint research project undertaken by COPPE/UFRJ and CENPES/PETROBRAS about soil-structure interaction applied to thermal snaking of shallowly buried pipelines embedded in very soft clay. At this phase, the lateral soil reaction due to pipeline horizontal displacements was studied by means of physical and numerical modeling. In that way, a set of comprehensive centrifuge tests has been undertaken using a 1:30 scaled pipe dragged laterally, varying the burial depth condition. The soil used for the tests is a very soft clay sample collected at the Duque de Caxias Refinery area in Rio de Janeiro. The vertical and horizontal displacements of the pipe were imposed by computer-controlled actuators, with soil reaction forces being measured on both directions. The physical modeling results were compared with numerical simulations of the same centrifuge scenarios using the software AEEPECD, developed by PETROBRAS, showing good agreement in terms of horizontal and vertical soil reactions. (author)

  18. Ternary and quaternary nanocomposites based on polystyrene, SBS, organically modified clay and silicone-polyether;Compositos e/ou nanocompositos ternarios e quaternarios de poliestireno, SBS, argila e silicona-polieter

    Energy Technology Data Exchange (ETDEWEB)

    Kaneko, Manuela L.Q.A.; Lourenco, Emerson; Paiva, Raphael E.F.; Felisberti, Maria I.; Yoshida, Inez V.P., E-mail: valeria@iqm.unicamp.b [Universidade Estadual de Campinas (IQ/UNICAMP), SP (Brazil). Inst. de Quimica

    2009-07-01

    This work aims the study of toughened nanocomposites based on polystyrene (PS), poly(styrene-b-butadiene-b-styrene) (SBS), organically modified clay (C20A) and silicone-polyether, PDMS-POE. The intercalation of the copolymer PDMS-POE into the clay galleries increased the interlamellar distance, improving the exfoliation of the clay during the extrusion process of the materials. C20A/PDMS-POE nanocomposite, MC20A, was prepared by mechanical mixture using 1:1 wt% ratio. MC20A was incorporated into PS and PS/SBS blends using an extruder. The materials were characterized by X-ray diffraction and stress-strain mechanical tests. MC20A/PS/SBS, prepared by extrusion, showed an increase in the interlamellar distance, suggesting the intercalation of PS or SBS into the clay galleries. The PDMSPOE acted as a 'plasticizer' for PS and PS/SBS blend. However, this effect was not reverted by the clay addition. On the contrary, the 'plasticizer' effect was intensified by the clay maybe due to the slip characteristics of PDMS-POE associated with the lamella orientation. (author)

  19. Study on some rheological parameters of water and clay basis drilling fluids additivated with industrial sodium silicate; Estudo de alguns parametros reologicos de fluidos de perfuracao a base de agua e argila aditivados com silicato de sodio industrial

    Energy Technology Data Exchange (ETDEWEB)

    Amorim, Luciana Viana [Universidade Federal, Campina Grande, PB (Brazil). Engenharia de Processos]. E-mail: lucianaa@labdes.ufpb.br; Viana, Josiane Dantas; Farias, Kassie Vieira [Universidade Federal, Campina Grande, PB (Brazil). Dept. de Engenharia de Materiais]. E-mail: josianedantas@bol.com.br; kassievieira@bol.com.br; Franca, Kepler Borges; Lira, Helio de Lucena; Ferreira, Heber Carlos [Universidade Federal, Campina Grande, PB (Brazil). Dept. de Eng. Quimica]. E-mail: kepler@labdes.ufpb.br; helio@dema.ufpb.br; heber@dema.ufpb.br

    2003-07-01

    The aim of this work is to study some rheological parameters of water based oil well drilling fluids and bentonite clay from Boa Vista, PB, treated with industrial sodium silicate. It were selected there samples of natural polycationic bentonite clays and four industrial sodium bentonite clays. The natural clays were treated with concentrated Na{sub 2}CO{sub 3} solution. The drilling fluids were prepared with concentration of 4.86% w/w, according to PETROBRAS norms, and additivated with four different concentration of industrial sodium silicate. After 24 hours of cure, it were measured apparent viscosity (AV) and plastic viscosity (PV) by using a Fann 35A viscosimeter and water loss (WL) by using a Fann filter press. The results showed a change in the rheology of the drilling fluids. The drilling fluids prepared with industrialized clays showed a decrease in AV and an increase in WL. For the drilling fluids prepared with natural clays treated with Na{sub 2}CO{sub 3}, it was observed a decrease in AV and WL and an increase in PV. Also, it was observed a change in the drilling fluids state from flocculated-gel to a partially flocculated. (author)

  20. Coupled modelling (transport-reaction) of the fluid-clay interactions and their feed back on the physical properties of the bentonite engineered clay barrier system; Modelisation couplee (transport - reaction) des interactions fluides - argiles et de leurs effets en retour sur les proprietes physiques de barrieres ouvragees en bentonite

    Energy Technology Data Exchange (ETDEWEB)

    Marty, N

    2006-11-15

    The originality of this work is to process feed back effects of mineralogical and chemical modifications of clays, in storage conditions, on their physical properties and therefore on their transport characteristics (porosity, molecular diffusion, permeability). These feed back effects are modelled using the KIRMAT code (Kinetic of Reaction and MAss Transfer) developed from the kinetic code KINDIS by adding the effect of water renewal in the mineral-solution reactive cells. KIRMAT resolves mass balance equations associated with mass transport together with the geochemical reactions in a 1D approach. After 100 000 years of simulated interaction at 100 C, with the fluid of the Callovo-Oxfordian geological level (COX) and with iron provided by the steel overpack corrosion, the montmorillonite of the clay barrier is only partially transformed (into illite, chlorite, saponite...). Only outer parts of the modelled profile seem to be significantly affected by smectite dissolution processes, mainly at the interface with the geological environment. The modifications of physical properties show a closure of the porosity at the boundaries of the barrier, by creating a decrease of mass transport by molecular diffusion, essentially at the interface with the iron. Permeability laws applied to this system show a decrease of the hydraulic conductivity correlated with the porosity evolution. Near the COX, the swelling pressure of the clays from the barrier decreases. In the major part of the modelled profile, the engineered clay barrier system seems to keep its initial physical properties (porosity, molecular diffusion, permeability, swelling pressure) and functionalities. (author)

  1. Clay and concrete brick

    CSIR Research Space (South Africa)

    Dlamini, MN

    2014-03-01

    Full Text Available are manufactured from raw clay as their primary ingredient. However concrete brick has also become a favoured material in recent times. This review will adumbrate the impact of these building materials on energy use and the environment....

  2. Clay goes patchy

    NARCIS (Netherlands)

    Kegel, W.K.; Lekkerkerker, H.N.W.

    2011-01-01

    Empty liquids and equilibrium gels have so far been only theoretical possibilities, predicted for colloids with patchy interactions. But evidence of both has now been found in Laponite, a widely studied clay.

  3. Dioxins in primary kaolin and secondary kaolinitic clays.

    Science.gov (United States)

    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.

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

    Science.gov (United States)

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

    2003-04-01

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

  5. Damage-dependent bounding surface model for cyclic degradation of saturated clay%考虑循环载荷下饱和黏土软化的损伤边界面模型研究

    Institute of Scientific and Technical Information of China (English)

    胡存; 刘海笑; 黄维

    2012-01-01

    研究表明,循环载荷作用下饱和黏土将发生软化,其机制主要有两个:一是孔压的积累;二是土体原有结构的不断损伤和新结构的不断重塑.针对上述机制,基于广义各向同性硬化准则建立了考虑饱和黏土循环软化的损伤单面模型.该模型在有效应力空间中引入损伤变量,表征土体结构的损伤和重塑程度,在连续的循环加载下,损伤不断累积,边界面则随着损伤的累积不断收缩,以模拟饱和黏土刚度和强度的软化;以应力反向点作为边界面的广义各向同性硬化中心和映射法则的映射中心,灵活地选择塑性模量的插值公式以模拟塑性变形和孔压的累积以及应力-应变的滞回特性.应用该模型对不排水循环三轴试验进行模拟,并且考查了循环周次、循环应力水平和固结历史对饱和黏土循环软化特性的影响,并与相关试验比较,验证了模型的有效性.%Degradation of saturated clay during cyclic loading can be assumed to be caused mainly by two mechanisms, pore water pressure build-up and the damage and remolding of soil fabric. Based on these mechanisms, a damage-dependent bounding surface model for cyclic degradation of saturated clay is proposed using the generalized isotropic hardening rule. In the model, the degree of damage and remolding of soil during cyclic loading is quantified by introducing a damage variable and the size of the bounding surface decreases with damage accumulation to characterize progressive degradation and nonlinear behavior of the saturated clay. By taking the stress reversal point as the generalized isotropic hardening center of the bounding surface as well as the mapping origin, the forms of hardening modulus can be adopted flexibly so as to predict the accumulation of plasticity deformation and pore pressure and the hysteresis property of clay. The cyclic behaviors for undrained one-way cyclic triaxial tests are predicted by the model

  6. New ceramic membranes from calcinated clay; Nouveaux supports membranaires a base de chamotte d'argile

    Energy Technology Data Exchange (ETDEWEB)

    El Moudden, N.; El Ghazouali, A.; Rakib, S.; Sghyar, M.; Rafiq, M. [Faculte des Sciences, Lab. des Materiaux et Protection de L' environnement, Fes Atlas (Morocco); Larbot, A.; Cot, L. [Laboratoire des Materiaux et Procedes Membranaires, UMR 5635-CNRS, ENSCM UM, 34 - Montpellier (France)

    2001-04-01

    The aim of the present work is to obtain porous tubular ceramic membranes from natural material. The clay powders were calcinated in air at 900 deg C for two hours. The resulting powders mixed with certain organic additives could be extruded to fabricate a porous tubular configuration with highly uniform porous structures. The mean pore diameter, measured by mercury porosimetry, is equal to 9 {mu}m and the porosity is 38% (heat treatment at 1130 deg C for two hours). Many ceramic membrane manufactures have used this type of large-pore membrane as supports for finer-pore membranes (micro-filtration or ultrafiltration). Porous membranes possess very good mechanical strength and negligible flow resistance for the membrane/support, while containing pores which allow a high degree of permeation. (authors)

  7. Copper nanoparticles supported onto montmorillonite clays as efficient catalyst for methylene blue dye degradation

    Directory of Open Access Journals (Sweden)

    M.A. Mekewi

    2016-06-01

    Full Text Available The paper describes the production of copper nanoparticles through the reduction of copper chloride (CuCl2·2H2O by hydrazine in the aqueous cetyle trimethyl ammonium bromide (CTAB solution. The copper nanoparticles were then supported on chemically activated Montmorillonite clay (MMT. The native and modified clays as well as synthesized Cu-nanoparticle-clay were structurally and texturally characterized by XRD, FTIR, BET, SEM and TEM in addition to the estimation of exchange capacity parameters. BET surface characterization revealed a decrease in surface area of the clay support after the incorporation of Cu nanoparticles. Cu/clay was then utilized as a catalyst for the degradation of aqueous solutions containing methylene blue (MB over a wide pH range. Diverse kinetics models were employed to examine the degradation process revealing a better fit with pseudo-first-order model. The present study offers a novel modified clay based catalysts for the degradation of methylene blue dye contaminant from wastewater.

  8. Silylated pillared clay (SPILC): A novel bentonite-based inorgano-organo composite sorbent synthesized by integration of pillaring and silylation.

    Science.gov (United States)

    Zhu, Lizhong; Tian, Senlin; Zhu, Jianxi; Shi, Yao

    2007-11-01

    This research examines the feasibility of synthesizing inorgano-organo composites based on bentonite-silylated pillared interlayered clays (SPILCs) by pre-pillaring of bentonite with the Keggin ion (hydroxyaluminum polycation) and then silylating with alkylchlorosilanes. The results of organic carbon content analysis, FTIR, XRD, and DTA/TG indicated that the silyl group can be successfully grafted to the inner surface of pillared interlayered clays (PILCs) through reaction with the OH groups of the pillars and the d-spacing of synthesized PILCs and SPILCs were almost the same. SPILCs have both the higher organic carbon content relative to original bentonite and PILCs and the better surface and pore properties relative to surfactants-modified organobentonites. A comparison of the modifier demand of SPILCs and CTMAB-bentonites indicated that the silylation of PILCs was a modifier-economized process for organically modification of bentonite. The heat-resistant temperature of SPILCs, 508 degrees C for OTS-Al-PILC and 214 degrees C for TMCS-Al-PILC, are more excellent organobentonites. Unlike the partition-predominated sorption mechanisms of organobentonites, both adsorption and partition are important components of sorption mechanism of SPILCs. The VOC sorption capacity of SPILCs is approximately same with that of organobentonites and the hydrophobicity of SPILCs is superior to that of PILCs.

  9. The effects of pre-existing discontinuities on the surface expression of normal faults: Insights from wet-clay analog modeling

    Science.gov (United States)

    Bonini, Lorenzo; Basili, Roberto; Toscani, Giovanni; Burrato, Pierfrancesco; Seno, Silvio; Valensise, Gianluca

    2016-08-01

    We use wet-clay analog models to investigate how pre-existing discontinuities (i.e. structures inherited from previous tectonic phases) affect the evolution of a normal fault at the Earth's surface. To this end we first perform a series of three reference experiments driven by a 45° dipping master fault unaffected by pre-existing discontinuities to generate a mechanically isotropic learning set of models. We then replicate the experiment six times introducing a 60°-dipping precut in the clay cake, each time with a different attitude and orientation with respect to an initially-blind, 45°-dipping, master normal fault. In all experiments the precut intersects the vertical projection of the master fault halfway between the center and the right-hand lateral tip. All other conditions are identical for all seven models. By comparing the results obtained from the mechanically isotropic experiments with results from experiments with precuts we find that the surface evolution of the normal fault varies depending on the precut orientation. In most cases the parameters of newly-forming faults are strongly influenced. The largest influence is exerted by synthetic and antithetic discontinuities trending respectively at 30° and 45° from the strike of the master fault, whereas a synthetic discontinuity at 60° and an antithetic discontinuity at 30° show moderate influence. Little influence is exerted by a synthetic discontinuity at 45° and an antithetic discontinuity at 60° from the strike of the master fault. We provide a ranking chart to assess fault-to-discontinuity interactions with respect to essential surface fault descriptors, such as segmentation, vertical-displacement profile, maximum displacement, and length, often used as proxies to infer fault properties at depth. Considering a single descriptor, the amount of deviation induced by different precuts varies from case to case in a rather unpredictable fashion. Multiple observables should be taken into

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

    Science.gov (United States)

    Sarabadani, Hamid; Rayhani, Mohammad T

    2014-06-01

    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.

  11. Sorption Energy Maps of Clay Mineral Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Churakov, S.V

    2005-03-01

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

  13. STRUCTURING & RHEOLOGY OF MOLTEN POLYMER/CLAY NANOCOMPOSITES

    Institute of Scientific and Technical Information of China (English)

    Yuan-ze Xu; Yi-bin Xu

    2005-01-01

    The evolution and the origin of "solid-like state" in molten polymer/clay nanocomposites are studied. Using polypropylene/clay hybrid (PPCH) with sufficient maleic anhydride modified PP (PP-MA) as compatibilizer, well exfoliation yet solid-like state was achieved after annealing in molten state. Comprehensive linear viscoelasticity and non-linear rheological behaviors together with WAXD and TEM are studied on PPCH at various dispersion stages focusing on time,temperature and deformation dependencies of the "solid-like" state in molten nanocomposites. Based on these, it is revealed that the solid-structure is developed gradually along with annealing through the stages of inter-layer expansion by PP-MA,the diffusion and association of exfoliated silicate platelets, the formation of band/chain structure and, finally, a percolated clay associated network, which is responsible for the melt rigidity or solid-like state. The network will be broken down by melt frozen/crystallization and weakened at large shear or strong flow and, even more surprisingly, may be disrupted by using trace amount of silane coupling agent which may block the edge interaction of platelets. The solid-like structure causes characteristic non-linear rheological behaviors, e.g. residual stress after step shear, abnormal huge stress overshoots in step flows and, most remarkably, the negative first normal stress functions in steady shear or step flows. The rheological and structural arguments challenge the existing models of strengthened entangled polymer network by tethered polymer chains connecting clay particles or by chains in confined melts or frictional interaction among tactoids. A scheme of percolated networking of associated clay platelets, which may in band form of edge connecting exfoliated platelets, is suggested to explain previous experimental results.

  14. 黏土垫层水力-力学-化学耦合模型研究%Coupled hydro-mechanical-chemical model for clay liner

    Institute of Scientific and Technical Information of China (English)

    张志红; 师玉敏; 朱敏

    2016-01-01

    The interconnection among mechanical behaviors of soil, pore water flow and contaminant transportis always involved in thefields of environmental geotechnical engineering and controlling of pollution.The related problems include the construction and maintenance of urban solid waste yards,and the protectionofsoil and ground water from pollution.The consolidation deformation of soil is dividedinto twoparts: mechanical consolidationdeformationcaused by mechanical loading and chemo-osmotic consolidationdeformationcaused by chemical loading. Then, based on the generalized Darcy’s law and considering dynamicvariation of soil physicaland transport properties, the coupled hydro-mechanical-chemical model for clay liner is established through theoretical deduction. The remarkable characteristic of the model isthat itachieves a full coupling of the consolidation deformation of soil, pore fluid flow and contaminant transport processes. Furthermore, theparameters of the coupled model can also reflect the impacts of coupling effects.The finite element software COMSOL Mutiphysicsis adoptedtowork out thesolution of theproposed coupled model andverify its correctness.The numerical resultsillustrate that the established model can describethecoupledhydro-mechanical-chemicalprocess through inquiring into mechanism., Moreover,the results agree well with those of Peters and Smith.The proposedmodel can accurately reveal the spatial and temporal distribution oftheexcess pore water pressure, contaminant concentrations and evolution consolidation deformation of soil.%在城市固废堆场建造运维、污染场地土壤、地下水围封阻隔等环境岩土、污染防治领域中,均会涉及到土体力学行为、孔隙水流动以及污染物运移之间的耦合作用问题。将土体的固结变形分为由力学荷载引起的力学固结变形及由化学荷载引起的化学–渗透固结变形,引入广义达西定律,并考虑土体物理特性和输运性质的动

  15. 饱和黏土不排水抗剪强度各向异性的热力学本构模型研究%Thermodynamic constitutive model for anisotropic undrained shear strength of saturated clays

    Institute of Scientific and Technical Information of China (English)

    陈志辉; 程晓辉

    2014-01-01

    An approach is proposed for the undrained strength anisotropy of saturated clays based on a thermodynamic constitutive model, TTM (Tsinghua thermodynamic soil model). The model analyses and experiments indicate that the anisotropic consolidation or K0 consolidation can be an important cause for the strength anisotropy of geotechnical materials, and the strength anisotropy becomes more significant with the decrease of the consolidation stress ratio Kc. During the undrained loading, the direction of the principal stresses has a huge influence on the undrained strength and deformation of soils. Generally speaking, with the rotation of principal stresses from 0°to 90°, the undrained shear strength decreases while the peak strain increases. Besides, the anisotropic consolidation causes the non-coaxiality of the principal stresses and strains. Based on the proposed model, simulations and predictions are made for various test results of Kaolin clay and Boston blue clay, which indicate that TTM is able to show and predict the strength change and deformation behavior of soils under complex stress paths caused by the strength anisotropy, strain softening and rotation of direction of the principal axis of stress.%基于饱和土体TTM(Tsinghua thermodynamic soil model)热力学本构模型分析研究了饱和黏土的不排水抗剪强度各向异性问题。模型及试验研究表明:非等向或K0固结历史是引起土体强度各向异性的重要原因,固结应力比Kc越小,不排水强度各向异性越大。不排水加载过程中主应力轴的方向对土体不排水抗剪强度和变形有着重要影响。一般而言,当主应力轴方向从0°旋转到90°时,土体的不排水抗剪强度逐渐下降,峰值应变却逐渐增大。此外,非等向固结会导致土体主应力与主应变的非共轴性。利用TTM理论模型,对Kaolin Clay 和Boston Blue Clay的不同试验结果进行了模拟验证和预测。结果表明,TTM理

  16. Electrolyte low concentrations effects on the the rheology of water and bentonitic clays basis drilling fluids; Efeito de baixas concentracoes de eletrolitos na reologia de fluidos de perfuracao a base de agua e argilas bentoniticas

    Energy Technology Data Exchange (ETDEWEB)

    Amorim, Luciana Viana [Universidade Federal, Campina Grande, PB (Brazil). Engenharia de Processos]. E-mail: lucianaa@labdes.ufpb.br; Viana, Josiane Dantas; Farias, Kassie Vieira; Lira, Helio de Lucena; Ferreira, Heber Carlos [Universidade Federal, Campina Grande, PB (Brazil). Dept. de Engenharia de Materiais]. E-mail: josianedantas@bol.com.br; kassievieira@bol.com.br; helio@dema.ufpb.br; heber@dema.ufpb.br; Franca, Kepler Borges [Universidade Federal, Campina Grande, PB (Brazil). Dept. de Engenharia Quimica]. E-mail: kepler@labdes.ufpb.br

    2003-07-01

    The aim of this work is to study the effect of low electrolytes concentration on the rheology of the water based oil well drilling fluids and bentonite clays from Boa Vista, PB. It were selected seven samples of bentonite clays (four from industry and three from natural polycationic clay treated with concentrated Na{sub 2}CO{sub 3} solution). The drilling fluids were prepared with a concentration of 4.86 % w/w, according to PETROBRAS norms and treated with different CaCl{sub 2} + MgCl{sub 2} concentration. After, the drilling fluids were submitted to a cure for 24 hours and measured apparent viscosity (AV), plastic viscosity (PV) and water loss (WL). To study the effect of the electrolyte on the rheology of the dispersions it was developed a factorial design 2{sup 2} + 3 test in the central point. The results showed that the addition of CaCl{sub 2} + MgCl{sub 2} caused a degradation of the drilling fluids prepared with industrialized clays, as showed by the decrease in AV and PV and great increase in WL. Also, it was observed an increase in AV and a decrease in PV in the drilling fluids prepared with natural clays treated with Na{sub 2}CO{sub 3}, conducting a flocculated-gel state. (author)

  17. Novel organo soluble poly imides and polyimide nano composites based on 1,4-bis(4-aminophenyl)-1,3,4-oxadiaz olyl)benzene, BAOB, via BAOB-modified organo clay

    Energy Technology Data Exchange (ETDEWEB)

    Mansoori, Y.; Darvishi, K., E-mail: ya_mansoori@yahoo.com [University of Mohaghegh Ardabili, Faculty of Science, Department of Applied Chemistry, Daneshgah, Ardabil (Iran, Islamic Republic of)

    2014-10-01

    New, thermally stable poly imides (PI) containing a 1,3,4-oxadiazole ring in the polymer backbone based on 1,4-bis((4-aminophenyl)-1,3,4-oxadiaz olyl)benzene, BAOB, were synthesized. The prepared polymers were soluble in polar and aprotic solvents. The obtained results reveal that within the prepared polymers, polyimide which has been obtained from BAOB and 4,4-oxy diphthalic dianhydride, ODPA, has the most improved thermal properties. In the next part, thermally stable organophilic clay was obtained via cation exchange reaction between sodium montmorillonite (Na-MMT) and the hydrochloride salt of BAOB. Then, a series of PI/clay nano composite materials (PCNs) were synthesized from the in situ polymerization reaction of BAOB and ODPA via thermal imidization, BAOB-MMT was used as the filler at different concentrations. Intercalation of polymer chains within the organo clay galleries was confirmed by W XRD. The glass transition temperature is increased with respect to pristine PI for PCNs 1-3 wt %. At high clay loadings, the aggregation of organo clay particles results in a decrease in T{sub g}. In the Sem images of the pure polymer too many micro-cracks were observed in the background, while surface homogeneity of PCN 1 wt % is increased and micro-cracks are reduced. (Author)

  18. Modernity and putty-clay

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

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

    2017-05-01

    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.

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

    Science.gov (United States)

    Al-Jlil, Saad A.

    2017-03-01

    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.

  2. Magnificent Clay Murals

    Science.gov (United States)

    Kirker, Sara Schmickle

    2007-01-01

    Each August, third grade artists at Apple Glen Elementary in Bentonville, Arkansas, start the school year planning, creating, and exhibiting a clay relief mural. These mural projects have helped students to acquire not only art knowledge and techniques, but an even more important kind of knowledge: what it means to plan and successfully complete a…

  3. Rattles of Clay.

    Science.gov (United States)

    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)

  4. Model-based geostatistics

    CERN Document Server

    Diggle, Peter J

    2007-01-01

    Model-based geostatistics refers to the application of general statistical principles of modeling and inference to geostatistical problems. This volume provides a treatment of model-based geostatistics and emphasizes on statistical methods and applications. It also features analyses of datasets from a range of scientific contexts.

  5. Physical Properties of Latvian Clays

    OpenAIRE

    2012-01-01

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

  6. Clay Animals and Their Habitats

    Science.gov (United States)

    Adamson, Kay

    2010-01-01

    Creating clay animals and their habitats with second-grade students has long been one of the author's favorite classroom activities. Students love working with clay and they also enjoy drawing animal homes. In this article, the author describes how the students created a diorama instead of drawing their clay animal's habitat. This gave students…

  7. Prediction of the residual strength of clay using functional networks

    Institute of Scientific and Technical Information of China (English)

    S.Z. Khan; Shakti Suman; M. Pavani; S.K. Das

    2016-01-01

    Landslides are common natural hazards occurring in most parts of the world and have considerable adverse economic effects. Residual shear strength of clay is one of the most important factors in the determination of stability of slopes or landslides. This effect is more pronounced in sensitive clays which show large changes in shear strength from peak to residual states. This study analyses the prediction of the residual strength of clay based on a new prediction model, functional networks (FN) using data available in the literature. The performance of FN was compared with support vector machine (SVM) and artificial neural network (ANN) based on statistical parameters like correlation coefficient (R), Nash–Sutcliff coefficient of efficiency (E), absolute average error (AAE), maximum average error (MAE) and root mean square error (RMSE). Based on R and E parameters, FN is found to be a better prediction tool than ANN for the given data. However, the R and E values for FN are less than SVM. A prediction equation is presented that can be used by practicing geotechnical engineers. A sensitivity analysis is carried out to ascertain the importance of various inputs in the prediction of the output.

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

    Science.gov (United States)

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

    1998-09-01

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

  9. Clay membrane made of natural high plasticity clay:

    DEFF Research Database (Denmark)

    Foged, Niels; Baumann, Jens

    1999-01-01

    Leachate containment in Denmark has throughout the years been regulated by the DIF Recommendation for Sanitary Landfill Liners (DS/R4669. It states that natural clay deposits may be used as membrane material provided the membrane and drainage system contains at least 95% of all leachate created...... into account advective ion transport as well as diffusion. Clay prospecting for clays rich in smectite has revealed large deposits of Tertiary clay of very high plasticity in the area around Rødbyhavn on the Danish island of Lolland. The natural clay contains 60-75% smectite, dominantly as a sodium......-type. The clay material has been evaluated using the standardized methods related to mineralogy, classification, compaction and permeability, and initial studies of diffusion properties have been carried out. Furthermore, at a test site the construction methods for establishing a 0.15-0.3 m thick clay membrane...

  10. Performance of polymeric films based thermoplastic starch and organophilic clay; Efeito da incorporacao de argila no desempenho de filmes de amido termoplastico/PEBD

    Energy Technology Data Exchange (ETDEWEB)

    Cipriano, P.B.; Costa, A.N.M.; Araujo, S.S.; Araujo, A.R.A.; Canedo, E.L.; Carvalho, L.H., E-mail: pamufcg@gmail.co [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Dept. de Engenharia de Materiais

    2010-07-01

    The aim of this work was the development and investigation of the properties of flat films of LDPE/corn thermoplastic starch (TPS). A bentonite clay (Argel) was organophilized and characterized by XRD. This clay (1%) in both pristine and organophilic forms was added to the matrix (LDPE) and to LDPE/TPS systems with TPS contents varying from 5-20% w/w. The films manufactured (LDPE, LDPE/Clay, LDPE/TPS, LDPE/TPS/Clay) were characterized. Results indicate that water vapor permeability is dependent and increases with TPS content which was attributed to the higher affinity of water by TPS. TPS and Clay addition to LDPE led to significant changes in film properties with respect to the neat LDPE. In general,tensile and perforation forces increased with clay and TPS contents; the strength of thermo sealed films lowered with natural clay addition and increased with TPS and organoclay incorporation and, in general, dynamic friction coefficient decrease with organoclay and TPS addition. Best overall properties were obtained for the systems containing the organoclay and optimal properties were achieved for the 5%TPS10 LDPE1% ANO system. (author)

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

    Indian Academy of Sciences (India)

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

    2015-04-01

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

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

    Science.gov (United States)

    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.

  13. Semianalytical Solutions for Transport in Aquifer and Fractured Clay Matrix System

    Science.gov (United States)

    A three-dimensional mathematical model that describes transport of contaminant in a horizontal aquifer with simultaneous diffusion into a fractured clay formation is proposed. A group of analytical solutions is derived based on specific initial and boundary conditions as well as ...

  14. Experimental Study on Unconfined Compressive Strength of Basalt Fiber Reinforced Clay Soil

    Directory of Open Access Journals (Sweden)

    Lei Gao

    2015-01-01

    Full Text Available In order to study the mechanism and effect of basalt fiber reinforced clay soil, a series of unconfined compressive strength tests conducted on clay soil reinforced with basalt fiber have been performed under the condition of optimum water content and maximum dry density. Both the content and length of basalt fiber are considered in this paper. When the effect of content is studied, the 12 mm long fibers are dispersed into clay soil at different contents of 0.05%, 0.1%, 0.15%, 0.20%, 0.25%, 0.30%, and 0.35%. When the effect of length is researched, different lengths of basalt fibers with 4 mm, 8 mm, 12 mm, and 15 mm are put into soil at the same content of 0.05%. Experimental results show that basalt fiber can effectively improve the UCS of clay soil. And the best content and length are 0.25% and 12 mm, respectively. The results also show that the basalt fiber reinforced clay soil has the “poststrong” characteristic. About the reinforcement mechanism, the fiber and soil column-net model is proposed in this paper. Based on this model and SEM images, the effect of fiber content and length is related to the change of fiber-soil column and formation of effective fiber-soil net.

  15. Cementitious Near-Field Sorption Data Base for Performance Assessment of an ILW Repository in Opalinus Clay

    Energy Technology Data Exchange (ETDEWEB)

    Wieland, E.; Van Loon, L. R

    2003-08-01

    The present report describes a cement sorption database (SDB) for the safety-relevant radionuclides to be disposed of in the planned Swiss repository for long-lived intermediate-level radioactive wastes (ILW). This report is an update on earlier SDBs, which were compiled for the cementitious near field of a repository for low- and intermediate-level radioactive wastes (L/ILW) by BRADBURY + SAROTT (1995) and BRADBURY + VAN LOON (1998). The radionuclide inventories are determined by the waste streams to be disposed of in the ILW repository. A list of the safety-relevant radionuclides was provided based on the currently available information on ILW inventories. The compositions of the cement porewaters in the near fields of the L/ILW and ILW repositories, which had been calculated using well-established codes for modelling cement degradation, were compared to identify any differences in the near-field conditions and to assess their influence on radionuclide sorption. Sorption values were selected based on the previously reported SDBs for the near field of the L/ILW repository. Sorption values were revised if new information and/or data were available which allowed changes to or re-appraisals of the data to be made. The sorption values recommended in this report were either selected on the basis of data from in-house experimental studies or from literature data. For some key radioelements, i.e., Cs(l), Sr(II), Ni(II), Eu(lll), Th(IV) and Sn(IV), new data were available from in-house measurements. These elements had been selected for experimental studies due to their relevance to safety assessment and/or their importance as appropriate chemical analogues. Degradation products of bitumen and cellulose, concrete admixtures and cement-derived near-field colloids were taken into account as the main potential perturbations, which could reduce radionuclide sorption in the near field. Possible impacts of the perturbing factors on radionuclide mobility were considered and

  16. Thermostability of montmorillonitic clays

    Directory of Open Access Journals (Sweden)

    Petr Jelínek

    2014-05-01

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

  17. Thermostability of montmorillonitic clays

    Institute of Scientific and Technical Information of China (English)

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

    2014-01-01

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

  18. Calcination of kaolinite clay particles for cement production

    DEFF Research Database (Denmark)

    Gebremariam, Abraham Teklay; Yin, Chungen; Rosendahl, Lasse

    2014-01-01

    Kaolinite rich clay particles calcined under certain conditions can attain favorable pozzolanic properties and can be used to substitute part of the CO2 intensive clinker in cement production. To better guide calcination of a clay material, a transient one-dimensional single particle model...

  19. Relevance of pore fluid composition for the drained strength of clays

    Science.gov (United States)

    Spagnoli, Giovanni; Fernández-Steeger, Tomás.; Arnhardt, Christian; Stanjek, Helge; Azzam, Rafig; Feinendegen, Martin

    2010-05-01

    Classical soil mechanics based on the effective stress concept with water as second phase does not apply anymore for fine-grained materials. Since clays particles are per definition colloidal in size, their properties are determined and dominated by their large surface area and hence, by their surface forces. Therefore, other mechanism plays a role. Geotechnical properties of soils with different pore fluid are especially important for clays used in hydraulic barriers for landfills. Also in the petroleum engineering or in tunnelling engineering the mechanical properties of clays with different pore fluids could be very useful. Since for clays physical and chemical interactions are decisive, the pure mechanical model (e.g. shearing and contact among the particles) is coupled by other forces, typical for colloidal sized materials. If the diffuse double layer develops from the surface of the clay particles, the interactions of the layers should develop a repulsion. That would resist part of the normal stress and producing no shearing resistance. However, the clays show different properties, dependent on their mineralogy, which complicates their behaviour. Several drained shear stress with shear box have been performed on pure Kaolinite, Illite, Na-Smectite and Ca-smectite. Since the shear behaviour of clays is also controlled by chemical interactions, the clays were mixed with pore fluids with different dielectric constant (water, ethanol), electrolyte concentration (NaCl and CaCl2) and pH (ranging from 3 to 8). Different consolidation pressures (from 15 kPa to 400 kPa) have been used in order to better understand the influence of the pore fluids on the drained cohesion (c') and on friction angle (φ'). The materials were mixed with different consistency to form a paste. The consistency ranges from 0.65 to 0.85. The results show how the sensitive the clays to different pore fluids are. Besides, Kaolinite and Illite shows a shearing behaviour almost entirely controlled

  20. Toxicity assessment of organomodified clays used in food contact materials on human target cell lines

    NARCIS (Netherlands)

    Houtman, J.; Maisanaba, S.; Puerto, M.; Gutierrez-Praena, D.; Jorda, M.; Aucejo, S.; Jos, A.

    2014-01-01

    Nowadays, the incorporation of organomodified clays based on montmorillonite into polymers intended for packaging industry is a reality. The final result is a polymer nanocomposite with enhanced barrier properties. Different organomodified clays are already commercially available and others new ones

  1. Measurement and conceptual modelling of herbicide transport to field drains in a heavy clay soil with implications for catchment-scale water quality management.

    Science.gov (United States)

    Tediosi, A; Whelan, M J; Rushton, K R; Thompson, T R E; Gandolfi, C; Pullan, S P

    2012-11-01

    Propyzamide and carbetamide are essential for blackgrass control in oilseed rape production. However, both of these compounds can contaminate surface waters and pose compliance problems for water utilities. The transport of propyzamide and carbetamide to an instrumented field drain in a small clay headwater tributary of the Upper Cherwell catchment was monitored over a winter season. Despite having very different sorption and dissipation properties, both herbicides were transported rapidly to the drain outlet in the first storm event after application, although carbetamide was leached more readily than propyzamide. A simple conceptual model was constructed to represent solute displacement from mobile pore water and preferential flow to drains. The model was able to reproduce the timing and magnitude of herbicide losses well, lending support to its conceptual basis. Measured losses in drainflow in the month following application were 1.1 and 8.1%, respectively, for propyzamide and carbetamide. Differences were due to a combination of differences in herbicide mobility and due to the fact that the monitoring period for carbetamide was hydrologically more active. For both compounds, losses were greater than those typically reported elsewhere for other herbicides. The data suggest that drainflow is the dominant pathway for the transfer of these herbicides to the catchment outlet, where water is abstracted for municipal supply. This imposes considerable constraints on the management options available to reduce surface water concentrations of herbicides in this catchment.

  2. Quick clay and landslides of clayey soils.

    Science.gov (United States)

    Khaldoun, Asmae; Moller, Peder; Fall, Abdoulaye; Wegdam, Gerard; De Leeuw, Bert; Méheust, Yves; Otto Fossum, Jon; Bonn, Daniel

    2009-10-30

    We study the rheology of quick clay, an unstable soil responsible for many landslides. We show that above a critical stress the material starts flowing abruptly with a very large viscosity decrease caused by the flow. This leads to avalanche behavior that accounts for the instability of quick clay soils. Reproducing landslides on a small scale in the laboratory shows that an additional factor that determines the violence of the slides is the inhomogeneity of the flow. We propose a simple yield stress model capable of reproducing the laboratory landslide data, allowing us to relate landslides to the measured rheology.

  3. A possible role of fluctuating clay-water systems in the production of ordered prebiotic oligomers

    Science.gov (United States)

    Lahav, N.; White, D. H.

    1980-01-01

    A model is proposed for the intermediate stages of prebiotic evolution, based on the characteristics of the adsorption and condensation of amino acids and nucleotides on the surface area of clay minerals in a fluctuating environment. Template replication and translation of adsorbed oligonucleotides and catalytic effects by peptide products on further condensation are proposed, due to specific properties of hypohydrous clay surfaces as well as the biomolecules themselves. Experimental evidence supports some of the proposed interactions, and all of them can be tested experimentally.

  4. A Study of Clay-Epoxy Nanocomposites Consisting of Unmodified Clay and Organo Clay

    Directory of Open Access Journals (Sweden)

    Graham Edward

    2006-04-01

    Full Text Available Clay-epoxy nanocomposites were synthesized from DGEBA resin and montmorillonite clay with an in-situ polymerization. One type of untreated clay and two types of organo clay were used to produce the nanocompsoites. The aims of this study were to examine the nanocomposite structure using different tools and to compare the results between the unmodified clay and modified clays as nanofillers. Although diffractogram in reflection mode did not show any apparent peak of both types of materials, the transmitted XRD (X-Ray Difraction graphs, DSC (Differential Scanning Calorimeter analysis and TEM (Transmission Electron Microscope images revealed that the modified clay-epoxy and unmodified clay-epoxy provides different results. Interestingly, the micrographs showed that some of the modified clay layers possessed non-exfoliated layers in the modified clay-epoxy nanocomposites. Clay aggregates and a hackle pattern were found from E-SEM images for both types of nanocomposite materials. It is shown that different tools should be used to determine the nanocomposite structure.

  5. Water drilling fluids: evaluation of lubricity and clay swelling control; Fluidos de perfuracao a base de agua: avaliacao de lubricidade e controle de inchamento de argilas

    Energy Technology Data Exchange (ETDEWEB)

    Felix, Thiago de Freitas; Arruda, Jefferson Teixeira; Medeiros, Ana Catarina; Garcia, Rosangela Balaban [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil)

    2008-07-01

    During the oil well drilling, drilling fluids are used in order to transport the cuttings until the surface. This fluid is also responsible for the mechanical sustentation of the well walls, the control of undesirable production of fluids in the formation, the lubricity and the cooling of the bit. The drilling fluids based on water are extensively applied due to their lower cost, thermal stability, biodegradability, easiness of pumping and treatment, resulting in smaller environmental impacts. However, some situations, such as hydrophilic shale drilling, request the use of additives to avoid the hydration of them and, consequently, the tool imprisonment or migration (filtration) of the drilling fluids into the rock. The goal of this work was to develop and test formulations of water-base drilling fluids with high capacity of inhibition of clay swelling and lubricity, obtaining drillings with larger penetration rate and calipers without enlargements. The results showed that the appropriate combination of commonly used commercial products can promote the obtaining of fluids with equal or better performance than those used by world companies. (author)

  6. Clays in natural and engineered barriers for radioactive waste confinement

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-07-01

    Andra organised an International Symposium on the use of Natural and Engineered Clay-based Barriers for the Containment of Radioactive Waste hold at the Congress Centre of Tours, France, in March 2005. The symposium provided an opportunity to take stock of the potential properties of the clay-based materials present in engineered or natural barriers in order to meet the containment specifications of a deep geological repository for radioactive waste. It was intended for specialists working in the various disciplines involved with clays and clay based minerals, as well as scientists from agencies and organisations dealing with investigations on the disposal of high-level and long-lived radioactive waste. The themes of the Symposium included geology, geochemistry, transfers of materials, alteration processes, geomechanics, as well as the recent developments regarding the characterisation of clays, as well as experiments in surface and underground laboratories. The symposium consisted of plenary sessions, parallel specialized sessions and poster sessions. (author)

  7. Clays on Mars: Review of chemical and mineralogical evidence

    Science.gov (United States)

    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.

  8. Estimation of anisotropy parameters for shale based on an improved rock physics model, part 1: theory

    Science.gov (United States)

    Zhang, Feng; Li, Xiang-yang; Qian, Keran

    2017-02-01

    Shale is observed to have strong transverse isotropy due to its complex intrinsic properties on a small scale. An improved rock physics model has been developed to effectively model this intrinsic anisotropy. Several effective medium theories (Backus averaging, differential effective medium theory and self-consistent approximation) are validated and used in different steps of the workflow to simulate the effects of clay minerals, crack-like pores, kerogen and their preferred orientation on the elastic anisotropy. Anisotropic solid clay is constructed by using different clay mineral constituents instead of assuming it to be an equivalent isotropic or transversely isotropic medium. We differentiate between the voids associated with clay and the voids associated with other minerals based on their varied geometries and their different contributions to the anisotropy. The degree of alignment of clay particles, interconnected pore fluid and kerogen has a great influence on the elastic properties of shale. Therefore, in addition to the pore aspect ratio (asp), a new parameter called the lamination index (LI) related to the distribution of clay particle orientation is proposed and needs to be estimated during the modeling. We then present a practical inversion scheme to enable the prediction of anisotropy parameters for both vertical and horizontal well logs by estimating the lamination index and the pore aspect ratio simultaneously. The predicted elastic constants are demonstrated by using the published laboratory measurements of some Greenhorn shale, and they show better accuracy than the estimations in the existing literature. This model takes different rock properties into consideration and is thus generalized for shale formations from different areas. The application of this model to the well logs of some Upper Triassic shale in the Sichuan basin, and the analyzed results, are presented in part 2 of this paper.

  9. Characterization of clay from northern of Morocco for their industrial application

    Science.gov (United States)

    El Ouahabi, Meriam; Fagel, Nathalie

    2010-05-01

    Clays are a natural resource used for millennia. Currently applications such as industrial minerals are diversified. In this context, our goal is to estimate the potential of the many clay deposits in northern of Morocco. The choice of this region is justified by the particular abundance of clay deposits used to manufacture building materials (brick, ceramic and refractories) and pottery. This study focuses on the mineralogical, chemical and geotechnical characterization tests carried out on Tangier-Tetouan and Meknes clays from northern of Morocco. The suitability of raw clay material from those regions in order to produce ceramic and brick has not been tested yet. The results revealed that the studied samples are diversified, kaolinite and illite (Tetouan clay) and kaolinite and illite and smectite and vermiculite (Tangier and Meknes clay) based materials. There were no major differences in grain-size distribution, whereas Meknes clay was more plastic than Tetouan-Tangier clay. The cation exchange capacity show that Meknes and Tangier clay were more important than Tetouan clay. Specific surface area and thermal analaysis complete this caracterization. It was found that almost all technological properties of the Meknes clay deposit are led to the manufacture of ceramic floor tile, and Tetouan-Tangier clay provide opportunities to making brick and ceramic floor. The Tetouan-Tangier and Meknes clay are a potential ceramic raw material for growing Morrocan ceramic tile and brick industries.

  10. A conceptual model linking functional gene expression and reductive dechlorination rates of chlorinated ethenes in clay rich groundwater sediment

    DEFF Research Database (Denmark)

    Bælum, Jacob; Chambon, Julie Claire Claudia; Scheutz, Charlotte

    2013-01-01

    We used current knowledge of cellular processes involved in reductive dechlorination to develop a conceptual model to describe the regulatory system of dechlorination at the cell level; the model links bacterial growth and substrate consumption to the abundance of messenger RNA of functional gene...

  11. Mud peeling and horizontal crack formation in drying clays

    KAUST Repository

    Style, Robert W.

    2011-03-01

    Mud peeling is a common phenomenon whereby horizontal cracks propagate parallel to the surface of a drying clay. Differential stresses then cause the layer of clay above the crack to curl up to form a mud peel. By treating the clay as a poroelastic solid, we analyze the peeling phenomenon and show that it is caused by the gradient in tensile stress at the surface of the clay, analogously to the spalling of thermoelastic materials. For a constant water evaporation rate at the clay surface we derive equations for the depth of peeling and the time of peeling as functions of the evaporation rate. Our model predicts a simple relationship between the radius of curvature of a mud peel and the depth of peeling. The model predictions are in agreement with the available experimental data. Copyright 2011 by the American Geophysical Union.

  12. NEXAFS microscopy studies of the association of hydrocarbon thin films with fine clay particles

    Energy Technology Data Exchange (ETDEWEB)

    Covelli, Danielle [Department of Chemistry, University of Saskatchewan, Saskatoon, SK, S7N 5C9 (Canada); Hernandez-Cruz, Daniel [Brockhouse Institute for Material Research, McMaster University, Hamilton, ON, L8S 4M1 (Canada); Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Haines, Brian M. [Department of Chemistry, University of Saskatchewan, Saskatoon, SK, S7N 5C9 (Canada); Munoz, Vincente; Omotoso, Oladipo; Mikula, Randy [CANMET Energy Technology Centre Natural Resources Canada, Devon, AB, T9G 1A8 (Canada); Urquhart, Stephen [Department of Chemistry, University of Saskatchewan, Saskatoon, SK, S7N 5C9 (Canada)], E-mail: stephen.urquhart@usask.ca

    2009-06-15

    The nature of organic species associated with clay minerals plays a significant role in several processes, from hydrocarbon recovery in oil sands to contaminated soil remediation and water treatment. In this work, we address the use of scanning transmission X-ray microscopy (STXM) in conjunction with near edge X-ray absorption fine structure (NEXAFS) spectroscopy to study the microstructure and chemistry of organic-clay associations in situ. A model system based on methylene blue and illite is used to explore the sensitivity of NEXAFS microscopy to these interactions, and to identify and resolve experimental challenges in these measurements. We find that sample contamination from X-ray induced photodeposition is a significant problem in STXM microscopy, but also that this problem can be substantially reduced with a liquid nitrogen cooled anticontaminator. With appropriate sample preparation and experimental procedures, we find that STXM microscopy is sensitive to thin carbon adsorbates on clay surfaces.

  13. Modelling of the mechanical behaviour and damage of clay-stones: application to the East argillite; Modelisation du comportement mecanique des argiles raides avec prise en compte de l'endommagement: application aux argilites de l'Est

    Energy Technology Data Exchange (ETDEWEB)

    Aublive-Conil, N

    2003-03-15

    The storage in deep geological formation is one of the solutions retained by France for the management of highly long life radioactive waste. The retained host rock is a clay-stone named East argillite located in the departments of Meuse and Haute-Marne. A thermodynamic formulation is used to propose a rheological model, which reproduces the mechanical behavior of clay-stones. Initially, an anisotropic damage plastic model was formulated in order to describe material degradations. Then, the damage plastic model is reformulated in order to taken into account the damage influence on the hydraulic behavior of porous material. The numerical simulations correctly reproduce the mechanical behavior of East Argillites but also the anisotropy of the hydraulic behavior introduced by the damage effect. (author)

  14. Impact of consolidation pressure on contaminant migration in clay liner

    Directory of Open Access Journals (Sweden)

    Zhi-hong ZHANG

    2013-07-01

    Full Text Available Consolidation deformation occurs in clay liners under the self-weight of wastes at a simple garbage dump or dredged sediment dump, which leads to a decrease in the porosity. However, the migration of contaminants in clay liners is influenced by the porosity. Thus, the impact of consolidation deformation of clay liners on the migration of contaminants cannot be ignored. Based on Biot’s consolidation theory, the contaminant migration theory, and consideration of the three kinds of migration mechanisms of convection, diffusion, and adsorption, a one-dimensional migration model of contaminants in deforming porous media was established, and the finite difference method was adopted to obtain the numerical solutions for an established initial-boundary value problem. The impact of consolidation pressure on the migration law of a contaminant was studied. The results show that, regardless of adsorption modes, different consolidation pressures have similar impacts on the migration law of the contaminant. Namely, over a certain migration time, the greater the consolidation pressure is, the smaller the migration depth of the contaminant. The results also show that, while the migration time increases, the impact of a certain increment of consolidation pressure on the variation of contaminant concentration with the depth increases gradually and, while the migration depth increases, the impact of a certain increment of consolidation pressure on the variation of the contaminant concentration with time increases gradually.

  15. NOAA Office for Coastal Management Coastal Inundation Digital Elevation Model: Jacksonville (FL) WFO - Duval, Clay, and Nassau Counties

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This digital elevation model (DEM) is a part of a series of DEMs produced for the National Oceanic and Atmospheric Administration Office for Coastal Management's Sea...

  16. A new type of bounding surface plasticity model for cyclic behavior of saturated clay%适用于饱和黏土循环动力分析的新型边界面塑性模型

    Institute of Scientific and Technical Information of China (English)

    胡存; 刘海笑

    2011-01-01

    In order to precisely evaluate the response of embedded offshore structures in a complicated ocean environment, it is essential to develop more simple and more accurate soil models under cyclic loading. Based on the generalized isotropic hardening rule, a new type of bounding surface plasticity model is herein proposed which is capable of modeling the undrained saturated clay behavior under cyclic loading. According to the movement of the hardening center, the new bounding surface plasticity model for predicting the evolvement of clay anisotropy can not only be adapted to the hardening isotropically but also kinematically. Meanwhile, virgin loading, unloading and reloading processes are treated differently when calculating the hardening modulus to predict the accumulation of permanent strain and pore pressure. The hardening center is taken as the mapping origin in the radial mapping rule to simulate the hysteresis property of clay under cyclic loading. The results of model simulations show an encouraging agreement with the experi- mental data from triaxial tests subjected to both short-term high stress level and long-term low stress level cyclic loading conditions.%为了合理评估嵌入式海洋工程结构在海洋环境中的动力响应和工作性能,有必要建立一种形式简单且能真实模拟饱和土体复杂动力特性的本构模型。本文基于广义各向同性硬化准则提出了适用于描述循环荷载作用下饱和黏土复杂动力特性的新型边界面塑性模型。模型引入广义各向同性硬化中心,实现边界面的等向硬化和运动硬化,以反映循环荷载作用下饱和黏土各向异性的演化。同时,土体的连续循环加载过程被分为三类加载事件:初始加载、卸载和再加载事件,采用不同的插值公式计算其塑性模量,以模拟循环塑性应变和孔压的累积;以该硬化中心作为映射中心,从而体现土体在卸载过程中产生的塑性变形

  17. Discoloration and mineralization of Orange II by using a bentonite clay-based Fe nanocomposite film as a heterogeneous photo-Fenton catalyst.

    Science.gov (United States)

    Feng, Jiyun; Hu, Xijun; Yue, Po Lock

    2005-01-01

    Discoloration and mineralization of an azo dye Orange II was conducted by using a bentonite clay-based Fe nanocomposite (Fe-B) film as a heterogeneous photo-Fenton catalyst in the presence of UVC light and H(2)O(2). Under optimal conditions (pH=3.0, 10 mM H(2)O(2), and 1 x 8W UVC), 100% discoloration and 50-60% TOC removal of 0.2 mM Orange II can be achieved in 90 and 120 min, respectively. The mineralization kinetics of 0.2 mM Orange II is much slower than the corresponding discoloration kinetics. Under the same conditions, the Fe leaching from the Fe-B-coated catalyst film is very low. The Fe-B-coated catalyst film could be used in the pre-treatment of wastewater for an integrated system consisting of a photochemical reactor and a biological reactor. Multi-run experimental results reveal that the Fe-B-coated catalyst film could have a long-term stability for the discoloration and mineralization of Orange II. A comparison between the performance of the Fe-B-coated catalyst film and a suspended Fe-B catalyst in the discoloration and mineralization of Orange II was also discussed.

  18. Characterization of groundwater dynamics in landslides in varved clays

    Directory of Open Access Journals (Sweden)

    J. E. van der Spek

    2013-01-01

    Full Text Available Groundwater dynamics may play a significant role in landslides. A detailed model is developed of the groundwater dynamics in landslides in varved clays in the Trièves area in the French Alps. The varved clays consist of a sequence of alternating silt and clay layers, covered by a colluvium layer and cut through by fissures. The hydraulic conductivity of the clay layers is negligible compared to the silt layers. It is conceptualized that fissures form a hydraulic connection between the colluvium and the varved clays. Groundwater recharge flows through the colluvium into the fissures where water is exchanged horizontally between the fissure and the silt layers of the varved clays. Groundwater flow in the colluvium is simulated with the Boussinesq equation while flow in the silt layers of the varved clays is simulated with the Richards' equation. Longitudinal outflow from the fissure is simulated with a linear-reservoir model. Scattered data of relatively short monitoring periods is available for several landslides in the region. A good similarity between observed and simulated heads is obtained, especially when considering the lack of important physical parameters such as the fissure width and the distance between the monitoring point and the fissure. A simulation for the period 1959–2004 showed some correlation between peaks in the simulated heads and the recorded occurrence of landslides while the bottom of the varved clays remained saturated during the entire simulation period.

  19. Integration Algorithm of Bounding-surface Model for Analyzing Cyclic Behaviors of Saturated Clay%饱和粘土循环动力分析边界面模型的积分算法

    Institute of Scientific and Technical Information of China (English)

    张福征; 胡存; 刘海笑

    2012-01-01

    Based on kinematic hardening rule, the bounding-surface plasticity model can be used to predict the dynamic response of saturated clay subject to cyclic loading. The numerical integration of the model is regarded as the means to evaluate offshore marine structures ,such as large-diameter cylindrical structure, the guarantee of bearing performance and dynamic response in the marine environment. The stress conversion method based on SMP rule is adopted to build a bounding-surface model which consider the tensile properties of the soil. Based on generalized trapezoidal rule, the integration algorithm of bounding-surface model is put forward to simulate the tri-axial tensile test and dynamic tri-axial test for the saturated soil. The simulation result basically accords with the geotechnical testing data.%基于运动硬化准则的新型边界面塑性模型,能够预测循环载荷作用下饱和粘土的动力响应,该模型的数值积分格式是合理评估海洋环境下大圆筒结构等近海工程结构承载性能和动力响应的保证.采用基于SMP准则的变换应力法,建立能考虑土体拉伸特性的边界面模型,根据广义梯形法则提出该模型的积分算法,模拟饱和粘土的三轴拉伸试验和动三轴试验,数值结果与土工试验数据吻合较好.

  20. Web Based VRML Modelling

    NARCIS (Netherlands)

    Kiss, S.

    2001-01-01

    Presents a method to connect VRML (Virtual Reality Modeling Language) and Java components in a Web page using EAI (External Authoring Interface), which makes it possible to interactively generate and edit VRML meshes. The meshes used are based on regular grids, to provide an interaction and modeling

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

    Science.gov (United States)

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

    2015-01-01

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

  2. Dielectric relaxation behavior of Callovo-Oxfordian clay rock: A hydraulic-mechanical-electromagnetic coupling approach

    Science.gov (United States)

    Wagner, Norman; Bore, Thierry; Robinet, Jean-Charles; Coelho, Daniel; Taillade, Frederic; Delepine-Lesoille, Sylvie

    2013-09-01

    Water content is a key parameter to monitor in nuclear waste repositories such as the planed underground repository in Bure, France, in the Callovo-Oxfordian (COx) clay formation. High-frequency electromagnetic (HF-EM) measurement techniques, i.e., time or frequency domain reflectometry, offer useful tools for quantitative estimation of water content in porous media. However, despite the efficiency of HF-EM methods, the relationship between water content and dielectric material properties needs to be characterized. Moreover, the high amount of swelling clay in the COx clay leads to dielectric relaxation effects which induce strong dispersion coupled with high absorption of EM waves. Against this background, the dielectric relaxation behavior of the clay rock was studied at frequencies from 1 MHz to 10 GHz with network analyzer technique in combination with coaxial transmission line cells. For this purpose, undisturbed and disturbed clay rock samples were conditioned to achieve a water saturation range from 0.16 to nearly saturation. The relaxation behavior was quantified based on a generalized fractional relaxation model under consideration of an apparent direct current conductivity assuming three relaxation processes: a high-frequency water process and two interface processes which are related to interactions between the aqueous pore solution and mineral particles (adsorbed/hydrated water relaxation, counter ion relaxation and Maxwell-Wagner effects). The frequency-dependent HF-EM properties were further modeled based on a novel hydraulic-mechanical-electromagnetic coupling approach developed for soils. The results show the potential of HF-EM techniques for quantitative monitoring of the hydraulic state in underground repositories in clay formations.

  3. Desorption of toluene from modified clays using supercritical carbon dioxide

    Directory of Open Access Journals (Sweden)

    Carneiro D. G. P.

    2004-01-01

    Full Text Available The main objective of this work is to study the regeneration capacity of modified clays using supercritical fluid. These modified clays are used as organic compound adsorvents. The experimental step was done using a packed column with the clay contaminated by toluene. The results obtained showed the influence of the density of the supercritical CO2 and of the organic modifier in the desorption process. These data were modeled with first- and second-order models. Better results were obtained using the second-order model. This study makes possible the scale-up of the desorption process for regeneration of solid matrices using supercritical fluids.

  4. Satellite based radar interferometry to estimate large-scale soil water depletion from clay shrinkage: possibilities and limitations

    NARCIS (Netherlands)

    Brake, te B.; Hanssen, R.F.; Ploeg, van der M.J.; Rooij, de G.H.

    2013-01-01

    Satellite-based radar interferometry is a technique capable of measuring small surface elevation changes at large scales and with a high resolution. In vadose zone hydrology, it has been recognized for a long time that surface elevation changes due to swell and shrinkage of clayey soils can serve as

  5. Satellite based radar interferometry to estimate large-scale soil water depletion from clay shrinkage: possibilities and limitations

    NARCIS (Netherlands)

    Brake, te B.; Hanssen, R.F.; Ploeg, van der M.J.; Rooij, de G.H.

    2013-01-01

    Satellite-based radar interferometry is a technique capable of measuring small surface elevation changes at large scales and with a high resolution. In vadose zone hydrology, it has been recognized for a long time that surface elevation changes due to swell and shrinkage of clayey soils can serve as

  6. Clay particle retention in small constructed wetlands.

    Science.gov (United States)

    Braskerud, B C

    2003-09-01

    Constructed wetlands (CWs) can be used to mitigate non-point source pollution from arable fields. Previous investigations have shown that the relative soil particle retention in small CWs increases when hydraulic load increases. This paper investigates why this phenomenon occurs, even though common retention models predict the opposite, by studying clay and silt particle retention in two Norwegian CWs. Retention was measured with water flow proportional sampling systems in the inlet and outlet of the wetlands, and the texture of the suspended solids was analyzed. The surface area of the CWs was small compared to the watershed area (approximately 0.07%), giving high average hydraulic loads (1.1 and 2.0 md(-1)). One of the watersheds included only old arable land, whereas the other included areas with disturbed topsoil after artificial land leveling. Clay particle retention was 57% for the CW in the first watershed, and 22% for the CW in the disturbed watershed. The different behavior of the wetlands could be due to differences in aggregate size and stability of the particles entering the wetlands. Results showed that increased hydraulic loads did affect CW retention negatively. However, as runoff increased, soil particles/aggregates with higher sedimentation velocities entered the CWs (e.g., the clay particles behaved as silt particles). Hence, clay particle settling velocity is not constant as assumed in many prediction models. The net result was increased retention.

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

    Science.gov (United States)

    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 ( clay addition level compared with no clay addition, but this difference was not significant ( = 0.17). Nitrous oxide emissions were significantly lower (×3; 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.

  8. 80 FR 65469 - NESHAP for Brick and Structural Clay Products Manufacturing; and NESHAP for Clay Ceramics...

    Science.gov (United States)

    2015-10-26

    ... Clay Products Manufacturing; and NESHAP for Clay Ceramics Manufacturing; Final Rule #0;#0;Federal...; and NESHAP for Clay Ceramics Manufacturing AGENCY: Environmental Protection Agency (EPA). ACTION... NESHAP for Clay Ceramics Manufacturing. All major sources in these categories must meet...

  9. Defluoridation of drinking water using Al3+-modified bentonite clay: Optimization of fluoride adsorption conditions

    CSIR Research Space (South Africa)

    Vhahangwele, M

    2014-11-01

    Full Text Available Al(sup3+)-bentonite clay (Alum-bent) was prepared by ion exchange of base cations on the matrices of bentonite clay. Intercalation of bentonite clay with Al(sup3+) was performed in batch experiments. Parameters optimized include time, dosage, and Al...

  10. Thermal-Mechanical Properties of Polyurethane-Clay Shape Memory Polymer Nanocomposites

    NARCIS (Netherlands)

    Xu, Bin; Fu, Yong Qing; Huang, Wei Min; Pei, Yu Tao; Chen, Zhenguo; Hosson, Jeff T.M. De; Kraft, Arno; Reuben, R.L.

    2010-01-01

    Shape memory nanocomposites of polyurethane (PU)-clay were fabricated by melt mixing of PU and nano-clay. Based on nano-indentation and microhardness tests, the strength of the nanocomposites increased dramatically as a function of clay content, which is attributed to the enhanced nanoclay-polymer i

  11. Surface Properties of the Microgels Based on N-isopropylacrylamide and Tert-butyl Acrylate by Using N, N'-methylene-bis(acrylamide) and Clay as Cross-linker

    Institute of Scientific and Technical Information of China (English)

    ZHANG Qing-song; LU Ping; ZHA Liu-sheng; MA Jing-hong; LIANG Bo-run

    2006-01-01

    Adopting N, N'-methylene-bis (acrylamide) (MBA) and inorganic clay (hectorite) as chemical and physical crosslinking agent, respectively, a series temperature sensitive microgels, based on N-isopropylacrylamide (NIPAM) as a main monomer and tert-butyl acrylate (tBA) as a comonomer were synthesized by surfactant-free emulsion polymerization (SFEP). The microgel particle size and morphology was investigated by means of Atomic Force Microscope (AFM). The surface tension of latex particles was measured by OCA 40 Micro Video based contact angle measuring device. The results showed that the particle size of the microgels with clay as cross-linker was smaller than that using MBA as chemical cross-linker, but exterior morphology of physical microgels is not as clean and neat as chemical microgels. In general, surface tension decreases with increasing hydrophobic tBA content. These smart microgels varied with temperature have the potential applications in the field of drug delivery and intelligent gel fiber.

  12. Thermal-Mechanical Properties of Polyurethane-Clay Shape Memory Polymer Nanocomposites

    Directory of Open Access Journals (Sweden)

    Arno Kraft

    2010-04-01

    Full Text Available Shape memory nanocomposites of polyurethane (PU-clay were fabricated by melt mixing of PU and nano-clay. Based on nano-indentation and microhardness tests, the strength of the nanocomposites increased dramatically as a function of clay content, which is attributed to the enhanced nanoclay–polymer interactions. Thermal mechanical experiments demonstrated good mechanical and shape memory effects of the nanocomposites. Full shape memory recovery was displayed by both the pure PU and PU-clay nanocomposites.

  13. Validation of a kinetic-diffusive model to characterize pozzolanic reaction kinetics in sugar cane straw-clay ash/lime systems

    Directory of Open Access Journals (Sweden)

    Villar-Cociña, E.

    2005-06-01

    Full Text Available A kinetic-diffusive model proposed by the authors in previous papers to describe pozzolanic reaction kinetics in sugar cane straw-clay ash (SCSCA/calcium hydroxide (CH systems is validated in this study. Two different methods (direct and indirect for determining pozzolanic activity were applied and their effect on pozzolanic reaction rate kinetic constants evaluated. Determined by fitting a model to the data, these constants are used to quantitatively characterize pozzolanic activity. The values of the kinetic constants calculated with the model were similar for the two methods. Classic kinetic models, such as the Jander, modified Jander and Zhuravlev models, were also applied to the system studied and the results were compared to the figures calculated with the model proposed. The kinetic-diffusive approach proposed was found to be valid regardless of the method for determining pozzolanic activity used, and to be the most suitable model for describing pozzolanic reaction kinetics in the SCSCA/lime system.

    Se valida la aplicación de un modelo cinético-difusivo propuesto por los autores en trabajos anteriores para describir la cinética de reacción puzolánica en sistemas ceniza de paja de caña-arcilla (CPCAñúdróxido de calcio (CH. Se aplican 2 métodos diferentes de actividad puzolánica (directo e indirecto y se valora el efecto que pudieran tener los mismos sobre las constantes cinéticas de velocidad de reacción de la reacción puzolánica. Estas constantes cinéticas son determinadas en el proceso de ajuste del modelo y permiten caracterizar cuantitativamente la actividad puzolánica. Los resultados muestran la similitud de las constantes cinéticas de velocidad de reacción calculadas, aplicando el modelo a los resultados experimentales obtenidos por ambos métodos. Además, fueron aplicados al sistema estudiado modelos cinéticos el chicos como: modelo de Jander, modelo de Jander Modificado y el modelo de Zhuravlev y

  14. Sedimentology, diagenesis, clay mineralogy and sequential analysis model of Upper Paleocene evaporite-carbonate ramp succession from Tamerza area (Gafsa Basin: Southern Tunisia)

    Science.gov (United States)

    Messadi, Abdel Majid; Mardassi, Besma; Ouali, Jamel Abdennaceur; Touir, Jamel

    2016-06-01

    Integrated sedimentological studies, diagenesis, sequential analysis and clay mineralogy on the Upper Paleocene rocks in Tamerza area provide important information on the reconstruction of the depositional basin, cyclicity, and paleoclimatic contexts. Facies analysis and petrographic studies have led to the recognition of nine facies that were deposited in three facies belts: Sebkha, inner ramp and outer ramp summarized in a carbonate ramp model: Homoclinal ramp under an arid climate. The upward and lateral changes in thickness and composition show a general regressive trend that records a transition from an outer ramp to Sebkha, creating different types of confinement. The facies stacking patterns constitute several kinds of meter-scale, shallowing-upward cycles. Nine different types of depositional cycles and several models of Sebkha sequences were defined. These different types of facies, characterized within the Thelja Formation, compose seven depositional sequences, mainly made of carbonates, marls and evaporates. Detailed multi approach analysis provides important information on evaporitic sequence stratigraphy. In carbonates beds, the diagenetic analysis provides an overview and chronology of diagenetic processes. A particular attention was paid to early stage cementation which enables us to characterize better the depositional environments. In addition to cementation, other features define the diagenetic history. X-ray diffraction reveals the presence of smectite suggesting an arid climate. Moreover, the clinoptilolite and the frequency of primary dolomite indicate different degrees of confinement. The seven depositional sequences showing a hierarchical organization of many cycles, as described above, suggested that eustatic sea level oscillations caused by cyclic perturbations of the Earth's orbit play a fundamental role in determining the formation of hierarchical cyclic rhythmicity.

  15. Dual phase polymer gel electrolyte based on non-woven poly(vinylidenefluoride-co-hexafluoropropylene)–layered clay nanocomposite fibrous membranes for lithium ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Shubha, Nageswaran [School of Materials Science and Engineering, Nanyang Technological University, Block N4.1, 50 Nanyang Avenue, Singapore 639798 (Singapore); Prasanth, Raghavan [School of Materials Science and Engineering, Nanyang Technological University, Block N4.1, 50 Nanyang Avenue, Singapore 639798 (Singapore); Energy Research Institute - NTU (ERI-N) Research Techno Plaza, 50 Nanyang Drive, Singapore 637553 (Singapore); TUM-CREATE Center for Electromobility, Nanyang Technological University, Singapore 637553 (Singapore); Hoon, Hng Huey [School of Materials Science and Engineering, Nanyang Technological University, Block N4.1, 50 Nanyang Avenue, Singapore 639798 (Singapore); Srinivasan, Madhavi, E-mail: madhavi@ntu.edu.sg [School of Materials Science and Engineering, Nanyang Technological University, Block N4.1, 50 Nanyang Avenue, Singapore 639798 (Singapore); Energy Research Institute - NTU (ERI-N) Research Techno Plaza, 50 Nanyang Drive, Singapore 637553 (Singapore); TUM-CREATE Center for Electromobility, Nanyang Technological University, Singapore 637553 (Singapore)

    2013-02-15

    Graphical abstract: Display Omitted Highlights: ► P(VdF-co-HFP)–clay nanocomposite based electrospun membranes are prepared. ► The membranes are used as polymer gel electrolyte (PGE) in lithium ion batteries. ► The composite PGE shows ionic conductivity of 5.5 mS cm{sup −1} at room temperature. ► Li/PGE/LiFePO{sub 4} cell delivers initial discharge capacity of 160 mAh g{sup −1}. ► The use of prepared electrolyte significantly improved the cell performance. -- Abstract: A new approach for fabricating polymer gel electrolytes (PGEs) based on electrospun poly(vinylidenefluoride-co-hexafluoropropylene) (P(VdF-co-HFP)) incorporated with layered nanoclay has been employed to enhance the ionic conductivity and electrochemical properties of P(VdF-co-HFP) without compromising its mechanical strength. The effect of layered nanoclay on properties of membranes has been evaluated by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). Surface morphology of the membranes has been studied using field-emission scanning electron microscopy (FE-SEM). Polymer gel electrolytes are prepared by soaking the fibrous membrane into 1 M LiPF{sub 6} in EC/DEC. The electrochemical studies show that incorporation of layered nanoclay into the polymer matrix greatly enhanced the ionic conductivity and compatibility with lithium electrodes. The charge–discharge properties and cycling performance of Li/LiFePO{sub 4} cells comprising nanocomposite polymer gel electrolytes have been evaluated at room temperature.

  16. Boom clay borehole water, home of a diverse bacterial community

    Energy Technology Data Exchange (ETDEWEB)

    Wouters, Katinka; Moors, Hugo; Leys, Natalie [Belgian Nuclear Research Centre (SCK-CEN), Mol (Belgium)

    2013-07-01

    For over two decades, Boom Clay has been studied in the framework of geological disposal of nuclear waste thereby mainly addressing its geochemical properties. Today, also the microbiological properties and the possibility of microbes interacting with radionuclides or repository components including the waste form, in a host formation like Boom Clay are considered [2,3]. In the past, a reference composition for synthetic Boom Clay pore water (BCPW) was derived, based on interstitial water sampled from different layers within the Boom clay [1]. Similarly, the primary aim of this microbiological study was to determine the core BCPW bacterial community and identify representative water samples for future microbial directed lab experiments. In this respect, BCPW was sampled from different Boom Clay layers using the Morpheus piezometer and subsequently analysed by microscopy and molecular techniques, in search for overall shared and abundant micro-organisms. (authors)

  17. Project Opalinus clay Zuercher Weinland of Nagra. Evaluation of the geo-scientific data base and of the construction engineering aspects; Projekt Opalinuston Zuercher Weinland der Nagra. Beurteilung der erdwissenschaftlichen Datengrundlagen und der bautechnischen Machbarkeit

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-02-15

    In this report the Commission for Nuclear Waste Management (KNE) assesses the geological and engineering aspects of the project Opalinus Clay, in which Nagra demonstrates the postclosure safety of geological disposal of spent fuel (SF), vitrified high-level wastes (HLW) and intermediate-level wastes (ILW) in a repository in the Opalinus Clay of the Zuercher Weinland in northern Switzerland. After in-depth examination of the geological database, KNE concludes that the demonstration of a suitable geological site for final disposal of SF, HLW and ILW in the Opalinus Clay of the Zuercher Weinland has been achieved. The geological assumptions Nagra uses for the assessment of long-term safety are based on data that have been carefully collected and interpreted. KNE acknowledges that Nagra interpreted the geological data correctly and adequately using state-of-the-art techniques. In case of lacking information, Nagra has used conservative or worst-case assumptions. The information documented by Nagra represents a good synthesis of field, laboratory and literature data. The tectonic situation of the Zuercher Weinland was examined in great details by Nagra. In the centre of the investigated region, where the Opalinus Clay occurs at 600 to 750 meters depth, the 3D-seismic data confirm its undisturbed stratification in an area of about 15 km{sup 2}. Analysis and interpretation of the available information on the geological evolution provides no indication that erosion would expose the confining units above the Opalinus Clay within the next million years. The Opalinus Clay in the Zuercher Weinland is quite homogeneous and about 110 m thick. The properties of this rock are examined and found to be favourable for a repository. The dominance of the fine grain size and the high clay content indicate a very low hydraulic conductivity suitable for the isolation of radioactive wastes. Pore water extracted from drill-core samples is saline and has remained trapped for millions of

  18. Excavation collapse of Hangzhou subway station in soft clay and numerical investigation based on orthogonal experiment method

    Institute of Scientific and Technical Information of China (English)

    Xiao-nan GONG; Xue-chan ZHANG

    2012-01-01

    This paper studies the excavation collapse at the Xianghu subway station on Hangzhou metro line I.The objective is to present an overview of this case study and discuss the cause of the failure.Through field investigation and preliminary analysis,the reasons for the excavation collapse were the misuse of the soil parameters,over excavation,incorrect installation of steel struts,invalid monitoring data,and inadequate ground improvement.Finally,a small strain constitutive model was used for further analysis.In order to estimate damage efficiently,the orthogonal array (OA) was introduced for screening the key factor in the numerical experiments.Six estimated indexes including deformations and internal forces of the excavation were taken,and the effectiveness of four factors which may cause the collapse was evaluated.Through numerical experiments and interaction analysis,it is found that the deformation and internal force can be well controlled by jet grouting of the subsoil under the final cutting surface,but increasing the improvement ratio of the jet grouting cannot help optimize the excavation behavior efficiently,and without jet grouting and the fourth level struts,the deformation and internal force of the excavation in this case will far surpass the allowable value.

  19. Ab initio molecular dynamics study of the interlayer and micropore structure of aqueous montmorillonite clays

    Science.gov (United States)

    Suter, James L.; Kabalan, Lara; Khader, Mahmoud; Coveney, Peter V.

    2015-11-01

    Ab initio molecular dynamics simulations have been performed to gain an understanding of the interfacial microscopic structure and reactivity of fully hydrated clay edges. The models studied include both micropore and interlayer water. We identify acidic sites through dissociation mechanisms; the resulting ions can be stabilized by both micropore and interlayer water. We find clay edges possess a complex amphoteric behavior, which depends on the face under consideration and the location of isomorphic substitution. For the neutral (1 1 0) surface, we do not observe any dissociation on the timescale accessible. The edge terminating hydroxyl groups participate in a hydrogen bonded network of water molecules that spans the interlayer between periodic images of the clay framework. With isomorphic substitutions in the tetrahedral layer of the (1 1 0) clay edge, we find the adjacent exposed apical oxygen behaves as a Brönsted base and abstracts a proton from a nearby water molecule, which in turn removes a proton from an AlOH2 group. With isomorphic substitutions in the octahedral layer of the (1 1 0) clay edge the adjacent exposed apical oxygen atom does not abstract a proton from the water molecules, but increases the number of hydrogen bonded water molecules (from one to two). Acid treated clays are likely to have both sites protonated. The (0 1 0) surface does not have the same interfacial hydrogen bonding structure; it is much less stable and we observe dissociation of half the terminal SiOH groups (tbnd Sisbnd Osbnd H → tbnd Sisbnd O- + H+) in our models. The resulting anions are stabilized by solvation from both micropore and interlayer water molecules. This suggests that, when fully hydrated, the (0 1 0) surface can act as a Brönsted acid, even at neutral pH.

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

    Science.gov (United States)

    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.

  1. Clay-chitosan-gold nanoparticle nanohybrid: Preparation and application for assembly and direct electrochemistry of myoglobin

    Energy Technology Data Exchange (ETDEWEB)

    Zhao Xiaojuan; Mai Zhibin [School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275 (China); Kang Xinhuang [College of Science, Guangdong Ocean University, Zhanjiang 524088 (China); Dai Zong [School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275 (China); Zou Xiaoyong [School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275 (China)], E-mail: ceszxy@mail.sysu.edu.cn

    2008-05-30

    A biocompatible nanohybrid material (clay/AuCS) based on clay, chitosan and gold nanoparticles was explored. The material could provide a favorable microenvironment for proteins to realize the direct electron transfer on glassy carbon electrodes (GCE). Myoglobin (Mb), as a model protein to investigate the nanohybrid, was immobilized between the clay/AuCS film and another clay layer. Mb in the system exhibited a pair of well-defined and quasi-reversible redox peaks at -0.160 V (vs. saturated Ag/AgCl electrode) in 0.1 M PBS (pH 7.0), corresponding to its heme Fe{sup III}/Fe{sup II} redox couples. UV-vis spectrum suggested that Mb retained its native conformation in the system. Basal plane spacing of clay obtained by X-ray diffraction (XRD) indicated that there was an intercalation-exfoliation-restacking process among Mb, AuCS and clay during the modified film drying. Excellent biocatalytic activity of Mb in the modified system was exemplified by the reduction of hydrogen peroxide and nitrite. The linear range of H{sub 2}O{sub 2} determination was from 3.9 x 10{sup -5} to 3.0 x 10{sup -3} M with a detection limit of 7.5 {mu}M based on the signal to noise ratio of 3. The kinetic parameters such as {alpha} (charge transfer coefficient), k{sub s} (electron transfer rate constant) and K{sub m} (Michaelis-Menten constant) were evaluated to be 0.55, 2.66 {+-} 0.15 s{sup -1} and 5.10 mM, respectively.

  2. Clay resources in the Netherlands

    NARCIS (Netherlands)

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

    2007-01-01

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

  3. Clay resources in the Netherlands

    NARCIS (Netherlands)

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

    2007-01-01

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

  4. Fluoride retention by kaolin clay

    DEFF Research Database (Denmark)

    Kau, P. M. H.; Smith, D. W.; Binning, Philip John

    1997-01-01

    To evaluate the potential effectiveness of kaolin clay liners in storage of fluoride contaminated waste, an experimental study of the sorption and desorption behaviour of fluoride in kaolin clay was conducted. The degree of fluoride sorption by kaolin was found to depend on solution p...

  5. Viscous property of dried clay

    Institute of Scientific and Technical Information of China (English)

    XU Li-sheng; LI Jian-zhong

    2006-01-01

    One dimensional and triaxial compression tests of air-dried and oven-dried Fujinomori clay and Pisa clay were carried out. Water content is less than 4.5 % and 1.0% for air-dried and oven-dried clay specimens, respectively. In all tests, axial strain rate was changed stepwise many times and drained creep tests were performed several times during monotonic loading at a constant strain rate. Global unloading (and also reloading in some tests) was applied during which creep loading tests were performed several times. Cyclic loading with small stress amplitude and several cycles was also performed to calculate the modulus of elasticity of the clay in tests. Local displacement transducer was used in triaxial compression test to increase measuring accuracy of axial strain. The results show that air-dried and oven-dried clay have noticeable viscous properties; during global unloading, creep deformation changes from positive to negative, i.e. there exist neutral points (zero creep deformation or no creep deformation point) in global unloading part of strain-stress curve; viscous property of Fujinomori clay decreases when water content decreases, i.e. viscous property of air-dried Fujinomori clay is more significant than that of oven-dried Fujinomori clay.

  6. Clay minerals in pollution control

    Energy Technology Data Exchange (ETDEWEB)

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

    2000-07-01

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

  7. Mineral resource of the Month: Clay

    Science.gov (United States)

    Virta, Robert L.

    2010-01-01

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

  8. Novel bentonite clay-based Fe-nanocomposite as a heterogeneous catalyst for photo-Fenton discoloration and mineralization of Orange II.

    Science.gov (United States)

    Feng, Jiyun; Hu, Xijun; Yue, Po Lock

    2004-01-01

    A novel bentonite clay-based Fe-nanocomposite (Fe-B) was successfully developed as a heterogeneous catalyst for photo-Fenton discoloration and mineralization of an azo-dye Orange II. X-ray diffraction (XRD) analysis clearly reveals that the Fe-B nanocomposite catalyst mainly consists of Fe2O3 (hematite) and SiO2 (quartz) crystallites, and the Fe concentration of the Fe-B catalyst determined by X-reflective fluorescence (XRF) is 31.8 wt %. The catalytic activity of the Fe-B was evaluated in the discoloration and mineralization of Orange II in the presence of H2O2 and UVC light (254 nm). It was found that the optimal Fe-B catalyst dosage is around 1.0 g/L, and the efficiency of discoloration and mineralization of Orange II increases as initial Orange II concentration decreases or reaction temperature increases. In addition, at optimal conditions (10 mM H2O2, 1.0 g of Fe-B/L, 1 x 8W UVC, and pH = 3.0), complete discoloration and mineralization of 0.2 mM Orange II can be achieved in less than 60 and 120 min, respectively. The result strongly indicates that the Fe-B nanocomposite catalyst exhibits a high catalytic activity not only in the photo-Fenton discoloration of Orange II but also in the mineralization of Orange II. The reaction kinetics analysis illustrates that the photo-Fenton discoloration of Orange II in the first 15 min obeys the pseudo-first-order kinetics. The reaction activation energy calculated was 9.94 kJ/mol, indicating that the photo-Fenton discoloration of Orange II is not very sensitive to reaction temperature.

  9. Effect of Modified Red Pottery Clay on the Moisture Absorption Behavior and Weatherability of Polyethylene-Based Wood-Plastic Composites

    Directory of Open Access Journals (Sweden)

    Qingde Li

    2017-01-01

    Full Text Available Red pottery clay (RPC was modified using a silane coupling agent, and the modified RPC (mRPC was then used to enhance the performance of high-density polyethylene-based wood-plastic composites. The effect of the mRPC content on the performances of the composites was investigated through Fourier transform infrared spectrometry, differential mechanical analysis (DMA and ultraviolet (UV-accelerated aging tests. After adding the mRPC, a moisture adsorption hysteresis was observed. The DMA results indicated that the mRPC effectively enhanced the rigidity and elasticity of the composites. The mRPC affected the thermal gravimetric, leading to a reduction of the thermal degradation rate and a right-shift of the thermal degradation peak; the initial thermal degradation temperature was increased. After 3000 h of UV-accelerated aging, the flexural strength and impact strength both declined. For aging time between 0 and 1000 h, the increase in amplitude of ΔL* (luminescence and ΔE* (color reached a maximum; the surface fading did not became obvious. ΔL* and ΔE* increased more significantly between 1000 and 2000 h. These characterization results indicate that the chromophores of the mRPC became briefly active. However, when the aging times were higher than 2000 h, the photo-degradation reaction was effectively prevented by adding the mRPC. The best overall enhancement was observed for an mRPC mass percentage of 5%, with a storage modulus of 3264 MPa and an increase in loss modulus by 16.8%, the best anti-aging performance and the lowest degree of color fading.

  10. Cyclic viscoelasticity and viscoplasticity of polypropylene/clay nanocomposites

    DEFF Research Database (Denmark)

    Drozdov, Aleksey; Christiansen, Jesper de Claville; Hog Lejre, Anne-Lise

    2012-01-01

    Observations are reported in tensile relaxation tests under stretching and retraction on poly-propylene/clay nanocomposites with various contents of filler. A two-phase constitutive model is developed in cyclic viscoelasticity and viscoplasticity of hybrid nanocomposites. Adjustable parameters...

  11. Adsorptive Removal of Reactive Black 5 from Wastewater Using Bentonite Clay: Isotherms, Kinetics and Thermodynamics

    Directory of Open Access Journals (Sweden)

    Muhammad Tahir Amin

    2015-11-01

    Full Text Available The studies of the kinetics and isotherms adsorption of the Reactive Black 5 (RB5 onto bentonite clay were explored in a batch study in a laboratory. The maximum RB5 adsorption conditions of bentonite clay were optimized such as shaking speed (100 rpm, temperature (323 K, pH (10, contact time (40 min, initial dye concentration (170 mg·L−1, and particle size (177 µm. The adsorbent surface was characterized using Fourier Transform Infrared Spectroscopy spectroscopy. The mechanisms and characteristic parameters of the adsorption process were analyzed using two parameter isotherm models which revealed the following order (based on the coefficient of determination: Harkin-Jura (0.9989 > Freundlich (0.9986 and Halsey (0.9986 > Langmuir (0.9915 > Temkin (0.9818 > Dubinin–Radushkevich (0.9678. This result suggests the heterogeneous nature of bentonite clay. Moreover, the adsorption process was chemisorption in nature because it follows the pseudo-second order reaction model with R2 value of 0.9998, 0.9933 and 0.9891 at 25, 75 and 100 mg·L−1 RB5 dye in the solution, respectively. Moreover, based on the values of standard enthalpy, Gibbs free energy change, and entropy, bentonite clay showed dual nature of exothermic and endothermic, spontaneous and non-spontaneous as well as increased and decreased randomness at solid–liquid interface at 303–313 K and 313–323 K temperature, respectively.

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

    Science.gov (United States)

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

    2015-06-02

    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.

  13. Viscosity and Plasticity of Latvian Illite Clays

    OpenAIRE

    2012-01-01

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

  14. Adsorption of herbicide paraquat by clay mineral regenerated from spent bleaching earth.

    Science.gov (United States)

    Tsai, Wen-Tien; Lai, Chi-Wei

    2006-06-30

    The adsorption of herbicide paraquat (as model adsorbate) in aqueous solution onto regenerated clay mineral from bleaching earth waste has been studied in a batch reaction system. The adsorption rate has been investigated under the controlled process parameters including initial pH, salinity and temperature. Based on the high affinity between cationic paraquat and clay mineral, a pseudo-second order model has been developed using experimental data to predict the rate constant of adsorption, and equilibrium adsorption capacity. The results showed that the adsorption process could be satisfactorily described with the reaction model and were reasonably explained by assuming a competitive adsorption mechanism in the ion exchange process. Further, the fitted adsorption capacity at equilibrium decreased with increasing temperature. It implied that the strong interaction might play an important role in the paraquat-clay system. Overall, the results from this study demonstrated that the clay resource regenerated from bleaching earth waste could be used as a low-cost mineral adsorbent for the removal of environmental cationic organic pollutants from the aqueous solution.

  15. Benchmarking PET for geoscientific applications: 3D quantitative diffusion coefficient determination in clay rock

    Science.gov (United States)

    Lippmann-Pipke, J.; Gerasch, R.; Schikora, J.; Kulenkampff, J.

    2017-04-01

    The 3D diagonal anisotropic effective diffusion coefficient of Na+, Deff=(Dxx, Dyy, Dzz), was quantified in a clay material in one single experiment/simulation. That is possible due to the combination of the non-invasive observation of Na+ diffusion in Opalinus clay by means of GeoPET method (PET: positron emission tomography) followed by quantitative 3D+t data evaluation by means of the finite element numerical modelling (FEM). The extracted anisotropic effective diffusion coefficient parallel (||) and normal (⊥) to the bedding of the clay rock, Deff=(D||, D⊥, D||) are comparable to those obtained on earlier experimental studies in the same clay material but with different methods. We consider this study as benchmark for the long-standing development of our GeoPET method, that explicitly includes a resolute and physics based attenuation and Compton scatter correction algorithm (Kulenkampff, J., M. Gründig, A. Zakhnini and J. Lippmann-Pipke (2016). "Geoscientific process monitoring with positron emission tomography (GeoPET)." Solid Earth 7: 1217-1231). We suggest GeoPET based fluid flow transport visualization combined with computer based process simulation henceforth as a qualified way for the quantification of three-dimensional, effective transport parameters in geosciences.

  16. Study of the influence of the addition of MMT clay in the preparation of biohydrogel based natural polymers; Estudo da influencia da adicao de argila MMT na preparacao de biohidrogel a base de polimeros naturais

    Energy Technology Data Exchange (ETDEWEB)

    Costa, M.P.M.; Ferreira, I.L.M., E-mail: vanamello@uerj.br [Universidade do Estado do Rio de Janeiro (UERJ), RJ (Brazil). Instituto de Quimica

    2014-07-01

    In this study, biohydrogels were produced from the combination of two polysaccharides (chitosan and sodium alginate). The concentrations of polysaccharide (0.5 to 3% m / m) and clay (0.5 and 2.0%) were varied. CaCl2 was used as a crosslinking agent. The samples were characterized by thermogravimetry (thermal stability), FTIR (chemical composition), scanning electron microscopy (SEM), and X-ray diffraction. The present work aims to study the influence of different clay content in biohydrogel produced. In the presence of clay, a differentiated morphology was observed by SEM. The degree of swelling was evaluated as a function of the composition of each mixture. The presence of clay caused a significant swelling of the hydrogel on the water absorption when the clay content was increased. The FTIR spectra showed the presence of characteristic bands of each polysaccharide, and the clay. The XRD showed that the amorphous presented biohydrogel behavior. (author)

  17. Potentiality of laboratory visible and near infrared spectroscopy for determining clay content in forest soil: a case study from high forest beech (fagus sylvatica in Calabria (southern Italy

    Directory of Open Access Journals (Sweden)

    Massimo Conforti

    2014-01-01

    Full Text Available Clay content is the most important textural fraction because affects soil fertility and productivity.Reflectance spectroscopy in the visible and near infrared (Vis-NIR, 350-2500 nm spectral region could be an alternative to laboratory standard methods.This paper was aimed to develop a calibration model with laboratory-based soil Vis-NIR spectra for clay content determination and mapping clay content using a geostatistical approach.Soil samples were collected at 235 locations in a forest area of southern Italy and analyzed in laboratory for clay content and Vis-NIR spectroscopic measurements.Partial least squared regression (PLSR was applied to establish a relationships between reflectance and clay content. Calibration model was developed using only 175 samples, while the remaining 60 samples were used for testing the model. The results of PLSR were satisfactory and ordinary kriging was used for spatial interpolation of clay content determined both using conventional method and the PLSR model.

  18. Microbial diversity in opalinus clay and interaction of dominant microbial strains with actinides

    Energy Technology Data Exchange (ETDEWEB)

    Moll, Henry; Luetke, Laura; Bachvarova, Velina; Steudtner, Robin; Geissler, Andrea; Krawczyk-Baersch, Evelyn; Selenska-Pobell, Sonja; Bernhardt, Gert

    2013-07-01

    For the first time microbial tDNA could be isolated from 50 g unperturbed Mont Terri Opalinus Clay. Based on the analysis of the tDNA the bacterial diversity of the unperturbed clay is dominated by representatives of Firmicutes, Betaproteobacteria, and Bacteriodetes. Firmicutes also dominate after treatment of the clay with R2A medium. Bacteria isolated from Mont Terri Opalinus Clay on R2A medium were related to Sporomusa spp., Paenibacillus spp., and Clostridium spp. All further investigations are concentrated on the unique isolates Sporomusa sp. MT-2 and Paenibacillus sp. MT-2. Cells of the type Sporomusa sp. MT-2 and Paenibacillus sp. MT-2 were comprehensively analyzed in terms of growing, morphology, functional groups of the cell envelope, and cell membrane structure. Strong actinide(An)/lanthanide(Ln)-interactions with the Opalinus Clay isolates and the Aespoe-strain Pseudomonas fluorescens (CCUG 32456) could be determined within a broad pH range (2-8). The metals bind as a function of pH on protonated phosphoryl, carboxyl and deprotonated phosphoryl sites of the respective cell membrane. The thermodynamic surface complexation constants of bacterial An/Ln-species were determined and can be used in modeling programs. Depending on the used An different interaction mechanisms were found (U(VI): biosorption, partly biomineralisation; Cm(III): biosorption, indications for embedded Cm(III); Pu: biosorption, bioreduction and indications for embedded Pu). Different strategies of coping with U(VI) were observed comparing P. fluorescens planktonic cells and biofilms under the chosen experimental conditions. An enhanced capability of the biofilm to form meta-autunite in comparison to the planktonic cells was proven. Conclusively, the P. fluorescens biofilm is more efficient in U(VI) detoxification. In conclusion, Mont Terri Opalinus Clay contains bacterial communities, that may influence the speciation and hence the migration behavior of selected An/Ln under

  19. RESEARCH OF SWELLING OF SUZAKH CLAYS

    Directory of Open Access Journals (Sweden)

    Kubetskiy Valeriy Leonidovich

    2012-07-01

    Full Text Available In the course of construction of Sangtudinsky hydropower plant-1 on the River Vakhsh, it was deemed necessary to identify clay swelling properties in the event of alterations of the humidity mode of fructured half-rock soils, or the Suzakh clay, that accommodated tunnel-shaped water outlets within a section that was 75 meters long. The depth of tunnels was about 100 m. Any interaction with swelling soils could lead to destruction of the tunnel lining. Suzakh clays demonstrated the following physical and mechanical properties: density of particles of soil ρ= 2,69 g/cm; soil density ρ = 2.40-2.47 g/cm; porosity of 8.2-10.8 %; ultimate resistance to uniaxial compression = 13.1-31.0 MPa. Water saturated clay samples disintegrated into cloddy fragments; the rate of a longitudinal ultrasonic wave in the area of unaltered soils was equal to = 2500 m/c; repulse coefficient k was equal to 15 MPa/m; solidity coefficient (according to Protodyakonov was equal to 1,5; modulus of deformation in the massif was equal to 0.23 х10 MPa. The author proposed a methodology and designed a pilot set of equipment units designated for the identification of the swelling properties of fractured half-rock soils. Results of the pilot unit operation are presented in the article. Swelling properties are based on the monolith testing results. The programme contemplated a set of experiments held in various limit states on the surface of monoliths. Dependence between the swelling pressure and the swelling deformation in the course of water saturation was identified. The experiment demonstrates that alterations of the humidity mode of free surface Suzakh clays cause the relative deformation of swelling up to 1.1 %, and if the lining is rigid, the swelling pressure can exceed 4 MPa.

  20. Research on mechanical models of a new clay chip drill used in trenchless drilling%非开挖钻孔新型碎泥屑钻头力学模型研究

    Institute of Scientific and Technical Information of China (English)

    李小平; 刘海兰; 芮延年

    2013-01-01

    Through study of pneumatic conveying and soil damage theory and experiencing advanced drill structure of our country and abroad,a new asymmetrical clay chip drill is designed which has break chip groove and variable -pitch and is used dry clay chip pneumatic conveying in the process of trenchless drilling of urban road .The mechanical models are established after the me-chanical analysis when the drill working .It is the basis of optimization of the drill parameters and structure design and calculation of trenchless drilling robots with dry clay chip pneumatic conveying systems .%通过对气力输送技术和土的破坏理论的研究,借鉴目前国内外先进的钻尖结构,设计了一种适用于市政道路非开挖干法输送泥屑的非对称断屑槽变螺距螺旋面的新型钻头。通过对该钻头工作时的受力分析,建立了钻头的力学模型,为钻头参数的进一步优化及干法气力输送非开挖钻孔机器人的结构设计与计算奠定了理论基础。

  1. Resin injection in clays with high plasticity

    Science.gov (United States)

    Nowamooz, Hossein

    2016-11-01

    Regarding the injection process of polyurethane resins in clays with high plasticity, this paper presents the experimental results of the pressuremeter and cone penetration tests before and after injection. A very important increase in pressure limit or in soil resistance can be observed for all the studied depths close to the injection points. An analytical analysis for cylindrical pore cavity expansion in cohesive frictional soils obeying the Mohr-Coulomb criterion was then used to reproduce the pressuremeter tests before and after injection. The model parameters were calibrated by maintaining constant the elasticity parameters as well as the friction angel before and after injection. A significant increase in cohesion was observed because of soil densification after resin expansion. The estimated undrained cohesions, derived from the parameters of the Mohr-Coulomb criterion, were also compared with the cone penetration tests. Globally, the model predictions show the efficiency of resin injection in clay soils with high plasticity.

  2. Shear Strength Behavior of Two Landfill Clay Liners

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Direct shear tests were conducted to obtain both the shear strength of compacted clay liners (CCLs) specimens and the interface shear strength between compacted clay liner and base soil. These experiments were conducted under the conditions of five different water contents. The experimental results show that shear strength of both CCLs and CCLs/base interface decreases with the increase in the water content of CCLs and base soil. In addition, the considerate concentration of NaCl in leachate has no deteriorating effect on the shear strength of liners. Triaxial shear tests were also conducted on clay liner specimens to obtain total and effective shear strength under a fast compression. The shear strength c'=100 kPa for sand-bentonite, respectively. These results indicate that the compacted clay-bentonite shows normal consolidation, but that the compacted sand-bentonite exhibits over-consolidation.

  3. Clay membrane made of natural high plasticity clay:

    DEFF Research Database (Denmark)

    Foged, Niels; Baumann, Jens

    1999-01-01

    -type. The clay material has been evaluated using the standardized methods related to mineralogy, classification, compaction and permeability, and initial studies of diffusion properties have been carried out. Furthermore, at a test site the construction methods for establishing a 0.15-0.3 m thick clay membrane...... have been tested successfully. At a natural water content of w=40-45% it is possible to establish a homogeneous membrane with hydraulic conductivity k...

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

    Science.gov (United States)

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

    2017-02-24

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

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

    Science.gov (United States)

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

    2017-01-01

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

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

    Science.gov (United States)

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

    2017-02-01

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

  7. Microbe-Clay Mineral Reactions and Characterization Techniques

    Science.gov (United States)

    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

  8. Catalyzed Synthesis of Zinc Clays by Prebiotic Central Metabolites.

    Science.gov (United States)

    Zhou, Ruixin; Basu, Kaustuv; Hartman, Hyman; Matocha, Christopher J; Sears, S Kelly; Vali, Hojatollah; Guzman, Marcelo I

    2017-04-03

    How primordial metabolic networks such as the reverse tricarboxylic acid (rTCA) cycle and clay mineral catalysts coevolved remains a mystery in the puzzle to understand the origin of life. While prebiotic reactions from the rTCA cycle were accomplished via photochemistry on semiconductor minerals, the synthesis of clays was demonstrated at low temperature and ambient pressure catalyzed by oxalate. Herein, the crystallization of clay minerals is catalyzed by succinate, an example of a photoproduced intermediate from central metabolism. The experiments connect the synthesis of sauconite, a model for clay minerals, to prebiotic photochemistry. We report the temperature, pH, and concentration dependence on succinate for the synthesis of sauconite identifying new mechanisms of clay formation in surface environments of rocky planets. The work demonstrates that seeding induces nucleation at low temperatures accelerating the crystallization process. Cryogenic and conventional transmission electron microscopies, X-ray diffraction, diffuse reflectance Fourier transformed infrared spectroscopy, and measurements of total surface area are used to build a three-dimensional representation of the clay. These results suggest the coevolution of clay minerals and early metabolites in our planet could have been facilitated by sunlight photochemistry, which played a significant role in the complex interplay between rocks and life over geological time.

  9. Preparation and properties of biodegradable starch–clay nanocomposites

    KAUST Repository

    Chung, Yi-Lin

    2010-01-01

    Well-dispersed starch-clay nanocomposites were prepared by adding a dilute clay dispersion to a solution of starch followed by coprecipitation in ethanol. The clay didn\\'t significantly influence the type of crystalline structure of starch molecules although the amount of crystallinity appears to be somewhat lower in the nanocomposites. The nanocomposites show improved modulus and strength without a decrease in elongation at break. The increase in modulus and strength is 65% and 30%, respectively for the nanocomposite containing 5 wt.% clay compared to the unfilled starch materials. Further increases in clay result in deterioration in properties most likely due to poorer clay dispersion and lower polymer crystallinity. As the amount of water increases, the modulus of both pure starch and starch nanocomposites decreases, although the change is less pronounced in the nanocomposites suggesting that the addition of clay to form nanocomposites can improve the stability of starch-based products during transportation and storage. © 2009 Elsevier Ltd. All rights reserved.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  11. Colloidal gels: Clay goes patchy

    Science.gov (United States)

    Kegel, Willem K.; Lekkerkerker, Henk N. W.

    2011-01-01

    Empty liquids and equilibrium gels have so far been only theoretical possibilities, predicted for colloids with patchy interactions. But evidence of both has now been found in Laponite, a widely studied clay.

  12. Solar active fire clay based hetero-Fenton catalyst over a wide pH range for degradation of Acid Violet 7

    Institute of Scientific and Technical Information of China (English)

    Inbasekaran Muthuvel; Balu Krishnakumar; Meenakshisundaram Swaminathan

    2012-01-01

    Fe(Ⅲ)immobilized fire clay(Fe-FC)was prepared using ferric nitrate by solid state dispersion method and this hetero-Fenton catalyst was applied for the degradation of Acid Violet 7(AV 7)under natural sunlight.The 26% ferric nitrate loaded fire clay was found to be most efficient.The experimental conditions such as solution pH,H2O2 concentration for efficient degradation of AV 7 have been determined.Unlike Fenton catalyst,Fe-FC is photoactive over a wide pH range of 3-7.This catalyst was found to be stable and reusable.The G-C-MS analysis of experimental solutions during irradiation revealed the formation of 2,8-diaminonaphthalene-1,3,6-triol,8-aminonaphthalene-1,2,3,6-tetrol,2-aminonaphthalene-1,3,6,8-tetrol and 2-aminobenzene-1,3-diol/5-aminonbenzene-1,3-diol/2-aminobenzene-1,4-diol as intermediates.The 26% ferric nitrate loaded fire clay was characterized by XRD,ICP-AES,BET surface area,FT-IR,SEM-EDS and UV-DRS studies.

  13. Effects of temperature and thermally-induced microstructure change on hydraulic conductivity of Boom Clay

    Directory of Open Access Journals (Sweden)

    W.Z. Chen

    2017-06-01

    behaviour of Boom Clay. Based on the experimental results, a hydraulic conductivity evolution model is proposed and then implemented in ABAQUS. Three-dimensional (3D numerical simulation of the admissible thermal loading for argillaceous storage (ATLAS III in situ heating test has been conducted subsequently, and the numerical results are in good agreement with field measurements.

  14. Stress-strain relations for swelling anhydritic clay rocks – A review

    Science.gov (United States)

    Breuer, Simon; Blum, Philipp; Butscher, Christoph

    2015-04-01

    The swelling of clay-sulfate rocks is a major threat in tunnel engineering, causing serious damage to tunnels and producing high additional costs during tunnel construction and operation. The swelling leads to geomechanical processes that may result in heave of the tunnel invert, destruction of the lining or uplift of the entire tunnel section. Heave-pressure-time relations are needed when predictions should be made about the mechanical behavior of swelling rock. For pure clay rocks, there is a linear relation between the swelling heave (strain) and the logarithm of pressure (Grob 1972). A generally accepted relation for clay-sulfate rocks, however, is still lacking to date. Therefore, finding appropriate and sustainable counter measures for an actual tunneling project affected by swelling remains extremely difficult. Grob (1972) proposed the linear relation between heave and the logarithm of pressure ("semi-logarithmic swelling law") not only for clay rocks, but also for clay-sulfate rocks. Pimentel (2007), however, presented laboratory experiments indicating that the semi-logarithmic swelling law may be inadequate for describing the swelling of clay-sulfate rocks. The laboratory tests revealed three different stages in the swelling process, including minimal deformation and prevented gypsum crystallization at high pressures (> 6 MPa); large deformation and gypsum crystallization at medium pressures; and only small deformation, possibly along with gypsum dissolution, at low pressures (water inflow into the rock, which cannot be reflected by general strain-stress relations. The present study critically reviews stress-strain relations for swelling anhydritic clay rocks proposed by various authors. Subsequently, published laboratory data from oedometric swelling tests are presented that may confirm the proposed stress-strain relationships. Finally, these data are re-examined by comparing each of the proposed relations with the same data set. Based on these results, a

  15. Porosity Investigation of Kosova's Clay

    OpenAIRE

    Makfire Sadiku; Naim Hasani; Altin Mele

    2011-01-01

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

  16. Clays in radioactive waste disposal

    OpenAIRE

    Delage, Pierre; Cui, Yu-Jun; Tang, Anh-Minh

    2010-01-01

    Clays and argillites are considered in some countries as possible host rocks for nuclear waste disposal at great depth. The use of compacted swelling clays as engineered barriers is also considered within the framework of the multi-barrier concept. In relation to these concepts, various research programs have been conducted to assess the thermo-hydro-mechanical properties of radioactive waste disposal at great depth. After introducing the concepts of waste isolation developed in Belgium, Fran...

  17. Model Based Definition

    Science.gov (United States)

    Rowe, Sidney E.

    2010-01-01

    In September 2007, the Engineering Directorate at the Marshall Space Flight Center (MSFC) created the Design System Focus Team (DSFT). MSFC was responsible for the in-house design and development of the Ares 1 Upper Stage and the Engineering Directorate was preparing to deploy a new electronic Configuration Management and Data Management System with the Design Data Management System (DDMS) based upon a Commercial Off The Shelf (COTS) Product Data Management (PDM) System. The DSFT was to establish standardized CAD practices and a new data life cycle for design data. Of special interest here, the design teams were to implement Model Based Definition (MBD) in support of the Upper Stage manufacturing contract. It is noted that this MBD does use partially dimensioned drawings for auxiliary information to the model. The design data lifecycle implemented several new release states to be used prior to formal release that allowed the models to move through a flow of progressive maturity. The DSFT identified some 17 Lessons Learned as outcomes of the standards development, pathfinder deployments and initial application to the Upper Stage design completion. Some of the high value examples are reviewed.

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

    Institute of Scientific and Technical Information of China (English)

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

    2001-01-01

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

  19. What makes a natural clay antibacterial?

    Science.gov (United States)

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

    2011-01-01

    Natural clays have been used in ancient and modern medicine, but the mechanism(s) that make certain clays lethal against bacterial pathogens has not been identified. We have compared the depositional environments, mineralogies, and chemistries of clays that exhibit antibacterial effects on a broad spectrum of human pathogens including antibiotic resistant strains. Natural antibacterial clays contain nanoscale (2+ solubility.

  20. Fine-resolution multiscale mapping of clay minerals in Australian soils measured with near infrared spectra

    Science.gov (United States)

    Viscarra Rossel, R. A.

    2011-12-01

    Clay minerals are the most reactive inorganic components of soils. They help to determine soil properties and largely govern their behaviors and functions. Clay minerals also play important roles in biogeochemical cycling and interact with the environment to affect geomorphic processes such as weathering, erosion and deposition. This paper provides new spatially explicit clay mineralogy information for Australia that will help to improve our understanding of soils and their role in the functioning of landscapes and ecosystems. I measured the abundances of kaolinite, illite and smectite in Australian soils using near infrared (NIR) spectroscopy. Using a model-tree algorithm, I built rule-based models for each mineral at two depths (0-20 cm, 60-80 cm) as a function of predictors that represent the soil-forming factors (climate, parent material, relief, vegetation and time), their processes and the scales at which they vary. The results show that climate, parent material and soil type exert the largest influence on the abundance and spatial distribution of the clay minerals; relief and vegetation have more local effects. I digitally mapped each mineral on a 3 arc-second grid. The maps show the relative abundances and distributions of kaolinite, illite and smectite in Australian soils. Kaolinite occurs in a range of climates but dominates in deeply weathered soils, in soils of higher landscapes and in regions with more rain. Illite is present in varied landscapes and may be representative of colder, more arid climates, but may also be present in warmer and wetter soil environments. Smectite is often an authigenic mineral, formed from the weathering of basalt, but it also occurs on sediments and calcareous substrates. It occurs predominantly in drier climates and in landscapes with low relief. These new clay mineral maps fill a significant gap in the availability of soil mineralogical information. They provide data to for example, assist with research into soil

  1. Wave liquefaction in soils with clay content

    DEFF Research Database (Denmark)

    Kirca, Özgür; Sumer, B. Mutlu; Fredsøe, Jørgen

    2012-01-01

    The paper presents the results of an experimental study of the influence of clay content (in silt-clay and sand-clay mixtures) on liquefaction beneath progressive waves. The experiments showed that the influence of clay content is very significant. Susceptibility of silt to liquefaction...... is increased with increasing clay content, up to 30%, beyond which the mixture of silt and clay is not liquefied. Sand may become prone to liquefaction with the introduction of clay, contrary to the general perception that this type of sediment is normally liquefaction resistant under waves....

  2. Mössbauer Spectra of Clays and Ceramics

    Science.gov (United States)

    Wagner, F. E.; Wagner, U.

    2004-06-01

    The physical, chemical and mineralogical aspects of the use of Mössbauer spectroscopy in studies of clay-based ceramics are described. Mössbauer spectra of pottery clays fired under oxidising, reducing and changing conditions are explained, and the possibilities of using Mössbauer spectra to derive information on the firing temperatures and the kiln atmosphere during firing in antiquity are discussed and illustrated by examples.

  3. 81 FR 31234 - NESHAP for Brick and Structural Clay Products Manufacturing; and NESHAP for Clay Ceramics...

    Science.gov (United States)

    2016-05-18

    ... AGENCY NESHAP for Brick and Structural Clay Products Manufacturing; and NESHAP for Clay Ceramics... Brick and Structural Clay Products (BSCP) Manufacturing and the final NESHAP for Clay Ceramics... No. EPA-HQ-OAR-2013-0290 for Clay Ceramics Manufacturing. All documents in the dockets are listed...

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

    Science.gov (United States)

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

    2015-12-01

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

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

    Directory of Open Access Journals (Sweden)

    Simona eLongo

    2013-11-01

    Full Text Available Supercritical carbon dioxide (scCO2 treatments of a montmorillonite (MMT intercalated with ammonium cations bearing two long hydrocarbon tails (organo-modified MMT, OMMT led to OMMT exfoliation, with loss of the long-range order in the packing of the hydrocarbon tails and maintenance of the long-range order in the clay layers. The intercalated and the derived exfoliated OMMT have been deeply characterized, mainly by X-ray diffraction analyses. Monolithic composite aerogels, with large amounts of both intercalated and exfoliated OMMT and including the nanoporous-crystalline δ form of syndiotactic polystyrene (s-PS, have been prepared, by scCO2 extractions of s-PS-based gels. Also for high OMMT content, the gel and aerogel preparation procedures occur without re-aggregation of the exfoliated clay, which is instead observed for other kinds of polymer processing. Aerogels with the exfoliated OMMT have more even dispersion of the clay layers, higher elastic modulus and larger surface area than aerogels with the intercalated OMMT. Extremely light materials with relevant transport properties could be prepared. Moreover, s-PS-based aerogels with exfoliated OMMT could be helpful for the handling of exfoliated clay minerals.

  6. Adhesion of E. coli to silver- or copper-coated porous clay ceramic surfaces

    Science.gov (United States)

    Yakub, I.; Soboyejo, W. O.

    2012-06-01

    Porous ceramic water filters (CWFs), produced by sintering a mixture of clay and a combustible material (such as woodchips), are often used in point-of-use water filtration systems that occlude microbes by size exclusion. They are also coated with colloidal silver, which serves as a microbial disinfectant. However, the adhesion of microbes to porous clay surfaces and colloidal silver coated clay surfaces has not been studied. This paper presents the results of atomic force microscopy (AFM) measurements of the adhesion force between Escherichia coli bacteria, colloidal silver, and porous clay-based ceramic surfaces. The adhesion of silver and copper nanoparticles is also studied in control experiments on these alternative disinfectant materials. The adhesive force between the wide range of possible bi-materials was measured using pull-off measurements during force microscopy. These were combined with measurements of AFM tip radii/substrate roughness that were incorporated into adhesion models to obtain the adhesion energies for the pair wise interaction. Of the three antimicrobial metals studied, the colloidal silver had the highest affinity for porous ceramic surface (125 ± 32 nN and ˜0.29 J/m2) while the silver nanoparticles had the highest affinity for E. coli bacteria (133 ± 21 nN and ˜0.39 J/m2). The implications of the results are then discussed for the design of ceramic water filter that can purify water by adsorption and size exclusion.

  7. Coupled Heat and Moisture Transport Simulation on the Re-saturation of Engineered Clay Barrier

    Science.gov (United States)

    Huang, W. H.; Chuang, Y. F.

    2014-12-01

    Engineered clay barrier plays a major role for the isolation of radioactive wastes in a underground repository. This paper investigates the resaturation processes of clay barrier, with emphasis on the coupling effects of heat and moisture during the intrusion of groundwater to the repository. A reference bentonite and a locally available clay were adopted in the laboratory program. Soil suction of clay specimens was measured by psychrometers embedded in clay specimens and by vapor equilibrium technique conducted at varying temperatures so as to determine the soil water characteristic curves of the two clays at different temperatures. And water uptake tests were conducted on clay specimens compacted at various densities to simulate the intrusion of groundwater into the clay barrier. Using the soil water characteristic curve, an integration scheme was introduced to estimate the hydraulic conductivity of unsaturated clay. It was found that soil suction decreases as temperature increases, resulting in a reduction in water retention capability. The finite element method was then employed to carry out the numerical simulation of the saturation process in the near field of a repository. Results of the numerical simulation were validated using the degree of saturation profile obtained from the water uptake tests on the clays. The numerical scheme was then extended to establish a model simulating the resaturation process after the closure of a repository. Finally, the model was then used to evaluate the effect of clay barrier thickness on the time required for groundwater to penetrate the clay barrier and approach saturation. Due to the variation in clay suction and thermal conductivity with temperature of clay barrier material, the calculated temperature field shows a reduction as a result of incorporating the hydro-properties in the calculations.

  8. Compaction of microfossil and clay-rich chalk sediments

    DEFF Research Database (Denmark)

    Fabricius, Ida Lykke

    2001-01-01

    The aim of this study was to evaluate the role of microfossils and clay in the compaction of chalk facies sediments. To meet this aim, chalk sediments with varying micro texture were studied. The sediments have been tested uniaxially confined in a stainless-steel compaction cell. The sediments are......: 1) Pure carbonate chalk with mudstone texture from Stevns Klint (Denmark), 2) Relatively pure chalk sediments with varying content of microfossils from the Ontong Java Plateau (Western Pacific), 3) Clay-rich chalk and mixed sediments from the Caribbean. The tested samples were characterised...... of microfossils and fine-grained silica and clay. Samples with relatively pure chalk mud supported texture compact along a common stress - matrix porosity trend. Microfossils thus have a passive role, apparently because they are supported by the chalk mud. Samples with fine-grained silica and clay can be modelled...

  9. Water diffusion through compacted clays analyzed by neutron scattering and tracer experiments

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez Sanchez, F

    2007-11-15

    Clay minerals are aluminium phyllosilicates, mostly products of the chemical alteration and mechanical breakdown of igneous and metamorphic rocks. Their physical and chemical properties can be directly related to their layered, fine-grained (large surface area) structure. These properties such as large water retention, low hydraulic conductivity, heat resistance and ionic exchange capacities, make clays ideal for many different applications, e.g. as sealing material for the underground disposal of radioactive waste. The long-term disposal of radioactive waste in an underground geological repository is based on a multibarrier concept. In the barrier of highly compacted clay, water is intercalated and confined between the clay layers. The narrow pores are responsible that under natural hydraulic gradients, molecular diffusion through water is the dominant transport mechanism for released radionuclides. The properties of water at the water-clay interface differ from that of bulk water. Therefore, a good and deep understanding of the water structure and dynamics in compacted clay systems is fundamental. This knowledge is the base for the progressing research about transport of pollutants through the compacted clays and argillaceous rock of radioactive waste barriers. This study focusses on four different types of pure clays, two of them charged, namely montmorillonite and illite (both in a Na and Ca form), and two uncharged, namely kaolinite and pyrophyllite. Their structural differences result in a significantly different behaviour in contact with water. In case of montmorillonite, water is located in between particles and in the interlayer space. In illite, water is found only in between particles, because the interlayer surfaces are tightly linked by potassium cations. The layers of kaolinite and pyrophyllite are uncharged and, consequently, water is located only in between particles. The clay powders were compacted to reach a high bulk dry density of about 1.9 g

  10. RADIATION SYNTHESIS AND CHARACTERIZATION OF POLY (AA-CO-NVP)/CLAY HYDROGELS

    Institute of Scientific and Technical Information of China (English)

    Hong-yan Song; Wen-tao Liu; Su-qin He; Ming-cheng Yang; Ya Gao; Cheng-shen Zhu; Liu-suo Wu

    2008-01-01

    The pH-sensitive P(AA-co-NVP)Iclay hydrogels were prepared with the monomers of acrylic acid (AA) andN-vinyl-2-pyrrolidone (NVP) based on γ-ray irradiation technique. The influence of pH values of buffer solutions andcontents of clay and NVP on the equilibrium swelling ratio (SR) and compressive properties of the hydrogels wasinvestigated in detail. The results of swelling property tests showed that, with the increase of clay content, the SR ofhydrogels increases in the same buffer solution, and the SR of hydrogels with different contents of HTMAB-clay is higherthan that of P(A.A-co-NVP) hydrogels without clay. When the content of clay is 15%, the SR of P(AA-co-NVP)/clayhydrogel is 201 at pH=9.8, which is 1.23 times of that of the P(AA-co-NVP) hydrogel (164). In addition, the SR ofP(AA-co-NVP)/clay hydrogel is higher than that of PAA/clay hydrogel in the same solution. The compressive properties ofthe hydrogel were also examined. The results showed that the compressive properties of the P(AA-co-NVP)/clay hydrogelswere improved distinctly as compared to those of the conventional hydrogels without clay. When the content of clay is 15%,the compression strength of the P(AA-co-NVP)/clay hydrogel is 23 times of that of the P(AA-co-NVP) hydrogel.

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

    Science.gov (United States)

    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.

  12. Research on Softening Model of Soft Clay under Wave Load%波浪荷载作用下软黏土软化模型研究

    Institute of Scientific and Technical Information of China (English)

    付培帅; 唐小微; 韩小凯; 刘功勋

    2015-01-01

    波浪荷载能引起海床土体的主应力轴连续旋转。不同于地震、交通等循环荷载,在周期性波浪荷载作用的土体应力路径方式下,软黏土的软化效用更为明显。本文分别对天然和扰动的海床土体在波浪荷载作用下的应力响应进行模拟,并分析应力路径的特点;为描述软化后的应力-应变关系,将软化效用和累积塑性应变的参数引入到能够反应土体动力非线性的 Hardin-Drnevich 模型中,建立修正模型,使之能够反应软黏土体软化与塑性应变累计特性;通过与模拟波浪荷载下土体应力特征的循环耦合试验结果进行对比分析,验证该修正模型的可靠性。%Wave load causes continuous rotation of the principal stress axes of seabed soil.Unlike seismic load and traffic load,under the action of cyclical wave load,stiffness softening of soft clay is much more obvious.Numerical simulation is applied to obtain the stress response of undis-turbed and disturbed seabed soil,and to analyze the characteristics of the stress path.Under wave loads,the main feature of the seabed soil is the continuous rotation of its maximum principal stress axis;the maximum principal stress’cycle is similar to the wave load cycles.Under the in-fluence of the structure in the seabed disturbance,the soil’s stress path changed under the wave load,and the factors that affect the stress path can be generalized using the initial principal stress orientation,the initial stress ratio,the angle of the major principal stress direction,and other fac-tors.To describe the relation of a soil’s stress and strain after stiffness softening,two parameters were introduced to the Haridin-Drnevich model to reflect the stiffness softening and cumulative plastic strain phenomenon,and these two parameters are a function of the soil’s initial status, which influences its stress path under wave load.The cyclic coupling shear tests can probably sim-ulate the

  13. PREPARATION OF POZZOLAN WITH A RAW CLAY MATERIAL FROM BURKINA FASO / PREPARATION D’UNE POUZZOLANE A BASE D’UNE MATIERE PREMIERE ARGILEUSE DU BURKINA FASO

    OpenAIRE

    François Ganon; Adama Yameogo; Brahima Sorgho; Lamine Zerbo; Mohamed Seynou; Younoussa Millogo; Raguilnaba Ouedraogo

    2016-01-01

    A raw clay material from Burkina Faso has been characterized for pozzolan elaboration. The analysis showed that SiO2 (45.91 wt. %), Al2O3 (28.29 wt. %) and Fe2O3 (9.75 wt. %) are the main oxides and kaolinite (71 wt. %) is the principle mineral. The sample has been activated at 680 °C during 2 or 5 hours. The pozzolanic activity has been accessed by coupling several methods. The chemical methods showed the good lime fixing ability by the activated sample. At the first 24 hours, more t...

  14. Charm of Purple Clay A private museum in Wuxi is devoted to purple-clay art

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Purple-clay art pieces will be on display in a museum opening soon in Wuxi, Jiangsu Province. The museum, named Shuaiyuan Purple Clay Museum, is part of the Shuaiyuan Purple Clay Art Exhibition Center

  15. Laboratory evaluation of cement treated aggregate containing crushed clay brick

    Directory of Open Access Journals (Sweden)

    Liqun Hu

    2014-10-01

    Full Text Available The waste clay bricks from debris of buildings were evaluated through lab tests as environmental friendly materials for pavement sub-base in the research. Five sets of coarse aggregates which contained 0, 25%, 50%, 75% and 100% crushed bricks, respectively, were blended with sand and treated by 5% cement. The test results indicated that cement treated aggregate which contains crushed clay brick aggregate had a lower maximum dry density (MDD and a higher optimum moisture content (OMC. Moreover, the unconfined compressive strength (UCS, resilience modulus, splitting strength, and frost resistance performance of the specimens decreased with increase of the amount of crushed clay brick aggregate. On the other hand, it can be observed that the use of crushed clay brick in the mixture decreased the dry shrinkage strain of the specimens. Compared with the asphalt pavement design specifications of China, the results imply that the substitution rate of natural aggregate with crushed clay brick aggregate in the cement treated aggregate sub-base material should be less than 50% (5% cement content in the mixture. Furthermore, it needs to be noted that the cement treated aggregate which contains crushed clay bricks should be cautiously used in the cold region due to its insufficient frost resistance performance.

  16. Near Field sorption Data Bases for Compacted MX-80 Bentonite for Performance Assessment of a High-Level Radioactive Waste Repository in Opalinus Clay Host Rock

    Energy Technology Data Exchange (ETDEWEB)

    Bradbury, M.; Baeyens, B

    2003-08-01

    Bentonites of various types and compacted forms are being investigated in many countries as backfill materials in high-level radioactive waste disposal concepts. Nagra is currently considering an Opalinus clay (OPA) formation in the Zuercher Weinland as a potential location for a high-level radioactive waste repository. A compacted MX-80 bentonite is foreseen as a potential backfill material. Performance assessment studies will be performed for this site and one of the requirements for such an assessment are sorption data bases (SDB) for the bentonite near-field. The purpose of this report is to describe the procedures used to develop the SDB. One of the pre-requisites for developing a SDB is a water chemistry for the compacted bentonite porewater. For a number of reasons mentioned in the report, and discussed in more detail elsewhere, this is not a straightforward task. There are considerable uncertainties associated with the major ion concentrations and in particular with the system pH and Eh. The MX-80 SDB was developed for a reference bentonite porewater (pH = 7.25) which was calculated using the reference OPA porewater. In addition, two further SDBs are presented for porewaters calculated at pH values of 6.9 and 7.9 corresponding to lower and upper bound values calculated for the range of groundwater compositions anticipated for the OPA host rock. 'In house' sorption isotherm data were measured for Cs(I), Ni(II), Eu(III), Th(IV), Se(IV) and 1(-1) on the 'as received' MX-80 material equilibrated with a simulated porewater composition. Complementary 'in house' sorption edge and isotherm measurements on conditioned Na/Ca montmorillonites were also available for many of these radionuclides. These data formed the core of the SDB. Nevertheless, some of the required sorption data still had to be obtained from the open literature. An important part of this report is concerned with describing selection procedures and the modifications

  17. Micromechanical analysis of the behavior of stiff clay

    Institute of Scientific and Technical Information of China (English)

    Zhen-Yu Yin; Ching S. Chang; Pierre-Yves Hicher; Jian-Hua Wang

    2011-01-01

    Cementations formed in geological timescale are observed in various stiff clays.A micromechanical stress strain model is developed for modeling the effect of cementation on the deformation behavior of stiff clay.The proposed approach considers explicitly cementations at intercluster contacts,which is different from conventional model.The concept of inter-cluster bonding is introduced to account for an additional cohesion in shear sliding and a higher yield stress in normal compression.A damage law for inter-cluster bonding is proposed at cluster contacts for the debonding process during mechanical loading.The model is used to simulate numerous stress-path tests on Vallericca stiff clay.The applicability of the present model is evaluated through comparisons between the predicted and the measured results.In order to explain the stress-induced anisotropy arising from extemally applied load,the evolution of local stresses and local strains at inter-cluster planes are discussed.

  18. Impact of Clay DNAPL Interactions on Transport and Storage of Chlorinated Solvents in Low Permeability Zones

    Science.gov (United States)

    2015-02-01

    with PCE-based DNAPL waste for 18 days, B) Na- bentonite taken from the clay layer surface from a beaker containing TCE-based DNAPL waste ponded on...top of the water-saturated clay for 105 days; and C) Na- bentonite taken from beneath the clay layer surface from a beaker containing TCE-based...DNAPL waste ponded on top of the water- ix saturated clay layer for 105 days. 46 Figure 3.5. Photographs showing the cracking of Na- bentonite in

  19. 80 FR 75817 - NESHAP for Brick and Structural Clay Products Manufacturing; and NESHAP for Clay Ceramics...

    Science.gov (United States)

    2015-12-04

    ... NESHAP for Clay Ceramics Manufacturing: Correction AGENCY: Environmental Protection Agency (EPA). ACTION...; and NESHAP for Clay Ceramics Manufacturing. These amendments make two technical corrections to...

  20. Experimental study of Human Adenoviruses interactions with clays

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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.

  2. Adsorption of diethyl phthalate ester to clay minerals.

    Science.gov (United States)

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

    2015-01-01

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

  3. Adsorption of zinc and lead on clay minerals

    Directory of Open Access Journals (Sweden)

    Katarína Jablonovská

    2006-12-01

    Full Text Available Clays (especially bentonite, zeolite and quartz sand are widely used as landfill barriers to prevent contamination of subsoil and groundwater by leachates containing heavy metals. The sorption of zinc and lead on these clays was studied as a function of time and it was found that the initial 1 h our was sufficient to exchange most of the metal ions. The retention efficiency of clay samples of Zn2+ and Pb2+ follows the order of bentonite > zeolite> quartz sand. Whatever the clay sample, lead is retained more than zinc. The concentration of elements in the solution was followed by atomic adsorption spectrofotometry. Bacillus cereus and Bacillus pumilus, previously isolated from the kaoline deposit Horna Prievrana was added into the clay samples to comparise the accumulation of Zn2+ and Pb2+ from the model solution. The study of heavy metal adsorption capacity of bacteria- enriched clay adsorbent showed a high retention efficiency for lead ions as comparised with zinc ions. Biosorption is considered a potential instrument for the removal of metals from waste solutions and for the precious metals recovery as an alternative to the conventional processes.

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

    Science.gov (United States)

    Kohut, Connie K.; And Others

    1993-01-01

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

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

    Science.gov (United States)

    Kohut, Connie K.; And Others

    1993-01-01

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

  6. Lead removal from aqueous solutions by a Tunisian smectitic clay.

    Science.gov (United States)

    Chaari, Islem; Fakhfakh, Emna; Chakroun, Salima; Bouzid, Jalel; Boujelben, Nesrine; Feki, Mongi; Rocha, Fernando; Jamoussi, Fakher

    2008-08-15

    The adsorption of Pb(2+) ions onto Tunisian smectite-rich clay in aqueous solution was studied in a batch system. Four samples of clay (AYD, AYDh, AYDs, AYDc) were used. The raw AYD clay was sampled in the Coniacian-Early Campanian of Jebel Aïdoudi in El Hamma area (South of Tunisia). AYDh and AYDs corresponds to AYD activated by 2.5 mol/l hydrochloric acid and 2.5 mol/l sulphuric acid, respectively. AYDc corresponds to AYD calcined at different temperatures (100, 200, 300, 400, 500 and 600 degrees C). The raw AYD clay was characterized by X-ray diffraction, chemical analysis, infrared spectroscopy and coupled DTA-TGA. Specific surface area of all the clay samples was determined from nitrogen adsorption isotherms. Preliminary adsorption tests showed that sulphuric acid and hydrochloric acid activation of raw AYD clay enhanced its adsorption capacity for Pb(2+) ions. However, the uptake of Pb(2+) by AYDs was very high compared to that by AYDh. This fact was attributed to the greater solubility of clay minerals in sulphuric acid compared to hydrochloric acid. Thermic activation of AYD clay reduced the Pb(2+) uptake as soon as calcination temperature reaches 200 degrees C. All these preliminary results were well correlated to the variation of the specific surface area of the clay samples. The ability of AYDs sample to remove Pb(2+) from aqueous solutions has been studied at different operating conditions: contact time, adsorbent amount, metal ion concentration and pH. Kinetic experiments showed that the sorption of lead ions on AYDs was very fast and the equilibrium was practically reached after only 20 min. The results revealed also that the adsorption of lead increases with an increase in the solution pH from 1 to 4.5 and then decreases, slightly between pH 4.5 and 6, and rapidly at pH 6.5 due to the precipitation of some Pb(2+) ions. The equilibrium data were analysed using Langmuir isotherm model. The maximum adsorption capacity (Q(0)) increased from 25 to 25

  7. Synthesis and characterization of nanocomposites based on polyurethane in aqueous dispersions with non-modified hydrophilic clays; Sintese e caracterizacao de nanocompositos a base de poliuretanos em dispersoes aquosas com argilas hidrofilicas nao-modificadas

    Energy Technology Data Exchange (ETDEWEB)

    Miranda, G.S.; Delpechi, M.C.; Santo, W.L.E., E-mail: mcd@uerj.b [Universidade do Estado do Rio de Janeiro (UERJ), RJ (Brazil)

    2010-07-01

    Several studies involving the formation of polyurethane nanocomposites employing clays of montmorillonite modified. This involves the presence of quaternary ammonium salts, the cation exchange needed to increase the interlayer space of clays that incorporate more than one step to the process, generates a higher cost. In this paper the synthesis of nanocomposite polyurethanes dispersed in water allowed not only the production of materials less harmful to the environment, but also the incorporation of hydrophilic clays, calcium and sodium in nature, without any modifications. Dispersions produced from 0.5, 1.0 and 2.5% clay (on the mass of prepolymer) were characterized in terms of total solids content, the films obtained by casting were evaluated for adhesiveness, diffraction X-rays, scanning electron microscopy. Most systems showed intercalated and partially exfoliated structures. (author)

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

    Science.gov (United States)

    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.

  9. The composition and origin of Ghana medicine clays.

    Science.gov (United States)

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

    2011-08-01

    The mineral, organic and elemental composition of medicine clays from three shrines in the Tong Hills in northern Ghana (Gbankil, Kusanaab, and Yaane) are assessed to ascertain what additives they might contain and the implications for their recognition, for example in archaeological contexts. These are clays that are widely used for healing purposes being perceived efficacious in curing multiple ailments and which are given a divine provenance, but their collection is ascribed human agency. The Yaane clay is also supplied as part of the process of obtaining the right to operate the shrine elsewhere making it widely dispersed. Organic geochemical analyses revealed a predominance of plant-derived material with a substantial contribution of microbial origin. Based on these (supported by elemental and mineral analyses), no unnatural organic material could be detected, making an exogenous contribution to these clays unlikely. The implications are that these are wholly natural medicinal substances with no anthropogenic input into their preparation, as the traditions suggest. The very similar mineralogy of all the clays, including a non-medicine clay sampled, suggests that, unless the geology radically differed, differentiating between them analytically in an archaeological contexts would be doubtful.

  10. Boron enrichment in martian clay.

    Directory of Open Access Journals (Sweden)

    James D Stephenson

    Full Text Available We have detected a concentration of boron in martian clay far in excess of that in any previously reported extra-terrestrial object. This enrichment indicates that the chemistry necessary for the formation of ribose, a key component of RNA, could have existed on Mars since the formation of early clay deposits, contemporary to the emergence of life on Earth. Given the greater similarity of Earth and Mars early in their geological history, and the extensive disruption of Earth's earliest mineralogy by plate tectonics, we suggest that the conditions for prebiotic ribose synthesis may be better understood by further Mars exploration.

  11. Boron Enrichment in Martian Clay

    Science.gov (United States)

    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

  12. Strength Properties of Aalborg Clay

    DEFF Research Database (Denmark)

    Iversen, Kirsten Malte; Nielsen, Benjaminn Nordahl; Augustesen, Anders Hust

    resulted in many damaged buildings in Aalborg. To provide sufficient bearing capacity it is therefore necessary either to remove the fill or to construct the building on piles. Both methods imply that the strength of Aalborg Clay is important for the construction. This paper evaluates the strength...... of Aalborg Clay by use of triaxial tests from four different locations. Both the drained strength (c and ϕ) and the undrained strength (cu) are assessed through two different methods: one where the strength is assumed to vary with the effective stress and another where the strength is found to be constant....

  13. Hollow clay tile wall program summary report

    Energy Technology Data Exchange (ETDEWEB)

    Henderson, R.C.; Jones, W.D. [Gilbert/Commonwealth, Inc., Oak Ridge, TN (United States); Beavers, J.E. [MS Technology, Inc. (United States)

    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?

  14. Clay membrane made of natural high plasticity clay

    DEFF Research Database (Denmark)

    Foged, Niels; Baumann, Jens

    1998-01-01

    Leachate containment in Denmark has through years been regulated by the DIF Recommendation for Sanitary Landfill Liners (DS/R 466). It states natural clay deposits may be used for membrane material provided the membrane and drainage system may contain at least 95% of all leachate created throughout...

  15. 超固结土模型平面应变分叉理论解与数值模拟%Analytical Solution and Numerical Simulation for Plane Strain Bifurcation in Constitutive Model for Over-Consolidated Clays

    Institute of Scientific and Technical Information of China (English)

    孙德安; 段博; 甄文战

    2011-01-01

    应变局部化理论最基本的问题在于局部化分叉产生的条件.针对基于伏斯列夫面超固结黏土三维弹塑性本构模型,推导平面应变条件下局部化分叉理论解及因局部化分叉而产生的剪切带倾角的表达式,并分析不同超固结比对局部化分叉理论解和剪切带倾角的影响.理论分析表明,在平面应变条件下,土体局部化分叉出现在应力应变硬化阶段,剪切带倾角在分叉前随着应变局部化的扩张发生显著变化,在分叉后趋于稳定.最后,利用非线性有限元软件ABAQUS,在平面应变应力路径下对均匀各向同性多单元立方体局部化分叉现象进行数值分析,得出的局部化分叉数值解与理论解较为一致,验证了理论解的可靠性.%A fundamental problem concerning the theory of strain localization is the condition of the occurrence of localization bifurcation.Based on the Hvorslev envelope-based three-dimensional elastoplastic constitutive model for over-consolidated clay, an analytical solution of bifurcation and the expression of inclination angle for shear band caused by localization bifurcation are derived for strain localization in plane strain stress states.Meanwhile, influences of over-consolidation ratio (OCR) on the analytical solution and the inclination angle are analyzed.The theoretical analysis shows that onset of localization bifurcation occurs in the hardening regime under the plane strain conditions and, with strain localization expanding, the change in inclination angle of shear band is striking before bifurcation and steady thereafter.On the other hand, numerical simulation of plane strain tests on the isotropically homogenous cubic specimen for the bifurcation is carried out by using a finite element analysis software ABAQUS with the model implemented.Numerical solutions exhibit a good overall agreement with analytical solutions for the bifurcation onset, indicating that the analytical solutions are

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

    Science.gov (United States)

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

    2007-05-01

    . The speciation of the Cu-ligand complex was found to be different, in bulk water (Hureau et al., 2006) and in clay suspensions, where n increases. This new speciation of the copper metal ions, used as a molecular probe, allows to "measure" the pH of interlayer water which is shown to be significantly lower than in bulk water pH. Molecular models for PrP attachment to the clay basal plane and Sm location within the clay interlayer were obtained by MD computations. Implications on PrP pathogenicity, following carcase burial and particle ingestions, and on radionuclide mobility, following nuclear waste burial in clay rich repository sites, will be discussed.

  17. Clay minerals, metallic oxides and oxy-hydroxides and soil organic carbon distribution within soil aggregates in temperate forest soils

    Science.gov (United States)

    Gartzia-Bengoetxea, Nahia; Fernández-Ugalde, Oihane; Virto, Iñigo; Arias-González, Ander

    2017-04-01

    Soil mineralogy is of primary importance for key environmental services provided by soils like carbon sequestration. However, current knowledge on the effects of clay mineralogy on soil organic carbon (SOC) stabilization is based on limited and conflicting data. In this study, we investigated the relationship between clay minerals, metallic oxides and oxy-hydroxides and SOC distribution within soil aggregates in mature Pinus radiata D.Don forest plantations. Nine forest stands located in the same geographical area of the Basque Country (North of Spain) were selected. These stands were planted on different parent material (3 on each of the following: sandstone, basalt and trachyte). There were no significant differences in climate and forest management among them. Moreover, soils under these plantations presented similar content of clay particles. We determined bulk SOC storage, clay mineralogy, the content of Fe-Si-Al-oxides and oxyhydroxides and the distribution of organic C in different soil aggregate sizes at different soil depths (0-5 cm and 5-20 cm). The relationship between SOC and abiotic factors was investigated using a factor analysis (PCA) followed by stepwise regression analysis. Soils developed on sandstone showed significantly lower concentration of SOC (29 g C kg-1) than soils developed on basalts (97 g C kg-1) and trachytes (119 g C kg-1). The soils on sandstone presented a mixed clay mineralogy dominated by illite, with lesser amounts of hydroxivermiculite, hydrobiotite and kaolinite, and a total absence of interstratified chlorite/vermiculite. In contrast, the major crystalline clay mineral identified in the soils developed on volcanic rocks was interstratified chlorite/vermiculite. Nevertheless, no major differences were observed between basaltic and trachytic soils in the clay mineralogy. The selective extraction of Fe showed that the oxalate extractable iron was significantly lower in soils on sandstone (3.7%) than on basalts (11.2%) and

  18. Cluster Based Text Classification Model

    DEFF Research Database (Denmark)

    2011-01-01

    We propose a cluster based classification model for suspicious email detection and other text classification tasks. The text classification tasks comprise many training examples that require a complex classification model. Using clusters for classification makes the model simpler and increases th...... datasets. Our model also outperforms A Decision Cluster Classification (ADCC) and the Decision Cluster Forest Classification (DCFC) models on the Reuters-21578 dataset....

  19. To what extent clay mineralogy affects soil aggregation? Consequences for soil organic matter stabilization

    Science.gov (United States)

    Fernandez-Ugalde, O.; Barré, P.; Hubert, F.; Virto, I.; Chenu, C.; Ferrage, E.; Caner, L.

    2012-12-01

    Aggregation is a key process for soil functioning as it influences C storage, vulnerability to erosion and water holding capacity. While the influence of soil organic C on aggregation has been documented, much less is known about the role of soil mineralogy. Soils usually contain a mixture of clay minerals with contrasted surface properties, which should result on different abilities of clay minerals to aggregation. We took advantage of the intrinsic mineral heterogeneity of a temperate Luvisol to compare the role of clay minerals (illite, smectite, kaolinite, and mixed-layer illite-smectite) in aggregation. In a first step, grassland and tilled soil samples were fractionated in water in aggregate-size classes according to the hierarchical model of aggregation (Tisdall and Oades, 1982). Clay mineralogy and organic C in the aggregate-size classes were analyzed. The results showed that interstratified minerals containing swelling phases accumulated in aggregated fractions (>2 μm) compared to free clay fractions (500 μm) to micro-aggregates (50-250 μm). C concentration and C/N ratio followed the opposite trend. These results constitute a clay mineral-based evidence for the hierarchical model of aggregation, which postulates an increasing importance of the reactivity of clay minerals in the formation of micro-aggregates compared to larger aggregates. In the latter aggregates, formation relies on the physical enmeshment of particles by fungal hyphae, and root and microbial exudates. In a second step, micro-aggregates from the tilled soil samples were submitted to increasingly disaggregating treatments by sonication to evaluate the link between their water stability and clay mineralogy. Micro-aggregates with increasing stability showed an increase of interstratified minerals containing swelling phases and C concentration for low intensities of disaggregation (from 0 to 5 J mL-1). This suggests that swelling phases promote their stability. Swelling phases and organic C

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

    Science.gov (United States)

    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.

  1. 解析一款新型光束电脑灯--Clay Paky Sharpy Wash 330%Clay Paky Sharpy Wash 330

    Institute of Scientific and Technical Information of China (English)

    迈克·伍德[美; 姚涵春(译)

    2014-01-01

    According to the test , the composition, properties and characteristics of the new type beam light Clay Paky Sharpy Wash 330 were analyzed based on the test.%通过测试,解析一款新型光束电脑灯Clay Paky Sharpy Wash 330的构成、性能及特点。

  2. Method for gesture based modeling

    DEFF Research Database (Denmark)

    2006-01-01

    A computer program based method is described for creating models using gestures. On an input device, such as an electronic whiteboard, a user draws a gesture which is recognized by a computer program and interpreted relative to a predetermined meta-model. Based on the interpretation, an algorithm...... is assigned to the gesture drawn by the user. The executed algorithm may, for example, consist in creating a new model element, modifying an existing model element, or deleting an existing model element....

  3. Property and performance amelioration of pelagic clay from the East Pacific

    Institute of Scientific and Technical Information of China (English)

    Peiping ZHANG; Shufeng LIU; Xuefa SHI; Huahua LU; Juanjuan LIU; Xiaoguo CHI

    2008-01-01

    To make use of the pelagic clay as polymer filling, the properties of clay sediments from the ocean investigation zone of China in the East Pacific were studied by the SSA, XRF, ICP/MAS, FHR, XRD, SEM, DTA/TG and granularity distributing etc. , and experiments were settled to improve the whiteness and activation of the clay based on these data. Compared with land clay, pelagic clay holds many particular features, such as fine particles and incompact accumulation, worse crystallization and more defects, high activity, complex mineral and chemical components, and low whiteness etc. Processing the purified pelagic clay with acids and zinc, then baked it at different temperatures, the whiteness of clay can be increased from 23.8% to 73.1%, and the optimized conditions is : consistency of vitriol 25%, ratio of clay to water 4:1, reaction time 4h, reaction temperature 90℃, dosage of zinc 2.0 g/L, and baking temperature 700℃. And the SSA of whited clay is increased too. Using the dry milling method to modify the pelagic clay with organic reagents, the optimized technique is KH550, concentration 1.5%, reaction time 20 min. XRD,FTIR and SEM testing indicate that the mechanism of organic activation was mainly surface absorbing and chemical combination secondly.

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

    Science.gov (United States)

    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.

  5. Picasso Masks: Cubism in Clay

    Science.gov (United States)

    Daddino, Michelle

    2010-01-01

    This article describes an art project developed by the author which provides a way to further the children's understanding of Picasso's Cubism style in 3-D. Through this project, upper-elementary students learn a bit about the life and art of Picasso as they gain a firm understanding of the style of art known as Cubism, and apply clay techniques…

  6. ADSORPTION OF SURFACTANT ON CLAYS

    Science.gov (United States)

    Surfactants used to enhance remediation of soils by soil washing are often lost in the process. Neither the amount nor the cause of this loss is known. It is assumed that clays present in the soil are responsible for the loss of the surfactant. In this papere, adsorption prope...

  7. Geotechnical properties of Karwar marine clay

    Digital Repository Service at National Institute of Oceanography (India)

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

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

  8. Investigation of structure and properties of novel multi-layer clay nanocomposite films produced controllably by continuous chaotic advection blending

    Science.gov (United States)

    Mahesha, Chaitra

    A unique processing technique based on chaotic advection developed at Clemson University and shown to controllably produce structured materials in the past was employed to produce structured nanocomposites with a high degree of clay orientation as well as localization of platelets within layers of nanoscale thicknesses. Continuous lengths of nanocomposites with different clay contents were extruded in the form of films by feeding separately melts of virgin polyamide-6 polymer and polyamide 6-clay masterbatch into a continuous chaotic advection blender. A variety of composite structures were producible at fixed clay compositions. The internal structure was characterized by transmission electron microscopy (TEM), x-ray diffraction (XRD) and differential scanning calorimetry (DSC). Nanocomposites with novel in-situ multi-layered structures and a high degree of platelet orientation were formed by the recursive stretching and folding of the melt domains due to chaotic advection. Clay platelets were localized within discrete regions to form alternating virgin and platelet-rich layers leading to a hierarchical structure with multiple nano-scales. The thicknesses of the layers reduced with prolonged chaotic advection, eventually leading to nanocomposites in which the multi-layering was no longer discernible. The oriented platelets appeared to be homogenously dispersed through the bulk of the nanocomposite. Investigation of the morphology of the matrix by XRD showed that the homogeneity of the crystalline phase and the orientation of polymer chains parallel to the film surface increased with increased chaotic advection. Also, as the layer thickness reduced, the number of polymer chains restricted by clay platelets increased causing the gamma-crystalline fraction to increase. While XRD results suggested a change in total crystallinity with chaotic advection and clay content but without a specific trend, no change in crystallinity was measured by DSC. Such contradictions are

  9. CMC use as colloid protector in water and clay basis drilling fluids: part II; Uso do CMC como coloide protetor em fluidos de perfuracao a base de agua e argilas: parte II

    Energy Technology Data Exchange (ETDEWEB)

    Amorim, Luciana Viana [Universidade Federal, Campina Grande, PB (Brazil). Engenharia de Processos]. E-mail: lucianaa@labdes.ufpb.br; Viana, Josiane Dantas; Farias, Kassie Vieira; Lira, Helio de Lucena; Ferreira, Heber Carlos [Universidade Federal, Campina Grande, PB (Brazil). Dept. de Engenharia de Materiais]. E-mail: josianedantas@bol.com.br; kassievieira@bol.com.br; helio@dema.ufpb.br; heber@dema.ufpb.br; Franca, Kepler Borges [Universidade Federal, Campina Grande, PB (Brazil). Dept. de Eng. Quimica]. E-mail: kepler@labdes.ufpb.br

    2003-07-01

    The aim of this work is to study the protect effect of the low viscosity carboxymethyl cellulose (CMC) on water based oil well drilling fluids and bentonite clays treated with sodium, additivated with degrading agents. The drilling fluids were prepared with a concentration of 4.86% w/w, according to PETROBRAS norms. It was studied three samples of natural bentonite clays treated with Na{sub 2}CO{sub 3}, from Boa Vista, PB. The drilling fluids were treated with three different concentration of CMC and submitted to a cure for a period of 24 hours. After it were added degrading agents (CaCl{sub 2} + MgCl{sub 2}). Also, it was done the treatment in a reverse order, i.e., first the drilling fluids were treated with degrading agents and after with CMC. It was measured apparent viscosity (AV), plastic viscosity (PV) by using a Fann Viscosimeter and water loss (WL), by using a Fann filter press. The results showed that CMC protect the drilling fluids from the flocculating effect of calcium and magnesium and stop the damage caused by degrading agents. Also, the order of the treatment (degrading agent - CMC) does not present significant influence in the rheological properties of the studied drilling fluids. (author)

  10. Reactive transport simulations of the evolution of a cementitious repository in clay-rich host rocks

    Science.gov (United States)

    Kosakowski, Georg; Berner, Urs; Kulik, Dmitrii A.

    2010-05-01

    In Switzerland, the deep geological disposal in clay-rich rocks is foreseen not only for high-level radioactive waste, but also for intermediate-level (ILW) and low-level (LLW) radioactive waste. Typically, ILW and LLW repositories contain huge amounts of cementitious materials used for waste conditioning, confinement, and as backfill for the emplacement caverns. We are investigating the interactions of such a repository with the surrounding clay rocks and with other clay-rich materials such as sand/bentonite mixtures that are foreseen for backfilling the access tunnels. With the help of a numerical reactive transport model, we are comparing the evolution of cement/clay interfaces for different geochemical and transport conditions. In this work, the reactive transport of chemical components is simulated with the multi-component reactive transport code OpenGeoSys-GEM. It employs the sequential non-iterative approach to couple the mass transport code OpenGeoSys (http://www.ufz.de/index.php?en=18345) with the GEMIPM2K (http://gems.web.psi.ch/) code for thermodynamic modeling of aquatic geochemical systems which is using the Gibbs Energy Minimization (GEM) method. Details regarding code development and verification can be found in Shao et al. (2009). The mineral composition and the pore solution of a CEM I 52.5 N HTS hydrated cement as described by Lothenbach & Wieland (2006) are used as an initial state of the cement compartment. The setup is based on the most recent CEMDATA07 thermodynamic database which includes several ideal solid solutions for hydrated cement minerals and is consistent with the Nagra/PSI thermodynamic database 01/01. The smectite/montmorillonite model includes cation exchange processes and amphotheric≡SOH sites and was calibrated on the basis of data by Bradbury & Baeyens (2002). In other reactive transport codes based on the Law of Mass Action (LMA) for solving geochemical equilibria, cation exchange processes are usually calculated assuming

  11. An Experimental study of the initial volumetric strain rate effect on the creep behaviour of reconstituted clays

    Science.gov (United States)

    Bagheri, M.; Rezania, M.; Nezhad, M. M.

    2015-09-01

    Clayey soils tend to undergo continuous compression with time, even after excess pore pressures have substantially dissipated. The effect of time on deformation and mechanical response of these soft soils has been the subject of numerous studies. Based on these studies, the observed time-dependent behaviour of clays is mainly related to the evolution of soil volume and strength characteristics with time, which are classified as creep and/or relaxation properties of the soil. Apart from many empirical relationships that have been proposed in the literature to capture the rheological behaviour of clays, a number of viscid constitutive relationships have also been developed which have more attractive theoretical attributes. A particular feature of these viscid models is that their creep parameters often have clear physical meaning (e.g. coefficient of secondary compression, Cα). Sometimes with these models, a parameter referred to as initial/reference volumetric strain rate, has also been alluded as a model parameter. However, unlike Cα, the determination of and its variations with stress level is not properly documented in the literature. In an attempt to better understand , this paper presents an experimental investigation of the reference volumetric strain rate in reconstituted clay specimens. A long-term triaxial creep test, at different shear stress levels and different strain rates, was performed on clay specimen whereby the volumetric strain rate was measured. The obtained results indicated the stress-level dependency and non-linear variation of with time.

  12. Studies on Effective Elastic Properties of CNT/Nano-Clay Reinforced Polymer Hybrid Composite

    Science.gov (United States)

    Thakur, Arvind Kumar; Kumar, Puneet; Srinivas, J.

    2016-02-01

    This paper presents a computational approach to predict elastic propertiesof hybrid nanocomposite material prepared by adding nano-clayplatelets to conventional CNT-reinforced epoxy system. In comparison to polymers alone/single-fiber reinforced polymers, if an additional fiber is added to the composite structure, it was found a drastic improvement in resultant properties. In this regard, effective elastic moduli of a hybrid nano composite are determined by using finite element (FE) model with square representative volume element (RVE). Continuum mechanics based homogenization of the nano-filler reinforced composite is considered for evaluating the volumetric average of the stresses and the strains under different periodic boundary conditions.A three phase Halpin-Tsai approach is selected to obtain the analytical result based on micromechanical modeling. The effect of the volume fractions of CNTs and nano-clay platelets on the mechanical behavior is studied. Two different RVEs of nano-clay platelets were used to investigate the influence of nano-filler geometry on composite properties. The combination of high aspect ratio of CNTs and larger surface area of clay platelets contribute to the stiffening effect of the hybrid samples. Results of analysis are validated with Halpin-Tsai empirical formulae.

  13. Model Construct Based Enterprise Model Architecture and Its Modeling Approach

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    In order to support enterprise integration, a kind of model construct based enterprise model architecture and its modeling approach are studied in this paper. First, the structural makeup and internal relationships of enterprise model architecture are discussed. Then, the concept of reusable model construct (MC) which belongs to the control view and can help to derive other views is proposed. The modeling approach based on model construct consists of three steps, reference model architecture synthesis, enterprise model customization, system design and implementation. According to MC based modeling approach a case study with the background of one-kind-product machinery manufacturing enterprises is illustrated. It is shown that proposal model construct based enterprise model architecture and modeling approach are practical and efficient.

  14. 21 CFR 186.1256 - Clay (kaolin).

    Science.gov (United States)

    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) contain...

  15. HMM-based Trust Model

    DEFF Research Database (Denmark)

    ElSalamouny, Ehab; Nielsen, Mogens; Sassone, Vladimiro

    2010-01-01

    with their dynamic behaviour. Using Hidden Markov Models (HMMs) for both modelling and approximating the behaviours of principals, we introduce the HMM-based trust model as a new approach to evaluating trust in systems exhibiting dynamic behaviour. This model avoids the fixed behaviour assumption which is considered...... the major limitation of existing Beta trust model. We show the consistency of the HMM-based trust model and contrast it against the well known Beta trust model with the decay principle in terms of the estimation precision....

  16. Adsorption of ethyl acetate onto modified clays and its regeneration with supercritical CO2

    Directory of Open Access Journals (Sweden)

    A. M. Cavalcante

    2005-03-01

    Full Text Available Modified clays were used to remove ethyl acetate from aqueous solutions. These clays were regenerated using supercritical CO2. Structural changes in the montmorillonite clay after treatment with quaternary amines were studied. The surface properties of the modified clay changed from highly hydrophilic to highly organophilic. The clay was regenerated by percolation of a stream of CO2 through the porous montmorillonite matrix. Different pressures and temperatures were employed, resulting in different fluid conditions (gas, liquid, and supercritical. The experimental data was fitted with a simplified model. The best desorption result was found under supercritical conditions. A crossover effect was observed. The capacity of the modified clay as a pollutant attenuator remained almost unchanged after a regeneration cycle.

  17. Model-Based Reasoning

    Science.gov (United States)

    Ifenthaler, Dirk; Seel, Norbert M.

    2013-01-01

    In this paper, there will be a particular focus on mental models and their application to inductive reasoning within the realm of instruction. A basic assumption of this study is the observation that the construction of mental models and related reasoning is a slowly developing capability of cognitive systems that emerges effectively with proper…

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

    Science.gov (United States)

    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…

  19. Clay & Children: More than Making Pots.

    Science.gov (United States)

    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…

  20. Improving the Hydraulic Performance of Stormwater Infiltration Systems in Clay Tills

    DEFF Research Database (Denmark)

    Bockhorn, Britta

    D study was initiated with the objective to test and evaluate if the hydraulic performance of stormwater infiltration systems can be significantly improved if the site-specific geological heterogeneity is incorporated into the design and siting of such systems. The assessment is based on different field...... infiltration systems. Models employing standard soil physical parameters should be used with care as they do not always realistically describe site-specific hydrologic properties. A fourth study showed that the hydraulic performance of infiltration trenches was increased by a factor of two, when spear auger......Many cities of the Northern Hemisphere are covered by low permeable clay tills, which pose a challenge for stormwater infiltration practices. However, clay tills are amongst the most heterogeneous types of sediments and hydraulic conductivities can vary by several orders of magnitude. This Ph...

  1. Parametric studies on effective elastic modulus of nano-clay/polymer composites

    Science.gov (United States)

    Thakur, Arvind Kumar; Srinivas, J.

    2016-04-01

    This paper proposes a methodology of finding effective elastic properties of nanoclay-reinforced polymer composites with aligned clay particles. When interphase regions exist between nanoclay platelets and polymer, numerical homogenization is initially required to identify the properties of effective particle consisting of both clay and interface regions. Once the elastic properties of equivalent particle are obtained, Mori-Tanaka approach is employed to identify all the effective properties of resultant composite. The methodology is implemented with a modular based computer program developed in MATLAB and the variation of longitudinal modulus as a function of weight fraction of nanoclay, aspect ratio of fibers, number of stacks, nanoclay volume fraction etc is reported. The empirical results are validated with a numerical model developed in ANSYS using a representative volume element for prediction of the elastic modulus. Results are illustrated with two cases of exfoliated morphology.

  2. Reconstructing a hydrogen-driven microbial metabolic network in Opalinus Clay rock

    Science.gov (United States)

    Bagnoud, Alexandre; Chourey, Karuna; Hettich, Robert L.; de Bruijn, Ino; Andersson, Anders F.; Leupin, Olivier X.; Schwyn, Bernhard; Bernier-Latmani, Rizlan

    2016-01-01

    The Opalinus Clay formation will host geological nuclear waste repositories in Switzerland. It is expected that gas pressure will build-up due to hydrogen production from steel corrosion, jeopardizing the integrity of the engineered barriers. In an in situ experiment located in the Mont Terri Underground Rock Laboratory, we demonstrate that hydrogen is consumed by microorganisms, fuelling a microbial community. Metagenomic binning and metaproteomic analysis of this deep subsurface community reveals a carbon cycle driven by autotrophic hydrogen oxidizers belonging to novel genera. Necromass is then processed by fermenters, followed by complete oxidation to carbon dioxide by heterotrophic sulfate-reducing bacteria, which closes the cycle. This microbial metabolic web can be integrated in the design of geological repositories to reduce pressure build-up. This study shows that Opalinus Clay harbours the potential for chemolithoautotrophic-based system, and provides a model of microbial carbon cycle in deep subsurface environments where hydrogen and sulfate are present. PMID:27739431

  3. Reconstructing a hydrogen-driven microbial metabolic network in Opalinus Clay rock

    Science.gov (United States)

    Bagnoud, Alexandre; Chourey, Karuna; Hettich, Robert L.; de Bruijn, Ino; Andersson, Anders F.; Leupin, Olivier X.; Schwyn, Bernhard; Bernier-Latmani, Rizlan

    2016-10-01

    The Opalinus Clay formation will host geological nuclear waste repositories in Switzerland. It is expected that gas pressure will build-up due to hydrogen production from steel corrosion, jeopardizing the integrity of the engineered barriers. In an in situ experiment located in the Mont Terri Underground Rock Laboratory, we demonstrate that hydrogen is consumed by microorganisms, fuelling a microbial community. Metagenomic binning and metaproteomic analysis of this deep subsurface community reveals a carbon cycle driven by autotrophic hydrogen oxidizers belonging to novel genera. Necromass is then processed by fermenters, followed by complete oxidation to carbon dioxide by heterotrophic sulfate-reducing bacteria, which closes the cycle. This microbial metabolic web can be integrated in the design of geological repositories to reduce pressure build-up. This study shows that Opalinus Clay harbours the potential for chemolithoautotrophic-based system, and provides a model of microbial carbon cycle in deep subsurface environments where hydrogen and sulfate are present.

  4. Reconstructing a hydrogen-driven microbial metabolic network in Opalinus Clay rock.

    Science.gov (United States)

    Bagnoud, Alexandre; Chourey, Karuna; Hettich, Robert L; de Bruijn, Ino; Andersson, Anders F; Leupin, Olivier X; Schwyn, Bernhard; Bernier-Latmani, Rizlan

    2016-10-14

    The Opalinus Clay formation will host geological nuclear waste repositories in Switzerland. It is expected that gas pressure will build-up due to hydrogen production from steel corrosion, jeopardizing the integrity of the engineered barriers. In an in situ experiment located in the Mont Terri Underground Rock Laboratory, we demonstrate that hydrogen is consumed by microorganisms, fuelling a microbial community. Metagenomic binning and metaproteomic analysis of this deep subsurface community reveals a carbon cycle driven by autotrophic hydrogen oxidizers belonging to novel genera. Necromass is then processed by fermenters, followed by complete oxidation to carbon dioxide by heterotrophic sulfate-reducing bacteria, which closes the cycle. This microbial metabolic web can be integrated in the design of geological repositories to reduce pressure build-up. This study shows that Opalinus Clay harbours the potential for chemolithoautotrophic-based system, and provides a model of microbial carbon cycle in deep subsurface environments where hydrogen and sulfate are present.

  5. Model-based Software Engineering

    DEFF Research Database (Denmark)

    2010-01-01

    The vision of model-based software engineering is to make models the main focus of software development and to automatically generate software from these models. Part of that idea works already today. But, there are still difficulties when it comes to behaviour. Actually, there is no lack in models...

  6. Model-based Software Engineering

    DEFF Research Database (Denmark)

    2010-01-01

    The vision of model-based software engineering is to make models the main focus of software development and to automatically generate software from these models. Part of that idea works already today. But, there are still difficulties when it comes to behaviour. Actually, there is no lack in models...

  7. Principles of models based engineering

    Energy Technology Data Exchange (ETDEWEB)

    Dolin, R.M.; Hefele, J.

    1996-11-01

    This report describes a Models Based Engineering (MBE) philosophy and implementation strategy that has been developed at Los Alamos National Laboratory`s Center for Advanced Engineering Technology. A major theme in this discussion is that models based engineering is an information management technology enabling the development of information driven engineering. Unlike other information management technologies, models based engineering encompasses the breadth of engineering information, from design intent through product definition to consumer application.

  8. Experimental study on the stability of plate anchors in clay under cyclic loading

    Directory of Open Access Journals (Sweden)

    Long Yu

    2015-03-01

    Full Text Available Although the bearing capacity of plate anchors in clay has been studied extensively, the results considering the effects of offshore cyclic loading are relatively rare. In the present study, 1 g model tests are carried out to investigate the effect of cyclic loading on the bearing capacity of plate anchors in clay. The ultimate pullout capacity of plate anchors in clay decreases as the accumulated plastic shear strain grows due to the strain-softening of clay under cyclic loading. The load–displacement curves of these tests are presented and the effects of overburden stress and cyclic loading amplitude on the strain-softening behavior are discussed.

  9. Enhancement of corrosion protection effect in mechanochemically synthesized Polyaniline/MMT clay nanocomposites

    Directory of Open Access Journals (Sweden)

    N. Kalaivasan

    2017-02-01

    Full Text Available Nanocomposite material that consists of DBSA (dodecylbenzensulfonic acid doped polyaniline (PANI was prepared by solvent free mechanochemical intercalation method. Organic aniline monomer was first intercalated into the interlayer regions of Na-MMT (sodium montmorillonite clay hosts and followed by one-step oxidative polymerization. The as synthesized polyaniline clay nanocomposites were treated with DBSA to get PANI-DBSA clay nanocomposites. PANI-DBSA clay nanocomposites in the form of coatings at different concentrations of DBSA on C45 steel were found much superior in corrosion protection over those of conventional polyaniline, based on the series of electrochemical measurement of corrosion potential, polarization resistance and corrosion current in 3.5% aqueous NaCl electrolyte. UV–visible spectroscopy, FT-IR and SEM studies confirm the formation of intercalated polyaniline clay nanocomposites inside the clay nanolayers.

  10. Element-Based Computational Model

    Directory of Open Access Journals (Sweden)

    Conrad Mueller

    2012-02-01

    Full Text Available A variation on the data-flow model is proposed to use for developing parallel architectures. While the model is a data driven model it has significant differences to the data-flow model. The proposed model has an evaluation cycleof processing elements (encapsulated data that is similar to the instruction cycle of the von Neumann model. The elements contain the information required to process them. The model is inherently parallel. An emulation of the model has been implemented. The objective of this paper is to motivate support for taking the research further. Using matrix multiplication as a case study, the element/data-flow based model is compared with the instruction-based model. This is done using complexity analysis followed by empirical testing to verify this analysis. The positive results are given as motivation for the research to be taken to the next stage - that is, implementing the model using FPGAs.

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

    Science.gov (United States)

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

    2013-03-01

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

  12. Thermal conductivity of unsaturated clay-rocks

    Directory of Open Access Journals (Sweden)

    D. Jougnot

    2010-01-01

    Full Text Available The parameters used to describe the electrical conductivity of a porous material can be used to describe also its thermal conductivity. A new relationship is developed to connect the thermal conductivity of an unsaturated porous material to the thermal conductivity of the different phases of the composite, and two electrical parameters called the first and second Archie's exponents. A good agreement is obtained between the new model and thermal conductivity measurements performed using packs of glass beads and core samples of the Callovo-Oxfordian clay-rocks at different saturations of the water phase. We showed that the three model parameters optimised to fit the new model against experimental data (namely the thermal conductivity of the solid phase and the two Archie's exponents are consistent with independent estimates. We also observed that the anisotropy of the effective thermal conductivity of the Callovo-Oxfordian clay-rock was mainly due to the anisotropy of the thermal conductivity of the solid phase.

  13. Graph Model Based Indoor Tracking

    DEFF Research Database (Denmark)

    Jensen, Christian Søndergaard; Lu, Hua; Yang, Bin

    2009-01-01

    infrastructure for different symbolic positioning technologies, e.g., Bluetooth and RFID. More specifically, the paper proposes a model of indoor space that comprises a base graph and mappings that represent the topology of indoor space at different levels. The resulting model can be used for one or several...... indoor positioning technologies. Focusing on RFID-based positioning, an RFID specific reader deployment graph model is built from the base graph model. This model is then used in several algorithms for constructing and refining trajectories from raw RFID readings. Empirical studies with implementations...

  14. Micromechanical Properties of Nanostructured Clay-Oxide Multilayers Synthesized by Layer-by-Layer Self-Assembly.

    Science.gov (United States)

    Hou, Dongwei; Zhang, Guoping; Pant, Rohit Raj; Wei, Zhongxin; Shen, Shuilong

    2016-11-08

    Clay-based nanostructured multilayers, such as clay-polymer multilayers and clay-oxide multilayers, have attracted growing attention owing to their remarkable mechanical properties and promising application in various fields. In this paper, synthesis of a new kind of nanostructured clay-oxide multilayers by layer-by-layer self-assembly was explored. Nano-mechanical characterization of 18 clay-based multilayer samples, prepared under as-deposited (i.e., air-dried) and annealing conditions at 400 °C/600 °C with different precursor cations and multilayer structure, were carried out using nanoindentation testing, atomic force microscopy (AFM), and X-ray diffraction (XRD). The influencing factors, including as-deposited and annealing conditions and clay concentrations on the mechanical properties were analyzed. Results show that all of the multilayers exhibit high bonding strength between interlayers. Higher modulus and hardness of clay-based multilayers were obtained with lower clay concentrations than that with higher clay concentrations. Different relationships between the modulus and hardness and the annealing temperature exist for a specific type of clay-oxide multilayer. This work offers the basic and essential knowledge on design of clay-based nanostructured multilayers by layer-by-layer self-assembly.

  15. Hybrid inorganic-organic materials: Novel poly(propylene oxide)-based ceramers, abrasion-resistant sol-gel coatings for metals, and epoxy-clay nanocomposites, with an additional chapter on: Metallocene-catalyzed linear polyethylene

    Science.gov (United States)

    Jordens, Kurt

    1999-12-01

    The sol-gel process has been employed to generate hybrid inorganic-organic network materials. Unique ceramers were prepared based on an alkoxysilane functionalized soft organic oligomer, poly(propylene oxide (PPO), and tetramethoxysilane (TMOS). Despite the formation of covalent bonds between the inorganic and organic constituents, the resulting network materials were phase separated, composed of a silicate rich phase embedded in a matrix of the organic oligomer chains. The behavior of such materials was similar to elastomers containing a reinforcing filler. The study focused on the influence of initial oligomer molecular weight, functionality, and tetramethoxysilane, water, and acid catalyst content on the final structure, mechanical and thermal properties. The sol-gel approach has also been exploited to generate thin, transparent, abrasion resistant coatings for metal substrates. These systems were based on alkoxysilane functionalized diethylenetriamine (DETA) with TMOS, which generated hybrid networks with very high crosslink densities. These materials were applied with great success as abrasion resistant coatings to aluminum, copper, brass, and stainless steel. In another study, intercalated polymer-clay nanocomposites were prepared based on various epoxy networks montmorillonite clay. This work explored the influence of incorporated clay on the adhesive properties of the epoxies. The lap shear strength decreased with increasing day content This was due to a reduction in the toughness of the epoxy. Also, the delaminated (or exfoliated) nanocomposite structure could not be generated. Instead, all nanocomposite systems possessed an intercalated structure. The final project involved the characterization of a series of metallocene catalyzed linear polyethylenes, produced at Phillips Petroleum. Polyolefins synthesized with such new catalyst systems are becoming widely available. The influence of molecular weight and thermal treatment on the mechanical, rheological

  16. Deformation mechanisms and resealing of damage zones in experimentally deformed cemented and un-cemented clay-rich geomaterials, at low bulk strain

    Science.gov (United States)

    Desbois, Guillaume; Urai, Janos L.; Schuck, Bernhardt; Hoehne, Nadine; Oelker, Anne; Bésuelle, Pierre; Viggiani, Gioacchino; Schmatz, Joyce; Klaver, Jop

    2017-04-01

    A microphysics-based understanding of mechanical and fluid flow properties in clay-rich geomaterials is required for extrapolating better constitutive equations beyond the laboratory's time scales, so that predictions over the long term can be made less uncertain. In this contribution, we present microstructural investigations of rocks specimens sheared in triaxial compression at low bulk strain, by using the combination of broad-ion-beam (BIB) milling and scanning electron microscopy (SEM) to infer deformation mechanisms based on microstructures imaged at sub-micron resolution. Two end-member clay-rich geomaterials from European Underground Laboratories (URL) were analysed: (i) the poorly cemented Boom Clay sediment (BC from URL at Mol/Dessel, Belgium; confining pressure [CP] = 0.375 & 1.5 MPa) and (ii) the Callovo-Oxfordian claystone (COx from the URL at Bure, France; CP = 2 & 10 MPa). Although as a first approximation the inelastic bahvior of cemented and uncemented clay-rich geomaterials can be described by similar pressure-dependent hardening plasticity models, deformed samples in this contribution show very contrasting micro-scale behaviour: microstructures reveal brittle-ductile transitional behaviour in BC, whereas deformation in COx is dominantly cataclastic. In Boom Clay, at meso-scale, shear bands exhibit characteristics that are typical of uncemented small-grained clay-rich materials deformed at high shear strains, consisting of anastomosing shears interpreted as Y- and B-shears, which bound the passively deformed microlithons. At micro- down to nano-scale, the strong shape preferential orientation of clay aggregates in the anastomosing shears is interpreted to be responsible of the shear weakness. More over, the reworking of clay aggregates during deformation contributes to the collapsing of porosity in the shear band. Ductile deformation mechanisms represented by grain-rotation, grain-sliding, bending and granular flow mechanisms are strongly involved

  17. Mineral acquisition from clay by budongo forest chimpanzees

    NARCIS (Netherlands)

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

    2015-01-01

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

  18. Evaluation of Used Fuel Disposition in Clay-Bearing Rock

    Energy Technology Data Exchange (ETDEWEB)

    Jove-Colon, Carlos F. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Weck, Philippe F. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hammond, Glenn Edward [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Kuhlman, Kristopher L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Zheng, Liange [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Rutqvist, Jonny [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Kim, Kunhwi [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Houseworth, James [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Caporuscio, Florie Andre [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Cheshire, Michael [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Palaich, Sarah [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Norskog, Katherine E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Zavarin, Mavrik [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Wolery, Thomas J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Jerden, James L. [Argonne National Lab. (ANL), Argonne, IL (United States); Copple, Jacqueline M. [Argonne National Lab. (ANL), Argonne, IL (United States); Cruse, Terry [Argonne National Lab. (ANL), Argonne, IL (United States); Ebert, William L. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2015-09-04

    Deep geological disposal of nuclear waste in clay/shale/argillaceous rock formations has received much consideration given its desirable attributes such as isolation properties (low permeability), geochemically reduced conditions, slow diffusion, sorbtive mineralogy, and geologically widespread (Jové Colón et al., 2014). There is a wealth of gained scientific expertise on the behavior of clay/shale/ argillaceous rock given its focus in international nuclear waste repository programs that includes underground research laboratories (URLs) in Switzerland, France, Belgium, and Japan. Jové Colón et al. (2014) have described some of these investigative efforts in clay rock ranging from site characterization to research on the engineered barrier system (EBS). Evaluations of disposal options that include nuclear waste disposition in clay/shale/argillaceous rock have determined that this host media can accommodate a wide range of waste types. R&D work within the Used Fuel Disposition Campaign (UFDC) assessing thermal effects and fluid-mineral interactions for the disposition of heat-generating waste have so far demonstrated the feasibility for the EBS and clay host rock to withstand high thermal loads. This report represents the continuation of disposal R&D efforts on the advancement and refinement of coupled Thermal-Hydrological-Mechanical-Chemical (THMC), hydrothermal experiments on clay interactions, used fuel degradation (source term), and thermodynamic modeling and database development. The development and implementation of a clay/shale/argillite reference case described in Jové Colón et al. (2014) for FY15 will be documented in another report (Mariner et al. 2015) – only a brief description will be given here. This clay reference case implementation is the result of integration efforts between the GDSA PA and disposal in argillite work packages. The assessment of sacrificial zones in the EBS is being addressed through experimental work along with 1D reactive

  19. Contact micromechanics in granular media with clay

    Energy Technology Data Exchange (ETDEWEB)

    Ita, Stacey Leigh [Univ. of California, Berkeley, CA (United States)

    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.

  20. Reactivity of Calcined Clays

    OpenAIRE

    Danner, Tobias

    2013-01-01

    With 3-5 billion tons cement-produced every year, the cement industry is today the third largest emitter of CO2 in the world after fossil-fuel based energy plants serving heating/cooling of buildings and combustion engines in the transport sector. In a short time, the easiest way to reduce CO2 emission attributed to cement making is to replace a large portion of portland clinker in cement making blended cements, or to replace a part of portland cement in the concrete mixing operation with a s...